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prepared by
Betsy C. Brantley
Valencia College
CHAPTER
17
The Urinary
System and
Fluid, Electrolyte,
and Acid-Base
Balance
© 2013 Pearson Education, Inc.
Chapter 17 Learning Outcomes
• Section 1: Anatomy of the Urinary System
• 17.1
• Describe the location and structural features of the kidneys.
• 17.2
• Describe the structure of the nephron, cite the functions of each
nephron region, and outline the processes involved in forming
urine.
• 17.3
• Trace the pathway of blood flow through a kidney, and compare
the pattern of blood flow in cortical nephrons and juxtamedullary
nephrons.
© 2013 Pearson Education, Inc.
Chapter 17 Learning Outcomes
• Section 2: Overview of Renal Physiology
• 17.4
• Discuss filtration, reabsorption, and secretion at each region of
the nephron and collecting system, and describe the structures
and functions of the renal corpuscle.
• 17.5
• Describe how antidiuretic hormone (ADH) influences the
volume and concentration of urine.
• 17.6
• Summarize the major steps involved in reabsorbing water and
producing urine.
• 17.7
• CLINICAL MODULE Compare and contrast chronic and acute
renal failure and explain the hemodialysis procedure.
© 2013 Pearson Education, Inc.
Chapter 17 Learning Outcomes
• Section 3: Urine Storage and Elimination
• 17.8
• Describe the structures and functions of the ureters, urinary
bladder, and urethra, and explain the micturition reflex.
• 17.9
• CLINICAL MODULE Describe common urinary disorders
related to output and frequency, and describe a urinalysis, along
with typical and atypical urinalysis findings.
• Section 4: Fluid and Electrolyte Balance
• 17.10
• Explain what fluid and mineral balance means, and discuss its
importance for homeostasis.
• 17.11
• Summarize the relationship between sodium and water in
maintaining fluid and electrolyte balance.
© 2013 Pearson Education, Inc.
Chapter 17 Learning Outcomes
• Section 5: Acid-Base Balance
• 17.12
• Explain the role of buffer systems in maintaining acid-base
balance and pH.
• 17.13
• Explain the role of buffer systems in regulating the pH of the
intracellular fluid and the extracellular fluid.
• 17.14
• Describe the compensatory mechanisms involved in
maintaining acid-base balance.
© 2013 Pearson Education, Inc.
Urinary System (Section 1)
• Eliminates excess water, salts, physiological
wastes
• Two kidneys
• Receive 25 percent cardiac output
• Produce urine
• Components of urinary tract include:
• Ureters, which receive urine from kidneys
• Urinary bladder
• Contraction of muscle in walls drives urination
• Urethra
© 2013 Pearson Education, Inc.
Anterior view of the urinary system
Kidneys
Adrenal gland
Ureters
Aorta
Inferior
vena cava
Urinary bladder
Urethra
© 2013 Pearson Education, Inc.
Figure 17 Section 1
Functions of the Urinary System (Section 1)
• Adjust blood volume and blood pressure
• Regulate plasma concentrations of sodium,
potassium, chloride and other ions
• Stabilize blood pH
• Conserve valuable nutrients
• Remove drugs, toxins, and metabolic wastes from
bloodstream
© 2013 Pearson Education, Inc.
Kidney Structure (17.1)
• Located in retroperitoneal position
• Between muscles of posterior body wall and parietal
peritoneum
• Anchored to surrounding structures by renal
fascia
• Dimensions: 10 cm long, 5.5 cm wide, 3 cm thick
• Weighs about 150 g
• Hilum is medial indentation
• Entry/exit point for renal artery, renal nerves, renal vein,
ureter
© 2013 Pearson Education, Inc.
Gross anatomy of the urinary system
Renal fascia
Esophagus
(cut) Left
Diaphragm
adrenal
gland
Vena
cava
Kidney
Left
kidney
Right
kidney
Hilum
Aorta
Ureters
Cut edge of posterior
peritoneum
Rectum
Urinary
bladder
© 2013 Pearson Education, Inc.
Figure 17.1 1 1
Internal Kidney Structure (17.1)
• Fibrous capsule
• Covers outer surface of kidney
• Lines renal sinus
• Renal cortex is superficial region of kidney
• Renal medulla is inner, darker region of kidney
• Renal pyramid conical structure in medulla
• Tip of pyramid called renal papilla
• Renal column separates adjacent pyramids
• Kidney lobe (6–18 per kidney) contains renal pyramid,
overlying renal cortex, and adjacent renal columns
© 2013 Pearson Education, Inc.
Structure of the kidney
Major Structural Landmarks
of the Kidney
Renal
sinus
Fibrous capsule
Fibrous capsule
within renal sinus
Renal cortex
Hilum
Renal
pelvis
Ureter
Renal
papilla
Renal medulla
Renal pyramid
Renal column
Kidney lobe
© 2013 Pearson Education, Inc.
Figure 17.1
2
Pathway of Urine (17.1)
• Urine produced in kidney lobes
• Minor calyx collects urine from each kidney lobe
• Major calyx forms from fusion of 4–5 minor
calyces
• Renal pelvis
• Funnel-shaped structure that collects urine from major
calyces
• Continuous with ureter
© 2013 Pearson Education, Inc.
Frontal section of a human kidney
Minor calyx
Major calyx
Hilum
Renal pelvis
Ureter
© 2013 Pearson Education, Inc.
Figure 17.1
1
Module 17.1 Review
a. Describe the location of the kidneys.
b. Describe the structural landmarks of the kidney.
c. Which structure is a conical mass within the renal
medulla that ends at the renal papilla?
© 2013 Pearson Education, Inc.
Nephron Structure (17.2)
•
Nephron is microscopic structure
•
Performs essential functions of kidney
•
Consists of:
1. Renal corpuscle
•
Water and dissolved solutes forced out of glomerular
capillaries into capsular space in process called
filtration
•
Filtrate moves into tubule
2. Renal tubule
•
© 2013 Pearson Education, Inc.
Modifies and carries filtrate
Nephron Segments (17.2)
1. Renal corpuscle
•
Consists of glomerular capsule and capillary network
called glomerulus
2. Proximal convoluted tubule (PCT)
•
Reabsorbs nutrients from tubular fluid
3. Nephron loop
•
Establishes osmotic gradient in renal medulla
4. Distal convoluted tubule (DCT)
•
Adjusts tubular fluid composition by secretion and
absorption
© 2013 Pearson Education, Inc.
Functional anatomy of a nephron
Nephron
2
Proximal Convoluted Tubule
4
Distal Convoluted Tubule
Renal
tubule
1
Renal Corpuscle
Efferent
arteriole
Afferent
arteriole
Glomerular
capsule
Capsular space
Glomerulus
3
Descending
limb of
nephron loop
begins
Nephron Loop
Ascending
limb of
nephron loop
ends
Ascending
limb
KEY
Filtrate
Water reabsorption
Variable water reabsorption
Solute reabsorption or secretion
Variable solute reabsorption
or secretion
© 2013 Pearson Education, Inc.
Descending
limb
Figure 17.2
1
Collecting System (17.2)
•
Series of tubes carrying tubular fluid away from
nephron
5. Collecting duct
•
Carries tubular fluid through renal medulla
6. Papillary duct
•
Collects tubular fluid from multiple collecting ducts
•
Delivers tubular fluid to minor calyx
© 2013 Pearson Education, Inc.
Collecting system
Collecting System
5
6
© 2013 Pearson Education, Inc.
KEY
Filtrate
Water reabsorption
Variable water reabsorption
Solute reabsorption or secretion
Variable solute reabsorption
or secretion
Collecting Duct
Papillary Duct
Figure 17.2
2
Functional anatomy of a nephron and the collecting system
Nephron
Collecting System
2
Proximal Convoluted Tubule
4
Distal Convoluted Tubule
Renal
tubule
1
Renal Corpuscle
Efferent
arteriole
Afferent
arteriole
Glomerular
capsule
Capsular
space
Glomerulus
5
Descending
limb of
nephron loop
begins
3
Nephron Loop
Ascending
limb of
nephron loop
ends
Ascending
limb
6
KEY
Filtrate
Water reabsorption
Variable water reabsorption
Solute reabsorption or secretion
Variable solute reabsorption
or secretion
© 2013 Pearson Education, Inc.
Collecting Duct
Papillary Duct
Descending
limb
Figure 17.2
1 – 2
Types of Nephrons (17.2)
• 85 percent of all nephrons are cortical nephrons
• Located in superficial cortex
• 15 percent of nephrons are juxtamedullary
nephrons
• Long nephron loops extending deep into renal medulla
• Essential for conserving water and concentrating urine
© 2013 Pearson Education, Inc.
Locations and structures of cortical and juxtamedullary nephrons
RENAL CORTEX
Cortical nephron
Juxtamedullary
nephron
Nephron loop
of cortical nephron
RENAL
MEDULLA
Nephron loop
of juxtamedullary
nephron
© 2013 Pearson Education, Inc.
Figure 17.2
3
Module 17.2 Review
a. List the primary structures of the nephron and
collecting system.
b. Identify the components of the renal corpuscle.
c. What is the difference between fluid formed in the
glomerulus and blood plasma?
© 2013 Pearson Education, Inc.
Circulatory Pattern in the Kidneys (17.3)
• Renal artery delivers blood to kidney and
branches into:
• Segmental arteries in renal sinus, which branch into:
• Interlobar arteries running within renal columns and
branching into:
• Arcuate arteries that arch along boundary between
renal cortex and renal medulla and branch into:
• Cortical radiate arteries that branch into:
• Afferent arterioles that supply each nephron,
specifically a capillary knot known as a
glomerulus
© 2013 Pearson Education, Inc.
Venous Blood Flow in Kidneys (17.3)
• Blood from glomerulus drains into capillaries
around nephron and then into:
• Cortical radiate veins, then to:
• Arcuate veins, then to:
• Interlobar veins, which drain directly into the
renal vein
© 2013 Pearson Education, Inc.
Blood supply to the kidneys
Arcuate arteries
Cortical
radiate
arteries
Afferent
arterioles
Interlobar arteries
Segmental arteries
Renal artery
Glomerulus
Cortical radiate veins
Arcuate veins
Interlobar veins
Renal vein
© 2013 Pearson Education, Inc.
Figure 17.3 11
Capillaries of the Nephron (17.3)
•
Cortical nephron has relatively short nephron
loop
•
Blood flow
1. Afferent arteriole to glomerulus
•
Filtration occurs in glomerulus and blood flows to:
2. Efferent arteriole to:
3. Peritubular capillaries
•
Surround renal tubule
•
Drain into small venules that drain into cortical radiate veins
© 2013 Pearson Education, Inc.
Circulation to a cortical nephron
Glomerulus in
renal corpuscle
2
3
Peritubular capillaries
Efferent arteriole
Start 1
Afferent arteriole
To the cortical
radiate vein
© 2013 Pearson Education, Inc.
Figure 17.3
2
Vasa Recta (17.3)
• Juxtamedullary nephrons have long nephron loops
• Blood flows from peritubular capillaries into vasa
recta
• Long, straight capillaries parallel to nephron loop
• Important in urine concentration
• Blood from vasa recta drains into cortical radiate veins
© 2013 Pearson Education, Inc.
Circulation to a juxtamedullary nephron
Peritubular
capillaries
Efferent
arteriole
Afferent
arteriole
To cortical
radiate vein
Capillaries of the vasa recta
© 2013 Pearson Education, Inc.
Figure 17.3
3
Nephron Innervation (17.3)
• Each kidney has about 1.25 million nephrons
• Both cortical and juxtamedullary nephrons
innervated by renal nerves
• Most renal nerve fibers are sympathetic postganglionic
from celiac plexus and inferior splanchnic nerves
• Adjust blood flow and blood pressure at glomeruli
• Stimulate release of renin
© 2013 Pearson Education, Inc.
Module 17.3 Review
a. Trace the pathway of blood from the renal artery
to the renal vein.
b. Describe how blood enters and leaves a
glomerulus.
c. Describe the vasa recta.
© 2013 Pearson Education, Inc.
Renal Physiology (Section 2)
• Urinary system maintains homeostasis by regulating volume and
composition of blood
• Concentrates urine to 1200–1400 mOsm/L
• Excretes solutes, especially metabolic wastes such as:
• Urea
• By-product of amino acid breakdown
• Creatinine
• Generated by skeletal muscle contraction breaking down
creatine phosphate
• Uric acid
• Formed during recycling nitrogenous bases of RNA
© 2013 Pearson Education, Inc.
© 2013 Pearson Education, Inc.
Figure 17 Section 2
1
Three Processes in Urine Formation
(Section 2)
1. Filtration
•
Blood pressure forces water and solutes across membranes
of glomerular capillaries into capsular space
2. Reabsorption
•
Removal of water and solutes from tubular fluid and
movement into peritubular fluid
3. Secretion
•
Transport of solutes from peritubular fluid across tubular
epithelium into tubular fluid
© 2013 Pearson Education, Inc.
Physiological processes involved in kidney function
Filtration
membrane
Solute
Blood
pressure
Filtrate
Capsular
space
Glomerular
capillary
Filtration
Transport
proteins
Solute
Peritubular
fluid
Tubular
epithelium
Tubular
fluid
Reabsorption
Transport
proteins
Solute
Peritubular
fluid
Tubular
epithelium
Tubular
fluid
Secretion
© 2013 Pearson Education, Inc.
Figure 17 Section 2
2
Balancing Fluid Movements (17.4)
•
Balance between reabsorption and secretion
varies in nephron regions, regulating final volume
and solute concentration of urine
•
Nephron regions include:
1. Renal corpuscle
2. Proximal convoluted tubule (PCT)
3. Nephron loop
4. Distal convoluted tubule (DCT)
5. Collecting system
© 2013 Pearson Education, Inc.
Urine Formation (17.4)
1. Renal corpuscle
•
Filtration produces 180 L/day of filtrate
•
Composition similar to blood plasma without plasma
proteins
2. Proximal convoluted tubule (PCT)
•
Reabsorption primary process here, retrieving
•
60–70 percent water (108–116 L/day)
•
99–100 percent organic substrates
•
60–70 percent sodium and chloride ions
© 2013 Pearson Education, Inc.
Urine Formation (17.4)
3. Nephron loop
•
Reabsorbs 25 percent water (45 L/day)
•
Reabsorbs 20–25 percent sodium and chloride ions
•
Creates concentration gradient in renal medulla
4. Distal convoluted tubule (DCT)
•
•
Reabsorbs variable amounts of water
•
Usually 5 percent (9 L/day)
•
Influenced by ADH
Reabsorbs variable amounts of sodium ions
•
© 2013 Pearson Education, Inc.
Influenced by aldosterone
Urine Formation (17.4)
5. Collecting system
•
•
Reabsorbs variable amounts of water
•
Usually 9.3 percent (16.8 L/day)
•
Influenced by ADH
Reabsorbs variable amounts of sodium ions
•
© 2013 Pearson Education, Inc.
Influenced by aldosterone
An overview of urine formation
2
4
Proximal convoluted tubule (PCT)
Reabsorption of water, ions, and
all organic nutrients
Distal convoluted tubule (DCT)
Reabsorption of variable
amounts of water and sodium
ions (under hormonal control)
Glomerulus
5
Collecting system
Variable reabsorption of
water and sodium (under
hormonal control)
1
Renal corpuscle
Production of filtrate
KEY
Filtration
3
Water
reabsorption
Nephron loop
Reabsorption of
water (descending
limb) and sodium
and chloride ions
(ascending limb)
Variable water
reabsorption
Solute
reabsorption or
secretion
Urine storage and elimination
© 2013 Pearson Education, Inc.
Variable solute
reabsorption or
secretion
Figure 17.4
1
Renal Corpuscle (17.4)
• Afferent arteriole delivers blood to corpuscle
• Glomerulus (capillary knot) surrounded by:
• Glomerular capsule made of inner visceral layer lining
glomerulus and outer parietal layer
• Capsular space between inner and outer layers of capsule
• Efferent arteriole carries blood away from corpuscle
• Smaller diameter than afferent arteriole elevates blood
pressure in glomerulus, aiding filtration
• Juxtaglomerular complex
• Releases renin when glomerular blood pressure falls
© 2013 Pearson Education, Inc.
Glomerular filtration
Glomerular capsule
Capsular space
Initial segment
of renal tubule
Efferent arteriole
DCT
Juxtaglomerular complex
Outer layer
Inner layer
Afferent arteriole
© 2013 Pearson Education, Inc.
Figure 17.4
2
Inner Glomerular Capsule (17.4)
• Layer of cells called podocytes
• Have complex processes or "feet" that wrap around
glomerular capillaries
• Narrow gaps between adjacent processes called
filtration slits
• Materials passing out of capillaries have to pass
through slits (keeps larger solutes from escaping
bloodstream)
© 2013 Pearson Education, Inc.
Podoctyes in glomerular capsule
Filtration slits
Podocyte
A podocyte
© 2013 Pearson Education, Inc.
SEM x 2400
Figure 17.4
3
Module 17.4 Review
a. Identify the three distinct processes of urine
formation in the kidney.
b. Where does filtration exclusively occur in the
kidney?
c. Which hormone is responsible for regulating
sodium ion reabsorption in the DCT and
collecting system?
© 2013 Pearson Education, Inc.
Water Reabsorption (17.5)
• Amount of water reabsorption affects urine volume
and osmotic concentration
• Obligatory water reabsorption
• In locations where cannot prevent water movements
• PCT and descending limb of nephron loop
• Recovers usually 85 percent filtrate volume
• Facultative water reabsorption
• Allows precise control of water reabsorption
• Occurs in DCT and collecting system
© 2013 Pearson Education, Inc.
Obligatory and facultative water reabsorption in the nephron and collecting duct
Obligatory
water
reabsorption
Glomerulus
Glomerular
capsule
Proximal
convoluted
tubule
Facultative water
reabsorption
Distal convoluted
tubule
Collecting
duct
Nephron
loop
KEY
= Water
reabsorption
= Variable water
reabsorption
© 2013 Pearson Education, Inc.
Urine storage
and elimination
Figure 17.5
1
Urine Volume without ADH (17.5)
• Without ADH
• No water reabsorbed in DCT and collecting duct
• No facultative water reabsorption
• Very low urine osmotic concentration
• Very high urine volume
© 2013 Pearson Education, Inc.
Tubule permeabilities and osmotic concentration in urine without ADH
Renal cortex
PCT
DCT
KEY
= Water
reabsorption
= Variable water
reabsorption
= Na+/Cl–
transport
= Antidiuretic
hormone
Increasing osmolarity
Glomerulus
Renal medulla
Solutes
Collecting
duct
Large volume
of dilute urine
© 2013 Pearson Education, Inc.
Figure 17.5
1
Urine Volume with ADH (17.5)
• ADH allows water channels (aquaporins) to form
• Aquaporins appear in apical plasma membranes of DCT
and collecting duct, making these tubules more
permeable to water
• With ADH and aquaporins
• Increased water reabsorption
• Urine osmotic concentration increases
• Urine output decreases
© 2013 Pearson Education, Inc.
Tubule permeabilities and osmotic concentration in urine with ADH
KEY
= Water
reabsorption
= Variable water
reabsorption
= Na+/Cl–
transport
= Antidiuretic
hormone
Increasing osmolarity
Renal cortex
Renal medulla
Small volume of
concentrated urine
© 2013 Pearson Education, Inc.
Figure 17.5
2
Urine Volume (17.5)
• Normal volume about 1200 mL per day with
osmotic concentration 1000 mOsm/L
• Varies individual to individual and day to day
• Polyuria
• Production of excessive amounts urine
• Causes include hormonal or metabolic problems
• Low urine volume indicates serious kidney
problems
• Oliguria (urine volume 50–500 mL/day)
• Anuria (urine volume 0–50 mL/day)
© 2013 Pearson Education, Inc.
© 2013 Pearson Education, Inc.
Figure 17.5
3
Module 17.5 Review
a. Can the permeability of the PCT to water ever
change? Why or why not?
b. How would an increase in ADH levels affect the
DCT?
c. When ADH levels in the DCT decrease, what
happens to the urine osmotic concentration?
© 2013 Pearson Education, Inc.
Renal Function Overview (17.6)
1. Filtrate produced in renal corpuscle
2. Water, ions, organic nutrients removed from tubular fluid
in PCT
•
Reducing volume but maintaining osmotic concentration
3. Obligatory water reabsorption occurs in PCT and
descending limb of nephron loop
•
Concentrating tubular fluid
4. Ascending limb of nephron loop permeable to Na+ and Cl–
(which move out of tubule) but not to water
•
Lowers osmotic concentration of tubular fluid
© 2013 Pearson Education, Inc.
Renal Function Overview (17.6)
5. Composition of tubular fluid adjusted in DCT and
collecting system
6. Final adjustments in volume and concentration in
DCT and collecting system due to ADH presence
or absence
7. Vasa recta absorbs solutes and water
reabsorbed by nephron loop and collecting ducts
•
Transports solutes and water into venous system
•
Maintains concentration gradient of renal medulla
© 2013 Pearson Education, Inc.
Slide 1
Summary of renal function
Renal cortex
1
300
KEY
= Water
reabsorption
= Variable water
reabsorption
= Na+/Cl–
transport
A
= Aldosteroneregulated pump
© 2013 Pearson Education, Inc.
Figure 17.6
Slide 2
Summary of renal function
Renal cortex
PCT
1
300
1
Nutrients
300
Electrolytes
2
2
KEY
= Water
reabsorption
= Variable water
reabsorption
= Na+/Cl–
transport
A
= Aldosteroneregulated pump
© 2013 Pearson Education, Inc.
Figure 17.6
Slide 3
Summary of renal function
Renal cortex
PCT
1
300
1
Nutrients
300
Electrolytes
2
2
600
3
3
Vasa
recta
900
Nephron
loop
Renal medulla
KEY
1200
= Water
reabsorption
= Variable water
reabsorption
= Na+/Cl–
transport
A
= Aldosteroneregulated pump
© 2013 Pearson Education, Inc.
Figure 17.6
Slide 4
Summary of renal function
Renal cortex
4
DCT
PCT
1
4
300
1
Nutrients
300
Electrolytes
2
2
600
3
Vasa
recta
900
Increasing osmolarity
3
Nephron
loop
Renal medulla
Nephron
loop
KEY
1200
= Water
reabsorption
= Variable water
reabsorption
Vasa
recta
1200
= Na+/Cl–
transport
A
= Aldosteroneregulated pump
© 2013 Pearson Education, Inc.
Figure 17.6
Slide 5
Summary of renal function
Renal cortex
4
Tubular fluid
from cortical
nephrons
DCT
PCT
1
4
300
1
A
Nutrients
100–300
300
5
Electrolytes
5
2
2
600
3
Vasa
recta
900
Increasing osmolarity
3
Nephron
loop
Renal medulla
Nephron
loop
KEY
1200
= Water
reabsorption
= Variable water
reabsorption
Vasa
recta
1200
= Na+/Cl–
transport
A
= Aldosteroneregulated pump
© 2013 Pearson Education, Inc.
Figure 17.6
Slide 6
Summary of renal function
Renal cortex
4
Tubular fluid
from cortical
nephrons
DCT
PCT
1
4
300
1
A
Nutrients
100–300
300
5
Electrolytes
5
2
2
Collecting
duct
A
600
Vasa
recta
900
Increasing osmolarity
3
6
600
3
ADHregulated
permeability
900
Nephron
loop
Renal medulla
Nephron
loop
KEY
1200
= Water
reabsorption
= Variable water
reabsorption
Vasa
recta
1200
= Na+/Cl–
transport
A
= Aldosteroneregulated pump
© 2013 Pearson Education, Inc.
Figure 17.6
Slide 7
Summary of renal function
Renal cortex
4
Tubular fluid
from cortical
nephrons
DCT
PCT
1
4
300
1
A
Nutrients
100–300
300
5
Electrolytes
5
2
2
Collecting
duct
A
600
Vasa
recta
900
Increasing osmolarity
3
6
600
3
ADHregulated
permeability
900
Nephron
loop
Renal medulla
7
Nephron
loop
KEY
1200
= Water
reabsorption
= Variable water
reabsorption
= Na+/Cl–
transport
A
= Aldosteroneregulated pump
© 2013 Pearson Education, Inc.
Vasa
recta
1200
1200
Urine enters
renal pelvis
Figure 17.6
Module 17.6 Review
a. The filtrate produced at the renal corpuscle has
the same osmotic pressure as _____.
b. In the PCT, ions and organic substrates are
actively reabsorbed, thus causing what to occur?
c. How is the concentration gradient of the renal
medulla maintained?
© 2013 Pearson Education, Inc.
Renal Failure (17.7)
• Kidneys unable to perform excretory functions to
maintain homeostasis
• Impairs all systems in body resulting in:
• Reduced urine production
• Disturbed fluid balance, pH, muscular contraction,
metabolism, and digestive function
• Hypertension
• Anemia from decline in erythropoietin production
• Central nervous system problems (sleeplessness, seizures,
delirium, and coma)
© 2013 Pearson Education, Inc.
Acute Renal Failure (17.7)
• Kidney function deteriorates rapidly in just a few days
• May be impaired for weeks
• Sudden slowing or stopping of filtration caused by:
• Exposure to toxic drugs, renal ischemia, urinary
obstruction, or trauma
• Allergic response to antibiotics or anesthetics in
sensitized individuals
• Recovery of partial or complete function possible if
survive initial incident
© 2013 Pearson Education, Inc.
Chronic Renal Failure (17.7)
• Kidney function deteriorates gradually
• Associated problems accumulate over time
• Progression can be slowed, but condition not reversible
• Management involves restricting water, salt, and protein
intake
• Reduces strain on urinary system by minimizing:
1. Volume of urine produced
2. Amount of nitrogenous waste generated
• Acidosis, common problem with renal failure, can be
countered by ingesting bicarbonate ions
© 2013 Pearson Education, Inc.
Dialysis (17.7)
• Process of passive diffusion across a selectively
permeable membrane
• Hemodialysis uses artificial membrane as
alternative to kidney's normal membrane around
glomerulus
• Regulates composition of blood using dialysis machine
• Membrane pores allow diffusion of ions, nutrients,
organic wastes but not plasma proteins
• Dialysis fluid containing specific concentrations of
solutes on other side of membrane
© 2013 Pearson Education, Inc.
Hemodialysis uses an artificial membrane
Artificial dialysis membrane
Blood
Plasma
proteins
Dialysis fluid
Small ion
Organic waste
© 2013 Pearson Education, Inc.
Figure 17.7
2
© 2013 Pearson Education, Inc.
Figure 17.7
2
Renal Failure Treatment (17.7)
• With acute renal failure, kidneys may regain partial or
complete function (survival rate 50 percent with treatment)
• With chronic renal failure, treatment can slow
progression but not stop
• Hemodialysis relieves signs and symptoms of renal failure,
but is not a cure
• Renal transplant only real cure for severe renal failure
• One-year success rate 85–95 percent
• Recipient on immunosuppressive drugs for life
© 2013 Pearson Education, Inc.
Hemodialysis process
As diffusion takes place across the dialysis membrane, the composition of the blood
changes. Potassium ions, phosphate ions, sulfate ions, urea, creatinine, and uric acid diffuse
across the membrane into the dialysis fluid. Bicarbonate ions and glucose diffuse from
the dialysis fluid into the bloodstream. In effect, diffusion across the dialysis membrane
takes the place of normal glomerular filtration, and the characteristics of the dialysis fluid
ensure that important metabolites (substances necessary for a metabolic process) remain in
the blood rather than diffusing across the membrane.
Thermometer
Blood
pump
Dialysis
fluid
Dialysis
chamber
Holding
tank
To drain
Flow
meter
Blood
flowing
in a tube
of dialysis
membrane
In practice, silicone rubber tubes called
shunts are inserted into a medium-sized
artery and vein. (The typical location is the
forearm, although the lower leg is sometimes
used.) The two shunts are then connected,
forming a short circuit that does not impede
the flow of blood. The shunts can then be
used like taps in a wine barrel, to draw a
blood sample or to connect the individual to
a dialysis machine. For long-term dialysis, a
surgically created arteriovenous anastomosis
provides access.
Air detector
and clamp
Artery
© 2013 Pearson Education, Inc.
Vein
Figure 17.7
3
Module 17.7 Review
a. Define hemodialysis.
b. Briefly explain the difference between chronic
renal failure and acute renal failure.
c. Explain why patients on dialysis often receive
Epogen or Procrit, a synthetic form of
erythropoietin.
© 2013 Pearson Education, Inc.
Urine Storage and Elimination (Section 3)
• Urinary tract transports, stores, and eliminates
urine
• Can visualize tract using pyelogram
• Ureters
• Paired muscular tubes from kidney to urinary bladder (about
30 cm)
• Retroperitoneal and attached to posterior abdominal wall
• Urinary bladder
• Hollow, muscular organ holding up to a liter of urine
• Urethra
© 2013 Pearson Education, Inc.
Pyelogram of urinary structures
Renal pelvis
Kidney
Ureters
Urinary bladder
© 2013 Pearson Education, Inc.
Figure 17 Section 3
1
Urethra (Section 3)
• Extends from neck of urinary bladder to exterior
of body
• Different lengths and functions in males versus
females
• Male urethra is longer and transports semen as well
as urine
© 2013 Pearson Education, Inc.
Organs for conduction and storage of urine
Ureter
Urinary bladder
Urethra
Male
© 2013 Pearson Education, Inc.
Female
Figure 17 Section 3
2
Urinary Bladder and Urination (17.8)
• Process of urination is micturition
• Wall of urinary bladder
• Mucosa, submucosa, muscularis layers
• Muscularis (also called detrusor muscle) has inner and
outer layers of longitudinal smooth muscle and additional
circular layer between
• Contraction of muscle compresses bladder, expelling
urine into urethra
© 2013 Pearson Education, Inc.
Structures of the Urinary Bladder (17.8)
• Rugae are folds in bladder lining that disappear
with expansion upon filling
• Ureteral openings
• Slitlike shape helps prevent backflow of urine into ureters
with bladder contraction
• Ureters penetrate posterior bladder wall at oblique angle
• Trigone is triangular area bounded by ureteral
openings and entrance to urethra
• Neck of urinary the bladder surrounds urethral
opening
© 2013 Pearson Education, Inc.
Urinary bladder in male
Wall of urinary bladder with detrusor muscle
Ureters
Ureteral openings
Trigone
Rugae
Urethra
Prostate
gland
(males
only)
Neck of urinary
bladder containing
internal urethral
sphincter
External urethral sphincter
© 2013 Pearson Education, Inc.
Figure 17.8
1
Urethral Sphincters (17.8)
• Internal urethral sphincter
• Found in neck of urinary bladder
• Involuntary smooth muscle
• External urethral sphincter
• Located where urethra passes through urogenital
diaphragm
• Under voluntary control
• Must be voluntarily relaxed to permit urination
© 2013 Pearson Education, Inc.
Micturition Reflex (17.8)
1. Increasing urine volume stimulates stretch
receptors in urinary bladder wall
2. Afferent fibers carry information to sacral spinal
cord
3. Parasympathetic motor fibers carry commands
back to urinary bladder
4. Postganglionic neurons in bladder stimulate
detrusor muscle to contract
5. Voluntary relaxation of external urethral sphincter
causes relaxation of internal urethral sphincter
leading to urination
© 2013 Pearson Education, Inc.
Micturation reflex
Voluntary command from cerebral cortex
2
3
Parasympathetic preganglionic
motor fibers in pelvic nerves carry
motor commands back to the
urinary bladder.
Afferent fibers in the
pelvic nerves carry
the information to
the sacral spinal cord.
4
Start 1
The process begins
when increasing urine
volume distorts stretch
receptors in the wall of
the urinary bladder.
Postganglionic neurons within the
bladder stimulate the detrusor
muscle to contract. This raises
pressure in the urinary bladder.
Urinary
bladder
5
Voluntary relaxation of the external urethral
sphincter causes the internal urethral sphincter
to relax. Because the local pathway already has
elevated pressures within the urinary bladder,
relaxation of these sphincters leads to urination.
Urination occurs
© 2013 Pearson Education, Inc.
Figure 17.8
2
Urination Control (17.8)
• Urge to urinate appears when about 200 mL urine
in bladder
• After micturition, less than 10 mL left in bladder
• Voluntary control of external urethral sphincter
• Requires corticospinal connections
• Does not develop until about age 2
© 2013 Pearson Education, Inc.
Module 17.8 Review
a. Urine is transported by the ______, stored within
the ______, and eliminated through the _____.
b. What has to happen to the external urethral
sphincter to allow urination?
c. Describe the micturition reflex.
© 2013 Pearson Education, Inc.
Urinary Disorders (17.9)
• Detected by changes in:
• Volume and appearance of urine
• Frequency of urination
• Pain in various locations may indicate:
• Urinary bladder disorders
• Pyelonephritis (kidney infection)
• Renal calculi (kidney stones)
• Dysuria (painful or difficult urination) may indicate:
• Cystitis or urethritis
• Urinary obstruction
© 2013 Pearson Education, Inc.
Location of pain associated with urinary disorders
Pain in the superior pubic
region may be associated
with urinary bladder
disorders.
© 2013 Pearson Education, Inc.
Pain in the superior lumbar
region or in the flank that
radiates to the right upper
quadrant or left upper
quadrant can be caused by
kidney infections such as
pyelonephritis, or by kidney
stones (renal calculi).
Dysuria (painful or difficult
urination) can occur with
cystitis or urethritis, or with
urinary obstructions. In males,
an enlarged prostate gland can
compress the urethra and lead
to dysuria.
Figure 17.9
1
Important Clinical Signs of Urinary System
Disorders (17.9)
• Edema (swelling)
• Renal disorders often lead to protein loss in urine
(proteinuria)
• Severe proteinuria may cause generalized edema in
peripheral tissues
• Facial swelling common, especially around eyes
• Fever
• Commonly develops when pathogens infect urinary system
• Low-grade fever with urinary bladder infections (cystitis)
• Very high fevers with kidney infections, such as pyelonephritis
© 2013 Pearson Education, Inc.
Abnormal Urine Output and Frequency (17.9)
• Increased urgency or increased frequency
• Indicates irritation of lining of ureters or urinary bladder
• Changes in urinary output
• Indicate problems with kidneys or control of renal function
• Incontinence
• Inability to control voluntary urination (stress, urge, overflow)
• Urinary retention
• Kidney function normal but no urination
• Enlarged prostate common cause of retention in males
© 2013 Pearson Education, Inc.
Abnormal Urine Output and Frequency (17.9)
• Increased urgency or increased frequency
• Indicates irritation of lining of ureters or urinary bladder
• Leads to desire to urinate more often
• Amount of urine produced each day remains normal
• Changes in urinary output
• If occurs with no change in fluid intake, indicates
problems with kidneys or control of renal function
© 2013 Pearson Education, Inc.
Abnormal Urine Output and Frequency (17.9)
• Incontinence
• Inability to control voluntary urination including:
1. Periodic involuntary leakage (stress incontinence)
2. Inability to delay urination (urge incontinence)
3. Continual, slow trickle of urine from bladder that is
always full (overflow incontinence)
• Urinary retention
• Kidney function normal but no urination
• Enlarged prostate common cause of retention in males
© 2013 Pearson Education, Inc.
Urinalysis (17.9)
• Clinical examination of urine sample
• Chemical analysis
• Screening tests using test strips dipped in sample
• Detect changes in pH, glucose, ketones, bilirubin,
urobilinogen, plasma proteins, and hemoglobin
• Pregnancy test
• Detects hormone, human chorionic gonadotropin (hCG)
© 2013 Pearson Education, Inc.
Urinalysis test strip
© 2013 Pearson Education, Inc.
Figure 17.9
4
Sediment Analysis (17.9)
• Urine sample spun in centrifuge
• Can examine resulting sediment under microscope
• Sediment contents may include mineral crystals and
deposits called casts, which indicate potential issues
• If RBCs or WBCs, then glomerular damage or inflammation or
infection
• If bacteria, then urinary tract infection
• Casts have protein coat and form in DCTs and collecting
ducts
© 2013 Pearson Education, Inc.
© 2013 Pearson Education, Inc.
Figure 17.9
5
Module 17.9 Review
a. What is the term for painful or difficult urination?
b. If a kidney stone obstructs a ureter, this would
interfere with the flow of urine between which two
points?
c. What types of casts might you find in urine
sediment?
© 2013 Pearson Education, Inc.
Fluid Compartments (Section 4)
• Inorganic components of body are water and
minerals
• Water is distributed in fluid compartments
• Intracellular fluid (ICF) or cytosol
• Percentage varies between males and females due to
intracellular water content of fat versus muscle cells
• Extracellular fluid (ECF)
• Percentage varies between males and females due to
larger blood volume in males and varying interstitial
volume in different tissues
© 2013 Pearson Education, Inc.
A comparison of body composition of adult males and females
ICF
ECF
Intracellular Interstitial
fluid 33% fluid 21.5%
Plasma
4.5%
Solids 40%
(organic and inorganic materials)
Other
body
fluids
(≤1%)
Adult males
ICF
ECF
Intracellular Interstitial
fluid 27%
fluid 18%
Solids 50%
(organic and inorganic materials)
Adult females
© 2013 Pearson Education, Inc.
Other
body
fluids
(≤1%)
Figure 17 Section 4
1
Solid Components (Section 4)
• Solid components of the body
• Account for 40–50 percent mass of body
• Include organic and inorganic components
• Proteins, lipids, minerals, and carbohydrates
• Minerals
• Inorganic substances that dissociate into body fluids to
form electrolytes
© 2013 Pearson Education, Inc.
Solid components of body composition by weight
SOLID COMPONENTS
(31.5 kg; 69.3 lbs)
15
10
Kg
5
0
Proteins
© 2013 Pearson Education, Inc.
Lipids
Minerals
Carbohydrates Miscellaneous
Figure 17 Section 4
2
Fluid Balance (17.10)
• Balanced when amount of water gained each day equal to
amount of water lost
• Water gained through:
• Digestive tract and metabolic processes
• Water lost through:
• Feces, urination, and evaporation (sweating)
• Water moves through osmosis, flowing down osmotic
gradient
© 2013 Pearson Education, Inc.
Water balance in the body
Dietary Input
Digestive Secretions
Food and drink
2200 mL
Saliva 1500 mL
Water Created
During
Metabolism
300 mL
Water Elimination
1150 mL lost by
evaporation from
lungs and moist
surfaces
Water secreted by
sweat glands
(variable)
1200 mL lost
by urination
5200
mL
9200 mL
Water Reabsorption
Small intestine
reabsorbs 8000 mL
Colon reabsorbs
1250 mL
1400
mL
Gastric secretions
1500 mL
Liver (bile) 1000 mL
Pancreas (pancreatic
juice) 1000 mL
Intestinal secretions
2000 mL
Colonic mucous
secretions 200 mL
Water Elimination
150 mL lost in feces
© 2013 Pearson Education, Inc.
Figure 17.10
1
Fluid Shifts (17.10)
• Composition of ICF and ECF very different, yet at
osmotic equilibrium
• Fluid shifts
• Movement of water between ECF and ICF in response
to osmotic gradient
• Occur rapidly with ECF osmotic concentration change
• Equilibrium reached in minutes to hours
© 2013 Pearson Education, Inc.
Fluid gains and losses
Water absorbed across
digestive epithelium
(2200 mL)
Metabolic
water
ICF
(300 mL)
ECF
Water vapor lost
in respiration and
evaporation from
moist surfaces
(1150 mL)
Water lost in
feces (150 mL)
Water secreted
by sweat glands
(variable)
Plasma membranes of tissue cells Water lost in urine (1200 mL)
© 2013 Pearson Education, Inc.
Figure 17.10
2
Mineral Balance (17.10)
• Balance between ion absorption and ion
excretion
• Absorption
• Occurs across lining of small intestine and colon
• Excretion
• Occurs primarily at kidneys
• Variable rate of loss at sweat glands
• Body maintains reserves of key minerals
• Daily intake has to average amount lost each day
to stay in mineral balance
© 2013 Pearson Education, Inc.
Mineral balance
Ion absorption
Ion absorption occurs across
the epithelial lining of the
small intestine and colon.
Ion reserves (primarily
in the skeleton)
Ion excretion
Sweat gland
secretions
(secondary site
of ion loss)
Ion pool in body fluids
ICF
© 2013 Pearson Education, Inc.
ECF
Kidneys
(primary site of
ion loss)
Figure 17.10
3
© 2013 Pearson Education, Inc.
Figure 17.10
4
Module 17.10 Review
a. Identify routes of fluid loss from the body.
b. Describe a fluid shift.
c. Define fluid balance and mineral balance.
© 2013 Pearson Education, Inc.
Sodium Balance (17.11)
• When sodium gains equal sodium losses
• Mechanism involves changes in ECF volume while
keeping Na+ concentration stable
• Sodium gains exceed losses, then ECF volume increases
• Sodium losses exceed gains, then ECF volume decreases
• Small changes in ECF volume do not cause
adverse physiological effects
© 2013 Pearson Education, Inc.
Homeostatic regulation of normal
sodium ion concentrations in body fluids
Slide 1
Rising plasma
sodium levels
Consumption of large
amounts of salt
HOMEOSTASIS
DISTURBED
Na+ levels
in ECF rise
HOMEOSTASIS
Normal Na+
concentration
in ECF
© 2013 Pearson Education, Inc.
Start
Figure 17.11
1
Homeostatic regulation of normal
sodium ion concentrations in body fluids
Rising plasma
sodium levels
ADH Secretion Increases
Slide 2
The secretion of ADH restricts
water loss and stimulates
thirst, promoting additional
water consumption.
Stimulate
osmoreceptors in
hypothalamus
Consumption of large
amounts of salt
HOMEOSTASIS
DISTURBED
Na+ levels
in ECF rise
HOMEOSTASIS
Normal Na+
concentration
in ECF
© 2013 Pearson Education, Inc.
Start
Figure 17.11
1
Homeostatic regulation of normal
sodium ion concentrations in body fluids
Rising plasma
sodium levels
ADH Secretion Increases
The secretion of ADH restricts
water loss and stimulates
thirst, promoting additional
water consumption.
Recall of Fluids
Slide 3
Because the ECF
osmolarity increases,
water shifts out of the
ICF, increasing ECF
volume and lowering
ECF Na+ concentrations.
Stimulate
osmoreceptors in
hypothalamus
Consumption of large
amounts of salt
HOMEOSTASIS
DISTURBED
Na+ levels
in ECF rise
HOMEOSTASIS
Normal Na+
concentration
in ECF
© 2013 Pearson Education, Inc.
Start
Figure 17.11
1
Homeostatic regulation of normal
sodium ion concentrations in body fluids
Rising plasma
sodium levels
ADH Secretion Increases
The secretion of ADH restricts
water loss and stimulates
thirst, promoting additional
water consumption.
Recall of Fluids
Slide 4
Because the ECF
osmolarity increases,
water shifts out of the
ICF, increasing ECF
volume and lowering
ECF Na+ concentrations.
Stimulate
osmoreceptors in
hypothalamus
Consumption of large
amounts of salt
HOMEOSTASIS
RESTORED
HOMEOSTASIS
DISTURBED
Na+ levels
in ECF fall
Na+ levels
in ECF rise
HOMEOSTASIS
Normal Na+
concentration
in ECF
© 2013 Pearson Education, Inc.
Start
Figure 17.11
1
Homeostatic regulation of normal
sodium ion concentrations in body fluids
Rising plasma
sodium levels
ADH Secretion Increases
The secretion of ADH restricts
water loss and stimulates
thirst, promoting additional
water consumption.
Recall of Fluids
Slide 5
Because the ECF
osmolarity increases,
water shifts out of the
ICF, increasing ECF
volume and lowering
ECF Na+ concentrations.
Stimulate
osmoreceptors in
hypothalamus
Consumption of large
amounts of salt
HOMEOSTASIS
RESTORED
HOMEOSTASIS
DISTURBED
Na+ levels
in ECF fall
Na+ levels
in ECF rise
HOMEOSTASIS
Normal Na+
concentration
in ECF
Start
HOMEOSTASIS
DISTURBED
Na+ levels
in ECF fall
Falling plasma
sodium levels
© 2013 Pearson Education, Inc.
Figure 17.11
1
Homeostatic regulation of normal
sodium ion concentrations in body fluids
Rising plasma
sodium levels
ADH Secretion Increases
Recall of Fluids
The secretion of ADH restricts
water loss and stimulates
thirst, promoting additional
water consumption.
Slide 6
Because the ECF
osmolarity increases,
water shifts out of the
ICF, increasing ECF
volume and lowering
ECF Na+ concentrations.
Stimulate
osmoreceptors in
hypothalamus
Consumption of large
amounts of salt
HOMEOSTASIS
RESTORED
HOMEOSTASIS
DISTURBED
Na+ levels
in ECF fall
Na+ levels
in ECF rise
HOMEOSTASIS
Normal Na+
concentration
in ECF
Start
HOMEOSTASIS
DISTURBED
Na+ levels
in ECF fall
Inhibit
osmoreceptors in
hypothalamus
Falling plasma
sodium levels
© 2013 Pearson Education, Inc.
ADH Secretion
Decreases
As soon as the osmotic
concentration of the ECF
drops by 2 percent or more,
ADH secretion decreases,
so thirst is suppressed and
water losses at the kidneys
increase.
Figure 17.11
1
Homeostatic regulation of normal
sodium ion concentrations in body fluids
Rising plasma
sodium levels
ADH Secretion Increases
Recall of Fluids
The secretion of ADH restricts
water loss and stimulates
thirst, promoting additional
water consumption.
Slide 7
Because the ECF
osmolarity increases,
water shifts out of the
ICF, increasing ECF
volume and lowering
ECF Na+ concentrations.
Stimulate
osmoreceptors in
hypothalamus
Consumption of large
amounts of salt
HOMEOSTASIS
RESTORED
HOMEOSTASIS
DISTURBED
Na+ levels
in ECF fall
Na+ levels
in ECF rise
HOMEOSTASIS
Normal Na+
concentration
in ECF
HOMEOSTASIS
DISTURBED
HOMEOSTASIS
RESTORED
Na+ levels
in ECF fall
Na+ levels
in ECF rise
Inhibit
osmoreceptors in
hypothalamus
Falling plasma
sodium levels
© 2013 Pearson Education, Inc.
Start
ADH Secretion
Decreases
As soon as the osmotic
concentration of the ECF
drops by 2 percent or more,
ADH secretion decreases,
so thirst is suppressed and
water losses at the kidneys
increase.
Water loss reduces
ECF volume,
concentrates ions
Figure 17.11
1
Blood Volume Balance (17.11)
• If ECF volume is disturbed significantly,
homeostatic mechanisms are activated
• ECF volume increases, blood volume increases
• Mechanisms respond to lower blood volume
• ECF volume decreases, blood volume decreases
• Mechanisms respond to increase blood volume
• Only see sustained sodium imbalances in ECF
secondary to severe fluid balance problems
© 2013 Pearson Education, Inc.
Slide 1
Sodium ion concentration and fluid
volume regulation in body fluids
Rising blood
pressure and
volume
HOMEOSTASIS
DISTURBED
Fluid gain or fluid and
Na+ gain raise ECF volume
HOMEOSTASIS
Start
Normal ECF
volume
© 2013 Pearson Education, Inc.
Figure 17.11
2
Slide 2
Sodium ion concentration and fluid
volume regulation in body fluids
Rising blood
pressure and
volume
Cardiac muscle
cells release atrial
natriuretic peptide
Increase blood
volume and
atrial distension
HOMEOSTASIS
DISTURBED
Fluid gain or fluid and
Na+ gain raise ECF volume
HOMEOSTASIS
Start
Normal ECF
volume
© 2013 Pearson Education, Inc.
Figure 17.11
2
Sodium ion concentration and fluid
volume regulation in body fluids
Rising blood
pressure and
volume
Cardiac muscle
cells release atrial
natriuretic peptide
Slide 3
Responses to Atrial Natriuretic Peptide
Increase Na+ loss in urine
Increase water loss in urine
Reduce thirst
Inhibit ADH, aldosterone, epinephrine,
and norepinephrine release
Increase blood
volume and
atrial distension
HOMEOSTASIS
DISTURBED
Fluid gain or fluid and
Na+ gain raise ECF volume
HOMEOSTASIS
Start
Normal ECF
volume
© 2013 Pearson Education, Inc.
Figure 17.11
2
Sodium ion concentration and fluid
volume regulation in body fluids
Rising blood
pressure and
volume
Cardiac muscle
cells release atrial
natriuretic peptide
Responses to Atrial Natriuretic Peptide
Increase Na+ loss in urine
Combined
Effects
Slide 4
Reduce
blood
volume
Increase water loss in urine
Reduce thirst
Inhibit ADH, aldosterone, epinephrine,
and norepinephrine release
Reduce
blood
pressure
Increase blood
volume and
atrial distension
HOMEOSTASIS
RESTORED
HOMEOSTASIS
DISTURBED
Fluid gain or fluid and
Na+ gain raise ECF volume
ECF volume
falls
HOMEOSTASIS
Start
Normal ECF
volume
© 2013 Pearson Education, Inc.
Figure 17.11
2
Sodium ion concentration and fluid
volume regulation in body fluids
Rising blood
pressure and
volume
Cardiac muscle
cells release atrial
natriuretic peptide
Responses to Atrial Natriuretic Peptide
Increase Na+ loss in urine
Combined
Effects
Slide 5
Reduce
blood
volume
Increase water loss in urine
Reduce thirst
Inhibit ADH, aldosterone, epinephrine,
and norepinephrine release
Reduce
blood
pressure
Increase blood
volume and
atrial distension
HOMEOSTASIS
RESTORED
HOMEOSTASIS
DISTURBED
Fluid gain or fluid and
Na+ gain raise ECF volume
HOMEOSTASIS
DISTURBED
ECF volume
falls
HOMEOSTASIS
Start
Normal ECF
volume
Fluid loss or fluid and
Na+ loss lower ECF volume
Falling blood
pressure and
volume
© 2013 Pearson Education, Inc.
Figure 17.11
2
Sodium ion concentration and fluid
volume regulation in body fluids
Rising blood
pressure and
volume
Cardiac muscle
cells release atrial
natriuretic peptide
Responses to Atrial Natriuretic Peptide
Increase Na+ loss in urine
Combined
Effects
Slide 6
Reduce
blood
volume
Increase water loss in urine
Reduce thirst
Inhibit ADH, aldosterone, epinephrine,
and norepinephrine release
Reduce
blood
pressure
Increase blood
volume and
atrial distension
HOMEOSTASIS
RESTORED
HOMEOSTASIS
DISTURBED
Fluid gain or fluid and
Na+ gain raise ECF volume
ECF volume
falls
HOMEOSTASIS
Start
Normal ECF
volume
HOMEOSTASIS
DISTURBED
Fluid loss or fluid and
Na+ loss lower ECF volume
Decrease blood
volume and
blood pressure
Endocrine Responses
Increase renin secretion and
angiotensin II activation
Falling blood
pressure and
volume
© 2013 Pearson Education, Inc.
Increase aldosterone release
Increase ADH release
Figure 17.11
2
Sodium ion concentration and fluid
volume regulation in body fluids
Rising blood
pressure and
volume
Cardiac muscle
cells release atrial
natriuretic peptide
Responses to Atrial Natriuretic Peptide
Combined
Effects
Increase Na+ loss in urine
Slide 7
Reduce
blood
volume
Increase water loss in urine
Reduce thirst
Reduce
blood
pressure
Inhibit ADH, aldosterone, epinephrine,
and norepinephrine release
Increase blood
volume and
atrial distension
HOMEOSTASIS
RESTORED
HOMEOSTASIS
DISTURBED
Fluid gain or fluid and
Na+ gain raise ECF volume
ECF volume
falls
HOMEOSTASIS
Start
Normal ECF
volume
HOMEOSTASIS
DISTURBED
Fluid loss or fluid and
Na+ loss lower ECF volume
Decrease blood
volume and
blood pressure
Falling blood
pressure and
volume
© 2013 Pearson Education, Inc.
Endocrine Responses
Combined Effects
Increase renin secretion and
angiotensin II activation
Increase urinary Na+ retention
Increase aldosterone release
Increase thirst
Increase ADH release
Increase water intake
Decrease urinary water loss
Figure 17.11
2
Sodium ion concentration and fluid
volume regulation in body fluids
Rising blood
pressure and
volume
Cardiac muscle
cells release atrial
natriuretic peptide
Responses to Atrial Natriuretic Peptide
Combined
Effects
Increase Na+ loss in urine
Slide 8
Reduce
blood
volume
Increase water loss in urine
Reduce thirst
Reduce
blood
pressure
Inhibit ADH, aldosterone, epinephrine,
and norepinephrine release
Increase blood
volume and
atrial distension
HOMEOSTASIS
RESTORED
HOMEOSTASIS
DISTURBED
Fluid gain or fluid and
Na+ gain raise ECF volume
ECF volume
falls
HOMEOSTASIS
Normal ECF
volume
HOMEOSTASIS
DISTURBED
Fluid loss or fluid and
Na+ loss lower ECF volume
Decrease blood
volume and
blood pressure
Falling blood
pressure and
volume
© 2013 Pearson Education, Inc.
Start
HOMEOSTASIS
RESTORED
ECF volume
rises
Endocrine Responses
Combined Effects
Increase renin secretion and
angiotensin II activation
Increase urinary Na+ retention
Increase aldosterone release
Increase thirst
Increase ADH release
Increase water intake
Decrease urinary water loss
Figure 17.11
2
Module 17.11 Review
a. What effect does inhibition of osmoreceptors
have on ADH secretion and thirst?
b. What effect does aldosterone have on sodium ion
concentration in the ECF?
c. Briefly summarize the relationship between
sodium ion concentration and the ECF.
© 2013 Pearson Education, Inc.
Acid-Base Balance (Section 5)
• pH measure of hydrogen ion concentration
• Normal blood plasma pH 7.35–7.45
• Body is in acid-base balance when:
• pH of body fluids are within normal limits
• Production of hydrogen ions is precisely offset by loss of
hydrogen ions
• Normal metabolic processes produce acids
• Body excretes acidic and basic substances
© 2013 Pearson Education, Inc.
Major factors invovlved in maintaining acid-base balance
The respiratory system plays a key role
in acid-base balance by eliminating
carbon dioxide. When the respiratory
rate increases, more carbon dioxide is
eliminated. When the respiratory rate
decreases, carbon dioxide accumulates
in the blood.
Active tissues continuously generate carbon
dioxide, which in solution
forms carbonic acid.
Normal metabolic
operations produce
additional acids, such as
lactic acid.
Normal
plasma pH
(7.35–7.45)
Tissue cells
The kidneys play a major
role in acid-base balance
by secreting hydrogen
ions into the urine and
generating buffers that
enter the bloodstream.
The rate of excretion rises
and falls as needed to
maintain normal plasma
pH. As a result, the normal
pH of urine varies widely
but averages 6.0—slightly
acidic.
Buffer Systems
Buffer systems can
temporarily store hydrogen
ions and thereby provide
short-term pH stability.
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Figure 17 Section 5 1
pH Ranges (17.12)
• Normal pH of ECF 7.35–7.45
• Changes in H+ concentration are extremely
dangerous
• Alter stability of plasma membranes
• Alter structure of proteins
• Change activities of enzymes
• Nervous and cardiovascular systems are especially sensitive
to pH changes
• pH below 6.8 or above 7.7 quickly fatal
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Figure 17.12 11
Acidosis and Alkalosis (17.12)
•
Acidosis is a physiological condition
•
Caused by plasma pH below 7.35 (acidemia)
•
Severe acidosis is deadly
1. Central nervous system function deteriorates
2. Cardiac contractions are weak and irregular
3. Peripheral vasodilation causes severe drop in blood
pressure
•
Alkalosis is a physiological condition
•
Caused by plasma pH above 7.45 (alkalemia)
•
Severe alkalosis is dangerous but relatively rare
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Ranges of pH in ECF
The pH of the
ECF normally
ranges from
7.35 to 7.45.
When the pH of plasma falls
below 7.35, acidemia exists.
The physiological state that
results is called acidosis.
When the pH of plasma rises
above 7.45, alkalemia exists.
The physiological state that
results is called alkalosis.
Extremely
basic
Extremely
acidic
pH 0
1
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2
3
4
5
6
7
8
9
10
11
12
13
Figure 17.12 22
14
Carbon Dioxide and pH (17.12)
• Carbon dioxide level most important factor
affecting body pH
• Carbon dioxide (CO2) combines with water to form
carbonic acid (H2CO3)
• Inverse relationship between CO2 levels and pH
• Increased CO2 = decreased pH
• Decreased CO2 = increased pH
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Basic relationship between carbon dioxide and plasma pH
HOMEOSTASIS
If CO2 rises
When carbon dioxide levels rise, more carbonic acid
forms, additional hydrogen ions and bicarbonate ions
are released, and the pH goes down.
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If CO2 falls
When carbon dioxide levels fall, carbonic acid dissociates into water and carbon dioxide. This removes H+
ions from solution and increases the pH.
Figure 17.12 33
Buffer Systems (17.12)
• Temporarily compensate for shifts in pH by taking H+ ions
out of or releasing them into circulation
• Consists of combination of weak acid (HY) and the anion
(Y–) released by its dissociation
• Anion functions as weak base
• Weak acid and anion in equilibrium
• Adding H+ ions disrupts equilibrium with result being more weak
acid molecules (and less free H+)
• Removing H+ ions results in more dissociation (and more
free H+)
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Role of buffer system in body fluids
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Figure 17.12 44
Compensation (17.12)
• Buffer systems only temporarily compensate for
pH shifts
• Renal and respiratory systems can also
compensate
• Renal compensation
• Kidneys secrete or generate either H+ or HCO3–
• Respiratory compensation
• Respiratory rate increases or decreases controlling
rate CO2 is eliminated
© 2013 Pearson Education, Inc.
Module 17.12 Review
a. Define acidemia and alkalemia.
b. What is the most important factor affecting the pH
of the ECF?
c. Summarize the relationship between CO2 levels
and pH.
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Buffer Systems in the Body (17.13)
•
Three major buffer systems
1. Phosphate buffer system
2. Protein buffer systems
3. Carbonic acid–bicarbonate buffer system
•
These systems tie up H+ temporarily
•
Buffer molecules tied up as well
•
Limited supply of buffers
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Buffer systems in body fluids
Buffer systems
occur in
Extracellular fluid (ECF)
Intracellular fluid (ICF)
Phosphate buffer
system
Hemoglobin buffer
system (RBCs only)
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Carbonic acid–
bicarbonate buffer system
Protein buffer systems
Amino acid buffers
(all proteins)
Plasma protein
buffers
Figure 17.13 11
Hemoglobin Buffer System (17.13)
• Intracellular buffer system
• Can have immediate effect on pH of body fluids
• RBCs absorb carbon dioxide from plasma
• CO2 converted to carbonic acid
• Carbonic acid dissociates and hemoglobin proteins buffer
(attach to) hydrogen ions
• In lungs, process is reversed and CO2 is released
into alveoli
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Hemoglobin buffer system
Tissue
cells
Plasma
Red blood cells
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Lungs
Plasma
Red blood cells
Released
with
exhalation
Figure 17.13 22
Protein Buffer Systems (17.13)
• Amino acids respond to pH changes by accepting
or releasing H+
• Major groups available as buffers
• Carboxylate group (COO–) accepts additional hydrogen
ions forming a carboxyl group (–COOH)
• Amino group (–NH2) accepts additional hydrogen ions
forming an amino ion (–NH3+)
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Protein buffer systems
Start
Increasing acidity (decreasing pH)
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Normal pH
(7.35–7.45)
Figure 17.13 33
Carbonic Acid–Bicarbonate Buffer System
(17.13)
• Involves freely reversible reactions
• Protects against effects of acids generated by
metabolic activity
• Takes H+ and generates carbonic acid by combining H+ with
bicarbonate ion (HCO3–)
• Carbonic acid dissociates into water and carbon dioxide
• Bicarbonate reserves in body fluid in form of
sodium bicarbonate (NaHCO3)
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Carbonic acid–bicarbonate buffer system
CARBONIC ACID–BICARBONATE
BUFFER SYSTEM
Lungs
(carbonic acid)
Start
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(bicarbonate ion)
BICARBONATE RESERVE
(sodium bicarbonate)
Addition of H+
from metabolic
activity
Figure 17.13 44
Acid-Base Disorders (17.13)
• Metabolic acid-base disorders
• Result from production or loss of excessive amounts of acids
• Carbonic acid–bicarbonate buffer system protects against
these disorders
• Respiratory acid-base disorders
• Result from imbalance between CO2 generation and
elimination
• Carbonic acid–bicarbonate buffer system cannot protect
against respiratory disorders
• Imbalances must be corrected by change in depth and rate of
respiration
© 2013 Pearson Education, Inc.
Module 17.13 Review
a. Identify the body's three major buffer systems.
b. How do proteins and free amino acids act as
buffers when pH drops below normal?
c. Describe the carbonic acid–bicarbonate buffer
system.
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Metabolic Acidosis (17.14)
•
Develops when acids release large numbers of
hydrogen ions and pH drops
•
Responses to restore homeostasis involve:
1. Increased respiratory rate lowering CO2 levels,
converting more carbonic acid to water
2. Kidneys removing H+ from body fluids through
secretion
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Response to metabolic acidosis
Start
Addition
of H+
CARBONIC ACID–BICARBONATE BUFFER SYSTEM
Lungs
Respiratory Response
to Acidosis
Increased respiratory
rate lowers CO2 levels,
effectively converting
carbonic acid molecules
to water.
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(carbonic acid)
Other
buffer
systems
absorb H+
BICARBONATE RESERVE
(sodium bicarbonate)
(bicarbonate ion)
KIDNEYS
Generate
HCO3–
Renal Response to Acidosis
Secrete
H+
Kidney tubules respond by secreting H+
ions, removing CO2, and reabsorbing
HCO3– to help replenish the bicarbonate
reserve.
Figure 17.14 11
Respiratory Acidosis (17.14)
• Develops when rate of carbon dioxide removal by
lungs is less than carbon dioxide generation
• Responses to restore homeostasis involve:
• Increase in respiratory rate
• Increased H+ secretion by kidneys and generation of
HCO3– ions
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Response to respiratory acidosis
Slide 1
Increased
carbon dioxide
HOMEOSTASIS
DISTURBED
Hypoventilation
increases carbon dioxide
levels in blood
© 2013 Pearson Education, Inc.
Figure 17.14 22
Response to respiratory acidosis
Slide 2
Increased
carbon dioxide
Respiratory Acidosis
Elevated carbon
dioxide levels
decrease plasma pH
HOMEOSTASIS
DISTURBED
Hypoventilation
increases carbon dioxide
levels in blood
© 2013 Pearson Education, Inc.
Figure 17.14 22
Slide 3
Response to respiratory acidosis
Responses to Acidosis
Respiratory compensation
Stimulation of arterial and CSF
chemoreceptors raises
respiratory rate.
Renal compensation
Increased
carbon dioxide
Respiratory Acidosis
Elevated carbon
dioxide levels
decrease plasma pH
H+ ions are secreted and
HCO3– ions are generated.
Buffer systems other than the
carbonic acid–bicarbonate
system accept H+ ions.
HOMEOSTASIS
DISTURBED
Hypoventilation
increases carbon dioxide
levels in blood
© 2013 Pearson Education, Inc.
Figure 17.14 22
Slide 4
Response to respiratory acidosis
Responses to Acidosis
Respiratory compensation
Stimulation of arterial and CSF
chemoreceptors raises
respiratory rate.
Renal compensation
Increased
carbon dioxide
Respiratory Acidosis
Elevated carbon
dioxide levels
decrease plasma pH
H+ ions are secreted and
HCO3– ions are generated.
Buffer systems other than the
carbonic acid–bicarbonate
system accept H+ ions.
Combined Effects
Decrease carbon
dioxide levels
Decrease H+ and
increase HCO3–
HOMEOSTASIS
DISTURBED
Hypoventilation
increases carbon dioxide
levels in blood
© 2013 Pearson Education, Inc.
Figure 17.14 22
Slide 5
Response to respiratory acidosis
Responses to Acidosis
Respiratory compensation
Stimulation of arterial and CSF
chemoreceptors raises
respiratory rate.
Renal compensation
Increased
carbon dioxide
Respiratory Acidosis
Elevated carbon
dioxide levels
decrease plasma pH
HOMEOSTASIS
DISTURBED
Hypoventilation
increases carbon dioxide
levels in blood
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H+ ions are secreted and
HCO3– ions are generated.
Buffer systems other than the
carbonic acid–bicarbonate
system accept H+ ions.
HOMEOSTASIS
Normal acidbase balance
Combined Effects
Decrease carbon
dioxide levels
Decrease H+ and
increase HCO3–
HOMEOSTASIS
RESTORED
Start
Plasma pH
returns to normal
Figure 17.14 22
Metabolic Alkalosis (17.14)
•
Develops when large numbers hydrogen ions are
removed from body fluids, raising pH
•
Responses to restore homeostasis involve:
1. Decreased respiratory rate raising CO2 levels,
converting more CO2 to carbonic acid
2. Kidneys secrete less H+ from body fluids and excrete
more bicarbonate
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Response to respiratory alkalosis
Start
Removal
of H+
CARBONIC ACID–BICARBONATE BUFFER SYSTEM
BICARBONATE RESERVE
Lungs
Respiratory Response
to Alkalosis
Decreased respiratory
rate elevates CO2,
effectively converting
CO2 molecules to
carbonic acid.
© 2013 Pearson Education, Inc.
(carbonic acid)
(bicarbonate ion)
Other
buffer
systems
release H+
Generate
H+
(sodium bicarbonate)
KIDNEYS
Renal Response to Alkalosis
Secrete
HCO3–
Kidney tubules respond by
conserving H+ ions and
secreting HCO3–.
Figure 17.14 43
Respiratory Alkalosis (17.14)
• Develops when rate of carbon dioxide removal by
lungs exceeds carbon dioxide generation
• Often related to anxiety and hyperventilation
• Responses to restore homeostasis involve:
• Decrease in respiratory rate
• Decreased H+ secretion by kidneys and excretion of
HCO3– ions
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Response to respiratory alkalosis
Slide 1
HOMEOSTASIS
DISTURBED
Hyperventilation
decreases carbon dioxide
levels in blood
Decreased
carbon dioxide
© 2013 Pearson Education, Inc.
Figure 17.14 33
Response to respiratory alkalosis
Slide 2
HOMEOSTASIS
DISTURBED
Hyperventilation
decreases carbon dioxide
levels in blood
Respiratory Alkalosis
Lower carbon dioxide levels
raise plasma pH
Decreased
carbon dioxide
© 2013 Pearson Education, Inc.
Figure 17.14 33
Slide 3
Response to respiratory alkalosis
HOMEOSTASIS
DISTURBED
Hyperventilation
decreases carbon dioxide
levels in blood
Respiratory Alkalosis
Responses to Alkalosis
Lower carbon dioxide levels
raise plasma pH
Respiratory compensation
Decreased
carbon dioxide
Inhibition of arterial and CSF
chemoreceptors decreases
respiratory rate.
Renal compensation
H+ ions are generated and
HCO3– ions are secreted.
Buffer systems other than the
carbonic acid–bicarbonate system
release H+ ions.
© 2013 Pearson Education, Inc.
Figure 17.14 33
Slide 4
Response to respiratory alkalosis
HOMEOSTASIS
DISTURBED
Hyperventilation
decreases carbon dioxide
levels in blood
Respiratory Alkalosis
Responses to Alkalosis
Combined Effects
Lower carbon dioxide levels
raise plasma pH
Respiratory compensation
Increase carbon dioxide levels
Decreased
carbon dioxide
Inhibition of arterial and CSF
chemoreceptors decreases
respiratory rate.
Increase H+ and decrease
HCO3–
Renal compensation
H+ ions are generated and
HCO3– ions are secreted.
Buffer systems other than the
carbonic acid–bicarbonate system
release H+ ions.
© 2013 Pearson Education, Inc.
Figure 17.14 33
Slide 5
Response to respiratory alkalosis
HOMEOSTASIS
HOMEOSTASIS
DISTURBED
Start
Normal acidbase balance
Hyperventilation
decreases carbon dioxide
levels in blood
HOMEOSTASIS
RESTORED
Plasma pH
returns to normal
Respiratory Alkalosis
Responses to Alkalosis
Combined Effects
Lower carbon dioxide levels
raise plasma pH
Respiratory compensation
Increase carbon dioxide levels
Decreased
carbon dioxide
Inhibition of arterial and CSF
chemoreceptors decreases
respiratory rate.
Increase H+ and decrease
HCO3–
Renal compensation
H+ ions are generated and
HCO3– ions are secreted.
Buffer systems other than the
carbonic acid–bicarbonate system
release H+ ions.
© 2013 Pearson Education, Inc.
Figure 17.14 33
Module 17.14 Review
a. Compare metabolic acidosis and metabolic
alkalosis.
b. Compare respiratory acidosis and respiratory
alkalosis.
c. If the kidneys are conserving HCO3– and
eliminating H+ in urine, to which condition are the
kidneys responding?
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