Download Urinary System Anatomy Waste Urinary System Urinary System

4/22/2016
Waste
Urinary System Anatomy
Urinary Section pages 5-8
• Metabolism produces waste products
• What is the primary waste product of cellular
respiration? How does the body dispose of it?
Urinary System
•
•
•
•
Disposes of water soluble wastes
Maintains fluid balance
Regulates electrolytes
Regulates acid-base balance
Urinary System
• Other functions
– Kidneys
• Renin stored and secreted
– Enzyme involved in
angiotensin II activation
• Erythropoietin
– Hormone that stimulates
RBC production
• Vitamin D activation
– Enzymes convert dietary and
manufactured vitamin D to
calcitrol
Nitrogenous Wastes
Nitrogenous Wastes
TOXIC!
• Urine is about 95% water
• Second largest component is urea
– Urea derived from breakdown of amino acids
1. Dietary amino acids → NH2 removed → NH2 + H+ → NH3
– 500 ml of urine removes only 1 gram of nitrogen as ammonia
2. Ammonia can be converted to urea
– Requires energy
– 50 ml of urine removes 1 gram of nitrogen as urea
3. Ammonia can be converted to uric acid
– Requires lots of energy
– 10 ml of urine removes 1 gram of nitrogen as uric acid
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Fill in the blanks…
Urinary System
• Organs
Ammonia
Toxicity
Urea
• Major excretory organs
Energy Costs
– Urinary bladder
High = 3 ATP
Water Required
50 ml/g Nitrogen
Solubility
Examples
– Kidneys
Uric acid
Very toxic
• Temporary storage reservoir for urine
Low
– Ureters
Fish & aquatic
invertebrates
• Transport urine from the kidneys to the bladder
– Urethra
• Transports urine out of the body
Hepatic veins (cut)
Esophagus (cut)
Inferior vena cava
Renal artery
Adrenal gland
Anterior
Renal hilum
Inferior vena cava
Renal vein
Aorta
Kidney
Iliac crest
Peritoneum
Ureter
Rectum (cut)
Uterus (part
of female
reproductive
system)
Peritoneal cavity
(organs removed)
Renal
vein
Renal
artery
Body wall
(a)
Urethra
Posterior
Figure 25.1
Figure 25.2a
Kidneys
• External anatomy
– Retroperitoneal position
– Embedded in pararenal fat
Supportive
tissue layers
• Renal fascia
anterior
posterior
• Perirenal
fat capsule
• Fibrous
capsule
Body of
vertebra L2
Urinary
bladder
Aorta
Kidneys
• External anatomy
– Hilus (or hilum)
• Where blood vessels, nerves,
and ureter pass
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Kidneys
• External anatomy
– 3 tissue layers surround & support
• Fibrous capsule
• Perirenal fat capsule
• Renal fascia
Hydronephrosis
• Backup of urine causes excess fluid in the
kidney
• Common causes
– Kidney stones
– Infection
– Enlarged prostate
– Blood clot
– Tumor
Kidneys
Kidneys
– Renal medulla
• Internal Anatomy
– Renal cortex
• Superficial region
• Renal columns extend into medulla
• Where urine is produced
• Cone-shaped medullary (renal)
pyramids
• Separated by the renal
columns
• Consist of tubules that
transport urine to the
calyces
Kidneys
Kidneys
– Renal pelvis
– Renal medulla
• The papilla (point) of each
pyramid drains into a
minor calyx
• Several minor calyces
drain into one major calyx
• Major calyces drain into
renal pelvis
• Funnel-shaped tube that collects
urine from calyces
• Continuous with ureter
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Kidneys
Renal
hilum
Renal cortex
• Blood Supply
Renal medulla
– Renal arteries deliver ~ 22 % of cardiac output (1.2
L/min)
Major calyx
Papilla of
pyramid
Renal pelvis
• 90% directed to cortex
• Urine formation
Minor calyx
Ureter
Renal pyramid
in renal medulla
Renal column
Fibrous capsule
(a) Photograph of right kidney, frontal section
(b) Diagrammatic view
Figure 25.3
Aorta
Cortical radiate vein
Cortical radiate artery
Arcuate vein
Arcuate artery
Interlobar vein
Interlobar artery
Segmental arteries
Renal vein
Renal artery
Segmental artery
Interlobar vein
Arcuate vein
Arcuate artery
Cortical radiate
vein
Cortical radiate artery
Peritubular
capillaries
and vasa recta
Renal pelvis
Afferent arteriole
Renal medulla
Renal vein
Interlobar artery
Renal artery
Ureter
Inferior vena cava
Efferent arteriole
Glomerulus (capillaries)
Nephron-associated blood vessels
(see Figure 25.8)
(b) Path of blood flow through renal blood vessels
Renal cortex
(a) Frontal section illustrating major blood vessels
Figure 25.4a
Figure 25.4b
Nephrons
•
•
•
Structural and functional units that form
urine
~1 million per kidney
Two main parts
1. Blood capillaries (glomeruli)
2. Renal tubule: begins as cup-shaped glomerular
(Bowman’s) capsule surrounding the glomerulus
Figure 25.5
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Nephrons
Nephrons
• Renal corpuscle
• Glomerular endothelium
– Glomerulus + Bowman’s capsule
Efferent
arteriole
– Fenestrated capillary endothelium
– Layer of highly branched and interlaced podocytes
– Allows filtrate to pass from plasma into the
glomerular capsule
Glomerular capsule
Glomerulus
Afferent
arteriole
Parietal layer
of glomerular
capsule
Capsular
space
Foot processes
of podocytes
Podocyte cell
body (visceral
layer)
Red blood cell
Proximal
tubule cell
Efferent
arteriole
Cortical nephron
• Has short loop of Henle and glomerulus
further from the corticomedullary junction
• Efferent arteriole supplies peritubular
capillaries
Efferent arteriole
Glomerular capillaries
Renal
corpuscle (glomerulus)
Glomerular
(Bowman’s) capsule
Proximal
convoluted tubule
Peritubular capillaries
Juxtaglomerular
apparatus
Cortex
Medulla
Renal pelvis
Ureter
• Macula densa cells
Lumens of
glomerular
capillaries
Endothelial cell
of glomerular
capillary
Mesangial cells
between capillaries
• Extraglomerular
mesangial cells
• Granular cells
Afferent arteriole
Juxtaglomerular
apparatus
Renal corpuscle
Loop of Henle
Juxtamedullary nephron
• Has long loop of Henle and glomerulus
closer to the corticomedullary junction
• Efferent arteriole supplies vasa recta
Afferent arteriole
Collecting duct
Distal convoluted tubule
Afferent arteriole
Efferent arteriole
Corticomedullary
junction
Vasa recta
loop of Henle
Kidney
(a)
Figure 25.8
Figure 25.7a
Nephrons
• Renal tubules
– Proximal convoluted tubule (PCT)
• So-called because it is proximal to renal corpuscle
• Functions
– Major site of reabsorption (amino acids, glucose, water, Na+)
– Secretion (medications, nitrogenous wastes)
– Exchange of ions important for pH (H+, HCO3-)
Nephrons
• Renal tubules
– Loop of Henle
• Descends from the cortex to the medulla, turns, and comes
back to the cortex
• More later…
• Confined to the cortex
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Nephrons
Nephrons
• Renal tubules
• Renal tubules
– Distal convoluted tubule (DCT)
– Collecting tubules (CT)
• Important site for secretion, aldosterone & ADH
activity
• Exchange of ions important for pH (H+, HCO3-)
• Reabsorption of some electrolytes such as Na+
• Confined to the cortex
• Receive filtrate from many nephrons
• Fuse together to deliver urine through papillae into
minor calyces
• Functions
– Important site for secretion, aldosterone & ADH activity
– Site of reabsorption of water and electrolytes
– Exchange of ions important for pH (H+, HCO3-)
Nephrons
Glomerular capsule: parietal layer
Renal cortex
Basement
membrane
Renal medulla
Renal corpuscle
• Glomerular capsule
• Glomerulus
Renal pelvis
Podocyte
Distal
convoluted
tubule
Ureter
Kidney
Fenestrated
endothelium
of the glomerulus
Glomerular capsule: visceral layer
Microvilli
Mitochondria
Proximal
convoluted
tubule
Highly infolded plasma
membrane
Proximal convoluted tubule cells
Cortex
– Distal convoluted tubule and afferent arteriole
contact one another – modified at the point of
contact
• One per nephron
– Function
Medulla
Thick segment
Thin segment
Loop of Henle
• Descending limb
• Ascending limb
• Juxtaglomerular Apparatus (JGA)
Distal convoluted tubule cells
Collecting
duct
• Regulation of filtrate formation and blood pressure
Loop of Henle (thin-segment) cells
Principal cell
Intercalated cell
Collecting duct cells
Figure 25.5
Nephrons
• Juxtaglomerular Apparatus (JGA)
– 3 components
1) Macula densa
• Group of columnar cells on DCT
• Chemoreceptors that monitor NaCl
content of filtrate entering DCT
• Sense DCT flow and release
chemicals that alter diameter
of afferent arteriole
Nephrons
• Juxtaglomerular Apparatus (JGA)
– 3 components
2) Granular cells
• AKA juxtaglomerular cells
• In wall of afferent arteriole
• Enlarged smooth muscle cells
• Mechanoreceptors that sense blood
pressure in afferent arteriole
• Store and secrete renin in response
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Nephrons
Efferent
arteriole
Glomerular capsule
Glomerulus
Afferent
arteriole
Parietal layer
of glomerular
capsule
Capsular
space
• Juxtaglomerular Apparatus (JGA)
– 3 components
3) Extraglomerular mesangial cells
• Lie between arteriole and DCT
• Connected by gap junctions
• Pass regulatory signals between
macula densa and granular cells
Foot processes
of podocytes
Podocyte cell
body (visceral
layer)
Red blood cell
Proximal
tubule cell
Efferent
arteriole
Juxtaglomerular
apparatus
• Macula densa cells
Lumens of
glomerular
capillaries
Endothelial cell
of glomerular
capillary
Mesangial cells
between capillaries
• Extraglomerular
mesangial cells
• Granular cells
Afferent arteriole
Juxtaglomerular
apparatus
Renal corpuscle
Figure 25.8
Nephron Capillary Beds
1. Glomerulus
– Afferent arteriole → glomerulus → efferent
arteriole
– Specialized for filtration
Nephron Capillary Beds
2. Peritubular capillaries
– Low-pressure, porous capillaries adapted for
absorption
– Arise from efferent arterioles
– Cling to adjacent renal tubules in cortex
– Empty into venules
Nephrons
• Cortical nephrons
– 85% of nephrons; almost entirely in the cortex
• Short loops of Henle extend barely into medulla
• Juxtamedullary nephrons
– Long loops of Henle deeply invade the medulla
– Extensive thin segments
– Important in the production of concentrated urine
• Much more on this later…
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Ureters
Urinary Bladder
• Muscular sac for temporary storage of urine
• On pelvic floor posterior to pubic symphysis
• Convey urine from kidneys to bladder
• Retroperitoneal location
• Enter base of bladder through posterior wall
– Males—prostate gland surrounds the neck
inferiorly
– Females—anterior to the vagina and uterus
– ↑ bladder pressure = distal ends of the ureters
close
• Prevents backflow of urine
– Mucus is protective
Urinary Bladder
Urinary Bladder
– Stretch receptors in bladder create desire to void
– Epithelium is specialized to accommodate
stretching and recoil as bladder fills and empties
• Micturition
• Urge to void usually occurs with about 300ml urine
• Can hold up to about 500ml
Urethra
Hepatic veins (cut)
Esophagus (cut)
Inferior vena cava
Adrenal gland
Renal artery
Renal hilum
Aorta
Renal vein
Rectum (cut)
Uterus (part
of female
reproductive
system)
• Internal
– ANS control
• External
Kidney
Iliac crest
– Sphincters
– Voluntary control
Ureter
Urinary
bladder
Urethra
Figure 25.1
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Peritoneum
Ureter
Rugae
Detrusor muscle
Adventitia
Ureteric orifices
Trigone of bladder
Bladder neck
Internal urethral sphincter
Prostate
Prostatic urethra
Urogenital diaphragm
External urethral sphincter
Membranous urethra
Peritoneum
Ureter
Rugae
Detrusor
muscle
Ureteric orifices
Bladder neck
Internal urethral
sphincter
External urethral
sphincter
Urogenital diaphragm
Trigone
Urethra
External urethral
orifice
(b) Female.
Spongy urethra
Erectile tissue of penis
External urethral orifice
(a) Male. The long male urethra has three
regions: prostatic, membranous and spongy.
Figure 25.21b
Incontinence
Brain
Higher brain
centers
Urinary bladder
filling stretches
bladder wall
Allow or inhibit micturition
as appropriate
Pontine micturition
center
Afferent impulses
from stretch
receptors
• Damage to spinal cord
• Frequent micturition in infants
Pontine storage
center
Promotes micturition
by acting on all three
spinal efferents
Simple
spinal
reflex
Inhibits micturition
by acting on all three
spinal efferents
Spinal
cord
Spinal
cord
Parasympathetic
activity
Figure 25.21a
Sympathetic
activity
Detrusor muscle
contracts; internal
urethral sphincter
opens
Somatic motor
nerve activity
– Incontinence is normal: control of the voluntary
urethral sphincter develops with the nervous
system
Parasympathetic activity
Sympathetic activity
Somatic motor nerve activity
External urethral
sphincter opens
Inhibits
Micturition
Figure 25.22
Pathway of Urine Flow
Urine formed in nephrons
Calyces
Renal pelvis
Ureters
Bladder
Urethra
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