Download 022 Urinary System

The Urinary System
Function
1. Remove nitrogenous wastes
2. Maintain electrolyte, acid-base,
and fluid balance of blood
3. Homeostatic organ
4. Acts as blood filter
5. Release hormones: calcitriol &
erythropoietin
Kidneys as Filters
• Diuretic- loose water; coffee, alcohol
• Antidiuretic- retain water; ADH
• Aldosterone- sodium & water reabsorption,
and K+ excretion
• GFR= 180 liters (50 gal) of blood/day
• 178-179 liters are reabsorbed back into
blood
• Excrete a protein free filtrate
Maintaining
Chemical
Homeostasis
The
Urinary
System
The Urinary System
blood
filtration
General
Functioning
of the Kidney
tubular
reabsorption
and secretion
urine “refreshed” blood
Nitrogenous
Wastes
urea
uric acid
ammonia
kidneys
Organs
of the
Urinary
System
ureters
urinary
bladder
urethra
Kidney
Anatomy
renal
pelvis
ureter
renal
pyramids
renal
cortex
renal
capsule
renal
medulla
nephron
renal artery
renal vein
Kidney
Anatomy
blood
Nephron
Functioning
filtration
tubular
reabsorption
and secretion
urine “refreshed” blood
efferent
arteriole
afferent
arteriole
glomerulus
artery
peritubular
capillaries
loop of
Henle
vein
Bowman’s
capsule
proximal
convoluted
tubule
distal
convoluted
tubule
collecting
duct
Each kidney contains over 1 million nephrons and thousands
of collecting ducts
Glomerulus
DCT
renal
cortex
PCT
renal
medulla
Collecting duct
Loop of Henle
efferent
arteriole
afferent
arteriole
Glomerular
Filtration
Bowman’s
capsule
Filters blood; proteins can’t pass through
glomerulus
Composition of
Glomerular Filtrate
• Water
• Small Soluble Organic
Molecules
• Mineral Ions
Proximal Convoluted
Tubule
Reabsorbs: water, glucose,
amino acids, and sodium.
•
•
•
•
65% of Na+ is reabsorbed
65% of H2O is reabsorbed
90% of filtered bicarbonate (HCO3-)
50% of Cl- and K+
Loop of Henle
Creates a gradient of increasing
sodium ion concentration towards
the end of the loop within the
interstitial fluid of the renal pyramid.
• 25% Na+ is reabsorbed in the loop
• 15% water is reabsorbed in the loop
• 40% K is reabsorbed in the loop
Distal Convoluted
Tubule
Under the influence of the hormone
aldosterone, reabsorbs sodium and
secretes potassium. Also regulates
pH by secreting hydrogen ion when
pH of the plasma is low.
• only 10% of the filtered NaCl and 20% of water
remains
Collecting Duct
Allows for the osmotic
reabsorption of water.
ADH (antidiuretic hormone)- makes
collecting ducts more permeable to
water-- produce concentrated urine
Urine
Water- 95%
Nitrogenous waste:
• urea
• uric acid
• creatinine
Ions:
• sodium
• potassium
• sulfate
• phosphate
From the original 1800 g NaCl, only 10 g appears in
the urine
Hormonal
Control of
Kidney
Function
Hormonal Control
of Kidney Function
high plasma
solute
concentration
low blood volume
heart receptors
hypothalamus
Hormonal Control
of Kidney Function
hypothalamus
posterior pituitary
antidiuretic hormone
collecting ducts
Hormonal
Control of
Kidney
Function
Hormonal Control
of Kidney Function
reduced blood pressure and
glomerular filtrate
juxtaglomerular apparatus
renin
Hormonal Control
of Kidney Function
angiotensinogen
angiotensin I
angiotensin II
renin
Hormonal Control
of Kidney Function
angiotensin II
adrenal cortex
aldosterone
convoluted tubules
Urinary Bladder
ureters
external
sphincters
internal
sphincters
urethra
Bladder
1. Mucosa (transitional epithelium)
2. Muscular layer (detrusor muscle):
3 layers of smooth muscle
3. Fibrous adventia
Sphincter Muscles on Bladder
Internal urethral sphincter:
• Smooth muscle
• Involuntary control
• More superiorly located
External Urethral sphincter:
• Skeletal muscle
• Voluntary control
• Posteriorly located
Diuresis (Micturition)
When bladder fills with 200 ml of urine,
stretch receptors transmit impulses to
the CNS and produce a reflex
contraction of the bladder (PNS)
When is incontinence normal?
Distension
of the
Urinary
Bladder
Urinalysis
Why do doctors ask for a urine sample?
characteristics:
• smell- ammonia-like
• pH- 4.5-8, ave 6.0
• specific gravity– more than 1.0; ~1.0011.003
• color- affected by what we eat: salty foods,
vitamins
Odor
odor- normal is ammonia-like
diabetes mellitus- smells fruity or
acetone like due to elevated ketone
levels
diabetes insupidus- yucky
asparagus---
pH- range 4.5-8 ave 6.0
vegetarian diet- urine is alkaline
protein rich and wheat dieturine is acidic
Color
Color- pigment is urochrome
Yellow color due to metabolic breakdown of
hemoglobin (by bile or bile pigments)
Beets or rhubarb- might give a urine pink or
smoky color
Vitamins- vitamin C- bright yellow
Infection- cloudy
Specific Gravity
Water: s.g. = 1g/liter;
Urine: s.g. ~ 1.001 to 1.030
Pyelonephritus- urine has high s.g.;
form kidney stones
Diabetes insipidus- urine has low
s.g.; drinks excessive water; injury or
tumor in pituitary
Abnormal Constitutes of Urine
Glucose- when present in urine condition
called glycosuria (nonpathological)
[glucose not normally found in urine]
Indicative of:
• Excessive carbohydrate intake
• Stress
• Diabetes mellitus
Abnormal Constitutes of Urine
Albumin-abnormal in urine; it’s a very large
molecule, too large to pass through glomerular
membrane > abnormal increase in permeability
of membrane
Albuminuria- nonpathological conditionsexcessive exertion, pregnancy, overabundant
protein intake-- leads to physiologic albuminuria
Pathological condition- kidney trauma due to
blows, heavy metals, bacterial toxin
Abnormal Constitutes of Urine
Ketone bodies- normal in urine but in small amts
Ketonuria- find during starvation, using fat stores
Ketonuria is couples w/a finding of glycosuria-- which
is usually diagnosed as diabetes mellitus
RBC-hematuria
HemoglobinHemoglobinuria- due to fragmentation or hemolysis of
RBC; conditions: hemolytic anemia, transfusion
reaction, burns or renal disease
Abnormal Constitutes of Urine
Bile pigmentsBilirubinuria (bile pigment in urine)- liver pathology such as
hepatitis or cirrhosis
WBCPyuria- urinary tract infection; indicates inflammation of
urinary tract
Casts- hardened cell fragments, cylindrical, flushed out of
urinary tract
WBC casts- pyelonephritus
RBC casts- glomerulonephritus
Fatty casts- renal damage
INQUIRY
1.
2.
3.
4.
5.
List several functions of the kidneys.
What does the glomerulus do?
What are several constitutes you should not find in urine?
What is specific gravity?
What two hormones effect fluid volume and sodium
concentration in the urine?
6. Where are the pyramids located in the kidney?
7. What vessel directs blood into the glomerulus?
8. Where does most selective reabsorption occur in the
nephron?
Moment of Zen
KIDNEY