Urinary Drill
Name the functions of the excretory system.
What is the functioning unit of the kidney?
How many are there per kidney?
Urinary Drill
1. List & describe the steps for urine
2.
3.
4.
5.
formation.
What is the renal corpuscle made of?
What are the parts of the convoluted
tubule?
What are the name of the cells that open
and close in the glomerulus?
What controls the podocytes?
Urinary Drill
1. What is the driving force of filtration and
secretion?
2. How big is your kidney? Why is the right
kidney lower that the left kidney?
3. Where does urea and uric acid come
from?
4. How does Aldosterone and Atrial
Natriuretic Factor effect urine formation?
1. What is the function of the kidneys?
2. What is the function of the ureters?
3. What is the function of the urinary
bladder?
4. Why are the uretherea, bladder, and
ureter coated with mucus?
Urinary System
Function
1. Excretion
2. Regulation of blood volume and pressure.
3. regulation of the concentration of solutes in
the blood.
4. Regulation of extracellular fluid pH.
5. Vitamin D synthesis.
I. Kidney Structure
A. External
1. Size of your fist.
2. Kidney bean shaped.
3. Right kidney is slightly lower
than the left, due to
liver.
4. Renal Fascia - anchors
kidney & adrenal gland to
surrounding tissues.
5. Adipose Capsule - Cushion
layer.
6. Renal Capsule - thin,
transparent layer of fibrous
tissue.
B. Internal
1. Renal medulla - inner most.
a. Hilum - Concave portion where the renal artery &
vein unit with the kidney.
b. Renal sinus - space.
c. Renal pelvis - membrane line basin.
d. Calyces - funnel shaped channels from the pelvis &
collects newly formed urine.
2. Renal Cortex - Outermost layer
3. Renal Pyramids
4. Renal Columns - Parts of the cortex extends into the
medulla.
5. Nephrons - functional subunit of the kidney.
Kidney Structure
C. Blood Supply - 1200ml/min @ rest.
To the nephron
From the nephron
1. Renal artery
7. Efferent Arterioles
2. Lobar Arteries - 5 in the renal sinuses
8. Interlobular Veins
3. Interlobar Arteries - renal pyramids
9. Arcuate Veins
4. Arcuate Arteries - Between Cortex & medulla
10. Interlobar Veins
5. Interlobular Arteries - Cortex
11. Lobar Veins
6. Afferent Arterioles - to nephron
12. Renal Veins
Blood Supply to Kidney
D. Nephron Structure - 1 million/kidney
A portion is in both the medulla & cortex
Two parts
a. Renal Corpuscle
1. Bowman Capsule
2. Glomerulus
a. Fenestrae - pore in endothelial walls of glomerulus.
b. Podocytes - specialized cells.
c. Filteration slits
b. Renal Tubule - Series of single layer tubules
1. Proximal Convoluted tubule
2. Loop of Henle
3. Distal Convoluted tubule
E. Blood Flow Through Nephron
Blood
Afferent - Large ->
Glomerulus - Narrow & creates
high back pressure
Efferent
Blood <- Peritubular Tubulars porus & low pressure
Nephron
F. Juxtaglomerular
Apparatus
1. Distal convoluted
tubular contacts the
afferent arteriole.
2. Regulates the rate of
urine formation.
II. Kidney Function
Removal of unwanted
substances (through excretion
- urea & uric acid) from the
blood stream & maintain a fluid
balance electrolyte
concentration, & pH.
A. Urine formation
180 L (145 gallons)/day - 35
time your total blood volume.
99% of the fluid is returned to
the blood stream.
1% 1-2 L is excreted as urine.
3 step process
1. Filtration - movement of blood
plasma across the filtration membrane
at the renal corpuscle.
a. Filtrate - fluid & dissolved
substances that penetrate
the membrane.
b. High hydrostatic pressure at
the glomerulus (glomerular
capillary pressure) pushes plasma
through the filtration membrane.
c. Net Filtration pressure
(NFP) 10mm of mercury.
d. Rate of filtration is
determined by filtration that is
present.
High filtration pressure= high
volume of filtrate
Reabsorbtion
2. Reabsorption
a. 99% of water, majority of nutrients, essential ions are
removed & transported to nearby peritubular
capillaries.
 K+, Ca+, HCO3-, Cl-
b. Reclaiming of material is returned to the blood stream
resulting in a concentration of wastes that remain in the
tubule.
c. Filtrate vs urine
Filtrate - Same as blood plasma except the lack of
proteins.
Urine - more concentration of ions, urea, & uric acid
d. Reabsorption procedure
Proximal Convoluted Tubule 65% of reabsorption.
Main site of water & solute reabsorbtion.
Reabsorption in the Proximal
Tubule
Urine Substances
3. Loop of Henle 15% of
reabsorption.
Descending - continues
water reabsorption
Solute concentration
increases
Ascending - Reabsorption
of solutes (Chloride,
sodium)
More dilute because of
the removal of solutes.
Ascending Reabsorption of
solutes (Chloride,
sodium)
More dilute
because of the
removal of solutes.
Reasorption
in Distal
tubule
collecting
dcut
4. Secretion - Net movement of unwanted
substance from the peritubular capillaries
into the proximal convoluted.
How does this movement occur?
Active transport - H ions (controls the
body’s pH), Potassium ions, Penicillin)
Diffusion – urea
Facilitated diffusion
III. Urea & Uric Acid Formation
Nitrogen containing wastes products from cellular metabolism
A. Urea
Liver’s metabolism of AA creates ammonia (toxic), so it is
quickly converted to urea by the liver & released in to the
bloodstream.
50% is excreted in urine/50% is reabsorbed by the body.
B. Uric Acid
Metabolism of certain nucleic acids.
10% is removed by urine
IV. Regulation of Urine Concentration & Volume
Fluctuates in response to our changing condition
of our body to maintain a constant blood
composition & volume.
Large salty meal -Increases slat in urine &
increase urine volume.
After exercise - Urine volume is less with less salt.
Juxtaglomerular regulates urine formation & is
triggered when NFP decreases.
A. Renin & Angiotensin – Increases water reabsorption.
Renin converts a plasma protein to Angiotensin.
Angiotensin is then converted in the blood into
Angiotensin II.
Angiotensin II effects the adrenal Cortex to
release Aldosterone which increases reabsorption of Sodium, Chloride, water (increases
blood pressure).
Increases in blood pressure, increases NFP,
increased in filtrate production.
B. Aldosterone-Increases water re-absorption.
Released by the Adrenal Gland
Regulates rate of active transport in the distal
convoluted tubule & collecting duct.
Increases the re-absorption of sodium by
transporting it out.
Water follows because of the concentration
gradient.
Volume of urine decreases, increase in blood
pressure.
C. Antidiuretic Hormone (ADH) - Posterior Pituitary Gland.
Increases water re-absorption.
Increases in blood volume - Pituitary releases ADH.
Increases the permeability of distal tubules & collecting
ducts to water.
Water absorption increases, therefore blood volume
increases.
Increase in urine concentration.
D. Atrial Natriuretic Factor- decreases water re-absorption
Released by the cells in the right atrium of the heart when
blood pressure changes within the heart.
Reduces the ability of the kidneys to reabsorb water &
solutes, resulting in a large volume of urine, therefore blood
pressure decreases.
E. Sympathetic Stimulation- Decreases water
reabsorption
Nerve impulses from the sympathetic nervous
system stimulate the contraction of smooth
muscle in the wall of afferent arterioles.
Vasconstriction results in decreased in blood flow
passing through the glomerulus.
Decreased in NFP.
Decreased in filtrate & urine volume.
From heavy exercise or excitement.
Hormonal
regulation
overview
V. Maintenance of Body Fluids
Uptake of water & electrolytes = removal.
Organs involved
Skin, liver, organs of the alimentary canal, &
kidney (largest effect).
VI Regulation of pH
7.35 - 7.45 are normal ranges
Low pH Acidosis (respiratory or metabolic) high pH
Alkalosis (respiratory or metabolic).
A. Buffers. Resist changes in pH.
Three main buffers
Proteins
Phosphates
Bicarbonate - most important because it
regulates the respiratory & urinary system.
H20 + CO2 <-> H2CO3 <-> H+ + HCO3
In blood
Carbonic anhydrase
B. Respiratory System
(+) CO2, (-) pH, brain increases in deep breathing
- more CO2 exhaled pH(+).
(-) CO2, (+) pH, brain decreases breathing, less
CO2 leaves, CO2 builds up in tissues, (+)H ,(-) pH
.
C. Kidney
(-) pH, increases the rate of secretion of H @ the
same time rate of reabsorbtion of bicarbonate
ions.
Excess H are removed & restoring the pH.
(+) pH reduces rate of H secretion & bicarbonate
reabsorbtion
Lower pH.
Regulation of pH
Regulation of Potassium
Regulation of Calcium
VII Ureters
A. Carries newly formed urine
from the kidneys to the urinary
bladder.
B. Pair tubular organ designed
for transport.
C. Arise from the renal pelvis.
D. Extend downward along the
vertebral column.
E. Behind the peritoneum
(retroperitoneal).
E. Wall of each ureter as three
layers.
1. Inner - mucus
membrane, protects
underlying cells from the
passage of urine.
2. Middle -Smooth muscle
& elastic fibers, peristaltic
contraction.
3. Outer - fibrous
connective tissue that
protects the underlying
tissue.
F. Flap at each opening that
acts as a one way valve.
IIX Urinary Bladder
A. Is an expandable saclike like
organ that receives urine from
the ureters & stores it until
release into the urethra.
B. Located on the floor of the
pelvis behind the symphysis.
C. Top surface is only covered
by peritoneum.
D. Walls are extremely elastic.
E. Average capacity of 500 ml,
but it can hold twice that.
F. Ureteral openings.
G. Trigone - frequent site of
urinary infections.
H. Walls of the bladder is
made up of four layers:
1. Innermost –
mucous
2. Connective supportive.
3. Smooth muscle,
Detrusor muscle longitudinal & circular
layers of fibers.
4. Fibrous connective
tissue.
IX Urethra
A. Transports urine from the
urinary bladder to the exterior,
differs between males &
females.
B. Internal urethral sphincter smooth muscle, involuntary
keeps urine in the bladder.
C. External urethral sphincter skeletal muscle – voluntary
1. Males
a. 8 inches long
b. Passes
through the
prostate.
c. Carries
reproductive fluids.
2. Females
a. 1.5 inches long
X. Micturition (voluntary control between 23)
A. Process of emptying the bladder & is
both a voluntary & involuntary response.
B. 200 ml, bladder wall stretches to
activate the stretch receptors.
C. Send a signal to the spinal cord.
D. Motor signal are sent to the bladder by
a reflex arc.
E. Detrusor muscle to contract & internal
urethral sphincter to relax.
F. As detrusor continues to contract,
increase urge to void.
G. Maybe stopped by the exterior
urethral sphincter if timing is not
appropriate.
H. Further contraction of the detrusor
XI Problems with the Urinary System
A. Anuria - absence of urine due to kidney failure or
obstruction
B. Claculi - kidney stones due to increased salts in urine.
Uric acid crystals that precipitate out of the blood
stream & build up in the lower gut.
Excess of calcium salts.
C. Cystitis - Inflammation of the urinary bladder due to
entry of a bacteria through the urethera.
D. Hematuria - Presence of blood in the urine caused by
cuts in the urinary tract
E. Renal Failure & Dialysis
1. loss of the kidney’s ability to respond to changes in the
body.
2. rapid loss of fluid, electrolytes.
3. build up of wastes
Acute - abrupt stoppage, temporary.
4. Pain, Reduce urine output, bleeding.
5. Injury, infection, drugs.
6. Chronic - progressive loss of kidney function because of
reduced glomerular function.
7. Build of urea in blood, pH imbalance, electrolytes
imbalance.
8. Kidney failure - no formation of urine, result in rapid build.
of of toxic wastes, & acidic pH - death in 8 - 10 days.
9.Kidney transplant or dialysis - 3 times a week.
Dialysis
XII Testing for
healthy kidneys
A. Urinalysis analysis of
chemical content
of a urine sample