Exercise 9:
Renal System
Physiology
Hina Rehmani
Exercise 9:
Renal System
Physiology
Hina Rehmani
Structure and Function of the
Kidney
Wastes produced by metabolism need
to be removed by the body
Kidney is made up of about 1 million
Nephrons
Function of the Kidney
Blood Filtration
Fluid Processing
Structure and Function of the
Kidney
Nephrons are microscopic tubules composed of:
Glomerulus
Renal Tubule
Glomerulus is a tangled capillary bed
Filters fluid from blood into the Renal Tubule
Glomerular Filtration: Fluid moves passively out of
Glomerulus
Renal Tubule is a long tube
Processes the filtrate from the Glomerulus
Tubular Reabsorption: Reabsorbs useful substances
Tubular Secretion: Move wastes towards elimination
Structure and Function of the
Kidney
The Renal Tubule consists of:
Proximal Convoluted Tubule (PCT)
Loop of Henle (Nephron Loop)
Distal Convoluted Tubule (DCT)
Collecting Duct
Last part of the collecting tubule in the nephron
Glomerular capsule surrounds the Glomerulus
Funnels filtrate into the Renal Tubule
Renal corpuscle
Name for the Glomerulus and Glomerular capsule
collectively
Structure and Function of the
Kidney
Blood Supply to the Glomerulus
Afferent Arteriole
Feed the Glomerular Capillary Bed
Efferent Arteriole
Drains the Glomerular Capillary Bed
Stimulating Glomerular
Filtration
Efferent
Afferent
Glomerulu
s
Glomerula
r capsule
PCT
Loop of
Henle
DCT
Collectin
g Duct
Activity 1: Effect of Flow Tube
Radius on Glomerular Filtration
Procedure: Increase the Afferent Arteriole radius
by 0.05 mm increments
What happens to the Glomerular Filtration Rate as
the Afferent radius increases?
It increases!
What would happen to the Glomerular Filtration
Rate if the Efferent radius was increased or
decreased?
If increased then Glomerular Filtration Rate would
decrease
If decreased then Glomerular Filtration Rate would
increase
Activity 2: Effect of Pressure on
Glomerular Filtration
Procedure: Increase the blood pressure
supplying the Glomerulus by 10 mmHg
increments
What happens to the Glomerular Filtration
Rate as the blood pressure increases?
It increases!
Why does this occur?
More pressure allows the Glomerulus to push
out more filtrate
Activity 3: Combined Effects on
Glomerular Filtration
Procedure: Record a baseline run and compare it
to a run with the Outflow Valve Closed
What was the difference between the two runs?
When the Valve was Closed, there was no Glomerular
Filtration Rate and no Urine Production
What would happen if the all the collecting ducts
in the kidney were blocked?
Pressure would build up
Ducts would burst/break
Would kidney function as a whole be affected if
one nephron was blocked?
No, because the kidney has about one million other
nephrons
Activity 3 continued
How could the body increase
Glomerular Filtration Rate in the kidney?
Dilate the Afferent Arteriole
Constrict the Efferent Arteriole
Increase Blood Pressure supplying the
Glomerulus
_________
Review of the Relationships
within the Renal System
Blood Flow, Glomerular Pressure, Glomerular
Filtration Rate, and Urine Production are related
Constricting the Afferent Arteriole causes …
Decrease in Glomerular Pressure
Decrease in Glomerular Filtration Rate
Decrease in Urine Production
Constricting the Efferent Arteriole causes…
Increase in Glomerular Pressure
Increase in Glomerular Filtration Rate
Increase in Urine Production
Stimulating Urine Formation
Effere
nt
Afferent
Glomerulu
s
Glomerular capsule
PCT
Loop of
Henle
DCT
Collectin
g Duct
Activity 4: Role of the Solute
Gradient on Maximum Urine
Concentration
In urine formation, solutes and water move
from the lumen to the interstitial spaces
Total solute gradient will effect the
movement of solute and water to these
interstitial spaces
Antidiuretic Hormone (ADH)
Increases water permeability in DCT and Collecting Duct
Water flows from high solute conc. into the interstitial
spaces
Water is absorbed
Activity 4 continued
Procedure: Increase the Max. Total Solute
Concentration of the Gradient by 300
milliosmole increments, adding ADH as
well
What happens to the Urine Concentration
as Total Solute Concentration Gradient
(Conc. Grad) increases?
It increases because ADH causes water to
move out of urine and the more solute there is
the more concentrated the urine
Activity 5: Effect of Glucose
Carrier Proteins on Glucose
Reabsorption
There is a limit to the amount of
glucose reabsorbed because carrier
proteins are needed to move them to
the interstitial fluid
If glucose carriers are being used,
excess glucose is eliminated in urine
Procedure: Increase the glucose carriers
by increments of 100
Activity 5 continued
What happened to the glucose concentration in urine
as the number of glucose carriers increased?
Glucose concentration in the urine decreased because
the carriers were able to get the glucose across
If there was more glucose than could be transported
by the available number of glucose carrier proteins,
what would happen to the urine?
An increased glucose concentration in the urine
Why do we expect to find glucose in the urine of a
diabetic person?
The lack of insulin causes a high glucose concentration
The glucose can’t all be absorbed because there are
only so many glucose carriers
Activity 6: Effect of Hormones on
Urine Formation
Excess water = dilute urine
Dehydration = concentrated urine
Hormones control urine concentration
ADH – Produced by Hypothalamus and
Stored in Posterior Pituitary Gland
Increases water permeability
Works at DCT and Collecting Duct
Aldosterone – Produced by Adrenal Gland
Reabsorbs sodium ions and water but loses
potassium ions
Works at the DCT
Activity 6 Continued
Procedure: Compare a baseline run with one when
Aldosterone is added and one when ADH is added
How are the results different when Aldosterone is
added?
Urine Volume decreases
Sodium and Water are retained
Potassium Conc. increases because it is kicked out
How are the results different when ADH is added?
Urine Concentration increases
Urine Volume decreases
Are the effects of Aldosterone and ADH similar or
antagonistic?
Similar (Agonists) - both conserve Sodium and Water
_________
_________
________
_________
_________