Download P215 Spring 2017: Renal Physiology

P215 Spring 2017: Renal Physiology
Chapter 18: pp. 504-520, 525-527
Chapter 19: pp. 532-548, 553-560
I. Main Components of the Renal System
1. kidneys
2. ureters
3. urinary bladder
4. urethra
4 Major Functions
1.
2.
3.
4.
II. KIDNEY
Basic structure
1. Renal cortex
2. Renal medulla
3. Minor Calyx
Major Calyx
Renal Pelvis
4. Ureter
III. Nephron Anatomy
The nephron is the basic functional unit of the kidney.
There are about 1 million nephrons per kidney.
Major Structures:
A. Afferent arteriole
B. Glomerulus
C. Glomerular Capsule
D. Efferent arteriole
III. Nephron Anatomy (cont.)
Major Structures: (cont.)
E. Nephron Tubules
5 major sections of the nephron tubule:
1. Proximal Convoluted Tubule (PCT)
2. Descending Limb of the Loop of Henle
3. Ascending Limb of the Loop of Henle
4. Distal Convoluted Tubule (DCT)
5. Collecting Duct
III. Nephron Anatomy (cont.)
Major Structures: (cont.)
F. Peritubular Capillaries
Put it all together, and it looks like this:
IV. Nephron Function
Three main processes:
a) filtration, b) reabsorption, c) secretion
A. Filtration =
mechanism:
result:
IV. Nephron Function (cont.)
A. Filtration (cont.)
Glomerular filtration rate (GFR) = total volume of fluid filtered from the plasma per minute.
About _____% of the plasma that enters the glomerulus is filtered into the nephron tubules.
On average, _________ of filtrate are produced per minute, or ____________________ per day!
Autoregulation of GFR:
Goal:
Why?
What would happen to GFR if arterial blood pressure rises and no corrections are made?
How will GFR be controlled intrinsically (i.e. autoregulated) if blood pressure rises?
IV. Nephron Function (cont.)
B. Reabsorption =
mechanism:
result:
C. Secretion =
mechanism:
result:
The Big Picture of Nephron Function
In the end, MANY things will be filtered just because they’re small.
MANY things that were filtered will need to be reabsorbed because we need them.
Additionally, some things that weren’t initially filtered (or too much was reabsorbed) will be
secreted into the nephron for various reasons.
V. REGULATION OF SOME EXTRACELLULAR FLUID COMPONENTS
1) REGULATION OF GLUCOSE.
Filtration:
Reabsorption:
where?
how?
why?
Secretion:
Final net result:
Question? Why is the condition glycosuria (glucose in urine) observed in untreated diabetes
mellitus?
V. REGULATION OF SOME EXTRACELLULAR FLUID COMPONENTS (cont.)
Clinical Application: Potassium
Potassium is found in highest concentration in _________________________ fluid.
What role does potassium play in the body?
What would happen if high [K+] was found in ____________________________ fluid?
2) REGULATION OF POTASSIUM (K+)
Filtration:
Reabsorption:
where?
how?
why?
Secretion:
Final net result:
V. REGULATION OF SOME EXTRACELLULAR FLUID COMPONENTS (cont.)
3) REGULATION OF SODIUM (Na+) AND WATER (H2O)
a) filtration in glomerular capsule (GC)
b) reabsorption in the proximal convoluted tubule (PCT)
how?
net result:
Important question:
If water is allowed to freely follow sodium, then what is happening to the osmotic
gradient between the tubular fluid and the blood plasma?
c) reabsorption in the loop of Henle
NET RESULT through the Loop of Henle =
V. REGULATION OF SOME EXTRACELLULAR FLUID COMPONENTS (cont.)
3) REGULATION OF SODIUM (Na+) AND WATER (H2O) (cont.)
d) reabsorption in the distal convoluted tubule
Effect of Dietary Sodium on reabsorption
NET RESULT after DCT =
e) reabsorption in the collecting duct
Without ADH
FINAL RESULT after CD =
WITH ADH
VI. ACID-BASE BALANCE
Role of the Distal Convoluted Tubule
Metabolic Disorders
Metabolic Acidosis =
potential causes:
Metabolic Alkalosis =
potential causes:
VII. EFFECT OF HORMONES
Hormones play an important role in the regulation of ______________________________ by
monitoring three major fluid characteristics:
a.
b.
c.
VII. EFFECT OF HORMONES (cont.)
Two main hormones are going to do the job of maintaining these three characteristics
within normal levels:
1. Antidiuretic Hormone (ADH) (a.k.a. vasopressin or VPN)
Released when ________________________ is low and _____________________________ is high.
Mechanism:
Effect:
Clinical Questions:
In diabetes insipidus, ADH is either not produced or ineffective. What are the symptoms and
treatments?
In the Syndrome of Inappropriate ADH (SIADH), too much ADH is produced. What are the
symptoms and treatments?
VII. EFFECT OF HORMONES (cont.)
2. Aldosterone
Indirectly released when _________________________________ is low.
Anatomy:
juxtaglomerular apparatus (JGA)
macula densa
granular cells
Mechanism of aldosterone secretion:
1.
2.
3.
4.
5.
Effect of aldosterone secretion:
VIII. Urine Transport and Release
1. ureters
a. conduct urine from kidneys to bladder
b. utilize peristaltic contractions
2. bladder
a. storage of urine
b. distensible organ with smooth muscle walls
3. urethra
a. conveys urine to outside
4. sphincters
- contraction prevents urine flow; relaxation allows urine flow
a. internal: smooth muscle sphincter
b. external: skeletal muscle sphincter
5. micturition (urination)
a. distension of bladder with urine (400-500ml)
b. stimulates bladder stretch receptors
c. sensory input to spinal cord
d. autonomic motor control:
reflex contraction of bladder smooth muscle
relaxation of internal sphincter
e. voluntary relaxation of external sphincter
f. urine flows and contents of bladder lost from body
PRACTICE WORKSHEET FOR GLUCOSE, POTASSIUM, SODIUM, WATER & pH REGULATION