Title: Brief overview of mammalian renal physiology
1Brief overview of mammalian renal physiology
- Jason Williams
- University of Nevada Las Vegas
- 2-28-07
2(No Transcript)
3Outline for renal physiology lecture
- I. Specific functions of the kidney
- II. Kidney structure
- III. Nephron the functional unit of the kidney
- IV. Basic renal process
- V. Specific renal process
- VI. How does the kidney create hyperosmotic
urine? - VII. Renal regulation of sodium, water, and
potassium - VIII. Hydrogen ion regulation
- IX. Diuretics and kidney disease
4- What does the kidney do?
- Kidneys filter plasma to regulate the makeup of
the interstitial fluid and blood.
5What is interstitial fluid?
6Where is Interstitial fluid located?
7- I. Specific Functions of the Kidney
- 1. Form urine (95 water, 5 solutes)
- A. Removal of metabolic waste from plasma
- i. urea (protein breakdown)
- ii. uric acid (nucleic acid breakdown)
- - insoluble in blood
- - can precipitate out in blood and cause gout
- iii. creatinine (muscular creatine phosphate
breakdown)
8- B. Removal of foreign compounds
- - drugs, food additives, pesticides
9- C. maintain water, inorganic ion concentrations
- i. important for proper fluid volume
102. Other Functions of the kidney
- A. Acts as endocrine gland
- i. erythropoietin
- ii. Renin
- iii. 1,25 dihydroxyvitamin D3
- B. Gluconeogenesis during times of fasting
- i. amino acids ? glucose
11- II. Structure of the Kidney
- 1. Location
- - retroperitoneal
- - superior lumbar region
- - twelfth thoracic to the third
- lumbar vertebrae
12- 2. Part of the urinary system
- - ureters
- - bladder
- - urethra
133. External anatomy of the kidney
- - Bean shaped
- - vertical cleft called the renal hilus
-
- - Ureters, renal blood vessels, lymphatics,
- and nerves enter and exit at the hilus
14- 4. Internal anatomy of a kidney
- The kidney has three main regions
-
- A. Renal Cortex
- - outer region (granular)
- B. Renal Medulla
- - inner region (striated)
- - consists of a number of
- triangular structures called
- renal pyramids
- C. Renal pelvis
- - major calyces
15- III. Nephron The functional unit of the kidney
- i. smallest unit capable of forming urine
- ii. microscopic, each kidney has about 1 million
16- 1. The nephron consists of two distinct regions
-
- A. Renal corpuscle
- B. Tubule
17A. Anatomy of the renal corpuscle
- i. Glomerulus
- - Afferent and efferent arterioles
- ii. Bowmans capsule
- - Bowmans space
18B. Anatomy of the tubule
- i. Very narrow hollow tube of single celled
epithelial tissue. - ii. Contiguous with
- Bowmans capsule
19C. Tubule consists of
- 1. Proximal tubule (convoluted and straight)
- 2. Loop of Henle (descending and ascending)
- 3. Distal convoluted tubule
- 4. Connecting tubule
- 5. Collecting duct
20D. Vascularization of the nephron
- Two sets of capillaries
- a. Glomerulus
- b. Peritubular capillaries
- Connected by efferent
- arteriole
21IV. Basic renal process
- 1. Urine formation
- A. begins with glomerular filtration ends with
urine formation. -
22- B. glomerular filtrate has essentially the same
concentrations of solutes as blood plasma, minus
proteins
23B. Glomerular filtrate ? Urine
Substance Amount Filtered per day Amount excreted per day
Water, L 180 1.8
Sodium, g 630 3.2
Glucose, g 180 0
Urea, g 54 30
24C. How is glomerular filtrate altered as it moves
through the tubule?
- -Tubular reabsorption
- -Tubular secretion
- Excreted filtered - reabsorbed secreted
25B. Glomerular filtrate ? Urine
Substance Amount Filtered per day Amount excreted per day
Water, L 180 1.8
Urea, g 54 30
Penicillin 3 10
Creatinine, g 20 20
26V. Closer look at renal processes
- 1. glomerular filtration
- - glomerular filtrate has essentially the same
concentrations of solutes as blood plasma,
minus proteins
27A. Glomerular filtrate passes through three layers
- i. Single-celled capillary endothelium
- ?
- ii. Non-cellular proteinaceous
- layer of basement membrane.
- ?
- iii. Single-celled epithelium
- lining (podocytes)
28B. Forces involved in filtration
- Net glomerular filtration
- pressure
- PGC-PBS-pGC
- 55 - 15 - 30 10mmHG
29C. Glomerular Filtration Rate (GFR)
- GFR the volume of fluid/plasma filtered from
the glomeruli to the Bowmans space per unit
time. - GFR 180 L/day for average adult
- blood volume filtered 60 times per
day - GFR is under physiological regulation
302. Clinical determination of GFR
31- A. Introduction
- i. Estimated glomerular filtration rate by
measuring inulin and creatinine clearance. - ii. Why? Abnormal GFR may suggest renal disease
(the leading cause of death in captive cheetahs)
32- B. Brief Materials and Methods
- i. measure of GFR
- 1. injected cats with known amount of inulin
-
-
- Inulin
- - foreign polysaccharide
- - fully filtered
- - not reabsorbed
33B. Brief Materials and Methods (Cont.)
- 2. Determine amount of inulin in serum and urine
sample - 3. Calculate GFR in milliliters
- (Urine conc. of inulin) X (urine volume)
(serum conc. of inulin) - 4. Report final GFR as ml min-1 kg-1
34C. Results
Ccr creatinine clearance rate - Creatinine
produced endogenously - typically only
filtered - measured in same fashion as inulin
GFR
35D. Conclusions
36Tubular Reabsorption
373. Reabsorption
- A. Occurs in proximal tubule and loop of Henle
38- B. General process
- i. Luminal membrane ? basolateral membrane ?
interstitial fluid ? peritubular capillary
ii. Tight junction ? interstitial fluid ?
peritubular capillary
39- C. Tubular reabsorption occurs by
- i. Diffusion
- water, urea, other lipid soluble substances
- ii. Mediated transport
- Move substances uphill against diffusion
gradient. (glucose, amino acids, etc.)
40(No Transcript)
41D. Efficiency of tubular reabsorption
Substance Amount Filtered per day Amount excreted per day Percent reabsorbed
Water, L 180 1.8 99.0
Sodium, g 630 3.2 99.5
Glucose, g 180 0 100
Urea, g 54 30 44
Rates of reabsorption are under physiological
control
42Tubular Secretion
434. Tubular Secretion
- A. Moves substances from
- - peritubular capillary ? tubular lumen
- B. occurs by diffusion or mediated transport
- C. secreted substances
- hydrogen ions, potassium, foreign chemicals,
choline etc.
445. Division of Labor in Nephron
- A. Renal corpuscle filtrate
- B. Proximal tubule primary reabsorption
- C. Proximal tubule primary secretion
45- D. Renal D. Loop of Henle reabsorption
- E. Distal segments fine tuning, under
homeostatic control