Urinary System Anatomy & Physiology

Question 1

Kidney plays important role in: (3)

Answer 1

removal of metabolic wastes
regulation of water & electrolytes
maintenance of body’s acid-base equilibrium

Question 2

% of initial ultrafiltrate that is reabsorbed

Answer 2

99%

urine output is only 1% of the filtered plasma volume

Question 3

Principle solutes in urine

Answer 3

urea, Cl-, Na+, K+, phosphate, sulfate creatinine & uric acid

Question 4

urine formation consists of what 2 steps?

Answer 4

1. plasma filtration at glomeruli

2. reabsorption & selective secretion by renal tubules

Question 5

anatomy of glomeruli

Answer 5

located in outer cortex of kidney, exclusive site of plasma filtration

Question 6

5 distinct areas of the nephron: (be able to label picture)

Answer 6

1. glomerulus - capillary tuft surrounded by Bowman’s capsule where filtration occurs
2. Proximal convoluted tubule
3. loop of henle
4. distal convoluted tubule
5. collecting tubule

Question 7

Afferent arteriole

Answer 7

supplies blood individually to the glomerulus of each nephron

Question 8

force behind glomerular filtration

Answer 8

high hydrostatic pressure of afferent arteriole

Question 9

3 structures of glomerular filtration barrier

Answer 9

1. capillary endothelium
2. trilayer basement membrane - often gets damaged by Ab-Ag complexes
3. filtration diaphrams - located between podocytes of Bowman’s space

Question 10

Selectivity of Glomerular filtration

Answer 10

based on molecular size & charge - allows water & small molecules to pass rapidly
endothelium has negative charge that molecules must overcome to pass

Question 11

Podocytes

Answer 11

foot-like structures that surround the glomerulus & share its basement membrane, spaces between them are called ‘filtration slit’s & they regulate what passes through based on size & charge

Question 12

Renin

Answer 12

large amounts of secretory granules containing renin are present in afferent arteriole of juxtaglomerular apparatus
causes angiotensin formation & aldosterone secretion–> retain Na+ & water

Question 13

3 ways renin can be released

Answer 13

1. decreased arterial blood pressure / volume
2. decreased Na+ or increased K+
3. vascular hemorrhage

Question 14

renal system buffer for blood pH regulation

Answer 14

increases or decreases excretion of H+
increases/ decreases formation of ammonia
increases/decreases reabsorption of HCO3-

Question 15

3 mechanisms that maintain blood pH & relies on tubular secretion of H+

Answer 15

1. H+ secreted into PT lumen preventing loss of HCO3-
2. depends on amount of phophate in the ultrafiltrate
3. depends on ammonia secretion & following change of Na+ for ammonium ions

Question 16

end goal of renal blood pH regulation

Answer 16

H+ secretion results in Na+ or HCO3- reabsorption

Question 17

efferent arterioles

Answer 17

blood leading the way from the glomerulus; these give rise to a second capillary bed ‘ peritubular cappilaries’ that surround the tubules in the corticical region

Question 18

vasa recta

Answer 18

surrounds the loop of henle in the renal medulla

Question 19

Juxtaglomerular Apparatus

Answer 19

controls blood pressure & the rate of filtration

tubular & vascular cells in this area are specialized

Question 20

macula densa

Answer 20

distal tubular cells from the juxtaglomerular apparatus that governs the filtration rate

Question 21

Vasopressin

Answer 21

controls water reabsorption in collecting tubules

causes a change in the tubule epithelium