EXAM: Structure/ Function

Question 1

What is the function of the kidneys

Answer 1

• contribute to the acid balance by removing H+ and bicarbonate (HCO3-)
• produce glucose by glucoeogenesis
• produce erythropoietin to stimulate the formulation of erythrocytes
• Produce calcitriol = active form of vitamin D
• produce renin
• Selective excretion: importin products retained (glucose, AA, proteins), waste removed

Question 2

What is the function of the urinary system

Answer 2

• the primary regulator of fluid volume and ion concentration

Question 3

What is renin

Answer 3

• an enzyme that regulates the formation of angiotensin II (regulates blood pressure and aldosterone)

Question 4

What must remain constant in the urinary system

Answer 4

• composition and volume of body fluids
• stabilize osmolairy
• secrete excess/ retain (reabsorb) when source is scarce

Question 5

What is considered waste to the kidneys

Answer 5

• foreign substance
• body organic wastes: urea (metabolism of proteins), bile, degradation of hemoglobin

Question 6

Where are kidneys located

Answer 6

• upper abdominal wall

Question 7

What is the structure of the kidneys

Answer 7

• Arteries, veins and urters enter through the renal hilus
• composed of an outer cortex and inner medulla
• basic urine forming units = nephrons

Question 8

What is the structure of the nephron and function

Answer 8

composed of two main parts

1. Glomerulus: filters blood
2. Tubular system: composed of several sections- reasrobtion of filtered substances, secretion of others

Question 9

What is the blood supply composed of in the nephron

Answer 9

• glomerular capilleries
• peritubular capillaries
• vasa recta (capillaries of the medulla)

Question 10

Where is the glomerulus found

Answer 10

• confined in the cortex
• enclosed in the Bowmans capsule

Question 11

What does the glomerulus do

Answer 11

• protein free fluid is filtered and accumulate in the Bowmans space and then enters the first part of the tubule which is the proximal tubules

Question 12

What is the glomerus composed of

Answer 12

• many parallel capillaries
• blood enter through afferent arteriole
• capillaries do not connect the venues but connect with effecter arteriole that will feed the peritubular capillaries

Question 13

What its the tubular system made of

Answer 13

-walls of a single layer of epitheilal cells

Question 14

What are the 4 major components of the tubular system

Answer 14

1. Proximal tubule
2. Loop of henle
3. Distal tubule
4. Collecting ducts

Question 15

What do the collecting ducts do

Answer 15

• receive distal tubules from multiple nephrons, small ducts merge into large ducts and bring urine to the renal penis

Question 16

What does the distal tubule do

Answer 16

• highly convoluted in the cortex

Question 17

What does the loop of henle do

Answer 17

• harpin structure in the medulla and composed of descending thin limb, and thick ascending limb

Question 18

What is the proximal tubule

Answer 18

• highly convoluted in the cortex

Question 19

Where does the initial part of the distal tuble pass

Answer 19

• between the affect and efferent arteriole of its own glomerus using epithelial cells called macula densa

Question 20

What produces and secreate renin

Answer 20

• adjacent smooth muscle cells called juxtaglomerular

Question 21

What are the three basic renal processes

Answer 21

1. glomerular filration
2. Tubular reabsorption
3. Tubular secretion

Question 22

What is glomerular filtration do

Answer 22

• filteration of plasma from glomerular capillaries into Bowmans space
• production of protein free folate of plasma
• glomerulus has a complex network of capillaries and specilzied structure designed to retain cells and medium and high molecular weight proteins

Question 23

What is GFR

Answer 23

• glomerular filtration rate is an important index of renal function

Question 24

What is Tubular reabsorption

Answer 24

• movement of substance from tubular lumen to peritubular capillaries

Question 25

What is Tubular secretion

Answer 25

- movement of substance from peritubular plasma to tubular lumen

Question 26

What does the glomerular membrane consist of

Answer 26

1. Capillary endothelium: fenestrated on about 10% of their surface --> blocks cells, not blood constituents 2. Basal lamina: mesh of proteins blocks most of the plasma proteins 3. Inner epithelial layer of Bowmans capsule: visceral epithelium composed of podocytes -->> last level of filtration between the fingers

Question 27

What is the overall function of the glomerular membrane aka basal lamina

Answer 27

- function collectively as a fine sieve - basal laminate is the best selection unit against proteins - Basal laminate also negatively charged = repulses proteins

Question 28

What is the glomerular filtration rate

Answer 28

- forces across glomerular capillary wall given filtration pressure (same as in capillaries) - differences in hydrostatic and oncotic pressure

Question 29

How is filtration rate reduced in glomerular

Answer 29

- hydrostatic pressure in Bowmans space (normal low) - Plamsa oncotic pressure within glomerular capillary

Question 30

What is glomerular filtration facilitated by?

Answer 30

- higher hydrostatic pressure of blood in capillaries (remains fairly constant along capillary)

Question 31

What is the glomerular filtration similar to

Answer 31

- capillary exchange

Question 32

When is filtration rate higher

Answer 32

- in first part of capillary where the osmotic pressure is lower

Question 33

When does rate of filtration decrease

Answer 33

- further along while the osmotic pressure increases due to the proteins stuck in the blood compartments

Question 34

What are the primary determinants of the GFR (eq)

Answer 34

- GFR= Pf x Kf pf= net filteration pressure (average over entire glomerus) Kf+ ultrafiltration coefficient = product of the filtration barrier permeability and surface area

Question 35

How is the GFR regulated

Answer 35

- kidneys

Question 36

Can hydrostatic pressure in glower space and oncotic pressure be regulated?

Answer 36

- No

Question 37

what does blood flow in the glomerular capillaries (hydrostatic pressure) regulated

Answer 37

- depends on 2 arterioles 1. afferent: enters the glomerulus 2. efferent: exits the glomerulus

Question 38

What does affecting the constriction level of arterioles do

Answer 38

- determine the hydrostatic pressure in the capillaries ( locally)

Question 39

What are the two levels of control that will effect the blood (capillaries) hydrostatic pressure

Answer 39

- renal modulation of systemic blood pressure and blood volume (extrinsic as it affects the entire body) - renin-angiotensin-aldosterone system - intrinsic control of renal blood flow, glomerular capillary pressure and ultra filtration coefficient = auto regulatory mechanisms

Question 40

What is renin-angiotensin-alderstone

Answer 40

- involved in long standing falls in BP or when decreased BP is accompanied by decreased extracellular fluid volume - release of renin from juxta-glomerular cells by: - reduced stretch of renin cells in the renal arterioles (baroreceptors) - sympathetic nerve impulses: arterial baroreceptors respond to fall in BP by "unbraking" sympathetic nerve activity in kidney

Question 41

What is the effect of renin secretion on Angiotensin II in the plamsa

Answer 41

- increse

Question 42

What is angiotensin II

Answer 42

- a potent vasoconstrictor and acts to increase systemic BP and renal perfusion pressure - it stimulates release of aldosterone (adrenal cortex) and vasopressin (pituitary) - augmented fluid uptake increases intravsaular volume and improves renal perfusion to turn off renin release

Question 43

What does vasopressin do

Answer 43

- enhances urea and water reabsorption

Question 44

What dies aldosterone do

Answer 44

- enhance sodium/ water reasorption

Question 45

What is auto regulation (intrinsic)

Answer 45

- is at the level of the kidney - it prevents short term changes in the arterial blood pressure to affect GFR - feedback mechanism that allows the kidney to var5y resistance of the afferent arteries - smooth muscle cells react to increase the stretch by contacting - cells in the macula dense (distal tubule) secrete an undefined factor that stimulates sooth muscle cell contraction

Question 46

What does auto regulation affect

Answer 46

- variation in local arterial blood pressure on: - perfusion of the kidney (renal blood flow) - GFR - urine formation - important because small changes have a great effect on urine volume