BMS 108 Ch. 17 Renal I

Question 0

What are the four things kidneys regulate?

Answer 0

1. Volume of plasma&raquo_space; BP
2. Waste product removal from plasma
3. Concentration of electrolytes
4. Plasma pH

Question 1

What is the function of the kidneys?

Answer 1

to regulate plasma and interstitial fluid by formation of urine

Question 2

What are the gross anatomy parts of the kidney?

Answer 2

Cortex
Medulla
Renal Pyramids
Renal Columns
Minor Calyces
Major Calyx

Question 3

What is a nephron?

Answer 3

The functional unit of a kidney, responsible for forming urine.

Question 4

How many nephrons per kidney?

Answer 4

more than 1 million

Question 5

What does a nephron consist of?

Answer 5

small tubules and associated capillaries

Question 6

List the specific parts of the nephron tubules.

Answer 6

Glomerular capsule
Proximal convoluted tubule
Descending and Ascending limbs of the Loop of Henle
Distal convoluted tubule
Collecting duct

Question 7

List the renal blood vessels of the nephron.

Answer 7

renal artery
afferent arteriole
glomerulus
efferent arteriole
peritubular capillaries
vasa recta

Question 8

What is the capsule that surrounds the glomerulus called?

Answer 8

Glomerular capsule or Bowman’s capsule

Question 9

What is the structure formed by both the glomerulus and Bowman’s capsule called?

Answer 9

the renal capsule

Question 10

Where does filtrate captured by the renal capsule go?

Answer 10

proximal convoluted tubule

Question 11

What is the function of the nephron?

Answer 11

to filter, reabsorb and secrete

Question 12

Describe the basic pathway that forms urine in the nephron.

Answer 12

Filtration in the renal corpuscle
Reabsorption in the PCT, Loop of Henle
Secretion in the DCT
Urine formed after Collecting Duct

Question 13

What are the three layers that glomerular filtrate must pass through?

Answer 13

1. Glomerular capillaries
2. Basement membrane
3. Slit diaphragms of podocytes

Question 14

Glomerular capillaries are __________ – have large pores between its endothelial cells.

Answer 14

fenestrated

Question 15

What is in the initial filtrate? What doesn’t get through?

Answer 15

H2O and everything dissolved (electrolytes, waste products, hormones, glucose and amino acids); proteins

Question 16

A small percentage of proteins (albumin) gets into the filtrate, how is this reabsorbed?

Answer 16

receptor-mediated endocytosis in the PCT

Question 17

What is Glomerular Filtration Rate (GFR)?

Answer 17

The volume of filtrate produced by both kidneys per minute. Average about 125ml/min in men; totals about 180L/day (45 gallons)

Question 18

What mechanism regulates GFR?

Answer 18

Controlled by extrinsic (sympathetic NS) and intrinsic (renal autoregulation) mechanisms. Vasoconstriction or dilation of afferent arterioles affects rate of blood flow to glomeruli and thus GFR.

Question 19

What is renal autoregulation (intrinsic)?

Answer 19

the ability of the kidneys to maintain relatively constant GFR in the face of fluctuating BP.

Question 20

What two mechanisms are responsible for renal autoregulation?

Answer 20

myogenic constriction and tubuloglomerular feedback

Question 21

What is myogenic constriction?

Answer 21

constriction of afferent arteriole due to smooth muscle responding to an increase in arterial pressure.

Question 22

What is tubuloglomerular feedback?

Answer 22

achieved via effects of paracrine regulators on afferent arterioles that tell the arterioles to constrict.

Question 23

What kind of feedback is tubuloglomerular feedback?

Answer 23

negative feedback

Question 24

How does tubuloglomerular feedback work?

Answer 24

Increased flow of filtrate sensed by macula densa (part of the juxtaglomerular apparatus) in think ascending Loop of Henle >> signals the afferent arterioles to contrict.

Question 25

Sympathetic (extrinsic) activity ________ the afferent arteriole.

Answer 25

constricts

Question 26

How does sympathetic activity in the kidneys help regulate BP?

Answer 26

(via blood volume) by decreasing GFR, thus decreasing urine production with increases blood volume.

Question 27

What are the walls of the PCT constructed of?

Answer 27

single layer of cuboidal cells with millions of microvilli

Question 28

How does the PCT facillitate reabsorption?

Answer 28

During reabsorption, salt, water, and other molecules needed by the body are transported from the lumen through the tubular cells and into surrounding peritubular capillaries.

Question 29

Water is never ________. ___________ are transporter and ________ follows by osmosis.

Answer 29

transported; other molecules; water

Question 30

What is the significance of PCT reabsorption?

Answer 30

- about 65% Na+, Cl- and H2O is reabsorbed in PCT and returned to the bloodstream. Glucose and a.a. also reabsorbed here. - And additional 20% is reabsorbed in descending Loop of Henle - Thus 85% of filtered H2O and salt are reabsorbed early in the tubule

Question 31

Filtered flucose and amino acids are normally _______% reabsorbed from filtrate.

Answer 31

100%

Question 32

How are glucose and amino acids reabsorbed by the PCT?

Answer 32

via carrier mediated cotransport with Na+

Question 33

Describe the mechanism of reabsorption in the PCT.

Answer 33

1. There is coupled transport of glucose and Na+ into the cytoplasm 2. Primary active transport of Na+ across basolateral membrane by Na+/K+ pump 3. Glucose then transported out of the cell via facilitated diffusion and is reabsorbed into the blood

Question 34

Actions in the Loop of Henle depends on ________________.

Answer 34

concentration gradients in the kidney's medulla

Question 35

In order for H2O to be reabsorbed, interstitial fluid must be __________.

Answer 35

hypertonic

Question 36

What is the osmolality of the medulla? cortex? What is this concentration gradient the result of?

Answer 36

1200 -1400mOsm; 300mOsm; from the relationship between the Loop of Henle and vasa recta

Question 37

What is the Countercurrent Multiplier System?

Answer 37

Countercurrent flow and proximity allows the descending and ascending limbs of the Loop of Henle to interact in way that causes osmolality to build in the medulla.

Question 38

Describe Countercurrent Exchange in the Vasa Recta.

Answer 38

- vasa recta is permeable to salt, H2O (via aquaporins) and urea - recirculates salt, trapping some in the interstitial fluid of the medulla - reabsorbs H2O coming out of the descending limb (due to oncotic pressure) - Ascending section has fenestrated capillaries that draw in H2O secreted by the descending limb.