Glomerular Filtration

Question 1

Glomerular Filtration

Answer 1

Filtration of blood at kidney’s nephron (movement from blood to tubular system). Step in producing urine

Question 2

Peritubular Capillaries Secretion

Answer 2

Substances added directly from blood (peritubular capillaries) to urine (forming in renal tubule)

Question 3

Where does blood enter nephron

Answer 3

Afferent arteriole to Boweman’s (glomelular) capsule via diffusion

Question 4

What substance shouldn’t enter Boweman’s capsule

Answer 4

Large proteins. If protein is found in urine it indicates problems with glomerulus

Question 5

Glomerulus Def

Answer 5

Dense capillary network in Boweman’s capsule. Plasma filters through this

Question 6

Glomerulus (boweman’s) capsule

Answer 6

Collects glomuler filtrate (plasma only). Blood cells and protein don’t pass through this but move with other unfiltered plasma (80%) into efferent arteriole (smaller then afferent)

Question 7

3 layers of globular filtration

Answer 7

capillaries, filtration membrane and Boweman’s capsule

Question 8

Make up of capillary endothelium

Answer 8

Simple fenesetrated

Question 9

Glomerular Capsule Make up

Answer 9

Basement membrane (negatively charged, lipid membrane (repels proteins)), podocytes (structures that filter by size, stops large molecules entering) and filtration slips (gaps betwwen podocytes)

Question 10

Filtration Forces

Answer 10

Glomerular Capillary Blood Pressure (favours), plasma-colloid osmatic pressure (opposes) and boweman capsule hydrostatic pressure (opposes)

Question 11

Greatest force in filtration

Answer 11

Glomerular capillary blood pressure. Significantly higher, results in net filtration pressure being positive (in favour, filtration occurs). Caused by afferent arterioles having a much larger lumen then efferent causing a build up of plasma

Question 12

Osmotic Gradient Caused by

Answer 12

Large proteins in plasma forms osmatic gradient across membrane. Holds plasma in place

Question 13

Hydrostatic Pressure Caused By

Answer 13

Filtrate already in capsule works against filtration

Question 14

Glomerular Filtration Rate

Answer 14

ml of plasma filtered in both kidneys per minute. Clinically used to asses kidney function. When kidney’s aren’t working glomerular filtration rate decreases. Creatine levels in blood increases as GFR decreases

Question 15

Tubular system function

Answer 15

Reabsorbs filtered plasma. Highly selective reabsorption (removes substances). Most is reabsorbed but some passes into urine. Exchange of substances caused by peritubular capillaries

Question 16

Descending Limb of loop of Henlee

Answer 16

reabsorbed to blood: H20 excreted from blood: urea

Question 17

Ascending Limb of loop of Henlee

Answer 17

Reabsorbs to blood: Na+, Cl- and K+

Question 18

Where does most reabsorption to blood occur

Answer 18

Proximal Convoluted Tubule

Question 19

Factor that effects how much sodium and water is absorbed

Answer 19

Blood Pressure

Question 20

Transepithelial transport

Answer 20

Lumen of tubule, entering membrane of tubular cell, passing through cell’s cytosol, exiting through cell’s basolateral membrane, moves through interstitial fluid, moves throgh capillary cell into it’s lumen

Question 21

Relationship between high blood pressure and Na+ levels

Answer 21

High Na+ levels = high water retention = high blood volume

Question 22

How much energy does sodium reabsorption require in kidney

Answer 22

80% of total kidney energy expenditure. Active transport

Question 23

Where Na pumps are located

Answer 23

Basolateral membrane. Moves ions across conc gradient

Question 24

How does Na+ move into loop of Henlee

Answer 24

Down conc gradient. Passive

Question 25

How does Na+ move into blood vessels

Answer 25

Up conc gradient. Active transport, ATPase pumps

Question 26

Proximal Tubule Na+ absorption

Answer 26

Most (67%). Aids reabsorption of other substances (secondary active transport) eg glucose

Question 27

Loop of Henlee Na+ absorption

Answer 27

25% absorbed. Helps produce urine in altering blood pressure

Question 28

Distal Convoluted Tubule Na+ absorption

Answer 28

8% absorbed. Controlled by aldosterone

Question 29

What hormone controls absorption of water

Answer 29

Anti-diuretic hormone

Question 30

GLUT Transporter

Answer 30

Glucose facilitated diffusion across basolateral membrane

Question 31

Regulation of Glucose Reabsorption

Answer 31

Not controlled by kidney. Controlled by capacity of glucose transporters. All glucose should be reabsorbed into plasma (needed in liver and endocrine). In diabetes glucose won’t be fully reabsorbed

Question 32

Potassium secretion

Answer 32

Active via ATPase pumps. K+ is secreted from blood as Na+ is reabsorbed

Question 33

Urea production

Answer 33

Breakdown of protein in liver. Filtered by kidneys (~50% filtered urea is reabsorbed). Blood urea nitrogen test (BUN) is an indication of kidney health