Lecture 28- Glomerular Filtration Andtubular Reabsorption

Question 1

Glomerular filtration rate (GFR)

Answer 1

Volume of filtrate formed each min by all glomeruli of kidneys combined

Question 2

Three direct proportional factors of glomerular filtration

Answer 2

1. Net filtration pressure
2. Total surface area available for filtration
3. Filtration membrane permeability

Question 3

Intrinsic controls (renal auto regulation)

Answer 3

Maintains glomerular filtration rate

Myogenic mechanism and tubuloglomerular feedback controls

Question 4

Extrinsic controls (neural and hormonal regulation)

Answer 4

Maintain systemic blood pressure through nervous and endocrine mechanisms

Question 5

What is tubuloglomerular feedback mechanism directed by?

Answer 5

macula dense cells that respond to the filtrate NaCl concentration

Question 6

Extrinsic neural mechanisms

Answer 6

Includes stress induced sympathetic nervous responses

Constricts afferent arterioles and decrease glomerular filtration ate but increase systemic blood pressure and redirects blood flow to other organs

Question 7

Hormonal renin angiotensin aldosterone) mechanism

Answer 7

Uses sequence of hormones, starting with renin from kidneys to constrict arterioles throughout body, increasing blood pressure

Question 8

Tubular reabsorption

Answer 8

Selective trans epithelial process that begins as soon as filtrates enters proximal convoluted tubule

Question 9

Trans cellular route

Answer 9

Solute enter apical membrane, travels through cytosol and exits via basolateral membrane

Solute then enters blood through endothelium of peritubular capillaries

Question 10

Para cellular route

Answer 10

Solutes move between tubule cells, route limited by tight junctions

Water, Ca2+, Mg2+, K+ move via this route

Question 11

Active tubular reabsorption

Answer 11

Requires use of ATP

Question 12

Passive tubular reabsorption

Answer 12

Involves movement of molecules down electrochemical gradients by diffusion, facilitated diffusion or osmosis

Question 13

Primary active transport

Answer 13

when Na+ is actively transported across basolateral membrane and bulk flow of water sweeps it into adjacent peritubular capillary

Question 14

Transport maximums

Answer 14

Exist for most substances reabsorbed via transport protein

Question 15

What tubule is most active in reabsorption?

Answer 15

Proximal convoluted tubule

Nearly all glucose, amino acids and vitamins are absorbed along with 65% of water and Na+

Question 16

Descending and ascending limb permeability

Answer 16

Descending limb- permeable to water

Ascending limb- impermeable to water

Question 17

Tubular secretion

Answer 17

Most active in proximal convoluted tubule, also occurs in collecting ducts and distal convoluted tubules

Functions like reabsorption in reverse, transporting substances into tubular fluid

Removes unwanted solutes from blood that were too big for glomerular filtration