Renal System

Question 1

functions of renal system

Answer 1

-Filtration and secretion
-Elimination
-Homeostatic regulation of blood plasma

Question 2

filtrate

Answer 2

water, small molecules, ions that can pass through membrane
- pressure diff forces filtrate across filtration membrane

Question 3

renal fraction

Answer 3

The portion of the total cardiac output that flows through the kidneys
- 12-30% (average 21%)

Question 4

glomerular filtration rate

Answer 4

amount of filtrate formed in all the renal corpuscles of both kidneys each minute
180L/day

Question 5

filtration membrane

Answer 5

Keeps proteins and blood cells out of Bowman’s capsule. Mostly ions, water, fluids will enter since the membrane is permeable to smaller molecules.

Question 6

filtration pressure

Answer 6

pressure gradient responsible for filtration; forces fluid from glomerular capillary across membrane into lumen of Bowman’s capsules

Question 7

factors effecting fluid movement

Answer 7

glomerular capillary pressure (GCP)
capsule pressure (CP)
blood colloid osmotic pressure (BCOP)

Question 8

glomerular capillary pressure

Answer 8

blood pressure in glomerular capillary move fluid from blood into bowman’s capsule
(positive pressure system)

Question 9

capsule pressure

Answer 9

pressure from lumen of Bowman’s capsule moves fluid from Bowman’s capsule into glomerular capillary
- push back on fluid trying to enter since there is already some there
- stops filtration

Question 10

blood colloid osmotic pressure

Answer 10

The largest driving force for pulling fluid from the interstitial spaces back into the capillaries due to osmotic pressure of colloids in the blood
- greater at end of glom.caps than beginning
- negative pressure system in urine system

Question 11

Filtration Pressure (FP)

Answer 11

FP = GCP - BCOP - CP
-This is the average pressure acting to force water and dissolved material out of the blood and into the filtrate

Question 12

glomerular nephritis

Answer 12

proteins enter the filtrate and filtrate exerts an osmotic pressure, increasing volume of filtrate

Question 13

high glomerular capillary pressure

Answer 13

is due to:
- low resistance to blood flow in afferent arterioles
- low resistance to blood flow in glomerular capillaries
- high resistance to blood flow in efferent arterioles (smaller diameter)

Question 14

increase filtration

Answer 14

dilate afferent arteriole (enter nephron) and constrict efferent arteriole (leave nephron) = increase GCP = increase FP = increase filtration

Question 15

tubular reabsorption

Answer 15

the movement of substances from the tubular fluid back into the blood
- proximal convoluted tubule (PCT)
- Loops of Henle (ALH and DLH)
- distal convoluted tubule (DCT)
- collecting ducts

due to: diffusion, active transport, facilitated diffusion, cotransport, and osmosis

reabsorbs 99% of filtrate volume

Question 16

reabsorption in proximal tubule

Answer 16

• active transport moves Na from basilar membrane of PCT cell into Interstitial fluid, which makes a concentration gradient out of the cell into IF, which Na follows from the apical membrane out
• thru apical membrane: Na, Cl, glucose, AA, water
• thru basilar membrane (cotransport): Na, K, Cl, glucose, AA, water
  Active:
  Filciated:
  osmosis:

Question 17

Reabsorption in Loop of Henle

Answer 17

• LH descends into medulla; IF is high in solute = water moves out of lumen
• DLH is permeable to water, ALH is to solutes
• solutes leave ALH and enter descending vasa recta (Na by active transport then conc gradient of Na, K, Cl)