Physiology Lo: Glomerular Filtration And Regulation & Measurement Of Rate Of Glomerular Filtration

Front 1

Glomerular ultrafiltration process

Back 1

Plasma moves across porous glomerular membrane under the influence of net filtration pressure

Front 2

What is the first and rate-limiting step in urine production?

Back 2

Glomerular ultrafiltration process

Front 3

Glomerular is similar to __ but contains virtually no __. This is known as __.

Back 3

plasma; protein; plasma ultrafiltrate

Front 4

The glomerular membrane is highly permeable to ___ but impermeable to ___.

Back 4

water and small molecules; proteins/large negative molecules

Front 5

Why is the glomerular membrane highly permeable to water?

Back 5

1. large capillary surface area for filtration
2. large numbers of large pores (fenestrae of endothelium, mesh-like basement membrane)
3. large number of filtration slits

Front 6

What does a high filtration coefficient (Kf) correspond to?

Back 6

high permeability

Front 7

All three layers of glomerular membrane are covered with ___ surface that repels negatively charged proteins such as albumin

Back 7

negatively charged

Front 8

What is the glomerular filtration barrier composed of?

Back 8

endothelium, basement membrane, podocyte epithelium

Front 9

What is found between podocytes that prevent filtration of large molecules?

Back 9

Slit diaphragms

Front 10

What are the 3 sieves in series?

Back 10

1. capillary endothelium
2. basement membrane
3. Bowman's capsule epithelium (podocytes)

Front 11

Starling hypothesis for transcapillary exchange

Back 11

Predicts whether the net movement of fluid and substances will be out of the capillary (filtration) or into the capillary (absorption)

Front 12

For glomerular capillaries, the interstitial osmotic pressure is __ because there is virtually no protein in the filtrate.

Back 12

zero

Front 13

Forces involved in glomerular filtration

Back 13

-[forces favoring filtration] - [forces opposing filtration]
-[glomerular capillary pressure] - [pressure in Bowman's capsule + plasma protein osmotic force]

Front 14

What is the net ultrafiltration pressure?

Back 14

16mmHg

Front 15

What is the magnitude of glomerular filtration rate?

Back 15

125mL/min

Front 16

__ of the glomerular barrier (normal thickness of basement membrane, intact foot processes, presence of negative charges) is critical for normal filtration

Back 16

integrity

Front 17

Glomerular filtration rate equation

Back 17

GFR = Kf [(Pc - Pt) - πp]
= Filtration coefficient x Net filtration pressure

Front 18

Glomerular Filtration Rate (GFR)

Back 18

the amount of plasma filtered between the two kidneys per unit time
-one-fifth (20%) of RPF is filtered at the glomerulus at any one time.

Front 19

Renal Blood Flow (RBF)

Back 19

1200mL/min (20-25% of CO)

Front 20

Renal Plasma Flow (RPF)

Back 20

650mL/min (55% of RBF)

Front 21

Both renal blood flow and glomerular filtration rate are well-autoregulated between mean arterial pressure of __ (flow autoregulation).

Back 21

80 and 180mmHg

Front 22

The intrinsic mechanism (renal auto-regulation) keeps GFR and RBF constant despite changes in ___.

Back 22

renal arterial pressure

Front 23

Changes in renal arterial pressure are caused by..

Back 23

changes in afferent arteriolar resistance

Front 24

Renal auto-regulation allows the kidney to..

Back 24

perform its homeostatic function relatively independently

Front 25

Extrinsic regulation of GFR

Back 25

-Neurohumoral actions (sympathetic nerve activity, catecholamines, angiotensins, prostaglandins, kinins)
-composition of blood (drugs) on renal structures result in changes in GFR and allow the kidney to adjust its function appropriately in response to perturbations

Front 26

Changes in contractility affect what 3 things?

Back 26

filtration area and Kf thus GFR

Front 27

Extrinsic regulators of GFR are mostly agents that affect contractility of __.

Back 27

blood vessels

Front 28

Dopamine is a strong __.

Back 28

vasodilator

Front 29

Mesangial cell

Back 29

specialized connective tissue cells providing support for capillary loops

Front 30

__ affect mesangial cells contractility through specific messenger systems.

Back 30

hormones
-angiotensinII, endothelin, prostaglandins, nitric oxide,
bradykinin

Front 31

Renal auto-regulation

Back 31

minimizes the impact of changes in arterial blood pressure on renal function

Front 32

Renal clearance

Back 32

volume of plasma from which that substance is completely cleared by the kidney (via filtration, reabsorption, secretion) per unit time.

Front 33

The magnitude of the renal clearance of a conserved substance will be __.

Back 33

small

Front 34

Renal clearance formula

Back 34

Cx = (Ux V)/Px

Cx = renal clearance of X
Ux = concentration of X in urine
V = rate of urine flow
Px = concentration of X in blood plasma

Front 35

Inulin can't be __ so it is completely __ and excreted in the urine.

Back 35

reabsorbed/metabolized; filtered

Front 36

If a substance is only filtered at the glomerulus then the amount filtered equals the __.

Back 36

amount excreted

Front 37

The renal clearance of inulin is a measure of __.

Back 37

glomerular filtration rate

Front 38

Clearance of endogenous creatinine is used as an __.

Back 38

estimate of GFR or clearance of inulin

Front 39

Plasma creatinine concentration is used as an ___.

Back 39

indicator of GFR

Front 40

Plasma creatinine concentration is __ correlated with GFR.

Back 40

inversely

Front 41

Under normal steady state, plasma creatinine concentration is kept relatively constant because muscular creatinine production equals renal
creatinine excretion. If the kidney function fails and creatinine excretion decreases, plasma creatinine concentration will be __.

Back 41

elevated