Renal Function Flashcards
How does urinary excretion of solutes and water influence the volume and composition of plasma? What other processes affect plasma volume and concentration?
- Increased excretion of water: decreases the volume of plasma, increases solute composition of plasma.
- Increased solute excretion: decreases volume of plasma, decrease in solute concentration.
- Other processes: RAAS, Angiotensin process
Name the functions of the Urinary System.
- regulates plasma ionic composition (Na/K)
- regulates plasma volume (long term BP reg)
- regulate plasma osmolarity
- regulate plasma pH
- remove metabolic waste products and other foreign substances from plasma
- secrete erythropoietin and renin
- activate vitamin D3 to calcitriol
- gluconeogenesis
In glomerular filtration, how does filtrate move?
from glomerulus to Bowman’s capsule
In reabsorption, how does filtrate move?
from tubules to peritubular capillaries
In secretion, how does filtrate move?
from peritubular capillaries to tubules
In excretion, how does filtrate move?
from tubules out of body
How many ml/L of filtrate get filtered in glomerular filtration?
125 mL/min or 180 L/day
There are three layers that filtrate must cross to get to the Bowman’s capsule from the Glomerulus. What are they?
- Fenestrated capillaries
- Glomerular basement membrane
- Visceral layer of the glomerular capsule
Which Starling Forces favor filtration? Choose all that apply: A. Hydrostatic Pressure of GC B. Oncotic Pressure of BC C. Hydrostatic Pressure of BC D. Oncotic Pressure of GC
A. with a value of 60mmHg and B. with a value of 0mmHG
Which Starling Forces oppose filtration? Choose all that apply: A. Hydrostatic Pressure of GC B. Oncotic Pressure of BC C. Hydrostatic Pressure of BC D. Oncotic Pressure of GC
C. with a value of 15mmHg and D. with a value of 29mmHg
What is the formula for finding Glomerular Filtration Pressure (GFP)?
(Pgc+Onc.bc)-(Pbc+Onc.gc)
What is the formula for finding the percentage of plasma filtered out every minute? (Filtration Fraction)
Glomerular Filtration Rate
_____________________
Plasma Flow Rate
True or False: 100% of glucose is filtered out.
True. We will reabsorb all of it. If saturation occurs, the excess with be excreted.
What percentage of filtered fluid is reabsorbed?
99.2%
True or False: A large increase in GFR means a large increase in volume of fluid filtered and excreted.
False. A small increase in GFR means a large increase in volume of fluid filtered and excreted.
In what range is there intrinsic control of GFR?
80-180mmHg. Anything outside that range is controlled extrinsically.
What are the intrinsic regulators of GFR and how do they work?
Myogenic regulation: smooth muscle in the wall of afferent arterioles sense an increase in BP and contract in response to the stretch.
Tubuloglomerular feedback: Macula densa cells secrete paracrine factors in response to an increase flow past them. Smooth muscles contract in response.
Mesangial cell contraction: contract to deep pressure
What controls GFR extrinsically?
Decreases in BP can decrease GFR. This is caused by dehydration, hemorrhage, and the like. It is done to conserve volume.
Extrinsic Control of BP and MAP
Neural and Hormonal controls
Is the control of afferent and efferent arteriolar resistance by renal sympathetic neurons an example of intrinsic or extrinsic control? Why?
Extrinsic, because it originates outside of the nephron
How does an increase in sympathetic activity tend to affect GFR?
An increase in sympathetic activity will decrease GFR.
There are two types of reabsorption. What are they and where do they occur?
- Unregulated: occurs in the PCT
2. Regulated: occurs in DCT and collecting ducts -regulated by hormones.
What are the barriers for reabsorption and secretion?
Epithelial cells of renal tubules and endothelial cells of capillaries (minimal).
True or False: The osmolarity of filtrate in the glomerular capsule is equal to that of blood plasma.
True, they are isoosmotic.
