Overview and RBF Flashcards
What percentage of people 20 yrs or older have chronic kidney disease?
10%
What percentage of nephrons are cortical vs. juxtamedullary?
85% vs 15%
Which nephrons have long Loops of Henle?
Juxtamedullary
The ascending loop of the kidney and the collecting duct are permeable/impermeable?
highly impermeable
Resistance to RBF from glomerulus to collecting duct
glomerulus proximal tubule thin descending limb thin ascending limb thick ascending limb macula densa distal tubule collecting duct
These determine the relative ability of water and particles to move via a paracellular route
tight junction proteins
______ greatly increases water permeability in the collecting duct by recruiting water channels (aquaporins)
ADH
Subset of peritubular capillaries supplying the JM nephrons
Vasa recta
These cells lie next to the distal tubule and give feedback to the glomerulus and the affarent arteriole concerning the level of flow
macula densa cells
A mechanism that serves to maintain a relatively constant GFR by sensing NaCl levels in the distal nephron and releasing substances that feed back onto the glomerulus to modify arteriolar resistance in both efferent and afferent vessels.
Tubuloglomerular feedback
If the efferent arteriole contracts, what will happen to the filtration fraction?
It will increase
If the efferent arteriole dilates, what will happen to the filtration fraction?
It will decrease
What are the two components of the filtration fraction?
GFR (glomerular filtration rate) and renal plasma flow
The intrinsic ability of the kidney to adjust vascular resistance to maintain blood flow at a relatively constant level when perfusion pressure changes.
Autoregulation
Two mechanisms underlying autoregulation of RBF
- myogenic response
2. tubuloglomerular feedback
Autoregulation of blood flow to the kidneys relies primarily on
the afferent arteriole
Other factors modifying RBF
- nerves
2. hormones (RAAS)
Factors regulating renin release
- decreased stretch in afferent arteriole
- decreased macula densa NaCl delivery
- increased sympathetic nerve activity
When renal blood flow increases, oxygen consumption _____________.
increases
What determines the relative ability of water and particles to move between cells (paracellular).
Two examples of tight junction proteins.
Tight junction proteins
Claudins and occludins
How does ADH greatly increase water permeability in the collecting duct?
It recruits aquaporins.
What are two effects caused by decreased NaCl sensed by the macula densa?
- decrease afferent arteriolar resistance to increase flow
2. increase efferent arteriolar resistance to increase flow
Main action in myogenic response to increased perfusion pressure
Increase resistance at afferent arteriole
Does water reabsorption occur at the glomerulus?
No!
Is water absorption paracellular in the proximal tubule?
Yes
Is water reabsorption paracellular in the collecting duct?
No
Compare the starling forces in the glomerular capillaries to the forces in the skeletal muscle capillaries.
In glomerular capillaries, the hydrostatic pressure of the capillary is higher.
The osmotic pressure of the capillary rises to a greater degree.
Efferent arterioles provide greater resistance than the venules in skeletal muscle.
4 things that increase K+ secretion
- aldosterone
- hyperkalemia
- furosemide
- thiazide diuretics
