Renal Flashcards
kidneys are retroperitoneal or intraperitoneal?
retroperitoneal (behind peritoneum)
Blood enters each kidney via the ______ artery
renal
What type of vessels are arterioles?
resistance vessels
What type of vessels are capillaries?
exchange vessels
What are the 2 types of nephrons and where are they located?
1) cortical nephrons are in the cortex of the kidney and wrap around
2) juxtamedullary nephrons are besides the medulla and extend into medulla but are not wrapped around (run parallel to loop of henle)
Renal arteries branch off of _______ ______
abdominal aorta
Vasa recta are straight vessels. What type of “exchangers” are they?
osmotic exchangers
What is the main function of kidneys?
filter blood and regulate total body water
What is blood composed of?
mostly water
Water is _______ of body weight
60% (2/3 water in ICF, and 1/3 water in ECF)
What is ECF composed of?
25% plasma and 75% IF
ECF volume is monitored by what?
sensors in the vascular system
Where are the low volume sensors located?
both atria, R ventricle, and large pulmonary vessels
What are low volume sensors measuring?
measuring how much filling pressure there is in both atria, R ventricle and the large pulmonary vessels
What happens if the low volume sensors detect a decrease in filling?
1) sensors activate sympathetic NS
2) vasoconstriction
3) increase BP
4) ADH secretion
5) increase water reabsorption
6) increase volume and pressure
What happens if the low volume sensors detect increased distention due to too much pressure?
1) release ANP and BNP
2) increase excretion of sodium and water at the kidneys
3) volume decreases
Where are the high volume sensors located?
aortic arch, carotid sinus, and the JG apparatus of the kidneys
What happens if the high volume sensors detect a decrease in BP?
1) activate sympathetic NS
2) increase ADH
3) retain water
4) increase BP
5) release renin
What happens if the high volume sensors detect an increase in BP?
1) activate parasympathetic NS
2) suppress renin from being released
When volume sensors detect any change in pressure, what does this trigger? What does this do?
triggers renal system and makes adjustments to the excretion of NaCl and water
When volume sensors detect any change in pressure, what is stimulated first and then second?
first = parasympathetic or sympathetic NS
second= kidneys
What happens if ECF volume expands?
it will excrete sodium and water
What happens if ECF volume contracts?
it will retain sodium and water (decrease excretion)
What happens when a pt is severely dehydrated?
1) decrease in fluid volume
2) decrease BP
3) sympathetic NS is activated
4) vasoconstriction
5) decrease in GFR
6) retain sodium/water
7) volume is conserved
8) renin triggers Ang I
9) triggers Ang II (potent vasoconstrictor)
10) ADH is secreted
11) water reabsorption
12) counteract dehydration
What happens if a pt ingests high levels of salt/sodium?
1) increase water reabsorption (from ICF to ECF, more NaCl is reabsorbed at the PCT and water shifts from ICF to ECF)
2) increase ECF volume
3) ADH released
4) absorb water at renal system
5) counteracts high osmolarity
6) pt will now have high ECF volume
7) kidneys will excrete salt and water
8) osmolarity returns to normal
9) BP returns to normal
What is SIADH?
syndrome of inappropriate ADH
What happens if a pt is secreting excess amounts of ADH in the body?
1) increase retention of water
2) increase BP
3) diluting body fluids
4) hyposmotic
5) urine becomes hypoosmotic
6) water always goes to where it should (2/3 to ICF and 1/3 to ECF, if ADH is uncontrolled then extra water can go to the brain cells and result in a coma)
Define clearance
rate at which substances are removed or cleared from plasma
What is renal clearance?
volume of plasma completely cleared of a substance by kidneys per unit time
renal clearance can be from __________ml/min
0-600ml/min
What is the clearance of albumin?
0
(plasma proteins never leave due to exerting oncotic pressure)
What is the clearance of glucose? Why?
0
100% of glucose is reabsorbed back into the bloodstream
T/F:
It is normal to have glucose in urine
false!
What is the clearance of sodium, phosphate, chloride, and urea?
greater than 0
(kidneys are filtering these ions but only about 50% is getting reabsorbed)
If clearance is less than filtration = __________
reabsorption
Kidneys receive what percentage of total CO?
20-25%
What are the renal blood flow (RBF) functions?
1) bring in nutrients
2) bring products to kidneys for excretion
3) deliver oxygen and remove CO2 from nephron cells
Renal blood flow (RBF) indirectly determines GFR. What does low GFR mean?
low blood flow and less reabsorption
Renal blood flow (RBF) indirectly determines GFR. What does high GFR mean?
high blood flow and more reabsorption
high renal blood flow modifies rate of solute and water reabsorption by PCT
it helps with the conc. and dilution of urine
How does RBF relate to the Q= delta P/R eq?
blood flow =pressure gradient/resistance
delta P in this case is the difference between renal artery and renal vein
To change RBF, you must change ________ _________
arteriolar resistance
What are the major resistance vessels of the kidneys?
afferent arteriole, efferent arteriole, and cortical radiate arteries
Afferent and efferent arterioles have ___ receptors. What stimulates these receptors and which one has more of these receptors?
alpha 1 receptors
sympathetic NS stimulates alpha 1 receptors
afferent arterioles have more alpha 1 receptors
What happens if sympathetic NS stimulates the alpha 1 receptors on afferent arterioles?
1) vasoconstriction
2) increase resistance
3) decrease RBF + GFR
Ang II is a potent vasoconstrictor that is produced systemically but also produced in the _______ locally
kidneys
Ang II _______ both afferent and efferent arterioles
constricts
low levels of Ang II will effect efferent or afferent arterioles more?
efferent
What happens if Ang II vasoconstricts afferent arterioles?
1) decrease blood flow
2) decrease GFR
3) increase resistance
Are efferent or afferent arterioles more sensitive to Ang II?
efferent arterioles are more sensitive
NSAIDs inhibit _______________ production
prostaglandin
prostaglandins decrease _________
vasoconstriction
T/F: pts with renal disease should not take NSAIDs
TRUE
____________ __________ produces the vasodilator dopamine
proximal tubule
(dopamine is a vasodilator that increases RBF and maintains GFR)
Kidneys MUST maintain ______ (need to get urine and waste out of body)
GFR
renal pressure can fluctuate from _____________ mmHg without any change in RBF or GFR because of autoregulation
80-180 mmHg
What are the two autoregulation mechanisms in the renal system?
1) myogenic response (myo= muscle)
2) tubuloglomerular feedback
What happens with myogenic response?
1) increase pressure systemically
2) increase renal arterial pressure
3) stretch afferent arteriolar walls
4) constrict arterioles of tunica media
5) increase resistance
6) constant RBF and GFR
What happens with tubuloglomerular feedback?
1) increase pressure systemically inistally as renal arterial pressure increases
2) increase RBF and GFR
3) increase flow past the macula densa
4) secrete vasoactive paracrines
5) constrict arterioles
6) increase resistance
7) offset increase in pressure
8) decrease RBF and GFR
What is the first step of urine formation?
glomerular filtration
What is ultrafiltrate?
water and solutes from blood into bomen’s space
What does it mean if there is blood and proteins in the urine?
there is something wrong with filtration membrane
What starts filtration?
starling forces (hydrostatic pressure, oncotic pressure, etc.)
What are the 3 processes for urine formation?
1) filtration
2) absorption
3) secretion
What is the barrier to filtration?
glomerular capillary wall
What are the 3 filtration layers?
1) endothelium of capillary (contains large pores and is simple squamous, fluids/plasma proteins/solutes can all pass through pores, RBCs cannot pass through)
2) basement membrane/basal lamina (stops plasma proteins from passing through)
3) podocytes that surround the capillaries and sit on the glomeruli (foot processes warp around and in between the filtration slits)
In the steady state, fluid pressure and pi are ________
constant
What are the 4 starling forces?
1) glomerular capillary hydrostatic pressure (55 mmHg, is the driving force of filtration and pushes water and solutes into blood plasma through the glomerular filter)
2) glomerular capillary oncotic pressure (pi is approx 30 mmHg, contains plasma proteins and blood cells that displace the water content of the blood in the Bowman’s capsule)
3) Bowman’s space oncotic pressure (IF in space =0 because when there is no proteins there is no pressure, technically not a starling force and is removed from GFR eq
4) Bowman’s capsule hydrostatic pressure (fluid pressure is approx 15 mmHg, bowman’s capsule exerts hydrostatic pressure of its own that pushes against the glomerulus)
What determines filtration pressure?
hydrostatic pressure
Hydrostatic pressure is a result of what?
aortic pressure
What is the main factor affecting GFR?
hydrostatic pressure
What happens if the afferent arterioles are vasoconstricted and increase resistance?
1) decrease renal blood flow
2) decrease hydrostatic pressure
3) decrease GFR
(sympathetic NS and low levels of Ang II can do this)
What happens if the afferent arterioles are dilated and there is no resistance?
1) sympathetic NS is not acting
2) increase renal blood flow
3) increase hydrostatic pressure
4) increase GFR
What happens if the efferent arterioles are constricted?
1) increase resistance in efferent arterioles
2) decrease RBF
3) blood goes backwards (regurg?????)
4) increase hydrostatic pressure
5) increase GFR
What happens if there’s low levels of Ang II in the body?
has a large effect on efferent arterioles (it will increase GFR even though resistance is increased)
will have a smaller effect on afferent arterioles (will increase resistance but decrease GFR)
What happens if there is high levels of Ang II in the body?
will have a large effect on efferent arterioles because they are more sensitive to Ang II
if pt has a high BP, then this will increase resistance and blood will build up in glomerulus, GFR remains constant
may have an increased effect on afferent arterioles, but still minor compared to efferent arterioles
if pt is hemorrhaging, and pt releases high levels of ANG then this will increase resistance, decrease GFR and RBF and limit fluid loss and preserve blood volume
What changes with plasma protein concentration?
pi
What happens if plasma protein concentration increases?
1) increase oncotic pressure
2) more reabsorption
3) decrease hydrostatic pressure
4) less fluid leaving
What happens if plasma protein concentration decreases?
1) changes in fluid pressure can happen if urine flow is blocked (ex: kidney stones)
2) decrease flow and accumulation of urine
3) increase IF space pressure
4) increase hydrostatic pressure of IF space (pushing more fluid in)
