Term
5 generalized fxns of the kidney
Primary fxn?
Other functions:
Regulation of ____
Reglation of ____
Regulation of ____
Produce and secrete ____ |
|
Definition
Primary fxn: excretion of waste
Regulate body fluid osmolality and volume
Regulate electrolyte balance
Regulate acid-base balance in resp system
Produce and secrete hormones |
|
|
Term
What ions are regulated by kidney?
If there is a positive ion balance, than what is the relationship between excretion and intake?
If there is a negative balance?
What can happen if K+ levels are too hgih? |
|
Definition
Na+, K+, Cl-, HCO3-, H+, Ca2+, Pi
Positive balance (hyper) = excretion < intake
Negative balance (hypo) = excretion > intake
K levels too high, can go into asystole |
|
|
Term
| What are some waste products of the kidneys? |
|
Definition
| urea, uric acid, creatine, end products of Hb metabolism, metabolites of hormones |
|
|
Term
3 hormones produced by the kidney
1. ____ - important for Na/K balance and thus BP control
2. ____ - important for normal absorption of Ca from the GI tract and deposition of Ca in bone.
3. ____ - stimulates RBC formation by the bone marrow |
|
Definition
renin
calcitriol
erythropoetin |
|
|
Term
| Why might someone with renal failure be anemic? |
|
Definition
| Becuase they aren't producing enoguh erythropoeitin |
|
|
Term
|
Definition
renal corpuscle
proximal tubule
loop of henle
distal tubules
collecting system |
|
|
Term
The junction of the loop of henle and the distal tubule that passes between the afferent and efferent is the ____, which is important for detecting the amt of sodium in the filtrate.
This structure "talks" to the ____ |
|
Definition
macula densa
afferent arteriole |
|
|
Term
|
Definition
descending thin limb
ascending thin limb (long loops)
Thick ascending limb |
|
|
Term
In the nephron, the ___ extends from the macula densa to the collecting tubule.
The cortical collecting duct enters the medulla to become the ____ and then it becomes the ___ |
|
Definition
distal tubule (DT)
Cortical collecting duct --> outer medullary collecting duct --> inner medullary collecting duct |
|
|
Term
About 70% of absorption happens in the ____ of the nephron because of the infoldings and brush border located here
___ are located in the infoldings of the basolateral membrane on the outside of this strucutre |
|
Definition
proximal tubule
Na/K ATPase |
|
|
Term
two types of cells in the collecting tubules
1. ___ - moderate invaginations of the basolateral membrane. Contain Na/K ATPases. Serve a role in reabsorption of __ and secretion of ___.
2. ___ - play a role in acid-base balance. Have a lot of mitochondria. 2 types:
___ - secrete H+ (acid) and reabsorb HCO3-
___ - secrete HCO3- |
|
Definition
1. principal cells, absorption of NaCl and secretion of K
2. Intercalated cells - alpha and beta |
|
|
Term
Two types of nephrons:
1. Superficial: efferent arteriole branches to form ____ that surround the nephron and supply O2 and nutrients, deliver substances to nephron for secretion, and serve as a pathway for glucose reabsorption
2. ____: have a long loop of henle, efferent arterioles contains vasa recta, and it dilutes or concentrates urine |
|
Definition
peritubular capillaries
juxtamedullary |
|
|
Term
Renal corpuscle:
1. Produces ____ from glomerular capillaries to bowman's space
2. Fenestrated capillaries are surrounded by ____ (Bowman epithelial cells)
3. Epithelial cells are covered by a ____, which has a negative ion charge associated with it
These 3 layers form the ____ |
|
Definition
ultrafiltrate
podocytes
glycoprotein basement membrane
filtration barrier |
|
|
Term
| ____ are like sieves that pick out the important stuff from the filtrate |
|
Definition
|
|
Term
The filtration barrier cosists of what 3 parts?
It is not permeable to what 3 things? |
|
Definition
fenestrated capillary endothelium
basement membrane
foot process of podocytes
Impermeable to RBCs, WBCs, and platelets
|
|
|
Term
| What two things keep albumin (large, negatively charged ion) out of the glomerular filtrate? |
|
Definition
| basement membrane, endothelial cells |
|
|
Term
What would lots of WBCs in the urine indicate?
What would lots of RBCs or albumin in the urine indicate? |
|
Definition
WBCs - kindey infection
RBCs or albumin - filtration barrier isn't working |
|
|
Term
| Some diseases such as ___ decrease the ability of the membrane to repel negative charges and thus break down the filtration barrier and protein will come out through urine. How can you assess if glycosylation is a problem in a patient with this disease? |
|
Definition
|
|
Term
Mesangial cells:
Are ___ cells
Provide structural support for the ____
Secrete the _____
Can exhibit ____ activity
Secrete ___ & ____
Influences GFR by regulating ____ |
|
Definition
smooth muscle
glomerular capillaries
extracellular matrix
phagocytotic activity
prostaglandins and pro-flammatory cytokines
blood flow
|
|
|
Term
Juxtaglomerular apparatus:
Important for ___ feedback
Autoregulation of __ & __
Made up of what 3 things? |
|
Definition
tubuloglomerular feedback
RBF & GFR
macula densa, extraglomerular mesangial cells, renin-angiotensin II producing granular cells |
|
|
Term
Renin-angiotensin II producing granular cells line the ___ in the juxtaglomerular apparatus.
___ cells may be important for the secretion of the erythropoietin |
|
Definition
line afferent tubules
lacis |
|
|
Term
Innervation of the kidney:
Sympathetic nerve fibers from the ___ plexus (aorticorenal ganglia)
- release __ & ____
No ___ innervations |
|
Definition
celiac, NE & dopamine
no parasympathetic innervation |
|
|
Term
Norepinephrine:
increases/decreases renin to conserve fluid
increases/decreases Na reabsorption to conserve fluid |
|
Definition
|
|
Term
| 4 processes of the nephron |
|
Definition
1. glomerular capillaries filter everything out
2. reabsorb important nutrients into peritubular capillaries
3. secrete back into the filtrate
4. excrete waste |
|
|
Term
Forces behind ultrafiltration are ___ forces
GFR and RBF are held in a narrow range by ___ by the afferent and efferent arterioles |
|
Definition
starling's forces
autoregulation |
|
|
Term
Determinants of ultrafiltrate composition
Radius smaller than ___ Angstrums are freely filtered
Radius greater than __ angstrums are not filtered
Pos/neg charged ions are more readily filtered? |
|
Definition
glomerular filtration barrier:
20 A, 42 A
positive
|
|
|
Term
| In ____, immune complexes interact with complement in the blood, attract leukocytes, which relase proteolytic enzymes that produce holes in the capillaries allowing formed elements (blood cells) and plasma proteins (albumin) to pass more readily through the membrane |
|
Definition
|
|
Term
____ pressure promotes fluid movement into the bowman's capsule out of the glomerulus. it is the ONLY force favoring filtraiton.
___ & ___ pressures oppose glomerular filtration (draw protein out), although the first one is inappreciable unless an a lot of portein is filtered as in glomerulonephritis or prolonged DM |
|
Definition
Hydrostatic pressure of glomerular capillary (Pgc)
Hydrostatic pressure of fluid in bowman's space (Pbs) and oncotic pressur ein teh glomerular capillary (pigc) |
|
|
Term
| Why is there no oncotic pressure in bowman's capsule? |
|
Definition
|
|
Term
Filtration occurs in ___ capillaries
Reabsorption occurs in ___ capillaries |
|
Definition
|
|
Term
Two tendencies as the ultrafiltrate passes through the nephron (from afferent to efferent arterioles):
Hydrostatic pressure of the glomerular capillary (Pgc) increases/decreases slightly through the capillary (resistance)
Oncotic pressure in glomerular capillary (pigc) increases/decreases along the capillary (loss of fluid through ultrafiltration) |
|
Definition
|
|
Term
Pressures in circulation:
pressure of glomerular capillaries in afferent v. efferent
Pressure in bowman's
oncotic presssure in bowmans
Oncotic pressure
Ultrafiltrate pressure |
|
Definition
Pgc: Afferent 60 mmHg, Efferent 58 mmHg
Pbs: -15, -15
oncotic (bowmans): 0,0
Oncotic (glomerular): -28, -35
Ultrafiltrate: 17, 8 |
|
|
Term
Ways to alter Pgc (Starling's Pressures)
Change afferent arteriolar resistance:
Decreasing resistance does what to Pgc and GFR?
Increasing resistance does what?
Change efferent arteriolar resistance:
Decreasing and increasing?
Change renal arteriolar pressure:
Increasing blood pressure (increasing flow) does what to transient Pgc and GFR?
Decreasing bp? |
|
Definition
Afferent arterioles:
Decrease resistance = increased Pgc and Gfr
Increase resistance = decreased Pgc and GFR
Efferent Arterioles:
Decreased resistance = decreased Pgc and Gfr
Increased resistnace = incrased Pgc and GFR
Renal Arteriolar pressure:
Increasing BP (and thus flow) = increased transient Pgc and GFR
Decreasing BP = decreased transent Pgc and GFR
** GFR changes based on what Pgc does ** |
|
|
Term
| 2 ways the renal system can regulate BP |
|
Definition
renin/angiotensin/aldosterone system
changing fluid volume (increase in fluid = increase in BP) |
|
|
Term
Importance of RBF:
Indirectly determines ___
Modifies the rate of solute and water reabsorption by the ____
Participates in the conentration and diution of urine
Delivers __, ___, __ to the cells
Delivers substrates for ____ |
|
Definition
GFR
proximal tubules
O2, nutrients, hormones
excretion |
|
|
Term
| What is PAH and what is it used for? |
|
Definition
PAH - P-aminohuppurate
The clearance of PAH nearly equals Renal Plsma Flow
It is filtered and vigorously secreted so that <10% is found in the renal vein
It has a 0.91-1 extraction ratio, which means its a great indicator of RPF |
|
|
Term
| What is normal renal blood flow? |
|
Definition
| About 700 ml/min -- about 20% of CO goes through kidneys, so if CO is 3.6 L/min, than RBF should be about 700 ml/min |
|
|
Term
| How do you effectively look at renal blood flow? |
|
Definition
|
|
Term
| Which has a higher RBF, PAH or anything else? |
|
Definition
|
|
Term
| How does RBF & GFR remain constant am MAP ranges between 90-180 mmHg? |
|
Definition
| Autoregulation via changes in vascular resistance (vasomotion) |
|
|
Term
| 2 mechanisms for autoregulation in RGF and GFR control with changing MAP |
|
Definition
1. response to arterial pressure (myogenic)
2. Response to change in NaCl in intertubular fluid (tubuloglomerular feedback in macula densa)
Both regulate the radius of AFFERENT arterioles |
|
|
Term
| What is the autoregulation response in the afferent arterioles if there is too much NaCl in the intertubular fluid? |
|
Definition
|
|
Term
How does the tubuloglomerular feedback of autoregulation of GFR work?
1. Concentraiton of NaCl is sensed by the ___ in the JG apparatus.
2. A signal is generated to the ____ to adjust resistance and GFR
Response:
increase GFR = increased/decreased NaCl in macula densa = increased/decreased formation and released of ATP and adenosine? = vasodilation or constriction? of afferent arteriole = Decreased GFR |
|
Definition
macula densa
afferent arterioles
increased Nacl
Increased ATP/adenosine
Vasoconstriction |
|
|
Term
Autoregulation:
A fall in ATP and adenosine cause vasodilation of afferent arterioles
Then __ falls, causing vasoconstriction
Then ___ enhances the vasoconstriction
Then the ____ may relesase paracrine vasodilators (NO) or constrictors (ATP or adenosine) as needed |
|
Definition
NO
angiotensin II
macula densa |
|
|
Term
| In general, NO is a vasoconstrictor/dilator and Angiotensin II is a vasoconstrictor/dilator of afferent arterioles |
|
Definition
NO = dilator
ANgiotensin II = constrictor |
|
|
Term
How does sympathetic nerve activity affect RBF and GFR?
Ne and Epi
Renalase |
|
Definition
NE and Epinephrine are vasoconstrictors at alpha 1 adenoreceptors on afferent arterioles: They decrease GFR and RBF. Are released during stress response
Renalase: a catecholamine-metabolizing hormone that degrades catecholamines (like Ne and epi) |
|
|
Term
4 vasoconstrictors:
All reduce GFR and RBF
What is each's release stimulated by?
What reverses each? |
|
Definition
Sympathetic NS (NE and Epi) - stimulated by decreased in ECFV. Reversed by renalase
Angiotensin II - stimulated by decrease in ECFV. Reversed by increase in BP
Endothelin - stimulated by stretch receptors, A-II, bradkinin, epinephrine, and decrease in ECFV.
Adenosine |
|
|
Term
4 Vasodilators.
All increase GFR and RBF
What is the release of each stimulated by? |
|
Definition
Prostaglandins - stimulated by decrease in ECFV, increase in shear stress, and A-II
NO - stimulated by increase in shear stress, acetylcholine, histamine, bradykinin, and ATP
Bradykinin - stimulated by increase in prostaglandin, and decrease in ACE
Natriuretic peptides - stimulated by increase in ECFV |
|
|
Term
| What vasodilator is important in the diagnosis of CHF? |
|
Definition
|
|
Term
2 natriuretic peptides:
Responds to excessive stretching of the ___
Effect on vascular resistance?
Effect on central venous pressure?
Effect on excretion of sodium (natriuresis)?
Effect on CO?
Effect Blood volume?
Effect on afferent arterioles?
Effect on efferent arterioles?
Effect on glomerular hydrostatic pressure? |
|
Definition
ANP - atrial natriuretic peptide
BNP - brain natriuretic peptide
decrease systemic vascular resistance
decrease central venous pressure
increase natriuresis
decrease CO
decrease blood volume
Dilate afferents
Constrict efferents
increase glomerular hydrostatic pressure
^ all of which increase GFR ^ |
|
|
Term
BNP is used to screen for ___.
An increase/decrease in BNP is worse for CHF prognosis
What BNP level is "normal"? |
|
Definition
CHF
increase
BNP < 100 pg/ml is normal |
|
|
Term
What are three drugs that increase GFR and RBF?
1. ___ - simply increases GFR and RBF
2. ___ - modulates RBF during rest and inflammation by decreasing resistance in both afferent and efferent arterioles. Has little effect on GFR because BOTH afferents and efferents are dilated.
3. ___ - produced in poximal tubules. Increase RBF and decrease renin secretion (opposite of NE) |
|
Definition
| Gluocorticoids, histamine, dopamine |
|
|
Term
| The driving force for glomerular filtration is ____. |
|
Definition
| glomerular capillary hydrostatic pressure |
|
|
Term
| The measure of the rate of excretion of a substance is called it's ____. It is based on Fick's principles. |
|
Definition
|
|
Term
| The input of a substance into the kidney (Px x GFR) is referred to as the ___. |
|
Definition
|
|
Term
| If a pt with DM has a glucose level of 300 mg/ml but their transportation maximum (Tm) is only 200 mg/ml, shat will happen? |
|
Definition
| They will excrete the extra 100 mg/ml through their urine (glucosuria) |
|
|
Term
| What is the "gold standard" for measure GFR because it's clearance is equal to GFR? |
|
Definition
|
|
Term
___ is a product of muscle metabolism that is used clinically to measure GFR
It has a relatively steady concentraiton of ___ mg/dl
Approximately none is reabsorbed, secreted, or metabolized by the nephron
The validity of this substance for kidney funxtion estimates decreases as kidney fxn decreases, thus other test must be done in renal failure pts |
|
Definition
|
|
Term
| The portion of plasma entering the kidneys that is filtered (about 90%) is called the ____ |
|
Definition
filtration fraction = GFR/RPF
Normal is 0.15-0.2 |
|
|
Term
The first step in glomerular filtration is the ____
What are normal values for this in males v. females? |
|
Definition
ultrafiltration
Males: 90-140 ml/min
Females: 80-124 ml/min |
|
|
Term
What does each plasma creatinine level indicate?
<1.2 mg/dl
1.3-1.6 mg/dl
>1.7 mg/dl |
|
Definition
<1.2 - normal
1.3-1.6 - borderline. needs to be checked frequently. Normal for body builders.
>1.7 - renal failure |
|
|
Term
BUN
Normal levels?
What does high BUN indicate? |
|
Definition
< 20 mg/dl
high BUN indicates renal failure, dehydration, urinary obstruction, starvation, or high protein diet |
|
|
Term
| 3 basic fxns of urine formation |
|
Definition
ultrafiltration of plasma
reabsoprtion of water and solutes from ultrafiltrate
secretion |
|
|
Term
| How does Ouabain poison someone? |
|
Definition
| screws up Na/K ATPase and throws off Na gradient |
|
|
Term
| How is Na absorption different in the proximal v. distal half of the proximal tubule? |
|
Definition
Proximal 1/2: absorbed mainly wtih HCO3-
- H+ antiporter
Several symporters
Distal 1/2: Absorbed with Cl- |
|
|
Term
| Transcellular v. Paracellular routes of Na reabsorption in the distal half of the proximal tubule |
|
Definition
Transcellular: Luminal transport - parallel operation of Na/H antiporter and one or more Cl/anion antiporters
- Na leaves by Na/K ATPase
- Cl leaves by K/Cl symporter
Paracellular route: Rise is tubular Cl favors movement of Cl from lumen across tight junctions into the lateral space |
|
|
Term
| An increase in fluid in the interstitium would increase/decrease hydrostatic pressure, which would increase/decrease movement of water into the capillaries |
|
Definition
|
|
Term
| Protein urine levels of ___ signal kidney disease? |
|
Definition
| +3-4 (really, just above trace amount) |
|
|
Term
| How is protein absorbed by the Proximal tubules? |
|
Definition
|
|
Term
| Organic anions have a high/low transport rate with a high/low specificity |
|
Definition
|
|
Term
| ___ is a mechanism to get rid of a substance and increase the concentration in the tubular fluid |
|
Definition
|
|
Term
What part of the nephron?
Reabsorbs about 25% of filtered NaCl and 15% of filtered H2O
Reabsorption of ___ happens in only the ascending limbs
Reabsorption of water happens only in the descending thin limbs. |
|
Definition
|
|
Term
| What kind of drug is thiazide? |
|
Definition
|
|
Term
As the tubular fluid in the ascending limb returns to the kidney cortex, the NaCl diffuses out of the tubule into the interstitium.
What happens to the osmolality of the fluid? |
|
Definition
|
|
Term
The Ascending limb of the loop of henle reabsorbs NaCL, however the thin and thick limbs do so differently.
How so? |
|
Definition
Thin limb - passive
Thick limb - active via Na/K ATPase and 2Cl symporter |
|
|
Term
The Na/K/2Cl- symporter is blocked by what drug?
Patients with Bartter syndrome have a decrease in this protein naturally and therefore experience salt wasting (dcereased absorption of NaCl) hypokalemic metabolic alkalosis |
|
Definition
|
|
Term
| What effects would an increase in NaCl transport have on the voltage in the lumen? |
|
Definition
| increase positive voltage |
|
|
Term
| The ___ and ___ (parts of nephron) reabsorb about 8% of filtred NaCl, secrete variable amounts of K+, and reabsorb variable amounts of H2O. They are under control of ADH. |
|
Definition
| distal tubule and collecting ducts |
|
|
Term
The inital segment of the distal tubule is sensitive to thiazide-type drugs. What does this mean?
Gitelman syndrome is the lack of the Na/K/Cl symporter and thus results in these symptoms PLUS hypocalciuria |
|
Definition
| diuretic - makes you pee a lot |
|
|
Term
The later segments of the distal tubule and collecting duct have two types of cells:
___ - reabsorb NaCl and H2O and secrete K+. Dependent on Na/K ATPase in BL membrane
___ - secrete either H+ or HCO3- for acid-base balance. Reabsorb K+ through H/K ATPase on apical membrane |
|
Definition
principle cells
intercalated cels |
|
|
Term
____ - a disease in which there is hyperactivity of the ENaC channel enough to result in retention of Na and fluid, resulting in HTN. Also, there is a decrease in serum potassium resulting in hypokalemic metabolic acidosis.
Treatment? |
|
Definition
liddle syndrome
Treatment: reduce Na intake or use amiloride to block ENaC channels |
|
|
Term
| Variable amounts of water are absorbed across the principlec cells in the distal tubule. It is mediated by __ on the apical membrane and __ & __ on the BL membrane. |
|
Definition
|
|
Term
K+ secretion happens in the __ cells of the distal tubule.
K+ reabsoprtion happens in the __ cells of the distal tubule. |
|
Definition
|
|
Term
| Increased/decreased ECFV stimulates the renin-angiotensin-aldosterone system? |
|
Definition
|
|
Term
| Angiotensin II stimulates absorption of __ & ___ |
|
Definition
|
|
Term
Aldosterone stimulates the reabsoprtion of ___ and the secretion of ___
By increasing the amount of Na/Cl
By increasing the Na/K ATPase in BL membrane
Increasing the number of sodium channels on the apical membrane of principal cells |
|
Definition
|
|
Term
___ release is stimulated by hyperkalemia and angiotensin II
It is inhibited by hypokalemia and natriuretic peptides
One of its fxn is to secrete K |
|
Definition
|
|
Term
____ - inhibit NaCl and water reabsorption
Secretion is stimulated by increased BP and ECFV
Actions are to decrease BP and ECFV via urinary excretion of NaCl and H2O
Inhibits the action of ADH
Are considered the body's "water pill" |
|
Definition
|
|
Term
| Catecholamines are secreted at increased/decreased ECFV? |
|
Definition
|
|
Term
Dopamine is released at increased/decreased ECFV?
It inhibits the reabsoprtion of NaCl and water in proximal tubule and thus promotes diuresis |
|
Definition
|
|
Term
| Adenomedullin is diuretic/antidiuretic |
|
Definition
|
|
Term
ADH is secreted from ___
It is stimulated by increased/decreased osmolality or increased/decreased ECFV
It increases/decresases permeability of CD to H2O |
|
Definition
posterior pituitary
increased, decreased
increased |
|
|
Term
Starling's forces:
Which 2 forces are in favor of movement into blood?
Which 2 forces are against movement into blood?
Which one is directly related to filtration fraction? |
|
Definition
oncotic pressure in peritubular capillaries
pressure in interstitium
onctotic pressure in intersitium
pressure in peritubular capillaries
oncotic pressure in peritubular capillaries is directly related to filtration fraction:
decrease in Filtration Fraction = decreased in GFR (constant RBF) = decrease in oncotic peritubular |
|
|
Term
G-T balance concept:
Reabsorption of Na and H2O increase in proportion to teh increase in ___ and ____
Similar to tubuloglomerular feedback |
|
Definition
| GFR and filtered load of Na |
|
|
