Lecture 44 Renal Glomerular Filtration Flashcards
what direction does the indented surface of the kidney, the hilum face?
faces the spine
what causes a renal colic?
pain in the flank that radiates toward the groin. Its usually sever and commonly called renal calculi. ( kidney stones)
what kidney is lower and why?
the right kidney because the liver is above
where might kidney stones cause pain due to obstruction?
- the junction of the renal pelvis and ureter
- the site where the ureter passes over the pelvic brim
- At the junction between the ureter and the bladder
What is the order of Urine leaving?
the nephrons> renal pelvis> ureter> bladder
The renal cortex has osmolality due to…
plasma
the inner medullary osmolality is increased severalfold ( this hyperosmolarity is responsible for the concentration of urine)
this osmotic gradient is used to recover water that is filtered from the vasculature each day.
what is the average urinary water excretion?
1-2 L per day
In the endocrine function of the kidney what occurs?
hormones are produced.
Erythropoietin- stimulates bone marrow for the production of red blood cells. ( pale skin and anemia if this is an issue)
Renin- converts angiotensinogen to angiotensin I.
Hydoxylates 25 OH to 1,25 OH vitamin D ( bone pain)
What is the homeostatic function of the kidney?
- regulation of extracellular fluid
- regulation of osmolarity
- maintenance of ion balance
- homeostatic regulation of PH
- excretion of wastes ( urea, can have gout)
in kidney failure trouble maintaining blood pressure and hyperkalemia
In polycystic disease where do the cysts form?
within the nephron and progressively enlarge and compress the surrounding tissues, preventing fluid flow through the tubule.
what are the two types of nephrons?
cortical ( functional) 85% and juxtamedullary 15%
the cortex of the nephron consists of what?
proximal and distal convoluted tubules as well as the initial segments of the collecting ducts, bowman’s capsule
the medulla of the nephron consists of what?
consist of long loops of henle and the terminal regions of the collecting ducts
what are juxtamedullary nephrons important for?
urine concentration
what is the functional unit of the kidney and what does it consist of ?
the glomerulus and the renal tubule
The glomerulus is a ______ network and is surrounded by ________, which is continuous with the first tubule of the nephron
capillary network
bowman’s capsule/bowman’s space
what do the tubules of the kidney comprise of?
SLIDE 9 draw it muahahaha
1-proximal convoluted tubule.
2- loop of Henle ( proximal straight tubule, thin descending limb and thick ascending and distal straight tubule)
3. Distal convoluted tubule
what is the blood supply of the kidney?
Renal artery> segmental artery> interlobar artery>arcuate artery> interlobular artery> afferent arteriole> glomerulus> efferent arteriole> peritubular capillaries> interlobular vein> arcuate vein> interlobar vein> segmental vein> Renal vein
Riding Segways interngalactically, an ignorant alien got extremely perverted. ( veins start all over from ignorant backwards)
what is the responsibility of the vasa recta?
keeping the renal medulla hyperosmolar/hypertonic.
very small blood flow.
this small blood flow makes the vasta recta susceptible to ischemia in the setting of hypotension or renal vasoconstriction
The slow flow of oxygen keeps the pO2 of the medulla _____ than that in the cortex. A sustained decrease in renal perfusion may result in ________.
lower
acute renal failure
What makes up the renal corpuscle?
the Glomerulus and the Bowman’s capsule
what does the macula densa do?
chemoreceptor cells in the walls of the distal convoluted tubule which respond to changes in solute concentration os sodium Na
where are juxtaglomerular cells found?
modified smooth muscle cells located in the walls of afferent arterioles they reduce renin
what makes up the juxtaglomerular apparatus?
- Macula densa
- Juxtaglomerular cells
- Mesangial cells.
What is the first step of urine filtration?
ultrafiltration of blood across the glomerular capillaries into Bowman’s space
what makes up the glomerular filtration barrier?
1-endothelial fenestration of glomerular capillaries.
2- Glomerular basement membrane
- fused basal lamina of the endothelial cells and podocytes
-Heparin sulphate repels negatively charged molecules
3- podocyte layer
( visceral layer of the Bowman’s capsule)
- modified epithelial called podocytes, highly ramified.
Primary process> secondary processes> tertiary processes ( pedicels)
- filtration slits between pedicels
Filterability of a molecule is _______ related to their size.
what does a filterability of 1 mean? what does it mean 0?
inversely related
1, then it filters like water into glomerular capillaries for example, water sodium, glucose inulin
0.75 - myoglobin
0 or close to it, it doesn’t filter in like albumin
The size of a plasma protein such as albumin is 6 nm and the pore of the glomerular membrane is about 8 nm, so why doesn’t it filter?
it has to do with the charge. negative charges do not filter in well, but positive charges do.
this makes sense because the glomerular capillary wall has proteoglycans (- charge)
this explains why there is barely any protein found in urine
** tested with dextran graph slide 15)
the glomerular filtration barrier would keep blood and protein molecules in/out of blood?
what happens if you lose the negative charges of the glomerular filtration barrier?
in the blood, the do not filter out.
Minimal change disease, protein molecules spill into the urine because of abnormalities in the capillary wall
why is the disease called minimal change? what would you view ?
because if you send the sample under light microscopy you will not see the changes, you need to use the electron microscope.
the electron microscope is supposed to see separate foot processes ( see pic)
Instead, the glomerular capillary has fused foot processes
A dude is urinating a lot and they found protein in his urine what kidney structure is affected? A. JGA cell B.basement membrane C. Mesengial cell D. Na/K atpase pump E. Smooth muscles in efferent arteriole F. PCT epithelial cell
B basement membrane. the negative charge was affected, minimal change disease caused protein to filter through when they are not supposed to.
what is GFR?
Glomerular filtration rate, it is the net fluid flow across the capillary wall. Normal GFR value for both kidneys is about 125 ml/min
what is the equation for GFR? what drives GFR?
GFR= Kf * delta P GFR= glomerular filtration rate Kf= Glomerular capillary filtration coefficient changeP= Net filtration pressure
PGC= hydrostatic pressure in glomerular capillaries drives it
Wha influences the factors of glomerular filtration ?
GFR= Kf * delta P
Kf= ( filtration coefficient) surface area of glomerular capillaries available
permeability of interface between capillary and Bowman’s capsule
deltaP= ( net filtration pressure)
hydrostatic pressure, oncotic pressure and bowman’s fluid
What occurs when GFR is low? what is the result of it?
renal insufficiency a decline in this means that you are in the stages of chronic kidney disease.
How to calculate delta P in GFR…
What does a positive delta P mean?
what does a negative delta P mean?
what does PBS mean?
piBS?
GFR= Kf * delta P
Favor filtration: positive favors filtraton because it pushes water from capillaries into Bowman’s space (PGC) +60
Favors filtration: piBS= 0, no plasma protein filtered here
opposes filtration or favors reabsorption: negative contains albumin and is ( piGC) -32
opposes filtration or favors reabsorption:Bowman’s space fluid= opposes filtration= -18 PBS
delta P= FAVOR FILTRATION- OPPOSE FILTRATION
look at flash card, ( equation didn’t make sense with answer given)
60-18-32=10
hydrostatic pressure:
oncotic pressure:
pushes
pulls
the hydrostatic pressure in the glomerular capillaries versus the Bowman’s space….
what occurs to the oncotic pressure?
Bowman’s space hydrostatic pressure stays constant
hydrostatic pressure of glomerular capillary decreases/ but oncotic pressure increases
absorption increases
How to calculate Kf in GFR…
GFR= Kf * delta P
what is Kf?
- a measure of the product of hydraulic conductivity and surface area of the glomerular capillaries
- increased Kf raises GFR and decreased Kf reduces GFR
What diseases lower Kf?
chronic uncontrolled hypertension and diabetes mellitus lower Kf by reducing the number of functional glomerular capillaries ( reducing surface area for filtration) or by increasing the thickness of the glomerular capillary membrane
what is the difference between Nephrotic and Nephritic syndrome?
damage to glomerulus can damage filtration coefficient Kf= if it is increased the GFR increases and can lead to any of these…
Nephrotic= excretes too much protein
Nephritic= excretes RBCS hematuria
what occurs if you increase bowman space oncotic pressure?
SLIDE 22
60-18-32+10= 20
Pgc-Pbs-piGc+pibs
piBS is supposed to be 0 but if there is damage more filtration happens at bowmans space.
can lead to nephrotic edema, the fluid will go into interstitial space/ nephrotic syndrome
Nephrotic syndrome can lead to what?
peripheral edema, proteinuria, hyperlipedemia, hypoalbuminemia ( low in plasma)
Kidney stones cause ______ and ______ of the urinary system. what occurs if the bowman’s space has obstruction?
what occurs to the GFR? what disease ?
slide 23
obstruction and dilation..
Hydronephrosis ( distention and dilation of the renal pelvis and calyces) can destroy the kidney… remember there is less filtration so there is basically fluid build up “ hydro= water”
Urinary cholelithiasis.
if bowman’s space has obstruction it leads to an increase of fluid unto the kidney, inflammation= increased hydrostatic pressure.
look at slide. for equation explanation
- less filtration
-decreased GFR ( this is a negative value that is increased)
- less urination, more infections.
- can affect the cortex
- painful urination.
What is the filtration fraction?
represent the loss of protein free fluid into the Bowman’s space, thereby increasing the concentration of protein in the plasma
What is the equation for filtration fraction?
FF= GFR/RPF
FF= filtration fraction
GFR= glomerular filtration rate
RPF=Renal plasma flow
normal is 20%
Filtration fraction affects _____ pressure in the peritubular capillaries.
The_____ the FF the higher the oncotic pressure int he peritubular capillaries.
slide 26
oncotic
higher
opposite is also true low/lower
piC= or peritubular capillary oncotic pressure is the driving force for reabsorption.
piC is the driving force for reabsorption where?
peritubular capillaries
The afferent and efferent arterioles in the kidneys are the sites of largest ______ resistance.
largest vascular resistance.
blood pressure decreases a lot here.
What happens if you vasoconstrict the renal capillary ?
slide
pressure upstream increases,
pressure downstream and blood flow decrease downstream
What happens with vasodilation of the renal capillary ?
slide
decreased pressure upstream
increased pressure and blood flow downstream
what occurs to glomerular capillaries if you have afferent arteriole vasoconstriction ?
GFR?
hydrostatic pressure?
the hydrostatic pressure of the glomerular capillaries decreases..
GFR will decrease
peritubular hydrostatic pressure will also decrease
decreased renal plasma/blood flow
aka increased afferent arteriolar resistance decreases the hydrostatic pressure of everything after
what can prevent this?
vasodilators like PGE2, PGI2, Bradykinin
what can cause vasodilation of afferent arterioles?
PGE2, PGI2, Bradykinin
GFR increases
increase in hydrostatic pressure of glomerular capillaries.
increase in hydrostatic pressure of peritubular capillaries,
increase in renal plasma/blood flow
what occurs to glomerular capillaries if you have efferent arteriole vasoconstriction ?
increase in hydrostatic pressure of glomuerual capillaries
GFR increases
decrease in hydrostatic pressure of peritubular capillaries ( look at pic to understand)
decrease in renal plasma/blood flow .
what occurs to glomerular capillaries if you have efferent arteriole vasodilation ?
decrease in hydrostatic pressure of glomerular capillaries
increase in hydrostatic pressure of peritubular capillaries.
increase in renal plasma/blood flow.
decreased GFR
Aspirin is given to a patient and this causes inhibition of prostaglandins. urine output of patient is decreased a lot and there is absence of proteinuria. what mechanism best explains the reduced urine after aspirin?
A. constriction of afferent arteriole and increase GFR
B. dilation of afferent arteriole and increase GFR
C. Constriction of afferent arteriole and decrease GFR
D. dilation of afferent arteriole and decrease GFR
E. constriction of efferent arteriole and decrease GFR
C. aspirin is a vasoconstrictor
what does auto regulation do in the kidneys?
how do high and low GFR affect reabsorption?
it keeps GFR constant, and allows precise control of renal excretion of water and solutes.
If GFR is too high needed substances cannot be reabsorbed too quickly enough and is lost in the urine
IF GFR is too low too much reabsorption occurs and it also absorbs a waste product such as urea. ( gout can happen)
renal blood flow is relatively stable over mean arterial pressures (MAP) of 80-180
What is myogenic response?
changes the resistance of afferent arteriole by intrinsically constricting smooth muscle when stretched.
what is tuboglumerular feedback? ( TGF)
( mechanism that changes resistnace of the afferent arterioles) an auto regulatory mechanism mediated by the juxtaglomerular apparatus that adjusts renal blood flow and glomerular filtration to optimize fluid flow through the renal tubule.
Granule cells contain _____ which is released into circulation when tubule flow rate is low.
renin
what does adenosine cause in the afferent arteriole and efferent arteriole?
afferent= constriction efferent= dialtion
see slide 34 to learn that pathway thing… ( I was tired )
what does angiotensin cause in efferent arterioles?
vasoconstriction
