Keef Overview of Renal physiology Flashcards
(blank) percent of nephrons are cortical while (blank) are juxtamedullary
85%, 15%
What is the distal tubule right next to?
the glomerular capillary (glomerulus)
The more resistance you have the less (blank)
permeable
The expression pattern of (blank) along the nephron determines the relative ability of water and particles to move via a paracellular route.
tight junction proteins
What part of the nephron has the most resistance?
The collecting duct
(blank) are key integral membrane proteins that provide the barrier function and permit selective paracellular transport in the nephron.
Claudins
With injury to the nephron, multiple signaling pathways are activated, resulting in phosphorylation of (blank) and disruption of the complex.
Tight junction proteins
resistance goes up from what end to what end of the nephron and is dependent on the properties of the what?.
It gets more resistance from beginning (glomerulus) all the way to the end (collecting duct).
Dependent on properties of in between cells
The permeability of tight junctions between epithelial cells (blank) throughout the nephron
differs
The permeability of tight junctions between epithelial cells differs throughout the nephron. It is determined by the expression levels of (blank) that project into the paracellular space between cells. Disruption of these proteins through injury, disease or mutation can lead to serious disruption of normal renal function.
various proteins
Arginine vasopression is another name for what?
antidiuretic hormone
Antidiuretic hormone (ADH) aka arginine vasopressin (AVP) greatly increases water permeability in the collecting duct by recruiting (blank)
water channels (aquaporins).
Antidiuretic hormone (ADH) aka arginine vasopressin (AVP) greatly increases water permeability in the (blank) by recruiting water channels (aquaporins).
collecting duct
Different parts of the nephron express different (blank)
aquaporins (AQP).
Are ALL aquaporins recruited by ADH?
Which ones are recruited by ADH?
No
AQP2,3,4
What aquaporins are found in the proximal tubule?
AQP1, 7
(blank) surround all parts of the nephron and a subset of these supplying the Juxtamedullary nephrons are referred to as the “vasa recta”
Peritubular capillaries
Peritubular capillaries surround all parts of the nephron and a subset of these supplying the Juxtamedullary nephrons are referred to as the (blank)
“vasa recta”
Which have longer loops of henley, juxtamedullary or cortical nephrons?
juxtamedullary
How many layers of epithelium does bowmens capsule have?
one layer
Which creates the osmotic gradient, juxtamedullary or cortical nephrons?
the juxtamedullary
Where are vasa recta found? Is it high or low pressure?
in the juxtamedullary nephrons
Low pressure
Explain the blood flow of the cortical nephron
renal artery->afferent arteriole(resistance)->glomeruls (high pressure)->efferent arteriole (resistance)-> peritubular capillaries (low pressure) ->renal vein
Explain the blood flow of the juxtamedullary nephron
renal artery->afferent arteriole(resistance)->glomeruls (high pressure)->efferent arteriole (resistance)-> Blood flow splits between Peritubular capillaries(low pressure) and Vasa Recta (most blood flows here, low pressure)-> renal vein
Where is the majority of blood flow and how much RBF goes here?
90% to cortex
10% to medulla
What is the first point of resistance?
afferent arteriole
What is the juxtaglomeruluar apparatus?
it is the point where the distal convuluted tubule is in close proximity to the glomerulus
What are the specialized granular cells of the afferent arterioles? What do they secrete?
juxtaglomerular cells
renin
What are part of the juxtaglomerular apparatus and sense the level of flow?
macula densa cells
(blank) cells are used as feedback mechanisms to regulate flow via renin release
macula densa cells
(blank) is a mechanism that serves to maintain a relatively constant Glomerular filtration rate by sensing NaCl levels in the distal nephron and releasing substances that feed back onto the glomerulus to modify arteriolar resistance.
tubuloglomerular feedback (TGF)
If you have low amount of salt what is your GFR like? (low tubular flow)
you have low GFR, salt levels and GFR is directly proportional
If you have decreased arterial pressure in the nephron due to blood loss or something, what will happen?
you will have decreased glomerular hydrostatic pressure which will then decrease your GFR, which the macula densa will sense via the low levels of salt, the macula densa will then increase renin secretion to case EFFERENT constriction and AFFERENT dialation to increase glomerular filtration rate.
If you have decreased arterial pressure in the nephron due to blood loss or something, what will happen?
you will have decreased glomerular hydrostatic pressure which will then decrease your GFR, which the macula densa will sense via the low levels of salt, the macula densa will then increase renin secretion to case EFFERENT constriction and AFFERENT dialation to increase glomerular filtration rate.
What are the two cell types laying outside of the epithelium of the affarent and efferent arteriole?
smooth muscl cells that are granular cells (juxtaglomerular cells) and outside of the SMC cells are extraglomerular mesangeal cells
What happens when you have increase in arterial pressure (tubular flow and increase in salt delivery) from the distal convoluted tubule?
Na+-K+-2Cl-cotransporter (NKCC2) sense the extra salt and bring it into the macula densa. The macula densa senses this amount of salt and WITH ATP creates adenosine. Adenosine then binds to adenosine receptors on the mesangeal cells of the arterioles. The mesangeal cells then increases amount of Ca, the Ca2+ propogates a signal via gap junctions to the granular cells and afferent arterioles. The signal tells afferent arterioles to vasoconstrict and it inhibits renin release.
If you want the most glomluar filtration possible, what do you want to do to your afferent arteriole and your efferent arteriole?
you want to dialate your affarent and constrict your efferent
If you want the most glomluar filtration possible, what do you want to do to your afferent arteriole and your efferent arteriole?
you want to dialate your affarent and constrict your efferent
When we think of arterial pressure in terms of glomerular filtration rate, how are they proportional?
directly
i. e low GFR, low pressure
i. e high GFR, high pressure
What does NKC22 do?
It serves to extract sodium, potassium, and chloride from the urine (inside distal tubule) into the macula densa
To move sodium out of the macula densa what do you need?
ATP
juxtaglomerular cells harbor (blank) receptors. When stimulated by epinephrine or norepinephrine, these receptors induce the secretion of renin
β1 adrenergic
If you stimulate a Mesangeal cell with adenosine what does it do the the arterioles?
constricts afferent and telll JC cells to stop secreting renin to the efferent arteriole which dialates it.
Does renin release affect the afferent arteriole or the efferent?
the efferent!
Does renin release affect the afferent arteriole or the efferent?
the efferent!
So if you have increased calcium propagation will you have increased GFR or decreased?
decreased
So if you have increased calcium propagation will you have increased GFR or decreased?
decreased
What does this describe?
↑Tubular flow →↑NaCl delivery →↑Na/K/Cl transport →↑Na/K transport →↑ADO → ↑ Ra & ↓renin
Increased GFR resulting in lower GFR
pressure falls depending on (blank) for arterioles
resistances
the pressure that is in the (blank) will determine how much water or plasma will go into the kindeys and determine GFR).
glomerulus
When looking at a pressure profile for renal circulation why do you have a plateau?
Due to the two arterioles surrounding the capillary bed keeping the pressure up to allow for filtration
Why is the second capillary bed (peritubular capillary) such a low pressure capillary bed?
to allow for reabsorption (low pressure due to two passes through arterioles which give a lot of resistance)
In renal circulation what is the high pressure capillary bed, which is the low
glomerulus,
peritubular
What is the relationship between blood flow, pressure and resistance?
Blood flow= Pressure gradient (Renal artery-renal vein)/ resistance (Ra + Re)
If you contract either an afferent or efferent arteriole what will happen to flow?
you will reduce flow do to the increase in resistance (remember they are inversely proportional)
If you decrease your afferent arteriole resistance (dialate it) what will happen to RBF, pressure in the glomerulus, and Glomerular filtration?
Increase RBF, increase pressure, increase GFR
If you increase your afferent arteriole resistance (constrict) what will happen to RBF,pressure in the glomerulus, and Glomerular filtration?
Decreased RBF, decreased pressure in the glomerulus, decreased GFR
If you increase your efferent arteriole resistance (constrict) what will happen to RBF,pressure in the glomerulus, and Glomerular filtration?
Decrease RBF, increase pressure in your glomerulus, and you will increase GFR
If you decrease your efferent arteriole resistance (dialate) what will happen to RBF,pressure in the glomerulus, and Glomerular filtration?
Increase RBF, decrease pressure in the glomerulus, decrease GFR
What has a greater affect on glomular filtration rate, the efferent arteriole or the affarent?
afferent!
If you have an increase in resistance (contraction) of the efferent arteriole what will happen to your filtration factor?
If you have a decrease in efferent resistance (dilate) what will happen to your filtration fraction?
You will increase your filtration fraction
You will decrease your filtration fraction
If you have an increase in resistance (contraction) of the efferent arteriole what will happen to your filtration factor?
If you have a decrease in efferent resistance (dilate) what will happen to your filtration fraction?
You will increase your filtration fraction
You will decrease your filtration fraction
What is the equation for filtration fraction?
GFR (ml/min) divided by Renal Plasma flow (ml/min)
What is the intrinsic ability of the kidney to adjust vascular resistance to maintain blood flow at a relatively constant level when perfusion pressure changes?
Autoregulation
With autregulation of the blood flow in the kidney, when you get increased difference in pressure you must increase resistance to maintain the flow, what else are you maintaining by doing this?
GFR (glomular filtration rate)
What is the most important arteriole for autoregulation?
afferent arteriole
What is the myogenic response?
What is this important for?
sensing stretch causes constriction (i.e stretch the afferent arteriole and it responds by contracting)
important for autoregulation
What are the 2 primary mechanisms underlying autoregulation of renal blood flow and GFR?
Myogenic response (increased stretch, increased constricition and increased resistance), and tubuloglomerular feedback(i.e increased arterial pressure increase affarent resistance)
Does autoregulation involve predominantly the post-glomerular efferent arteriole?
NO!
Does autoregulation involve feeback from the macula densa to the affarent arteriole?
yes
Is autoregulation independent of the sympathetic nervous system?
Yes
Does autoregulation maintain constant blood flow and FR under varying arterial pressure?
yes : )
What are 2 factors that modify RBF?
Nerves and hormones (RAAS)
When do you initiate RAAS?
when blood volume or pressure is low (or perceived as low)
What 3 factors regulate renin release?
1) Decreased stretch of afferent arteriole
2) Decreased NaCl delivery to macula densa
(decreased flow of salt in the ascending limb of the loop of henley)
3) Increased sympathetic activity
Changes in renin release are associated with a decrease in (blank) or (blank).
volume or pressure
Changes in renin release are associated with a decrease in (blank) or (blank).
volume or pressure
What is angiotensin’s goal?
to give you salty water and therefore increase your blood volume and to contract arterioles (goal is to increase blood pressure)
What does this:
Contracts arterioles, makes you thirsty, increase ADH secretion by brain to increase water retenetion, stimulates sympathetics to release NE which will constrict arterioles, stimlates adrenal gland to secrete aldosterone which will give you sodium retention as well as NE and E
Renin, angiotensin, aldosterone system
What is this?
Abrupt loss of kidney function that results in the retention of urea and other nitrogenous waste products and in the dysregulation of extracellular volume and electrolytes.
acute renal failure
What is secondary hyperaldosteronism?
it is when you have renal artery stenosis giving perceived low blood pressure to baroreceptors which increase renin release and therefore aldosterone release
What is secondary hyperaldosterism?
it is when you have renal artery stenosis giving perceived low blood pressure to baroreceptors which increase renin release and therefore aldosterone release
What shouldnt you give to a patient with renal artery stenosis?
Explain the mechanism.
ace inhibitor
Low BP in kidney acts on barorecptors to increase renin release-> increase angiotensin and aldosterone-> which will allow for maintanance of GFR. If you put an ace inhibitor in it will block the formation of angiotension II and aldosterone which will result in decreased GFR and therefore acute renal failure.
As renal blood flow increase, (blank) also increases.
So there is a direct relationship between GFR and (blank)
oxygen consumption
oxygen consumption
More blood flow into kidney, more work the kidney does and more (blank)
GFR
What process in the nephron requires the most energy?
Na reabsorption via Na/K atpase
Every time renal blood flow increase, (blank) increase
oxygen consumption
Sodium reabsorption is dependent on what?
Na/K ATPase
As sodium reabsorption goes up what do you consume more of?
oxygen!
So GFR and Na reabsorption are directly related to oxygen consumption
If you block the tubular sodium/potassium ATPase (oubain) activity will it increase or decrease oxygen consumption?
decrease (directly proportional remember)
If you block the tubular sodium/potassium ATPase activity will it increase or decrease oxygen consumption?
decrease ( directly proportional remember)
Why dont you want to give someone in heart failure prostaglandin inhibitors?
because it will not allow prostaglandins to produce to dialate arterioles to increase blood flow and instead you will cause contraction and reduce blood flow and make them die
