Lesson 28: Topic 24 - Intro to Renal Physiology Flashcards
what is the main functional unit of the kidney?
the nephron
what is the kidney attached to?
the ureter
where do we produce urine from?
the ureter, from the kidney undergoing filtration and then exits the renal pelvis and then dumps the urine into the ureter
where do we have the renal medulla?
in the renal pyramid
where is the nephron?
in the renal medulla
where does filtration - reabsorption of the kidney happen?
in the nephron
what is the outer layer of the kidney?
the renal cortex
what is on the deeper level of the renal cortex?
the renal medulla
what are the five functions of the kidney?
- maintain fluid and ion homeostasis
- waste excretion
- drug removal
- hormone production
- glucose synthesis
how does the kidney maintain fluid and ion homeostasis?
by:
- regulating extracellular volume and blood pressure
- osmolarity ; controlling how many solutes are being absorbed back into your blood or how much can be excreted
- ion balance
- pH (by filtering H+ ions)
what hormones does the kidney produce?
- epo - erythropoietin - important for the production of red blood cells
- vitamin D activation
- renin –> angiotensin 2
what is the total body fluid volume?
40L
how much of our body fluid volume is blood?
5L out of the 40
of our 5L of blood in our body, how much is plasma?
3L of the 5L (60%)
what is our cardiac output per day?
7200L/Day
how much of our cardiac output is given to the kidneys?
20% (about 1500L/day)
what part of the blood does the kidney filter?
the plasma
if our kidneys has 1500L per day of cardiac output, how much of that is plasma
60% of 1500 = 900L/day of plasma is going to flow in the renal system
how much renal plasma flow is filtered by the glomerulus per day?
GFR = 180L/day (900 x 20%)
- only 20% of plasma is filtered
- GFR means glomerular filtration rate
what percent of our fluid is lost as urine per day?
1%
our cardiac output is about 5L/min, 20% enters the kidney. how much /min enters the kidney? how much of that is plasma?
about 1.041L total blood/min. 60% is plasma = 625ml plasma/min
the glomerulus only filters 20% of the blood that enters the kidney, so how much is it filtering?
1.041L blood/min –> 625 ml plasma/min
20% of 625 = 125ml/min the glomerulus filters
the 1.041L of blood enters the kidney how?
via the afferent arteiole
the 80% of blood that did not get filtered (bypasses) by the glomerulus in the kidney exits the kidney how?
via the efferent arteriole and then goes down into the peritubular capillary and then goes back into the venous system
what is a glomerulus?
it is a capillary in order to filtrate
after the plasma is filtered by the glomerulus, where does it immediately go?
into the Bowmans capsule
what is the beginning of the kidney tubule system?
the Bowman’s capsule
of the 20% (125mL) that enters into the kidney tubule, what percentage is reabsorbed by the peritubular capillary?
99% (120mL)
- the 1% is excreted as urine (5mL)
adding the reabsorbed plasma with the plasma that was not filtered, how much plasma/min is in the venous system?
620mL/min of the 625mL (the 5mL is excreted)
when secretion happens, it is a very small amount. in what direction does it happen? (in the kidney)
from the peritubular capillary to the kidney tubule
if cardiac output is 4L/min in a healthy child, how much plasma would be filtered by the kidneys in ml/min
4000mL/min x 20% of CO to the kidneys = 800mL
800mL x 60% is plasma = 480mL
480mL x 20% of plasma is filtered by glomerulus = 96 ml/min
= 96 ml/min
what is the functional unit of the kidney?
the nephron
what encompasses and surrounds all of the tubule system?
the peritubular capillaries
where does the peritubular capillaries drain into?
the venules then to the veins
what is the tubule system immediately after the Bowman’s capsule called?
the proximal tubule
the proximal tubule turns into?
the descending loop of henle
the descending loop of henle turns into?
the ascending loop of henle
the ascending loop of henle turns into?
the distal tubule
what does the distal tubule dump into?
the collecting duct which then excretes urine
what is apart of the renal corpuscle?
- glomerulus and Bowman’s capsule
what is apart of the tubule system?
- proximal tubule
- descending/ascending loop of henle
- distal tubule
- collecting duct
what branches off of the collecting duct?
nephrons
- many nephrons dump waste into the collecting duct
what is the pathway of filtration through nephrons?
glomerulus –> bowman’s space –> proximal convoluted tubule –> proximal straight tubule –> D thin Loop –> A thin Loop –> A thick Loop –> distal convoluted tubule –> cortical collecting duct –> medullary collecting duct –> renal pelvis
which part of the collecting duct is the medullary duct?
the deeper, bottom section
what is the pathway for the 80% of the plasma that bypasses the filtration?
renal artery –> afferent arteriole –> glomerulus –> efferent arteriole –> peritubular capillaries or Vasa Recta –> venues –> renal vein
what is the vasa recta?
continuation of the efferent arteriole
what are the two types of nephrons?
- cortical
- juxtamedullary
**
the renal corpuscle of ALL nephrons is where?
in the cortex region of the kidney
where is the glomeruli in the juxtamedullary nephrons?
in the inner layer of cortex, closer to the medulla
what % of nephrons are the juxtamedullary nephrons?
20%
what is the size of the Henle’s loop in the juxtamedullary nephrons?
Long Henle’s loop
true or false: the juxtamedullary nephrons produce concentrated urine?
true
- due to the vasa recta because it is deep in the medulla
the vasa recta is a unique structure to which nephron?
the juxtamedullary nephrons
the glomerulus of the cortical nephrons sits where?
on the outer layer of the renal cortex
what percentage of nephrons is cortical nephrons?
80%
which nephron plays a role in respiratory and regulatory functions including water absorption. solute absorption and ion absorption?
the cortical nephrons
true or false: vasa recta is a continuation of the efferent arteriole in the juxtamedullary nephrons
true
true or false: blood from the afferent arteriole flows next into the peritubular capillary
false
true or false: plasma enters the loop of henle from the distal tubule
false
what are the three critical functions of the nephron?
- glomerular filtration
- tubular reabsorption
- tubular secretion
what is glomerular filtration?
nondiscriminant filtration of a protein-free plasma from the glomerulus into the Bowman’s capsule (some proteins will not filter - like albumin)
what is tubular reabsorption?
selective movement of filtered substances from the tubular lumen into the peritubular capillaries
what is tubular secretion?
selective movement of nonfiltered substances from the peritubular capillaries into the tubular lumen
what is the equation to figure out the amount of solute excreted?
amount filtered - amount reabsorbed + amount secreted
can RBC, WBC or plasma proteins enter through into the glomerulus?
no. only plasma, water, ions and small molecules
- they cannot fit through the filtration barrier (it has a certain size) therefore are just sent to venous system (good, this is why we do not urinate blood)
the plasma that enters into the glomerulus is referred to as?
filtrate
what are the structures of the glomerulus?
- endothelial cells
- basement membrane
- lumen
the tubule and bowman’s capsule is composed of?
epithelial cells (does not allow for good filtration - we want this, this is good)
the glomerulus is made up of?
podocytes, which are separated by filtration slits which is where the filtration happens
the movement of filtrated is through?
the pores between the endothelial cells, then passes through the basement membrane where it allows for endothelial cells to attach to, and then exits through the podocyte filtration slits
the pores between the endothelial cells can be called?
fenestrations ( a pore, a window, an opening )
