Final Flashcards
Major functions of the circulatory System (3)
- Transport nutrients to tissues
- transporting waste products away form tissues
- transporting hormones: signaling
Physical characteristics of circulatory system (4)
- Volume (Ex liter)
- Velocity
- Pressure (mmHg)
- Area (size)
Blood flow determinants (5)
- Blood flow (ml/min)
- Vascular resistance
- blood pressures
- Vascular conductance
- Poiseulle’s law
High resistance causes ______ blood flow
poor
vascular resistance determines how much _______ we have
blood pressure
Pressure above a “choke point” is typically _______ and it is ______ below
higher
lower
inverse of vascular resistance
vascular conductance
what is conductance
How easy is it to drive flow through a conduit (blood vessel)
Vast majority of our blood is stored in our? what %?
veins
84%
The kidney controls how much _____ we have in our body? How is this related to blood volume?
fluid; if we reabsorb more fluid, this can increase our blood volume a little bit
What percent of our blood volume is in the heart?
7%
What is a system in series? How does this affect resistance?
Adding vessels end to end to find combined resistance;
increases resistance
what is system in parallel? How does this affect resistance?
Multiple pathways the blood can choose to flow through; decreases resistance
How is the circulatory system arranged? which system? What about the kidney?
BOTH
1. System in series
2. System in parallel
How to calculate system in series
R total = R1 + R2 + R3….
What is the cross sectional area of the aorta?
2.5 cm^2 OR
4.5 cm^2
What is the cross sectional area of the small arteries?
20 cm^2
What is the cross sectional area of the capillaries?
2500 cm^2 OR
4500 cm^2
What is the cross sectional area of the venae cavae
8 cm^2 OR
18 cm^2
Velocity of blood flow =
blood flow/cross sectional area
Phenylephrine works on the
small arteries and arterioles
Resistance vessels that determine blood pressure
small arteries and arterioles
How does kidney manage blood flow?
adjusting vascular resistance
Blood flow for tissue depends on
metabolic rate
What is Laminar flow? Describe the flow near the walls of the vessel.
Ideal efficient flow where blood is pushed forwards and orderly; the walls create resistance, therefore flow is reduced closest to the walls
what is turbulent flow?
inefficient movement of blood where it is not moving straight forward but in different directions
What happens to vessels with turbulent flow? What causes turbulent flow?
remodeling;
Clot or blockage leading to a narrow opening for blood to go through
How much cardiac output do kidneys receive?
1 L/ min
20 %
What is different about the kidneys in regards to how much they are perfused? (2)
They get more blood flow than they need in order to filter appropriately; they are only PARTIALLY controlled by the metabolic demands of the tissue
What are two blood flow determinants? (2 laws)
- Ohm’s Law (V=IR)
- Poiseulle’s law
Ohm’s Law rearranged
change in pressure = Flow x vascular resistance
A small change in blood vessel diameter has what effect? (Poiseulle’s law)
Very big difference in blood pressure
Conductance =
1/ Resistance
What are the long term roles of the kidney? (7)
- BP
- pH
- RBC
- electrolytes
- Vit D
- serum glucose
- metabolic waste disposal
If there is an issue with chronic BP, it is an indication that
There is an issue with the kidneys
uncontrolled diabetes can lead to increased _______
Nitrogen compounds (urea)
If the body is hypernatremic, how will the kidneys respond? Using what receptors?
- Get rid of excess sodium or reabsorb more water
- decrease ADH
Most kidney management is done via
autoregulation of GFR
Largest artery feeding into the kidney
Renal artery
Renal arteries split into
Segmental arteries
segmental arteries split into
interlobar arteries
Interlobar arteries split into
Artuate arteries
Arcuate arteries split into
interlobular arteries
What sits behind the afferent arteriole?
Glomerular capillaries
Bulk of reabsorption occurs at
Peritubular capillaries
List veins in order from smallest to largest
- Interlobular
- Arcuate veins
- Interlobar
- Segmental
- Renal
What are the vessels in the nephrons? (4)
- Afferent arterioles
- glomerular capillaries
- efferent arterioles
- peritubular capillaries
How many nephrons does a person under 40 have?
2 million
What are the two parts of nephrons
- Superficial (cortex)
- Deep (intermedulla)
What percent of our nephron are more cortical?
90%
What percent of our nephron are medullary?
5-10%
Where is the peritubular capillary network?
majority in outer medulla
Are there more ascending or descending blood vessels in our inner medulla? Why?
ascending
There are split points to decrease the velocity to maintain a normal level of solutes in the renal interstitium
What would happen if there is increased rate of flow in the ascending vasa recta?
The renal interstitium will get washed out. Reabsorption will be affected
What are the ascending/ descending peritubular capillaries called?
Vasa recta
T/F: The medullary capillaries are the least sensitive to changes in blood pressure
False; very sensitive to low BP or inadequate perfusion
Where are the kidneys housed
right underneath the diaphragm
Where does the renal vein sit?
under the mesenteric arteries
What sits on top of the kidneys
Adrenal glands
What are ureters?
collection system of whatever is left in the tubules
The top of the right kidney comes into contact with the
liver
Top of left kidney comes into contact with the ______. Whats it called?
stomach
Gastric surface
Identify the gastric surface, splenic surface, pancreatic surface, and descending colic surface
Identify the hepatic surface and right colic flexure surface
T/F: The pancreas comes into contact with the left kidney
True
What comes together to form the ureter?
Minor and major calyx
Gland that surrounds the urethra in males
prostate
What system controls emptying of the bladder? Which nerve? What spinal nerves does it come off?
PNS and SNS
Pudendeal
S 2,3,4
The spinal nerves 2,3,4 are in charge of
Solid and urinary waste
Where does the pudendeal nerve run next to? besides continence what is it in charge of?
Prostate gland
Erection
What does the macula densa do
monitor filtration rate
(how much fluid is being filtered)
Where is the macula densa located
Thick ascending loop of Henle
The _____ collecting duct empties into the papillary duct
Medullary
The flow through the macula densa is measured by
juxtaglomerular cells
When is renin released? This will cause ?
When juxtaglomerular cells sense a decrease in BP
Increase Angiotensin II
Vasoconstriction of EA
Renal clearance describes
Quantity of plasma (ml) that is cleared of a substance per unit of time (min)
What are the units for renal clearance?
mL/min
Urinary flow rate
1ml/min
Excretion rate
volume x
Exogenous substance that is given as the gold standard to measure GFR
inulin
If inulin is the gold standard, why is it not used more often?
It requires more measurements, its difficult to do, and is more expensive
Where does most reabsorption take place?
Proximal convoluted tubule
T/F: All segments of the nephron reabsorb something
true
What portion of water is reabsorbed in the PCT?
water
T/F: creatitine is diluted more and more as we go along the nephron
false
What does the macula densa measure in regards to Na
How many Na pass per unit time
If we have a higher than normal filtration rate with a normal reabsorption rate, how will that affect the amount of Na and Cl near the macula densa?
Increased amount of Na and Cl; high GFR
How does the body respond to low GFR?
increase angiotensin II, constrict AA, reabsorb more Na at PCT
Increased reabsorption of Na at the PCT will cause a _________ at the macula densa. Is this considered a true low GFR? What is the effect?
deficit
No, GFR and BP are normal;
increased GFR
What causes PCT to increase Na absorption?
Elevated glucose levels, elevated amino acids
What is normally reabsorbed at the PCT?
Glucose and amino acids
T/F: Most glucose is reabsorbed at the PCT under normal conditions
False; all of it
for every glucose molecule, ______ Na molecules must be reabsorbed. What pump is utilized?
1; SGLT
What is the primary cause of degradation of the kidneys with uncontrolled DM?
hyperfiltration
Side of the tubular cell walls next to the lumen
Apical
Side of the tubular cell walls next to the interstitial fluid
Basolateral
What is the level of glucose at the end of the PCT?
practically Zero
How does glucose leave the tubular cells to through the basolateral side? Does it require energy?
Glut transporter
No
What are the 3 part of the PCT?
S1, S2, S3
What segment is responsible for the most glucose reabsorption? What percent? What transporters are there?
S1
90%
SGLT-2 AND Glut-2
T/F: Glut-2 transporters have a low affinity for glucose
True
What glucose transporters are at the S2 segment? Do they have a high or low affinity for glucose?
SGLT-1 and GLUT1
high
T/F: There are no SGLT transporters in the S3 segment of the PCT
False; just a few
What is the normal amount of glucose reabsorbed at the PCT
about 125 mg/min
What is a normal blood glucose
100 mg/dl
What is filtered load?
The amount of whatever is being dissolved in the fluid being filtered
At what point will we expect to see glucose in the urine? what is this point called?
200 mg/dL
threshold
What does the transport maximum refer to? What level of glucose is that?
The point where there is a 1:1 relationship between filtered load and glucose excreted (no more glucose can be transported) ; 300 mg/DL
How much glucose is being reabsorbed once we hit transport maximum?
none
What ions are the macula densa sensitive to? Which is primary?
Na* and Cl
Where is angiotensinogen produced? What does it convert to and how?
liver;
angiotensin I via renin
Angiotensin I is converted to _______ by ________
Angtiotensin II
ACE
Dilation to the afferent arteriole will cause what effect to the glomerular capillaries?
Increased renal blood flow
An increase is efferent arteriolar resistance will cause what effect to glomerular capillaries?
increased renal blood flow
T/F: Angiotensin II only contracts the efferent arteriole
False; both. Efferent is primary
Medications that relax blood vessels primarily work at the _______ arteriole
afferent
What are AT1 receptors and where are they located?
angiotensin receptors
PCT
What effect does increasing activity of the NaK atpase pump have on sodium?
increase the amount of Na leaving the tubular cells, decreasing the amount of Na inside the cell, increasing the concentration gradient for the NHE transporter, moving more sodium from the tubular lumen into the cells
How does bicarb leave the tubular cells?
Na bicarb co transporter
Angiotensin II ________ the NaK atpase
speeds up
pathway between the cells
paracellular pathway
“tight junctions”
What ions goes through the paracellular route of PCT?
Cl, Ca
What does transcellular reabsorption refer to?
movement through the cell wall usually by transporter
Water moves transcellularly through
aquaporin channels
Any water thats reabsorbed is does so how?
osmosis; follows ions
Are there any water pumps in the kidneys to reabsorb water from the tubules?
no
What does the body utilize to reabsorb water?
urea
The luminal side of the the PCT looks like? why?
brush border
to increase surface area for transporters
T/F: tubular epithelial cells have a membrane potential
true; -70 mV
What is the charge associated with the tubular lumen of the PCT? this is due to what?
- 3 mV
net charge of ions
T/F: sodium gets concentrated in the PCT
false; chloride does a little bit
Where can we find carbonic anhydrase and its function
PCT;
acid base management
Primary reabsorption process for Na
Na K atpase
How does the PCT regulate bicarb?
HCO3 combines with protons pumped into the tubule from the Na H pump to form carbonic acid (H2CO3). Carbonic anhydrase helps it disassociate to CO2 and H2O which can be reabsorbed into the tubular cells.
once inside the tubular cells, carbonic anhydrase helps combine CO2 and H2O to form carbonic acid which then disassociates back into bicarb and protons. Bicarb can then leave the tubular cells and be reabsorbed
Where is carbonic anhydrase stored?
Some are tethered to cell wall, some is inside the cell wall, and some is wedged in the cell wall
Biggest issue with carbonic anhydrase inhibitors
acidoses
Where is glutamine produced
liver
Glutamine can be broken down into
- 2 molecules bicarb
- 2 molecules ammonium
Important Urinary buffers (2)
ammonium, phosphates
Where is Ca reabsorbed in the tubule?
PCT- paracellularly and transcellularly
How does calcium enter the PCT transcellularly? Leave the PCT ?
- Ca pumps
- Ca ATPase pump and NCX