(02) - Renal Function

Question 1

The beginning of the explanation to this slide got cut off

he mentioned that collecting ducts also do some balancing as there are aquaporins (for water resorption) in there membranes (in the medulla) - even though they are mostly considered collecting vessels

actually i guess the previous stuff was referring to a question -

he talked about this for awhile then

mesangial area can expand and extract (control blood flow by changing size of capillaries) and also phagocytizes things

Answer 1

Question 2

filter (basically) = endothelial cell, basement membrance, podocytes (fluid that comes out goes between foot processes)

Answer 2

Question 3

(KEy Points)

1. Glomerulus is what part of the renal corpuscle?

2-4. Glomerulus contains what three things?

Answer 3

1. the capillary tuft
2. endothelium
3. mesangial area with cells (muscular/phagocytic function)
4. visceral epithelial cells (podocytes) with cell bodies and interdigitating foot processes

Question 4

pressure in capillary to move fluid out

filter function based on charge and size

endothelial slime layer lines inside of endothelium - don’t relaly understand its role so well

Answer 4

(cross section view)

foot processes connected to each other by a molecular layer calle the slit membrane (space between the two called the slit pore)

Question 5

this shows pretty much the same thing as previous

note that the glycosialoprotein coat on the foot processes are negatively charged (repel negatively charged moleclules) - easier for positively charged stuff

Answer 5

Question 6

in some disease processes the filtration barrier gets messed up

Answer 6

Question 7

Answer 7

D

Question 8

(Key Points)

1. All 3 layers of the glomerular capillary wall contribute to separation of blood/plasma from glomerular filtrate

2-3. What are the two principle sites of ultrafiltration?

Answer 8

2. the GBM (glomerular basement membrane)
3. slit processs of the podocytes

Question 9

this gives big picture of what goes on in the kidney

he talked for a spell about where and where not water could come in

also talked about where solute moved out

it’s passive all the way down the descending limb - passive going up on ascending limb until it beomes thick where it starts to actively pump salt out of the tubule

Answer 9

understand this

fine tuning is possible cause system isn’t overwhelmed by amount of fluid

Question 10

(Proximal Tubules)

(Proximal convoluted tubules)

1-4. What four features facilitate reabsorption?

Answer 10

1. apical intercellular tight junctions (when you pump it out it says out)
2. apical membrane brush border (microvilli) - increases surface area
3. basolateral intercellular interdigitations
4. prominent mitochondria associated with infoldings of basolateral membrane

(Na reabsorption is at the core of all of this)

Question 11

S1 - first convoluted segment

S2 - second convoluted

S3 - straight portion

1. which portion is most metabolicallary active?

Answer 11

1. first convoluted segment

Question 12

everything that goes on here is passive - don’t see alot of stuff

but once you get to TAL you see reemergance of mitochondria because it is actively pumping sodium out against its concentration gradient

Question 13

Answer 13

Question 14

distal tubule and collecting tubule are relatively active metabolically (not compared to proximal though)

regulate acid/base and Na and K - not big volumes though

in collecting ducts - only thing that really goes on is insertion of aquaporin which allows reabsorption of water

Question 15

(Key Points)

1. The tubules modify the vast volume of glomerular filtrate - keeping what is needed - eliminating what is not needed
2. Important substances are reabsorbed when and by what?
3. What generate the medullary concentrating gradient?

Answer 15

2. reabsorbed early in transit through metabolically active proximal tubules
3. Henle’s loop and Vasa recta

Question 16

(Key Points)

1. absorption of what occurs in loops of Henle?
2. What is reabsorbed in the ascending loops of Henle?
3. Where does assessment of excretory function occur?

Answer 16

1. water reabsorption
2. salt (impermable to water) - passive thin loops and active thick loops
3. where the TAL and glomerulus meet (macula densa and JG apparatus)

Question 17

(Key Points)

1. What occurs in the distal tubules?
2. What occurs in the collecting ducts? under influence of what?
3. Collecting tubules collect fluid from how many nephrons? Are they considered part of the kidney proper?

Answer 17

1. fine tuning of electrolytes
2. fine tuning of water; under influence of ADH (antiduretic hormone) - aquaporin
3. several; maybe not

Question 18

(Summary Medical Relevance)

1. Diseases that develop in selected portions of the kindeys may be anatomically localed on the basis of the function derangmenes that are recognize
2. protein-losing neuropathy - error where?
3. renal glucosuria (sugar in urine)
4. nephrogenic diabetes insipidus

Answer 18

2. leaking through glomerulus
3. proximal tubulue defect
4. kidney can’t reabsord water properly - collecting tubule problem - get very dilute urine - not getting enough ADH (anti-diuretic hormone)

Question 19

1. What is the primary function of the kidneys?

Answer 19

1. it regulates the composition of the extracellular fluid

(part of ECF is the intravascular fluid)

Question 20

(What is the primary function of the kidney?)

This is a dialysis machine (an artificial kidney) - modulates character of fluid - blood run against fluid with semi-oermeable membrane between - can regulate how much stuff moves across

kidney does more than just balance - also has hormonal components (for synth of RBC for example)

basically dialysis machine doesn’t cover everything the kidney does

Question 21

1-6. The kidney regulates what 6 things?

Answer 21

1. blood volume
2. extracellular fluid volume
3. systemic arterial blood pressure
4. hematocrit
5. acid-base balance
6. plasma conc of (electrolytes, minerals, metabolic waste, water)

Question 22

Have to be able to adjust to differing amounts of this stuff (food, water, salt)

Answer 22

Question 23

How Does keeping of balance work?

1. give the sequence

Answer 23

1. change in internal milieu –> sensors –> effectors (the kidneys)

(remember that input must equal output)

Question 24

Answer this…

Answer 24

B

Question 25

answer this…

Answer 25

B

Question 26

(regulation of volume)

1. add or subtract sodium
2. what will water do?

(Regulation of tonicity (sodium concentration))

3. add or subract what?

Answer 26

2. follow

(if you want to change water amount - change Na amount)

3. water

(the major osmotic substance in the ECF is sodium)

(intracellular based on K)

Question 27

answer this…

Answer 27

C