Lecture 20

Question 1

What is the role of kidneys?

Answer 1

Plasma volume (aka MAP)

Ion and water levels

Acid base balance

Pees drugs waste and hormones

Question 2

What is the endocrine function of kidneys?

Answer 2

Release renin - increase BP with angio 1/2

Erythropoietin - red blood cell production

Question 3

What occurs in the nephrons?

Answer 3

Afferent arterial supplies glomerulus with unfiltered blood (renal corpuscle) -> 20% of plasma is taken out by bulk flow and travels down proximal convoluted tubule where 62% is reabsorbed to efferent arteriole -> travels to descending loop of henle where water follows reabsorption of sodium -> ascending loop of henle absorbs more Na -> distal convoluted tubule

Question 4

What molecules are absorbed 100% in a healthy person?

Answer 4

Glucose

Amino acids

Lactate

Question 5

What are the components to the filtration membrane?

Answer 5

Fenestrated endothelium

Podocytes (strainer)

Fused basement membranes

Question 6

What is the filtrate composed of once passed the glomerular capsule?

Answer 6

Water
Glucose
Amino acids
Vitamins
Ions
Urea
Small small proteins

Question 7

What is the pH of filtrate?

Answer 7

7.45

Question 8

How much filtrated is processed in a day by both kidneys?

Answer 8

180 L in one day

Question 9

Does more blood get filtered if the MAP increases?

Answer 9

Yes. It relies on how much blood gets sent to the kidneys for the rate of filtration

Question 10

How is the filtrate intrinsically regulated?

Answer 10

Myogenic - high MAP = more stretch = afferent muscle contracts to stop high BP in glomerular caps

Juxtaglomerular - low BP = low filtration rate causes afferent arteriolars to dilate

Question 11

How is filtrate extrinsically regulated?

Answer 11

SNS - arteriole vasoconstriction

Extreme stress - lose fluids (sweat) and decreases filtration rate

Question 12

What can change the net filtration pressure?

Answer 12

Blood osmotic pressure - dehydration causes less filtration

Capsular pressure - obstruction (kidney stones) = less filtration

Question 13

Role of aldosterone?

Answer 13

High ADH - more water retention

Low ADH - inhibitory is released to encourage excess fluid to leave

Question 14

How is renin released?

Answer 14

Juxtaglomerula cells with granular cells sensing baroreceptors (MAP)

Na concentration from collecting ducts to tell granular cells by macula dense chemo receptors to release

SNS directly innervates renin release

Question 15

How can does renin stimulate the increase of blood volume?

Answer 15

Renin stimulates angiotensinogen in liver -> becomes angiotensin 1 -> lungs have angioconverting enzyme to make angio 1 to angio 2

Angio 2 increases blood volume in body

Question 16

How does angio 2 increase blood volume?

Answer 16

generalized vasoconstriction to increase BP

Constricts EFFERENT arteriole to increase GFR and high Na from the distal convoluted tubule

Release aldosterone from cortex to increase BP/ BV by absorb Na and water

Stimulates hypothalamus -> post.pituitary to release anti diuretic hormone and reabsorb water

Question 17

What are the 2 neuron types?

Answer 17

Juxtamedullar - deep in the medulla from more concentration/ diluted urine

Cortical - partially descends (primary one)

Question 18

Concentrated vs. Diluted urine

Answer 18

Concentrated - dehydration or low BP -> increased reabsorption in distal conduct tubule and collection duct OR aldosterone release to pull water in by Na and ADH release

Diluted - excess water or high BP -> less absorption in distal tubes and collection duct and ANP inhibits ADH. Allowing na and water out