Nephro Physiology

Question 1

anatomy of nephron in order

Answer 1

proximal tubule
loop of henle with capillary network (down thin descending, up thick ascending)
distal tubule
collecting duct

Question 2

start of filtration of nephron

Answer 2

glomerulus surrounded by bowmans capsule

Question 3

early/proximal convoluted tubule (PCT)

Answer 3

• brush border that reabsorbs ALL glucose and AA (from urine > lumen > blood)
• reabsorbs most bicarb, sodium, chloride, potassium, water, uric acid, and phosphorus

parathyroid hormone - inhibits sodium/phosphorus cotransport (reabsorption)

Question 4

what enzyme is used in PCT resorption processes

Answer 4

carbonic anhydrase

Question 5

thin descending loop of henle

Answer 5

-passive reabsorption of water
-impermeable to sodium
-makes urine hypertonic (concentrated)

Question 6

functions of parts of the nephron

Answer 6

• renal corpuscle: filtration
• PCT: reabsorption, secretion (vital)
• Loop of henle: solution concentration
• DCT: reabsorption, secretion (optional)
• collecting duct: (optional)

Question 7

where is the only area of the nephron that cannot reabsorb sodium?

Answer 7

thin descending loop of henle

Question 8

thick ascending loop of henle

Answer 8

• reabsorbs smaller amounts of sodium, potassium, and chloride (requires ATP)
• indirectly absorbs magnesium/calcium paracellularly (bw cells) via gradient generated by potassium backleak
• impermeable to water
• urine less concentrated

Question 9

distal convoluted tubule

Answer 9

-reabsorbs even less sodium
-reabsorbs chloride
-impermeable to water
-makes urine fully dilute (hypotonic)

PTH inc ca reabsorption via ca/na exchange

Question 10

collecting duct

Answer 10

• reabsorbs small amounts of sodium in exchange for potassium/hydrogen (regulated by aldosterone)

ADH inserts more aquaporin water channels on apical side of membrane (urine side) and inc urea reabsorption

Question 11

what section of the nephron is trying to absorb everything?

Answer 11

PCT

only gets rid of Hydrogen

Question 12

concerning the RAA system, what do the kidneys produce vs the liver?

Answer 12

liver: angiotensinogen
kidneys: renin

Question 13

what converts angiotensinogen to angiotensin I?

Answer 13

renin from the kidney

Question 14

what converts angiotensin I to angiotensin II

Answer 14

ACE from the surface of the pulmonary and renal epithelium

Question 15

what stimulates the kidneys to produce renin?

Answer 15

decrease in renal perfusion (JGA)

Question 16

what are the effects of angiotensin II?

Answer 16

-inc symp activity
-stim tubular na/cl reabsorption, k excretion, h2o retention
-arteriolar vasoconstriction, inc BP
-stim ADH secretion via post pituitary
- stim h20 reabsorption in collecting duct
- inc aldosterone secretion via adrenal cortex (inc BV via inc na and h20)

overall water and salt retention, effective circulating volume inc. perfusion of JGA inc.

Question 17

RAA system regulation

Answer 17

neg feedback via JGA pressure measurements

Question 18

renin secretion and effects

Answer 18

• secreted by JG cells
• inc secretion due to dec renal perfusion pressure (low blood vol, detected by afferent arteriole)
• inc renal sympathetic d/t (B1 effect)
• dec NaCl delivery to macula densa cells (bc its reabsorbing it back into the blood)

Question 19

what things could be triggers for the RAA system?

Answer 19

dehydration
Na def
hemorrhage
high EC pot (affects at aldosterone stage, not full sys)

Question 20

ACE secretion and effects

Answer 20

• catalyzes conversion of angiotensin I > II
• located in multiple tissues
• conversion occurs the most in the lung
• provided by vascular endothelial cells in the lung

Question 21

angiotension II functions

Answer 21

• maintains BP and volume
• affects baroreceptors
• limits reflex bradycardia (HR dropping with blood vol change)

Question 22

atrial/brain natriuretic peptide (ANP/BNP) secretion and functions

Answer 22

• released from atria and ventricles
• released due to inc volume to inhibit RAA system
• relaxes vascular smooth muscle via cGMP > inc GFR, dec renin
• dilates afferent arteriole

Question 23

ADH/vasopressin effect on nephro sys

Answer 23

• regulates serum osmlolality
• responds to low blood vol states
• stim reabsorption of water in collecting ducts
• stim reabsorption of urea in collecting ducts

Question 24

aldosterone effect on nephro

Answer 24

• reg EC fluid vol and sodium content
• inc release in hypovolemic states
• inc potassim excretion in response to hyperkalemia (exchanging it for sodium)

Question 25

respiratory acidosis definition

Answer 25

- arterial pH <7.35 (acidemia) - high carbon dioxide

Question 27

respiratory acidosis causes

Answer 27

caused by hypoventilation, - airway obstruction - acute/chronic lung dz - dec respiratory stimuli (anestheisa, opiods, sedatives) - weakening of respiratory muscles

Question 28

respiratory acidosis sx

Answer 28

hypoventilation > hypoxia - rapid, shallow respirations - dec BP with vasodilation - dyspnea - headache - hyperkalemia - dysrhythmias (from inc K) - drowsiness, weakness, disorientation - muscle weakness, hyperreflexia

Question 29

metabolic acidosis

Answer 29

arterial pH < 7.35 low bicarb OR inc acids (INC anion gap)

Question 30

causes of metabolic acidosis with INC anion gap

Answer 30

INC anion gap (sodium-chloride+bicarb) GOLDMARK - glycols - oxoproline (chronic acetominophen use) - L lactate - methanol - aspirin - renal failure (carbonic anhydrase inhibitor, RTA) - ketones (DKA, starvation)

Question 31

causes of metabolic acidosis with NORMAL anion gap

Answer 31

HARDASS - hyperchloremia - addison dz (low cortisol) - renal tubular acidosis - diarrhea - acetazolamide - spironolactone - saline infusion

Question 32

metabolic acidosis sx

Answer 32

- headache - dec BP - hyperkalemia - muscle twitching - warm, flushed skin (vasodilation) - N/V - dec muscle tone and reflexes - kussmall respirations (compensatory hyperventilation)

Question 33

causes of metabolic acidosis

Answer 33

inc H production - DKA, hypermetabolism dec H elimination - renal failure dec HCO3 production - dehydration, liver failure inc HCO3 elimination - diarrhea, fistulas

Question 34

respiratory alklaosis causes

Answer 34

pH > 7.35 low CO2; hyperventilation - anxiety - hypoxemia - salicylates - tumor - PE - pregnancy

Question 35

respiratory alkalosis sx

Answer 35

- hyperventilation (inc rate + depth) - tachycardia - dec or normal BP - hypokalemia - numbness/tingling extremities - hyper reflexes, muscle cramping - seizures - inc anxiety, irritability

Question 36

metabolic alkalosis causes

Answer 36

pH > 7.35 high bicarb check urine chloride high chloride (saline resistant) - hyperaldosteronism - bartter syndrome - gitelman syndrome low chloride (saline responsive) - vomiting - recent loop/thiazide diuretics - antacids

Question 37

metabolic alkalosis sx

Answer 37

- restlessness > lethargy - dysrhytmias, tachycardia - compensatory hypoventilation - confusion (LOC, dizzy, irritable) - N/V, diarrhea - tremors, muscle cramps, tingling of fingers/toes - hypokalemia