Renal Basics

Question 1

The majority of sodium is reabsorbed in which segment of the nephron?

Answer 1

proximal convoluted tubule (50-55%), Na+/H+ exchangers, Na+ cotransporter (glucose/phosphate), Factors: Angiotensin II, Norepi, Reduced tubular flow.

Question 2

The major intracellular cation

Answer 2

Potassium

Question 3

The major extracellular cation

Answer 3

Sodium

Question 4

Names the parts of the nephron in order

Answer 4

Glomerulus (Afferent and efferent arterioles) , bowman’s Capsule, proximal convoluted tubule, Thin descending limb of loop of Henle, Thin ascending limb of loop of Henle, Thick ascending limb of loop of Henle, Distal convoluted tubule, cortical collecting tubule–> Medullary collecting tubule.

Question 5

The glomerular filtration barrier consists of what components?

Answer 5

glomerular endothelial cells, glomerular basement membrane, filtration slit diaphragm arising from glomerular epithelial cells (podocytes)

Question 6

The glomerular filtration barrier is based on selectivity

Answer 6

size and charge. Positive and small gets through

Question 7

What is the role of the kidney?

Answer 7

1) Clearance: excretion of waste products of metabolism, drugs and toxin
2) Homeostasis: sodium/volume, water/osmolality, electrolytes, acid-base
3) Hemodynamic and endocrine: renin, erythropoeitin, 1, 25- vitamin D

Question 8

What is the intracellular fluid volume of 70 kg patient

Answer 8

28 liters: Intracellular fluid is 40% of weight

Question 9

What is the total body water of 70 kg patient

Answer 9

42 liters: total body water is 60% of weight

Question 10

What is extracellular fluid volume of 70 kg patient

Answer 10

14 liters: extracellular fluid is 20% of weight

Question 11

What is the plasma volume of 70 kg patient

Answer 11

3.5 liters: plasma volume is 5 % of weight

Question 12

Extracellular fluid is divided into what two compartments

Answer 12

Plasma volume 5% of total weight and interstitial Space 15 %

Question 13

Electrolyte composition of intracellular compartment of body fluid

Answer 13

• major cation: K+

- major anions: proteins, phosphates, organic anions

Question 14

Electrolyte composition of extracellular compartment of body fluid

Answer 14

• major cations: Na+

- major anions: Cl-, HCO3-

Question 15

Balance what is in input, out and distribution

Answer 15

Input: Intake (enteric, IV) + production (catabolism generates H+).
Output: Excretion + consumption/destruction (metabolism + cellular growth)
Distribution: Intracellular/ extracellular shift and interstitial/ intravascular shift

Question 16

Sodium homeostasis key point

Answer 16

water follows sodium: changes in sodium homeostasis results in changes in body fluid volume not sodium concentration

Question 17

An increase of sodium intake will generally result in

Answer 17

net gain in bdy fluid (solute + water). ingestion/retention of proportional amount of water to maintain serum sodium concentration unchanged

Question 18

Sodium mode of reabsorption in loop of henle

Answer 18

35-40% Na+/K/2CL- co transporter. Flow dependent

Question 19

Sodium mode of reabsorption in distal tubule

Answer 19

5-8% Na+/Cl- co-transport, flow-dependent

Question 20

Sodium mode of reabsorption in collecting Tubule

Answer 20

2-3% Na+ Channels. Aldosterone, down-regulated by ANP

Question 21

Sodium is taken out by

Answer 21

NA/K+-ATPase 3 NA (out cell) and 2 K (in cell)

Question 22

Renin stimulated how (kidney endocrine function)

Answer 22

when reduced distal tubular flow indicated by fall in tubular Cl-, B-adrenergic sympathetic activity

Question 23

Renin effects

Answer 23

renin–> activated liver to Release angiotensinogen-> Angiotensin I (ACE from lungs convert it to ) Angiotensin II–> increase vascular tone (Ang II) and activates adrenal to release aldosterone, thus reduce Urine sodium. angII act in proximal and aldosterone in distal tubule

Question 24

Role of kidney in Erythropoeitin

Answer 24

stimulate erythroid progenitor in bone marrow to differentiate in RBC.

Question 25

Role of kidney in calcitriol (active vitamin D)

Answer 25

Activates vitamin D in response to hypocalcemia and hypophosphatemia.

parathyroid/ PTH–>kidney and bones. In kidney changes calcidiol to active form in calcitriol

Calcitrol increase small intestine reabsorption of calcium and mobilization of bone –> increase serum calcium

Question 26

Clearance of waste is achieve by

Answer 26

generation of large volume of glomerular filtrate, of which almost all electrolytes and water are reabsorbed, leaving urine concentration in waste products (urea, creatinine)

Question 27

Homeostasis is achieve by kidney by

Answer 27

selective reabsorption and secretion by the tubules of key substance such as sodium, water, potassium, bicarbonate/H+, calicum