overview of renal physiology

Question 1

Hypovolemia

Answer 1

A deficit in intravascular volume

Question 2

Signs of hypovolemia

Answer 2

• signs of low effective circulating volume

- it activates all mechanism that go along with low ECF including renin, angiotensin

Question 3

Dehydration

Answer 3

• state of intracellular volume loss

- can only be seen in setting of hypernatremia (this is what pulls volume out of the cells)

Question 4

Things your kidneys do for you

Answer 4

1. Clean blood of toxins
2. Balance electrolytes
3. Balance water intake/losses
4. Produce or modify hormones
   - Vitamin D
   - Erythropoietin
5. Calcium/phosphate/PTH
   - bone health
6. Acid base balance
7. Manage blood pressure
8. Growth
9. Psychosocial/developmental

Question 5

Areas of the nephron

Answer 5

1. Renal corpuscle
2. Proximal convoluted tubule
3. Loop of Henle
4. Distal convoluted tubule
5. Collecting duct
6. Papillary duct

Question 6

Renal corpuscle function

Answer 6

Production of filtrate

composed of bowmans capsule + glomerulus?

Question 7

Proximal convoluted tubule function

Answer 7

Reabsorption of water, ions, and all organic nutrients

Question 8

Loop of henle function

Answer 8

Further reabsorption of water (descending limb) and both sodium and chloride ions (ascending limb)

Question 9

Distal convoluted tubule function

Answer 9

Secretion of ions, acids, drugs, toxins

Variable reabsorption of water, sodium ions and calcium ions (under hormonal control)

Question 10

Collecting duct function

Answer 10

Variable reabsorption of water and reabsorption or secretion of sodium, potassium, hydrogen, and bicarbonate ions

Question 11

Papilary duct function

Answer 11

Delivery of urine to minor calyx

Question 12

4 compartments of the kidney

Answer 12

1) Vascular
2) Interstitial
3) Glomerular
4) Tubular

Question 13

How any liters does kidney filter per day in adult male

Answer 13

Approx 180 L per day in adult male

Question 14

Global assessment of renal clearance

Answer 14

-usually measured by glomerular filtration rate

Question 15

Average glomerular filtration rate

Answer 15

90-120 ml/min

Question 16

How does kidney balance electrolytes

Answer 16

• via transporter systems throughout tubule (both energy requiring and passive)
• can absorb and secrete various substances to maintain homeostasis

Question 17

Effect of damage to one segment of tubule

Answer 17

-may lead to compensatory function of another segment

Question 18

Prime directive for Kidney

Answer 18

Preserve vascular function –> via salt preservation (99% + of salt in reabsorbed)

Question 19

How much urine is produced per day

Answer 19

0.5- 10 L per day

Question 20

Factors that control water balance

Answer 20

• osmotic load
• renin/angiotensin
• antidiuretic hormone
• renal blood flow
• renal concentration gradient

Question 21

How kidney produces/modifies hormones

Answer 21

1) activates vitamin D by 1-alpha-hydroxylation of 25-vit D from the liver to make 1, 25-Vit D
2) Produces erythropoietin from interstitial cells which assists in production of RBCs

Question 22

How kidneys contribute to bone health (3)

Answer 22

1) production of 1, 25 Vit D
2) control of Calcium and phosphate reabsorption/loss
3) respond to variety of external stimuli such as PTH or Acidosis in ways that can affect bone

Question 23

How kidneys contribute to acid/base handling

Answer 23

1) Reclaim HCO3 that is filtered (proximal tubule)

2) Regenerate the lost buffering capacity to allow on-going acid production (distal tubule)

Question 24

What complex interactions are involved in blood pressure

Answer 24

1) Salt and water balance
2) Sympathetic nervous system
3) Hormonal effects
- angiotensin, renin, aldosterone

Question 25

How kidney is involved in growth (3)

Answer 25

• chronic acidosis
• inability to clear IGF-BPs
• bony abnormalities

Question 26

How kidney is involved in Psychosocial /development

Answer 26

• uremia clouds the min
• significant developmental delay in infants not dialyzed well enough
• math and abstraction reasoning affected disproportionately
• effects on QoL, anger, management, forgetfullness