Renal

Question 1

Components of renal fxn

Answer 1

• Glomerular filtration
• Tubular secretion
• Tubular reabsorption
• Excretion

Question 2

Renal corpuscle

Answer 2

• Where ultrafiltrate originates

- Glomerulus & Bowman’s capsule

Question 3

Renal pelvis

Answer 3

Where ultrafiltrate leaves kidney

Question 4

Renal vasculature

Answer 4

Renal artery –> interlobar a –> arcuate a –> interlobular a –> afferent arteriole –> glomerular capillary –> efferent arteriole –> peritubular capillary

Question 5

What are the 3 capillary beds?

Answer 5

• Glomerular: filtration
• Peritubular: reabsorption, secretion
• Vasa recta - specialized peritubular: Osmotic exchangers

Question 6

Renal blood flow (RBF)

Answer 6

Total volume of blood delivered to kidneys per unit time = 1.25

Question 7

Renal plasma flow (RPF)

Answer 7

• Volume of plasma delivered to kidneys per unit time

Question 8

How much of plasma is filtered?

Answer 8

20%

- Becomes ultrafiltrate in Bowman’s

Question 9

Glomerular filtration

Answer 9

1. Forming urine

2. RBF enters glomerular capillaries & portion of blood is filtered into 1st part of the nephron

Question 10

Corpuscle

Answer 10

A glomerulus & Bowman’s capsule

Question 11

Filtration barriers consist of what 3 layers?

Answer 11

• Capillary endothelium
• Basement membrane
• Capsular epithelial cells

Question 12

What is the most significant layer of the filtration barriers?

Answer 12

Basement membrane

- Barrier to plasma proteins

Question 13

Sympathetic nn

Answer 13

• Vasoconstriction by binding to alpha1 receptors on afferent arteriole
• Response to hemorrhage
• Decrease RBF

Question 14

Angll

Answer 14

• Vasoconstriction of both afferent & efferent arterioles, but efferent is more sensitive
• Decrease RBP

Question 15

How can RPF & GFR be controlled?

Answer 15

By controlling resistance of the afferent arteriole

Question 16

Prostaglandins (PGE2, PGI2)

Answer 16

• Vasodilate
• Protective effect
• Increase RBF

Question 17

Dopamine

Answer 17

• Vasodilate via dopamine receptors (D1, D3, D5)
• Protective effect; admin in shock
• Increase RBF

Question 18

Other vasodilators

Answer 18

• ANP

- NO

Question 19

Changes in GFR can be brought about by changes in what?

Answer 19

Starling forces

Question 20

What does GFR depend on?

Answer 20

The sum of starling forces

- Forces favoring vs. forces opposing

Question 21

Reabsorption

Answer 21

Returns substances to circulation

Question 22

Secretory

Answer 22

Remove substances from blood & add to urine

Question 23

What is the most important fxn of the kidney?

Answer 23

Reabsorption of sodium

Question 24

Descending thin limb

Answer 24

• Passive permeability to H2O, NaCl & urea

Question 25

Ascending thick limb

Answer 25

- Active NaCl reabsorption - Load dependent - Impermeable to H2O

Question 26

Principal cells (late DT & CD)

Answer 26

- Aldosterone & ANF sensitive sodium reabsorption - Also reabsorbs H2O & secretes K+ - Driving force established by Na-K- ATPase in basolateral membrane

Question 27

ADH

Answer 27

Reabsorbs H2O & NaCl

Question 28

Role of ADH

Answer 28

- Binds V2 receptors in basolateral membrane - Stimulates Gs (activates adenylate cyclase, increases cAMP) - Activates protein kinase A - Phosphorylates intracellular structures - H2O channels shuttled to apical membrane - Inserted into membrane --> H2O reabsorption

Question 29

Hypoosmolarity

Answer 29

Excess H2O in body | - Kidneys excrete urine w/ low osmolarity (H2O diuresis)

Question 30

Hyperosmolarity

Answer 30

Deficit of H2O | - Kidneys concentrate urine (Antidiuresis)

Question 31

Normal urine

Answer 31

Slightly hypertonic

Question 32

Control of BP

Answer 32

- Baroreceptor reflex (neurally-mediated, reacts in secs) | - Renin-angiotensin aldosterone (hormonally-mediated, reacts in mins to hrs)

Question 33

What determines volume?

Answer 33

Amount of Na+ in ECF

Question 34

What is the single most important controller of sodium?

Answer 34

Renin-angiotensin-aldosterone

Question 35

What conditions lead to hyponatremia?

Answer 35

- Excess retention or intake of H2O - Inappropriate or uncontrolled secretion of ADH - Increased loss or decreased intake of Na+

Question 36

What conditions lead to hypernatremia

Answer 36

- Impaired thirst - No access to drinking H2O - Loss of extracellular H2O

Question 37

Acute water load

Answer 37

Osmolarity < 290 - Drink free H2O - Increased ECF volume, decreased ECF osmolarity - Shift of water from ECF to ICF: Decreased  ICF osmolarity - New steady state: Hypoosmotic volume expansion, TBW increases

Question 38

Infusion of isotonic NaCl

Answer 38

- Increased ECF volume - No change in osmolarity, as infusion is isosmotic - No need for fluid shift - ICF volume remains unchanged - New steady state: Isosmotic volume expansion - TBW increases

Question 39

What does the renin-Ang II-Aldo system regulate?

Answer 39

- Arterial pressure by regulating blood volume - Achieved by regulating Na+ reabsorption --> affects H2O reabsorption - Amount of Na+ in ECF determines volume

Question 40

Production of hyposmotic urine

Answer 40

W/out ADH, H2O reabsorption does not occur in late DT & CD. - A dilute urine is produced - H2O is impermeable to thick ascending limb & CD

Question 41

Production of hyperosmotic urine

Answer 41

- When ADH is present, a concentrated urine is formed - H2O is impermeable to thin ascending limb - H2O reabsorption is maximal at CD