Renal Physiology

Question 1

How does the kidney regulate systemic renin-angiotensin system activity?

Answer 1

Kidney afferent arterioles contains stretch receptors that will respond to decreased/increased stretch by feedback to RAS.

Question 2

How does the kidney eliminate waste (in short)

Answer 2

Hydrostatic pressure in the capillary bed forces fluid & stuff out through pores (selective convection)

Question 3

How do we quantify kidney convection?

Answer 3

Glomerular filtration rate

Question 4

What determines GFR?

Answer 4

1. Renal Area (having enough filtration barrier)
2. Renal blood flow (plasma volume)
3. Starling forces (net ultrafiltration pressure)

Question 5

What is the role of the proximal convoluted tubule?

Answer 5

1. Reabsorption: Na and water, glucose

2. Secretion: Large/poorly filtered molecules

Question 6

How is the kidney involved in hormone production and regulation?

Answer 6

1. Epo: produced in kidney, RBC production stimulant
2. Insulin: metabolism
3. Vitamin D: activation

Question 7

What is the function of the loop of Henle?

Answer 7

1. Creation of dilute urine (reabsorption of Na/H20)
2. Concentration of urine (countercurrent multiplier)
3. Influences GFR via tubuloglomerular feedback

Question 8

How is the hypertonic interstitium create and maintained?

Answer 8

1. Countercurrent exchanger: blood flow to nephron via vasa recta is very slow, allowing equilibration and maintenance of hypertonicity

Question 9

What is the function of the distal convoluted tubule?

Answer 9

Na reabsorption (small)
Final "decision" on quantity of Mg and Ca excreted

Question 10

What is the main function of the collecting duct?

Answer 10

“Fine tuning” of urine: Na/K concentrations, water reabsorption, pH

Question 11

Why is the regulation of water important?

Answer 11

Otherwise your brain explodes or shrivels!!!

Question 12

How do we regulate today body H20?

Answer 12

Brain and kidneys work together: brain senses, kidney regulates excretion

Question 13

How does the brain sense water homeostasis?

Answer 13

Osmoreceptors in hypothalamus detect “effective osmoles” (Sodium)

Question 14

What hormone systems are involved in total body water?

Answer 14

1. RAAS system: responds to stretch receptors in the afferent arteriole of the glomerulus, leads to activation of angiotensin II, which in turn causes ADH release, aldosterone release, (salt and water retained) and vasoconstriction.
   NOT RESPONSIVE TO SODIUM LEVELS

Question 15

How do I know when there is an abnormal amount of water?

Answer 15

There is an abnormal sodium.

Question 16

What is the effective arterial blood volume?

Answer 16

Volume of blood that is perfusing organs. Measure of how well the space is being filled (not equal to blood pressure)

Question 17

How do EABV and RAAS interact?

Answer 17

Drop in EABV will activate RAAS (less stretch), and salt and water will be retained

Question 18

What is edema?

Answer 18

High levels of interstitial fluid. Venous phenomenon