Renal Control

Question 1

What is tubular reabsorption?

Answer 1

Transfer of substances from tubular lumen into peritubular capillaries

Question 2

How is sodium reabsorbed in the kidney?

Answer 2

By active transport

Question 3

How are anions reabsorbed in the kidney?

Answer 3

Electrochemical gradient

Question 4

How is water reabsorbed in the kidney?

Answer 4

By osmosis

Question 5

How are permeable solutes reabsorbed in the kidney?

Answer 5

• Diffusion through membrane
• Paracellular pathway

Question 6

Where is the most sodium reabsorbed in the kidney?

Answer 6

In the proximal tubule

Question 7

How much of sodium is reabsorbed at the proximal tube?

Answer 7

70%

Question 8

Where is the second most sodium reabsorbed in the kidney?

Answer 8

In the thick ascending limb

Question 9

How much of sodium is reabsorbed at the thick ascending limb?

Answer 9

20%

Question 10

How much of sodium is reabsorbed at the distal tube?

Answer 10

6%

Question 11

How much of sodium is reabsorbed at the collective duct?

Answer 11

3%

Question 12

What percent of sodium is secreted?

Answer 12

1%

Question 13

Where is the urine most concentrated?

Answer 13

The loop of henle

Question 14

How is osmotic gradient maintained?

Answer 14

Countercurrent exchange between the loop of henle and vasa recta

Question 15

What is the ascending limb permeable to and what does that result in?

Answer 15

Only permeable to solute resulting in the filtrate becoming more dilute

Question 16

What is the descending limb permeable to and what does that result in?

Answer 16

Only permeable to water resulting in filtrate becoming more concentrated

Question 17

Where is the only place urine concentration can be varied?

Answer 17

In the distal tubule and collecting ducts

Question 18

What are the three hormones which regulate the concentration of urine?

Answer 18

• Vasopressin
• Aldosterone
• Natriuretic peptides

Question 19

How does vasopressin influence concentration of urine?

Answer 19

Insertion of aquaproins into membrane facilitates water uptake which decreases volume of urine and increases urine concentration

Question 20

How does aldosterone influence concentration of urine?

Answer 20

Increases sodium reabsoprtion and potassium secretion resulting in smaller volume of urine and decreased urine concentration

Question 21

What activates the renin angiotension system?

Answer 21

By a reduction in NaCl and extracellular fluid volume and arterial blood pressure

Question 22

What triggers natriuretic peptides?

Answer 22

Increased blood pressure

Question 23

How does natriuretic peptides influence concentration of urine?

Answer 23

Leads to increased secretion of sodium in the urine resulting larger volume of urine and decreased concentration

Question 24

What controls the potassium balance in the body?

Answer 24

Aldosterone

Question 25

What is hypokalaemia?

Answer 25

Low levels of potassium resulting in muscle weakness

Question 26

What is hyperkalaemia?

Answer 26

Increased levels of potassium resulting in cardiac arrhythmias

Question 27

What triggers thirst?

Answer 27

Increase in blood osmolarity above 280 mOsM

Question 28

How much liquid can the bladder roughly hold?

Answer 28

500mL

Question 29

What is micturition?

Answer 29

The action of urinating

Question 30

What is the six steps for triggering urination?

Answer 30

- Stretch receptors fire - Parasympathetic neurones fire - Motor neurons stop firing - Smooth muscle contracts - Internal sphincter is passively pulled open - External sphincter relaxes