R 3

Question 1

why the Na and water need to stay in balance in the body?

Answer 1

• Total-body balance of Na and water must be maintained to sustain normal blood pressure and life.

Question 2

Average person in normal climate of Intake

Answer 2

• In liquid = 1200 ml
• In food (every food we intake contains water) = 1000 mL
• Metabolically produced = 350 mL

Question 3

Average person in normal climate of output

Answer 3

• Insensible loss (skin and lungs) the loss evaporation that we can’t feel or see = 900 mL
• Sweat = 50 mL
• Feces = 100 mL
• Urine = 1500 mL (most of the output. It’s important and it’s the only regulated portion of the output by the kidneys).

Question 4

water intake =

Answer 4

water output

Question 5

sodium intake =

Answer 5

sodium output

Question 6

depending on the intake, can the water and sodium output vary and how?

Answer 6

yes, Depending on intake: water output can vary from 0.4 L/day to 25 L/day; sodium chloride output can vary from 0.05 g/day to 25 g/day.

Question 7

filtration, secretion and reabsorption of sodium and water

Answer 7

• Both sodium and water are freely filtered but ~99% is reabsorbed (no secretion at the tubule).

Question 8

where happen the sodium and water reabsorption

Answer 8

• Most of the sodium and water reabsorption (~2/3) occurs in the proximal tubule.
• But the major hormonal control of reabsorption occurs on the DCT (distanl convoluted tubule) and CD (collecting duct)

Question 9

is the sodium reabsorption an active or not process?

Answer 9

Sodium reabsorption is an active process (we need ATP) occurring in all tubular segments (except the descending thin limb of Henle’s loop = no reabsorption of the sodium)

Question 10

the water reabsorption is made by …

Answer 10

diffusion and is dependent upon sodium reabsorption. It’s a passive diffusion process. (the major difference between them)

Question 11

Active sodium reabsorption