Question

a) What are some ways that reabsorption by diffusion and active transport could be limited in the kidneys?

b) What are two ways the kidneys could restore optimal Na + concentration?

c) How might the kidneys regulate Na + concentration during the night?

d) How would the concentration of Na + and water in the urine first thing in the morning be different from urine composition later in the day?

e) The kidneys help regulate blood pressure by controlling the volume of blood. When blood volume decreases, the pressure of the blood on arteries and veins decreases.

How can the kidneys reduce the volume of blood?

f) People with high blood pressure often take diuretics. A diuretic reduces Na + reabsorption. Explain how this would lower blood pressure.

Answer 1

a. Some ways that affect the reabsorption by diffusion and active transport in the kidney are amount of water in the blood, amount of ions like sodium, potassium and chloride in the blood, osmotic balance of blood.

b. The kidney could restore sodium concentration in the body fluid by

I. Secretion of alfosterone hormone by adrenal cortex.

II. Passive water reabsorbtion in the blood.

c. The kidney maintain the sodium ion regulation in the night by absorbing more water from the kidney filtrate so that sodium ion concentration remain constant.

d. During day time, urine amount will be high and less concentrated but at the night, the urine amount will be low and will be more concentrated. Less concentrated urine means there will be low sodium ion concentration and more water whereas high concerned urine means there will be high sodium ion concentration and less water.