The Kidney/Nephron

Question 1

Albus has been for a jog in the countryside, and hasn’t drank enough water during his exercise, becoming quickly dehydrated. How does the body respond to this?

Answer 1

First of all, his body, or specifically the hypothalamus, would detect this decrease in water potential in the blood, and would begin to create ADH (Antidiuretic hormone), which is released by the Pituitary Gland into the bloodstream, where it flows through the body to the Kidney, and into the Nephron(s). Here, the hormones bind with receptors on the outside of the collecting duct, which increases permeability and causes the duct to open channels called aquaporins, which allows water to be absorbed back into the blood via osmosis, thereby increasing water potential in the blood.

Question 2

Albus stopped his exercise, and went to a local convenience store and bought a large bottle of water. He drank quite a lot of water to quench his thirst. How does his body respond to the change?

Answer 2

His hypothalamus would detect the increase in water potential throughout the body, and would begin to lessen the amount of ADH which is let into the body through the Pituitary Gland. Some hormones would still flow down to the Nephrons and their Collecting Ducts, however due to the lesser amount of ADH, less Aquaporins would be created, meaning less water is reabsorbed back into the body via osmosis.

Question 3

What arteriole enters the Glomerulus?

Answer 3

Afferent Arteriole

Question 4

What arteriole leaves the Glomerulus?

Answer 4

Efferent Arteriole.

Question 5

Describe Osmosis.

Answer 5

Osmosis is the process in which substances/water moves from a region of dilute to concentrated (in water), through a partially permeable membrane.

Question 6

How does Glucose get reabsorbed by the body?

Answer 6

Sodium Potassium pumps begin to move potassium into the PCT wall, and sodium out into the capillaries. This creates a concentration gradient, which pulls sodium into the PCT wall from its lumen. The glucose gets carried with the sodium as facilitated diffusion, via co-transport proteins. The glucose then travels via diffusion into the capillaries down another concentration gradient.

Question 7

1. What risks are involved with a Kidney transplant?

2. What risks are involved with Dialysis?

Answer 7

1. Bodily rejection, injection, lack of a donor. Immunosuppressants to control bodily rejection, may lead to further infections.
2. Job/life stress; 3+ times per week for up to 6-8 hours at a time.

Question 8

How are the cells of the PCT adapted to reabsorb glucose?

Answer 8

Microvilli to increase the surface area and allow greater diffusion/transportation of substances. Transport proteins to allow bigger molecules to pass through. Sodium/Potassium pump to create concentration gradient to pull glucose into the PCT wall.

Question 9

Describe the role of the kidney in:

1. Excretion
2. Osmoregulation

Answer 9

1. The kidneys are where the blood is filtered in the body. Here, they separate waste products from the useful blood, and this waste is brought together as urine, which moves from the blood to the bladder before excretion.
2. Getting rid of waste as urine is getting rid of water as well. The kidneys regulate water in the body by either letting more water exit the body, or by retaining more (via ADH), depending on the hydration level of the person.

Question 10

State the role of each structure)

1. Ureter
2. Kidneys
3. Bladder
4. Renal arteries
5. Renal veins
6. Urethra

Answer 10

1. Carries urine from the kidney to the bladder.
2. To filter blood from the body and remove waste products.
3. To store urine before it leaves the body via excretion.
4. Carries oxygen/mineral rich oxygen to the kidneys for ultrafiltration and waste removal.
5. Carries the cleaned, deoxygenated blood out of the kidneys to the heart/lungs.
6. Allows urine to exit the body via excretion.

Question 11

1. State what substances are forced out of the glomerulus in ultrafiltration?
2. State what causes these substances to be filtered?
3. State what substances are not able to be forced out of the glomerulus? Why?

Answer 11

1. Small molecules, such as water, glucose, amino acids, NaCl and urea.
2. A difference in pressure between the glomerulus and the inside of the PCT forces the substances to move into the tubular fluid.
3. Larger molecules, such as hemoglobin, due to its large size and inability to pass through the gaps in the membrane of the Nephron.