Exam 3 | Renal

Question 1

What functions does the renal system perform?

Answer 1

filtration of blood & fluid homeostasis

osmoregulation

maintaining blood & plasma volumes

removing toxins from body

producing and secreting peripheral hormones and enzymes

Question 2

What’s osmoregulation?

Answer 2

the maintenance of water retention and ion/metabolite concentrations in the blood and other body fluids

Question 3

What are the 2 peripheral hormones/enzymes the renal system assists in?

Answer 3

Erythropoietin which is a protein that assists in the production of erythrocytes in response to cell loss/ damage

Renin is an enzyme that participates in the renal angiotensin-aldosterone system (RAAS)

Question 4

Where are the kidneys located?

Answer 4

lower thoracic/ upper abdominal cavity towards the dorsal/posterior region

Question 5

How does blood travel in the kidneys?

Answer 5

Renal artery: how the kidney receives blood

Renal vein: how blood travels out of the kidney

Question 6

How does filtrate (urine) leave the kidneys?

Answer 6

Urine leaves the body via 2 ducts, the ureters (1 per kidney), which carry urine to the bladder

Question 7

Describe the bladder

Answer 7

A semi-muscular sac that stores urine until the necessary/ appropriate time for voiding

Question 8

Describe the structure of the kidney.

Answer 8

The outer layer is the cortex & the inner layer is the medulla.

The nephron runs through both

Question 9

What is the smallest functional unit of the kidney?

Answer 9

the nephron

Question 10

What’s the nephron’s job?

Answer 10

It is the site of blood filtration in the kidney

Question 11

How many nephrons are in each kidney?

Answer 11

roughly 1 million

Question 12

Describe the structures of the nephron

Answer 12

Glomerulus: which actually filters unnecessary molecules out of the blood

Descending & ascending tube (tubule): relays the remaining filtrate (which eventually becomes urine) to the ureter

Question 13

What are the steps of blood filtration & urine formation?

Answer 13

1. Filtration
2. Reabsorption
3. Secretion
4. Excretion

Question 14

What happens in the first step (filtration)?

Answer 14

Blood enters the nephron via the renal artery where it encounters the glomerular capillaries. These are adjacent to the entrance to the loop of Henle (Bowman’s capsule). Here, only small molecules/ions pass through the glomerular capillaries

Question 15

What happens in the second step (reabsorption)?

Answer 15

After filtration, the filtrate is transferred to the descending loop where most of the water filtered out of the blood at the glomerulus returns to the body by diffusing out of the loop. Water is reabsorbed back into the body leaving high concentrations of small molecules/ions remaining in the filtrate as it is then transferred to the ascending loop.

Question 16

Why is the reabsorption step so important?

Answer 16

If it weren’t for reabsorption, we’d end up voiding a dangerous amount of water during a 24-hour period

Question 17

What happens in steps 3 and 4 (secretion & excretion)?

Answer 17

After the majority of the water leaves, the remaining filtrate passes through the ascending loop and collecting duct. Here, the osmolarity of the filtrate is rebalanced through some water returning to the filtrate as well as active transport of ions out of the ascending loop. Here, filtrate is mixed with urea to be excreted via the ureter to travel to the bladder

Question 18

How does water return to the filtrate?

Answer 18

By specialized protein pumps, aquaporins

Question 19

What ions are being actively transported out?

Answer 19

Sodium and chloride

Question 20

What is urea?

Answer 20

A stable nitrogenous molecule compared to ammonia

Question 21

What hormone is responsible for regulating urine volume (water retention)?

Answer 21

The posterior pituitary hormone, antidiuretic hormone (ADH or vasopressin; for male reproductive system), is critical for adjusting the permeability of the collecting duct in the loop of Henle to water

Question 22

What are diuretics?

Answer 22

chemicals that result in less water retention; this leads to an increases volume of urine and an increased rate of voiding

coffee and alcohol are 2 common diuretics

Question 23

What happens when concentrations of ADH are high?

Answer 23

The amount of water reabsorbed into the collecting duct in the loop of Henle increases, resulting in a smaller volume of urine (more concentrated urine, darker in color)

Question 24

What happens when concentrations of ADH are low?

Answer 24

The amount of water reabsorbed into the collecting duct in the loop of Henles decreases, resulting in a larger volume of urine (more diluted and lighter in color)

Question 25

What roles do angiotensin and aldosterone play?

Answer 25

They play a critical role in helping to maintain a certain threshold of blood pressure by adjusting blood volume at the level of the nephron

Question 26

What happens when there’s a decrease in blood pressure?

Answer 26

The kidneys will secrete the protein renin, which triggers the production and secretion of angiotensin 1 (inactive); once acted upon by the enzyme, angiotensin-converting enzyme (ACE), it converts to angiotensin 2 (active protein); angiotensin 2 triggers the release of aldosterone and ADH both which act on collecting duct and loop of Henle.