B3

Question 1

What is the primary role of the kidney?

Answer 1

To remove urea from the blood and perform osmoregulation.

Urea is produced in the liver when excess amino acids are broken down.

Question 2

How many kidneys do mammals typically have?

Answer 2

Two kidneys.

The kidneys are located on either side of the aorta at the rear of the abdomen.

Question 3

What is the functional unit of the kidney?

Answer 3

The nephron.

There are 1-2 million nephrons per kidney.

Question 4

What are the main structures involved in the nephron?

Answer 4

• Bowman’s capsule
• Glomerulus
• Proximal tubule
• Distal tubule
• Loop of Henle
• Collecting duct

Structures in the cortex filter toxins like urea from the blood.

Question 5

What is the function of the Bowman’s capsule?

Answer 5

It allows fluid to leave blood while preventing cells and large proteins from passing into the tubule.

The Bowman’s capsule has little resistance to fluid leaving the blood.

Question 6

What is the role of the proximal tubule in the nephron?

Answer 6

It is involved in rapid absorption of filtered fluid.

Adaptations include a large surface area due to microvilli and many mitochondria for ATP production.

Question 7

What is osmoregulation?

Answer 7

The process of maintaining the balance of water and electrolytes in the body.

This is an important function of the nephron.

Question 8

Fill in the blank: The kidneys filter around _______ of fluid out of the blood each day.

Answer 8

180 dm³

Question 9

What structures are located in the cortex of the kidney?

Answer 9

• Bowman’s capsule
• Glomerulus
• Proximal tubule
• Distal tubule

These structures are mostly concerned with filtering toxins from the blood.

Question 10

True or False: The ureter carries urine to the bladder.

Answer 10

True

Question 11

What adaptations do the walls of the proximal tubule have?

Answer 11

A large surface area due to microvilli and many mitochondria.

These adaptations facilitate rapid absorption.

Question 12

What does the collecting duct do?

Answer 12

It collects urine from the nephron and carries it to the renal pelvis.

The collecting duct is crucial for urine concentration.

Question 13

What is the primary function of the kidneys?

Answer 13

The kidneys remove urea from the bloodstream by ultrafiltration.

Question 14

What is ultrafiltration?

Answer 14

The first stage in producing urine is the filtering of blood in the Bowman’s capsule.

Question 15

What factors influence the filtration process in the kidneys?

Answer 15

• Particle size
• Blood pressure
• Afferent arteriole width compared to efferent arteriole

Question 16

Where does the majority of filtrate return to the blood?

Answer 16

In the proximal convoluted tubule (PCT).

Question 17

How much water is filtered and how much is reabsorbed?

Answer 17

Filtered: 180 dm3, Reabsorbed: 179 dm3

Question 18

What happens to glucose during selective reabsorption?

Answer 18

Useful substances such as glucose are fully reabsorbed.

Question 19

What is the concentration of urea in blood plasma and urine?

Answer 19

Blood plasma: 54 g, Urine: 30 g

Question 20

What promotes filtrate formation in the kidneys?

Answer 20

• Blood enters the glomerulus under pressure
• Afferent arteriole is wider than efferent arteriole

Question 21

What substances are actively reabsorbed in the kidneys?

Answer 21

• Glucose
• Amino acids
• Proteins
• Vitamins
• Hormones
• Sodium ions

Question 22

What is the role of the distal convoluted tubule (DCT)?

Answer 22

The DCT secretes waste chemicals such as creatinine into the filtrate.

Question 23

What is the function of the loop of Henle?

Answer 23

It produces a very high concentration of solutes in the medulla of the kidney.

Question 24

What does the loop of Henle allow mammals to produce?

Answer 24

Urine more concentrated (hypertonic) or less concentrated (hypotonic) than plasma.

Question 25

What is the permeability of the descending limb of the loop of Henle?

Answer 25

Permeable to water.

Question 26

What is the permeability of the ascending limb of the loop of Henle?

Answer 26

Impermeable to water.

Question 27

What does finding plasma protein in urine suggest?

Answer 27

Damage to kidney membranes, often caused by high blood pressure.

Question 28

What does finding glucose in urine indicate?

Answer 28

Possible damage to the reabsorption mechanism or high blood glucose concentration.

Question 29

What is a countercurrent multiplier in relation to the loop of Henle?

Answer 29

The flow of filtrate in the two limbs is in opposite directions.

Question 30

Fill in the blank: The loop of Henle is a _______ multiplier.

Answer 30

countercurrent

Question 31

What hormone is released by the pituitary gland to control plasma concentration?

Answer 31

Antidiuretic hormone (ADH) ## Footnote ADH affects the permeability of the kidney tubules to water.

Question 32

What is osmoregulation?

Answer 32

The control of water potential of body fluids ## Footnote It is an example of a negative feedback mechanism.

Question 33

What controls the amount of ADH released by the pituitary?

Answer 33

Nervous stimulation from the hypothalamus

Question 34

What happens to urine volume without ADH?

Answer 34

High volumes of dilute urine are produced ## Footnote This occurs because hypotonic filtrate passes through the collecting duct unchanged.

Question 35

How does ADH affect urine concentration?

Answer 35

It controls the concentration and volume of urine produced by the kidneys

Question 36

What are the two properties of fluids in the kidney that affect ADH's action?

Answer 36

1. The filtrate at the end of the loop has a higher water potential than plasma 2. The medulla has a very low water potential

Question 37

What effect does ADH have on the collecting duct?

Answer 37

It causes channels to open, allowing water to pass through ## Footnote This results in water leaving the filtrate by osmosis.

Question 38

Why do kangaroo rats produce very concentrated urine?

Answer 38

To conserve water in arid environments

Question 39

What adaptations do kangaroo rats have for water conservation?

Answer 39

1. Nephrons with very long loops of Henle 2. More microvilli in tubules 3. More mitochondria for efficient reabsorption

Question 40

What is the role of the loop of Henle in urine concentration?

Answer 40

It creates a very low water potential in the medulla

Question 41

Fill in the blank: The __________ is responsible for controlling the amount of ADH released.

Answer 41

hypothalamus

Question 42

True or False: ADH makes the walls of the collecting duct impermeable to water.

Answer 42

False

Question 43

What is the role of the kidney in maintaining balance in the body?

Answer 43

The kidney helps maintain balance by regulating the amount of water in plasma, maintaining blood pressure and electrolyte balance, and regulating the pH of the plasma. ## Footnote The kidney plays a crucial role in homeostasis.

Question 44

What mechanism does the kidney use to maintain blood pressure?

Answer 44

The renin-angiotensin-aldosterone mechanism. ## Footnote This mechanism involves several steps to increase blood pressure when it decreases.

Question 45

What happens in the kidneys when blood pressure decreases?

Answer 45

Juxtaglomerular cells of the kidneys release increased renin, which leads to the production of angiotensin I and II, resulting in increased blood pressure. ## Footnote The process involves multiple organs including the liver and lungs.

Question 46

How do kidneys regulate electrolyte balance?

Answer 46

By increasing aldosterone which leads to increased Na+ and water reabsorption and increased secretion of K+ and H+ into urine. ## Footnote This process helps maintain homeostasis in body fluids.

Question 47

What is the normal pH range for fluids in the human body?

Answer 47

Between pH 7.35 and 7.45. ## Footnote Outside of this range, proteins such as enzymes may become denatured.

Question 48

What does pH stand for?

Answer 48

Potential of hydrogen. ## Footnote A low pH indicates an acidic solution, while a high pH indicates an alkaline solution.

Question 49

What is the consequence of kidney failure?

Answer 49

The kidneys stop removing toxic waste from the blood, leading to a buildup of toxins such as urea. ## Footnote This can be fatal if not treated.

Question 50

What is the function of a dialysis machine?

Answer 50

It removes waste products and balances the levels of water and salts in the blood. ## Footnote Dialysis is necessary for individuals with kidney failure.

Question 51

How often do patients typically need dialysis?

Answer 51

Three to four times a week for 4-5 hours each session. ## Footnote This is essential for managing kidney failure.

Question 52

What is involved in a kidney transplant?

Answer 52

A single healthy kidney from a donor is joined to the blood vessels and bladder of the recipient. ## Footnote Successful transplants can restore kidney function.

Question 53

What challenge does the recipient face after a kidney transplant?

Answer 53

The recipient's immune system may reject the new kidney due to differences in antigens. ## Footnote Finding a closely matched donor is crucial.

Question 54

What are immunosuppressant drugs used for in kidney transplants?

Answer 54

To suppress the immune system and prevent rejection of the transplanted kidney. ## Footnote These drugs are vital for transplant success.

Question 55

Fill in the blank: A base is a substance that produces _______ ions in solution.

Answer 55

hydroxide (OH*) ## Footnote Bases can also accept hydrogen ions.