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Question 1

What is the primary purpose of the excretory system?

Answer 1

To filter and remove wastes from the body fluids of an organism

Question 2

What are the three main layers of the kidney?

Answer 2

• Cortex (outer layer of connective tissue)
• Medulla
• Renal Pelvis (connected to the ureter)

Question 3

What is the primary site of filtration in the kidney?

Answer 3

Medulla

Question 4

How many nephrons does a kidney contain approximately?

Answer 4

About 1 million nephrons

Question 5

What is the glomerulus?

Answer 5

The first part of the nephron where blood plasma and its solutes flow into the Bowman’s capsule

Question 6

Which substances do not normally pass from the glomerulus into the Bowman’s capsule?

Answer 6

• Proteins
• Erythrocytes (RBCs)
• Platelets

Question 7

What is the sequence of structures that filtrate passes through after the Bowman’s capsule?

Answer 7

Proximal tubule → Loop of Henle → Distal tubule → Collecting duct → Ureter → Bladder

Question 8

What substances are reabsorbed at the proximal tubule?

Answer 8

• HCO3-
• NaCl
• H2O
• Nutrients
• K+

Question 9

What occurs at the descending loop of Henle?

Answer 9

H2O is reabsorbed into capillaries

Question 10

What is reabsorbed in the ascending loop of Henle?

Answer 10

NaCl is reabsorbed into the capillaries

Question 11

What happens at the distal tubule?

Answer 11

HCO3-, NaCl, and H2O are reabsorbed into capillaries

Question 12

What is the role of the collecting duct?

Answer 12

Reabsorbs NaCl, H2O, and some urea into capillaries

Question 13

What is active transport?

Answer 13

The process by which substances are moved against their concentration gradient

Question 14

What type of molecules are secreted back into the nephron?

Answer 14

• H+ (acids)
• Excess minerals (e.g., Na+, K+)
• Nitrogenous wastes (e.g., urea, creatinine, uric acid, ammonia)
• Drugs

Question 15

What is Antidiuretic Hormone (ADH)?

Answer 15

A hormone that increases water reabsorption in the distal tubule and collecting duct

Question 16

What triggers the release of ADH?

Answer 16

Low blood pressure, dehydration, or during sleep

Question 17

What hormone is released by juxtaglomerular cells when low blood flow is detected?

Answer 17

Renin

Question 18

What does renin convert angiotensinogen into?

Answer 18

Angiotensin I

Question 19

What is the role of ACE (angiotensin converting enzyme)?

Answer 19

Turns angiotensin I into angiotensin II

Question 20

What does angiotensin II stimulate?

Answer 20

• Vasoconstriction
• Release of ADH
• Release of aldosterone

Question 21

What is aldosterone’s function?

Answer 21

Stimulates thirst and increases NaCl and water reabsorption in the nephron

Question 22

What are kidney stones?

Answer 22

Mineral solutes in the blood that precipitate into stones causing damage to the kidney

Question 23

What condition results from low insulin levels leading to high blood glucose?

Answer 23

Diabetes Mellitus

Question 24

What is the effect of high glucose concentrations in nephron filtrate?

Answer 24

Shifts osmotic balance, drawing water into urine instead of back into capillaries

Question 25

What occurs in Diabetes Insipidus?

Answer 25

Very little water reabsorption occurs due to lack of ADH

Question 26

What is nephritis?

Answer 26

Inflammation of the kidney, leading to reduced glomerular blood flow and decreased urine production

Question 27

How do single-celled organisms excrete materials?

Answer 27

Via exocytosis and contractile vacuoles for excess water

Question 28

What is the function of nephrostomes in annelids?

Answer 28

L Collect waste-containing coelomic fluids and funnel them into metanephridia

Question 29

What do metanephridia do?

Answer 29

Reabsorb valuable substances and allow wastes to continue to nephridiopores

Question 30

What is the role of malpighian tubules in arthropods?

Answer 30

Filter water and solutes from hemolymph