10.1: The Excretory System

Question 1

What does the excretory system do?

Answer 1

Regulate the volume and composition of body fluids by excreting metabolic waste and recycling some substances for reuse

Question 2

What are the main organs of the excretory system?

Answer 2

Kidneys, urethra, urea, bladder, afferent and efferent arterioles

Question 3

What are the four main functions of the excretory system?

Answer 3

1) Excretion of metabolic waste
2) Maintenance of water-salt balance
3) Maintenance of acid-base balance
4) Secreting hormones

Question 4

What are the 3 regions of the kidney?

Answer 4

1) Cortex
2) Medulla
3) Renal Pelvis

Question 5

What is the role of the nephron?

Answer 5

Filter wastes while reabsorbing water and other vital materials

Question 6

What are the 3 parts that make up a nephron?

Answer 6

1) The Filter
2) Tubules
3) The Duct

Question 7

Explain the function and location of the Bowman’s capsule

Answer 7

• Cap-like formation at the top of each nephron that acts like a filtration structure
• Surrounds the glomerulus and found in the renal cortex

Question 8

Explain the function, process, and location of the Glomerulus

Answer 8

• Knot of capillaries inside the Bowman’s capsule
• Walls of glomerulus acts as a filtration device
• Waste of metabolism pass through walls of the nephron
• Walls are impermeable to large molecules, which remain in the blood

Question 9

What is the difference between the afferent and efferent arteriole?

Answer 9

Afferent: Carries blood toward the glomerulus
Efferent: Carries blood away from the glomerulus

Question 10

Explain the function and location of the proximal convoluted tubule

Answer 10

• Found in the renal cortex
• Narrow region of the nephron after the Bowman’s capsule
• Connects the Bowman’s capsule and and the Loop of Henle
• Main function is the reabsorption of solutes and water
• Involves active and passive transport methods

Question 11

Explain the function and location of the loop of Henle

Answer 11

• Found in the renal medulla
• Consists of a descending limb which allows water to leave the filtrate
• Consists of an ascending limb where ions (Na, Cl, K) leave the filtrate and are reabsorbed into the bloodstream

Question 12

Explain the function and location of the distal convoluted tubule

Answer 12

• Found in the renal cortex
• Reabsorbs solutes and water
• Last tubule found after the end of the Loop of Henle

Question 13

Explain the function and location of the collecting duct

Answer 13

• Functions as a water conservation device, reabsorbing water into the filtrate
• Area where urine is collected in the kidney
• Distal convoluted tubules of several nephrons enter one collecting duct
• Many collecting ducts in each kidney carry the urine to the renal pelvis where it’s found in the renal medulla

Question 14

Explain the excretion of metabolic wastes

Answer 14

• Nitrogenous wastes (ammonia, urea, and uric acid
• Ammonia is highly toxic and is converted to urea in the liver

Question 15

Explain maintaining the water-salt balance

Answer 15

• Maintain an appropriate balance between water and salt in the blood
• Regulating salt and water in the blood maintains blood pressure
• Maintains an appropriate level of Na, K, and HCO3 in the blood

Question 16

Explain maintaining the acid-base balance

Answer 16

• Kidneys monitor the pH of the blood and maintain it at 7.4by excreting H ions and reabsorbing HCO3 ions when needed

Question 17

Explain the secretion of hormones

Answer 17

• Kidneys assist the endocrine system in secreting hormones
• Secretes calcitriol and erythropoietin

Question 18

Approximately how many nephrons are in each kidney?

Answer 18

1 million in each kidney

Question 19

What does a longer loop of Henle do?

Answer 19

Helps with the absorption of more water

Question 20

What is the cortex of the kidney?

Answer 20

The outer layer

Question 21

What is the medulla of the kidney and what does it consist of?

Answer 21

• The inner layer beneath the cortex
• Consists of renal-pyramids

Question 22

What is the renal pelvis and what does it do?

Answer 22

• Hollow chamber where collecting ducts join and empty into the ureter

Question 23

Explain the function of calcitriol

Answer 23

Is the active form of vitamin D which promotes Ca absorption in the digestive tract

Question 24

Explain the function of erythropoietin

Answer 24

Stimulates the production of RBCs and is released in response to either increased oxygen demand or decreased oxygen-carrying capacity of the blood