Removal of Waste in Animals

Question 1

Why are materials excreted?

Answer 1

accumulation of waste (from metabolism, growth and respiration) is toxic

Question 2

What are the wastes excreted, organs, and organ system involved in sweat?

Answer 2

wastes excreted: urea, water, salt

organ: skin, hair, nails
system: integumentary

Question 3

What are the wastes excreted, organs, and organ system involved in urine?

Answer 3

wastes excreted: urea, uric acid, ammonia
organs: kidneys, bladder
organ system: urinary

Question 4

What are the wastes excreted, organs, and organ system involved in exhaled air?

Answer 4

wastes excreted: carbon dioxide
organ: lungs
organ system: respiratory

Question 5

What are amino acids and why are they excreted?

Answer 5

nitrogen-containing molecules used by animals in synthesis of proteins and other compounds, e.g. creatine, peptide hormones, and some neurotransmitters.
Animals often consume more amino acids than necessary, so excess is converted to nitrogenous waste

Question 6

how is nitrogenous waste transported?

Answer 6

in the blood to the kidneys

Question 7

Where are the nephrons located?

Answer 7

in the cortex and medulla of the kidneys

Question 8

What do nephrons do?

Answer 8

they are excretory tubules which produce urine in the process of removing waste from the blood.

Question 9

Describe the structure of a nephron.

Answer 9

They are a long tubule, about 3-5cm. At one end is a cup-like structure called Bowman’s Capsule that encloses a cluster of blood capillaries called the glomerulus.

Question 10

Explain the process of filtration.

Answer 10

1. unfiltered blood containing waste enters the glomerulus through a narrow artery called the afferent arteriole.
2. Fluid from the blood diffuses into Bowman’s Capsule from the glomerulus.
3. This material, called filtrate, moves to the proximal tubule.

Question 11

What does filtrate contain

Answer 11

salts including sodium and chloride, as well as water, glucose, amino acids and nitrogenous wastes.
This composition is altered as certain materials are selectively reabsorbed into the blood capillaries surrounding the proximal tubule.

Question 12

What materials are reabsorbed in the proximal tubule, and why?

Answer 12

amino acids for protein synthesis
glucose for respiration
sodium ions for metabolism
water for metabolism

Question 13

What tissue lines the proximal tubule as an exchange surface?

Answer 13

epithelial tissue.

Question 14

Describe the properties of the epithelial tissue in the proximal tubule as an exchange surface.

Answer 14

Thickness of one cell and each cell has microvilli forming a brush border for surface area.

Question 15

Once materials have been selectively reabsorbed from filtrate, where does the excess go?

Answer 15

Moves out of the nephron via the collecting ducts.

Question 16

what do collecting ducts do?

Answer 16

drain into the ureters which transport urine to the bladder.

Question 17

What is osmoregulation?

Answer 17

The maintenance of the amount of solute (including glucose, sodium, potassium and chloride) in the body’s water supply.

Question 18

What does the pituitary gland do for osmoregulation?

Answer 18

it is in the brain, and responds to changes in blood osmolarity by regulating production and secretion of antidiuretic hormone (ADH).

Question 19

what does antidiuretic hormone (ADH) do/

Answer 19

it is transported in the blood to nephrons where it binds to receptors on epithelial cells. This causes the tubule and collecting duct to become more permeable to water, increasing the volume of water that is reabsorbed into the body (less is excreted in urine).

Question 20

If the volume of water in the blood is excessively high, state its osmolarity and describe the response

Answer 20

the osmolarity is below tolerance limit (not enough solutes in blood), so the pituitary gland decreases production of ADH and less water is reabsorbed, with more excreted in urine.

Question 21

if the volume of water in the blood is excessively low, state its osmolarity and describe the response

Answer 21

the osmolarity is above tolerance limit (too many solutes in blood) so the pituitary gland increases production of ADH and more water is reabsorbed, with less excreted in urine.