Excretion

Question 1

What is excretion?

Answer 1

The removal of metabolic waste from the body.

Question 2

What are the two ways in which the excretory system plays a role in homeostasis?

Answer 2

• by maintaining the composition of an organism’s fluids,
  including fluid balance and chemistry.
• by preventing the accumulation of poisonous wastes which
  might interfere with metabolism.

Question 3

What is homeostasis?

Answer 3

Homeostasis is the maintenance of a

constant internal environment within the body.

Question 4

What are the main waste products of the exretory system?

Answer 4

• Water
• Carbon dioxide
• Nitrogenous (nitrogen-containing) wastes.

Question 5

What do the lungs remove?

Answer 5

• Carbon dioxide

- Water

Question 6

In the liver, what are excess amino acids split into?

Answer 6

A carbohydrate and urea.

Question 7

What do sweat glands excrete?

Answer 7

They excrete water and some salts.

Question 8

What does the urinary system consists of?

Answer 8

• Kidneys
• Ureters
• Urinary bladder
• Urethra

Question 9

How do the kidneys work?

Answer 9

• The kidneys work by filtering the blood and then absorbing back what the body needs to keep. The wastes are allowed pass to the bladder, for storage and release.
• When urine is being produced, it flows into the renal pelvis, into the ureter then, the bladder.

Question 10

How does reabsorption in the kidneys work?

Answer 10

• Blood vessels reabsorb back useful nutrients
  from the tubules.
• Urea, excess salts and water, are allowed to continue down the tubule and on to the bladder.

Question 11

What is the filtration system of the kidneys?

Answer 11

In the outer cortex, small molecules like glucose,

amino acids, water, urea and salts filter out of the blood into narrow tubules.

Question 12

What is secretion?

Answer 12

Secretion is the production and release of chemicals

from cells.

Question 13

What is urine composed of?

Answer 13

• Urine is composed of:
• Water (96%)
• Urea
• Salt
• Traces of other substances (such as hormones).

Question 14

What are the ways that water is lost from the body?

Answer 14

• Lungs - some water gets evaporated as we exhale from our
  warm, damp lungs.
• Skin - by evaporation from cells and through sweat.
• Intestines - in the faeces (undigested food).
• Kidneys - in dissolving the poisons and wastes we wish to
  excrete from the body.

Question 15

What are endotherms?

Answer 15

An animal that is dependent on or capable of the internal generation of heat.

Question 16

What are endotherms?

Answer 16

An animal that is dependent on external sources of body heat.

Question 17

What is the role of Skin in Homeostasis?

Answer 17

The role of skin in homeostasis is temperature regulation.

Question 18

What is the role of Skin as an excretory organ?

Answer 18

The role of skin as an excretory system is for the removal of sweat.

Question 19

What is the core temperature of a human?

Answer 19

37 degrees Celsius.

Question 20

What three parts of the human body play a role in body temperature?

Answer 20

• Muscles
• Skin
• Blood

Question 21

What happens if our temperature rises?

Answer 21

More blood flows closer to the surface of the skin and sweat glands release sweat.

Question 22

What happens if our temperature drops?

Answer 22

Blood flows beneath the adipose tissue, we stop sweating, our hairs stand up and we shiver.

Question 23

What is the structural and functional unit of the kidney?

Answer 23

The structural and functional unit of the kidney is the nephron.

Question 24

Describe the renal artery.

Answer 24

The renal artery divides into afferent arterioles and then into a capillary network (glomerulus) at the top of each nephron.

Question 25

What happens if you drink a lot of water?

Answer 25

• The hypothalamus in the brain detects the diluted blood and turns off ADH production.
• Less water is reabsorbed, so more water is allowed
  to escape to the bladder.
• Larger volume of dilute urine is produced.

Question 26

What happens when the body is low on water?

Answer 26

• ADH is secreted from the pituitary gland.
• More water is reabsorbed.
• Only a small volume of urine is produced.