2 Homeostasis and excretion

Question 1

What is homeostasis?

Answer 1

Maintaining constant conditions in the body, maintaining a constant internal environment.

Question 2

What things do we have to keep at a constant?

Answer 2

• Level of carbon dioxide in the blood.
• The bloods pH.
• The concentration of dissolved glucose.
• Body temperature.
• Water content.

Question 3

What do the kidneys excrete?

Answer 3

Urine and in that is urea.

Question 4

What do the lungs excrete?

Answer 4

• Carbon dioxide.
• Water.

Question 5

What does the skin excrete?

Answer 5

Excess water and salts, as well as a small amount of urea.

Question 6

What does the skin do when it detects an increase in body temperature?

Answer 6

This signal is sent to the thermoregulatory center in the hypothalamus:
- Hair erector muscles relax.
- Increased sweating means a loss of heat by evaporation.
- Vasodilation means for the widening of blood vessels which increases radiation

Question 7

What does the skin do when it detects a decrease in body temperature?

Answer 7

• Hairs erect to trap heat.
• Vasoconstriction, blood cells constrict so the blood flows through deeper vessels.
• Less sweating.
• Skeletal muscles contract and relax - shivering.