I/E: Homeostasis

Question 1

Homeostasis

Answer 1

Regulating your internal environment/keeping it roughly constant.

Question 2

What 3 things is it important to regulate in the body?

Answer 2

Core body temperature

Blood pH

Blood glucose

Question 3

What happens to enzymes if temperature is too high/too low?

Answer 3

Too high = enzymes might denature

Too low = enzyme activity is reduced, slowing the rate of metabolic reactions.

Question 4

What happens to enzymes if blood pH is too high or too low?

Answer 4

Enzymes become denatured.

Question 5

What does it mean if an enzyme is denatured?

Answer 5

• Hydrogen bonds that hold enzymes 3D shape are broken.
• Shape of active site is changed.
• No longer works as a catalyst.
• Metabolic reactions are less efficient.

Question 6

Why is it important to maintain the right concentration of glucose in the blood?

Answer 6

• Cells need glucose for energy.
• Blood glucose concentration affects the water potential of blood.

Question 7

What happens if blood glucose concentration is too high?

Answer 7

The water potential of blood is reduced to a point where water molecules diffuse out of cells into the blood by osmosis.

Cells can shrivel up and die.

Question 8

What happens if blood glucose concentration is too low?

Answer 8

Cells are unable to carry out normal activities because there isn’t enough glucose for respiration to provide energy.

Question 9

How do homeostatic systems respond to changes?

Answer 9

Negative feedback mechanisms.

Question 10

What is an issue with negative feedback mechanisms?

Answer 10

Only work within certain limits - of the change is too big then effectors may not be able to counteract change.

Question 11

Why is it beneficial that homeostasis involves multiple negative feedback mechanisms?

Answer 11

• More than one mechanism gives more control over changes in internal environments.
• Actively increase or decrease a level so it returns to normal, eg. mechanisms that increase body temp but also mechanisms that decrease it.
• With only one negative feedback mechanism, you could only actively change a level in one direction.

Question 12

What would happen if you only had one negative feedback mechanism?

Answer 12

The response would be slower and less controlled, as you could only actively change a level in one direction.

Question 13

Why can positive feedback be useful?

Answer 13

To rapidly activate something, eg. a blood clot after an injury.

• Platelets become activated and release a chemical.
• Triggers more platelets to be activated.
• Platelets quickly form a blood clot at the injury site.
• Process ends with negative feedback, when body detects the clot has been formed.

Question 14

What might occur if the homeostatic system breaks down?

Answer 14

Positive feedback, eg hypothermia.

• Body temp falling results in the brain not functioning properly.
• Shivering stops and temp falls even more.

Question 15

Is positive feedback involved in homeostasis? Why/why not?

Answer 15

No - it doesn’t keep your internal environment stable.