Homeostasis

Question 1

Why are communication systems necessary?

Answer 1

Metabolism relies on enzymes - certain conditions. Otherwise cell becomes inactive and dies. In multicellular, cells = specialised and rely on each other.

Question 2

What is homeostasis?

Answer 2

Maintains consent internal environment despite changes internal/external.

Question 3

What is the basic response pathway?

Answer 3

Stimulus -> receptor (detects changes + relays info to effectors) -> coordinator (transmit receptors to effectors) -> effector -> response

Question 4

What is negative feedback?

Answer 4

Mechanism for reversing a change so it returns to the optimum.

Question 5

What is the mechanism for negative feedback?

Answer 5

1. receptors detect change away from optimum - signal to coordinator
2. integrates info from different receptors to determine response
3. effectors create change -> conditions closer to optimum
4. receptor responds to decrease stimulus
5. output also decreases - effectors lowering activity

Question 6

What is positive feedback?

Answer 6

Increase deviation further from optimum. Large, unstable change in body. Normally harmful but can be useful.

Question 7

What is the difference in neuronal and hormonal systems?

Answer 7

Neuronal: between neurones via synapses, very fast, ST responses
Hormonal: via blood, endocrine glands, LT responses

Question 8

What are advantages and disadvantages of endotherms?

Answer 8

Maintain temp if external changes, remain active and live if colder BUT can overheat as own energy source, lots of energy used so need more food.

Question 9

What are advantages and disadvantages of ectotherms?

Answer 9

More energy for growth and find less food BUT less active if cold - predators, smaller habitat range.

Question 10

Why are good communication systems needed?

Answer 10

• cover whole body - all can communicate
• specific to stimulus
• long and short responses

Question 11

How do endotherms control their temperature?

Answer 11

Relies on heat from metabolic reactions to regulate temp.
Too cold; increase respiration rate, hairs erect, vasoconstriction, cell respiration increases.
Too hot; sweat glands, can pant, vasodilation.

Question 12

How do endotherms react quickly to temperature changes?

Answer 12

Peripheral temp receptors in skin relay to hypothalamus. Respond faster, before blood temp changes so decreases variation in core temp.

Question 13

How do ectotherms control their temperature?

Answer 13

Relies on external heat sources.
Too cold; move out shade, increase SA in sun, move to warmth.
Too hot; move out sun, decrease SA in sun, move underground.