Homeostasis

Question 1

What are the variables the body needs to control (5)

Answer 1

• Temperature
• pH
• Blood glucose
• Salt/water balance
• Blood pressure

Question 2

What’s the difference between regulated + non-regulated variables

Answer 2

Regulated = directly sensed + controlled
Nonregulated = indirectly sensed + controlled

Question 3

Give examples of regulated variables (3)

Answer 3

• Blood pressure
• Blood pH
• Blood O2/CO2 partial pressure

Question 4

Give examples of non-regulated variables (2)

Answer 4

• Heart rate
• Breathing rate

Question 5

Describe the homeostasis process (3)

Answer 5

1. Detect changes (receptor/sensor)
2. Process signal + determine action (brain)
3. Change body state (effector)

Question 6

Describe negative feedback loop (4)

Answer 6

1. Deviation from set point
2. Detected by receptor
3. Info sent to control centre (brain via CNS)
4. Counteract change via effector (physiological/behavioural)
   - Mechanism can turn itself off

Question 7

Describe positive feedback

Answer 7

• Uncommon mechanism
• Sensor detects change
• Organ systems amplify response (eg. uterus stretch during labor)