S1) Homeostasis

Question 1

The complex dynamic interaction of Matter, Energy and Fields in living cells is energy dependent.

Which 5 systems are required?

Answer 1

• Substrate supply system
• Product distribution system
• Waste removal system
• Stable controlled physicochemical environment (for reactions)
• Control systems (monitor & adjust)

Question 2

Describe the mechanisms behind homeostatic control in terms of:

• Control centre
• Receptor
• Effector

Answer 2

Question 3

What are the three types of signalling molecules?

Answer 3

• Endogenous – Within the body

- Exogenous I – Natural

- Exogenous II – Synthetic

Question 4

Identify 5 examples of physicochemical parameters under homeostatic control

Answer 4

• Temperature
• pH
• O₂
• CO₂
• H₂0

Question 5

In the following diagram, what function does the sensor have?

Answer 5

Sensor:

- Detects the physiological parameter

• Produces a signal related to parameter

Question 6

In the following diagram, what function does the controller have?

Answer 6

Controller:

- Generates an amplified signal proportional to disturbance

• Brings system output back towards set point

Question 7

In the following diagram, what function does the effector have?

Answer 7

Effector – bring about change back to optimal set point

Question 8

Identify the two ways in which homeostasis can act and provide examples

Answer 8

• Synergistically e.g. temperature – skin blood supply & sweating
• -* Antagonistically e.g. insulin vs glucagon signal

Question 9

Why does there need to be precise temperature regulation in our bodies?

Answer 9

• Most proteins operate optimally at 37°C
• At higher temperatures, enzymes denature
• Homeostasis reduce rate of thermal degradation of proteins

Question 10

Changes in thermal environment can be external and internal.

Provide an example of each.

Answer 10

• Muscle use leads to large and rapid increases in temperature locally and throughout the body
• Temperature of external environment can vary between +50^oC to -40^oC

Question 11

How does the body respond when body temperature exceeds 37^oC?

Answer 11

Response = LOSE HEAT

• Peripheral vessels dilate (heat radiates from skin surface)
• Sweat glands activated (increasing evaporative cooling)

Question 12

How does the body respond when body temperature falls below 37^oC?

Answer 12

Response = GAIN Heat

- Peripheral capillaries constrict (reducing heat loss from surface)

• Skeletal muscle shivers (generating more heat)

Question 13

What affect does signal transmission route integrity have on homeostasis?

Answer 13

• Transmission distance, velocity & time varies
• If delayed, homeostasis performance and physiological function are affected