5.1.1 Communication And Homeostasis

Question 1

What is homeostasis

Answer 1

The maintenance of a stable internal environment to ensure optimal cell function

Question 2

What features are involved in homeostasis

Answer 2

Receptors- detect stimuli and send signals to brain about changing environment
Coordinator- receives and interprets information from receptors
Effector- act on signals from the brain

Question 3

Negative feedback

Answer 3

Controls conditionsto keep them around optimum points
Deviations from optimum lead to changes to return system back to optimum conditions

Question 4

Positive feedback

Answer 4

Amplifies change
Deviations from optimum cause a greater deviations from optimum
(Childbirth, bloodclotting and action potential)

Question 5

What is cell signalling

Answer 5

Communication between cells to ensure responses are widespread

Question 6

How does cell signalling work?

Answer 6

Cells release hormones
Hormones travel by blood to target cells
Hormones binds to cell surface receptors
Response occurs via secondary messenger model

Question 7

Ectotherms

Answer 7

Use surroundings to regulated their body temperature via Behavioural changes
Internal temperature influenced by environmental temperatures.
Activity increases as temperature increases
Metabolic rate varies

Question 8

Endotherms

Answer 8

Rely on metabolic processes to control body temperatures, physiologically or behaviourally
Internal temperature relatively stable and less influenced by environment
Activity remains constant
Sustains steady metabolic rate

Question 9

What mechanisms occur when too hot?

Answer 9

Increased sweating- promotes evaporative cooling
Erector pili muscles relax- flattens hairs to reduce insulation
Vasodilation- increased blood flow to skin surface to increase heat loss via radiation

Question 10

What mechanisms occur when too cold

Answer 10

Shivering- skeletal muscles rapidly contract and relax to generate heat through increased cellular respiration
Reduced sweating- helps conserve heat
Erector pili muscles contract- raises hairs to trap an insulating layer of air
Vasoconstriction- arterioles constrict to reduce blood flow to skin surface so less heat is lost via radiation.

Question 11

How is body temperature controlled

Answer 11

Thermoreceptors in hypothalamus and peripheral receptors in skin detect changes in temperature.
Hypothalamus receives electrical signal and processes information. Hypothalamus sends signals to effectors to influence mechanisms to revert changes in body temperature