Homeostasis

Question 1

What is homeostasis?

Answer 1

The maintenance of a stable internal state

Question 2

What is negative feedback?

Answer 2

A physiological response in the opposite direction to a change (shivering when cold)

Question 3

What are the different systems for negative feedback?

Answer 3

Sensor, integrator and effector

Question 4

What is the purpose of a sensor?

Answer 4

Detects a change

Question 5

What is the purpose of an integrator?

Answer 5

Compares the change from a set-point

Question 6

What is the purpose of an effector?

Answer 6

Induces response to get back to set-point

Question 7

What is antagonistic control?

Answer 7

Changes of a variable in both directions (shivering when cold and sweating when hot)

Question 8

Disadvantages of negative feedback

Answer 8

• Delays in response as integrator needs time to detect a change
• Delay when stopping negative feedback as effector needs time to stop the change
• May not occur in extreme conditions

Question 9

Adaptations of negative feedback

Answer 9

Anticipation: predicts changes before they occur and can stop negative feedback before it overshoots the set-point
Acclimatisation: adaptation that alters negative feedback gradually (adding fat layers in autumn to get ready for winter)

Question 10

Changing set points

Answer 10

Set points can change temporarily, permanently or cyclically

Question 11

What is positive feedback?

Answer 11

A physiological response in the same direction as a change

Question 12

What is enantiostasis?

Answer 12

Maintaining homeostasis by changing one physical variable due to a change in another variable

Question 13

3 classes of animals for homeostasis

Answer 13

Conformers- internal state matches external environment (most animals)
Regulators- maintain constant internal state (mammals)
Avoiders- maintain internal state by avoiding environmental change (migrators)

Question 14

The cell

Answer 14

• Smallest unit of organisation capable of processes associated with life
• Obtain nutrients and energy sources, produce energy, eliminate waste and synthesise protein to maintain shape and for cellular function
• Maintain constant internal state and can control exchange molecules

Question 15

Examples of specialised cells

Answer 15

Gland cells (secretion of molecules), neurons (electrical conductivity), kidney cells (material exchange) and muscle cells (movement)

Question 16

Tissue

Answer 16

Groups of cells with similar specialised functions which are used to make up organs

Question 17

Organism

Answer 17

Collection of systems (2 or more organs) separate from external environments

Question 18

Difference between single cell organisms and animals

Answer 18

Single cell organisms regulate via direct contact with exterior whereas animals regulate via no contact with exterior. Single cell organisms are surrounded by an internal fluid to undergo homeostasis.

Question 19

Intrinsic vs Extrinsic

Answer 19

Intrinsic: regulated by one tissue type or organ (quick)
Extrinsic: regulated by different organ systems (slow)

Question 20

Control systems

Answer 20

Regulate homeostasis indirectly via other systems (nervous and endocrine systems)

Question 21

Maintenance systems

Answer 21

Regulates homeostasis directly (Respiratory, circulatory, digestive,
excretory, integumentary and immune system)