Homeostasis - the principles

Question 1

Homeostasis definition

Answer 1

The maintenance of the internal environment in a constant state despite changes in external and internal factors.

Question 2

What does the body maintain?

Answer 2

Dynamic equilibrium, with small fluctuations within a narrow range

Question 3

What is the role of sensory receptors?

Answer 3

Detect changes in the internal or external environment of an organism.

Question 4

Response when information is transmitted from sensory receptors?

Answer 4

• sensory receptors transmit information to the brain
• impulses are sent along the motor neurons to effectors to bring about changes and restore equilibrium in the body.

Question 5

Effectors:

Answer 5

Muscles or glands that react to the motor stimulus to bring about a change in response to a stimulus.

Question 6

Feedback systems:

Answer 6

• Negative feedback systems (most common)
• Positive feedback systems

Question 7

Negative feedback systems:

Answer 7

1. Small change in one direction is detected by sensory receptors.
2. Communication system informs effector
3. Effector reacts to reverse change
4. Return to optimum conditions

Works to reverse change

Question 8

Positive feedback systems: examples

Answer 8

• Blood clotting cascade –> Blood vessel damages, platelets stick to damaged region, release factors that initiate clotting, attract more platelets.
• Childbirth (oxytocin) –> Baby head presses against cervix, stimulates production of hormone oxytocin, oxytocin stimulates uterus to contract, contractions push baby head harder against cervix, more oxytocin released.