Homeostasis - Intro and Feedback Mechanisms

Question 1

What is homeostasis?

Answer 1

The process by which internal physical + chemical conditions are kept within a range suitable for life processes

Question 2

What are the 3 components of a homeostatic control system?

Answer 2

1. Sensor (receptor): detects change in a variable
2. Control centre: receives message from receptor, directs response via effector
3. Effector: carries out response

Question 3

What are the variables that must be regulated to maintain homeostasis?

Answer 3

• Body temp
• pH
• Water levels
• Oxygen/CO2 levels
• Nutrient levels (blood glucose, vitamins, minerals)
• Electrolytes
• Conc. of wastes, toxins, etc.

Question 4

What is negative feedback?

Answer 4

• System that brings body systems back to acceptable levels
• Decreases effects of stimulus
• Example: light shining in eyes: iris causes pupils to constrict (decrease in pupil size = decrease of light stimulus)

Question 5

What is positive feedback?

Answer 5

• System that brings body systems further from natural state
• Increases effects of stimulus
• Example: childbirth: baby’s head pushes against cervix -> cervix sends message to brain -> brain releases oxytocin -> oxytocin stimulates uterine contraction -> pushes baby’s head further into opening