6.3 (16) - Homeostasis Flashcards
What is homeostasis?
The maintaining of a constant internal environment within a living organism
What does homeostasis maintain?
- Blood pH
- Core temperature
- Blood glucose concentration
- Water potential of blood
What systems control homeostasis?
- Nervous system
- Endocrine system
- A combination of both
What are the stages of the feedback loop?
Stimulus -> receptor -> coordinator -> optimum point -> effector
What does stimulus mean, in the context of a feedback loop?
Deviation from the optimum point
What does receptor mean, in the context of a feedback loop?
Detects a change
What does coordinator mean, in the context of a feedback loop?
Coordinates information from receptors and sends instructions
What does effector mean, in the context of a feedback loop?
Brings about the change needed to return the system to its optimum point
What does optimum point mean, in the context of a feedback loop?
Point at which a system operates at its best
What is negative feedback?
When a change in internal conditions is reversed and returned back to the set point in order to maintain optimum point
What is positive feedback?
The change detected is increased further away from the optimum point and does not lead to homeostasis
What is an endotherm?
An organism maintaining its body temperature by physiological mechanisms
What is an ectotherm?
An animal that uses the environment to regulate its body temperature
How do endotherms gain heat?
- Vasoconstriction (blood vessels getting narrower)
- Shivering
- Raised hairs
- Increased metabolic rate
- Decreased sweating
- Behaviour (eg. using a blanket)
How do endotherms lose heat?
- Vasodilation (blood vessels getting wider)
- Increased sweating
- Lowered hair
- Behaviour (eg. having a cold bath)
