Principles of Homeostasis

What is homeostasis?

The maintenance of a constant internal environment

What are the internal conditions within our bodies?

• Blood glucose levels
• Water levels
• Temperature
• pH of blood
• Oxygen
• Mineral ions (must be kept at optimal point)

Why do we need to control the internal conditions in our bodies?

1) Enzymes control the rate of reactions

What are the bodies control mechanisms?

• Receptors
• Coordination centres
• Effectors

What are the receptors?

Detect the stimulus or change in environment.

What are the coordination centres?

Areas (brain

What do the effectors do?

Respond to the stimulus to return internal conditions back to normal

What are examples of effectors?

Muscles and glands

How do we detect changes and respond to them?

Nerve and hormonal responses

How does the nervous system respond to changes?

They are send very fast and precise electrical impulses through the nerves = responds quickly

How does the hormone response respond to changes?

They travel in the blood

What is the nervous response?

Stimulus -> Receptor -> Central Nervous System -> Effector -> Response

If the receptor is the ear

what is the stimulus?

If the receptor is the eyes

what is the stimulus?

If the receptor is the nose

what is the stimulus?

If the receptor is the tongue

what is the stimulus?

If the receptor is the skin

what is the stimulus?

You have just heard a noise in the next room. You decide to go and investigate. Describe your nervous response.

The stimulus is the sound vibrations. This is detected by the ear cells (receptor) which pass an impulse along the sensory neurone to the central nervous system (brain) The brain decides to walk into the next room. It sends an impulse along the motor neurone to the effector which is the muscles in the legs. The response is the person walks to the next room.