1. Homeostasis

Success Criteria

Your learning has been successful if you can do the following:

I can define homeostasis.
I can give examples of different homeostatic controls in the body.
I can describe the general components of a homeostatic control system.

Vocabulary

Learn these so you can communicate this concept well.

Larynx (voice box): Helps to create different sounds when we speak.

Hei Mahi (Do Now)

Do Now in your OneNote/Notebook:

The pictures to the right are all related to homeostasis. Write down what you think homeostasis means.

Exit Task

In your Learning Journal:

Re-write this interpreting question so it is asking about Homeostasis:

What does this remind you of...?

Then, write an answer for it.

What is Homeostasis?

Homo = same, Stasis = to remain still or steady

HOMEOSTASIS is the regulation of conditions inside the body to maintain a constant internal environment despite fluctuations in the external environment.

Humans have homeostatic control systems that regulate:

Body temperature
Blood pressure
Level of blood glucose
Levels and balance of respiratory gases in tissues.

What are the Parts of a Homoeostatic Control System?

Homeostatic control systems have 3 functional components:

A RECEPTOR - located in various organs (e.g. skin, eyes, brain) to detect change / a stimulus
A CONTROL CENTRE - located in brain to compare this change against the set point, and give out instructions to effectors.
An EFFECTOR - various organs to direct the appropriate response to correct the change.

Communication systems are vital in ensuring instructions from the control centre are relayed to various effector organs.

There are two communication systems involved:

Nervous system
- Sends very fast and precise electrical signals through nerves
Endocrine system
- Sends slow, long lasting hormonal signals that are sent everywhere in the body.

What is the Mechanism of a Homeostatic Control System?

The mechanism for homeostasis is called NEGATIVE FEEDBACK LOOP.

The response of a homeostatic control system actively opposes or dampens any changes to the environment so as to maintain a stable, constant internal environment. In other words, a negative feedback loop acts as a regulatory mechanism that helps to keep a system in balance by opposing any changes to the system's input.