B5

Question 1

Homeostasis

Answer 1

The regulation of the internal conditions of a cell or organism to maintain optimum (best/ideal) conditions for function in response to internal and external changes.

Question 2

What needs to be kept constant in a cell/in an organism?

Answer 2

Temperature
Blood sugar
CO2 levels
Water levels
PH

Question 3

How does the body detect the changes and then respond to them?

Answer 3

Stimuli: Changes in the environment.

Receptors: Cells that detect change in internal or external environment.

Coordination centre: The areas that receive and process information from receptors.

Effectors: Muscles or glands that bring account a response to the stimulus. (Contraction)

Question 4

The nervous system

Answer 4

The CNS (Central nervous system) is made up of your Brain and your Spinal Cord.

The nervous system works by electrical impulses.

(Echalk practical to test reaction times)

Question 5

Reflex Actions

Answer 5

Reflex actions prevent harm to the body by responding rapidly to stimuli (change in the surroundings. This happens AUTOMATICALLY-the person doesn’t need to think about it.

The route of the reflex response is:

Receptor—Sensory Neurone—Spinal Cord—Motor Neurone—Effector

E.g.  Blinking 
          Sneezing 
          Coughing 
          Eye watering
          Knee jerks

Question 6

Synapse

Answer 6

Where two neurones meet, there is a tiny gap called a synapse. Signals cross this gap wing chemicals released by a neurone. The chemical diffuses across the gap which makes the next neurone transmit an electrical signal.