Co-ordination and Control

Co-ordination of what happens inside your body, and responses to changes outside your body, rely on hormones and the nervous system.

The nervous system involves neurones and impulses, which are electrical (but chemical at a synapse.)

A reflex is a rapid, automatic response to a stimulus.

Hormones are chemicals produced by glands and carried in your blood stream.

STEPS IN A REFLEX ACTION:

• A receptor detects the stimulus.
• A sensory neurone transmits the impulse.
• A relay neurone passes the impulse on.
• A motor neurone is then stimulated, passing the impulse to the effector.
• The effector is a gland or a muscle.
• Action is taken.

Reflex actions are responses that are RAPID and AUTOMATIC.They do not involve the brain.

The menstural cycle is controlled by three hormones:

• Follicle stimulating hormone
• Oestrogen
• Lutenising…