11 CO-ORDINATION + CONTROL Flashcards
Define homeostasis
The maintenance of a constant internal enviroment
What is needed for a coordinated response
Stimulus, receptor, effector
What is in the central nervous system
The brain and spinal cord
How is the CNS linked to sense organs
Neurones
Types of neurone
- Sensory
- Relay
- Motor
How do the 3 types of neurones interlink
- Impulse from receptor pass along sensory neurones until they reach the CNS
- Impulses pass to relay neurones in the CNS
- Impulse passed to effectors along motor neurones
Role of myelin sheath
Insulates axon and speeds up transmission of impulse
Why are reflexes rapid
They do not involve the brain
Describe the process of a reflex arc
- Receptors detect the stimulus
- Send an electrical impulse along the sensory neurone
- Sensory neurone passes impulse to spinal cord to a relay neurone
- By neurotransmitters across the synapse
- Relay neurone passes the impulse through the spinal cord to a motor neurone
- Motor neurone causes effector to move away from stimulus
Describe what happens at the synapse
- Electrical impulse travels along axon
- Triggers neurotransmitters to be released and to diffuse across synapse
- Bind with receptor molecules on second neurone
- Stimulates another electrical impulse
Function of cornea
Focuses objects on the front of the eye
Function of pupil
Circular opening that’s controlled by the iris
Function of iris
Controls how much light enters pupil
Function of ciliary muscles
Contracts = lens gets thicker, relaxes = lens gets thinner
Function of suspensory ligament
Attach to ciliary muscle
Function of lens
Focuses light onto retina
Function of retina
Contains rods and cones