Co-ordination And Control Flashcards
What is a stimulus?
Anything that we respond to/triggers an impulse
What does an effector affect?
A receptor
What happens when a receptor is stimulated?
It causes an effector to produce a response
What are receptors and effectors connected by?
A coordinator, usually the brain but may also be the spinal cord
(CNS)
What are the brain and spinal cord known as?
The central nervous system
What links the receptors and effectors to the coordinators?
Nerve cells or neurones
What do neurones carry information as?
Small electrical charges called nerve impulses
How are neurones adapted? (4)
– They have a nucleus that controls the activities of the neurone
– They have long axons so that nerve impulses can be carried across long distances throughout the body
– They have a fatty layer called the myelin sheath that acts as an insulator that helps to speed up the nerve impulses
– The branched ends of the axon allow the neurone to make junctions with other nerve cells
What is a synapse?
The junction between two neurones
How are nerve impulses transferred from one neurone to another?
- When an electrical impulse reaches the end of the axon, it causes the axon to release a special chemical called the transmitter substance (neurotransmitter) which diffuses across the gap.
- If the concentration of transmitter substance is high enough on the other side of the synapse, it triggers an electrical impulse on the axon leaving the junction and the nerve impulse continues on its way
What is a voluntary action?
An action we do deliberately that involves conscious thought
What is a reflex action?
An action that does not involve conscious thought that happens automatically, like breathing or blinking
What are the two main characteristics of a reflex action?
- They occur very rapidly
and - do not involve conscious control
What makes reflex actions so rapid?
In a reflex pathway, the length of the pathway is kept as short as possible with the minimum number of neurones needed and as few synapses as possible
What is a reflex arc?
The nerve pathway involved in a reflex action
What is the sensory neurone?
The neurone that carries information from receptors
What is the motor neurone?
The neurone that carries information from the spinal cord back to the effector, causing a response
What is the association / connector / relay neurone?
The neurone that connects the sensory and motor neurone
What does the iris do?
Controls how much light enters the eye
What is the pupil?
The space in the iris through which light passes
What is the cornea?
The transparent front part of the eye that allows light to enter the eye and causes some refraction
What is the aqueous humour?
The transparent, incompressible watery liquid that helps focussing and to maintain the eye’s shape