B9 Coordination and response - 1 & 2 Flashcards
What is a nerve impulse?
A nerve impulse (information) is an electrical signal that passes along nerve cells called neurones. -
What does the human nervous system consist of?
The human nervous system consists of the:
-central nervous system (CNS) - brain and spinal cord
-peripheral nervous system (PNS) - all of the nerves in our body.
What does the human nervous system allow us to do?
It allows us to:
-Make sense of our surroundings and respond to them.
-Coordinate and regulate body functions.
What is a nerve?
A nerve is a bundle of neurones.
What do nerves do?
Nerves send electrical impulses around the body. They receive information from receptors and send instructions out to effectors.
What is the central nervous system?
The central nervous system is the brain and spinal cord and acts as a coordinator for the rest of the nervous system.
What is the peripheral nervous system?
The peripheral nerve system are the nerves with sensory and motor neurones.
What is a voluntary response?
A voluntary response is one where you make a conscious decision to carry out a particular action therefore it starts with your brain.
-Often take longer as we consider what the consequences might be before doing it.
What is an involuntary (or reflex) response?
An involuntary (or reflex) response does not involve the brain as the coordinator of the reaction and you are not aware you have completed it until after you have carried it out.
-Tend to be rapid and an automatic response to a stimulus.
What are the three main types of neurones?
Sensory, relay
and motor neurones.
What is the function of sensory neurones?
Sensory neurones carry impulses from sense organs to the CNS.
What is the function of relay neurones?
Relay neurones are found inside the CNS and connect sensory and motor neurones.
What is the function of motor neurones?
Motor neurones carry impulses from the CNS to the effectors.
What does a sensory neurone look like?
A sensory neurone is very long and has a cell body branching off in the middle of the axon.
What does a relay neurone look like?
A relay neurone is short and has a small cell body at one end with MANY dendrites bracing off it.
What does a motor neurone look like?
A motor neurone is long and has a large cell body at one end with long dendrites branching off.
Why is a reflex response so rapid?
A reflex response does not involve the brain and is therefore quicker than any other type of nervous response. This helps to minimise the damage to the body.
What is the reflex arc?
The reflex arc is the sequence of neurones that the impulse passes along in order to trigger the reflex response.
What is the reflex arc sequence?
Stimulus => Receptor => Sensory neurone => Relay neurone => Motor neurone => Effector => Response.
What is a reflex action?
A reflex action is a means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors (muscles and glands).
What is the stimulus?
The stimulus is the trigger of the reflex. - touch, light or sound.
What is the receptor?
The receptors are a group of specialised cells that detect a change in the environment and stimulate electrical impulses in response. Once the receptor cell in the sense organ has been stimulated, it generates an electrical impulse which is passed on to a sensory neurone and so on.
What is the effector?
The effector is what carries out the response. It may be a muscle or gland.
What is the eye?
The eye is a sense organ containing receptor cells that are sensitive to light (rod) and colour (cone).
