Topic 6- Reflex arcs and neurons Flashcards
What are the 3 types of neurones?
-Sensory
-Relay
-Motor
What is the function of sensory neurons?
-carry impulses from receptors to the Central Nervous System (CNS - the brain or spinal cord)
What is the function of relay neurones?
connect sensory and motor neurones
Where are relay neurones found?
Within the CNS
What is the function of motor neurons?
Carry impulses from the CNS to effectors (muscles or glands)
What do all 3 types of neurons work together to do?
-To bring about a response to a stimulus
What is a reflex arc?
-A pathway where impuleses are transmitted from a recpetor to an effector
-Without the involvement of concious regions in the brain
Why are other types of nervous responses not as quick as reflex responses?
-As they involve the brain
Give some examples of reflex actions involving the eye
-Blinking
-Focusing the eye on an object
-Controlling how much light enters the eye
Explain how sensory neurones, intermediate (relay) neurones and motor neurones work together to carry out a reflex action?- use the example of somebody stepping on a pin
1.Stimulus
-Person steps on the pin
-Pin= stimulus
2.Receptor
-Stimulus is detected by a pain receptor in the skin
3.Sensory neuron
-sensory neurone sends electrical impulses to the spinal cord (the coordinator)
4.Relay neurone
-Electrical impulses are passed on to relay neurone in the spinal cord
-Relay neurone connects to the motor neurone and passes the impulses on
5.Motor neuron + effector
- carries the impulses to the muscle in the leg (the effector)
6.Response
-impulses cause the muscle to contract and pull the leg up and away from the sharp objec
Why are reflexes useful?
-Protect the body from damage
-May allow an animal to avoid being caught by a predator
Are reflexes involved in balance?
Yes
What are nerve impulses
electrical signals that pass along nerve cells known as neurones
What is nerve?
A bundle of neurones is known as a nerve
What do neurons coordinate?
activities of sensory receptors, decision-making centres in the central nervous system, and effectors such as muscles and glands
What does the presence of schwann cells mean?
The electrical impulse does not travel down the whole axon but jumps from one node to the next
What is saltatory conduction?
‘jumping’ of the electrical impulse between nodes of Ranvier
why is saltatory conduction useful?
speeds up the conduction of the impulse and its transfer from one cell to another
