Flashcards in ch-13 Coordination and response Deck (34)
What is nerve impulse?
nerve impulse is an electrical signal that passes along nerve cells called neurones.
What does human nervous system consists of?
central nervous system (CNS) – the brain and the spinal cord
peripheral nervous system (PNS) – all of the nerves in the body
Name three main types of neurones and their functions.
Sensory neurones carry impulses from sense organs to the CNS (brain or spinal cord)
Relay neurones are found inside the CNS and connect sensory and motor neurones
Motor neurones carry impulses from the CNS to effectors (muscles or glands)
Brief 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
Brief Involuntary Responses
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
Involuntary actions are usually ones which are essential to basic survival and are rapid, whereas voluntary responses often take longer as we consider what the response might be before doing it
What is Synapse?
The junction between two neurones is known as a synapse
Write the reflex pathway.
What is a bundle of neurones known as?
What are the two main communication systems inside an animals body?
Give two examples of effectors.
name the nerve cell that transmits impulses from the CNS to an effector
Name the part of the eye that refracts light rays most strongly
Name the part of the eye that contains receptor cells
Name the gap between two neurones
Name the action of the ciliary muscle when the eye is focusing on a nearby object
Name the cells that are sensitive to different colors of the light
What is a reflex arc?
The pathway along which the nerve impulse passes is called a reflex arc.
What is reflex action?
reflex action is a means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors (muscles and glands).
How an Impulse is Passed Across a Synapse
The electrical impulse travels along the first axon
This triggers the nerve-ending of the presynaptic neurone to release chemical messengers called neurotransmitters from vesicles which fuse with the presynaptic membrane
The neurotransmitters diffuse across the synaptic gap and bind with receptor molecules on the membrane of the second neurone (known as the post synaptic membrane)
This stimulates the second neurone to generate an electrical impulse that travels down the second axon
The neurotransmitters are then destroyed to prevent continued stimulation of the second neurone which would cause repeated impulses to be sent
Synapses ensure that impulses only travel in one direction, avoiding confusion within the nervous system if impulses were travelling in both directions
Where does drugs like heroin affect?
synapse is the only part of the nervous system where messages are chemical as opposed to electrical, it is the only place where drugs can act to affect the nervous system
Define sense organs
Sense organs contain groups of receptors that respond to specific stimuli
What is the function of cornea?
What is the function of iris?
controls how much light enters the pupil
What is the function of lens?
focuses light onto retina
What is the function of retina ?
contains light receptor cells- some sensitive to
light of different colours
What is the function of optic nerve ?
carries impulses to the between the eye and the brain
What is the function of pupil ?
hole that allows the light to enter the eye
How does the Pupil Reflex Work in DIM light?
1. photoreceptors detects the change in the environment - DARK
2. RADIAL MUSCLES CONTRACT
3. CIRCULAR MUSCLES RELAX
4. PUPIL DILATES
5. MORE LIGHT ENTERS THE EYE
How does the Pupil Reflex Work in BRIGHT light?
1. photoreceptors detects the change in the environment - BRIGHT
2. RADIAL MUSCLES RELAX
3. CIRCULAR MUSCLES CONTRACT
4. PUPIL CONSTRICTS
5. LESS LIGHT ENTERS THE EYE