Nerves And Sensitivity Flashcards
What are the three things that a coordinated response requires ?
A stimulus , a receptor and an effector
What is a stimulus?
Change in the animals surrounding
What is a receptor?
The organ which detects the change
What is an effector ?
Muscles that move
What happens when receptors detect a stimulus ?
Receptor changes its energy into nerve impulses
What are the two types of nervous system ?
- Central nervous system
* peripheral nervous system
What is the central nervous system made up of ? And what does it do ?
Brain and spinal cord
And coordinates all the nervous responses like moving or reflexes
What is the peripheral nervous system made up of?
And what does it do ?
Nerves and it sends impulses to all the effectors
What are nerve cells ?
And give examples of some ?
neurones,
And skin and muscles are examples of them
What are the three types of neurone ?
- sensory neurone
- relay neurone
- Motor neurone
What neurone do impulses from receptors pass along ?
Sensory neurone
What neurone do you impulses from the CNS pass along ?
Relay neurone
What neurone do impulses to effectors pass along ?
Motor neurone
Why is your response to a stimulus quicker by sight then touch ?
- Optic nerve to the brain/CNS is closer than the fingers to the brain
- not as many synapses to pass across
- synapses slow impulses down as neurotransmitters need to diffuse across the synapse
What is a dendrite ?
Tree like projections which connect to different neurons
What is the cell body of a neurone ?
The main section of the cell, containing the nucleus
What is the axon ?
The long section in which the signal is sent
What is the myelin sheath ?
The insulating layer
What are reflexes ?
Are automated actions which do not involve the brain. They are very fast actions which involve the three neurones
What is the movement of the impulse from receptor to effector called ?
Reflex arc
Order of the reflex arc
- The receptors detect stimulus change and send an impulse along a sensory neurone
- The sensory neuron passes the impulse across the spinal cord to a relay neurone , the gap between neurones are called a synapse. The relay neurone then passes the impulse to a motor neuron
- The motor neuron causes the factor to contract and move the body put away from the stimulus
Order of the synapse
- and impulse travels along the sensory neurone until it reaches a synapse
- The impulse triggers the release of chemical transmitters called neurotransmitters, which diffuse across the synapse
- The neurotransmitters are complimentary to receptors on the other neurone and bind to the surface
- A new impulse travels along the relay neurone
What sort of organ is the eye ?
A sensory organ
What does the brain do to the impulse that is sent from the eye ?
Convert that information into an image which is what we “see”
What is the cornea
Are curved transparent disk at the front of the eye. Does most of the focusing.
What is the pupil ?
A circular opening who size is controlled by the iris
What is the iris ?
Ring of muscle with a hole in the middle called the pupil . The iris controls how much light enters the eye
What is the lens ?
This is soft, flexible and transparent. Its shape can be changed to find tune the focusing of light on the retina
What is the ciliary muscles ?
Ring of muscle at the edge of the eye which circles the lines. When it contracts the lens gets fatter. When it relaxes the lens gets thinner
What is the suspensory ligament ?
Strong fibres which attach the lens to the ciliary muscle
What is the retina?
Contains light sensitive cells called rods and cones
What is the optic nerve?
Consisting of many neurones which carry impulses from the retina to the brain
What is the fovea ?
The region of the retina with the greatest number of cones
What is conjunctiva ?
Mucous membrane that covers the eye to prevent infection
What happens to your eye in dim light ?
Pupil dialation
• radial muscles contract
• circular muscles relax
What happens to your eye in bright light ?
Pupil contraction
• radial muscles relax
• circular muscles contract
What is the anagram to help remember what happens to your eye in different lights ?
Pupil contraction , circular , contract
What is the name given to describe the ability of the eye to focus on near and far objects ?
Accommodation
What happens to the eye when a object is far away ?
- Ciliary muscles relax
- this makes the suspensory ligaments tight
- making the lens long and thin
- meaning less convex
- refracting less light
What happens to the eye when object is close ?
- ciliary muscles contract
- making the suspensory ligaments relax
- making the lens short and fat
- and more convex
- refracting more light
What is the anagram to remember what happens to the eye when objects are close and far away ?
Close, ciliary contract, more convex
What happens in short-sighted people ?
- light focuses short of the retina
- it is corrected by using a diverging lens
- short-sighted people can’t see objects far away
What happens in long-sighted people ?
- light focuses long of the retina
- it is corrected using a converging lens
- long-sighted people cannot focus on close objects very well
What is a blind spot ?
What your optic nerve is and there are no rights or cones on the optic nerve, so you cannot see anything there .
