Chapter 6: Coordination Flashcards
What is the role of a receptor?
To detect a stimulus by changing its energy into the electrical energy of the nerve impulses
What is transduction?
When energy is changed from one form into another receptor type of energy transduced
eye -> light
ear -> sound, movement
tongue, nose -> chemical in food / air
skin -> movement, heat
muscle -> movement
What is the Central Nervous System
An animal’s response to a stimulus is coordinated by its central nervous system (CNS).
The CNS consists of the brain and the spinal cord.
It gathers information about, and responds to, changes in the environment.
What is the CNS sequence?
The CNS coordinates the information and sends impulses along motor neurons to the effectors, which bring about a response.
The sequence is as follows:
- Stimulus -> 2. Receptor -> 3. Sensory neuron -> 4. Central nervous system -> 5. Motor neuron -> 6. Effector -> 7. Response
What are neurones?
Neurones are nerve cells. They carry information as tiny electrical signals. There are three types of neurones:
Sensory neurones: carry signals from receptors to the spinal cord and brain.
Relay neurones: carry messages from one part of the CNS to another.
Motor neurones: carry signals from the CNS to effectors. See image
Describe the structure of motor and sensory neurones…
The cell body is at one end of the fibre (has dendrons)
The long fibres that carry the impulses to the effector organ is call the axon (which is covered by a sheath of fatty material called myelin to prevent short-circuits with other axons)
At the end of the axon it divides into many nerve endings out to muscle…causing muscle fibres to contract
What is the sclera?
The tough outer coat of the eye
What is the cornea?
The transparent ‘window’ at the front of the eye which lets light into the eye
It is convex and transparent.
It refracts light - bends it as it enters the eye
What is the iris?
Its muscles contract and relax to alter the size of its central hole or pupil.
It controls how much light enters the pupil
What is the lens?
Transparent, bi-convex, flexible disc behind the iris attached by the suspensory ligaments to the ciliary muscles.
It focuses light onto the retina
What is the retina?
The lining of the back of eye containing two types of photoreceptor cells - rods - sensitive to dim light and black and white - and cones - sensitive to colour.
A small area called the fovea in the middle of the retina has many more cones than rods.
It contains the light receptors
What is the optic nerve?
A bundle of sensory neurones at back of eye.
Carries impulses from the eye to the brain
What is the choroid?
A dark layer under the sclera…stops light being reflected around inside the eye
Located the main parts of the eye on this diagram…
How is an image formed on the retina and what is refraction?
To form an image on the retina…light needs to be bent or refracted.
Refraction takes place when l_ight passes from one medium to another of a different density_
As a result of refraction…the image on the retina is upside down or inverted
What is a synapse and how do they work?
A synapse is the gap between two nerve cells.
- An electrical impulse travels along an axon.
- This triggers the nerve-ending of a neuron to release chemical messengers called neurotransmitters.
- These chemicals diffuse across the synapse (the gap) and bind with receptor molecules on the membrane of the next neuron.
- The receptor molecules on the second neuron bind only to the specific chemicals released from the first neuron. This stimulates the second neuron to transmit the electrical impulse.
What are the four main areas of the brain?
1. the cerebrum which controls memory, personality and conscious thought
2. the cerebellum which controls balance and co-ordination of movement
3. the medulla which controls heart rate and breathing rate
4. the hypothalamus which is the regulating centre for temperature and water balance
Can you idenitfy the different parts of the brain on this diagram?
