B10 - The Nervous System Flashcards
what is homostasis
It is the regulation of internal conditions of a cell or organism to maintain optimum conditions for the function
what are receptors
They are cells that detect changes in the external and the internal environment
What are effectors
They are cells that bring about a change
e.g. muscles, glands
What internal conditions are controlled
Blood sugar level
Temperature
What are coordination centres
They are places where information is received and processed from receptors and organises the response
e.g. Brain, Spinal cord, Pancreas
What is a stimuli
It is a change in the environment
What stimuli do eyes detect
Light
What stimuli do Ears detect
Sound and change in position (Help us keep our balance)
What stimuli does Tongue and Nose detect
Chemicals
What stimuli does skin detect
Touch, pressure, pain and temperature changes
What order happens for a reaction
Stimulus > receptor > Coordinator > Effector > Response
What do motor neurons do
They transmit impulses from the CNS to the effector
What is the CNS
Central Nervous System
It is a coordination centre where responses are made
What do sensory neurons do
They transmit impulses from the receptors to the CNS
What are reflexes
They are actions which are automatic and rapid and do not involve the conscious part of the brain
what are synapses
They are gaps between neurons
What happens at synapses
When the impulse arrives at the synapse, chemicals are released that diffuse across the gap and then bind to the receptor sites
What are glands
They are organs which secrete substances such as hormones
what are hormones
They are chemical messages
What does the brain control
It controls complex behaviour
What is the brain made of
It is made of billions of interconnected neurons and has different regions that carry out different functions
What function does the cerebral cortex carry out
It carries out consciousness, intelligence, memory and language
What function does the cerebellum carry out
It carries out coordination of muscular activity
What function does the medulla carry out
It carries out unconscious activities like breathing and heartbeat
How is the brain studied
Studying behaviour of people with brain damage, Electrically stimulating the brain and MRI scans
What is the function of the sclera
The tough, white outer layer prevents damage to the eye
What is the function of the cornea
The transparent area at the front of the sclera
What is the function of the Iris
Has sets of muscles that control the size of the pupil and regulate the light reaching the retina
What is the function of the pupil
The hole in the centre of the iris that allows light to pass through
What is the function of the lens
Focuses the light rays on the retina
What are the functions of the suspensory ligaments and the ciliary muscles
Change the shape of the lens to focus the light rays on the retina
What is the function of the retina
Made up of light sensitive receptor cells
What is the function of the optic nerve
Carries impulses from the retina to the brain
What happens to the eyes in bright light
Circular muscles contract
Radial muscles relax
Pupil constricts
What happens to the eyes in dim light
Circular muscles relax
Radial muscles contract
Pupil dilates
What is accommodation
The process of changing the shape of the lens to focus on near or distant objects
What happens when the eyes focus on nearby objects
The ciliary muscles contract
The suspensory ligaments loosen
The lens is thicker so refracts light rays strongly
What happens when the eyes focus on distant objects
The ciliary muscles relax
The suspensory ligaments tighten
The lens is thinner and only slightly refracts light rays
What is myopia
Short sightedness where people cant focus on distant objects
Lens is to long
what is hyperopia
Long sightedness where people cant focus on close objects
Lens is to short
How can myopia be fixed
Concave lens
How can hyperopia be fixed
Convex lens
How can vision be corrected
Contact lenses - Increases the risk of eye infection
Laser eye surgery - Risk of infection and vision could get worse
Replacement lens surgery - High risk and possible damage to retina
