The Nervous System Flashcards
What are receptors?
cells that detect changes in the internal or external environment
What are coordination centres?
areas that. receive and process the information from the receptors. They send out signals and coordinate the response of the body e.g. brain spinal cord and pancreas
What are effectors?
Muscles or glands that bring about responses to the stimulus
What is the nervous system made up of?
sensory neurones - carry impulses from receptors to. CNS
CNS - Central nervous system - Brain and spinal cord
motor neurones - carry impulses from CNS to effectors
What is a reflex?
rapid automatic responses to certain stimuli that don’t involve the conscious part of the brain
What is a synapse?
Connection between two neurones
nerve signal is transferred by chemicals
What is the reflex arc?
stimulus detected by a receptor – sensory neurone – relay neurone –motor neurone – effector
What is reaction time?
how quickly you respond
How to measure reaction time?
Drop ruler test - catch a ruler as quickly as possible that is dropped from above you - number on ruler = reaction time. Lower number = quicker time
Computer eg clicking mouse when image shown on screen
What is the structure of the brain?
Billions of interconnected neurones
Formed of the cerebral cortex, medulla, cerebellum
What is the cerebral cortex?
The outer bit - in control of consciousness, intelligence, memory and language
What is the medulla?
Controls unconscious activities e.g. breathing, heartbeat, temperature
What is the cerebellum?
Responsible fro muscle coordination
What is the spinal cord?
A continuation of the brain to form the rest of the CNS
How to study the brain?
Watching
Electrical stimulation
MRI
Structure of the eye?
Sclera, cornea, iris, pupil, lens, retina
,What is the sclera?
Tough, supporting wall of the eye - the whites of your eyes
What is the cornea?
Transparent outer layer of the front of the eye, refracts light into the eye
What is the iris?
Coloured part of the eye
Contains muscles that control the size of the pupil
The pupil is the hole in the middle of the iris
What is the lens?
Focusses light onto the retina
What controls the shape of the lens?
Ciliary muscles and suspensory ligaments
What is the retina?
Contains receptor cells sensitive to light intensity and colour
What does the optic nerve do?
Transmit impulses from the receptors on the retina to the brain
What is the iris reflex?
Very bright light – detected by receptors – reflex triggered – circular muscles in iris contract – smaller pupil
What is accommodation?
When the eye focusses light on the retina by changing the shape of the lens
How to focus on near objects?
Ciliary muscles tighten
Suspensory muscles relax
How to focus on far objects?
Ciliary muscles relax
Suspensory muscles tighten
Long sighted?
Unable to focus on near objects
Lens is wrong shape - does not refract light enough
Eyeball is too short
Glasses with convex lens
Short sighted?
Unable to focus of distant objects
Lens is wrong shape - refracts light too much
Eyeball too long
Glasses with concave lens
Treatments for vision defects?
Contact lenses
Laser eye surgery
Replacement lens surgery
