the human nervous system (required practical) Flashcards
what does the CNS contain?
the brain and spine.
what are motor neurones?
neurones that carry impulses from the CNS to effectors.
what are sensory neurones?
neurones that carry impulses from receptors to the CNS.
what are effectors?
muscles and glands. (which responds to impulses and bring a change)
what are receptors?
cells that detect stimuli.
what does the CNS do?
it receives information from the receptors and coordinates a response for the effectors.
what are synapses?
the connection between two neurones
what are reflexes?
quick automatic responses that don’t involve the conscious part of your brain.
what is reaction time?
how long it takes to respond to a stimulus.
how can you measure the effect of caffeine on reaction time? (practical)
- a person should sit with their arm resting on the edge of a table.
- hold a ruler between their thumb and finger. (zero is level with the thumb)
- randomly drop the ruler and the person has to catch it as quick as possible.
- the reaction time is measured with the number on the rule. (lower is better)
- repeat the test multiple times for a mean.
- consume a caffeinated drink and wait 10 minutes, repeat the test.
compare the results.
what is the cerebral cortex responsible for?
consciousness, intelligence, memory, language.
what is the medulla responsible for?
unconscious activities. (like breathing or heartbeat)
how can the brain be studied? (3)
- observing patients with brain damage. (to see what they do different)
- electrically stimulating the brain. (to see what happens)
- MRI scans. (when responding to stimulus)
what is the cerebellum responsible for?
muscle coordination.
what is the sclera?
what is the cornea?
what is the iris?
what is the lens?
what is the optic nerve?
what are ciliary and suspensory ligaments?
what is the retina?
sclera - tough supporting wall of the eye.
cornea - transparent outer layer at the front of they eye that refracts light.
iris - contains muscles to control the diameter of the pupil. (how much light comes in)
lens - focusses light into the retina.
optic nerve - carries impulses from receptors in the retina to the brain.
ciliary and suspensory ligaments - controls the shape of the lens.
retina - contains receptor cells for light intensity and colour.
how does the eye respond to changes in light?
bright light - circular muscles contract and radial muscles relax.
dim light - circular muscles relax and radial muscles contract.
how does the eye respond to focus on objects at a distance?
near objects - ciliary muscles contract slackening suspensory ligaments. (lens is fat and refracts more)
far objects - ciliary muscles relax tightening suspensory ligaments. (lens is thin and refracts less)
what is long and short sighted?
long sighted - the lens isn’t round enough or the eyeball is too short. (light doesn’t refract enough and focusses behind the retina)
short sighted - the lens is too round or the eyeball is too long. (light refracts too much and focuses in front of the retina)
what are the treatments for eye defects?
contact lenses.
laser eye surgery.
replacement lens surgery.
