nervous system Flashcards
what is CNS consist of
brain and spinal cord
what peripheral nervous system
sensory neurones, motor neurones
comparison of nervous system and endocrine system
the nervous system is very rapid and the endocrine system is very slow
in the nervous system, electrical impulses travel along the nerves. in endocrine system, chemical messengers travel by bloodstream
example of nervous system: blinking
example of nervous system: growth
what is the end of neurone called and its purpose
synapse. a tiny gap between nerve cells, the impulse only can travel this gap in one direction
how do impulse travel across synapse
impulse arrives
there are neurotransmitters at the endplate
the chemical is released into the gap
the chemical diffuses across the gap and the impulse restarts on the other side
feature of motor neurone
dendrites- collect information from other cells
axon- a long fibre which carries information away from the cell body, over long distances
fatty sheath made of myelin- gives electrical insulation between neighbouring cells and makes impulses travel faster
which feature do relay neurone don’t have compared to a motor and sensory neurone
fatty sheath
describe reflex action
receptor receive stimulus and convert it into electric impulse
sensory neurone carries the impulse to CNS
relay neurone carries impulse slowly across spinal cord, carry impulse from the brain
the motor neurone carries impulse from the CNS to effector
effector carries out an action
what is a reflex action
rapid automatic response to a stimulus. all reflex actions have evolved to help us survive. a reflex is an involuntary action
what is a voluntary action
a conscious decision is involved for voluntary actions
actions need to be learnt
slower than involuntary actions
what is an involuntary action
reflexes
no conscious decision though the person is aware
rapid
same stimulus results in the same response
what is sense organs
a group of receptor cells responding to specific stimulo
example of stimuli
light, sound, touch, temperature
what is fovea
the area has the highest density of cones so offers maximum sharpness
another term for exit point of the optic nerve
blind spot
what is cornea
a transparent layer for refraction of light rays that enters the eye
the feature of the image formed on the retina
inverted and diminished
the process of the brain correcting the inversion and reduction in the size of the image
integration
what happens to the suspensory ligaments and ciliary muscle when looking at a distant object
ciliary muscle relax, eyeball becomes spherical
ligaments become tight
because light needs to be refracted less so the lens needs to be long and thin
what happens to the suspensory ligaments and ciliary muscle when looking at a closed object
ciliary muscles contract, pull eyeball inwards
ligaments relax
because light needs to be refracted more so the lens becomes short and fat
what happens to the pupil when light intensity decreases
radical muscles of the iris contract
circular muscle relax
what happens to the pupil when light intensity increases
circular muscles of the iris contract
radical muscle relax
what is an endocrine system
a series of organs called glands, which secretes chemicals called hormones
where does adrenaline secreted
adrenal glands
