topic 8 Flashcards
(32 cards)
what is a stimulus
any change in the internal or external environment
what is a receptor
they detect stimuli
what’s an effector
produce responses to stimuli
what is the nervous system
send information as electric impulses, made of a complex network of neurones
what are the three types of neurones
sensory, motor, relay
what do sensory neurones do
transmit electrical signals from receptors to the CNS
what do motor neurones do
transmit electrical impulses from the CNS to the effector
what do relay neurones do
transmit electrical signals between sensory and motor neurones
how are the nervous and hormonal system different
hormonal- chemical, slow, widespread response
nervous- electrical impulses, fast, localised response
what are photoreceptors and where are they located
in the eye, they are receptors that react to visual stimuli
how do photoreceptors convert light energy into an electric impulse
light enters the eye, hits the photoreceptor and is absorbed by light-sensitive pigments
light bleaches the pigments causing a chemical change, triggering a move impulse along the bipolar nerve
name the two types of photoreceptor
rod cell, cone cells
what do rod cells do and where are they located
found in the peripheral parts of the retina, only give information in black and white (monochromatic vision)
what do cone cells do and where are they located
they are packed together in the fovea, they give information in colour (trichromatic vision)
what are the three types of cone cells
red sensitive, blue sensitive, green sensitive
what do rod cells when stimulated by light
hyperpolarise
what pigment do rod cell contain and what is it made up of
rhodopsin- made of two chemicals joined together- retinal and opsin
what happened when its dark
rod cells aren’t stimulated-
sodium ions are pumped out of the cell, diffuses back into the cells through the open channel, this makes the cell slightly negative depolarising it, this releases neurotransmitters, the neurotransmitters inhibit the bipolar neurone, no action potential
what happens when its light
rod cells are stimulated-
light breaks apart rhodopsin, this causes the sodium channel to close, sodium ions leave the cell, but can’t diffuse back in, the cell is more negative on the outside making it hyperpolarised, this stops neurotransmitters being released, meaning there’s no inhibition of the bipolar, action potential
what is the structure and function of a motor neurone
many short dendrites carry impulses from CNS to cell body, one long axon carries impulses from cell body to effector cells
what is the structure and function of a sensory neurone
on long dendron carries impulse from receptor cells to cell body which is located in the centre of the cell, on short axon carries nerve impulses from cell body to CNS
what is the structure and function of a relay neurone
many short dendrites carries impulse from sensory neurone to cell body, an axon carries impulse from cell body to motor neurone
name the steps of stimulation.
stimulus, depolarisation, depolarisation, hyper polarisation, resting potential
what happens when a stimulus is detected
this excites the neurone cell membrane causing sodium ion channels to open. the membrane becomes more permeable to sodium, so sodium ions diffuse into the neurone. making the inside of the neurone less negative
