coordination and control - nervous system - eye - brain- hormones (human+plant) Flashcards
nervous system function
allows communication
CNS - central nervous system
- brain + spinal chord
- revives /processes info - gives out instructions
PNS - peripheral nervous system
- neurones, receptor cells, effectors
- collects info then sends to CNS - acts on instructions from CNS
neurones
- special nervous cells
- motor - sensory - relay
- carry electrical impulses round the body
adaptions of neurones
- long
- myelin sheath - insulates impulses
- numerous dendrites - connections to many neurones
sequence of events
- stimulus - receptor - coordinator - effector - response
sequence of neurones
receptor - sensory - relay - motor - effector
sensory neurones
receptor - sensory - relay (CNS)
dendrites - cell body in middle - receptors
relay neurone
sensory - relay - motor
round with dendrites
motor neurone
relay (CNS) - motor - muscles / glands
cell body - long bit - dendrites
flow of impulse
to dendrites
synapse
GAP BETWEEN NEURONES
- end of cell (electrical- chemical message)
- chemical transmitter molecules carry across synapse
- binds to receptor - open channels
- initiates new nerve impulse
(transmitter taken back to presynaptic neurone)
reflex arc
subconscious response to dangerous stimuli extremely quick (not involve brain)
survival instinct
sight
eye
light
hearing
ear
sound
smell
nose
chemicals in the air
taste
tongues
chemical la in air reacting with tastebuds
touch
skin
pressure pain temperature
reflex arc sequence of events
stimuli- receptor - sensory - relay (spinal cord) - motor - effector - response
voluntary actions
- decide to carry out
- have to think
- slower and purposeful
iris
coloured ring of muscle
- alters pupil size by contracting and reacting
cornea
transparent coating in front of eye
- protects eye refracts light into eye
lens
transparent biconvex lens
- focuses light clearly into the retina
ciliary body
ring of muscle tissues
- alters shape of lens
suspending ligaments
ligament tissues (by ciliary body) - connects ciliary muscle to lens
optic nerve
nervous tissue
- carries nerve impulses to brain
retina
made of light sensitive cells - back of the eye
- cells produce nervous impulse that travels down the optic nerve
pupil
hole in iris
- allows light to enter eye
what makes up the retin
photoreceptor cells
- rods
- cones
rods
respond to light
- allows us to see in low light levels
cones
respond to colours
- different cone cells respond to red, blue and green light
how do we see in dim light
outer RADIAL muscles contract (muscles pull)
- pupil larger
how to see in bright light
inner CIRCULAR muscles contract (muscles bigger)
- pupil smaller
focusing image on the retina
- cornea reflects light
- lens produces further refraction
- an image is in focus on retina
- optic nerve carries nerve impulses to brain
seeing distant objects
- ciliary muscles relax
- suspensory ligaments pull taut
- lens pulled thin
- light doesn’t bend as much