Homeostasis ONLY FOR AUTUMN TEST Flashcards
nervous system allows you to…
know what is going on in your surroundings
the nervous system carries… travelling at between … and …m/s
electrical signals
1
120
stimuli
changes
receptors
- similar to animal cells
- found clustered together in special sense organs (e.g. eyes, skin)
- detects stimuli
the path
- sensory receptor detects stimulus
- electrical impulse sent passing along sensory neurones
- impulse reaches central nervous system
- brain coordinates response + sends out impulses
- travels along motor neurones to effectors
- effector responds
pathway condensed
stimulus, receptor, coordinator, motor neurone, effector
Reflexes
- help to avoid danger because they happen so fast
- includes basic bodily functions e.g. breathing, digestingq
3 kinds of neurone involved in pain withdrawal reflex
- sensory
- motor
- relay
reflex arc
- electrical impulse passes from receptor along the sensory neurones
- arrives at CNS
- passes along a relay neurone (usually in spinal cord)
- and goes straight back along motor neurone
- arrives at effector which responds
reflexes details: receptor + sensory neurone
- when object is touched, receptor in the skin is stimulated
- electrical impulse is sent out along a sensory neurone
reflex details: synapse + relay neurone
- when impulse arrives at synapse between sensory and relay neurone, a chemical is released
- chemical diffuses across synapse to relay neurone (in spinal cord so part of CNS)
- where it sets off a new electrical impulse which travels across relay neurone
reflex details: relay -> motor neurone
- when the impulse reaches the synapse between motor and relay neurone, another chemical is released which diffuses across the synapse
- sending another impulse down the motor neurone
reflex details: effector
- when impulse reaches effector organ its stimulated to respond
- impulses arrive in the muscles, causing to contract
- or reaches the gland, which secretes chemical substances
difference between normal path and reflex path
coordinator is a relay neurone (in spinal cord or unconcious part of brain) instead of CNS
reflex pathway
stimulus, receptor, sensory neurone, relay neurone, motor neurone, effector, response
effect of a factor on human reaction time: potential factors
- age
- temp
- alcohol
- drugs
- caffeine
measuring reaction time methods
- ruler drop test
- stand in a circle holding hands eyes closed and see how long for squeeze to pass around
peripheral nervous system
all other nerves connecting to the CNS, made up of neurons
parts of a motor neurone
dendrite, cell body, nucleus, myelin sheath, axon, axon terminal
which side does impulse come from on motor neurone
from cell body to axom terminal
what are those chemical messengers called?
neurotransmitters
how wide is the synapse
20 nanometres
the neurotransmitter binds with a… which…
receptor molecule on the membrane of the postsynaptic neurone which stimulates a new nerve impulse im the postsynaptic neurone
finally, the chemical messenger is… back into the… ready to be used again
reabsorbed
presynaptic neuron
function of the brain
- information from sensory receptors feeds into the brain
- info is processed
- impulse is sent along a motor neurone to coordinate response
parts of the brain + functions
cerebral cortex - memory, consciousness and intelligence
cerebellum - coordination of muscular activity and balance
medulla oblongata - unconcious acitivities e.g. heartbeat
hypothalamus - thermoregulation
pituitary gland - chemical messages (hormones)
difficult to study brain bc…
- complex and delicate
- lots of neurones
- lots of pathways (synapses)
- encased by skull
- lots of neurotransmitters
- difficult to treat bc most medicines cant get in the brain
- surgery is hard as not all areas are fully understood
techniques to ‘map’ the brain
- MRI scan
- autopsy/dissection
- electrically stimulating different parts
- studying people with brain damage
