B3.1 - Nervous system
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What does the nervous system do
• detects change in external environment and sends it to the brain
what are the three stages of a nervous response?
1) stimulus (change in environment) 2) sensory detector (detects stimulus) 3) effector (responds to an impulse)
how to glands respond to a stimuli?
release hormones
where are receptor cells found?
sense organs (eyes, ears, nose, tongue, skin)
what do receptor cells do?
change the stimuli to electric impulses to travel along neurone to CNS
what is the CNS made of?
brain and spinal cord
how is the spinal cord protected?
by the vertebrae column (backbone)
what is the stimulus for skin?
pressure, heat
what is the role of sensory neurones?
carry electric impulses from receptor cells to CNS
what is the role of motor neurones?
carry electric impulses from CNS to effectors
what is the nervous system made of?
• brain • -spinal cord • neurones
what are effectors?
muscles or glands that respond to the change in environment
what are synapses?
gaps between neurones which allows nerve impulses to travel
how do synapses work? (5)
• electrical impulse reaches the end of neurone • triggers the release of chemicals called neurotransmitters from vesicles • neurotransmitters diffuse (move down a concentration gradient) across the synapse. • neurotransmitters bind to receptors on the next neurone. • presence of the neurotransmitter causes the production of an electrical impulse in the next neurone.
how do reflex actions help?
allow us to respond to dangerous situations rapidly and automatically
give three examples of reflex actions
blinking, sneezing, flinching from a hot pan
what is a stimulus?
change in the environment to which the body needs to respond
describe the response arc
• stimulus detected by a receptor • sensory neurone carries signal (through impulse) to CNS • motor neurone carries electrical impulse from the CNS to an effector. • effector (a muscle or gland) produces the response to the stimulus
what can effect human reaction time?
caffeine, exercise
what is the role of the brain?
processes all the information collected by body and produces a co-ordinated response
medulla
unconscious activities (breathing, heart rate)
cerebellum
muscle coordination (posture, balance, speech)
cerebral cortex
conscious thought (memory, language)
Why is it hard to treat brain damage or problems in the brain?
we don’t understand it enough, easy to make mistake and cause irreversible damage