The Human Nervous System Flashcards
(37 cards)
How does the nervous system protect us from harm
By responding to changes in the environment
Parts of the nervous system
The brain - coordinates response of effectors
Spinal cord - helps coordinate responce of effectors
Neurones ( nerve cells) - carry electrical impulses between the receptors, central nervous system and effectors
What are synapses
Gaps between neurones which can be found at each junction of a reflex arc. Nerve impulses travel across them
What happens when the nerve impulse arrives at the synapse
Triggers the release of chemicals called neurotransmitters
How to electrical impulses travel across synapses
The neurotransmitters diffuse across the synapse
They bind to the receptors on the next neurone
The presence of the neurotransmitter chemical causes the production of an electrical impulses in the next neurone
What are reflex actions
Action that is done automatically and rapidly without conscious thought
Eg blinking
Sneezing
Dropping hot objects
Components of a reflex arc
Stimulus - change in environment to which body needs to respond
Receptor - detect change and initiate signals
Sensory neurone - carrys signals in form of electrical impulses to the central nervous system
Relay neurone ( in Central nervous system) - relays the electrical impulses from the sensory neurone to the appropriate motor neurone
Motor neurone - carry the electrical impulses to an effector
Effector - muscle or gland that brings about the action in response to the internal or external change in environment
Response - any action that helps the organism to avoid harmful situation
Brain function
Made up of millions of intoconnecting neurones
Different regions are responsible for different functions
Neurones =
Nerve cells
Why is treating brain damage complex
The brain is delicate complex and not well understood
Cerebellum
Found at the bottom at the back of the brain
Responsible for muscle coordination eg movement and speech
Cerebral cortex
Lies on top of the cerebral cortex
Responsible for conscious thought eg memory language and intelligence
Medulla
Where the brain meets the spinal cord
Responsibel for unconscious activitys eg breathing and heartbeat
How do mri scanners help with understanding the brain
Have allowed us to learn which areas of brain are active during different activitys
Hiw does brain damage help to understand the brain
By studying patients with brain damage neuroscientists can link particular parts of the brain to particular functions
How does selectocal stimulation help with understanding the brain
Can be used to treat conditions like parkinsons as the brain communicates using electrical impulses
Retina scanning
Looks at the pattern of blood vessels in your retina to identify you
What is pupil
Hole in the centre of the iris through which light passes to get to retina
What is iris
Controls pupil diameter and Hereford quantity of light reaching retina
What is ciliary muscles
Muscles which change shape of the lens which the eye u3se to focus light
What is suspensory ligaments
Fibres that connect ciliary muscles to lens
What is accommodation
The process of lthe lens in your eye changing chape to focus on an object as its distance from the eye changes
Done by suspensory ligaments and ciliary muscles
Focusing on close object
Ciliary muscles contract
Suspensory ligaments loosen
Lens becomes thicker and rounder
Results in significant refraction of light rays
Focusing on distant object
Ciliary muscles relax
Suspensory ligaments tighten
Lens becomes flatter and thinner
Results in minor refraction of light rays
