Year 10 The Nervous System Flashcards
Nervous system
Electrical impulses along neurones (nerve cells)
Endocrine system
Hormones (chemical messages) via the blood
What are the two parts structurally
Central nervous system inc. brain and spinal cord
Peripheral nervous system inc. all other nerves e.g ulna nerve in arm and femoral nerve in leg
What’s a stimulus
A change in the environment which causes a response in the body that are five sense organs that can detect stimuli
Ears: receptors for and stimuli
Sound/balance in cochlea
Sound and balance
Eyes: receptors for and stimuli
Rods and cones in retina
Light
Skin: receptors for and stimuli
Temperature pressure and pain
Temperature and pressure
Nose: receptors for and stimuli
Olfactory receptors
Chemicals
Tongue: receptors for and stimuli
Found on taste buds
Chemicals
What’s a sense organ
Made up of a cluster of receptor cells which are sensitive to a specific stimuli
Oder of the nervous system
Stimulus —> receptor —> sensory neurone —> CNS —> motor neurone —> effector —> response
Stimulus
A change in the environment which causes a response in the body
Receptor
Any changes (stimuli) picked up by cells called receptors. Usually found clustered together in sense organs
Sensory neuron
Once sensory receptor detects a stimulus the info sent is chemical impulses passes along cells called neurones usually in bundles of thousands called nerves
Central nervous system
Impulses travel along neuron until it reaches CNS the cells which carry impulses from sensory organs to CNS Are called sensory neurons
Motor neuron
These cells carry impulses to make the right bits of your body. Effector organs respond
Effector
Muscles or glands which respond to the arrival of impulses by contracting
Response
Muscles respond by contracting and glands respond by secreting chemical substances
Cerebral cortex
Concerned with consciousness, intelligence, memory and language
Carebellum
Concerned with mainly coordinating muscular activity and balance
Medulla
Concerned with unconscious activities e.g. controlling the heartbeat, movement of the gul and breathing
Hypothalamus
Involved in controlling the body temperature
Pituitary gland
Produces many different chemicals/hormones which play a big part in coordinating and controlling body systems
What are reflexes for
Automatic
Rapid
Protect the body from harm or
Control basic bodily functions e.g. breathing, moving food through gut
What do reflex actions involve
Sensory neurons, synapses, relay neurons and motor neurons
At the synapse
When impulse from sensory neurone gets to synaptic knob, vesicles containing neurotransmitter mover to nerve cell membrane
Release chemicals to synaptic gap and diffuse to next neurone and attach to receptor sights on neurone
This starts electrical impulses travelling down neurone
At the synapse (arrow diagram)
Electrical impulse —> chemical messages —>electrical impulse
What is the eye
Sense organ containing many light and colour sensitive receptors
Formation of the retina
All light-sensitive cells are arranged at the back of the eye in special layer known as retina
Cornea
Changes direction of light rays coming into eye
Iris
Muscle that controls size of pupil- how much light enters the eye
Lens
Clear disk that fine-tunes focussing of light rays
Retina
Receives light that’s lens has focussed and converts to impulses to the brain
Optics nerve
Transfers visual informations from retina to visual centres of brain via electrical impulses
Binocular vision
Vision using two eyes, range of vision overlaps, can judge distance and see 3D, smaller field of view
Monocular vision
Vision using 1 eye, range of vision doesn’t overlap, wider field of view as eyes on side of head, unable to judges distance (no 3D)
Accommodation for a distant object
Relaxed muscle
Taut ligaments
Longer and flatter lens
Accommodation for a near object
Contracted muscles
Slack ligaments
Shorter and fatter lens
Muscles and ligaments in eye and function
Ciliary muscles and suspensions ligaments act together to push or pull on lens. Fatter the lens, the more the light is refracted
What is short sightedness
Myopia
Unable to focus on distant things
What is long sightedness
Hyperopia
Unable to focus on nearer objects
How can myopia be corrected
Concave lens refracts light outwards before it hits the cornea then image focuses on retina
How can hyperopia be corrected
Convex lens refracts light inwards before it hits the cornea then focuses on the retina
Advantage and disadvantage of contact lenses
Better for sport, more comfortable
Can cause eye infections, have to be sterilised at night
Advantage and disadvantage of laser eye surgery
Used to treat both myopia and hyperopia many don’t need to wear glasses/ lenses
Only available to adults once eye stops growing
Advantage and disadvantage of replacement lenses
Corrects visual impairment permanently
Damage to retina, cataracts and infection
What is laser eye surgery
Changes shape of cornea not lens
What are replacement lenses
Add contact lenses over, removes lens and replaces with new one
