Nervous system TOPIC 5 Flashcards
name a
suspensory ligaments
name b
iris
name c
pupil
name d
cornea
name e
lens
name f
optic nerve
name g
blind spot
name h
scelera
name i
retina
name j
ciliary muscles
what is the function of the scelera
white outer layer of the eye; it is relatively tough and strong so the eyeball is not easy to damage
what is the function of the cornea
transparent area at the front of they eyeball; lets light into the ey, cureved surface to change the direction of the rays
what is the function of the iris
controls the size of the pupil; made of muscles that contract or relax to chnage the size of the pupil, controlling the amount of light reaching hte retina
what is the function of the pupil
the hole which light enters the eye through
what is the function of the lens
a clear disc which ‘fine tunes’ the focusing of the light rays
what is the function of the suspensory ligaments and ciliary muscles
change the shape of the lens to fine focus light onto the retina
what is the function of the retina
holds the light sensitive cells
what is the function of the optic nerve
carries impulses from retina to brain
what is the function of the blind spot
the point where the optic nerve leaves the eye
what happens to the pupil in dim light
the pupil is enlarged so as much light as possible enters the eye
what happens to the pupil in bright light
the iris makes the pupil very small, reducing the light entering the eye
why does the pupil change shape in brighter lights
so that too much light doesn’t damage the delicate, light-sensitive cells
name the process which focusses light
refraction
how is the shape of the lens changed
by the contraction or relaxation of the ciliary muscles
why is it important for light to be focused on the retina
if the light is focused before and past the retina then the image formed is blurry
what is the function of the eyelid
protect the eye from physical harm
where are the radial muscles in the eye
they run outwards from the pupil like the spokes of a wheel
where are the circular muscles in the eye
arranged around the pupil
what ar ethe two set of muscles which the iris contains
- radial muscles
- circular muscles
describe the light rays entering your eye from a distant object
almost parallel
describe the light rays entering your eye from a near object
diverging very strongly
what is accomodation
the process of chnaging the shape of the lens to focus on near or distant objects
explain the eyes movements when focusing on a distant object
- cilary muscles relax
- suspensory ligaments are pulled tight
- the lens is pulled flat and tight
- light rays are only refracting slightly
explain the eyes movemetns when focusing on a near object
- cilary muscles contract
- suspensory ligaments loosen
- the lens is more curved and thicker
- refracts light rays strongly
what is homeostasis
the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to interal and external changes
what are examples of effectors
- muscles
- glands
what do receptors do
detect stimuli
what are the coordination centres and what do they do
- brain
- spinal cord
- pancreas
recieve and process information from receptors
what are the names given to nerve cells
neurons
what is the junction between neurons called
a synapse
where are the two synapses
- between the sensory neurone and the relay neurone
- between the relay neurone and the motor neurone
explain a synapse
- neurotransmitter is releasedd from the end of the anox of the sensory neurone into the synaptic cleft
- the neurotransmitter diffuses across the gap
- passes the electrical nerve impulse to the next neurone
what are the two responses of an effector
- if muscle : contract
- if gland : secrete a hormone
what are the portective membranes encasing the brain called
meninges
what are the three sections of the brain
- cerebral cortex
- cerebellum
- medula
name the part of the brain which controls body temperature
the hypothalamus
what does the cerebral cortext do
- consciousness
- intelligence
- memory & language
what does the cerebellum do
- coordinates muscular activity
- balance
what does the medulla do
- unconscious activities
- control heartbeat
- breathing
what is the order of the reflex arc
- nerve impulse
- sensory neurone
- relay neurone
- motor neurone
- muscle
what are the two types of eye defects
- myopia
- hyperopia
describe myopia
- can see close objects in clear focus
- distant objects look blurred
- light is focused infront of the retina
- lens is too curved
explain how to treat myopia
- wear glasses with a concave lens
- spread out the light from distant objects
- thicker lens
describe hyperopia
- can see distant objects clearly
- close objects are blurred
- light is focused behind the retina
- lens is too flat annd thin
explain how to treat hyperopia
- wear glasses with a convex lens
- converge the light rays before reaching eye itself
- thinner lens
what are the benefits of studying the brain
understanding how our brain works helps to develop new drugs and medical treatments for some disorders and diseases
what are the risks of studying the brain
any surgery on the brain carriers risks of damage (due to delicate structure of the brain and the invasive procedures that are used)
what is the internal body temperature
37°C
what inside the hypothalamus controls the bodys core temperature
the thermoregulatory centre
how does the thermoregulatory centre work
contains receptors that are sensitive to temperature changes in the blood flowing through the brain
what happens in the process of cooling down the body
- surface skin capillaries dilate (vasodilation), more blood flows through capillaries, transfer more energy by radiation from skin to the surrounds
- produce more sweat, water evapourates transferring energy to environment
- hairs lie flat to skin
what happens in the process of keeping the body warm
- surface skin capillaries contrict (vasoconstriction), reduces energy transferred by radiation
- sweat production is stopped
- skeletal muscles contract and relax rapidly, causing shivering, an exothermic reaction
- hairs pulled erect to trap insullating layer of air
