The nerves system Flashcards
light rays are refracted by the…
the cornea and lens
what does the retina contain?
light receptors. some are sensitive to different colours
what does binocular vision do?
binocular vision helps to judge distances by comparing the images from each eye. The more different they are the nearer the object
how can the eye focus light from distant or near objects? what is this called?
by altering the shape of the lens. This is called accommodation
what do your eyes have to do to focus on a distant object?
the ciliary muscles relax and the suspensory ligaments tighten so the lens has a less rounded shape
what do your eyes have to do to focus on a near object?
the ciliary muscles contract and the suspensory ligaments slacken so the lens regains a more rounded shape due to its elasticity
what is accommodation?
altering the shape of the lens to focus on near or distant objects
what do the ciliary muscles do?
they control suspensory ligaments
what does is a ligament?
a short band of tough, flexible fibrous connective tissue which connects two bones or cartilages or holds together a joint.
what does the pupil allow?
light rays to enter the eye
what does the coloured iris do?
controls the amount of light entering the eye
what does the outer cornea do?
refracts the light rays
what does the convex lens do?
refracts light rays and focuses light onto the retina
what do the suspensory ligaments do?
alter the shape of the lens in focusing
what happens on the retina?
a focused image is formed, which is sensitive to light
what does the optic nerve do?
carries nerve impulses to the brain to judge what to do next
what is good and bad about having monocular vision?
they have a wider field of view but are poor at judging distances
what is good and bad about having binocular vision?
they judge distances better but have a narrower field of view
what do sense organs do (receptors)?
keep us informed of what is happening. They detect different stimuli and generate nerve impulses to transmit information to the brain
what do ears do?
detect sound and are used for balance
what do our noses do?
smell chemicals in the air
what do our tongues do?
taste chemicals in food
what do eyes do?
detect light
what does skin do?
detect pressure, temperature and pain
what causes us to have colour vision?
receptors reaction to different colours
what are receptors?
an organ or cell able to respond to light, heat, or other external stimulus and transmit a signal to a sensory nerve.
what causes long sightedness?
eyeballs or lenses the wrong shape
finish this sentence…the fatter the lens…
the more light is refracted
what happens to the eyes as you get older?
the muscles and ligaments become less flexible
how do you cure short-sightedness?
by wearing glasses or lenses with concave lenses
what does concave mean?
curving in
how do you cure long-sightedness
by wearing convex lenses
what does convex mean?
bulging out
what surgical method is used to correct focusing problems?
corneal surgery. Lasers alter the curvature of the cornea.
what are nerve cells called?
nerve cells are called neurons. Nerve impulses pass along the axon
how are neurons adapted?
neurons are adapted by being long having branched endings to pick up impulses and having an insulator sheath
what is the gap between neurons called?
a synapse.
the arrival of an impulse triggers…
the release of a transmitter substance which diffuses across the synapse.
what does the transmitter substance do?
it binds with receptor molecules in the membrane of the next neurone causing the impulse to continue
what is red-green colour blindness caused by?
a lack of specialised cells in the retina
what is long and short sight caused by?
the eyeball or lens being the wrong shape. in long sight the eyeball is too short or the lens is too thin so the image is focused between the retina. In short sight the eyeball is too long or the lens is too rounded so the lens refracts light too much so the image would be focused in front of the retina
what corrects long and short sight? (convex lens)
corneal surgery or a lens in glasses or contact lenses. A convex lens is used to correct long sight a concave lens to correct short sight
what is a reflex?
a not thought about action
how is information carried around the brain?
as nerve impulses (electrical signals) in nerve cells called neurons
what is the system of nerve impulses called?
our nervous system
what is the central nervous system made up of?
the brain and spinal cord
what is the peripheral nervous system made up of?
nerves to and from the brain and spinal cord
what are the 7 stages of a reflex arc (spinal reflex)?
stimulus-receptor-sensory neurone-relay neurone in spinal cord-motor neurone-effector-response
when dropping a hot plate what is the stimulus and what was the response?
the stimulus was the hot temperature and the response was the dropping of the plate
what is dropping a hot plate and example of?
a spinal reflex
what do sensory neurones do?
carry impulses away from sensory receptors
what do motor neurones do?
carry impulses to an effector (muscle or gland)
what re the basic characteristics of neurons?
long, have branched endings (dendrites) to pick up impulses, are insulated by a fatty sheath so that the impulses do not cross over
