the mucous membrane that covers the front of the eye and lines the inside of the eyelids
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iris
a flat, coloured, ring-shaped membrane behind the cornea of the eye, with an adjustable circular opening (pupil) in the centre.
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pupil
the dark circular opening in the centre of the iris of the eye, which varies in size to regulate the amount of light reaching the retina
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cornea
the transparent layer forming the front of the eye and acts like the outermost lens
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lens
a transparent convex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina
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ciliary muscle
muscle(s) that alter the curvature of lens
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suspensory ligament
a series of fibres that connect the ciliary body of the eye with the lens, holding it in place.
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retina
a layer at the back of the eyeball that contains cells sensitive to light, which trigger nerve impulses that pass via the optic nerve to the brain, where a visual image is formed.
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fovea
a small depression in the retina of the eye where visual acuity is highest. The centre of the field of vision is focused in this region, where retinal cones are particularly concentrated.
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optic nerve
transfers visual information from the retina to the vision centres of the brain
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cones
active at higher light levels of light, are capable of colour vision and are responsible for high spatial acuity
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rods
are responsible for vision at low light levels (scotopic vision)
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diffusion
the net movement of anything from a region of higher concentration to a region of lower concentration
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nodes of ranvier
gaps in the myelin sheath surrounding an axon. said myelin sheath is largely composed of an insulating fatty substance so these nodes allow faster electrical impulses along the axon
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receptor
cells primed to "read" or receive a kind of input or stimulus and transmit this via a reflex arc
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effector
parts of the body, such as muscles and glands, that produce a response to a detected stimulus e.g., a muscle contracting to move an arm.
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stimulus
a detectable change in an internal or external environment
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response
a change in the organism resulting from the detection of a stimulus.
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synapse
a junction between two nerve cells, consisting of a minute gap across which impulses pass
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motor
mooooooooooooooovement
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sensory
sensation or input, as can be detected by sensory organs
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neurotransmitter
chemicals released at the neurone axon terminal when electrical impulses pass through, the chemicals travel across the gap and stimulate an electrical impulse in the next neurone
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gland
an organ in the human or animal body which secretes particular chemical substances for use in the body or for discharge into the surroundings
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nervous system
the network of nerve cells and fibres which transmits nerve impulses between parts of the body (comprised of CNS and PNS)
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neurone
a specialised cell transmitting nerve impulses; a nerve cell
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dendrite
a short branched extension of a nerve cell, along which impulses received from other cells at synapses are transmitted to the cell body
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cell membrane
the semipermeable membrane surrounding the cytoplasm of a cell
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nucleus
the brain/control centre of the cell
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cytoplasm
a thick solution that fills each cell and is enclosed by the cell membrane. It is mainly composed of water, salts, and proteins
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axon
very long and thin strand that snakes away from the main part of the cell. It is several times thinner than a human hair and it is where electrical impulses from the neurone travel away to be received by other neurones.
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myelin sheath
an insulating layer made of fat and protein, covers the axon except for the gaps known as the nodes of RANVIER
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nerve ending
one of the fine branches at the end of a neurone, by which it makes contact either with another neurone or with a muscle or gland cell
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unidirectional
A ONE WAY SYSTEM ONLY!!
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Other cards in this set
Card 2
Front
iris
Back
a flat, coloured, ring-shaped membrane behind the cornea of the eye, with an adjustable circular opening (pupil) in the centre.
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