Quizlet Y10 Flashcards
What is the nervous system?
The network of nerve cells that transmits nerve impulses between parts of the body
What are neurones?
Basic cells of the nervous system that carry electrical impulses around the body
What is in the central nervous system?
The brain and the spinal cord
What is the peripheral nervous system?
The parts of the nervous system outside the brain and spinal cords (like neurones)
What is a stimulus?
A change in an organism’s surroundings
What is a receptor?
A structure that allows a living organism to sense the conditions of their internal or external environment
What is a sensory neurone?
A neurons that carries impulses from the sensory organs to the CNS
What is a coordinator?
The CNS, which formulates a response to a stimulus before sending impulses to an effector
What is a motor neurone?
A neurone that sends impulses from the CNS to an effector
What is an effector?
A structure that acts in response to a stimulus, like muscles contracting or glands secreting hormones
What is a response?
A reaction to a stimulus
What is a reflex arc?
A nerve pathway involved in a reflex action, made of a sensory neurone, relay neurone and motor neurone
What is a relay neurone?
A type of neuron found in the spinal cord involved in reflex actions
What is a reflex response?
A quick and involuntary reaction to a stimulus
What is a synapse?
A gap between neurones where information is transmitted from one neurone to the next in chemical form
What is a neurotransmitter?
A chemical that is released from the ends of an active neurone and diffuses across the synapse to other neurons
What is the brain?
A mass of nerve tissue consisting of billions of interconnected neurones.
What is the cerebral cortex?
The outer region of the cerebrum which controls memory, consciousness, language, thought, perception and memory
What is the cerebellum?
Part of the brain which controls fine motor skills, like coordination, precision and accurate timing
What is the medulla?
The base of the brainstem which controls heartbeat and breathing (unconscious activities)
What is the eye?
A sense organ which detects light and is responsible for vision
What is the sclera?
The white outer part of the eye which provides protections
What is the cornea?
The transparent tissue that covers the front of the eye and controls and focuses the entry of light into the eye. It is fixed and can’t adjust its focus
What is the iris?
The coloured part of the eye behind the cornea that regulates the size of the pupil to regulate the amount of light that reaches the retina
What is the pupil?
The dark opening in the centre of the iris
What is the lens?
A transparent structure located behind the iris which focuses light onto the retina. It can change shape to adjust focus
What are the ciliary muscles?
Muscles which work with the suspensory ligaments to adjust the shape of the lens in order to focus on near/far objects
What are suspensory ligaments?
Ligaments which work with the ciliary muscles to adjust the shape of the lens in order to focus on near/far objects
What is the retina?
The light-sensitive surface at the back of the eye, containing light and colour receptor cells
What is the optic nerve?
The nerve that carries neural impulses from the receptor cells of the eye to the brain
What are rod cells?
light receptor cells- highly sensitive and responsible for vision in dimly lit conditions
What are cone cells?
colour receptor cells, responsible for the perception of colour
What is the reflex response to dim light?
circular muscles relax, radial muscles contract so the pupil widens
What is the reflex response to bright light?
circular muscles contract, radial muscles relax so the pupil constricts
What happens to the eye so it can focus on a near object?
ciliary muscles contract and suspensory ligaments loosen, making the lens thicker so it refracts the light rays more strongly
What happens to the eye so it can focus on a distant object
ciliary muscles relax and suspensory ligaments pull tight, making the lens thinner so it only slightly refracts light rays
What is hyperopia?
long-sightedness- the person has difficulty focusing on nearby objects because the light rays focus behind the retina
What is myopia?
short sightedness- the person has difficulty focusing on distant objects because the light rays focus in front of the retina
What are the causes of hyperopia?
the lens is too weak or the eyeball is too short
What are the causes of myopia?
the lens is too strong or the eyeball is too long
What lens is used to correct myopia?
concave lens
How do concave lenses work?
They spread out the light rays so that the image focuses on the retina
What lens is used to correct hyperopia?
convex lenses
How do convex lenses work?
they refract light inwards so the image focuses on the retina