B10 Flashcards
homeostasis
The maintenance of the internal conditions of a cell or organism to maintain optimum conditions for function, in response to internal and external changes
CNS
The part of the nervous system where information is processed. It is made up of the brain and spinal cord
nerve
Bundle of hundreds or even thousands of neurons
neurones
Basic cells of the nervous system that carry electrical impulses around the body
stimuli
Changes in the external or internal environment that can be detected by receptors
receptors
Cells that detect stimuli - changes in the internal or external environment
sensory neurone
Neurone that carries impulses from the sensory organs to the central nervous system
motor neurone
Carry impulses from the CNS to the effector organs
synapse
Tiny gap (junction) between neurones. A chemical is released which diffuses to the next neurone and starts an impulse
effectors
Areas (usually muscles or glands) that bring about responses in the body
reflex arc
Bring about a reflex action. They involve the sense organ, sensory neurone, relay neurone and motor neurone
reflexes
Rapid automatic responses of the nervous system that do not involve conscious thought
lens
Refracts light to focus it onto the retina. The amount of refraction can be adjusted by altering the thickness and curvature
suspensory ligament
The ligaments that connect to the lens of the eye to the ciliary muscles
iris
Coloured part of the eye that contains circular and radial muscles. These relax or contract to adjust the size of the pupil
retina
The lining of the back of the eye containing two types of light receptor cells. Rods are sensitive to dim light and black and white. Cones are sensitive to colour
sclera
The tough, mostly white outer layer of the eye. It protects the eye from damage
cornea
Tough, transparent covering over the front part of the eye
optic nerve
Bundle of neurones that extend from the back of the eye and carry impulses from the retina to the brain
blind spot
Region on the retina where the optic nerve leaves the eye and there are no light receptor cells
pupil
Hole in the middle of the iris which allows light to pass though as it enters the eye
ciliary muscle
Muscles that contract and relax to change the shape of the lens of the eye
Myopia
Short sightedness, where the rays of light from close objects are brought into focus on the retina but distant objects appear blurred as the light is focused in front of the retina
hyperopia
Long sightedness, where the rays of light from distant objects can be focused clearly on the retina but the rays of light from close objects are not focused and the objects appear blurred
accommodation
The process of changing the shape of the lens to focus on the distant or near objects
medulla
Region of the brain concerned with unconscious activities such as controlling the heart rate and breathing rate
cerebral cortex
Region of the brain associated with consciousness, memory and language
cerebellum
Region of the brain concerned with coordinating muscular activity and balance
