Human Nervous System and Sensory Organs Flashcards
keycards
accommodation
the ability of the lens to alter its shape for clear vision
Alzheimer’s disease
disease caused by nerve defects usually in older people and characterized by memory loss and confusion
Astigmatism
Eye defect caused by an uneven corneal surface
Auditory Nerve
nerve transmitting impulses from the ear to the brain
Autonomic nervous system
nervous system containing a sympathetic and parasympathetic section
Binocular vision
the use of 2 eyes to form an image, giving a wider field of vision
Blind-spot
area in the retina that does not contain photoreceptors and therefore cannot form an image
cataract
cloudy ,opaque portion in the lens of the eye
central nervous system
nervous system made up of the brain and the spinal cord
cerebellum
the part of the brain which co-ordinates voluntary actions and which is responsible for balance
cerebrum
- the region of the brain associated with problem solving
- the part of the brain where the sensation of sound is interpreted
choroid
a pigmented layer in the eye which absorbs light and prevents its reflection
ciliary muscles
muscles that contract or relax to change the shape of the lens in the eye
cones
Receptor cells, sensitive to colour found in the eye
conjunctive
protection membrane situated over the cornea of the eye
cornea
transparent part of the sclera in front of the eye
cristae
receptors in the semi-circular canals of the ear that are sensitive to speed and direction
dendrites
fibres that transmit impulses to a cell body in a neuron
effector
structure that responds to a stimulus received by a receptor/sensory organ
eustachian tubes
tubes which connects the middle ear to the pharynx
grommet
structure inserted into the tympanic membrane to allow air to pass into the middle ear
Interneuron
neuron that transmits impulses from the sensory neuron to the motor neuron
Iris
the part of the eye which is colored black, brown, green, grey, or blue
long-sightedness
the ability to see objects far away clearly, but not objects close by
maculae
receptors in the sacculus and utriculus of the ear that are sensitive to the position of the body
medulla oblongata
A part of the brain responsible for the involuntary actions such as breathing and dilation and constriction of blood vessels
Meninges
protective membranes surrounding the central nervous system to effectors
multiple sclerosis
Disease caused by damage to the myeline sheth of neurons and characterized by physical and mental disablities
myelin sheath
the structure that insulates a neuron in order to speed up the transmission of impulses
neuron
the structural unit of the nervous system
optic nerve
nerve transmitting impulses from the eye to the brain
Organ of Corti
the structure, within the cochlea, responsible for picking up the stimulus of sound
peripheral vision
nerves linking receptor and effector organs with the brain and spinal cord
pupillary mechanism
changes that occur in the diameter of the pupil under different light conditions
radial muscles
the iris muscles that contract in dim light
receptor
structure that receives a stimulus and converts it into an impulse for transmission
Reflex action
A rapid, automatic (involuntary) response to an external stimulus
Reflex arc
Path taken by an impulse during a reflex action
Retina
The layer of the eye containing photoreceptors and where images are formed
Rods
Photoreceptors in the retina that are stimulated under dim-light conditions
Sensory neuron
the neuron that transmits impulses from the sense organs t the central nervous system
short-sightedness
the ability to see objects close by clearly, but not objects that are far away
suspensory ligaments
structures that hold the lens of the eye in position
synapse
the physiological connection between the axon of one neuron and the dendrite of another
Yellow spot
- the area of the retina with the highest concentration of cones
- the area of the retina that contains the highest amount of cones and therefore forms the clearest image
