Bio 30 Unit A Module 1 (Part 1)

Front 1

accommodation

Back 1

the process of changing the shape of the lens from round and fat to thin and flat, and vice versa, so that light can be focused on the retina to accommodate vision of objects near and far away

Front 2

acetylcholine

Back 2

one of the most common neurotransmitters of both the somatic nervous system and the parasympathetic nervous sy

Front 3

action potential

Back 3

the change in charge that occurs when the gates of the potassium ion channels close and the gates of the sodium ion channels open; a large depolarization event that is conducted along the membrane of a nerve cell or a muscle cell

Front 4

adaptation

Back 4

the process by which the iris adjusts the diameter of the pupil based on light conditions, thus controlling the amount of light that enters the eye and strikes the retina

Front 5

all-or-none response

Back 5

action that occurs either completely or not at all, such as the generation of an action potential by a neuron

Front 6

amplify

Back 6

to increase the amplitude or the extent of a vibration; see intensity

Front 7

anterior chamber

Back 7

the space in front of the iris and behind the cornea that is filled with aqueous humour

Front 8

aqueous humour

Back 8

a clear, watery fluid in the anterior chamber of the eye that maintains the shape of the cornea and provides oxygen and nutrients for the surrounding cells, including those of the lens and the cornea

Front 9

astigmatism

Back 9

an uneven curvature of the cornea or lens, resulting in uneven focusing, which results in poor vision

Front 10

auditory canal

Back 10

a short channel that funnels sound waves from outside the ear to the tympanum and amplifies sounds

Front 11

auditory nerve

Back 11

a nerve composed of sensory fibres from the organ of Corti, the vestibular apparatus that conducts impulses to the temporal lobe of the cerebrum

Front 12

automatic nervous system (ANS)

Back 12

a division of the peripheral nervous system that conducts nerve impulses to cardiac and smooth muscles, as well as to glands; may also be called the involuntary motor system

Front 13

axon

Back 13

the long extension that emerges from the cell body and conducts the nerve impulse away from the cell body The axon may be up to 1 m long in motor neurons.

Front 14

axon terminal

Back 14

numerous endings found at the end of an axon Axon terminals are enlarged into knobs that are specialized for producing, storing, and releasing neurotransmitters.

Front 15

basilar membrane

Back 15

one of two parallel membranes that comprise the organ of Corti in the inner ear Hair cells are attached to the basilar membrane.

Front 16

bipolar cells

Back 16

specialized sensory nerve cells located in the retina that are stimulated by either rods or cones Cones mostly have a one-to-one ratio with bipolar cells, whereas several rod cells may communicate with one bipolar cell.

Front 17

blind spot

Back 17

the area at the back of the eyeball that is deficient in rods and cones; the area where the sensory fibres come together to form the optic nerve

Front 18

cataract

Back 18

a cloudy or grey-white area on the lens caused by deterioration of the protein composing the lens Cataracts prevent the passing of light to the photoreceptors of the retina.

Front 19

cell body

Back 19

the part of a neuron that contains the nucleus and other cell organelles for carrying out the metabolic reactions of the nerve cell; relays the nerve impulse from the dendrites to the axon

Front 20

central nervous system (CNS)

Back 20

the part of the nervous system that includes the brain and spinal cord

Front 21

chemoreceptor

Back 21

a sensory receptor that transmits information about the solute concentration in a solution or about individual kinds of molecules in solution

Front 22

cholinesterase

Back 22

an enzyme necessary to decompose acetylcholine in the synaptic cleft so that the products (choline and ethanoic acid) can be reabsorbed by the presynaptic membrane; also called acetylcholinesterase

Front 23

choroid

Back 23

the middle layer of the eye ball that lies between the sclera and retina and is highly vascular and heavily pigmented. The choroid absorbs stray light rays not detected by the photoreceptors of the retina

Front 24

ciliary muscle

Back 24

a ring of muscle behind the iris that is attached to the lens by suspensory ligaments and is involved in changing the shape of the lens

Front 25

cochlea

Back 25

contains the organ of Corti, which functions to convert the mechanical energy of sound waves into a nerve impulse