biology chapter 7 Flashcards

1
Q

nervous system

A

enables organisms to receive and respond to stimuli from their external and internal environments

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2
Q

neurons

A

are the functional units of the nervous system

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3
Q

dendrites

A

are cytoplasmic extensions that receive information and transmit it toward the cell body

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4
Q

cell body (soma)

A

contains the nucleus and controls the metabolic activity of the neuron

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5
Q

axon

A

is a long cellular process that transmits impulses away from the cell body

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6
Q

myelin

A

insulating substance that cover axons, which allow axons to conduct impulses faster

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7
Q

oligodendrocytes

A

produce myelin in the central nervous system

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8
Q

schwann cells

A

produce myelin in ther peripheral nervous sytem

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9
Q

nodes of Ranvier

A

the gaps between segments of myelin

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10
Q

synapse

A

or synaptic cleft, which is the fap between the axon terminals of one cell and the dendrites of the next cell

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11
Q

action potentials

A

impulses that travel the length of the axon and invade the nerve terminal, thereby causing the release of neurotransmitter into the synapse

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12
Q

resting potential

A

when a neuron is at rest, the potential difference between the extracellular space and the intracellular space

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13
Q

typical resting membrane potential

A

is -70 millivolts (mV) which means that the inside of the neuron is more negative than the outside

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14
Q

minimum threshold membrane potential

A

(usually around -50 mV) is the level at which an action potential is initiated

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15
Q

repolarization

A

returns the cell to a more negative potential

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16
Q

refractory period

A

immediately following an action potential, it may be very difficult or impossible to initiate another action potential

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17
Q

synapse

A

the gap between the axon terminal of one neuron and the dendrites of another neuron

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18
Q

neurotransmitters

A

the nerve terminal contains thousands of membrane bound vesicles full of chemical messengers

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19
Q

curare

A

blocks the post synaptic acetylcholine receptors so that acetylcholine is unable to interact with the receptor. This leads to paralysis by blocking nerve impulses to muscles

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20
Q

botulism toxin

A

prevents the release of acetylcholine from the presynaptic membrane and also results in paralysis

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21
Q

anti-cholinesterases

A

are used as nerve gases and in the insecticide Parathion. As the name implies, these substances inhibit the activity of the acetylcholinesterase enzyme. As a result the acetylcholine is not degraded in the synapse and continues to affect the post-synaptic membrane. therefore, no coordinated muscular contractions can take place

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22
Q

afferent neurons

A

neurons that carry sensory information about the external or internal environment to the brain or spinal cord

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23
Q

efferent neurons

A

neurons that carry motor commands from the brain or spinal cord to various parts of the body

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24
Q

plexus

A

a network of nerve fibers

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25
Q

ganglia

A

clusters of neuronal cell bodies

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26
Q

central nervous system

A

consists of the brain and spinal cord

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27
Q

brain

A

the brain is a mass of neurons that resides in the skull. Its functions include interpreting sensory information, forming motor plans, and cognitive function (thinking). The brain consists of an outer portion called the gray matter (cell bodies) and an inner white matter (myelinated axons). the brain can be divided into the forebrain, midbrain, and hindbrain)

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28
Q

forebrain (prosencephalon)

A

the forebrain consists of the telencephalon and the diencephalon

29
Q

cerebral cortex

A

which is the highly convoluted gray matter that can be seen on the surface of the brain

30
Q

olfactory bulb

A

is the center for reception and integration of olfactory input

31
Q

diencephalon

A

contains the thalamus and hypothalamus

32
Q

thalamus

A

is a relay and integration center for the spinal cord and cerebral cortex

33
Q

hypothalamus

A

controls visceral functions such as hunger, thirst, sex drive, water balance, blood pressure, and temperature regulation

34
Q

midbrain

A

is a relay center for visual and auditory impulses. It also plays an important role in motor control

35
Q

hindbrain

A

is the posterior part of the brain and consists of the cerebellum, the pons and the medulla

36
Q

cerebellum

A

helps to modulate motor impulses initiated by the cerebral cortex, and is important in the maintenance of balance, hand-eye coordination, and the timing of rapid movements

37
Q

pons

A

is to act as a relay center to allow the cortex to communicate with the cerebellum

38
Q

medulla

A

controls many vital functions such as breathing, heart rate, and gastrointestinal activity

39
Q

brainstem

A

constituted by the midbrain, pons, and medulla

40
Q

spinal cord

A

is an elongated extension of the brain which acts as the conduit for sensory information to the brain and motor information from the brain

41
Q

peripheral nervous system

A

consists of nerves and ganglia

42
Q

somatic nervous system

A

innervates skeletal muscles and is responsible for voluntary movement

43
Q

autonomic nervous system

A

also called the involuntary nervous system because it regulates the body’s internal environment without the aid of conscious control

44
Q

sympathetic nervous system

A

is responsible for the “flight or fight” responses that ready the body for action in an emergency situation. It increases blood pressure and heart rate, it increases blood flow to skeletal muscles and it decreases gut motility. It also dilates the bronchioles to increase gas exchange. it uses norepinephrine as its primary neurotransmitter

45
Q

parasympathetic nervous system

A

acts to conserve energy and restore the body to resting activity levels following exertion (“rest and digest”). It acts to lower heart rate and to increase gut motility. It uses acetylcholine as its primary neurotransmitter

46
Q

the eye

A

detects light energy (as photons) and transmits information about intensity, color, and shape to the brain

47
Q

sclera

A

thick, opaque layer that covers the eyeball. It is also known as the white of the eye

48
Q

choroid layer

A

which helps to suppy the retina with blood. It is a dark, pigmented area that reduces reflection in the eye

49
Q

retina

A

innermost layer of the eye, which contains the photoreceptors that sense light

50
Q

cornea

A

transparent at the front of the eye, bends and focuses light rays

51
Q

iris

A

responds to the intensity of light in the surroundings

52
Q

lens

A

suspended behind the pupil and focuses the image onto the retina

53
Q

photoreceptors

A

that transduce light into action potentials

54
Q

cones

A

respond to high intensity illumination and are sensitive to color

55
Q

rods

A

detect low intensity illumination and are important in night vision

56
Q

rhodopsin

A

absorbs a single wavelength

57
Q

blind spot

A

the point at which the optic nerve exits the eye because photoreceptors are not present there

58
Q

aqueous humor

A

is the thick watery liquid between the lense and cornea formed by the eye and exits through ducts to join the venous blood

59
Q

myopia (nearsightedness)

A

occurs when the image is focused in front of the retina

60
Q

hyperopia (farsightedness)

A

occurs when the image is focused behind the retina

61
Q

astigmatism

A

is caused by an irregularly shaped cornea

62
Q

cataracts

A

develop when the lens becomes opaque; light cannot enter the eye and blindness results

63
Q

glaucoma

A

is an increase of pressure in the eye due to the blocking of the outflow of the aqueous humor

64
Q

the ear

A

transduces sound energy (pressure waves) into impulses perceived by the brain as sound

65
Q

outer ear

A

which consists of the auricle (external ear) and the auditory canal

66
Q

tympanic membrane

A

(eardrum) of the middle ear, which vibrates at the same frequency as the incoming sound

67
Q

ossicles

A

(malleus, incus, and stapes) amplify the stimulus, and transmit it through the oval window

68
Q

inner ear

A

consists of the cochlea and the vestibular apparatus

69
Q

vestibular apparatus

A

is involved in maintaining equilibrium