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DAT Biology > nervous system, brain, ear, eye > Flashcards

nervous system, brain, ear, eye Flashcards

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1
Q

nervous system

A

responsible for controlling most body functions, enabling organisms to recieve and respond to stimuli from their external and internal environments
signals from nervous system travel quickly, reahching in excess of 100 meters per seconf in some cases which resilts in transmission of information more rapidly than the endocrine system

is composed of both neruons (specializes nervous tussue) and neuroglia (cells that support and protect the neurons)
these cells work together and make the major organs of this system

system includes brain, spinals cord, sensory orans like the eye and ear

grouped into the central nervous system and peripheral nervous system

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2
Q

neuron structure

A

functional units of the nervous system- used to convert stimuli into electrochemical gradient and conduct these signals throughout the entire body
structure:
-dendrite: cytoplasmic extensions that recieve info and transmit it toward cell body
cell body (soma): contains neucleus and controls netabolic activity of the neuron
axon: long cellular process that transmits impulses/action potentials, away from the cell body
myelin: axons are sheathed by this insulating substance. myelin prevents leakage of signals from the axons and allows for faster conduction of impulses. it is made by glial cells known as oligodendrocytes in the central nervous system and schwann cells in the peripheral nerveous system
the axons end in swellings known as synaptic terminals
neurotransmitters are released from these terminals into the synapse
synapse is the gap betweem the axon terminals of one cell and the dendrites of the next cell
axons can be very long- ex: axon of a neuron traveling from the spinal cord to the tip of the foot.

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3
Q

dendrite

A

cytoplasmic extension of a neruon, that recieve info and transmit it toward the cell body

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4
Q

soma

A

cell body of neuron

contains the neucleus and control the metabolic activvity of the neuron

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5
Q

axon

A

long cellular process that transmits impulses or action potentials away from the cell body,
are sheathed in mylin- an insulating substance that prevents leakage of signal from the axons and allows for faster conduction of impulses
may be very long, such as an axon of a neuron travelling from the spinal cord to the tip of the foot

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6
Q

myelin

A

insulating sheath that prevents the leakage of signals from the axons and allows for faster conduction of impulses
has gaps called th nodes of ranvier where the action protential actually propogates
this occurs through a process known as saltatory (“hopping”) conduction
myelin itself is producd by glial cells known as oligodendrocytes in the central nervous system and schwann cells in the peripheral nervous system

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7
Q

nodes of ranvier

A

gaps between segments of myelin (in a neruon) where the action potential actually propagates
this occurs through a process known as saltatory (“hopping”) cinduction

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8
Q

synaptic terminals

A

also called boutons or knobs

axon ends that end in swellings

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9
Q

neurotransmitters

A

are released from the synaptic terminals into the synapse (or synaptic cleft) which is the gap between the axon terminals of one cell and the dendrites of the next cell

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10
Q

astrocytes

A

part of Central nervous system
maintain the integrity of the blood-brain barrier, regulate nutrient and dissolved gas concentrations, and absorb and recycle neurotransmitters

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11
Q

oligodendrocytes

A

part of central nervous system

myelinate CNS axons and provide structural framework for the central nervous system

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12
Q

microglia cells

A

part of the central nervous system

remove cellular debris and pathogens

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13
Q

ependymal cells

A

line the brain ventricles and aid in the production, circulation and monitoring of cerebral spinal fluid

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14
Q

satellite cells

A

part of the peripheral nervous system

surround the neuron cell bodies in the ganglia

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15
Q

schwann cells

A

in peripheral nervous system

enclose the axons in the PNS and aid in the myelination of some peripheral axons

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16
Q

neuron function

A

specialized to recieve signals from sensory receptors or from other neurons in the body
these signals create action potentials which travel the length of the axon to the nerve terminal causing the release of neurotransmitter into the synapse

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17
Q

resting potential od neuron

A

neuron is still polarized at rest due to the unequal distribution of ions between the inside and outside of the cell
the potential difference between the intracellular space and the extracellular space is called the resting potential
typically at -70 milliolts (mV)
so the inside of the neuron is more negative than the outside
difference is due to selective ionic permeability of the neuronal cell membrance and is maintained by the active transport of ions b the NA+/K+ pumps which pumps 3Na+ out of the cell for every 2K+ it transports into the cell
-uneven exchange results in one more positive charge leaving the cell than entering it creating the negative internal environment
the cell membrane is also more permeable to K+ than to Na+ allowing some of the K+ that was pumped into the cell to move back out through facilitated diffusion, making internal environment even more negative

(outside cell has more Na+ than K+, and outside has a net positive charge
inside cell has more K+ than Na, and net charge is negative)

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18
Q

depolarization (of neruon)

A

inside of cell becomes less negative and more positve

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19
Q

action potential

A

if the cell becomes sufficiently excited and depolarized (more positive inside) to reach the threshold potential, then the voltage-gated ion channels in the nerve cell membrane open in response
an action potential starts when voltage-gated Na+ channels open in response to depolarization, allowing Na+ to rush down the electrochemical gradient into the cell causing further rapid depolarization of that segment of the axon
the Na+ also causes the next portion of the axon toward the terminal
once the axon terminal reaches the synaptic terminal, a final voltage-gated channel specific for calcium os opened, which allows Ca2+ to rush in and trigger the exocytosis of synaptic vesicles containing neurotransmitters
signal goes through axon, and the high voltage there causes voltage-gated K+ channels to open and let K+ rush in
meanwhile, the voltage-gated Na+ channels also close and the Na+/K+ pump starts pumping Na+ out of cell again
this then returns cell to negative potential in a process known as repolarization

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20
Q

hyperpolarization

A

when the neuron’s voltage shoots past the resting potential and becomes even more negative than normal due to K+ still being free to leave the cell
this results in a refractory period- period of time after an action potential during which new action potentials are very hard to initiate immediately

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21
Q

neuron impulse propagation

A

axons can propagate action potential bidirectionally, but info transfer can only occur in one direction: from dendrite to synaptic terminal because the synapses operate only in one direction and because the refractor periods make the backward travel of action potentials impossible
diff axons propagate action potentials at different speeds- the greater the diameter of the axon, the more heavily it is myelinated, the faster the impulses travel

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22
Q

synapse

A

is the gap between the axon terminal of one neuron and the dendrites of another neuron
neurons may also communicate with post-synaptic cells other than neurons, such as cells in muscles or glands and these cells are effector cells
also contains lots of neurotransmitters

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23
Q

neurotransmitter

A

membrane-bound vesicles full of chemical messengers, present in the nerve terminal
when the action potential arrives at the nerve terminal and depolarizes it, the synaptic vesicles fuse with the presynaptic membrane and release neurotransmitter into the synapse
the neurotransmitter diffuse across the synapse and acts on receptor proteins embedded in the postsynaptic membrane
the released neurotransmitter leads to depolarization of the post synaptic cell and firing of an action potential

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24
Q

curare

A

drugs
blocks postsynaptic nicotinic acetylcholine recpetors, such as those on muscles so acetylcholine is unable to interact with them
this leads to muscle relaxation and paralysis by blocking the ability to constrict muscles

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25
Q

acetylcholine

A

neurotransmiitter

occurs throughout nervous sytem

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26
Q

botulinum toxin

A

pevents release of acetylcholine from the presynaptic membrane and results in paralysis

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27
Q

anticholinesterases

A

drugs
used as nerve gases and in the insecticide parathion
these substances inhibit the activity of the acetylcholinesterase enzyme responsible for degrading acetylcholine released into the synapse
so acetylcholine is not degraded and continues to affect the postsynaptic membrane, so no coordinated muscular contractions can take place

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28
Q

afferent neurons

A

neurons that carry sensory info about the external or internal environment to the brain or spinal chord

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29
Q

efferent neurons

A

neurons that carry motor commands from the brain or spinal cord to various parts of body (muscles, glands)

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30
Q

interneurons

A

participate in only local circuits, linking sensory and motor neurons in the brain and spinal cord; their cell bodies and nerve terminals are in the same location

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31
Q

nerves

A

bundles of axons covered with connective tissue

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32
Q

plexus

A

bundle of nerve fibers

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33
Q

ganglia

A

neuronal cell bodies clusters are called ganglia in the periphery
in the central nervous system they are called nuclei

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34
Q

central nervous system

A

brain + spinal chord

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35
Q

peripheral nervous system

A

somatic + autonomic

autonomic: sympathetic + parasympathetic

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36
Q

brain structure

A

made of an outer portion of cell bodies called grey matter and an inner pertion of myelinated axons called white matter
brain also divided into forebrain, midbrain, hindbrain

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37
Q

forebrain

A

aka Prosencephalon
consists of telencephalon and diencephalon

major component of telencephalon is the cerebral cortex, and the olfactory bulb

diencephalon: has the thalamus and the hypothalamus

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38
Q

cerebral cortex

A

major component of the telencephalon
highly convoluted grey matter that can be seen on the surface of the brain
the cortex processes and integrates sensory input and motor responses and is important form memory and creative thought

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39
Q

olfactory bulb

A

is the center for reception and integration of olfacotr (smell-related) input

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40
Q

thalamys

A

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

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41
Q

hypothalamus

A

control visceral functions such as hunger, thirst, sex dice, water balance, blood pressure, temperature regulation
plays an important role in the control of the endocrin esystem

42
Q

midbrain

A

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

43
Q

Hindbrain

A

rhombencephalon

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

44
Q

cerebellum

A

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

45
Q

pons

A

acts as relay center to allow the cortex to communicate with the cerebellum

46
Q

medulla

A

aka medulla oblongata

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

47
Q

brainstem

A

the midbrain, pons and medulla

48
Q

spinal cord

A

is an elongated extension of the brain that acts as the conduit for sensory information to the brain and motor information from the brain
can also integrate simple motor responses (reflexes) by itself
has an outer white matter area containing motor and sensory axons and an inner gray atter area containing nerve cell bodies
sensory info enters the spinal cord through the dorsal horn
all motor info exits the spinal cord through the ventral horn

49
Q

dorsal horn

A

sensory info enters the spinal cord through the dorsal horn

50
Q

ventral horn

A

all motor info exits the spinal cord through the ventral horn
for simple reflexes like the knee-jerk reflex, sensory fibers (entering through the dorsal root ganlion) synapse directly on the ventral horn motor fibers
other reflexes include interneurons between the sensory and motor fibers that allow for some pocessing in the spinal cord

51
Q

Peripheral nervous system

A

consists of nerves and ganglia
the central nerves that enter the CNS and the motor nerves that leave the CNS are part of the peripheral nervous system
the PNS has 2 primary divisions: the somatic and the autonomic nervous systems, each of which has both motor and sensory components

52
Q

Somatic nervous system

A

innervates (supplies with nerves) the skeletal muscles and is responsible for voluntary movement as well as reflex arcs (pathways that control motor reflexes)

53
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
includes both sensory and motor fibers
the ANS innervates caridac and smooth muscle (located in areas such as blood vessels, digestive tract, bladder, bronchi) so ANS is impotant in blood pressure control, gastrointestinal motility, excretion, respiration and reproduction

ANS is comprised of 2 subdivisions: sympathetic and parasympathetic nervous system, which act in opposition to one another

54
Q

smooth muscle

A

located in areas such as blood vessels, digestive tract, bladder, bronchi,

55
Q

sympathetic nervous system

A

responsible for “fight or flight” responses that ready the body for action in emergency situation
increases blood pressure and heart rate, increases blood flow to skeletal muscles, and decreases gut motility
also dilates the bronchioles to increase gas exchange
uses nonepinephrine as primary nerutransmitter

56
Q

nonepinephrine

A

used as primary neurotransmitter in sympathetic nervous system

57
Q

parasympathetic nervous system

A

acts to conserve energy and restore the body to resting activity levels after exertion (:rest and digest”)
it acts to lower heart rate and increase gut motility
very important parasympathetic nerve that innervates many thoracic and abdominal viscera is called the vagus nerve- uses acetylcholine as primary neruotransmitter

58
Q

vagus nerve

A

important parasympathetic nerve that innervates many of the thoracic (relating to thorax-part of body between neck and thorax) and abdominal viscera (internal organs of the body in the chest and abdomen)
uses acetylcholine as primary neurotransmitter

59
Q

acetylcholine

A

primary neurotransmitter used in vegus nerve

60
Q

lens -para and sym effect

A

sym: nothing
para: accomodation (ability to change focus from distant to near objects and vice versa)

61
Q

iris - parasympathetic and sympathetic effect

A

sym: dilates pupil
para: constricts pupil

62
Q

salivary glands- sympathetic and paraympathetic effect`

A

sym: vascoconstriction )not secreted)
para: secretion

63
Q

sweat glands parasympathetic and sympathetic effect

A

sym: secretion (specific)
para: secretion (generalized)

64
Q

heart (force and rate) sympathetic and parasympathetic effect

A

sym: increases
para: decreaes

65
Q

peripheral blood vessels sympathetic and parasympathetic effect

A

sym: constriction
para: dilation

66
Q

visceral blood vessels sympathetic and parasympathetic effect

A

sym: constriction
para: dilation

67
Q

lungs sympathetic and parasympathetic effect

A

sym: vasodilation (dilation of blood vesselv- decreases blood pressure) and bronchoconstriction
para: broncodilation (expansion of bronchal air passages), secretion

68
Q

gastrointestinal tract sympathetic and parasympathetic effect

A

sym: decreases paristalsis (involuntary constriction and relaxation of the muscles of the intestine or another canal, creating wavelike movements that push the contents of the canal forward) and secretion
para: increases paristalsis and secretion

69
Q

rectum and anus sympathetic and parasympathetic effect

A

sym: inhibits smooth muscle in rectum and constricts sphincter
para: increases smooth muscle tone and relaxes sphincter

70
Q

adrenal medula sympathetic and parasympathetic effect

A

sym: nothing
para: secretion

71
Q

bladder sympathetic and parasympathetic effect

A

sym: relaxation of the detrusor muscle (forms a layer of the wall of the bladder) and constriction of internal sphincter
para: contraction of the detrusor muscle and inhibition of internal sphincter

(detrusor muscle remains relaxed to allow bladder to store urine, but contracts during urination to release urine)

72
Q

genitalia sympathetic and parasympathetic effect

A

sym: ejaculation
para: penile erection/engorgement of clitoris and labia

73
Q

sclera

A

a thick opaque layer that covers the eyeball

the white of the eye

74
Q

choroid

A

beneath the sclera (the white of the eye)
helps supply the retina with blood
it’s dark, prigmented area reduces reflection in the eye

75
Q

retina

A

innermost layer of the eye that have photoreceptors that sense light

76
Q

cornea

A

transparent
at the front of the eye
bends and focuses light rays
the rays then travel through the opening called the pupil

77
Q

pupil

A

opening through which light rays travel

its diameter is controlled by the pigmented, muscular Iris

78
Q

iris

A

muscular, pigmented, controls the diameter of the pupil

responds to the intensity of light in the surroundings (light makes the pupil constrict)

79
Q

lens

A

suspended behind the pupil
the lens shape and focal length are controlled by ciliary muscles
focuses the image onto the retina

80
Q

ciliary muscles

A

control the shape and focal length of the lens

81
Q

photoreceptor

A

in the retina
transduce light into action potentials
2 main types: cones and rods
cones and rods contain various pigments that absorbs specific wavelengths of light

82
Q

cones

A

photoreceptors
respond to high-intensity illumination and are sensitive to color
contain various pigments that absorb specific wavelengths of light
cones contains 3 different pigments that absorb red, green, and blue wavelenghts

83
Q

rods

A

photoreceptors
detect low-intensity illumination and are important in night vision
has pigment:-rhodopsin-only absorbs a single wavelength

84
Q

blind spot

A

the point where the optic nerve, made of ganglion cells that bundle to form this, exits the eye
photoreceptors are not present there

85
Q

fovea

A

a small area of the retina above the blind spot, is densely packed with cones and is important for high-acuity vision

86
Q

rhodopsin

A

-rhodopsin-only absorbs a single wavelength

is a rod pigment

87
Q

bipolar cells

A

the photoreceptor cells synapse onto this

88
Q

ganglion cells

A

what bipolar cells synapse onto

89
Q

vitreus humor

A

jelly-like material in the eye

helps maintain its shape and optical properties

90
Q

aqueous humor

A

watery substance athat fills the space between the lens and the cornea in the eye

91
Q

myopia

A

disorder of the eye
nearsightedness
occur when the image is focused in front of the retina

92
Q

hyperopia

A

farsightedness
disorder of eye
occurs when the image is focuses behind the retina

93
Q

astigmatism

A

caused by an irregularly shaped cornea

disorder of eye

94
Q

cataracts

A

disorder of eye
develops when the lens becomes opaque
light cannot enter the eye
blindness results

95
Q

glaucoma

A

disorder of the eye
an increase of pressure in the eye because of blocking of the outflow of the aqueous humor, which results in optic nerve damage

96
Q

ear

A

transduces sound energy (pressure waves) into impulese perceived by the brain as sound
sound waves pass throught 3 regions as they enter the ear
first enter outer ear, then middle, inner ear

97
Q

outer ear

A

consists of auricle (external ear) and auditory canal

98
Q

tymphanic membrane

A

at the end of the auditory canal
part of the middle ear
vibrates at the same frequency as the incoming ound

99
Q

ossicles

A

3 bones- malleus, incus, and stapes or hammer, anvil, and stirrup
part of the middle ear
amplify the stimulus and transmit it to the oval window which leads to the fluid-filled inner ear
vibration of the ossicles exerts pressure on the fluid of the cochlea, stimulating hair cells in the basilar membrane to transduce the pressure into action potentials which travel via the auditory (cochlear) nerve to the brain for processing

100
Q

inner ear

A

consists of cochlea and the vestibular apparatus, which is involved in maintaining equilibrium

101
Q

hair cells in basilar membrane

A

stimulation of these transduce the pressure exerted by the vibration of the ossicls into action potentials whci travel via the auditory nerve to the brain for processing

102
Q

auditory nerve

A

tranfers the action potentials (converted from pressure exerted on the fluid in the cochlea by vibration) to the brain for processing

DAT Biology (7 decks)

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