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mcat biology chapter 12 nervous system kaplan


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nerv syst lets org resp to
fuct units of nerv syst
neuron consists of
dendrites, cell body, axon
____________ receive inform and transmit towards the body
soma is
neuron cell body
Axon hillock does what?
connects the cell body to the axon
____________ transmits impulses away from cell body
myelin is ?
insulating susb that covers axons
glial cells make?
Who make myelin in the cns?
who makes myelin in the pns?
schwann cells
when an auto immune disease destroys the myelin what happens
slows information transfer.
name one common demyelinating disorder?
multiple sclerosis
the myelin of what is select targeted in ms?
myelin of brain and spinal cord
ms patients symptoms?
weakness, lack of bal, vision prob, incont
nodes of ranvier?
gaps betw segm of myelin
______________ are gaps betw segm of myelin
nodes of ranvier
axons end in swellings called?
synaptic terminals or symaptic boutons
what are released from the synapse?
synaptic left is?
gap betw axon and dendrites of next neuron cell
nerve impulses are?
action potentials
action potentials travel the lenght of the ______________
resting potential
pot diff betw extracell space and intracell space
typical ret membr potent is ?
-70 millivolts
inside of the neuron is ________________ compared to outside
more negative
membr potent of neur is maintained by
na+/K+ pump
na+/K+ pump is also called?
na+/K+ ATPase
concentr of K+ is higher where?
inside the cell
concentr of na+ is higher where?
outside the c
t or f
negative charged prot are trapped outside the c
they are trapped inside the cell
neurons do not allow much of what to enter the cell?
Na+/K+ pumps what?
3 Na+ out for every 2 K+ in.
depolarized neurons become?
less negative
a depolarized neuron bec less?
what is the minimum threshold membr potent?
around -50 mV
Na+ wants to go into the c bec of what 2 things?
electr gradient and chem gradient
an act potent begins when?
volt gated na+ channels open
Na+ goes down its?
electrochem gradient
after na+ gates open what happens?
voltage gated k+ channels open, letting k+ rush out of the c. making cell more negat again
when k+ rushes out of the c it returns the c to a ?
negative potential
cell can become more negat than its resting state. this is called?
hyperpolarization is due to
K+ rushing down its electrchem grad (moving out of the cell)
refract period
after act potent, when its hard to start anoth act potential
action pot is often descr as a
all or none response
neuron informat is coded by?
freq and number of act potential but not the size of the act potent
________________ does not code for neuron informat
size of the act potent
puffer fish prod what toxin?
TTX is
tetrodotoxin does what?
blocks the voltage gated na+ channels
local anesthetics work by
blocking teh voltage gated na+ channels
why do local anesthetics work well on sensory neurons?
cause sens neurons have small axonal diam and have little of no myelin. it makes it easier to prev act potent
act pot is initiated at?
axon hillock
as na+ rushes into the neuron and diff into adj parts of the axon it causes what?
other nearby volt gated na+ channels to open
what chain of events happens along the length of the axon?
depolarization followed by subsequent repolarization
inform transf occurs in _____________ direction
action pot are propagated in what direct?
dendrite to synaptic terminal
refractory periods make what impossible?
backward travel of action potent
as diameter and amount of myelination incr _____________________
impulses travel faster
myelin ____________________ segments of the axon
salotatory conduction is when
act potential jumps from node to node
effector cells
cells in muscles or glands that communic w neurons
most synapses are __________
chem synapses
nerve term has membr bound vesicl with?
neurotransmt diff across synapse and acts on ?
recept proteins
the symaptic vesicles fuse w presynaptic membr thr a ________________ process of exocytosis
calcium depend
neurotransm can have what 2 effects?
inhib or excitatory
3 ways neurotransm is removed from synapse
1. taken back up thr uptake carrier
2. degraded by enzymes like acetycholinesterase
3. just diffuse out
which enzyme inactiv acetycholine
what protein takess the neurotransm back up into nerve terminal?
uptake carrier
afferent neurons are?
sensory neurons
efferent neurons are?
motor neurons
afferent neurons carry information to?
brain or spinal cord
nerves that carry commands from brain to body are?
efferent neurons
interneurons are?
local circuits, cell bodies and nerve term are in same place
nerves are _______________
bundles of axons
sensory nerve has only
sensory fibers
mixed nerve has?
both sensory and motor fibers
ganglia are?
clusters of neuronal cell bodies
clusters of neuronal bodies in cns are called?
nerv system is divid into?
cns and pns
amyotrophic lateral scelrosis affects only
motor neurons
ALS is also called
lou gehrig's disease
ALS stands for
amyotrophic lateral sclerosis
central nerv syst is made up of?
brain and spinal cord
periph nerv syst is made up of?
somatic and autonomic nerv systm
autonomic nerv syst is made up of?
sympathetic and parasympathetic nerv systm
brain consists of what kinds of matter?
gray matter and white matter
in the brain, gray matter is?
cell bodies
white matter in the brain is?
myelinated axons
name 3 major parts of brain?
forebrain, midbrain, and hindbrain
The forebrain consists of?
telencephalon and diencephalon
Telencephelon consists of?
righ and left hemispheres
The right and left hemispheres of the telencephelon have what 4 lobes?
frontal, parietal, temporal, and occipital
Cerebral cortex is a major compon of?
cerebral cortex is?
highly convolut gray matter
cerebral cortex does what?
proc and integr sens input and motor resp. It is important for memory and creative thought
right and left cerebr cortices communicate thr?
corups callosum
diencephelon contains?
thalamus and hypothalamus
Thalamus is?
relay and integrat center for spinal cord and cerebral cortex
hypothalamus controls?
hunger, thirst, sex drive, water bal, bl press and and temper regulat and is imp in endocr systm
alcohol has a big effect on what part of the brain?
midbrain is ?
elay center for visual and audit impulses and is imp in motor contr
hindbrain is made up of?
cerebellum, pons, and medulla
cerebellum does what?
modul motor impulses init by motor cortex.
What part of the brain is imp in balance, hand eye coordin and rapid movements?
pons does what?
acts as relay center to let the cortex commun with the cerebellum
The pons helps the ___________ to communiate w the cerebellum
medulla oblangata controls?
breathing, heart rate, gastrointest activ,
brainstem is made up of?
midbrain, pons, medulla
midbrain, pons, and medulla make up the?
spinal cord goes down the ____________ side of vertebrates
spinal cord has outer _____________ and inner ______________
outer white matter, inner gray matter
in spinal cord, outer white matter has?
motor and sensory axons
in spinal cord, inner gray matter has?
nerve cell bodies
sensory informat enters the spinal cord?
cells of sensory neurons are locat in ?
dorsal root ganglia
motor informat exits the spinal cord?
IN the spinal cord roots are?
nerve branches entering and leaving the cord
spinal cord is made up of what 4 regions?
cervical, thoracic, lumbar, sacral
pns has 12 pairs of?
cranial nerves
Pns has _______ pairs of cranial nerves and _________ pairs of spinal nerves
12 pairs of cranial nerves and 31 pairs of spinal nerves
pns has what 2 primary divisions?
somatic and autonomic nerv syst
somatic nerv syst is resp for?
voluntary movement
motor neurons release what neurotransm?
somatic nerv syst is resp for volunt movement and ?
reflex action
name 2 types of reflexes?
monosynaptic and polysynaptic
describe a monosynaptic reflex?
one synapse betw sens and motor neuron
in knee jerk reflex what senses the hit of the hammer?
stretch receptors
in what disease does the body do an immune react against acetycholine recept on skel muscle?
myasthenia gravis
in myasthenia gravis what happens?
immune syst attacks Ach recept on skel muslce
withdrawal reflex is a ____________ reflex
polysynaptic reflex
withdrawal reflex is a ?
polysynaptic reflex
in a polysynaptic reflex sesnory neurons?
symapse w more than one neuron
In withdrawal reflex one leg ___________ , and one leg?
one leg moves off the nail and one leg extends to keep your balance
ANS is
autonomic nervous system
ANS innvervates?
cardiac and smooth muscle
name 4 places where smooth muscles is found?
bl vess, dig tract, bladder, bronchi
ANS has a ______________ system
2 neuron system
what are 2 neurons of ANS?
preganglionic neuron and postgangionic neuron
in ANS preglionic neuron has a cell body in the>?
The axon synapse of the ANS preglionic neuron is in ?
peripheral ganglia
postganionic neuron has its cell body _______________ and synapses on ______?
cell body in ganglia, synapses on cardiac or smooth muscle
ANS is made up of?
sympathetic and parasympathetic nerv systm
fight or flight comes from?
symp nerv syst
sympath nerv syst does what to the body?
incr bl press and hr, incr bl flow to sk muscles and decr gut mobility
in sympath nerv syst, the preganglionic neurons emerge from?
thoracic and lumbar regions of spinal cords
symph nerv syst the preganglionic neurons use?
symp nerv syst the postganglionic neurons release?
first neuron in ans is called ?
preganglionic neuron
second neuron in ans is called ?
postganglionic neuron
the preganglionic symp neurons cause the adrenal medulla to ?
release adrenaline
Which neurons of the ans cause adrenal medulla to release adrenaline (epinephrine)
preganglionic neurons
parasymph system is the ?
rest and digest
Which part of ANS does "rest and digest"?
parasymph nerv systm
parasymp does what to hr?
lowers it
vagus nerve is part of ?
parasymp nerv syst
Which nerve innervates many of thoracic and abdom viscera?
vagus nerve
parasymp nerves originate in?
brainstem (cranial nerves) and sacral part of spinal cord
parasym ns
pregangl and post gangl neurons release?
sympath ns has short preganglionic and long?
post ganglionic axons
sympath ns has short ___________ and long ________________
short pregangl and long postganglionic axons
parasymp ns has long ?
long preganglionic ns
Parasym has short?
post gangl axons
what is presbyopia?
as you get older, the lens bec less elastic
as you get older your lens has a harder time "rounding up" this is called?
body has what 3 types of receptors?
interoceptors, propioceptors, and exteroeptors
interoceptors monitor?
inter envir like bl press, parti press of CO2 and bl ph
propioceptors monitor?
posit of body in space
where are propioceptors located?
muscles, tendons
what type of sensory receptor is in the inner ear?
exteroceptors sense what?
light, sound, taste, pain, touch, and temperat
eye is covered by a thick opaque layer called?
sclera (white of the eye)
what is beneatht the sclera of the eye?
choroid layer
choroid of the eye does what?
supplys retina w blood
The thick opaque layer of the eye is called?
What layer of the eye has photoreceptors?
what bends and focuses light?
after light is bent by cornea, it goes thr an opening called?
Iris does what?
controls the diameter of the pupil
The __________ contrls the diam of the pupil
t or f
iris is pigmented
What is suspended behind the pupil?
the lens
what contr the shape of the lens?
the ciliary muslces
the lens focuses the image on the ?
The retina has ?
Photoreceptors transduce ?
light into action potentials
2 types of photoreceptors?
cones and rods
cones are sens to ?
rods detect ?
low intensity light,
which photorecp is imp in night vision?
cones pigments absorb what 3 colors?
red, green and blue
what is the rod pigment?
photorecept cells-----> bipolar cells ----> ?
ganglion cells
right and left optic nerves are made up of?
bundles of axons of the ganglion cells
blind spot in eye is where?
the optic nerve exits the eye.
in the eye, the fovea has?
lots of cones
the fovea is import for
high acuity vision
where does the eye secrete aqueous humor?
near base of iris
aqueous humor travels to?
anterior chamber of the eye
lens of the eye is a ___________ lens
convex lens
the ear transduces?
sound energy (pressure waves)
ear does what 2 things?
1. transduces sound e
2. equil
outer ear is?
auricle (pinna)
auditory canal
tympanic membrane is at the end of?
auditory canal
middle ear is made up of?
tympanic membrane
what are the ossicles?
malleus, incus, stapes
what do the ossicles do?
amplify the stimulus and transm it thr oval window
oval window leads to?
fluid filled inner ear
inner ear consists of?
cochlea and semicircular canals
organ of corti is in?
the cochlea
organ of corti have what specialized sensory cells?
hair cells
when the ossicles vibrate it exerts pressure on?
fluid in cochlea, stim hair c to transduce press into act potentials
what do the hair cells do?
transd the press into action potent
action potent made by hair c are carried to brain by?
auditory nerve
whats the oth name for audit nerve?
cochlear nerve
the 3 semicirc canals are _________ to each other
the 3 semicirc canals are filled w?
what is at the base of each semicirc canal?
chamber w hair c
brain uses infor from semicirc canals to?
determ position of the head
the vestibulocochlear nerve is composed of?
cochlear and vestibular nerve
cranial nerve VIII is?
the vestibulocochlear nerve
chemical senses are?
taste and smell
gustatory and olfactory are?
taste and smell
taste buds are located on?
tonge, soft palate, and epiglottis
taste bud consists of?
40 epithelial c.
taste pore w microvilli or taste hairs.
what emerges from taste pore?
microvilli or taste hairs
gustatory infor travels to ?
brainstem thr 3 cran nerves
what are the four kind of taste sensations?
sour, salty, sweet, and bitter
taste buds resp preferentially to?
on of the four stimuli
olfactory recept have?
olfactory hairs or cilia
an odor cause the the olfact recept to?
olfactory nerves?
made up of axons from olfact recept
olfact nerves go to what part of the brain?
olfactory bulbs in the base of the brain
where are olfactory bulbs located?
in the base of the brain

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