PCAT > Nervous system > Flashcards

Nervous system Flashcards

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1
Q

nervous system

A
  • receive and respond to stimuli from their internal/external environments
  • composed of neurons and neuroglia
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2
Q

neuron

A
  • specialized nervous tissue used to convert stimuli into electrochemical signals
  • dendrites, cell body, and axons
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3
Q

cells in the CNS

A

-astrocyctes, oligodendrocytes, microglia, ependymal cells

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4
Q

astrocytes

A

-maintain the integrity of the BBB, regulate nutrient and dissolved gas concentrations, and absorb/recycle neurotransmitters

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5
Q

oligodendrocytes

A

myelinate CNS axons and provide structural framework

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6
Q

microglia

A

remove cellular debris and pathogens

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7
Q

ependymal cells

A

-line brain ventricles and aid in production of CSF

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8
Q

satellite cells

A

surround the neuron cell bodies in the ganglia

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9
Q

Schwann cells

A

enclose the axons in the PNS and myelinated some peripheral axons

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10
Q

Schwann cells

A

enclose the axons in the PNS and myelinated some peripheral axons

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11
Q

resting potential

A

-even at rest, a neuron is polarized due to unequal distribution of ions b/w the inside and outside of the cell, -70mV (inside is more negative than outside)

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12
Q

Na+/K+ pump

A
  • pumps 3 Na+ out of the cell for every 2 K+ it transports in, causes negative internal environment
  • cell membrane is permeable to K+ allowing some to move back out thru facilitated diffusion, making the inside even more -
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13
Q

action potential

A

-if the cell becomes sufficiently excited and depolarized (less negative) to reach the threshold potential, then voltage-gated channels open in response

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14
Q

an action potential begins when:

A
  • voltage-gated Na+ channels open in response to depolarization
  • Na+ rushes into the cell causing more depolarization
  • action potential moves down the terminal until it reaches the synaptic terminal, where Ca2+ channel is opened and triggers the exocytosis of synaptic vesicles
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15
Q

after the signal has been propagated thru a segment of the axon…

A
  • voltage-gated K+ channels open and K+ rushes out of the cell
  • Na+/K+ pump begins to pump Na+ out of the cell
  • repolarization occurs
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16
Q

hyperpolarization

A

voltage shoots past the resting potential and becomes even more negative inside

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17
Q

refectory period

A
  • period of time after an action potential during which new action potentials are difficult to initiate immediately
  • helps ensure the action potential only moves forward
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18
Q

impulse propagation

A
  • occurs in one direction: dendritic to synaptic terminal

- different axons propagate at different speeds; greater the diameter, more it is myelinated, faster the impulse travels

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19
Q

synapse

A

gap b/w the axon terminal of one neuron (presynaptic neuron) and dendrites of another (postsynaptic neuron)

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20
Q

effector cells

A

neurons communicate with postsynaptic cells other than neurons, ex: muscles or glands

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21
Q

curare

A
  • blocks postsynaptic nicotinic acetylcholine receptors, on muscles
  • leads to muscle relaxation and paralysis
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22
Q

botulinum toxin

A
  • prevents release of acetylcholine from the presynaptic membrane
  • results in paralysis
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23
Q

anticholinesterases

A
  • inhibit the activity of acetylcholinesterase enzyme responsible for degrading acetylcholine released in the synapse
  • no coordinated muscle contraction can take place
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24
Q

afferent neurons

A

carry sensory info from environment to spinal cord

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25
efferent neurons
carry motor commands from the brain/spinal cord to various parts of the body
26
interneurons
participate only in local circuits, linking sensory and motor neurons
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ganglia
neuron cell bodies clustered together in the PNS
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CNS includes:
brain and spinal cord
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brain
-interpret sensory info, forms motor plans, and thinking
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grey matter
-outer portion of cell bodies in the brain
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white matter
-inner portion of myelinated axons
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forebrain (prosencephalon)
-consist of telencephalon and diencephalon
33
cerebral cortex
- highly convoluted grey matter - part of telencephalon - important for memory and creative thought
34
diencephalon
-thalamus and hypothalamus
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thalamus
-integration center for the spinal cord and cerebral cortex
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hypothalamus
-controls visceral functions such as hunger, thirst, sex drive, blood pressure, temp regulation
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midbrain
- relay center for visual and auditory impulses | - important in motor control
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hindbrain (rhombencephalon)
-consists of cerebellum, pons, and medulla`
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cerebellum
-helps modulate motor impulses initiated by cerebral cortex; balance, hand-eye coordination, and rapid movements
40
pons
-act as a relay center to allow the cortex to communicate with the cerebellum
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medulla
-controls breathing, HR, and gastrointestinal activity
42
spinal cord
- acts as. conduit for sensory info to the brain and motor info from the brain - integrates simple motor responses (reflexes) - outer white matter (axons), inner grey matter (cell bodies)
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dorsal horn
-where sensory info enters the spinal cord
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ventral horn
-motor info exists the spinal cord
45
PNS includes:
nerves and ganglia
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somatic nervous system
innervates skeletal muscles and responsible for voluntary movement
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autonomic nervous system (involuntary)
- regulates body's internal environment - innervates cardiac and smooth muscle - important in BP control, gastrointestinal motility, excretion, reproduction, and respiration
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sympathetic nervous system
- "fight or flight" - increase BP, HR, blood flow; decreases gut motility - uses norepinephrine as its neurotransmitter
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parasympathetic nervous system
- "rest and digest" - lower HR, increase gut motility - acetylcholine as its neurotransmitter
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vagus nerve
-parasympathetic nerve that innervates thoracic and abdominal viscera
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eye
-detects light energy and transmits info to the brain
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sclera
thick, opaque layer that covers the eyeball
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choroid
- beneath sclera | - supplies retina with blood
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retina
innermost layer of eye, contains photoreceptors that sense light
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cornea
at front of the eye, bends and focuses light rays
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iris
-responds to intensity of light in the surroundings (light makes pupils contract)
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lens
focuses the image onto the retina
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two main type of photoreceptors:
- cones: high-intensity illumination, sensitive to color | - rods: low-intensity illumination, night vision
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rhodopsin
rod pigments that only absorbs a single wavelength
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bipolar cells
-photoreceptor cells synapse onto this which then synapse onto ganglion cells
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blind spot
point at which the optic nerve exits the eye, no photoreceptors present
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fovea
small area of the retina above the blindspot, densely packed with cones
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vitreous humor
jelly-like material that helps maintain the shape and optical properties
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aqueous humor
watery substance that fills the space b/w the lens and cornea
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myopia (near sightedness)
occurs when the image is focused on the front of the retina
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hyperopia (farsightedness)
occurs when the image is focused behind the retina
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astigmatism
caused by an irregularly shaped cornea
68
cataracts
when lens become opaque, light cannot enter the eye
69
glaucoma
increase in pressure of the eye b/c of blocking of the outflow of aqueous humor
70
ear
tranduces sound energy (pressure waves) into impulses perceived by the brain as sound
71
outer ear
-consists of the auricle and the auditory canal
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tympanic membrane (eardrum)
- at the end of the auditory canal | - vibrates at the same frequency as the incoming sound
73
ossicles
- malleus, incus, stapes - amplify the stimulus and transmit it thru the oval window - vibration stimulates hair cells in the basilar membrane to traduce pressure into action potentials which travel via the cochlear (auditory) nerve
74
inner ear consists of:
-cochlea and vestibular apparatus, involved in equilibrium
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