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MCAT bio > Nervous System and Endocrine System > Flashcards

Nervous System and Endocrine System Flashcards

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1
Q

action potentials

A

electrochemical impulses that help cells transmit and process info from one part of the body to another

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2
Q

synaptic transmission

A

action potential being transformed into a chemical signal causing release of neurotransmitter into the synaptic cleft

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3
Q

neuron

A

basic functional and structural unit of the nervous system

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4
Q

synaptic cleft

A

small gap where chemical messengers travel across

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5
Q

resting membrane potential

A

created by Na+/K+ ATPase and potassium leak channels, causes cells to be polarized

Depolarization changes this potential and repolarization returns the potential to normal (-70)

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6
Q

depolarization

A

propagation of action potentials caused by voltage gated sodium channels allowing sodium ions to flow down their gradient into the cell

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7
Q

threshold potential

A

-50 mV, reached by opening of voltage gated sodium channels

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8
Q

repolarization steps

A

VG sodium channels inactivate very quickly, VG potassium channels open and potassium leaves cell, causing membrane potential to reach -90 mV

K+ leak channels and Na+/K+ ATPase also functioning to return membrane to resting potential

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9
Q

myelin

A

insulating sheath composed of Schwann cells, a type of glial cell. no membrane depolarization and no voltage gated sodium channels in regions of the axonal plasma membrane wrapped in myelin

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10
Q

saltatory conduction

A

rapid jumping of action potentials from node to node in myelinated cells

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11
Q

glial cells

A

specialized, non-neuronal cells that typically provide structural and metabolic support to neurons

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12
Q

equilibrium potential

A

where there is no net movement of ions across the membrane

Na+ has positive equilibrium potential and K+ has negative equilibrium potential

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13
Q

refractory period

A

when a cell can’t transmit another action potential, two different periods:

absolute refractory - neuron won’t fire another action potential no matter how strong a membrane depolarization is induced

relative refractory period - depolarization required is greater than normal because the membrane is hyperpolarized

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14
Q

steps for transmission of a signal across a chemical synapse in the nervous system

A
  1. action potential reaches end of axon
  2. Depolarization of presynaptic membrane opens voltage gated calcium channels
  3. Calcium influx into presynaptic cell causes release of NT stored in secretory vesicles
  4. NT diffuse across narrow synaptic cleft
  5. NT binds to postsynaptic receptors
  6. membrane polarization of postsynaptic cell changes
  7. Action potential in post synaptic cell initiates if depolarization of postsynaptic cell occurs
  8. Degradation of NT in synaptic cleft
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15
Q

Acetylcholine

A

neurotransmitter related at neuromuscular junction

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16
Q

excitatory vs inhibitory NTs

A

depolarizes postsynaptic membrane vs hyper polarizes postsynaptic membrane

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17
Q

summation

A

effect of all synapses on membrane potential measured by postsynaptic neuron to decide whether to fire an action potential, can be temporal (rapid firing of action potentials) or spatial (summing of EPSPs and IPSPs from all of the synapses)

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18
Q

efferent vs afferent neurons

A

carry info away from CNS vs carry info to CNS

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19
Q

reflex

A

sensory neuron transmits an action potential to a synapse with a motor neuron in the spinal cord

doesn’t involve brain

ex. knee jerk reflex where sensory neuron is activated that directly synapses with a motor neuron in the spinal cord, causing the quadriceps to contract

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20
Q

reciprocal inhibition

A

concurrent relaxation of one muscle and contraction of another

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21
Q

somatic vs autonomic systems

A

voluntary vs involuntary

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22
Q

parasympathetic vs sympathetic

A

parts of autonomic system

rest and digest vs fight or flight

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23
Q

grey matter vs white matter

A

unmyelinated neuronal cell bodies vs myelinated axons in CNS and PNS

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24
Q

CNS vs PNS

A

CNS - brain/spinal cord
PNS - includes all other axons, dendrites, and cell bodies

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25
Q

three subdivisions of the brain

A

hindbrain, midbrain, forebrain

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26
Q

what does the entire Brain float in

A

cerebrospinal fluid, which serves various functions in shock absorption and exchange of nutrients and waste

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27
Q

spinal cord function

A

pathway for info to and from the brain, processing and integration of info, primitive processes like walking, sex, and urination

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28
Q

hindbrain parts

A

medulla - controls autonomic processes such as blood pressure, blood flow, heart rate, swallowing
pons- connects spinal cord and medulla with upper regions of brain, controls balance
cerebellum - integrating center functioning in movement coordination

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29
Q

midbrain functions

A

responsible for arousal or wakefulness

30
Q

forebrain parts

A

diencephalon, telencephlon

31
Q

thalamus function

A

contains relay and processing centers for sensory info

32
Q

hypothalamus

A

primary link between nervous and endocrine systems, controls homeostatic functions like temperature regulation, fluid balance, and appetite

33
Q

corpus callosum

A

thick bundle of axons that connects cerebral hemisphere

34
Q

function of cerebral hemispheres

A

conscious thought processes and intellectual functions

35
Q

four lobes of cerebral cortex

A

frontal (voluntary movement), parietal (general sensations), temporal (auditory and olfactory sensation), occipital (visual sensation), involved in higher thought processes

36
Q

basal nuclei

A

found deep within cerebral hemispheres, function in voluntary motor control and procedural learning related to habits

37
Q

limbic system

A

located between cerebrum and diencephalon, important in emotion and memory

38
Q

cranial nerves

A

convey sensory and motor info to and from the brainstem

39
Q

vagus nerve effect

A

type of cranial nerve that decreases heart rate and increases GI activity

40
Q

What is true about the somatic system

A

all somatic motor neurons innervate skeletal muscle cells, use ACh as their neurotransmitter, and have their cell bodies in the brain stem or the ventral position of the spinal cord

all somatic sensory neurons have a long dendrite extending from a sensory receptor toward the soma, an axon extends from the somatic sensory neuron into the spinal cord

41
Q

anatomy of the autonomic system

A

preganglionic neuron has a cell body in the brainstem or spinal cord, which sends an axon to the autonomic ganglion, located outside the spinal column.

This axon synapses with the postganglionic neuron, which sends an axon to an effector.

42
Q

sympathetic vs parasympathic preganglionic soma locaction

A

sympathetic - thoracic and lumbar spinal cord
parasympathetic - brainstem and sacral spinal cord

43
Q

adrenal gland characteristics

A

includes inner medulla and outer cortex, part of sympathetic nervous system, releases epinephrine

44
Q

types of sensory receptors

A

mechanoreceptors - respons to mechanical disturbances such as pressure
chemoreceptors
nociceptors - pain receptors
thermoreceptors
electromagnetic receptors

45
Q

four properties of stimulus that need to be communicated to CNS

A
  1. type of stimulus
  2. location of stimulus
  3. intensity of stimulus coded by frequency of action potentials
  4. stimulation duration
46
Q

adaptation

A

decreases in firing frequency when the intensity of a stimulus remains constant

47
Q

proprioception

A

awareness of self (ex. awareness of body part position)

48
Q

gustation vs olfaction

A

taste and smell, rely on chemoreceptors

49
Q

ear structure

A

includes outer ear, middle ear, and inner ear

50
Q

mechanism of hearing

A
  1. sound waves enter external ear to pass into auditory canal, causing eardrum to vibrate
  2. malleus attached to eardrum receives vibrations
  3. vibrations passed to incus then stapes (middle ear)
  4. Vibration of oval window creates pressure waves in perilymph and endolymph, fluids in the cochlea.
  5. Basilar membrane vibration occurs through cochlea, causing dendrites form bipolar auditory afferent neurons to be stimulated
51
Q

What is the primary site at which auditory stimuli are detected

A

organ of Corti in the cochlea

52
Q

how is pitch distinguished

A

by which regions of the basilar membrane vibrate

53
Q

vestibular complex function

A

contains tubes filled with endolymph and contains hair cells that detect motion, important for balance

54
Q

direction of light in eye

A

cornea (bends/refracts light) to sclera to choroid to retina, the surface upon which light is focused.

55
Q

iris

A

colored part of eye, regulates diameter of pupil

56
Q

vitreous chamber

A

where light passes through en route from lens to retina

57
Q

rods and cones

A

synapse with bipolar cells ( cells with one axon and one dendrite)

rods function in night vision and cones are responsible for color vision and high acuity vision

58
Q

optic disk

A

blind spot, where axons from ganglion cells converge to form optic nerve, contains no photoreceptors

59
Q

opsin

A

bound to retinal, changes structure upon absorbing light

60
Q

role of glutamate in rods and cones

A

glutamate released onto bipolar cells during their depolarization and less is released during hyperpolarization

61
Q

on center vs off center bipolar cells

A

inhibited by more glutamate vs stimulated by more glutamate

on center cells are depolarized when light is shone directly on them

off center cells are depolarized when light is shone on surrounding areas (in the dark)

62
Q

parallel processing

A

many aspects of a visual stimulus are processed simultaneously instead of in a step by step or serial fashion

63
Q

absolute threshold

A

minimum stimulus required to activate a sensory receptor 50 percent of the time

64
Q

bottom up and top down processing

A

bottom up - begins with sensory receptors and works up to the complex integration of info occurring in the brain

top down - brain applies experience and expectations to interpret sensory info

65
Q

How are the nervous system and endocrine system connected

A

neurons can signal the release of hormones from endocrine glands

66
Q

endocrine gland

A

ductless gland whose secretory products are picked up by capillaries supplying blood to the region

67
Q

hydrophilic vs hydrophobic hormones

A

hydrophilic - bind to receptors on cell surface (ex. peptides)

hydrophobic - bind to receptors in cellular interior (ex. steroids)

68
Q

tropic hormones

A

hormones that regulate hormones (ex. adrenocorticotropic hormone)

69
Q

releasing/ inhibiting factors

A

released by hypothalamus to regulate other tropic hormones

70
Q

hypothalamic pituitary portal system

A

special miniature circulatory system provided for efficient transport of hypothalamic releasing and inhibiting factors to anterior pituitary

71
Q

anterior vs posterior pituitary

A

anterior - normal endocrine gland controlled by hypothalamic releasing/inhibiting factors

posterior - composed of axons which descend from hypothalamus

72
Q

thyroid hormone/ cortisol function

A

broad effects on metabolism and energy usage

MCAT bio (11 decks)

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