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IPHY3280 > IPHY 3430 Exam 2 [Nervous] > Flashcards

IPHY 3430 Exam 2 [Nervous] Flashcards

1
Q

Nervous system

A
  • communication system
    -coordinates body function; electrical signals[graded potentials & action potentials]
    chemical signals; neurocrines[neurohormone, neurotransmitter, neuromodulators]
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2
Q

organization of NS

A
  • CNS
  • PNS: sensory[afferent] & motor[efferent; somatic division & autonomic division(sympathetic and parasympathetic branch)]
  • Enteric Nervous system(digestion)
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3
Q

Nervous system cells

A

neurons: basic signaling molecule

glial cells: provide support for neurons(many types of glial cells bu we focus on oligodendrocytes and schwann cells)

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4
Q

3 functional groups of neurons

A

afferent(sensory)
interneuron(there can be many or none)
Efferent (motor) neuron

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5
Q

Organization of a neuron

A

Dendrtite= input (receive incoming signals)
soma(cell body) = contains nucleus
trigger zone = “initial segement”; integration
axon = conduction(long distance); myelin and nodes of ranvier
Presynaptic (axon) terminal = output(talk to target cell)

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6
Q

Oligodendrocytes vs schwann cells

A

oligodendrocytes: form myelin in the CNS, wrap up to 15 axons
schwann cells: form myelin in PNS, wrap 1 axon

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7
Q

how are neurons connected? (labeled lines)

A

presynaptic cell: delivers signal at synapse

postsynaptic cell: receives signal at synapse

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8
Q

2 Electrical signals in neurons

A

Graded potential = local signals, purpose is to carry info from input region to trigger zone
Action potential = long distance signals, purpose is to carry info to presynaptic axon terminal

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9
Q

Integrative action

A

where there is both action and graded potentials

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10
Q

are electrical signals temporary changes in membrane potential?

A

yes, due to temporary (transient) changes in membrane permeability via gated ion channels.
- chemically-, mechanically- , voltage- gated.

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11
Q

Do electrical signals appreciably change ion concentrations ?

A

No, they do change separation of charge across the membrane(membrane potential)

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12
Q

Graded Potentials

A
  • originate in input region due to opening of gated channels

- decrease in amplitude(lose “strength”, “decay”) as travel

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13
Q

excitatory vs inhibitory

A

*Graded potentials can be both
excitatory- depolarize cell & make it easier to produce action potential
inhibitory- hyperpolarize cell & make it harder to produce action potential

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14
Q

different names for graded potentials

A

receptor potential: input region of sensory neuron
synaptic potential (Excitatory postsynaptic potential[EPSP], inhibitory postsynaptic potential [IPSP]): input region of interneuron and motor neuron
End-plate potential: input region of skeletal muscle

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15
Q

graded potential strength and duration

A

graded potentials vary in amplitude & duration to convey information about stimulus amplitude & duration.

  • amp: typically 0.1-10mV
  • duration: typically 2-10 msec
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16
Q

Where are graded potentials summated?

A

Graded potentials travel to trigger zone (integrative

site) & summate.
- typical neuron receives ~1000-10,000 inputs
- decision: action potential

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17
Q

integration at trigger zone from graded potential

A

determines whether action potentials produced & information is passed along

  • action potential threshold [subthreshold, suprathreshold]
  • both action and graded potentials at trigger zone(transition from local to long distance)
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18
Q

Purpose of action potentials

A

carry info from trigger zone to synapse(presynaptic terminal)
- log distance; dont decrease in amplitude(strength as propagate, “regenerated”
all-or- none(summate)- decisions been made.
typically ~1ms,~100mV but can vary based on ion flow.

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19
Q

how to Action potentials convey info?

A

Frequency: codes for stimulus amplitude (intensity,strength)
Duration of spike train: codes for stimulus duration

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20
Q

How are action potentials produced

A

Gated ion channels; produced by sequential opening & closing of voltage -gated ion channels.
- you need to let it rest before you try and produce another action potential, can’t summate

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21
Q

Gated ion channels for action potentials

A

Hodgkin-Huxley channels:
H-H Na+: closed(resting), open, inactive(refractory)
- time dependant
H-H K+ : closed, open

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22
Q

Action potential threshold

A

Action produced when trigger zone is depolarized above threshold because of positive feedback, Na+ comes in and tries to depolarize into its equilibrium potential.

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23
Q

Similarities between Na+ and K+ channels

A

differences: time responds to stimulus, reason ion stops flowing, # gates- inactivation- time(~1 msec)
similarities: voltage dependant; depolarize (~15-20mV) -> open - repolarize -> closed

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24
Q

Termination of positive feedback cycle

A

Two processes to repolarize cell

1) inactivation of voltage - gated Na+ channels
2) opening of voltage- gated K+ channels

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25
Q

Refractory periods

A
  • not all channels reset at the same time
    Absolute refractory: when there is no chance to summate an action potential
    relative refractory period: some channels are ready but some are not, you can get a small action potential. Na+ channels are time dependant so not all of them are ready,
  • to produce full action potential it takes about 2 msec
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26
Q

Action potential propagation

A

like dominos, the same action potential does not move, it just triggers the next one
- voltage- gated Na+ channels open & Na+ flows in, depolarizing that part of the axon; passive current flow depolarizes neighboring region[like water flowing along a pipe]

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27
Q

Speed of action potential

A

2 mechanisms increase conduction velocity.

  • diameter of axon; the bigger the faster
  • myelination, prorogations are faster when there is myelin on that section. Nodes of ranvier have teh ion channels so it is slower on those portions
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28
Q

saltatory conduction

A

myelinated axons

- nodes of ranvier; no nodes, where voltage gated channels and regeneration of action potential happens

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29
Q

how do action potentials convey info to synapse

A

action potentials propagate unfailingly over long

distances to output region (synaptic/axon terminal)

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30
Q

types of synapses

A

electrical: gap junctions, synchronize activity, rapid bidirectional signal conduction
Chemical: majority of synapses, most neurotransmitters stored in vesicles &exocytosed due to action potential [neurotransmitter diffuses across synaptic cleft.], slower but more flexible & allows amplification

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31
Q

purpose of action potential

A

open voltage gated Ca++ channels for exocytosis.

- uses hydrogen ion gradient and uses it as secondary active transport for exocytosis.

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32
Q

Neurotransmitter/ neurocrine secretion

A

-Release of neurotransmitter/neurocrine depends on frequency of action potentials, & duration of spike train
-Major neurocrines of peripheral nervous system (PNS):
acetylcholin(ACh), norepinephrine (NE), epinephrine (E)

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33
Q

types of postsynaptic receptors

A

nicotinic, muscarinic, AchR
- 2 types:
ionotropic (directly gated, channel protein)
• metabotropic (indirectly-gated, GPCR/RE)
- response maybe be excitatory or inhibitory
• EPSP/IPSP – excitatory/inhibitory post-synaptic potential
EPSP: depolarization (Na+)
IPSP: hyperpolarization (Ca++)

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34
Q

Termination of neurotransmitter activity

A

inactivate, reuptake, diffuse away. pump out Ca++

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35
Q

Afferent Division of PNS

A

Detects, encodes & transmits signals about internal & external environment to CNS

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36
Q

sensory receptors

A

classified based on nature of stimulus(type of energy) that receptor responds to & transduces

37
Q

types of senses

A

special senses, somatic senses, visceral senses

38
Q

special sense

A

have specialized organs devoted to them: eye, ear, nose, tongue; taste, vision, hearing, equilibrium, smell.

39
Q

somatic senses

A

somatosensory receptors - collect information from surface of
body (cutaneous sensations), and muscles & joints
(proprioceptive sensations => body position)
• cutaneous: touch, pain, skin temperature
• proprioception: e.g., muscle length & force, joint position

40
Q

visceral sense

A

• interoceptors sense/detect stimuli within internal organs
(viscera) such as blood vessels, gut, etc.
• e.g., chemoreceptors, baroreceptors, osmoreceptors
• monitor internal environment, e.g., blood glucose, blood
osmolarity, blood pressure, internal temperature

41
Q

phasic vs, tropic receptors

A

Phasic: rapid adapting, on off cells, don’t tell you how long something has been on/off for. just tells you something is on/off
Tonic: slowly adapting, stays active throughout the entire time of stimulus

42
Q

Receptive fields

A

Region w/in which a sensory neuron sense a stimulus: how you keep track of where signal came from.

43
Q

Sensory transduction

A

Stimulus alters receptor cells permeability leading to a graded potential
- transduction occurs via : ionotropic and metabotropic channels

44
Q

ionotropic channels

A

directly gated: mechanical, chemical, voltage

45
Q

Metabolic channels

A

indirectly gated: GPCR, receptor enzyme.

46
Q

Tastant transduction: why don’t we get confused on what flavors are which?

A

each taste cell only sense one type of ligand: salt, sour, bitter, sweet, or umami
G-protein: metabotropic[bitter, sweet, umami, fat]
tastant: transducing channels, ionotropic[salt(NA+), sour(H+)

47
Q

spinal cord organization for afferent signals.

A

spinal cord is organized to keep track of information
-somatotopy: “body map”
Sensory spinal cord: dorsal root, dorsal horn[ somatic, visceral]

48
Q

Decussation

A

“crossover”
sensory info decussates (crosses over) to other side of nervous system
• “upper” medulla: fine touch, proprioception, vibration
-dorsal column-medial lemniscus tract
• “lower” spinal cord: nociception (pain), temperature, coarse touch
- anterolateral tract

49
Q

Thalamus

A
  • relay station - (with exception of olfaction)

* many nuclei – each for one type of sensory information

50
Q

Somatosensory organization

A

Somatosensory projections from body maintain body map

  • CNS integrates sensory information
  • highest sensory signals when we are born come from the mouth and hands, so that takes a big part of the min-body map
51
Q

Brain areas

A 
CEREBELLUM
FOREBRAIN:
- cerebrum
------cerebral cortex; frontal lobe, parietal, occipital, temporal, 
------basal nuclei (voluntary movement)
-diencephalon; hypothalamus, thalamus
BRAIN STEM
- medulla oblongata
- pons
- midbrain[eye movement]
52
Q

Autonomic control centers

A

Hypothalamus: receives visceral sensory inputs & control autonomic sys, temp control, water balance, eating behavior
Pons & medulla: control autonomic sys (ANS) output to periphery; bladder control, sec respiratory control, BP, respiratory center

53
Q

Cerebellum

A

muscle(voluntary movement)

54
Q

where is sensory information processed?

A

cerebral cortex

  • parietal lobe: info from skin, musculoskeletal system, viscera, and taste buds
  • frontal lobe: coordinates info from other association areas, controls some behaviors
  • temporal lobe: auditory association area, taste and smell
  • occipital lobe: vision
55
Q

Efferent (motor) divisions

A

somatic and autonomic

56
Q

what part of the brain controls somatic motor neuron?

A

Motor cortex; then descends spinal cord

  • corticospinal tracts: most cross (decussate)at medulla(pyramidal tract)
  • somatotopy maintained
57
Q

what does somatic motor division control?

A

SKELETAL MUSCLE
somatic (alpha) motor neurons
• control skeletal muscle contractions (mostly voluntary)
• tonic
• neuron originates in CNS (ventral horn)
• leave ventral horn via ventral root to synapse onto skeletal muscle

58
Q

Neuromuscular junction

A

somatic(a) motor neuron releases acetylcholine
- always excitatory
Skeletal muscle fiber membrane (sarcolemma) contain nicotinic acetylcholine receptors (nAChR)

59
Q

end plate potential

A

Binding of acetylcholine (ACh) to nicotinic receptor
(nAChR) opens ion channels leading to depolarization of muscle membrane
- excitatory (Na+)
** graded potential = end plate potential

60
Q

Events at Neuromuscular junction

A

End-plate potential causes voltage-gated Na+ channels to open in muscle membrane (sarcolemma) leading to muscle (sarcolemmal) action potential …. ->muscle contraction

61
Q

Life cycle of acetylcholine at neuromuscular junction

A

acetyltransferase(enzyme)

  • acetyl CoA & choline
  • acetyl CoA comes from citric acid cycle
  • choline comes from diet(recycled)
62
Q

Termination of acetylcholine pathway

A

Acetylcholinesterase (AChE)

- breaks it down to acetate and choline

63
Q

Neurocrine Naming

A

Need to differentiate cell that makes & releases
signal versus cell that has receptors for signal
examples:
• cholinergic (relates to acetylcholine)
• cholinergic neuron – makes & releases acetylcholine as signal
• cholinergic receptor – binds & responds to acetylcholine
• subtypes: nicotinic, muscarinic
• adrenergic (relates to epinephrine/norepinephrine)
• adrenergic neuron - makes & releases E / NE as signal
• adrenergic receptor – binds & responds to E / NE
• subtypes: alpha, beta
• dopaminergic, serotonergic, GABAergic, glycinergic,
histaminergic, glutamatergic,….

64
Q

what does Autonomic neurons control?

A 
Control
- cardiac & smooth muscles
- many glands
- lymphoid & some adipose tissue
Mostly involuntary
- regulate/influence visceral functions
65
Q

Autonomic Division branches

A

Parasympathetic and sympathetic
Most effectors connected to both
branches (antagonistic control)
• excitatory & inhibitory effects (unlike somatic branch)
• act simultaneously
• shifts in predominance due to mental & physiological states
• autonomic tone* (background activity; balance between 2 branches)

66
Q

Autonomic Nervous system

A

creates autonomic, endocrine, & behavioral responses
- influenced by: cerebral cortex, limbic system
works closely w/ endocrine system to maintain homeostasis

67
Q

Antagonistic control of autonomic NS

A

Most internal organs are under antagonistic control.
Exceptions - only innervated by sympathetic
branch (tonic)
• (sweat glands)
• smooth muscle of most blood vessels

68
Q

Autonomic pathways consist of…

A

All autonomic pathways consist of 2 neurons in series
2 neurons that synapse in an autonomic ganglion
CNS -> preganglionic neuron -> autonomic ganglion (mini- integrating center) -> postganglionic neuron -> target tissue

69
Q

2 autonomic neuron pathways

A

sympathetic ganglia and parasympathetic ganglia

70
Q

sympathetic ganglia

A
  • close to spinal cord
  • short preganglionic neurons
  • thoracic & lumbar segments
  • long postganglionic neurons
71
Q

parasympathetic ganglia

A
  • vagus nerve is major tract: contains ~75% of fibers
  • located primarily on or near target organs
  • long preganglionic neurons
  • brain stem & sacral region
  • short postganglionic neurons
72
Q

ANS: Neurotransmitters and receptors

A

receptors: cholinergic [ nicotinic and muscarinic ] and adrenergic [ alpha and beta ]
- sympathetic pathways use CNS -> acetylcholine release from preganglionic neuron -> nicotinic receptor on autonomic ganglion-> norepinephrine released from postganglionic neuron -> target cell.
- parasympathetic use CNS ->preganglionic neuron -> acetylcholine -> nicotinic receptor on autonomic ganglia -> Acetylcholine released from postganglionic neuron -> GPCR

73
Q

Varicosities

A

where autonomic post ganglionic neurons end. It contains neurotransmitter & release it over the surface of the target cell

74
Q

Life cycle of norepinephrine at sympathetic neuroeffector junction

A

neuro effector junction: catecholamines are derived from tyrosine(amino acid) -> pump norepinephrine into vesicles by secondary active transport -> the rest is the same as the neuromuscular junction

75
Q

pancreas and the ANS

A

Pancreas is innervated by both branches, para and sympathetic.
Parasympathetic: increases activity due to food in digestive tract
- insulin secretion via IP3-Ca++ pathway [ feedforward response]
Sympathetic : inhibits the insulin secretion by decreasing cAMP
- effect; increased blood glucose available to fuel muscle activity for fight or flight

76
Q

Arterioles: receptor type determination

A

alpha and Beta adrenergic receptors on arterioles:
- B2 receptors cause vasodilation- decreases cAMP
- a receptors cause vasoconstriction - activates PLC
certain organs during fight or flight with receives one of the responses, muscles will dilate, urinary will constrict

77
Q

what stays longer; epinephrine or norepinephrine?

A

Norepinephrine

78
Q

termination of Norepinephrine

A

diffuses away or use active transport to move it back into the cell it came from or neighboring glial cells

79
Q

Adrenal Medulla

A

a specialized neuroendocrine gland that secretes epinephrine into blood

80
Q

reflexes

A

involuntary responses triggered by a sensory stimulus

81
Q

classifications of reflexes

A
  • efferent division: somatic vs. autonomic
  • integrating region in CNS: spinal (spinal cord) vs. cranial (brain)
  • time develops: innate (born - e.g., patellar tendon) vs. learned (conditioned) (acquired thru experience - e.g., Pavlov’s dog)
  • number of neurons: monosynaptic vs. polysynaptic
82
Q

Autonomic reflexes

A 
involve autonomic neurons & targets (internal organs)
ex: • urination/defecation
• salivating
• vomiting
• sneezing
• coughing
• swallowing
• gagging
• blushing
• heart rate
• blood pressure
****THEY CAN BE LINKED TO EMOTION[ GUT FEELING, BUTTERFLIES IN STOMACH]
83
Q

Skeletal reflexes

A

involve proprioceptors & somatic motor neurons
spinal reflexes:
• CNS integrates input signal
• mono- or polysynaptic pathways
• efferent neuron - somatic (alpha) motor neurons
• effectors - skeletal (extrafusal) muscle fibers
- mediated by Golgi tendon organ and muscle spindle organ

84
Q

Proprioceptors (skeletal muscle reflex)

A

• sensory receptors in skeletal muscle, joint capsules, & ligaments
• sense body position & change
non voluntary response, its a reflex

85
Q

Golgi tendon organ

A

monitors muscle force and mediates tendon reflex
- regulates muscle force,
- locates near the tendon
• innervated by sensory neuron (Ib afferent)
• mechanically-gated channels -> graded (receptor) potential

86
Q

Muscle spindle organ

A

monitors muscle length and mediates stretch reflex (patellar , knee jerk)
- regulates muscle length
- located within muscle fibers
• innervated by sensory neuron (Ia afferent)
• mechanically-gated channels -> graded (receptor) potential
Postural control!!!
Ex: patellar stretch reflex

87
Q

Golgi tendon reflex and muscle relaxation

A

this happens to prevent muscle damage, when there is too much force, the golgi relaxes the muscles.
polysynaptic pathway
• Ib afferent -> Ib inhibitory interneuron -> motor neuron

88
Q

Muscle tone

A

muscle spindles monitor muscle length

IPHY3280 (6 decks)

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