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psl201: physiology > week 6 > Flashcards

week 6 Flashcards

1
Q

is the ANS the afferent of efferent nervous system?

A

efferent

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2
Q

whats the primary function of the ANS? and what are the two divisions of the ANS that help achieve this goal?

A

primary function = maintain homeostasis

two divisions = parasympathetic and sympathetic

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3
Q

very briefly, what are the roles of the parasympathetic and sympathetic nervous systems?

A

parasympathetic = rest and digest

sympathetic = flight or flight

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4
Q

what is dual innervation?

A

the fact that BOTH divisions of the ANS innervate most effector organs

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5
Q

what are the two types of neurons from CNS to effector organs? what structure facilitates communication bw these neurons?

A

preganglionic and postganglionic neurons

autonomic ganglia

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6
Q

T or F: the soma of the preganglionic neuron sits in the PNS

A

false – sits in CNS

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7
Q

T or F: all adrenergic receptors are G-protein linked receptors

A

true!

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8
Q

what is the neurostransmitter associated with:
a) (para and sympa) preganglionic neurons

b) para postganglionic neurons
c) sympa post ganglionic neurons

A

a) acetylcholine (+ sometimes epinephrine for sympa)

b) acetylcholine
c) norepinephrine

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9
Q

SYMPA: preganglionic neurons emerge from ____ region of spinal cord, originate in a region of gray matter called the ___ or the _______.

A

thoracic/upper lumbar

lateral horn or the intermediolateral cell column

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10
Q

what is the sympathetic chain?

A

links sympathetic system to organs (short axons for pre neurons, long axons for post neurons)

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11
Q

PARASYMPA: pre neurons originate from _____ spinal cord.

A

brainstem/sacral

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12
Q

what is the parasympathetic chain

A

no such thing!
instead: have very long pre neuron, synapsing with post neuron in autonomic ganglia near effector organ.

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13
Q

what is a neuroeffector junction?

A

junction bw postganglionic neuron and effector organ

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14
Q

where are neurosransmitters stored in neuroeffector junctions

A

vesicles inside varicosities

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15
Q

T or F: one axon has several varicosities and releases neurotransmitter from ALL

A

true

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16
Q

describe the events occurring at the neuroeffector junction (6)

A
  1. AP arrives at varicosity.
  2. VGCC open.
  3. Ca2+ triggers exocytosis of neurotransmitter.
  4. neurotransmitter binds with receptors on effector organ.
  5. response in effector organ occurs.
  6. neurotransmitter is degraded and diffuses away; reuptake occurs.
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17
Q

___ in parasympathetic activity are coupled with ___ in sympathetic activity (and vice versa).

A

increases
decreases
(always opposites)

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18
Q

what kind of physiological activity takes place due to parasympa system? (3)

A
  1. increased gastrointestinal activities
  2. decreased heart rate
  3. decreased BP
19
Q

what kind of physiological activity takes place due to sympa system? (6)

A
  1. increased heart rate
  2. increased BP
  3. mobilizes energy stores
  4. dilates pupils
  5. decreases gastrointestinal/urinary functions
  6. releases epinephrine
20
Q

where does the sympa system release epinephrine from?

A

adrenal medulla

21
Q

what are MAOIs? (3)

A
  • powerful antidepressants that increase amount of norepinephrine by reducing its degradation.
  • also acts in PNS… therefore, see increased heart rate and other symptoms.
  • often reserved as last resort for these reasons.
22
Q

at rest, which system dominates?

A

parasympa

23
Q

why do autonomic/visceral reflexes occur?

A

bc ANS is linked to the sensory system to produce functional reflexes. these are negative feedback loops that aim to maintain homeostasis (full bladder example)

24
Q

pick an example of an autonomic reflex and describe how it works

A
  • pupillary light refllex
  • too bright = parasympa reflex to circular muscles (constriction)
  • too dark = sympa reflex to radial muscles (dilation)
25
Q

what is baroreflex?

A
  • maintainence of BP at constant levels.
  • ex. decreased BP will cause heart rate to increase to restore BP.
  • controlled by ventrolateral medulla and muscle sympa effects (noradrenergic vasoconstriction).
26
Q

areas of the brain that regulate autonomic function (3)

A

medulla
hypothalamus
pons

26
Q

efferent neurons of somatic nervous system are aka…

A

motor neurons!

26
Q

describe the parasympa vs sympa effects for:
a) heart
b) urinary bladder
c) skin

A

a) parasympa: decreases everything, sympa: increases everything

b) parasympa: wall contracts/sphincter relaxes, sympa: wall relaxes/sphincter contracts

c) both make sweat glands secrete, but only sympa makes hairs stand up (piloerector muscles)

27
Q

what is a neuromuscular junction?

A

the synapse between a motor neuron and a muscle fiber

28
Q

what are the neuromuscular junction equivalents for axon terminals?

A

terminal bouton

29
Q

what is the motor end plate

A

specialized muscle membrane at junction (where motor neurons end)

30
Q

T or F: all motor neurons release serotonin and are inhibitory?

A

false!!!
acetylcholine
excitatory

31
Q

which toxins result in muscle spasms? which toxins result in muscle paralysis?

A

spasms = latroxin (black widow venom)

paralysis = crotoxin (rattlesnake venom) and curare.

32
Q

activation of motor neuron depends on _____

A

summation of EPSPs/IPSPs

33
Q

describe the events occurring at the neuromuscular junction (8)

A
  1. AP arrives at terminal bouton.
  2. VGCC open.
  3. Ca2+ enters cell triggering release of ACh.
  4. ACh diffuses across cleft and binds to nicotinic receptors on motor end plate.
  5. ACh triggers opening of channels for small sodium and potassium cations.
  6. depolarization.
  7. AP in muscle cell.
  8. AP spreads thru muscle causing contraction.
34
Q

describe crossbridge cycle process (5)

A
  1. actin binds to myosin (Pi released)
  2. power stroke
  3. rigor (myosin in low-energy form, ADP released)
  4. unbinding of myosin and actin (ATP required/hydrolisized)
  5. cocking of myosin head (myosin in high-energy form)
35
Q

what is excitation-contraction coupling?

A

sequence of events whereby an AP in the sarcolemma causes contraction.

  1. ACh binds to motor plate, eliciting AP in muscle cell.
  2. AP propagates along sacrolemma.
  3. AP triggers Ca2+ release.
  4. Ca2+ binds to troponin, exposing myosin-binding sites.
  5. crossbridge cycle begins.
  6. Ca2+ transported back
36
Q

how is contraction terminated?

A

Ca2+ leaves binding sites via ATPase (pump) which moves it to sarcoplasmic reticulum

37
Q

T or F: a twitch is an all-or-nothing event

A

true

38
Q

phases of muscle twitch (3)

A

LATENT PERIOD = muscle excited… AP spread through muscle and calcium released, but has not arrived yet

CONTRACTION PHASE = intracellular calcium levels increase; more crossbridges forming.

RELAXATION PHASE = calcium pumped back into SR. intracellular calcium level falls. fewer crossbridges.

39
Q

what is tetanus? what muscles does this occur in?

A

APs fire so close you get fused tetanus (maximum force reached). occurs only in skeletal muscles; not cardiac

40
Q

parasympathetic system:

A
  • pre AND post neurons release ACh
  • post neurons have nicotinic ACh receptors
  • effector organs have muscarinic ACh rceptors
41
Q

sympathetic system:

A
  • pre neurons release ACh… note: can also release ACh directly onto receptors of adrenal gland, which then release E
  • post neurons have nicotinic ACh receptors
  • post neurons release NE
  • effector muscles have adrenergic NE receptors

psl201: physiology (21 decks)

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