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Neurology > Phys 2 > Flashcards

Phys 2 Flashcards

1
Q

Small molecule neurotransmitters

-3 main groups

A
  • Amino acids- glutamate, GABA, glycine
  • Acetylcholine (ACh)
  • Monoamines- Norepinephrine (NE), Epinephrine (E), Dopamine (DA), serotonin
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2
Q

Large molecule neurotransmitters

-4 main groups

A
  • Substance P
  • Enkephalin
  • Endorphins
  • Releasing hormones such as TRH and LHRH
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3
Q

ACh is synthesized in the…

A

nerve terminal from choline and acetyl-coA by choline acetylcholase (ChAT)

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4
Q

ACh is transported into…

A

vesicles by vesicle associated transporter (VAT)

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5
Q

ACh is stored in…

A

vesicles in cholinergic fiber termini

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6
Q

ACh is released via… as a response to…

A

exocytosis as a response to calcium influx with axonal depolarization

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7
Q

Which complex enables ACh exocytosis?

A
  • SNARE complex enables exocytosis
  • SNAPS on cytosolic face of PM
  • VAMPS on vesicular membrane
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8
Q

Elimination of ACh from the synaptic cleft

A
  • ACh has a short 1/2 life
  • it is bound to post synaptic membrane
  • acetylcholinesterase comes in an hydrolyzes ACh into choline and acetate
  • choline and acetate can then be recycled or eliminated
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9
Q

Examples of cholinergic fibers are:

-5

A
  • Somatic motor neurons
  • ANS preganglionic neurons
  • PSNS postganglionic neurons

In CNS:

  • Basal forebrain complex (septal nuclei & nucleus basalis)
  • Pontomesencephalic cholinergic complex
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10
Q

ACh nicotinic receptors

  • location
  • action
A

location:

  • neuromuscular junction (Nm)
  • CNS and ANS ganglia (Nn)

action:

  • ligand-gated ion channels
  • 5 subunits surround a central channel
  • allows influx of cations (i.e. Na) which results in depolarization of the membrane: response is usually excitatory to cell
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11
Q

ACh muscarinic receptors

-location

A

-M1-M5 subtypes based on activity: all five are found in the CNS, while

M1-M3 are also found in various tissues

  • M1 AChRs: ANS ganglia and GI
  • M2 AChRs: cardiac tissue
  • M3 AChRs: smooth muscles and glands
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12
Q

ACh muscarinic receptors

-action

A

form G-protein coupled receptor (GPCR) complexes, you can think of this as a 2 messenger system:

  • the first messenger is a ligand that binds receptor causing conformational change
  • the second messenger utilizes a G-protein second messenger system
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13
Q

Activation of G-protein for ACh muscarinic receptors

A

the G protein binds GTP dissociating subunits for further signaling:

  • excitation or inhibition of adenylate cyclase to increase of decrease cAMP
  • phospholipase C activation which cleaves membrane bound PIP2
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14
Q

Membrane-bound PIP2 can be cleaved into…

A
  • IP3 (inositoltriphosphate): R on ER, release of Ca2+ to cytoplasm
  • DAG (diacylglycerol): which activates protein kinase C
  • PKC actions: contraction, vasoconstriction, secretion, etc.
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15
Q

ACh muscarinic receptor action

-M1, M2, M3

A

M1:

  • Gastric glands, excitatory
  • Phosphotidylinositol pathway

M2

  • Heart
  • Inhibitory to adenyl cyclase, decreasing cAMP

M3

  • Glands and smooth muscle, excitatory
  • Increase gastric motility and secretions
  • Phosphotidylinositol pathway
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16
Q

Norepinephrine synthesis

A
  • Tyrosine
  • DOPA
  • Dopamine is transported into vesicle
  • It is hydroxylated to form NE
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17
Q

Norepinephrine release

A
  • Depolarization of adrenergic fiber causes exocytosis of granules, releasing NE to synaptic cleft
  • NE has longer half life than Ach
  • Diffuses from cleft
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18
Q

Norepinephrine elimination

A
  1. Diffusion
  2. Binding postsynaptic membrane
    3, Catabolism
    for example by MAO
  3. Reuptake into presynaptic fiber
    –Accomplished by NET
    (NE transporter)
    –About 90% is reabsorbed
    –Located away from synapse
    –Removes diffused NE
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19
Q

Adrenergic fibers release…

A

Norepinephrine and epinephrine

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20
Q

The norepinephrine adrenergic fibers are:

A
  1. Postganglionic SNS fibers

2. Adrenal medulla

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21
Q

Norepinephrine adrenergic fibers

-adrenal medulla

A
  • Releases more E than NE
  • NE is transported out of vesicle
  • Methylated to form E
  • E is transported back to vesicle
22
Q

Adrenergic fibers - G protein coupled Receptors

-Alpha 1

A

Alpha1

  • Smooth muscle and heart
  • IP3 and DAG
23
Q

Adrenergic fibers - G protein coupled Receptors

-Alpha 2

A

Alpha2

  • CNS and pancreas
  • Inhibitory to AC (adenylate cyclase)
24
Q

Adrenergic fibers - G protein coupled Receptors

-Beta 1

A

Beta1

  • Heart, JGA
  • Activates AC (adenylate cyclase)
25
Q

Adrenergic fibers - G protein coupled Receptors

-Beta 2

A

Beta2

-Bronchial sm, myocardium, veins, GI organs, etc.

26
Q

Adrenergic fibers - G protein coupled Receptors

-Beta 3

A

Beta3

-Adipose

27
Q

Adrenergic receptors

-alpha 1 action

A
  • vasoconstriction
  • increased peripheral resistance
  • increased blood pressure
  • mydriasis
  • increased closure of internal sphincter of the bladder
28
Q

Adrenergic receptors

-alpha 2 action

A
  • inhibition of norepinephrine release
  • inhibition of ACh release
  • inhibition of insulin release
29
Q

Adrenergic receptors

-beta 1 action

A
  • tachycardia
  • increased lipolysis
  • increased myocardial contraction
  • increased release of renin
30
Q

Adrenergic receptors

-beta 2 action

A
  • vasodilation
  • slightly decreased peripheral resistance
  • bronchodilation
  • increased muscle and liver glycogenolysis
  • increased release of glucagon
  • relaxed uterine smooth muscle
31
Q

Interactions of Divisions - Antagonistic

A
  • Clearly seen in dual innervation systems (i.e. Heart, respiratory, and GI systems)
  • SNS increases HR, RR and decreases GI motility and secretions
  • PSNS decreases HR, RR and increases GI motility & secretions
32
Q

Interactions of divisions

-Sympathetic Tone

A
  • With few exceptions CVS is entirely innervated by SNS
  • Keep a continual partial contraction to maintain vasomotor tone
  • Can quickly respond for adaptation
33
Q

Interactions of Divisions

-parasympathetic tone

A

effects dominate the heart, smooth muscle of GI, and urinary tracts

34
Q

Interactions of divisions

-cooperative effects

A

Pupils

  • control of pupil diameter
  • SNS widens (mydriasis)
  • PSNS constricts (miosis)

External genitalia

  • PSNS erection
  • SNS ejaculation
35
Q

One division innervation via SNS seen in:

A
  • adrenal medulla
  • arrector pili muscles
  • sweat glands
  • kidneys (renin release, which increases vasoconstriction, blood volume, BP)
  • most blood vessels
36
Q

unique role of SNS

- thermoregulation (3)

A

Local heat to skin SNS creates local vasodilation.

Elevated systemic body temperature

  • -Widespread vasodilation to skin
  • -Skin flushes
  • -Dissipates heat

Depressed body temperature

  • -Widespread vasoconstriction of vessels to skin
  • -Shunts blood to core
37
Q

unique role of SNS

-metabolic effects (6)

A

-Either via direct innervation or increased adrenal medulla secretion of E
-Creates diffuse effects by circulating NE and E
Increased MR of body cells
-Increased blood sugar
-Mobilization of fats for fuel use
-Increased mental alertness by RAS stimulation

38
Q

What is the main integration center of ANS?

A

Hypothalamus

  • PSNS: medial and anterior hypothalamus
  • SNS: lateral and posterior
39
Q

The integration centers in the hypothalamus exert effects via…

A

the reticular formation which then stimulates preganglionic ANS motor neurons in brain stem and spinal cord

40
Q

What 6 things do the hypothalamus centers coordinate?

A
  1. Cardiac activity
  2. BP
  3. Body temp
  4. Water balance
  5. Emotional stages i.e. rage, pleasure
  6. Biological drives i.e. thirst, hunger, sex
41
Q

What has the most influence over ANS function?

A

Reticular formation of brain stem appears to have the most influence over ANS function

42
Q

What are the 2 arms of the reticular system?

A
  1. RAS (Reticular Activating System)

2. Reticular Formation Motor Arm

43
Q

RAS (Reticular Activating System)

  • projects to
  • receives
A

Projects widely to:

  • Hypothalamus
  • Thalamus
  • Cerebellum
  • Spinal cord

Receives sensory info to maintain arousal

44
Q
  1. Reticular Formation Motor Arm

- characteristics

A

-Somatic to cerebellum for tone and coordinated skeletal movements

Autonomic motor centers:

  • Vasomotor center-medulla
  • Cardiac center-medulla
  • Respiratory center- pons and medulla
45
Q

What reflex arcs does the brainstem receive info from?

A

from the reflex arcs for defecation and micturition

46
Q

Where is the oculomotor reflex?

A

In the midbrain

47
Q

Enteric nervous system

-location

A

Located in wall of digestive tract from esophagus to anus

48
Q

Enteric nervous system

-afferents

A

Receptors in mucosa sense chemical, mechanical, osmotic changes

49
Q

Enteric nervous system

-motor

A

Controls motility, arteriole diameter, secretion and absorption

*ANS nerves connect ENS to CNS to allow for coordination

50
Q

What are the 2 neural plexuses of the ENS?

A
  1. Myenteric (Auerbach’s) plexus

2. Submucosal (Meissner’s) plexus

51
Q

Myenteric (Auerbach’s) plexus

  • location
  • control
A
  • Located in between long and circular smooth muscle layers

- Controls motility

52
Q

Submucosal (Meissner’s) plexus

  • location
  • regulates
A
  • Located between circular muscle and luminal mucosa

- Regulates GI blood flow

Neurology (11 decks)

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