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Physiology Test 1 > Membrane Potential And Excitbility > Flashcards

Membrane Potential And Excitbility Flashcards

1
Q

Ca2+ outside vs inside cell

A

Ca2+ kept very low inside cell, and high outside cell
*** Ca2+ kept under severe control

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2
Q

Na-K Pump

A
  • uses ATP
  • 3 Na out
  • 2 K in

*** purpose/fn of Na|K ATPase is to establish Na|K gradient inside/outside the cell

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3
Q

Ca2+ Pump

A
  • requires ATP
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4
Q

Ca2+ used for:

A
  • conformational changes
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5
Q

Ohm’s Law

A

V=IR

I=VxG
Current = voltage x conductance

Amount of current you get = push (voltage) x how easy it is to go a->b (conductance)

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6
Q

Pores

A

Checks amino acids as filter

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7
Q

T|F At Nernst Potential there’s current for X ion?

A

F
- when at equilibrium, there is no current for the ion at equilibrium

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8
Q

Current can only occur when Voltage is

A

Different from NERST potential

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9
Q

Action Potential

A

Electrical signature responsible for all electrical activity in the body

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10
Q

Gating of Sodium Channels
(2 types)

A

M: ACTIVATION gate; opens
H: INACTIVATION gate; almost immediately closes; can’t open again until resets

  • transitions between resting, activated, and inactivated states are dependent on membrane potential and time
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11
Q

BEFORE AP

A
  • @ resting potential K+ at highest [inside], Na+ at highest [outside]
  • Na|K pumps use ATP to maintain these gradients across the plasma membrane
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12
Q

Resting State

A
  • more K channels open than Na
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13
Q

Depolarization

A
  • some Na channels open depolarize game the membrane
  • K channels are closed
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14
Q

Rising Phase of AP

A
  • nearly all Na channels open, sharply raising the AP towards Ena
  • K channels remain closed
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15
Q

Repolariziation

A
  • Na close, K open, pulling membrane potential towards Ek
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16
Q

Undershoot

A
  • overly depolarizes, pulling membrane potential towards Ek, past resting potential
  • Voltage-gated K channels close to restore RP
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17
Q

Going to + NERST
Going to - NERST

A

+: Na|Ca
-: MUST be K

Na\K resets everything

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18
Q

Heart AP

A

AP held longer because Ca2+ helps hold K in

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19
Q

Catecholamines

A

Increase pacemaker rate by increasing cAMP which opens HCN channels increasing If sodium current during phase 4. That increases the slope of phase 4 thus the rate

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20
Q

CNS Overview

A

Brain & Spinal Cord
Afferent Division: sensory stimuli; visceral stimuli : input to CNS from periphery
Efferent Division: autonomic NS; somatic nervous system
Autonomic NS: sympathetic; parasympathetic NS : smooth|cardiac muscle; exocrine|endocrine glands
Somatic NS: motor neurons; skeletal muscle

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21
Q

Where is the ANS controlled?

A
  • controlled centrally in brain regions including hypothalamus, midbrain, pons, medulla
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22
Q

ANS
Function|innervates

A

Function: Involuntary: sympathetic; parasympathetic; enteric
Innervates: cardiac muscles; smooth muscles; glandular epithelia

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23
Q

Somatic Motor Neuron

A
  • originates from spinal cord
  • directly innervates skeletal muscles
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24
Q

Autonomic Motor Neurons

A

-Preganglionic neuron ( most are myelinated): cell bodies in spinal cord
- postganglionic neuron (unmylinated): cell bodies in autonomic ganglia

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25
Parasympathetic NS
- ganglion located close to target organ - sympathetic chain ganglion: located in two sympathetic chains running alongside spinal cord - short pre; v. Long post
26
Ganglion (Sympathetic Chain)
- located in two sympathetic chains running alongside spinal cord - short pre, very long post
27
Sympathetic Subdivision also includes:
Innervation of adrenal medulla, which then secretes epi & norepi which are important for flight|flight reponse
28
Adrenal Medulla
Regulates release of epi|norepi
29
Ganglion
Intermediate before target organ
30
Reciprocal functions of the sympathetic|parasympathetic actions on the heart
- each target organ is reciprocally regulated by both symp|parasymp systems
31
Sympathetic Ganglia of the Heart
- located in symp chain
32
Parasymp ganglia are located (Cardiac plexus)
Close to the target organ
33
SA node & AV node are innervates by
Both parasymp|symp systems
34
Dual innervation by symp|parasymp systems to target organs allows for
Balanced regulation of physiological functions
35
2 pathways originating from the hypothalamus important for body’s stress response
- sympatho-adrenal axis: releases epi|norepi = adrenaline rush during fight|flight - HPA axis
36
Enteric Nerbous System inputs
Symp & parasymp
37
Enteric NS composed of
- local neural networks that receive inputs from both symp|parasymp systems
38
Enteric NS includes
- submucosa plexus - myenteric plexus
39
Submucosal Plexus
Enteric NS - groups of neurons located in submucosa of GI tract
40
Myenteric Plexus
Enteric NS - groups of neurons located between 2 smooth muscle layers of GI tract
41
The ANS includes
- sympathetic and parasympathetic divisions
42
The sympathetic division mobilizes the body for ___________ and controls the _________
- mobilizes the body for activity - controls the “fight|flight” response
43
The sympathetic system also innervates the ___________ ___________, which secretes...
- innervates the adrenal medulla - which secretes epi|norepi important for the fight|flight response
44
The parasympathetic division...
- relaxes the body; rest|digest
45
Ying|Yang Regulation
Symp|parasymp
46
The Enteric NS contains the _______ & _____ and is controlled by both the ________ & __________ divisions
- myenteric plexus & submucosal plexus - sympathetic|parasympathetic divisions
47
Wiring the autonomic NS
- reiprocal regulation between symp|parasymp
48
2 main synapse types:
- electrical: faster - chemical: allow for more levels of regulation by using diff NT & different receptors
49
Electrical Signals
- v. Fast (cardiac)
50
Trafficking Pathways in the Nerve Terminal
- precursors of synaptic vesicles get loaded with neurotransmitters, then dock at active zone and become primed to be released in response to an action potential - vesicles undergo endocytosis to be recycled & reused - pre-synaptic vesicles loaded with NT; AP releases vesicles into space - recycle vesicles back in after signal completion
51
NT vs Hormone
NT: acts locally at the synapse Hormone: released into blood and can affect distant organs Some substances can be both (norepi)
52
What defines a neurotransmitter?
- must be present in the presynaptic neuron - must be released in response to presynaptic depolarization - specific receptors for the substance must be present on the postsynaptic cell
53
Neurotransmitter
- substances synthesized in the presynaptic neuron (MUST be present in presynaptic neuron) - released in response to an AP - act on specific receptors on postsynaptic cells
54
NT Important for peripheral NS
- Acetylcholine - Norepi
55
3 Catecholamines
- adrenaline - noradrenaline - dopamine
56
NT release at the synaptic terminal
- NT release is in response to an AP which triggers Ca2+ influx
57
Chemical Synapse effect on time
- process of synaptic transmission at the chemical synapse causes a slight time delay
58
What is significant about the delay with chemical synapses
Acts as regulation
59
2 Broad Types of Postsynaptic Receptors
- ionotropic - metabotropic: regulate target response through secondary messenger pathways
60
Ionotropic Rececptor
- Nicontinic - all postganglionic neurons; adrenal medullary cells and neuromuscular junctions of the skeletal muscle: causes excitation
61
Nicotinic Acetylcholine Receptors (NAchR)
- specifically activated by nicotine - IONOTROPIC - permeable to Na|K (and sometimes Ca)
62
Nicotine Poisoning - where receptors are located - what can nicotine affect
- nAchRs: located on skeletal muscles, post ganglion is neurons & adrenal medullary cells - nicotine can affect the somatic, symp|parasymp NS depending on dosage - e cigs can cause nicotine poisoning
63
Metabotropic Receptors
- GPCR signaling pathways: can lead to different downstream pathways depending on specific G proteins bound to the receptors
64
Muscarinic Acetylcholine Receptors (MAchRs)
- Metabotropic - have different subtypes: can activated different downstream pathways depending on which Gproteins bound - mainly expressed on target organs of parasympathetic pathways
65
mAchRs - agonist vs antagonist
- agonists will mimic the actions of the parasympathetic system - antagonists will inhibit the parasympathetic system
66
Parasympathetic System Overall Effect
- decreased heart rate - decreased BP - increased digestion - contracts bladder wall muscles Rest|Digest
67
Adrenergic Receptors
- all activated by epi|norepi - lead to diverse intracellular signaling pathways
68
Types of Adrenergic Receptors
- a1: smooth muscle contraction - a2: inhibition of transmitter release; smooth muscle contraction -B: heart muscle contraction; smooth muscle relaxation; glycogenolysis
69
Adrenergic Receptor Antagonists
- mainly expressed in sympathetic target organs - will counter the action of the sympathetic system - NE
70
Somatic NS (illustration)
Somatic NS ——————————-Ach
71
Parasympathetic Nervous System (illustration)
Parasymp NS ———————-Ach [ganglion] ————-Ach
72
Sympathetic Nervous System (illustration)
Symp NS —-Ach [Ganglia] —————————— NA — Ach [Ganglia] ——————————Ach —Ach [Ganglia] Adrenal Gland - - - - - -> ADR

Physiology Test 1 (2 decks)

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