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Physiology Module > Module 2 > Flashcards

Module 2 Flashcards

1
Q

Blocks release of Ach from presynaptic terminals

A

Botulinum toxin (botox)

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2
Q

a drug that blocks the gating action of Ach on the Ach channels by competing for ACh receptor sites on motor end plate

A

Curare

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3
Q

Inhibits acetylcholinesterase

A

Neostigmine

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4
Q

Blocks reuptake of choline into presynaptic terminal

A

Hemicholinium

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5
Q

Antibody directed against the ACh receptor

A

Myasthenia gravis

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6
Q

What is the effect of AChE inhibitor?

A

Blocks the degradation of ACh, causing an increase in the endplate potential, and prolongs the action of ACh at the motor endplate

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7
Q
  • A neuromuscular disease with classic symptoms of weakness and fatigue of skeletal muscles
  • Seen more commonly in females, with peak incidence at 20 to 30 years of age
  • Men have a peak of incidence at around 50 to 60 years of age
A

Myasthenia gravis

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8
Q

Classic symptoms of this disease is muscle weakness that increases with repetitive muscle use (eg, chewing) and partially recovers with rest

A

Myasthenia gravis

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9
Q
  • Most common muscular dystrophy
  • 1 in 3500 boys (3-5 yo)
  • Severe muscle wasting
    • Most patients are wheelchair bound by the age of 12
    • Respiratory failure in adulthood (30 to 40 years of age)
A

Duchenne’s muscular dystrophy

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10
Q

What is gower’s sign for Duchenne’s muscular dystrophy?

A

Using hands to push on legs to stand

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11
Q
  • X-linked recessive
  • Defect in the dystrophin gene –> deficiency of the dystrophin protein in skeletal muscle, brain, retina, and smooth muscle
A

Duchenne’s muscular dystrophy

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12
Q
  • A large (427 kDa) protein present in low abundance (0.025%) in skeletal muscle
  • Localized on the intracellular surface of the sarcolemma in association with several integral membrane glycoproteins (forming a dystrophin-glycoprotein complex)
A

Dystrophin

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13
Q
  • Tethers Myosin to Z lines (scaffolding)
  • Binds Z lines to M line
  • largest protein
A

Titin

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14
Q
  • Attaches to plasmalemma

- Stabilizes plasmalemma and prevents contraction-induced rupture

A

Dystrophin

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15
Q

Binds Actin to Z lines

A

Actinin and Capz Protein

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16
Q

Binds Z lines to plasma membrane

A

Desmin

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17
Q
  • Occurs when contracting muscles are stretched and lengthened too vigorously
  • More pain and stiffness than in not-so-vigorous muscle stretching and lengthening (cycling)
    Resultant dull, aching pain develops slowly and reaches peak in 24 to 48 hours
A

Delayed-onset Muscle Soreness

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18
Q
  • Pain associated with reduced range of motion, stiffness, and weakness of the affected muscles
  • Pain due to inflammation near myotendinous junctions
  • Slow recovery, depends on regeneration of the injured sarcomeres
A

Delayed-onset Muscle Soreness

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19
Q
  • A state of contracture several hours after death

- All the muscles of the body go contraction and become rigid even without action potentials

A

Rigor Mortis

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20
Q

Rigor Mortis results from loss of all the ATP. Why?

A

It is required to cause separation of the cross-bridges from the actin filaments during the relaxation process

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21
Q
  • Muscles remain in rigor until the proteins deteriorate (15 to 25 h later)
  • All these events occur more rapidly at higher temperatures
A

Rigor Mortis

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22
Q

exert opposite effects but operate reciprocally (complementary) or synergistically to produce coordinated responses

A

Dual Innervation

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23
Q

Single Innervation that has sympathetic only

A
  • sweat glands
  • adrenal glands
  • most blood vessels
  • pilomotor muscle
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24
Q

Single Innervation that has parasympathetic only

A
  • lacrimal muscle (tear glands)

- ciliary muscle (accommodation for near vision)

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25
Q

2 reasons why adrenal medulla is considered to be part of the ANS

A
  • Nerve supply to AM is anatomically and biochemically identical to autonomic preganglionic nerve fibers
  • Adrenomedullary cells are embryologically, anatomically and functionally identical to postganglionic autonomic nerve fibers
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26
Q

2 reasons why adrenal medulla is considered a component of SNS and not PSNS

A
  • Origin of nerve supply of AM is thoracolumbar
  • Adrenomedullary cells secrete catecholamines (Epinephrine – 80%; Norepinephrine – 20%, the neurotransmitter of sympathetic nerves)
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27
Q
  • mydriasis
  • increased ABP
  • vasoconstriction
  • increased in skeletal muscle strength
  • increased ventilation
A

Responses of the Sympathetic Nervous System

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28
Q
  • decreased GIT activity
  • elevation of plasma glucose and fatty acid levels
  • increase in mental activity
A

Responses of the Sympathetic Nervous System

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29
Q
  • lowers threshold in the reticular formation

- redistribution of blood from skin and splanchnic regions towards skeletal muscle

A

Responses of the Sympathetic Nervous System

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30
Q

location:
- radial muscle of iris
- blood vessels of skin, skeletal muscle, splanchnic region
- sphincters of GIT and bladder
mechanism of action:
- activate phospholipase C and increase the intracellular concentration of IP3

A

Alpha 1 Receptors

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31
Q

Antagonist of Alpha 1 receptors

A

Prazosin

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32
Q 
location:
- prominent in the heart
- salivary glands
- adipose tissue
- kidneys (promote renin secretion)
Mechanism of Action: 
- involves Gs protein activation of adenylcyclase to increase cAMP concentration
A

Beta 1 Receptors

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33
Q

sites:
- predominate in smooth muscle of airways
- blood vessels of skeletal muscles
- GIT and bladder walls
Mechanism of Action:
- same as beta 1
- involves Gs protein activation of adenylyl cyclase to increase cAMP concentration

A

Beta 2 Receptors

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34
Q

Potentiates cholinergic effects

A

Parasympathomimetic Agents

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35
Q

Parasympathomimetic Agents that interact with muscarinic receptors imitating ACh

A

Pilocarpine

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36
Q

Parasympathomimetic Agents that interacts with nicotinic receptors mimic ACh

A

Nicotine

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37
Q

Parasympathomimetic Agents that inactivate or inhibits acetylcholinesterase

A

Neostigmine

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38
Q

Blocks cholinergic effects

A

Parasympatholytic Agents

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39
Q

Parasympatholytic Agents that inhibit active uptake of choline from the blood to the axon terminal

A

Hemicholine

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40
Q

Parasympatholytic Agents that inhibits ACh release from synaptic vesicles

A

Botulinum Toxin

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41
Q

Parasympatholytic Agents that competes with ACh at muscarinic receptor sites

A

Atropine, Homatropine, Scopolamine

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42
Q

Potentiates adrenergic effect

A

Sympathomimetic Agents

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43
Q

Sympathomimetic Agents that interact with alpha-receptors

A

Methoxamine, Phenylephrine

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44
Q

Sympathomimetic Agents that interacts with beta-receptors

A

Salbutamol (Β2), Isoproterenol (Β1= Β2)

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45
Q

Sympathomimetic Agents that cause release of NE from its storage vesicles

A

Ephedrine, Amphetamine

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46
Q

Sympathomimetic Agents that prevents reuptake of NE by the postganglionic fibers

A

Cocaine

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47
Q

Blocks adrenergic effects

A

Sympatholytic Agents

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48
Q

Sympatholytic Agents that inhibit diffusion of NE out of the vesicle

A

Resirpine

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49
Q

Sympatholytic Agents that inhibits or blocks NE release from storage vesicles

A

Guanethedine

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50
Q

Sympatholytic Agents that blocks effects of NE on adrenoreceptors

A

Phenoxybenzamine, where is this used? pheochromocytoma

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51
Q

Sympatholytic Agents that competes with NE at beta receptors

A

Propranolol

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52
Q

Drug that does NOT block effects on alpha receptors. It blocks beta-receptors nonselectively

A

Propranolol

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53
Q

Function of Muscles

A
  • Movement

- Energy Storage

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54
Q

Types of Muscle

A
  1. Skeletal
  2. Cardiac
  3. Smooth
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55
Q
  • extremities, voluntary, striated multinucleated
    a. Intrafusal: Muscle Spindle
    b. Extrafusal: For Muscle Contraction
    i. White/Fast-Twitch Fiber
    ii. Red/Slow-Twitch Fiber
A

Skeletal Muscle

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56
Q

Contraction speed: Slow, prolonged
Myosin ATPase activity: Slow
Major ATP synthesis pathway: Aerobic/ Oxidative
SR Ca pumping capacity: Moderate (SERCA2)
Rate of fatigue: Slow

A

Type 1: Slow Oxidative (Red Muscle)

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57
Q 
Fiber diameter: small
Oxidative Capacity: High
Glycolytic capacity: Moderate
Activities: Endurance
Location: Soleus, anti-gravity muscles of the back
A

Type 1: Slow Oxidative (Red Muscle)

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58
Q 
Contraction speed: Fast
Myosin ATPase activity: Fast
Major ATP synthesis pathway: Glycolysis
SR Ca pumping capacity: High (SERCA1)
Rate of fatigue: Fast
A

Type IIB: Fast Glycolytic (White Muscle)

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59
Q 
Fiber diameter: Larger (2x)
Oxidative Capacity: Low
Glycolytic capacity: High (rapid release)
Activities: Quickness, Power
Location: EOM
A

Type IIB: Fast Glycolytic (White Muscle)

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60
Q 
- can be found in other animals
Contraction speed: Fast/ Intermediate
Myosin ATPase activity: Fast
Major ATP synthesis pathway: Aerobic/ Oxidative
SR Ca pumping capacity: High
Rate of fatigue: Intermediate
A

Type IIA: Fast Oxidative (Red to Pink)

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61
Q

Fiber diameter: Intermediate
Oxidative Capacity: Very High
Glycolytic capacity: High
Activities: Uncommon in humans

A

Type IIA: Fast Oxidative (Red to Pink)

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62
Q
  • found in heart; striated; single nucleus (centrally); involuntary
    a. Atrial Muscle Fibers
    b. Ventricular Muscle Fibers
    c. Conductive Muscle Fibers
A

Cardiac Muscle

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63
Q
  • found in colon, GIT, lungs; involuntary
    a. Multi-Unit Smooth Muscle
    b. Unitary Smooth Muscle
A

Smooth Muscle

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64
Q
  • One nerve, multiple muscle fibers that may act on their own
  • Controlled mainly by nerve signals (Ach, NE)
  • (-) Gap junctions
  • No True Action Potentials (Electrotonic Conduction)
  • (-) Spontaneous contractions
  • e.g. Ciliary Eye Muscle, Iris, Piloerector muscle, Vas Deferens
A

Multi-Unit Smooth Muscle

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65
Q
  • One nerve, multiple muscle fibers that are act together as one
  • Maybe controlled by nerve (Ach, NE), hormones, stretch, local factors
  • (+) Gap junctions
  • Slow/Pacemaker waves, Spike Potentials and Plateau Potentials
  • May exhibit spontaneous contractions
  • e.g. Intestines, Bile Ducts, Ureters, Uterus
A

Unitary Smooth Muscle (aka Syncitial Smooth Muscle, Visceral Smooth Muscle)

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66
Q
  • Rhythmic, Intermittent

E.g. walls of the GI and urogenital tracts

A

Phasic Smooth Muscle

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67
Q
  • Continuously active

E.g. Vascular smooth muscle, respiratory smooth muscles, sphincters

A

Tonic Smooth Muscle

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68
Q

Composition of Skeletal Muscle

A

Sarcomeres -> Myofibril -> Muscle Fiber -> Muscle Fascicle -> Skeletal Muscle

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69
Q

Surrounds Muscle Fiber

A

Endomysium

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70
Q

Surrounds Muscle Fascicle

A

Perimysium

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71
Q

Surrounds Skeletal Muscle

A

Epimysium

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72
Q

Plasma membrane surround muscle fiber

A

Sarcolemma

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73
Q

invaginations of the sarcolemma in close proximity to the terminal cisternae of the Sarcoplasmic Reticulum

A

Transverse Tubules

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74
Q
  • Endoplasmic reticulum surrounding myofibril

- Contains Calcium

A

Sarcoplasmic Reticulum

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75
Q
  • Functional unit of the muscle
  • Area between two Z lines
  • Exhibited by certain muscle types only
  • Has thick filaments and thin filaments
A

Sarcomere

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76
Q

Myosin

  • Two Heavy Chains: MYOSIN TAIL
  • Free Ends of Heavy Chains + Light Chains: MYOSIN HEAD
  • Tails bundled together: BODY
  • Arms and Myosin Heads: CROSS-BRIDGES
  • Arm-Body and Arm-Head: HINGES
A

Thick Filaments

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77
Q

o Actin
o Tropomyosin
o Troponin

A

Thin Filaments

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78
Q

attaches troponin complex to tropomyosin

A

Troponin T

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79
Q

inhibits actin-myosin binding

A

Troponin I

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80
Q

calcium binding protein

A

Troponin C

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81
Q
  • contain myosin and actin

- contain the entire length of the thick filament

A

A Band

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82
Q
  • contain the remaining thin filament
A

I Band

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83
Q
  • Tethers Myosin to Z lines (scaffolding)

- Binds Z lines to M line

A

Titin

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84
Q
  • Attaches to plasmalemma

- Stabilizes plasmalemma and prevents contraction-induced rupture

A

Dystrophin

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85
Q

Binds Actin to Z lines

A

Actinin and Capz Protein

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86
Q

Binds Z lines to plasma membrane

A

Desmin

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87
Q
  • Involves motor neurons and extrafusal fibers

- Demonstrated by the Sliding Filament Model

A

Skeletal Muscle Contraction

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88
Q
  • Thin filaments “slides” against the thick filaments towards the center of the sarcomere
  • Z-discs meets the myosin filaments
A

Sliding Filament Model

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89
Q

if activated, this receptor would activate RYANODINE RECEPTOR (a calcium release channel)

A

Dihydropyridine Receptor

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90
Q

it would sequester the Calcium back once the action potential is gone

A

Calsequestrin

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91
Q

Force to cause the contraction

A

Power Stroke

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92
Q

Mutation in dystrophin in the heart

A

Dilated Cardiomyopathy

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93
Q

What is the distance achieved in each cross-bridge cycle?

A

10 nanometer

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94
Q
  • Brief muscular contraction followed by relaxation
  • due to a single action potential
  • Starts 2 millisecond after depolarization of the membrane
  • Duration: 7.5 ms in “Fast” Fibers; 100 ms in “Slow” Fibers
A

Muscle Twitch

95
Q
  • All muscle fibers innervated by a single motor nerve fiber
    o Made up of alpha motor neuron, its axon and all muscle fibers it supplies
    o Alpha motor neurons are also called “final common pathway”, “lower motor neuron”
  • For movements that require rapid and exact control
    o One motor nerve fiber would innervate few muscles
A

The Motor unit

96
Q

Large amount of ATP are cleaved to form ADP during contraction process, and the greater the amount of work performed by the muscle, the greater the amount of ATP that is cleaved; this phenomenon is called _____

A

The Fenn Effect

97
Q

Muscle contraction is said to be ___ when the muscle does not shorten during contraction

A

Isometric

98
Q

Muscle contraction is said to be ___ when the muscle does shorten but the tension on the muscle remains constant throughout the contraction

A

Isotonic

99
Q
  • means adding together of individual twitch contractions to increase intensity of overall muscle contraction
A

Summation

100
Q
  • Type of summation that occurs by increasing the number of motor units contracting simultaneously
  • size principle is followed
  • Motor units driven asynchronously by the spinal cord
  • Contraction alternates among motor units one after the other
A

Multiple Fiber Summation (Spatial Summation)

101
Q

Type of summation that occurs by increasing the frequency of contraction and sometimes can lead to TETANIZATION

A

Frequency Summation (Temporal Summation)

102
Q
  • Smaller motor units are recruited first before big motor units
  • Basis: small motoneurons in the spinal cord are more excitable than large ones
A

Size Principle

103
Q

When the frequency reaches a critical level, the successive contractions eventually become so rapid that they fuse together and the whole muscle contraction appears completely sooth and continuous. This process is called ___

A

Tetanization

104
Q
  • Each contraction occurs after complete relaxation, its initial strength of contraction may be as little as one half its strength
  • Each contraction increases up to plateau
  • Due to Ca++ accumulation, increase in temperature, ph changes
  • Seen in warm-up exercise
A

Staircase Effect or Treppe

105
Q
  • Complete relaxation not given; subsequent stimuli done

Results in progressive increase in total contraction strength

A

Wave Summation

106
Q
  • no relaxation after contraction
A

Complete Tetany

107
Q

incomplete relaxation after contraction

A

Incomplete Tetany

108
Q

Which of the following tetanizes at lower stimulus frequency?

A

Slow-Twitch Fibers

109
Q

Which of the following has a larger maximal force during tetany?

A

Fast-Twitch Fibers

110
Q

Tension developed by stretching the muscle to different lengths

A

Passive Tension

111
Q

The tension developed when the muscle is stimulated to contract at different lengths.

A

Active Tension

112
Q

Active Tension + Passive Tension

A

Total Tension

113
Q

If the resting muscle length is extended, the following will happen:

A

Passive Tension: Increases
Active Tension: Decreases
Force of Contraction: Increases

114
Q
  • With zero load, shortening velocity is maximal
    Corresponds to the maximal cycling rate of the cross-bridge
  • Increasing the load, decreases the velocity of the muscle shortening
A

Force-Velocity Relationship

115
Q
  • Reflects work done at each load
  • Maximal rate of work done at a submaximal load (when force of contraction is approximately 30% of the maximal tetanic tension)
A

Power-Stress Curve

116
Q
  • Length is held constant
  • No muscle shortening/lengthening
    E.g. holding an Ipad in midair
A

Isometric Contraction

117
Q
  • Load is held constant
  • With Muscle Shortening: CONCENTRIC CONTRACTION (e.g.pulling a weight up)
  • with muscle lengthening: ECCENTRIC CONTRACTION (e.g. lowering a weight down)
A

Isotonic Contraction

118
Q
  • Remaining contractile activity of the muscle at rest
  • Due to low levels of contractile activity in some motor units driven by reflex arcs from muscle spindles
  • Helps maintain posture
A

Muscle Tone

119
Q
  • Protective mechanism to prevent muscle cell injury or death
  • Directly proportional to rate of depletion of muscle glycogen and creatine phosphate stores and the accumulation of lactic acid
  • Occurs earlier in fast-twitch fibers
A

Muscle Fatigue

120
Q
  • increase of the total mass of a muscle

- Maybe due to be due to fiber hypertrophy or sarcomere addition

A

Muscle Hypertrophy

121
Q
  • total mass is decrease
  • Seen in denervation
  • when a muscle remains unused for many weeks, the rate of degradation of contractile proteins is more rapid than the rate of replacement
A

Muscle Atrophy

122
Q
  • increase in the number of actin and myosin filaments in each muscle fiber, causing enlargement of the individual muscle fibers
A

Fiber Hypertrophy

123
Q
  • actual number of muscle fiber has been observed to increase in addition to the fiber hypertrophy
A

Fiber Hyperplasia

124
Q

The fibrous tissue that replaces the muscle fibers during denervation atrophy also has a tendency to continue shortening for many months, which is called ___

A

Contracture

125
Q

o Will have Muscle Fasciculation
- Small, irregular contractions (due to Ach release from degenerating axons)
o Will have Muscle Fibrillation
- Spontaneous, repetitive contractions (Cholinergic receptors spread out over entire cell membrane)
o Function may fully return w/in 3 months due to Reinnervation
o No further return of function after 1-2 years
o Replaced by fibrous-fatty tissue

A

Muscle Denervation

126
Q

Remaining nerve fibers sprout new axons (innervate many paralyzed muscle fibers) -> macromotor units -> muscles become stronger but w/less control

A

Poliomyelitis

127
Q
  • several hours after death, all the muscles of the body will go into a state of contracture
  • the rigidity results from loss of all ATP (required to cause separation of cross-bridges from the actin filaments during the relaxation process)
  • Start after 3-6 hours
  • End after 15-25 hours; earlier in high temp
A

Rigor Mortis

128
Q

Anti-Ach receptor antibodies

A

Myasthenia Gravis

129
Q
  • milder form of dystrophy

- is also caused by mutations of the gene that encodes for dystrophin but has later onset and longer survival

A

Becker Muscular Dystrophy

130
Q

Skeletal muscle fibers are innervated by large, myelinated nerve fibers that originate from large motoneurons in the ____

A

Anterior horns of the Spinal Cord

131
Q

A junction between a single axon terminal and the muscle fiber membrane. The invaginated membrane is called the ____

A

Synaptic gutter or synaptic through

132
Q

A space between the terminal and the fiber membrane is called the ___

A

Synaptic space or synaptic cleft

133
Q

at the bottom of the gutter are numerous smaller folds of the muscle membrane called ____

A

Subneural clefts

134
Q
  • neurotransmitter that excites muscle fiber membrane

- synthesize in the cytoplasm terminal, but is absorbed rapidly into many small synaptic vesicles

A

Acetylcholine

135
Q
  • found in the synaptic space

- enzyme which destroys acetylcholine a few milliseconds after it has been released from the synaptic vesicles

A

Acetylcholinesterase

136
Q
  • initiates an action potential that spreads along the muscle membrane and thus creating muscle contraction
A

End plate potential

137
Q

drugs that stimulate the muscle fiber by Ach like action

A

Metacholine, Carbachol, Nicotine

138
Q

drugs that stimulate the neuromuscular auction by inactivating acetylcholinesterase

A

Neostigmine, Physostigmine, Diisipropyl flurophosphate

139
Q
  • smooth muscle cells contain a large amount of another regulatory protein called ___
  • this protein initiates contraction by activating the myosin cross-bridges
A

Calmodulin

140
Q

Special mechanism in the heart cause a continuing succession of heart contraction

A

Cardiac rhythmicity

141
Q
  • dark areas crossing the cardiac muscle fibers

- cell membranes that separate individual cardiac muscle cells from one another

A

Intercalated discs

142
Q
  • Exhibits atrial and ventricular Syncitium (contract together)
  • Uses EXTRAcellular and INTRAcellular Calcium
  • Atrial and Ventricular AP is different form Conductive
    System AP (SA Node)
A

Cardiac Muscle Contraction

143
Q
  • More developed T-tubule, Less Developed SR compared
    to skeletal Muscles
  • Calcium Regulation of Cardiac muscles
    1. Calcium Channels (increases intracellular
    calcium)
    a. L-Type or Slow Calcium Channel ->predominant; voltage-gated
    b. Fast calcium channel
    2. 3Na+-1Ca++ Exchanger (decreases
    intracellular calcium)
    3. Ca-ATPase pump (decreases intracellular
    calcium)
A

Cardiac Muscle Contraction

144
Q

Cardiac Muscle vs Skeletal Muscle

A

Cardiac Muscles: Electrochemical Coupling (Ca++-
induced release of Ca++)

Skeletal Muscles: Eletromechanical Coupling
(interaction between DHPR and RYR)

145
Q

Cardiac Muscle vs Skeletal Muscle

A

Cardiac Muscles: T-tubules in the Z lines
Skeletal Muscles: T-tubules at the ends of I-bands

Cardiac Muscles: Syncitium, No Tetany (Due to long refractory period secondary to voltage-gated L-type Calcium Channels)
Skeletal Muscles: Recruitment, may undergo tetany

146
Q
  • No troponin
  • Contains the following: MLCK (Myosin Light Chain Kinase); Calmodulin; Caldesmon, Calponin
  • MYOSIN-based regulation
  • Contains DENSE BODIES (Similar to z discs)
    SARCOPLASMIC RETICULUM (SR) - rudementary (smooth muscle rely on extracellular Calcium
A

Smooth Muscle Contraction

147
Q
  • Rudimentary t-tubules
  • Contains Voltage-gated L-type Ca++
    Channel And The 3Na+-1Ca++
    Antiporter
A

Caveoli

148
Q
  • Desmin and Vimentin

- Connect dense bodies with cytoskeletal network

A

Intermediate Filament

149
Q
  • Opens slowly and remains open much longer

- Used by hormones, NT

A

InsP3-gated Ca++ channel

150
Q
  • Causes relaxation vascular smooth muscles

- Used by Nitric Oxide, Adenosine, drugs, hormones

A

cAMP & cGMP mechanisms

151
Q

Sponteneous elevation in intracellular calcium levels

A

Ca++ “sparks”

152
Q
  • Uses much less ATP
  • Slow onset but prolonged time for contraction
    “Latch” State: force of contraction maintained with low
    energy expenditure (300x less than skeletal muscles) during tonic contraction
  • Greater force of contraction (4-6 kg/cm2)
  • May produce connective tissue (e.g. atherosclerosis)
A

Smooth Muscle

153
Q

Cardiac Muscle Action Potential

A

Phase 0: Rapid Depolarization - Sodium Influx
Phase 1: Initial Repolarization - Partial efflux of K
Phase 2: Plateau - influx of Ca+2
Phase 3: Final repolarization - Complete potassium influx
Phase 4: Resting - slightly more than influx of K

154
Q

Which are the one that increases Calcium?

A
  1. L Type
  2. Calcium ATPase
  3. Calcium Sodium Antiport
155
Q

♣ output from the CNS travels along two pathways that are anatomically and functionally distinct

A

Nervous System

156
Q

α-motor neuron links CNS to skeletal muscles

A

Somatic Motor Neurons (SNS)

157
Q

autonomic neurons links CNS to visceral organs

A

Autonomic Motor Neurons (ANS)

158
Q

ANS and SNS are organized on the basis of the reflex arc, composed of:

A

afferent limb
integrating center
efferent limb

159
Q

afferent fibers from visceral structures reach CNS via ___

A

autonomic pathways

160
Q

visceral afferents are found in the:

A

CN 7, 8, 9 and 10 (VAGUS nerve is the most parasympathetic

161
Q

Pathway: SINGLE NEURON PATHWAY
Neurons involved: ALPHA-MOTOR NEURONS (large diameter, myelinated, rapidly conducting
Effector: SKELETAL MUSCLE
Innervation of effector: skeletal muscle innervated by single neuron
Neurotransmitter: Ach only

A

Somatic Nervous Sytem

162
Q

Effect of NT: release of Ach (contraction of skeletal muscle)
Location: NEUROMUSCULAR JUNCTION
Location of NT synthesis and storage: AXON TERMINAL
Postsynaptic receptors: NICOTINIC RECEPTOR (N1) at Motor End Plate (MEP)

A

Somatic Nervous System

163
Q

Pathway: TWO WAY NEURON PATHWAY
Neurons involved: PREGANGLIONIC - small diameter, myelinated, slow conducting B fibers
POSTGANGLIONIC - small diameter, unmyelinated C fibers
Effector: VISCERAL stuctures
Innervation of effector: VISCERAL effectoe may be innervated by many postganglionic neurons
Neurotransmitter: Ach, NE, Epi, Dopamine

A

Autonomic Nervous System

164
Q

Effect of NT: response may be INHIBITORY of EXCITATORY
Location: NEUROEFFECTOR JUNCTION
Location of NT synthesis and storage: BEADS or VARICOSITIES that line the branching networks of postganglionic neurons
Postsynaptic receptors: postsynaptic receptors widely distributed on the target tissues
no specialized region of receptors like the MEP

A

Autonomic Nervous System

165
Q
  • part of the nervous system responsible for homeostasis
  • regulatory in function
  • essentially motor
  • without ANS, survival is possible but the ability to adapt to stressors from the environment will be severely compromised
  • striking characteristics - rapidity and intensity with which it can change visceral functions
A

Autonomic Nervous System

166
Q
  • can increase HR to 2x normal within 3-5 secs.
  • can double ABP in 10-15 secs.
  • can cause sweating within secs. operates through visceral reflexes
A

Autonomic Nervous System

167
Q

Most of the organs are parasympathetically innervated except for _____

A

Sweat glands, blood vessel

168
Q

Classification of the ANS

A

Anatomic differences
Functional differences
Biochemical differences
Pharmacologic differences

169
Q

Divisions of ANS Based on Anatomic Differences

A
  • Sympathetic NS
  • Parasympathetic NS
  • Enteric Nervous System / Intramural Nerve Plexus of GIT
170
Q
  • “mini brain” because it contains all elements of nervous system
  • sensory and motor neurons, and interneurons (plexuses)
  • can function autonomously but normal GI function often requires communication between the CNS and the ENS
  • confined within GIT walls
  • two divisions:
    Myenteric or Auerbach’s Plexus - contraction of smooth muscle
    Meissner’s or Submucosal Plexus - secretion
A

Enteric Nervous System

171
Q
  • Thoracolumbar Outflow
  • larger division
  • prepares individual to cope with emergency
  • ensures that the body can respond appropriately to a stressful or emergency situation
  • concerned with mobilizing the person for “fight or flight”
A

Symphathetic Nervous Sytem

172
Q 
♣ mydriasis
♣ increased ABP
♣ vasoconstriction
♣ increased in skeletal muscle strength
♣ increased ventilation
A

Symphathetic Nervous Sytem

173
Q

♣ decreased GIT activity
♣ elevation of plasma glucose and fatty acid levels
♣ increase in mental activity
♣ lowers threshold in the reticular formation
♣ redistribution of blood from skin and splanchnic regions towards skeletal muscle

A

Symphathetic Nervous Sytem

174
Q

a neuroendocrine organ

A

Adrenal Medulla

175
Q

2 reasons why adrenal medulla is considered to be part of the ANS

A
  1. Nerve supply to AM is anatomically and biochemically identical to autonomic preganglionic nerve fibers
  2. Adrenomedullary cells are embryologically, anatomically and functionally identical to postganglionic autonomic nerve fibers
176
Q

2 reasons why adrenal medulla is considered a component of SNS and not PSNS

A
  1. Origin of nerve supply of AM is thoracolumbar
  2. Adrenomedullary cells secrete catecholamines
    Epinephrine – 80%
    Norepinephrine – 20%, the neurotransmitter of sympathetic nerves
177
Q
  • Craniosacral Outflow
  • dominates in quiet, relaxed situation
  • activity tends to conserve energy and restore the body’s resources (anabolic nervous system)
A

Parasympathetic Nervous System

178
Q
  • cranial outflow supplies the visceral structures in the head through CN 3, 7 and 9 and the structures in the thorax and upper abdomen through CN 10
  • sacral outflow supplies pelvic viscera through pelvic branches of the 2nd to 4th spinal nerves
A

Parasympathetic Nervous System

179
Q

Origin of preganglionic neuron: CRANIOSACRAL
Location of peripheral ganglia: TARGET ORGAN
Length of preganglionic fiber: LONG
Length of postganglionic fiber: SHORT
Degree of branching of preganglionic nerve: LESS BRANCHING

A

Parasympathetic Nervous System

180
Q

Origin of preganglionic neuron: THORACOLUMBAR
Location of peripheral ganglia: PARAVERTEBRAL
Length of preganglionic fiber: SHORT
Length of postganglionic fiber: LONG
Degree of branching of preganglionic nerve: MORE BRANCHING

A

Sympathetic Nervous System

181
Q

Nature of activity: Dominates in emergency (“fight or flight”) situations
Energy utilization: Involves expenditure of energy (catabolic)
Response: appropriate to emergency and stress situations; synchronized and coordinated
Range of Effect: Affects widespread regions of the body (“mass discharge”)

A

Sympathetic Nervous System

182
Q

Fiber Connections: Due to divergent connection (1:20)
Branching of preganglionic fibers: Preganglionic fibers branch extensively
Neurotransmitters: Catecholamines secreted by adrenal medulla are distributed to all regions of the body through circulation
Duration of Response: Sustained duration due to slow deactivation of norepinephrine (active reuptake)
- Norepinephrine lingers in the synaptic cleft for a longer time than acetylcholine
- Effects triggered by adrenergic neurons are longer lasting

A

Sympathetic Nervous System

183
Q

Nature of activity: Dominates in quiet, relaxed situations
Energy utilization: Tends to conserve energy (anabolic) and restores the body’s resources
Response: favors digestion and absorption of food ( activity of intestinal muslces, intestinal secretion)
Range of Effect: Discrete, selective and limited
Localized to a single organ

A

Parasympathetic Nervous System

184
Q

Fiber Connections: Manner of fiber connection is 1:1 or 1:2
Branching of preganglionic fibers: Limited branching of preganglionic fibers
Neurotransmitters: Usually no acetylcholine in circulation
Duration of Response: Short duration due to fast deactivation of acetylcholine (enzyme hydrolysis by acetylcholinesterase)

A

Parasympathetic Nervous System

185
Q
  • Exert opposite effects but operate reciprocally to produce coordinated responses
  • The 2 divisions can also act in a synergistic or cooperative manner
A

Dual Innervation

186
Q

SYMPATHETIC only

A

sweat glands
adrenal glands
most blood vessels
pilomotor muscle

187
Q

PARASYMPATHETIC only

A 
lacrimal muscle (tear glands)
ciliary muscle (accommodation for near vision)
188
Q

Parasympathetic transmitter

A

Acetylcholine

189
Q

Synpathetic transmitter

A

Norepinephrine

190
Q

2 tissue enzyme that can cause destruction of norepinephrine

A
  • Monoamine oxidase (found in the nerve endings)

- Catechol-O-methyl transferase (present diffusely in the tissues)

191
Q

Binding of norepinephrine with its receptor increases the activity of the enzyme adenylyl cyclase which causes formation of ___

A

Cyclic adenosine monophosphate (cAMP)

192
Q

Acetylcholine activates two types of receptors which are called

A

Muscarinic

Nicotinic receptors

193
Q
  • A receptor which uses G protein as their signaling mechanism
  • found on all effector cells that are stimulated by the postganglionic cholinergic neurons
A

Muscarinic receptors

194
Q
  • are ligand-gated ion channels found in autonomic ganglia at the synapses between the preganglionic and postganglionic neurons of both PNS and SNS
  • are also present at many nonautonomic nerve endings
A

Nicotinic receptors

195
Q

Alpha receptor and function

A 
Vasoconstriction
Iris dilation
Intestinal relaxation
Intestinal sphincter contraction
Pilomotorcontraction
Bladder sphincter contraction
Inhibits neurotransmitter release (alpha1)
196
Q

Beta receptor and fuction

A 
Vasodilation (b2)
Cardioacceleration (B1)
Increased myocardial strength (B1)
Intestinal and uterus relaxation (B2)
Bronchodilation (B2)
Calorigenesis (B2)
Glycogenolysis, bladder wall relaxation (B2)
Lipolysis (B1)
Thermogenesis (B3)
197
Q

A synthetic hormone chemically similar to epinephine and norepinephrine that has extremely strong action on B receptors but no action on A receptors

A

Isopropyl norepinephrine

198
Q

Parasympathetic exitation contracts ___ which releases the tension on the ligaments and allow the lens to become more convex causing eye to focus near at hand.

A

Ciliary muscle

199
Q

The nasal, lacrimal, salivary and many gastrointestinal glads ares strongly stimulated by ___, usually resulting in copious quantities of watery secretions.

A

Parasympathetic nervous system

200
Q

Gland of the small and large intestines are controlled principally by local factors in the intestinal tract itself and by ___

A

Intestinal enteric nervous system

201
Q

Synthesis and Storage: Acetylcholine (Parasympathetic)

A

Acetyl Coa + Choline -> Acetylcholine (choline acetyltransferase)

  • synthesized in the cytoplasm of axon terminal by acetylation
  • stored as clear round vesicles
    choline comes from the ECF and enters the axon terminal by active transport
  • acetyl-CoA and ATP provided by mitochondria
  • choline acetyltransferase synthesized in the soma and brought to axon by axoplasmic transport
202
Q

Synthesis and Storage: Norepinephrine (Sympathetic)

A
  • synthesized from the amino acids phenylalanine and tyrosine
    Phenylalanine -> Tyrosine (phenylalanine hydroxylase)
    Tyrosine -> DOPA or dyhydroxy phenylalanine (tyrosine hydroxylase)
    DOPA -> Dopamine (DOPA decarboxylase)
203
Q

In the adrenal medulla, ____ catalyzes the conversion of norepinephrine to epinephrine.

A

phenylethanolamine-N-methyltransferase (PEMT)

204
Q

undergoes enzymatic destruction via acetylcholinesterase diffusion

A

Acetylcholine

205
Q

undergoes active reuptake by the prejunctional junctional fiber diffusion into the extracellular spaces

A

Norepinephrine

206
Q

enzymatic destruction of NE (Norepinephrine) while it is still in the synaptic cleft

A

catechol-ortho-methyltransferase (COMT)

207
Q

enzymatic destruction of NE while it is still in the axoplasm of the preganglionic fiber

A

monoamine oxidase (MAO)

208
Q

Location: cell bodies of postganglionic neurons
effector organs

Mechanism of Action
when a NT binds with receptor → causes a conformational change in the structure of the protein molecule → the cell may either be activated or inhibited

A

Autonomic Receptors

209
Q

How do NTs work?

A

by causing a change in membrane permeability to various ions

210
Q
  • have affinity for nicotine (small amounts)
  • excess nicotine acts as a blocking agent by persistent depolarization
  • sites: MEP, all autonomic ganglia, chromaffin cells of AM
  • types: N1 and N2
A

Nicotinic Receptor

211
Q

Differences between Nicotonic receptors in MEP and autonomic ganglia

A
  • both activated by the agonist Ach, nicotine, and carbachol
  • both antagonized by curare
  • hexamethonium, an antagonist, blocks N2 receptors but not N1
  • hexamethonium produces vasodilation can be used for the treatment of hypertension
212
Q
  • have affinity for muscarine (a mushroom poison when introduced into the body can mimic ACh on particular sites)
    sites: effector cells activated by PS; effector cells activated by S cholinergic
A

Muscarinic Receptors

213
Q

Types of Muscarinic Receptors

A

M1 - enhances gastric acid secretion
M2 - most abundant in the heart, smooth muscle in intestine, uterus, trachea, bladder
Mechanism of action: binding of agonist to M2–> inhibits adenylcyclase
M3 - smooth muscle of airways
Mech of action: formation of IP3 (inositol 1, 4, 5 triphosphate) and DAG(Diaglycerol) and increase in intracellular calcium
M4 - pancreatic acinar cells and islet tissue
M5 - sphincter muscle of iris, esophagus, parotid gland, cerebral blood vessel

214
Q

are of the indirect ligand G protein linked type

A

Adrenoceptors

215
Q

Types of Adrenoceptors

A 
Alpha 1 Receptors
Alpha 2 Receptors
Beta 1 Receptors
Beta 2 Receptors
Beta 3 Receptors
216
Q
  • location: radial muscle of iris; blood vessels of skin (vasoconstriction); sphincters of GIT and bladder
  • antagonist: Prazosin
  • mechanism of action: - involves a G protein (Gq) activate phospholipase C and increase the intracellular concentration of IP3
A

Alpha 1 Receptors

217
Q

location: presynaptically (autoreceptors) inhibit release of NE ; GIT walls
selective antagonist: Yohimbine
Mechanism of Action: - involves Gi protein act through inhibition of adenylyl cyclase → decreased cAMP levels
Example:
activation of alpha 2 receptors in GIT wall → relaxation

A

Alpha 2 Receptors

218
Q

location: prominent in the heart, salivary glands, adipose tissue, kidneys (promote renin secretion)
Mechanism of Action: involves Gs protein activation of adenylcyclase to increase cAMP concentration

A

Beta 1 Receptors

219
Q

sites: predominate in smooth muscle of airways, blood vessels of skeletal muscles (vasodilation), GIT and bladder walls
Mechanism of Action: same as beta 1
- involves Gs protein activation of adenylyl cyclase to increase cAMP concentration

A

Beta 2 Receptors

220
Q
  • present on cells of brown adipose tissue

- activation causes thermogenesis (heat production)

A

Beta 3 Receptors

221
Q

a drug that binds to the receptors for a neurotransmitter and that promotes the processes that are stimulated by that NT is said to be an agonist of that NT

A

Agonist

222
Q

a drug that blocks the action of a NT

A

Antagonist

223
Q
  • autonomic and somatic reactions work together to maintain essential body states and to effect necessary adaptation
  • levels of autonomic integration within the CNS are arranged in a hierarchy
  • CNS controls the activity of the ANS shows hierarchy in the control mechanism
A

Central Control of Autonomic Functions

224
Q
  • simple reflexes like contraction of a full bladder are integrated in the spinal cord

transection of the spinal cord&raquo_space; spinal shock&raquo_space; absence of reflexes, low ABP

A

Spinal Cord

225
Q
  • center for the regulation of the ANS
  • called by Sherrington, “the HEAD GANGLION,” of the ANS because stimulation of this produces autonomic responses
    sympathetic: posterior center
    parasympathetic: anterior center
  • integrates somatic, autonomic and endocrine functions
  • mediates those reactions that maintain homeostasis
A

Hypothalamus

226
Q
  • unit that regulates emotional and instinctual behavior

- concerned with the following: regulation of feeding behavior; expression of rage and fear; control of sexual behavior

A

Limbic System

227
Q
  • refinement of control over the autonomic and somatic reactions
  • examples: tells whether emotion is pleasant or unpleasant; responsible for voluntary control of respiration
A

Cerebral Cortex

228
Q
  • Where centers for regulation of cardiovascular and respiratory centers are located
  • The medullary areas for the autonomic control of the CVS and respiratory system are called the vital areas because damage to them is fatal
  • Deglutition, coughing, sneezing, gag reflex, vomiting reflexes are integrated in the medulla
  • EXAMPLES: respiratory center, vasomotor center, swallowing center, vomiting
A

Medulla Oblongata

229
Q

those that control pupillary responses to light are integrated in the ____

A

Midbrain

230
Q

Muscarinic receptor in brain (presynaptic neuron) and enhances gastric acid secretion

A

M1

231
Q
  • most abundant in the heart
  • smooth muscle in intestine, uterus, trachea, bladder
  • mechanism of action: binding of agonist»inhibits adenylcyclase
A

M2

232
Q
  • smooth muscle airways
  • mechanism of action: formation of IP3 (inositol 1,4,5 triphosphate) and DAG (diaglycerol) and increase in intracellular calcium
A

M3

233
Q

-muscarinic receptors found in pancreatic acinar cells and islet tissue

A

M4

234
Q

Muscarimic receptor for sphincter muscle of iris, esophagus, parotid gland, cerebral blood vessel

A

M5

Physiology Module (8 decks)

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