Ch 10 Muscle Phsiology Flashcards Preview

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Flashcards in Ch 10 Muscle Phsiology Deck (111):
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Terminal cisternae

Infoldings of SR run perpendicular to the myofibrils

1

Triad

Terminal cisternae(2) + T Tubule

2

Triad works as

A voltage sensor for the muscle fiber

3

Sarcomere

Functional unit, approx. 10,000 sarcomeres in one myofibril,

4

Myofilaments

Thick and thin

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Thin filaments

Composed of actin protein, toward ends of the sarcomere

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Thick filaments

Composed of myosin protein, toward the middle of the sarcoma

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M line

Middle, where thick filaments interconnect

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Z line

Zig zag proteins actinin at ends of sarcomere

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A band

Dark in appearance, thick filaments, includes zone of overlap

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J band

Light in appearance, where thin filaments are- include Z line

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H zone

No overlap between thin and thick

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Thin filaments

•composed of twisted actin protein
• active sites along chain
•A rest, tropomyosin covers the active site to prevent binding
• tropinin- sits atop tropomyosin to ensure active site covering

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Thick filaments

Composed of myosin proteins
Consists of a head and tail
The heads point away from M line
Forming a crossbridge

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1st step in a muscle contraction

Ca+2 ion released by terminal cisternae

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2nd step of a muscle contraction

Ca2+ attached to tropinin

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3rd step of muscle contraction

Tropinin-tropomyosin complex swings away from the actin is exposed

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5th step

Myosin heads attach to active site cross bridge forms

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6th step

Myosin pivots, pulling the actin toward the M line

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7th step

Myosin detaches and thin slides back into place

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Summary of muscle contraction

Attach
Cross-bridge
Pivot
Detach
Return

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Rigor Mortis

Rigidity of death

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What is rigor Mortis

After seat, cell membranes become leaky, so Ca2+ leaks of SR. Myosin heads attah to actin, but no ATP is being made, so can't detach

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When does rigor Mortis begin

3/4 hours after death and muscles remain stuff for 15-24 hours

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What happens 24 hours later?

Lysozyme will destroy all cross-bridge

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NMJ=

Neuromuscular junction

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Where is NMJ located

Connection between a motor neuron and muscle fiber exists

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Synaptic cleft

Small gap between the cells

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Acetylcholine

Communication between the cells occurs through a chemical neurotransmitter

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Where is ACH stored?

Neuron in synaptic vesicles

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Motorend plate

Has ACH receptors

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1st step that occurs at NMJ

Action potential arrives at end of motor neuron

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2nd step at NMJ

ACH released from synaptic vehicle by exocytosis

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3rd steps that occurs at NMJ

ACH wanders through synaptic cleft

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Step of 5 of NMJ

Influx of NA+ ions from extra cellular fluid across the servile a

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Step 6 NMJ

Muscle a.p. Generated along t tubule

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Step 7 of NMJ

Ca2+ ions released from t cisternae as a.p. Passes

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Step 8 of NMJ

Contraction begins, A chase breaks down ACH bound to motor end plate receptors

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step 9 NMJ A

ACH receptors occurs at motor neuron

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Black widow venom

Blocks a.p. From neuron

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Tetanus

40%-60% mortality rate "lock jaw"

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Botulinus toxin

Blocks exocytosis of ACH, Botox injections

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Myasthenia gravis

Loss of ACH receptors at m.e.p. Genetic tendency with autoimmune response

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Curare

Plant toxin poison darts used by South American tribes, binds to ACH receptors, blocking the real ACH FROM BINDING

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Tension

The amount of force exerted by the myosin head

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Minimal tension

Initial stimulation causes only the myosin heads in the zone of overlap to attach

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Twitch

One contraction once relaxation

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Latent phase

A.p. Process sarcolemma, ca2+ ions released

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Contraction phase

Ca2+ binds active sites exposed myosin heads bind

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Recovery phase

Ca2+ re absorbed active sites covered

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Twitch

Single contraction

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Summation of twitches

Repeated stimulation. After contraction.

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Incomplete tetanus

Rapid stimulation with partial relaxation can occur

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Tone

Number of myosin heads that are blind to actin at a given time

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Active muscles use..

600 trillion ATP molecules

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Where does ATP come from?

ATP styles in muscle
Creatine phosphate
Glycogen

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Aerobic respiration

Remember Kreb's or Citric acid cycle

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Anaerobic

Fermentation yields 2 ATP

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When muscle becomes active, co reduced back to ATP

Creative phosphokinase

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Lack of energy

Seen in long distance runners. Use ATP at slow rate, below normal rate of ATP generation, so they get endurance. Muscles fatigue when they run out of glycogen reserves. pH lowers

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Build-iPod lactic acid

Seen in sprinters. Acid build up during recovery period from contraction. PH lowers

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Intermediate muscle fiber

Most skeletal muscles are a combo of fast and slow fibers
Can morph to fast or slow with training

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Duchenne muscular dystrophy

Sex-linked genetic disease
Muscle cells lacking dystrophin protein
Dystrophin anchors thin filaments to sarcolemma, and regulates channels in sarcolemma
Muscle fiber degenerate into fatty tissue

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Atrophy

When muscle wastes away becoming smaller and weaker

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Disuse atrophy

Reduced number of nerve impulses, reversible. Ex bedridden, casts

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Degeneration atrophy

No nerve impulses to muscle at all. After 2 years irreversible. Muscle tissue will turn into fibrous c.t.

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Hypertrophy

Increased diameter of muscle fibers, increased number of mitochondria, myofibrils, Sr... Reversible

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Acetylcholine: acetylcholinesterase

Neurotransmitter: enzyme that breaks down the ACH

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Action potential: nerve impulse

Action p. Releases neurotransmitters : nerve impulse may not be strong enough to be turned into a.p.

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T. Tubule: terminal cisternae

A.p. Travels through here: Ca ions stores here. Together the traid works as a voltage sensor for muscle cell

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How would a drug interferes with cross bridge formation affect contraction?

Yes- no contraction occurs, you are paralyzed

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What would you expect to happen in resting skeletal muscle if the sarcolemma suddenly became very permeable to ca2+ ions

Sudden violent contraction, like a charley horse

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Predict what would happen to a muscle if he motor end plate did not contain acetyl cholinesterase

Muscle would contract one time only- could not be re-stimulated to contact a second time

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3 factors that are responsible for duration of muscle contraction

How long stimulation lasts at NMJ
Presence of Ca ions in the sarcoplasm
Availability of ATP

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Can a skeltal muscle contract without shortening?

Yes- isometric contraction has occured

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Tension rises to peak levels with very brief periods of relaxation

Incomplete tetanus

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One contraction one compete relaxation

Twitch

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Slightly higher tension results as a string of successive stimuli are received

Summation

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Stimulus frequency is so rapid that relaxation is completely eliminated

Complete tetanus

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How does a body sustain contractions?

Larger muscles like those of the back are controlled by more than one motor unit. Motor units are rotated so that some parts of the muscle are resting while other parts of the muscle are contracting. This results in a sustained contraction without fatigue of the overall muscle

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Acetylcholine

Contraction

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Acetylcholinesterase

Paralysis

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Anticholinesterase

Contraction

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Curare

Paralysis

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Botulin toxin

Paralysis

85

Tetanus infection

Paralysis

86

Polio infection

Paralysis

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The type of contraction in which tension rises, but resistance does not change is?

Isometric contraction

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An action potential can travel quickly from one cardiac muscle cell to another due to the presence of?

Intercalated disc

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What is a motor unit?

All muscle cells controlled by a single neuron-

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What forms of energy reserves do resting skeletal muscle fibers contain

Co, ATP, glycogen

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What two mechanisms are used to generate ATP in a muscle cell

Aerobic and anaerobic respiration

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Two activities that would require aerobic endurance

Distance sports- cords country and skiing

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Two areas of the boy where slow fibers

Eyeballs and muscles of the fingers

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Describe the relationship between lactic acid and fatigue

As lactic acid increase, pH of the sarcoplasm drops, enzymes will not work, therefore, muscle is fatigued and can no longer contract until homeostasis is regained

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You were orbiting the moon 6 months?

Disuse atrophy

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You were in an accident and needed bed rest for 2 months

Disuse atrophy

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You have been bulking up by drinking those gross protein shakes with creative

Hypertrophy

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What fiber in cheetah

White

99

Salmon?

Dark

100

Tilapia

White

101

Whale

Dark

102

Seal

White

103

Bear

Dark

104

Gastrocnemius muscle

Dark

105

Spasm

Sudden contraction of single m. In a larger m. group

106

Cramp

Painful spasm

107

Twitch

Single involuntary contraction

108

Tremor

Rhythmic, repeated contraction, produces shaking

109

Isometric

Building tension but muscle doesn't shorten

110

Isotonic

Build tension and he muscle shortens