Muscle Physiology (REYNOLDS) Flashcards by Gavin Kallabat | Brainscape

Q

What are the 6 functions of skeletal muscles?

A

Produce skeletal movement
Maintain body position
Support soft tissues
Guard openings
Maintain body temperature
Store nutrient reserves

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Q

Muscles have three layers of connective tissue. What are they?

A

Epimysium, Perimysium and Endomysium

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Q

All of the following are true regarding the Epimysium EXCEPT:

A. Exterior collagen layer

B. Surrounds muscle fiber bundles (fascicles)

C. Connected to deep fascia

D. Separates muscle from surrounding tissues

E. None of the above

A

B. Surrounds muscle fiber bundles (fascicles)

Perimysium surrounds muscle fiber bundles

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Q

Which of the following is true regarding the Perimysium?

A. Surrounds individual muscle cells (muscle fibers)

B. Surrounds muscle fiber bundles (fascicles)

C. Connected to deep fascia

D. Separates muscle from surrounding tissues

E. None of the above

A

B. Surrounds muscle fiber bundles (fascicles)

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Q

Which of the following is true regarding the Endomysium?

A. Surrounds individual muscle cells (muscle fibers)

B. Surrounds muscle fiber bundles (fascicles)

C. Connected to deep fascia

D. Separates muscle from surrounding tissues

E. None of the above

A

A. Surrounds individual muscle cells (muscle fibers)

Epimysium = exterior collagen layer

Perimysium = surrounds muscle fiber bundles

Endomysium = surrounds individual muscle cells

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Q

Which of the following separates muscle from surrounding tissue?

A. Epimysium

B. Perimysium

C. Endomysium

A

A. Epimysium

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Q

Which of the following contains capillaries and nerve fibers contacting muscle cells?

A. Epimysium

B. Perimysium

C. Endomysium

A

C. Endomysium

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Q

Which of the following contains myosatellite cells (stem cells) that repair damage?

A. Epimysium

B. Perimysium

C. Endomysium

A

C. Endomysium

note: contains capillaries to help repair damage

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Q

Which of the following contains the blood vessels and nerves to supply the fascicles?

A. Epimysium

B. Perimysium

C. Endomysium

A

B. Perimysium

Perimysium surrounds muscle fiber bundles (fascicles)

Endomysium surrounds muscle fibers

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Q

Skeletal muscles fibers develop through fusion of mesodermal cells known as _____.

A

Myoblasts

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Q

List the 4 thin filament proteins:

A

F-actin
Nebulin
Tropomyosin
Troponin

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Q

All of the following are thin filament proteins EXCEPT:

A. Myosin

B. F-actin

C. Nebulin

D. Tropomyosin

E. Troponin

A

A. Myosin

Myosin and Titin = thick filament

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Q

Which of the following contain both myosin and actin filaments?

A. Z line

B. M line

C. A bands

D. I bands

A

C. A bands

A band = actin + myosin

I band = actin ONLY

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Q

Which of the following contain ONLY actin filaments?

A. Z line

B. M line

C. A bands

D. I bands

A

D. I bands

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Q

Which of the following do thick filaments contain?

(select all that apply)

A. Myosin

B. Troponin

C. Titan

D. Tropomyosin

A

A. Myosin

C. Titan

Thick filaments = Titan + Myosin

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Q

Which of the following holds F-actin strands together?

A. F-actin

B. Nebulin

C. Tropomyosin

D. Troponin

A

B. Nebulin

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Q

Which of the following is a globular protein that binds tropomyosin to G-actin and is controlled by Ca²⁺?

A. Myosin

B. Nebulin

C. Troponin

D. Titan

A

C. Troponin

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Q

Which of the following is double stranded and prevents actin-myosin interactions?

A. F-actin

B. Nebulin

C. Tropomyosin

D. Troponin

A

C. Tropomyosin

Q

Which of the following is two twisted rows of globular G-actin?

A. F-actin

B. Nebulin

C. Tropomyosin

D. Troponin

A

A. F-actin

note: the active sites on G-actin strands bind myosin

F-actin: two twisted rows of globular G-actin

Nebulin: holds F-actin strands together

Tropomyosin: prevents actin-myosin interactions

Troponin: binds tropomyosin to G-actin

Q

Discuss the sarcomere function:

A

Transverse tubules encircle the sarcomere near zones of overlap
Ca2+ released by SR causes thin and thick filaments to interact
Skeletal muscle contraction

Q

Discuss the Sliding filament theory:

A

Thin filaments of sarcomere slide toward M line, alongside thick filaments
The width of A zone stays the same
Z lines move closer together
The process of contraction
Neural stimulation of sarcolemma causes excitation-contraction coupling
Cisternae of SR release Ca2+, which triggers interaction of thick and thin filaments consuming ATP and producing tension initiating contraction
Ca2+ binds to receptor on troponin molecule

Q

Neural stimulation of the ________ causes excitation-contraction coupling.

A

Sarcolemma

Q

Discuss the process of skeletal muscle contraction:

A

Neural stimulation of sarcolemma causes excitation-contraction coupling
Cisternae of SR release Ca²⁺ which triggers interaction of thick and thin filaments consuming ATP and producing tension
Initiating contraction:
- Ca²⁺ binds to receptor on troponin molecule
- Troponin-tropomyosin complex changes exposing the active site of F-actin
Myosin action:
- “energized” myosin heads bind to actin forming cross-bridges
- myosin undergoes a conformational change termed “ratchet action” that pulls actin towards center of sarcomere
- myosin releases ADP
- binding of ATP to myosin decreases affinity of myosin for actin thus releasing myosin from actin

Q

Discuss the neuromuscular junction:

Where does it end at?
- What does the previous answer release?

A

Neuromuscular junction

ends at synaptic terminal
Synaptic terminal releases acetylcholine into the synaptic cleft (gap between synaptic terminal and motor end plate)

Q

Discuss the neural transmitter Acetylcholine (ACh):

A

Acetylcholine

travels along synaptic cleft
binds to motor end plate of sarcolemma
causes Na+ rush into sarcoplasm
is quickly broken down by acetylcholinesterase

Q

What are the 4 steps of acetylcholine in muscle contraction?

A

arrival of an action potential at the synaptic terminal
Release of ACh into synaptic cleft
Ach binding at motor end plate of synaptic cleft (causing Na+ to rush into the cell)
Appearance of an action potential in the sarcolemma (ACh is broken down by AChE at this step)

Q

An action potential is generated by an increase of ______ in the sarolemma.

A. Ca²⁺

B. ATP

C. Acetylcholine

D. Na⁺

E. K⁺

A

D. Na⁺

Q

What are the 5 main steps of the contraction cycle?

A

Exposure of active sites

Ca²⁺ binds to receptor on troponin
Troponin-tropomyosin complex changes exposing active site of F-actin

Formation of cross-bridges
* “energized” myosin head bind to underlying actin forming cross-bridges
Ratchet Action (pivoting) of myosin heads
* myosin undergoes conformation change termed “ratchet action” that pulls actin toward the center of the sarcomere
Detachment of cross-bridges

myosin releases ADP
binding of ATP to myosin decreases the affinity of myosin for actin, thereby releasing myosin from actin

Reactivation of myosin
* reactivation of myosin by partially hydrolyzing ATP

Q

______ is a fixed muscle contraction that occurs after death due to Ca²⁺ build up in sarcoplasm.

A

Rigor mortis

Q

Discuss the Cori Cycle:

A

The removal and recycling of lactic acid by the liver, which recharges muscle glycogen

Q

Which of the following contains myoglobin?

A. Slow fibers

B. Intermediate fibers

C. Fast fibers

D. All of the above

A

A. Slow fibers

Q

Which of the following contain intercalated discs?

A. Skeletal muscle

B. Cardiac muscle

C. Smooth muscle

D. All of the following

A

B. Cardiac muscle

Intercalated discs:

specialized contact points between cardiocytes that join cell membranes of adjacent cardiocytes (gap junctions, desmosomes)
Functions:
- maintain structure
- enhance molecular and electrical connections
- conduct action potentials

Q

What are the 4 functions of cadiac tissue?

A

Automacity

contraction w/o neural stimulation
controlled by pacemaker

Variable contraction tension
* controlled by nervous system
Extended contraction time
* 10 times as long as skeletal muscle
Prevention of wave stimulation
* long refractory periods

Q

Which of the following is nonstriated?

A. Skeletal muscle

B. Cardiac muscle

C. Smooth muscle

A

C. Smooth muscle

Q

What are the 8 charateristics of smooth muscle?

A

long, slender and spindle shaped
have single, central nucleus
have no T tubules, myofibrils or sarcomeres
Have no tendons or aponeuroses
have scattered myosin fibers
myosin fibers have more heads per thick filament
have thin filaments attached to dense bodies
dense bodies transmit contractions from cell to cell

Q

Which of the following contain a multiple nuclei?

A. Skeletal muscle

B. Cardiac muscle

C. Smooth muscle

A

A. Skeletal muscle

Cardiac and smooth muscle contain one centralized nuclei

Q

Which of the following contains calmodulin?

A. Skeletal muscle

B. Cardiac muscle

C. Smooth muscle

A

C. Smooth muscle

Q

_____ is a stair-step increase in twitch tension.

A

Treppe

repeated stimulations immediately after relaxation phase
causes a series of contractions with increasing tension

Q

Which of the following is characterized as fast oxidative?

A. Slow-twitch fibers

B. Intermediate fibers

C. Fast-twitch fibers

A

B. Intermediate fibers

Slow-twitch fibers = slow oxidative

Intermediate fibers = fast oxidative

Fast-twitch fibers = fast glycolytic

Q

Which of the following is characterized as fast glycolytic?

A. Slow-twitch fibers

B. Intermediate fibers

C. Fast-twitch fibers

A

C. Fast-twitch fibers

Q

Skeletal muscle develops tension but is prevented from changing length:

A. Isotonic contraction

B. Isometric contraction

A

B. Isometric contraction

“Iso” = same

“metric” = length

Q

Discuss Isotonic contraction:

does skeletal muscle change in length?
If muscle tension > load does the muscle shorten or lengthen?
_____ contraction is another term for muscles lengthening.

A

Isotonic contraction

skeletal muscle changes length resulting in motion
Muscle tension > load = muscle shortens
Muscle tension < load = muscle lengthens
Eccentric contraction is another term for muscles lengthening

Q

_______ occurs when twitches reach maximum tension.

A. Complete tetanus

B. Incomplete tetanus

A

B. Incomplete tetanus

Incomplete tetanus: twitches reach maximum

If rapid stimulation continues and muscle is not allowed to relax, twitches reach maximum level of tension

Complete tetanus: if stimulation frequency is high enough, muscle never begins to relax, and is in continuous contraction