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Anatomy & Physiology 1 > Exam 3: Muscle Tissue > Flashcards

Exam 3: Muscle Tissue Flashcards

1
Q

How does the muscular system produce motion?

A

Contraction and relaxation of muscles

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2
Q

Functions of muscle tissue

A 
Produce skeletal movement
Stabilize posture and body position
Support soft tissues
Guard entrances and exits 
Maintain body temperature 
Store nutrient reserves
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3
Q

Properties of muscle tissue

A

Electrical excitability
Contractility
Extensibility
Elasticity

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4
Q

The ability to respond to internal or external stimuli by producing action potentials

A

Electrical excitability

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5
Q

The ability to contract when stimulated by an action potential

A

Contractility

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6
Q

The ability to stretch without being damaged

A

Extensibility

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7
Q

The ability to return to original shape and size after contraction or extension

A

Elasticity

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8
Q

Types of muscle tissue

A

Skeletal muscle
Cardiac muscle
Smooth muscle

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9
Q

Skeletal muscle

A

Associated with skeleton and skin
Striated
Mainly voluntary control

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10
Q

Cardiac muscle

A

Located in heart
Striated
Involuntary control

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11
Q

Smooth muscle

A

Located in walls of hollow internal structures (respiratory, circulatory, digestive systems, etc. ) and in skin
Non-striated
Involuntary control

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12
Q

Also called muscle fibers because of their elongated shape

A

Muscle cells

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13
Q

What are the connective tissue components of skeletal muscle?

A

Fascia
Tendons
Deep fascia

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14
Q

Sheet of connective tissue surrounding a muscle

A

Fascia

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15
Q

Connects muscle to skin

A

Superficial fascia

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16
Q

Connects muscle to muscle or muscle to bone

A

Deep fascia

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17
Q

Extensions of connective tissue (fascia) that attach a skeletal muscle to the periosteum of a bone

A

Tendons

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18
Q

Deep fascia is underlaid by 3 other layers of connective tissue which are:

A

Epimysium
Perimysium
Endomysium

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19
Q

Connective tissue that surrounds the entire muscle

A

Epimysium

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20
Q

Connective tissue that surrounds groups of 10-100 muscle fibers and separates them into bundles, or fascicles

A

Perimysium

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21
Q

Connective tissue that surrounds and separate individual muscle fibers within a fascicle

A

Endomysium

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22
Q

How does the muscle tissue get nerve and blood supply?

A
  • Somatic motor neurons stimulate muscles. Each neuron has branches that extend to individual muscle fibers.
  • Each muscle supplied by one artery and one or two veins. Associated with a capillary bed that extends to all muscle fibers
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23
Q

What is the embryonic origin of muscle fibers?

A

Arise from fusion of myoblasts in embryo

24
Q

Plasma membrane of muscle fibers

A

Sarcolemma

25
Q

Invaginations of the sarcolemma extending from surface of muscle fiber inward; Open to outside of cell and Filled with interstitial fluid

A

Transverse tubules

26
Q

Cytoplasm of muscle fibers
Richly supplied with glycogen
Richly supplied with myoglobin

A

Sarcoplasm

27
Q

Extends length for muscle fiber
Contractile organelles of skeletal muscle fibers
Striated

A

Myofibril

28
Q

Surrounds myofibril and is a system of fluid filled membranous sacs, similar to smooth ER; stores Ca2+

A

Sarcoplasmic reticulum

29
Q

2 types of protein filaments that compose myofibrils

A

Thick and thin filaments

30
Q

Functional unit of myofibril, and compartments where filaments are arranged

A

Sarcomeres

31
Q

Each thick filament is surrounded by ____ thin filaments.

A

Two

32
Q

Regions of the sarcomere

A 
A band
I band
Zone of overlap
Z disc
H zone
M line
33
Q

Extends length of thick filaments

A

A line

34
Q

Region with thin filaments only

A

I line

35
Q

Region of overlap between thick and thin filaments

A

Zone of overlap

36
Q

Region found through center of each I band

A

Z disc

37
Q

Region with thick filaments only

A

H zone

38
Q

Region that support proteins linking thick filaments

A

M line

39
Q

Myofibrils include which proteins?

A

Contractile protein - generates force during contraction
Regulatory protein - switch contraction process on and off
Structural protein - keep thick and thin filaments in alignment

40
Q

Two contractile proteins

A

Myosin and actin

41
Q

Main component of thick filaments
Functions as motor protein
Includes tail and two “heads”
Converts chemical energy of ATP into mechanical energy of motion (production of force)

A

Myosin

42
Q

Main component of thin filaments

Functions as anchor point for myosin

A

Actin

43
Q

Two regulatory proteins

A

Troponin and tropomysin

44
Q

Where do regulatory proteins occur?

A

Thin filament

45
Q

Overview of sliding filament mechanism

A
  • Muscles get shorter (during contraction) or longer (during relaxation) because thick and thin filaments side past one another
  • Myosin heads bind to actin in thin filaments and “walk” along thin filaments, pulling thin filaments toward M line
  • Sarcomeres contract
46
Q

Contraction cycle (just be familiar with it)

A
  1. ) Contraction cycles begins
    - Myosin head is already energized
    - Ca2+ ions enter myofibril
  2. ) Active-site exposure
    - Ca2+ binds to troponin
    - Troponin pulls troponin myosin away from active sites of actin
  3. ) Cross-bridge formation
    - Energized myosin heads bind to active sites of actin
    - Forming cross-bridges between thick and thin filaments
  4. ) Myosin head pivoting
    - Myosin head pivoted toward M line during power stroke
    - ADP and phosphate group are released
  5. ) Cross-bridge detachment
    - Another ATP binds to myosin head
    - Myosin head detaches from active site of actin
    - Cross-bridge is broken
  6. ) Myosin reactivation
    - Free myosin head cleaves phosphate group from ATP
    - Myosin head becomes energized
47
Q

Describe the excitation-contraction coupling.

A

Increase of Ca2+ conc. in cytosol triggers muscle contraction

Sarcoplasmic reticulum releases Ca2+ into cytosol via Ca2+ release channels

Ca2+ release channels open in response to a muscle action potential (electrical excitation)

48
Q

Nerve action potential propagating triggers a muscle action potential via a ____________.

A

Neurotransmitter

49
Q

Synapse between neuron and muscle fiber

A

Neuromuscular junction (NMJ)

50
Q

Neurotransmitter responsible for communication across NMJ

A

Acetylcholine

51
Q

Describe the events at the NMJ

A
  1. ) ACh packaged in vesicles at synaptic end bulb of neuron
  2. ) Action potential reaches synaptic end bulb of neuron
  3. ) Action potential triggers release of ACh into synaptic cleft via exocytosis
  4. ) ACh diffuses across synaptic cleft and binds to receptors in sarcolemma of muscle fiber
    - Na+ channels in sarcolemma open, and Na+ enters sarcoplasm
  5. ) Acetylcholinesterase (AChE) breaks down ACh
52
Q

What breaks down ACh?

A

Acetylcholinesterase (AChE)

53
Q

Force of contraction of a muscle varies due to:

A

Nutrient and oxygen availability
Frequency of stimulation (rate at which action potentials arrive at NMJ)
Amount of stretch before contraction
Number of muscle fibers contracting

54
Q

Contraction of all muscle fiber in response to one nerve action potential

A

Twitch contraction

55
Q

Three phases of the twitch contraction

A

Latent period
Contraction period
Relaxation period

56
Q

What happens when there are 20-30 action potentials per second?

A

Incomplete (unfused) tetanus
Sustained but wavering contraction
Muscle fibers can’t completely relax between stimuli

57
Q

What happens when there are 80-100 action potentials per second?

A

Complete (fused) tetanus
Sustained, unwavering contraction
Muscle fibers can’t relax at all between stimuli

Anatomy & Physiology 1 (9 decks)

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