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A and P I > Chapter 9 - Part 2 > Flashcards

Chapter 9 - Part 2 Flashcards

1
Q

The force exerted on the load
Contraction produces this

A

Muscle tension

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2
Q

Load is greater than maximum tension muscle can generate, no shortening of muscle

A

Isometric contraction

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3
Q

Muscle changes length and moves load
Actin filaments move towards center of sarcomere and cause movement
Concentric: muscle shortens, work done
Eccentric: muscle lengthens and generates force

A

Isotonic contraction

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4
Q

Each muscle is served by at least one _____

A

Motor nerve

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5
Q

As a motor neuron axon enters muscle, it branches into many _____

A

Endings

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6
Q

Each ending forms a ______ with a single muscle fiber

A

Neuromuscular junction

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7
Q

Consists of motor neuron and all of the muscle fibers it innervates (supplies)

A

Motor unit

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8
Q

Smaller the number of muscle fibers innervated _______

A

Greater fine control
More precise

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9
Q

Simplest form of contraction resulting from a muscle fiber’s response to a single action potential from motor neuron

A

Muscle twitch

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10
Q

Twitch recorded and observed as _____

A

Myogram

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11
Q

Line recording of myogram

A

Tracing

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12
Q

First phase of muscle twitch; events of excitation-contraction coupling
No muscle tension seen

A

Latent Period

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13
Q

Second phase of muscle twitch; cross bridge formation
Tension increases

A

Period of Contraction

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14
Q

Third phase in muscle twitch; Ca2+ reentry into SR
Tension declines to zero

A

Period of Relaxation

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15
Q

Differences in muscle strength and duration of twitches are due to variations in metabolic properties and ________

A

Enzymes

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16
Q

Muscle responses are graded by:

A
  1. Change in frequency of stimulation
  2. Change in strength of stimulation
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17
Q

Results if two stimuli are received by a muscle in rapid succession
Muscle fibers do not have time to completely relax between stimuli, so twitches increase in force with each stimulus

A

Wave (temporal) summation

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18
Q

Single stimulus results in single contractile response

A

Individual twitches

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19
Q

If stimuli frequency, muscle tension reaches near maximum
Produces smooth, continuous contractions that add up (summation)
Quivering contraction

A

Unfused tetanus

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20
Q

Stimuli frequency increases, muscle tension reaches maximum
Contractions “fuse” into one smooth sustained contraction
Leads to muscle fatigue

A

Fused tetanus

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21
Q

Stimulus send to more muscle fibers, leading to more precise control

A

Recruitment

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22
Q

Stimulus not strong enough, so no contractions seen

A

Subthreshold stimulus

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23
Q

Stimulus strong enough to cause a first observable contraction

A

Threshold stimulus

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24
Q

Strongest stimulus that increases maximum contractile force
All motor units have been recruited

A

Maximal stimulus

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25
Q

Recruitment works on ____
Motor units with smallest muscle fibers are recruited first
Largest motor units are activated only for most powerful contractions

A

Size principle

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26
Q

Some fibers contract while others rest

A

Asynchronous contraction

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27
Q

Constant, slightly contracted state of all muscles; Due to spinal reflexes
Keeps muscles firm, healthy, and ready to respond
Stabilizes joints and maintains posture

A

Muscle tone

28
Q
  1. Moves and detaches cross bridges
  2. Pumps calcium back into SR
  3. Pumps Na+ out and K+ back into cell after EC coupling
A

ATP

29
Q

Unique molecule located in muscle fibers that donates a phosphate to ADP to instantly form ATP

A

Creatine phosphate

30
Q

Enzyme that carries out transfer of phosphate

A

Creatine kinase

31
Q

Breaking down and using energy stored in nutrient molecules
Muscles use glucose from blood or glucose produces by first breaking down glycogen
1. Anaerobic respiration
2. Aerobic respiration

A

Cellular respiration

32
Q

Glycolysis and lactic acid formation

A

Anaerobic respiration

33
Q

First step in glucose breakdown
Broken into pyruvic acid
2 ATPs generated for each glucose

A

Glycolysis

34
Q

High intensity activities ______ oxygen availability
Bulging muscles compresses blood vessels, impairing oxygen delivery

A

Decreases

35
Q

Product of pyruvic acid break down in absence of oxygen

A

Lactic acid

36
Q

Which organ cells can convert lactic acid back into pyruvic acid?

A

Liver cells

37
Q

When oxygen is available, pyruvic acid enters mitochondria to start process
Produces 95% of ATP during rest and light to moderate exercise
Slower than anaerobic pathways
32 ATP per glucose

A

Aerobic respiration

38
Q

Physiological inability to contract despite continued stimulation;
Usually occurs when there are ionic imbalances (K+, Ca2+, P)
Lack of ATP rarely a reason for fatigue, except in severely stressed muscles

A

Muscle fatigue

39
Q

_____ of contraction depends on number of cross bridges attached

A

Force

40
Q

The more motor units recruited, the greater the force

A

Number of muscle fibers stimulated

41
Q

The bulkier the muscle, the more tension it can develop
Hypertrophy occurs with regular exercise

A

Relative size of fibers

42
Q

The higher the frequency, the greater the force
Stimuli are added together

A

Frequency of stimulation

43
Q

Muscle fibers with sarcomeres that are 80-120% their normal resting length generate more force (not stretched or shortened more)

A

Degree of stretch

44
Q

Exercise using oxygen, such as swimming, jogging, biking
More muscle capillaries, number of mitochondria, myoglobin synthesis
Results in increased muscle metabolism endurance, strength, resistance to fatigue

A

Aerobic endurance exercise

45
Q

Exercise such as weight lifting, isometric movements
Typically anaerobic
Muscle hypertrophy occurs, increased mitochondria, myofilaments, glycogen stores, and connective tissue
Results in muscle strength and size

A

Resistance training

46
Q

Muscle degeneration and loss of mass
Due to immobilization of muscle or loss of neural stimulation
Can begin almost immediately
Can decline 5% per day

A

Disuse atrophy

47
Q

Paralyzed muscles can shrink to 1/4th initial size
Fibrous connective tissue replaces lost muscle tissue

A

Muscle atrophy

48
Q

Variants of male sex hormone
testosterone
Involved in increasing muscle and bone mass during male puberty
Originally used to treat anemia

A

Corticosteroids (steroids)

49
Q

Side effects of steroids

A
50
Q

Found in walls of most hollow organs, except heart; Spindle-shaped fibers with one nucleus; Only connective tissue sheath is endomysium; No sarcomeres, myofibrils, T tubules; SR less developed than skeletal muscle

A

Smooth muscle

51
Q

Pouchlike infoldings of sarcolemma; Contain numerous Ca2+ channels that open to allow rapid influx of extracellular Ca2+

A

Caveolae

52
Q

Thick and thin filaments arranged _____

A

Diagonally

53
Q

Myofilaments arranged _______, allowing smooth muscle to contract like a corkscrew

A

Spirally

54
Q

Lattice like arrangement of noncontractile intermediate filaments that resist tension

A

Intermediate filament-dense body network

55
Q

Connect adjacent fibers; helps cells “talk” to one another

A

Gap junctions

56
Q

Proteins that anchor filaments to sarcolemma at regular intervals

A

Dense bodies

57
Q

Is tropomyosin involved in smooth muscle?

A

Yes

58
Q

Is troponin involved in smooth muscle?

A

No

59
Q

Protein that will bind to Ca2+ instead of troponin

A

Calmodulin

60
Q

Bulbous swellings on nerve fibers
Located on autonomic nerve fibers that innervate smooth muscle
Store and release neurotransmitters into a wide synaptic cleft

A

Varicosities

61
Q

Synaptic cleft in smooth muscle

A

Diffuse junction

62
Q

True or false; some smooth muscle cells have no nerve supply
(Some respond to both neural and chemical stimuli)

A

True

63
Q

Ca2+ binds to calmodulin, not troponin
Activated calmodulin then activates myosin kinase
Stopping smooth muscle contraction requires more steps than skeletal muscle

A

Differences between Smooth and Skeletal muscle contraction

64
Q

First (outermost) layer in smooth muscle; Fibers are parallel to long axis of organ
Contraction causes organ to shorten

A

Longitudinal layer

65
Q

Alternating contractions and relaxations of layers
Mixes and squeezes substances through lumen of hollow organs

A

Peristalsis

66
Q

Second layer in smooth muscle; Fibers run around circumference of organ

A

Circular layer

A and P I (18 decks)

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