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

Chapter 9 - Part 2 Flashcards

(66 cards)

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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
Recruitment works on ____ Motor units with smallest muscle fibers are recruited first Largest motor units are activated only for most powerful contractions
Size principle
26
Some fibers contract while others rest
Asynchronous contraction
27
Constant, slightly contracted state of all muscles; Due to spinal reflexes Keeps muscles firm, healthy, and ready to respond Stabilizes joints and maintains posture
Muscle tone
28
1. Moves and detaches cross bridges 2. Pumps calcium back into SR 3. Pumps Na+ out and K+ back into cell after EC coupling
ATP
29
Unique molecule located in muscle fibers that donates a phosphate to ADP to instantly form ATP
Creatine phosphate
30
Enzyme that carries out transfer of phosphate
Creatine kinase
31
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
Cellular respiration
32
Glycolysis and lactic acid formation
Anaerobic respiration
33
First step in glucose breakdown Broken into pyruvic acid 2 ATPs generated for each glucose
Glycolysis
34
High intensity activities ______ oxygen availability Bulging muscles compresses blood vessels, impairing oxygen delivery
Decreases
35
Product of pyruvic acid break down in absence of oxygen
Lactic acid
36
Which organ cells can convert lactic acid back into pyruvic acid?
Liver cells
37
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
Aerobic respiration
38
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
Muscle fatigue
39
_____ of contraction depends on number of cross bridges attached
Force
40
The more motor units recruited, the greater the force
Number of muscle fibers stimulated
41
The bulkier the muscle, the more tension it can develop Hypertrophy occurs with regular exercise
Relative size of fibers
42
The higher the frequency, the greater the force Stimuli are added together
Frequency of stimulation
43
Muscle fibers with sarcomeres that are 80-120% their normal resting length generate more force (not stretched or shortened more)
Degree of stretch
44
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
Aerobic endurance exercise
45
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
Resistance training
46
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
Disuse atrophy
47
Paralyzed muscles can shrink to 1/4th initial size Fibrous connective tissue replaces lost muscle tissue
Muscle atrophy
48
Variants of male sex hormone testosterone Involved in increasing muscle and bone mass during male puberty Originally used to treat anemia
Corticosteroids (steroids)
49
**Side effects of steroids**
50
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
Smooth muscle
51
Pouchlike infoldings of sarcolemma; Contain numerous Ca2+ channels that open to allow rapid influx of extracellular Ca2+
Caveolae
52
Thick and thin filaments arranged _____
Diagonally
53
Myofilaments arranged _______, allowing smooth muscle to contract like a corkscrew
Spirally
54
Lattice like arrangement of noncontractile intermediate filaments that resist tension
Intermediate filament-dense body network
55
Connect adjacent fibers; helps cells "talk" to one another
Gap junctions
56
Proteins that anchor filaments to sarcolemma at regular intervals
Dense bodies
57
Is tropomyosin involved in smooth muscle?
Yes
58
Is troponin involved in smooth muscle?
No
59
Protein that will bind to Ca2+ instead of troponin
Calmodulin
60
Bulbous swellings on nerve fibers Located on autonomic nerve fibers that innervate smooth muscle Store and release neurotransmitters into a wide synaptic cleft
Varicosities
61
Synaptic cleft in smooth muscle
Diffuse junction
62
True or false; some smooth muscle cells have no nerve supply (Some respond to both neural and chemical stimuli)
True
63
Ca2+ binds to calmodulin, not troponin Activated calmodulin then activates myosin kinase Stopping smooth muscle contraction requires more steps than skeletal muscle
Differences between Smooth and Skeletal muscle contraction
64
First (outermost) layer in smooth muscle; Fibers are parallel to long axis of organ Contraction causes organ to shorten
Longitudinal layer
65
Alternating contractions and relaxations of layers Mixes and squeezes substances through lumen of hollow organs
Peristalsis
66
Second layer in smooth muscle; Fibers run around circumference of organ
Circular layer
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