ch 9 Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

muscle tissue

A

skeletal: skeletal, striated and voluntary; multinucleated, long, cylindrically shaped cells bundled together, contractions are fast but easily fatigue
cardiac muscle: cardiac, striated and involuntary. makes up muscular layer of the heart, uninucleated, cells branched with specialized junctions called intercalated discs; contractions rhythmic, fast, and completely relax in between contractions preventing fatigue.
smooth muscle: visceral, non-striated, and involuntary
narrow cylindrical fibers; makes up wall of blood vessels, ducts, hollow organs, uninucleated. closely arranged cells form sheets. contractions slow and sustained

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

function of muscle tissue

A
  1. produce body movement
  2. maintain posture and body position: ability to stand upright
  3. support soft tissue: layers of muscle make abdominal wall and floor of pelvic cavity
  4. guard entrances and exits
  5. maintain body temperature:heat released by working muscles
  6. store nutrient reserves: source of amino acids as energy reserve
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

properties of muscle tissue

A
  • -excitability or irritability: ability to receive and respond to stimulus
  • -contractility: ability to shorten forcibly when adequately stimulated
  • -extensibility: ability to be stretched or extended
  • -elasticity: ability to recoil and resume its resting length after being stretched
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

gross anatomy

A

each skeletal muscle is discrete organ made up several kinds of tissues
blood vessels, nerve fibers, connective tissue are also present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

nerve supply

A

somatic motor neuron –> skeletal muscle cant contract on its own.
each muscle served by one nerve, an artery and by one or more veins
microscopically each muscle fiber is supplied by one nerve ending

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

blood supply

A

contracting muscle uses a hug amount of energy

highly vascularized

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

connective tissue sheaths

A

epimysium: “overcoat” dense irregular connective tissue. connected or blends into the deep fascia; separates muscle from surrounding tissues and organs
perimysium: surrounds muscle fiber bundles called fascicles; contain dense irregular CT; blood vessels and nerves serve muscle fibers
endomysium: within the muscle; a delicate, flexible, elastic connective tissue layer (mostly reticular fibers)
surrounds each muscle fiber, loosely interconnects adjacent muscle fiber. contain: capillary networks, satellite cells and nerve cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

microscopic anatomy of skeletal muscle

A

the muscle fiber:
can be very long up to 12 in
develop through fusion of myoblasts: some myoblasts do not fuse and remain for tissue repair.
contain hundreds of nuclei

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

motor unit

A

motor neuron and skeletal muscle fibers innervated by that motor neuron’s axonal terminals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

thin filaments: 4 proteins

A
  1. F-actin (filamentous actin): two twisted rows of G-actin (globular actin), each which contain a myosin binding site
  2. nebulin: holds F-actin strands together, long nonelastic protein,; helps anchor thin filament ot z disc, regulates length of thin filament during development
  3. tropomyosin: double stranded protein molecule; covers myosin binding sites on actin; spirals around actin core and helps stiffen F-actin
  4. troponin: globular protein composed of 3 subunits. binds to tropomyosin G-actin, controlled by calcium ions
    TnT: binds to tropomyosin
    TnC: binds to calcium
    TnI: binds to actin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

relaxed muscle

A

normal shape of sarcomere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

contracted muscle

A

the A band stays the same width, but the z lines move closer together and the I band gets smaller, the sarcomere shorten simultaneously and the ends of the myofibril are pulled toward its center

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

partially relaxed

A

the i band partially gets shorter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

length and tension

A

length-tension relationship: resting length at time of stimulation: determines degree of overlap, therefore, number of pivoting cross-bridges
the number of cross-bridges largely determines the amount of tension produced
Frequency of stimulation: affects concentration of Ca2+ in the sarcoplasm and bound to troponin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

twitch

A

single stimulus-contraction-relaxation sequence in muscle fiber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

latent period

A

begins at stimulation and lasts 2 msec (excitation-contraction coupling is occuring)

17
Q

contraction period

A

tension rises to a peak contraction cycle begins 10-100 msec

18
Q

relaxation period

A

relaxation cycle begins lasts 10-100 msec

19
Q

treppe

A

stair-step increase in twitch tension

20
Q

wave summation

A

successive stimuli arrive before relaxation phase has been completed. duration of a single twitch determines max. time available for wave summation

21
Q

incomplete/ unfused tetanus

A

stimulus frequency increases further without allowing muscle to relax completely; tension rises further and reaches a peak

22
Q

complete/fused tetanus

A

stimulus frequency is so high, relaxation phase is eliminated and tension plateaus at max levels

23
Q

synchronous motor unit summation

A

all firing away at the same time for short period of time

peak tension occurs when all motor units in muscle contract in state of complete tetanus

24
Q

asynchronous motor unit summation

A

relay team; takes turns firing away gives longer lasting contraction
motor units are activated on a rotating basis some are resting and recovering while others contract

25
Q

muscle tone

A

normal tension and firmness of a muscle at rest

26
Q

isotonic: concentric isotonic contraction

A

peak muscle muscle tension exceeds th load, the muscle shortens which decreases angle at joint and moves object

27
Q

eccentric isotonic contraction

A

muscles elongates; very common and important

28
Q

isometric contraction

A

same measure no change

muscle as a whole does not shorten or change and results in no motion: peak tension never exceeds the load

29
Q

atp

A

provides energy; demands are great during muscle contraction. resting muscles only contain enough ATP to sustain a contraction until additional ATP can be generated.

30
Q

3 pathways to get ATP

A
  1. direct phosphorylation: coupled reaction of creatin phosphate and ADP: way to store energy; unique high energy molecule stored in muscles
  2. anaerobic pathways: glycolysis and lactic acid fermentation
  3. aerobic pathway