Muscle Tissue Ch 9 Flashcards Preview

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Flashcards in Muscle Tissue Ch 9 Deck (53)
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1
Q

Skeletal Muscles

A

Organs that attach to and cover the skeleton
Have striations
Voluntary muscle

2
Q

Cardiac Muscle

A

Only in heart
Striated
Involuntary

3
Q

Smooth Muscle

A

In walls of hollow, visceral organs.
Nonstriated
Involuntary

4
Q

4 Characteristics of Muscle Tissue

A

Excitability
Contractility
Extensibility
Elasticity

5
Q

4 Major Muscle Functions

A

Movement
Posture
Stabilize joints
Generate heat

6
Q

Additional functions of muscle

A

Protect internal organs
Form valves
Dilate and constrict pupils
Arrector pili in hair follicles

7
Q

Nerve and blood supply

A

Generally 1 nerve, 1 artery, and 1 or more veins for each muscle.

8
Q

3 Connective tissue sheaths of muscle

A

Epimysium: Surround whole muscle
Perimysium: Surrounds each fascicle
Endomysium: wispy sheath that surrounds each muscle fiber

9
Q

Attachments

A

Direct: fleshy attachments, epimysium is attached directly to outside of bone or cartilage.
Indirect: more common, tissue extends beyond muscle as tendon or aponeurosis and anchors to bone or cartilage.

10
Q

Insertion

A

The attachment at the movable bone

11
Q

Origin

A

The attachment at the immovable or less movable bone.

12
Q

Sarcolemma

A

Plasma membrane

13
Q

Sarcoplasm

A

Cytoplasm of a muscle cell

Contains large amounts of glycosomes (glycogen) and myoglobin (oxygen).

14
Q

Myofibrils

A

80% of cellular volume

rod-like cylinders that run the length of the cell

15
Q

Sarcomere

A

smallest, contractile, functional unit of skeletal muscle.

16
Q

Striations

A

Dark and light bands that wrap around the myofibril.
Dark:A bands
Light: I bands

17
Q

Myofilaments

A

Smaller structures in sarcomeres: think and thin

18
Q

Thick filaments

A

Central
Myosin (red)
Length of A band

19
Q

Thin filaments

A

Lateral
Actin (blue)
Extend across I band into A band

20
Q

Tropomyosin

A

rob-shaped protein, spiral around the actin core. Stabilize it and block myosin-binding sites.

21
Q

Troponin

A

Globular-polypeptide complex
TnI: Inhibits, binds to actin
TnT: binds to tropomyosin, positions actin
TnC: binds calcium ions

22
Q

Elastic filiments

A
Giant protein titin
Extends from Z disc
Forms thick filament core
Holds think in place
Helps muscle spring back
23
Q

Sacroplasmic Reticulum

A

Interconnecting tubules surround each myofibril. Regulates calcium

24
Q

T Tubules

A
Transverse, at each A band I band junction
Increase muscle fibers surface area
continuous with extra cellular space
Encircle each sarcomere
Ensures synchronized contraction
25
Q

Terminal Cisterns

A

“end sacs”
Perpendicular cross channels at A-I band junctions
Involved in energy production

26
Q

Triad Relationship

A

T tubules, SR and Terminal Cisterns.
T-tubules: act as voltage sensors
SR: gated channels through which terminal cisterns release Ca2+

27
Q

Sliding filament model of contraction

A

During contraction thin filaments slide past thick so that the actin and myosin filaments overlap to a greater degree.

28
Q

Neuromuscluar junction (NMJ)

A

or end plate, is a synapse between a muscle cell and neuron. Only one per each muscle fiber, located midway.

29
Q

Acetylcholine

A

Neurotransmitter released into the synaptic cleft and open NA+ and K+ channels. Triggers action potential.

30
Q

Achetylcholinestrase

A

enzyme that breaks down ACh and prevents continues muscle fiber contraction.

31
Q

Excitation-Contraction Coupling (E-C)

A
  1. AP moves along sarcolemma & down T tubules
  2. Ca ions are released
  3. Ca bind to troponin & removes tropomysin
  4. Contraction begins
32
Q

Cross bridge cycle

A
  1. Cross bridge forms, myosin head attached to actin
  2. Power stroke, myosin bends and pulls actin towards M line, low energy
  3. Cross bridge breaks, ADP attaches and weakens link
  4. Cocked position, myosin returns to high energy state.
33
Q

Muscle tension

A

Isometric: load does not move
Isotonic: Load moves

34
Q

Motor unit

A

One or more neurons and all the muscle fibers it supplies.

35
Q

Muscle twitch

A

Muscles responce to single action potential

  1. Latent period:first few ms after stimulation
  2. Period of contraction: peak tension
  3. Period of relaxation: reentry of Ca into SR muscle tension returns to 0
36
Q

Graded muscle response

A

Variations needed for proper control of muscle contractions

37
Q

Muscle response to changes in stimulus frequancy

A
  • Single stimulus =single twitch
  • unfused tetanus wave/temporal summation: second contraction begins before the first begins
  • Fused tetanus: no relaxation between frequencies.
38
Q

Muscle response to changes in stimulus strength

A
  • Sub-threshold: no response
  • Threshold: contracts more and more as stimulus increases.
  • Maximal: strongest & all motor unit muscles are recruited
39
Q

Two Isotonic contractions

A

Concentric: muscle shortens and does work
Eccentric:muscle generates force as it lengthens.

40
Q

Muscle tone:

A

Involuntary muscle contraction that maintains posture and protects joints.

41
Q

3 ways to provide energy for contraction

A
  1. Direct phosphorylation
  2. Anaerobic pathway
  3. Aerobic pathway
42
Q

Direct Phosphorylation

A

Coupled reaction of Creatine Phosphate and ADP
Uses no O2,
Creates 1 ATP
Lasts 15 seconds

43
Q

Anaerobic pathway

A

Glycolysis & Lactic acid formation
No O2 needed
1 ATP per glucose
Lasts 30-40 seconda

44
Q

Aerobic pathway

A

Cellular respiration
Uses O2
Produces 32 APT per glucose
Lasts hours

45
Q

Muscle fatigue

A

Inability to contract.

46
Q

For muscles to return to resting state:

A
  1. O2 reserves replenished
  2. Lactic acid converted to pyruvic acid
  3. Glycogen stores replaced
  4. ATP and CP replaces
47
Q

Excess Postexercise Oxygen Consumption (EPOC)

A

Extra O2 the body needs to restore (Oxygen debt)

48
Q

Heat production

A

40% of energy is converted into useful work and the rest is lost as heat.

49
Q

Force of muscle contraction

A
  1. Number of muscles stimulated
  2. Size of fibers
  3. Frequency of stimulation
  4. Degree of muscle stretch
50
Q

Muscle fiber types

A

Slow oxidative fibers
Fast oxydative fibers
Fast glycolytic fibers

51
Q

Slow Oxydative Fibers

A
For endurance activities
Contracts slowly
Uses O2
Fatigue resistant
small and red with many mitochondria and capillaries
52
Q

Fast Oxydative Fibers

A
For Sprinting
Contracts fast
Mostly Aerobic
red/pink, medium size
Many mitochondria and capillaries
53
Q

Fast Glycolytic Fibers

A
Short-term intense movements 
Fast contraction
Anaerobic glycolysis
Fast fatigue
White, Large
Few mitochondria and capilaries