Muscle Tissue Ch 9 Flashcards Preview

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

Skeletal Muscles

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

2

Cardiac Muscle

Only in heart
Striated
Involuntary

3

Smooth Muscle

In walls of hollow, visceral organs.
Nonstriated
Involuntary

4

4 Characteristics of Muscle Tissue

Excitability
Contractility
Extensibility
Elasticity

5

4 Major Muscle Functions

Movement
Posture
Stabilize joints
Generate heat

6

Additional functions of muscle

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

7

Nerve and blood supply

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

8

3 Connective tissue sheaths of muscle

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

9

Attachments

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

Insertion

The attachment at the movable bone

11

Origin

The attachment at the immovable or less movable bone.

12

Sarcolemma

Plasma membrane

13

Sarcoplasm

Cytoplasm of a muscle cell
Contains large amounts of glycosomes (glycogen) and myoglobin (oxygen).

14

Myofibrils

80% of cellular volume
rod-like cylinders that run the length of the cell

15

Sarcomere

smallest, contractile, functional unit of skeletal muscle.

16

Striations

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

17

Myofilaments

Smaller structures in sarcomeres: think and thin

18

Thick filaments

Central
Myosin (red)
Length of A band

19

Thin filaments

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

20

Tropomyosin

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

21

Troponin

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

22

Elastic filiments

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

23

Sacroplasmic Reticulum

Interconnecting tubules surround each myofibril. Regulates calcium

24

T Tubules

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

Terminal Cisterns

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

26

Triad Relationship

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

27

Sliding filament model of contraction

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

28

Neuromuscluar junction (NMJ)

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

29

Acetylcholine

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

30

Achetylcholinestrase

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

31

Excitation-Contraction Coupling (E-C)

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

32

Cross bridge cycle

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

Muscle tension

Isometric: load does not move
Isotonic: Load moves

34

Motor unit

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

35

Muscle twitch

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

Graded muscle response

Variations needed for proper control of muscle contractions

37

Muscle response to changes in stimulus frequancy

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

38

Muscle response to changes in stimulus strength

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

39

Two Isotonic contractions

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

40

Muscle tone:

Involuntary muscle contraction that maintains posture and protects joints.

41

3 ways to provide energy for contraction

1. Direct phosphorylation
2. Anaerobic pathway
3. Aerobic pathway

42

Direct Phosphorylation

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

43

Anaerobic pathway

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

44

Aerobic pathway

Cellular respiration
Uses O2
Produces 32 APT per glucose
Lasts hours

45

Muscle fatigue

Inability to contract.

46

For muscles to return to resting state:

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

47

Excess Postexercise Oxygen Consumption (EPOC)

Extra O2 the body needs to restore (Oxygen debt)

48

Heat production

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

49

Force of muscle contraction

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

50

Muscle fiber types

Slow oxidative fibers
Fast oxydative fibers
Fast glycolytic fibers

51

Slow Oxydative Fibers

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

52

Fast Oxydative Fibers

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

53

Fast Glycolytic Fibers

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