Flashcards in Muscle Tissue Ch 9 Deck (53):
Organs that attach to and cover the skeleton
Only in heart
In walls of hollow, visceral organs.
4 Characteristics of Muscle Tissue
4 Major Muscle Functions
Additional functions of muscle
Protect internal organs
Dilate and constrict pupils
Arrector pili in hair follicles
Nerve and blood supply
Generally 1 nerve, 1 artery, and 1 or more veins for each muscle.
3 Connective tissue sheaths of muscle
Epimysium: Surround whole muscle
Perimysium: Surrounds each fascicle
Endomysium: wispy sheath that surrounds each muscle fiber
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.
The attachment at the movable bone
The attachment at the immovable or less movable bone.
Cytoplasm of a muscle cell
Contains large amounts of glycosomes (glycogen) and myoglobin (oxygen).
80% of cellular volume
rod-like cylinders that run the length of the cell
smallest, contractile, functional unit of skeletal muscle.
Dark and light bands that wrap around the myofibril.
Light: I bands
Smaller structures in sarcomeres: think and thin
Length of A band
Extend across I band into A band
rob-shaped protein, spiral around the actin core. Stabilize it and block myosin-binding sites.
TnI: Inhibits, binds to actin
TnT: binds to tropomyosin, positions actin
TnC: binds calcium ions
Giant protein titin
Extends from Z disc
Forms thick filament core
Holds think in place
Helps muscle spring back
Interconnecting tubules surround each myofibril. Regulates calcium
Transverse, at each A band I band junction
Increase muscle fibers surface area
continuous with extra cellular space
Encircle each sarcomere
Ensures synchronized contraction
Perpendicular cross channels at A-I band junctions
Involved in energy production
T tubules, SR and Terminal Cisterns.
T-tubules: act as voltage sensors
SR: gated channels through which terminal cisterns release Ca2+
Sliding filament model of contraction
During contraction thin filaments slide past thick so that the actin and myosin filaments overlap to a greater degree.
Neuromuscluar junction (NMJ)
or end plate, is a synapse between a muscle cell and neuron. Only one per each muscle fiber, located midway.
Neurotransmitter released into the synaptic cleft and open NA+ and K+ channels. Triggers action potential.
enzyme that breaks down ACh and prevents continues muscle fiber contraction.
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
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.
Isometric: load does not move
Isotonic: Load moves
One or more neurons and all the muscle fibers it supplies.
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
Graded muscle response
Variations needed for proper control of muscle contractions
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.
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
Two Isotonic contractions
Concentric: muscle shortens and does work
Eccentric:muscle generates force as it lengthens.
Involuntary muscle contraction that maintains posture and protects joints.
3 ways to provide energy for contraction
1. Direct phosphorylation
2. Anaerobic pathway
3. Aerobic pathway
Coupled reaction of Creatine Phosphate and ADP
Uses no O2,
Creates 1 ATP
Lasts 15 seconds
Glycolysis & Lactic acid formation
No O2 needed
1 ATP per glucose
Lasts 30-40 seconda
Produces 32 APT per glucose
Inability to contract.
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
Excess Postexercise Oxygen Consumption (EPOC)
Extra O2 the body needs to restore (Oxygen debt)
40% of energy is converted into useful work and the rest is lost as heat.
Force of muscle contraction
1. Number of muscles stimulated
2. Size of fibers
3. Frequency of stimulation
4. Degree of muscle stretch
Muscle fiber types
Slow oxidative fibers
Fast oxydative fibers
Fast glycolytic fibers
Slow Oxydative Fibers
For endurance activities
small and red with many mitochondria and capillaries
Fast Oxydative Fibers
red/pink, medium size
Many mitochondria and capillaries