AnaPhy Lecture Flashcards
System Functions
- Movement
- Posture maintenance
- Respiration
- Body heat production
- Communication
- Organ & vessel constriction
The ability of muscle to shorten forcefully or contract
Contractility
The capacity of muscle to respond to a stimulus
Excitability
The ability to stretched beyond its normal resting length and still be able to contract
Extensibility
The ability of the muscle to recoil to its original resting length after it has been stretched
Elasticity
Surrounds each skeletal muscle
Epimysium/Muscular Fascia/Muscle Fascia
Surrounds the muscle fasciculi/muscular fasciculi/fasciculi
Perimysium
Surrounds the muscle fibers
Endomysium
Cell membrane of muscle fibers
Sarcolemma
- Closely associated with the T-tubules
- High Ca2+ concentration
Sarcoplasmic Reticulum
- Enlarged portions
- Two terminal cisternae and their associated T tubule form a muscle triad
Terminal Cisternae
- Tubelike inward foldings along the sarcolemma
- Connect the sarcolemma to the sarcoplasmic reticulum.
Transverse (T) Tubules
- Cytoplasm of the muscle fiber
- Contains numerous myofibrils
Sarcoplasm
A.k.a. thin filaments
Actin Myofilament
Two strands twisted together, have attachment sites for the myosin myofilaments
Actin
Molecules attached at specific intervals along the actin myofilaments - Have binding sites for Calcium (Ca2+)
Troponin
- Located between the twisted actin strands
- Block the myosin myofilament binding sites on the actin myofilaments in an unstimulated muscle
Tropomyosin
A.k.a. thick myofilaments
Resemble bundles of golf clubs.
Myosin Filament
- Parts of the myosin molecule that resemble golf club heads
- The heads can bind to attachment sites on the actin myofilament
- Can bend and straighten during contraction
- Can break down ATP to release energy.
Myosin Head
- The cell membrane (sarcolemma) is polarized
- Charge difference between the outside (positively charged) and inside (negatively charged) of the cell membrane
Resting Membrane Potential
- This is due to More Sodium (Na +) ions outside the cell membrane
More Potassium (K+) ions inside the cell membrane - Some Na+ channels close thus trapping some negatively charged particles inside the cell. For these reasons, the inside of the cell membrane is more negatively charged than the outside of the cell membrane.
Resting Membrane Potential
- A stimulation in a muscle fiber or nerve cell causes Na+ channels to open quickly, making the membrane to become very permeable to Na+ for a brief time.
- This causes an influx of Na+ ions, causing the inside of the cell membrane to become more positive than the outside of the cell.
Depolarization
- Near the end of depolarization, Na+ channels close and K+ channels open
- The tendency for Na+ to enter the cell decreases, and the tendency for K+ to leave the cell increases.
Repolarization
- Causes changes in membrane potential to aid in cell-to-cell communication
- 1-3 seconds
Action Potential
