Muscle Tissue Lecture Notes

Flashcards for reviewing muscle tissue lecture notes.

Function of Muscle Tissue

Movement of the body and movement of internal materials

Other functions of Muscle Tissue

Posture maintenance, stabilization of joints, protection of internal organs, temperature regulation

Excitability

Responds to changes in electrical potentials across the cell membrane

Involuntary Muscle Control

Unconsciously controlled muscles (smooth and cardiac muscle)

Voluntary Muscle Control

Consciously controlled muscles (skeletal muscle)

Extensibility

Can stretch or extend

Elasticity

Can stretch and return to original shape

Contractility

Can pull on attachment site and shorten

Skeletal Muscle

Long, multinucleated cells; cylindrical shape; striated

Cardiac Muscle

One or two nuclei; shorter, branching cells; striated

Smooth Muscle

One nucleus; spindle-shaped; non-striated

Location of Cardiac Muscle

Walls of the heart

Appearance of Cardiac Muscle

Striated fibers like skeletal muscle

Shape of Cardiac Muscle Fibers

Shorter, branching fibers

Cardiac Muscle Control

Involuntarily controlled

Location of Smooth Muscle

Found in internal organs

Striations in Smooth Muscle

Non-striated

Filaments in Smooth Muscle

Thick and thin filaments present, but not regularly arranged

Shape of Smooth Muscle Cells

Spindle-shaped cells

Nuclei in Smooth Muscle Cells

Single nucleus

Control of Smooth Muscle Contraction

Involuntary

Thin filaments

Anchored by dense bodies in smooth muscle

Source of Calcium in Smooth Muscle

Sarcoplasmic reticulum and extracellular fluid

Calcium Binding in Smooth Muscle

Binds to calmodulin and activates myosin kinase

Myosin Head Action in Smooth Muscle

Activated myosin heads bind to and pull thin filaments

Epimysium

Surrounds entire muscle

Fascia

Additional layer of CT external to epimysium

Perimysium

Surrounds fascicles

Fascicles

Bundles of muscle cells

Endomysium

Surrounds individual muscle cells

Sarcolemma

Cell membrane of muscle cell

Sarcoplasm

Cytoplasm of muscle cell

Sarcoplasmic Reticulum (SR)

Endoplasmic reticulum that stores calcium

Transverse Tubules (T-tubules)

Extensions of sarcolemma

Myofibrils

Cylinders of contractile proteins

Neuromuscular Junction

Point of contact between a motor neuron and skeletal muscle

Neurotransmitter Released at NMJ

Acetylcholine (ACh)

Sliding Filament Model

Describes how a sarcomere shortens

Calcium's Role in Muscle Contraction

Binds to troponin, initiating muscle contraction

Excitation-Contraction Coupling

Connects muscle action potential and muscle fiber contraction

Resting Membrane Potential

-90 mV

End Plate Potential

Occurs when sodium ions enter through receptors at the end plate

Sources of ATP for Muscle Contraction

Creatine phosphate, glycolysis, and aerobic respiration

Creatine Phosphate

Donates phosphate to ADP to regenerate ATP

Muscle Fatigue

Occurs when muscle can no longer contract

Three Types of Muscle Fibers

Slow oxidative (SO), fast glycolytic (FG), and fast oxidative (FO)

Isometric Contraction

Muscle contracts but does not move a load

Concentric Contraction

Muscle shortens to move a load