Muscular System Flashcards
What are the important functions of the muscular system?
Mobility, posture, and movement
The muscular system is essential for voluntary and involuntary movements.
What types of muscles are involved in voluntary movements?
Skeletal muscles
Skeletal muscles are attached to bones and facilitate body movements.
What type of muscle is under autonomic control and is involuntary?
Cardiac muscle and smooth muscle
These muscles function without conscious control.
What response occurs when thermoreceptors detect a drop in temperature?
The shivering reflex
This reflex involves smooth muscle contractions to generate heat.
What is the role of valves in the peripheral veins?
Prevent backflow of blood
They ensure unidirectional blood flow toward the heart.
What effect does muscle contraction have on blood flow?
Increases blood flow toward the heart
Muscle contraction compresses veins, enhancing blood return.
What is the shape and nucleus count of a skeletal muscle myocyte?
Cylinder-shaped and has many nuclei
This structure contributes to the muscle’s striated appearance.
Where is smooth muscle tissue found?
Walls of hollow organs and vessels
Smooth muscle aids in the movement of substances such as food and blood.
What is the shape and nucleus count of smooth muscle cells?
Spindle-shaped and uninucleate
Smooth muscle fibers are non-striated.
What is the structure of cardiac muscle cells?
Branched, striated, usually uninucleate
Cardiac muscle cells may have two nuclei and are interconnected by intercalated discs.
What role do T-tubules play in muscle contraction?
Help depolarize the cell and carry impulses to the sarcoplasmic reticulum
T-tubules are invaginations of the sarcolemma with high concentrations of ion channels.
What is the function of the sarcoplasmic reticulum (SR)?
Stores and releases calcium ions
The SR is specialized smooth endoplasmic reticulum surrounding myofibrils.
What is a sarcomere?
Basic within muscle tissue specialized for contraction
Sarcomeres consist of actin and myosin filaments.
What happens to the filaments during muscle contraction?
They slide over each other without changing length
Myosin heads pull on thin filaments causing sarcomeres to shorten.
What are the three main types of skeletal muscle fibers?
- Slow-twitch oxidative (SO type I)
- Fast-twitch oxidative-glycolytic (FOG type IIa)
- Fast-twitch glycolytic (FG type IIb)
The proportions of these fibers vary depending on muscle function.