Discuss anatomy and physiology if skeletal muscle?

Skeletal muscle is a type of muscle tissue that is attached to bones and is responsible for voluntary movements of the body. It is made up of long, cylindrical cells called muscle fibers that are bundled together in groups called fascicles. These fascicles are further bundled together to form the entire muscle.

Anatomy of skeletal muscle:
- Each muscle fiber is surrounded by a connective tissue sheath called the endomysium.
- Several muscle fibers are grouped together into bundles called fascicles, which are surrounded by a connective tissue sheath called the perimysium.
- The entire muscle is surrounded by a connective tissue sheath called the epimysium.
- Tendons are tough, fibrous connective tissues that attach muscles to bones.

Physiology of skeletal muscle:
- Skeletal muscle is under voluntary control, meaning that it can be consciously controlled by the nervous system.
- When a muscle is stimulated by a nerve impulse, it contracts and generates force, allowing movement to occur.
- The basic functional unit of a muscle fiber is the sarcomere, which is made up of overlapping filaments of actin and myosin proteins.
- When a muscle contracts, the actin and myosin filaments slide past each other, causing the sarcomere to shorten and the muscle to contract.
- Skeletal muscle also plays a role in maintaining posture, stabilizing joints, and generating heat through the process of shivering.

Overall, the anatomy and physiology of skeletal muscle work together to allow for movement and support of the body. The intricate structure of muscle fibers and the coordinated contraction of sarcomeres enable the body to perform a wide range of movements with precision and control.

Anatomy of Skeletal Muscle

Structure:

- Composed of cylindrical muscle fibers bundled together into fascicles
- Each fascicle is surrounded by a layer of connective tissue called the perimysium
- Fascicles are grouped into bundles called muscle bellies, which are covered by a thicker layer of connective tissue called the epimysium
- Individual muscle fibers are surrounded by a thin membrane called the sarcolemma

Internal Structure:

- Myofibrils: Long, thin protein filaments arranged in repeating units called sarcomeres
- Sarcomeres are the contractile units of muscle
- Myofilaments: Two types of protein filaments involved in muscle contraction: actin and myosin

Physiology of Skeletal Muscle

Excitation-Contraction Coupling:

- An electrical impulse from a nerve triggers the release of calcium ions from the sarcoplasmic reticulum (SR)
- Calcium ions bind to troponin molecules on the actin filaments, causing them to expose myosin-binding sites
- Myosin heads bind to actin, forming cross-bridges

Muscle Contraction:

- Myosin heads pivot, pulling the actin filaments toward the center of the sarcomere
- This sliding action shortens the sarcomere, leading to muscle contraction

Muscle Relaxation:

- When the electrical impulse ends, calcium ions are actively pumped back into the SR
- Calcium removal from troponin causes the actin-myosin cross-bridges to break
- The muscle fiber relaxes

Muscle Types:

- Slow-twitch fibers (type I):
- Fatigue-resistant
- Rich in mitochondria and blood vessels
- Used for sustained contractions
- Fast-twitch fibers (type II):
- Fatigue more quickly
- Less mitochondria and blood vessels
- Suitable for brief, powerful contractions

Muscle Metabolism:

- Aerobic respiration: Utilizes oxygen to produce ATP, primarily in slow-twitch fibers
- Anaerobic respiration: Utilizes glycogen to produce ATP without oxygen, leading to lactate production in fast-twitch fibers

Control of Muscle Function:

- The nervous system sends electrical impulses to specific muscle fibers, allowing for precise control
- Hormones such as epinephrine and norepinephrine can also influence muscle function
- Factors such as training, nutrition, and age can affect muscle size, strength, and endurance