Microscopic Structure of Skeletal Muscle Tissue Overview

Muscle Tissue Characteristics

• Conductivity is not a functional property that distinguishes muscle tissue from other tissues.

Skeletal Muscle Structure

• Layers of connective tissue in and around skeletal muscle are called epimysium, perimysium, and endomysium.
• The point of attachment that moves during muscle contraction is called the insertion.

Muscle Physiology

• Muscle weakness and degeneration are characteristics of muscular dystrophy.
• The main purpose of muscle tissue's property of conductivity is to allow rapid transmission of electrical impulses.
• During contraction, the muscle shortens to do work in isotonic contractions.

Muscle Contraction Mechanism

• Troponin blocks the myosin binding sites on actin when the muscle is at rest.
• Tropomyosin changes its shape in response to rising calcium concentration, exposing the myosin binding sites on actin.
• The nerve ending and muscle fiber meet at the neuromuscular junction.

Neurotransmission

• Acetylcholine is released into the synaptic cleft from the nerve terminal.

Calcium's Role

• Calcium is involved in muscle contraction by removing the blocking action of troponin and tropomyosin.
• Calcium ions bind to troponin, causing a conformational change that exposes the myosin binding sites on actin.

Sarcoplasmic Reticulum and T-Tubules

• The sarcoplasmic reticulum is a type of smooth endoplasmic reticulum that stores calcium ions.
• Terminal cisterns are specialized regions of the sarcoplasmic reticulum that store calcium ions.
• T-tubules (transverse tubules) are invaginations of the sarcolemma that allow rapid transmission of electrical impulses.

Muscle Function and Disease

• Delayed-onset muscle soreness (DOMS) is caused by micro-tears in muscle fibers.
• Fibromyalgia is diagnosed based on widespread pain in specific locations.
• Exercise can help speed up recovery from DOMS.
• Fibromyalgia is commonly managed with medication, including NSAIDs.
• NSAIDs are used to manage overused or strained postural muscles.

Muscle Types and Functions

• The primary tissue in the heart is cardiac muscle.
• Smooth muscle tissue helps in squeezing fluids through hollow organs.
• Actin and myosin filaments are responsible for shortening muscle cells.
• The prefix "myo-" means 'muscle'.
• Skeletal muscle tissue is striated and voluntary.
• Sphincter muscles control the opening and closing of hollow organs.
• The prefix "sarco-" means 'flesh'.
• Smooth muscle tissue has a fusiform appearance.
• Each muscle fiber is wrapped in a sheath of connective tissue called the epimysium.
• Nerves and blood vessels in skeletal muscles provide innervation and oxygenation.