Chapter 10 muscle tissue

Skeletal Muscle

Skeletal Muscle

Muscle responsible for movement, heat production, and posture; it is voluntary and attached to skeletal bones.

Cardiac Muscle

Muscle that pumps blood through systemic, pulmonary, and coronary circulation; found in the heart wall and is involuntary.

Smooth Muscle

Muscle involved in peristalsis in the GI tract, capable of contraction to propel food; involuntary and located in internal organs, blood vessels, skin, and airways.

Voluntary Muscle

Muscle that is under conscious control; includes skeletal muscle.

Involuntary Muscle

Muscle that operates without conscious control; includes cardiac and smooth muscle.

Electrical Excitability

The ability of muscle tissue to respond to stimuli by producing electrical signals called action potentials.

Contractility

The ability of muscular tissue to contract forcefully when stimulated.

Extensibility

The ability of muscular tissue to stretch without being damaged.

Elasticity

The ability of muscular tissue to return to its original length and shape after contraction or extension.

Fascia

A sheet or band of dense fibrous connective tissue surrounding muscles and organs.

Superficial Fascia

Also known as the subcutaneous layer, separates muscle from skin and provides insulation and protection.

Deep Fascia

Connective tissue that lines the body wall and limbs, holding muscles with similar functions together.

Epimysium

The outermost layer of dense irregular connective tissue that surrounds the belly of a muscle.

Perimysium

Layer of dense, irregular connective tissue that surrounds groups of muscle fibers, forming fascicles.

Endomysium

Connective tissue that penetrates the interior of each fascicle, surrounding individual muscle fibers.

Tendon

A cord of dense connective tissue that attaches muscle to the periosteum of a bone.

Aponeurosis

A broad, flat tendon that serves to attach muscle to bone or other muscles.

Myoblasts

Immature muscle cells that fuse to form skeletal muscle fibers during embryonic development.

Triad

A structure formed by one transverse tubule and two terminal cisterns in a muscle fiber.

Sarcomere

The main contractile unit of a skeletal muscle fiber, defined by Z lines and containing actin and myosin.

A Band

The dark region of a sarcomere where thick myosin filaments are present.

I Band

The light region of a sarcomere where thin actin filaments are present.

Z Line

The boundary structure of a sarcomere that anchors actin filaments.

H Band

The region in the A Band where there is no overlap of actin and myosin filaments.

M Line

The middle line of the sarcomere that holds thick filaments together.

Actin

Thin filaments in a sarcomere that play a key role in muscle contraction.

Myosin

Thick filaments in a sarcomere that interact with actin to facilitate contraction.

Sliding Filament Mechanism

The process where actin filaments slide over myosin filaments during muscle contraction.

ATP Hydrolysis

The breakdown of ATP into ADP and a phosphate group, providing energy for muscle contraction.

Cross-Bridge Formation

The attachment of a myosin head to an actin filament, allowing contraction to occur.

Power Stroke

The step during muscle contraction where the myosin head pivots and pulls the actin filament toward the M line.

Detachment of Myosin

The process where myosin heads release actin due to the binding of ATP.

Excitation-Contraction Coupling

The physiological process where an action potential leads to calcium release from the sarcoplasmic reticulum.

Neuromuscular Junction

The synapse between a somatic motor neuron and a skeletal muscle fiber.

Synaptic Cleft

The gap between a neuron and a muscle fiber where neurotransmitters are released.

Acetylcholine (ACh)

A neurotransmitter released at the neuromuscular junction that initiates muscle contraction.

Motor Unit

A single somatic motor neuron and all the muscle fibers it innervates.

Twitch Contraction

A measured response of muscle to a single stimulus comprising several phases: latent, contraction, relaxation, and refractory periods.

Isotonic Contraction

Muscle contraction that results in a change in muscle length while tension remains constant.

Isometric Contraction

Muscle contraction where the muscle length remains unchanged while tension increases.

Concentric Contraction

Muscle contraction where the muscle shortens as it contracts.

Eccentric Contraction

Muscle contraction where the muscle lengthens while contracting.

Slow Oxidative Fiber

Type of skeletal muscle fiber that contracts slowly and is resistant to fatigue.

Fast Oxidative Glycolytic Fiber

Type of skeletal muscle fiber that can contract quickly and is moderately resistant to fatigue.

Fast Glycolytic Fiber

Type of skeletal muscle fiber that contracts rapidly but fatigues quickly.

Creatine Phosphate

A molecule that provides a rapid way to regenerate ATP in muscle fibers, particularly in the first 15 seconds of activity.

Anaerobic Glycolysis

The process of ATP production without oxygen, primarily producing energy for short bursts of activity.

Cellular Respiration

The process of producing ATP through aerobic metabolism, including the Krebs cycle and electron transport chain.

Calcium Ions (Ca2+)

Ions essential for initiating muscle contractions by facilitating the interaction between actin and myosin.

Sodium Ions (Na+)

Ions that play a crucial role in generating action potentials in muscle fibers.

Acetylcholine Receptors

Specific receptors on the motor end plate that bind acetylcholine to initiate muscle contraction.

Tension-Length Relationship

The relationship between the length of a sarcomere and the tension it can produce during contraction.

Optimal Length

The ideal sarcomere length that allows maximal tension production.

Muscle Fatigue

A condition characterized by a decline in ability of a muscle to generate force.

Fascicles

Bundles of muscle fibers surrounded by perimysium.

Sarcoplasmic Reticulum

Specialized endoplasmic reticulum in muscle fibers that stores calcium ions.

Somatic Motor Neuron

A neuron that stimulate skeletal muscle fibers to contract

Synaptic Vesicles

Membrane-bound structures in nerve endings that store neurotransmitters.

Periosteum

The dense connective tissue layer that surrounds bones, to which tendons attach.

T-tubules

Transverse tubules that help conduct action potentials deep into muscle fibers.

Triad Structure

A functional arrangement of T-tubules and terminal cisterns in skeletal muscle.

Muscle Action Potential

An electrical impulse that initiates muscle contraction.

Relaxation Period

The phase where calcium is actively transported back into the sarcoplasmic reticulum and muscle tension decreases.

Refractory Period

The time after muscle contraction when excitability decreases and the muscle cannot contract again immediately.

Multiunit Smooth Muscle

Type of smooth muscle where cells act independently; found in large arteries and airways.

Single-Unit Smooth Muscle

Type of smooth muscle where fibers are interconnected and contract as a unit; found in the walls of organs like the intestines.