AP_1_-_Muscular_System_fall_2020

Muscular System Functions

1. Movement 2. Posture 3. Joint stabilization 4. Generating heat.

Types of Muscle Tissue

1. Skeletal 2. Smooth 3. Cardiac.

Skeletal Muscle

Striated and voluntary muscle tissue that builds the skeletal muscles moving bones.

Smooth Muscle

Unstriated and involuntary muscle tissue that forms walls of hollow organs.

Cardiac Muscle

Striated and involuntary muscle tissue found in the walls of the heart.

Excitability

The ability of muscle tissue to receive and respond to a stimulus.

Contractility

The ability of muscle tissue to shorten and generate force.

Myofibril

Contractile organelles in muscle cells that are divided into sarcomeres.

Sarcomere

The basic contractile unit of muscle, composed of myofilaments.

Myofilaments

Thick and thin protein fibers that slide to produce muscle contraction.

Tendon

A direct attachment where a muscle’s epimysium is fused to a bone’s periosteum.

Aponeurosis

An indirect attachment that is a sheet-like connection.

Sarcoplasmic Reticulum (SR)

A series of tubules that encloses stored calcium ions in muscle fibers.

Action Potential

The nerve signal that travels along a neuron to trigger muscle contraction.

Neuromuscular Junction

The site where a motor neuron’s axon meets a skeletal muscle fiber.

Acetylcholine (ACh)

The neurotransmitter used at neuromuscular junctions to trigger muscle contractions.

Cross Bridge Cycle

The cycle involving attachment, pivoting, and detachment of myosin heads to actin during contraction.

Rigor Mortis

The stiffening of muscles post-mortem due to calcium influx and lack of ATP.

Motor Unit

A single motor neuron and all the muscle fibers it controls.

Muscle Twitch

The response of muscle fibers to a single action potential.

Isotonic Contractions

Contractions that involve a change in muscle length during contraction.

Isometric Contractions

Contractions that do not involve a change in muscle length.

Anaerobic Respiration

A quick process that generates few ATP without oxygen.

Calcium and Cross Bridge Formation

Process where calcium binds to troponin to expose myosin binding sites on actin.

Sliding Filament Theory

Explanation that muscle contractions occur as thick and thin filaments slide past each other.

Disorders of the Muscular System

Conditions such as Myasthenia gravis and Duchenne Muscular Dystrophy that impact muscle function.