Introduction to Muscle Contraction and Fiber Types

Practice flashcards covering muscle contraction patterns, toxins, motor units, and fiber types based on the lecture notes.

Wave Summation

A pattern of contraction where a muscle fiber is stimulated before the previous twitch has ended, resulting in the building of tension to a maximum level.

Tetanus

A condition occurring when every cell in a muscle is contracting at its maximum tension without any relaxation phase.

Clostridium tetani

A bacterium found in soil and manure that produces a toxin causing muscles to enter complete tetanus, leading to conditions like lockjaw.

Masseter Muscles

The strongest muscles in the body, often the first to seize up during a tetanus infection, a condition known as lockjaw.

Clostridium botulinum

A bacterium that thrives in improperly canned goods and produces a toxin that prevents muscles from contracting, potentially causing death by paralyzing the diaphragm.

Botox

A medical application of the botulism toxin used to paralyze muscles for cosmetic reasons or to treat conditions like migraine headaches and profuse sweating.

Treppe

A stepwise pattern of contraction observed in cardiac muscle where the muscle is allowed to completely relax between stimulations occurring less than $50$ times a second.

Motor Unit

A single motor neuron and all of the muscle cells it controls, which determines the precision and force of muscle movement.

Recruitment

The process of increasing the number of active motor units to smoothly increase muscle tension and prevent fatigue by rotating through different units.

Muscle Tone

The normal firmness or tension in a muscle at rest, maintained by constant background electrical stimulation from the brain.

Hypotonia

A condition caused by brain, spinal cord, or neuron damage that leads to an absence of muscle tone and flaccid paralysis.

Hypertonia

A condition where the nervous system keeps a muscle in a state of constant contraction, leading to spastic paralysis as seen in Parkinson's disease.

Fast Glycolytic Fibers

Large, pale muscle fibers that produce quick, strong bursts of energy through glycolysis but fatigue rapidly due to fewer mitochondria and low oxygen supply.

Slow Oxidative Fibers

Small, dark red muscle fibers that use aerobic metabolism to produce energy, making them slower to contract but highly resistant to fatigue.

Myoglobin

A pigment in muscle cells with a high binding affinity for oxygen, responsible for giving slow oxidative fibers their dark red color.

Gastrocnemius

The calf muscle used for walking and running, primarily composed of slow oxidative fibers for endurance.

Sarcopenia

The natural process of muscle shrinking that begins between ages $20$ and $30$ and accelerates after age $50$.

Fibrosis

The replacement of damaged muscle tissue with collagen as one ages, resulting in muscles that are less elastic and more prone to fat deposition.