Page 3 Flashcards
What causes increased muscle mass?
Increased production of myofibrils, mitochondria, sarcoplasmic reticulum, and other organelles due to very forceful, repetitive muscular activity, such as strength training.
What is muscular fibrosis?
The replacement of muscle fibers by fibrous scar tissue due to muscle damage or degeneration.
What is muscular atrophy?
A decrease in size of individual muscle fibers as a result of progressive loss of myofibrils.
What is disuse atrophy?
Atrophy that occurs because muscles are not used, with a greatly reduced flow of nerve impulses to inactive skeletal muscle, but the condition is reversible.
What is denervation atrophy?
Atrophy that occurs if nerve supply is disrupted or cut, resulting in irreversible replacement by fibrous connective tissue.
What is rigor mortis?
A state of muscle rigidity where muscles cannot contract or stretch due to calcium ion leakage from the sarcoplasmic reticulum into the sarcoplasm, allowing myosin heads to bind to actin. It lasts 3-4 hours after death and about 48 hours in total.
What is hypotonia?
Decreased or lost muscle tone.
Flaccid paralysis is characterized by loss of muscle tone, loss or reduction of tendon reflexes, and atrophy and degeneration of muscles.
What is hypertonia?
Increased muscle tone.
Spasticity is characterized by increased muscle tone (stiffness) associated with an increase in tendon reflexes and pathological reflexes. Rigidity is increased muscle tone in which reflexes are not affected.
What is myasthenia gravis?
An autoimmune disease causing chronic, progressive damage of the neuromuscular junction due to antibodies blocking ACh receptors, leading to muscle weakness and fatigue. Initial symptoms include weakness of eye and throat muscles, progressing to difficulty chewing and talking.
What is Duchenne Muscular Dystrophy (DMD)?
A condition commonly occurring in males due to a mutated gene on the X chromosome that codes for dystrophin, leading to muscle fiber rupture and death.
What is a spasm?
A sudden involuntary contraction of a single muscle in a large group of muscles.
What is a cramp?
A painful spasmodic contraction.
It may be caused by inadequate blood flow, overuse, dehydration, injury, prolonged positions, or low blood levels of electrolytes, such as potassium.
What is a tic?
A spasmodic twitching made involuntarily by muscles that are ordinarily under voluntary control.
What is a tremor?
A rhythmic, involuntary, purposeless contraction that produces a quivering or shaking movement.
What is fasciculation?
An involuntary, brief twitch of an entire motor unit that is visible under the skin, occurring irregularly and not associated with the movement of the affected muscle.
What is fibrillation?
A spontaneous contraction of a single muscle fiber that is not visible under the skin but can be recorded by electromyography.
Fibrillations may signal destruction of motor neurons.
