quiz 1 Flashcards
Tonic
Continual partial contraction; i.e. posture
Isotonic
Muscle shortens but it’s tension increases; produce movement
Isometric
Muscle length stays the same with increasing tension; no movement
Twitch
Quick, jerky contraction in response to single stimulus; rare
Tetanic
Sustained smooth contraction produced by a series of stimuli
Treppe
Staircase phenomenon; muscles contract more forcefully after they have contracted a few times
Fibrillation
Abnormal contraction where different muscle fibers contract at different times causing a “flutter”
Convulsion
Uncoordinated tetanic contractions of varying groups of muscles
General functions of muscular system
- Movement
- Posture
- Heat production
Reasons for names
- It’s action
- Direction of fibers
- It’s location
- Number of divisions
- It’s shape, size
- It’s points of attachment
Characteristics of skeletal muscle tissue
- voluntary
- cells are called fibers
- fibers are arranged in bundles called fascicles
- Striated
- Attached to bones via tendons
- Supply the strongest contraction
- mostly protein composed of filaments
- many nuclei per fiber
- many mitochondria per fiber
- will fatigue
- all or nothing law
- graded response during contraction
sarcolemma
cell membrane of muscle fiber
sacroplasm
cytoplasm of muscle fiber
sacroplasmic reticulum
analogous but not identical to endoplasmic reticulum of cells other than muscle fibers
myofibrils
numerous fine fibers packed close together in sarcoplasm
sarcomere
section of myofibril extending from one Z like to the next; each myofibril consists of many sarcomeres
thick filaments
composed of myosin molecules; heads of myosin molecules help form cross bridges for contraction
thin filaments
composed of actin, tropomyosin, and troponin molecules arranged in a complex fashion; alternate in myofibrils
contraction
thick and thin filaments combine forming cross bridges. thin. filaments are pulled toward middle of sarcomere.
origin
does not move