Types Of Muscles Flashcards
Muscle Tissue
Function of all three major types of muscle is integral to function of the entire body
All three types of muscle tissue provide the movement necessary for survival
Muscles maintain the body in a relatively stable position
Cardiac Muscle
Found only in the heart
Striated involuntary muscle
Unique features related to its function:
- Each cardiac muscle contains parallel myofibrils
- Syncytium: Continuous, electrically coupled mass
Smooth muscle
composed of small, tapered cells that have a single nucleus
Ca2+ comes from outside the cell and binds to calmodulin instead of troponin to trigger a contraction
No striations
Two types of smooth muscle tissue
Single-unit (visceral) smooth muscle and multi-unit smooth muscle
Single-unit (visceral) smooth muscle
- Gap junctions join smooth muscle fibres into large, continuous sheets
- Is autorhythmic and produces peristalsis
Multi unit smooth muscle
Composed of many independent single-cell units
Can form thin sheets, such as the walls of large blood vessels
Characteristics of skeletal muscle cells
Excitability: ability to be stimulated
Contractility: ability to contract, or shorten, and produce body movement
Extensibility: ability to extend, or stretch, thereby allowing muscles to return to their resting length
Muscle Cells
Fibres (due to thread like shape)
Sarcolemma
plasma membrane of muscle fibres
Sarcoplasmic reticulum
T tubules: network of tubules and sacs found within muscle fibres
Membrane of the sarcoplasmic reticulum continually pumps Ca?+ from the sarcoplasm and stores the ions for later release
T tubules
Muscle Cell components
Contains many mitochondria and several nuclei. Myofibrils: numerous fine fibres packed close in sarcoplasm.
Sarcomere
Contractile unit of muscle fires
Each myofibril consists of many sarcomeres
Striated muscle
Dark stripes called A bands; light H band runs across the midsection of each dark A band
Light stripes called I bands; dark Z disk extends across the centre of each light I band
Triad
Triplet of tubules; a T tubule sandwiched between two sacs of sarcoplasmic reticulum
Myofilaments
Each myofibril contains thousands of thick and thin myofilaments
Proteins that make up myofilaments
Myosin
Makes up almost all the thick filaments
myosin “heads” are known as cross bridges when attached to actin
Actin
globular protein that forms two fibrous strands twisted around each other to form the bulk of the thin filament
Tropomyosin
protein that blocks the active sites on in molecules
Troponin
protein that holds tropomyosin molecules in place
Acetylcholine (ACh)
neurotransmitter released into the synaptic cleft that diffuses across the gap, stimulates the receptors and initiates an impulse in the sarcolemma
Rotator cuff
Rotator cuff is a group of muscles and tendons that surround the shoulder joint, keeping the head of your upper arm bone firmly within the shallow socket of the shoulder
Isotonic contraction
Tone or tension in a muscle remains the same as the length of the muscle changes
Isometric contraction
Muscle length remains the same while muscle tension increases