Muscle Tissue Flashcards
What is a sarcomere?
Repeating (intracellular) functional unit of striated muscle
What are the characteristics of muscle tissue?
- Cellular
- some CT Vascular - blood vessels
- Specialized to contract
Classifications of muscle
Skeletal Cardiac Smooth
What percentage of body mass is skeletal muscle?
40-50 %
How many muscles are on the human body?
639
Which muscles have sarcomeres and which do not?
Skeletal and cardiac have sarcomeres. Smooth does not
What are the characteristics of skeletal muscle?
Muscle fiber - multinucleated - filled with microfibrils, therefore nuclei are pushed to the side - cross striation due to sarcomeres Adapted for speed - moves skeleton and maintains posture - produces body heat 40-50% body mass is skeletal muscle
What are the 3 major functions of muscle?
Produce movement Produce heat Provide stability and maintain posture
What muscle in the body is controlled by consciousness?
Skeletal
Skeletal muscle function
Contraction
What is epimysium?
dense irregular connective tissue that encases each fiber and surrounds the whole skeletal muscle. name means “outside the muscle”
What is perimysium?
loose connective tissue that encases bundle of fibers (fasicles)
What is endomysium?
Loose connective tissue that encases each fiber
What is a tendon?
the 3 sheaths are continuous with each other. they all merge together to form the tendon, which is the connective tissue structure that joins skeletal muscles to bones.
What is skeletal muscle tissue?
located in the skeletal muscles. muscles cells are striated, innervated by voluntary division and is subject to conscious control.
What is cardiac muscle tissue?
occurs only in the wall of the heart. muscle cells are striated, but contraction is involuntary.
What is smooth muscle tissue?
found in the wall of hollow internal organs other than the heart, such as the stomach, urinary bladder, blood vessels, etc. Smooth muscle tissue lacks striations.
What are myofibrils?
unbranched cylinders making up over 80% of the sarcoplasm. Specialized contractile organelles unique to muscle tissue. Contain myofilaments. Myofibrils are composed of repeating segments called sarcomeres.
What are sarcomeres?
repeating intracellular functional unit of striated muscle. basic unit of contraction in skeletal muscle.
What is the structure of a sarcomere?
- Boundaries at 2 ends of sarcomere are called Z lines - Attached to each Z line and extending toward the center of the sarcomere are fine myofilaments (thin actin). Thin filaments are composed mainly of contractile protein (actin) - In the center of the sarcomere and overlapping the inner ends of the thin filaments is a bundle of thick (myosin) filaments. Thick filaments consists largely of myosin molecules.
Describe the structure of a sarcomere?
A Band- dark band created by the full length of the thick filaments in the sarcomeres, along with inner ends of thin filaments H Zone- central part of A band where no thin filaments reach I- regions that contain only thin filaments, create the light portions of the patterned striations. Z Disc- zig zag line, boundaries/two ends of each sarcomere
What is a thick filament?
comprised mostly of myosin molecules. Also contain ATPase enzymes that release energy for muscle contraction
What is a thin filament?
composed primarily of contractile protein actin.
what is a myofilament?
protein filaments (actin and myosin) arranged into sarcomeres- they do not form sarcomeres.
what is a muscle fiber?
elongated cylindrical (multinucleated) skeletal muscle cells. surrounded by the endomysium.
What is the belly comprised of in skeletal muscle organs?
Muscle fibers and CT proper
What is the tendon in skeletal muscle organs comprised of?
CT proper
What are the components of deep fascia?
Epimysium, perichondrium, periosteum
What is superficial fascia?
Subcutaneous
What are characteristics of cardiac muscle?
- single nucleus - intercalated discs- desmosome-like junctions between fibers; parallel to cross striations, located at z lines
What are the parts of intercalated discs?
1) macula adherens: junction between fibers 2) gap junction (nexus): allows electrical signal to pass from one myocardial to next
What are the characteristics of smooth muscle?
- Assorted for endurance and strength - very slow acting - involuntary - spindle shaped cells - no cross striations - composted of actin and myosin
