12-MUSCLE Flashcards
Muscle functions
- Responsible for locomotion and movement of the different parts of the body
- Maintain an erect or seated position, or posture * Convert chemical energy to mechanical energy * Produce heat in the body
is the tendency of muscle cells to shorten significantly.
Contractility
is a muscle’s capacity to extend
Extensibility
is the tendency to rebound upon contracting.
Elasticity
is the ability to react to a stimulation that a hormone or motor neuron may deliver.
Excitability
Staining of muscle cells is
acidophilic or pinkish
The unit structure of muscles is ___________ in shape which is an adaptation to its function of ______
elongated
contraction
Sarcoplasm appears fibrillar due to its contents of
myofibrils
Cells are bound together by varying amounts of _________ containing blood vessels and nerves
areolar connective tissue
is responsible for muscle cell contraction
Myofilament
two types of Myofilament
Thick and thin
thin filaments are _____ in diameter and ___ long and composed primarily of the protein _____
6 to 8 nm in diameter, 1.0 um long
actin
thick filaments are _____ in diameter and ___ long and composed primarily of the protein _____
15 nm in diameter, 1.5 um long
mysosin II
Types of muscle tissue
Skeletal muscle
Cardiac muscle
Smooth muscle
is composed of bundles of very cylindrical, long, multinucleated cells that show striations cross
Skeletal muscle
Skeleteal muscle Contraction
quick, forceful, and usually under voluntary control
has cross-striations and is composed of elongated, branched individual cells that lie parallel to each other
Cardiac muscle
Cardiac muscle Contraction
involuntary, vigorous, and rhythmic
consists of collections of fusiform cells that do not show striations
Smooth muscle
Smooth muscle Contraction
process is slow and not subject to voluntary control
the cytoplasm of muscle cells and fibers which is acid in staining
Sarcoplasm
cell membrane complex
Sarcolemma
granules in the cytoplasm which under the electron microscope is actually mitochondrion
Sarcosome
fine threadlike structures in the sarcoplasm which is responsible for muscle contraction
Myofibrils
a linear unit
Sarcomere
refers to endoplasmic reticulum
Sarcoplasmic reticulum
Skeletal muscle consists of muscle fibers, which are
long, cylindrical multinucleated cells with diameters of 10–100 um
- Skeletal muscle nuclei characteristics
Long oval
Found in periphery of cell under cell membrane
Development of Skeletal Muscle
Myoblasts align and fuse together to make longer, multinucleated tubes called myotubes
Myotubes differentiating continue to form functional myofilaments and the nuclei are displaced against the sarcolemma
are unfused myeloblasts population located on the external surface of muscle fibers inside the developing external lamina
Satellite cells
these cells proliferate and produce new muscle fibers following muscle injury
Satellite cells
are responsible for the formation of primary myotubes, chainlike structures stretching between tendons of the developing muscle.
Early myoblasts
allow secondary myotubes to grow in the innervated region of muscle growth where the myotubes have close contact with nerve terminals.
Late myoblasts
increase cell volume
Hypertrophy
increase number of cells
Hyperplasia
dense connective tissue that enclosed the entire skeletal muscle
Epimysium
wraps each fascicle of muscle fibers
Perimysium
delicate layer which surrounds muscle fibers individual (elongated multinuclear cells)
Endomysium
Basis of Muscle Fiber Types Classification
Contractile speed
Velocity of the myosin ATPase reaction
Metabolic profile
defines how easily fiber can contract and relax.
Contractile speed
determines the rate at which this enzyme will break down ATP molecules during the contraction process.
Velocity of the myosin ATPase reaction
reveals the ability of the oxidative phosphorylation or glycolysis to generate ATP
Metabolic profile
Muscle Fiber types
I, IIa, IIb
Type I or slow, red oxidative fibers Metabolic profile
many mitochondria
abundant myoglobin and cytochrome complexes.
Red fibers (Type I) derive energy primarily from
aerobic oxidative phosphorylation of fatty acids
Type I fivers Contractile speed.
are slow-twitch, fatigue-resistant motor units