Muscle (*) Flashcards
what are the 3 types of muscle?
skeletal muscle, cardiac muscle and smooth muscle
describe skeletal muscles
is composed of large, elongated, multinucleated fibers that show strong, quick, voluntary contractions
describe cardiac muscles
composed of irregular branched cells bound together longitudinally by intercalated discs and shows strong, involuntary contractions
describe smooth muscle
composed of grouped, fusiform cells with weak, involuntary contractions. The density of intercellular packing seen reflects the small amount of extracellular connective tissue present
An entire skeletal muscle is enclosed within a thick layer of dense connective tissue called the ________
epimysium
Large muscles contain several _____ each wrapped in a thin but dense connective tissue layer called the ________
fascicles, perimysium
Within fascicles individual muscle fibers (elongated multinuclear cells) are surrounded by a delicate connective tissue layer, the __________
endomysium
endomysium, perimesium and epimysium contains _________
collagen type I and II
reticulin
a giemsa stain with polarized light can reveal what is muscle?
network of capillaries in endomysium surrounding muscle fibers
what is the myotendinous junction?
Tendons develop together with skeletal muscles and join muscles to the periosteum of bones. The collagen fibers of a tendon are continuous with those in the connective tissue layers around muscle fibers, forming a strong unit that allows muscle contraction to move the skeleton
________ are cylindrical bundles of thick and thin myofilaments that fill most of each muscle fiber
Myofibrils
that each muscle fiber contains several parallel bundles called _________
myofibrils.
Each myofibril consists of a long series of ________, separated by Z discs and containing thick and thin filaments that overlap in certain regions.
sarcomeres
Thick filaments are bundles of myosin, which span the entire A band and are bound to proteins of the M line and to the Z disc across the I bands by a very large protein called________, which has springlike domains.
titin
Thin filaments are actin filaments with one end bound to ________ in the Z disc
α-actinin
A thick myofilament contains 200-500 molecules of ______
myosin
A thin filament contains ________ _________ and_________
F-actin, tropomyosin, and troponin.
Transverse tubules are invaginations of the _________ that penetrate deeply into the muscle fiber around all myofibrils.
sarcolemma
what is the rolde of componants of the triad?
cyclic release of Ca2+ from the cisternae and its sequestration again that occurs during muscle contraction and relaxation
______ _______ -________under acidic conditions reveals slow type oxidative fibers (type I)- darkest. Fast, oxidative-glycolytic (Type IIa) have intermediate staining. Fast, glycolytic fibers (Type IIb) have weakest staining.
ATPase enzyme histochemistry
in general what is the function of muscle?
contraction
in general what is the organization of skeletal muscle?
fascicles surrounded by connective tissue banding pattern from sacromeres
the transverse tubule system is for
AP propagation
the sarcoplasmic reticulum is used to ?
store calcium
what is the mechanism of contraction
Sliding filament theory, Calcium
innervation icnludes
motor neuron, motor end plate, excitation-contraction coupling.
name the muscle fibre types and relative stain speed?
slow oxidative (Type I), intermediate oxidative-glycolytic (Type IIa), fast, glycolytic (Type IIb).
What are intercalated discs?
fibers consist of separate cells in a series with interdigitating processes where they are held together. These regions of contact are called the intercalated discs, which cross an entire fiber between two cells
transverse regions of the steplike intercalated disc have abundant __________
desmosomes
longitudinal regions of the discs contain many physiologically important ________ ___________
gap junctions
Transverse regions of the disc have many desmosomes and adherent junctions called ________ __________
fascia adherentes
the heart is composed of what 3 main things ?
endocardium, myocardium and purkinji fibres
what does the endocardium consist of?
consists of the endothelium, a thin layer of connective tissue with smooth muscle cells, and a layer of variable thickness lacking smooth muscle called the subendocardial layer.
The atrial granules contain the precursor of a polypeptide hormone called ______ -_______ -_____
atrial natriuretic factor (ANF)
what does ANF do?
targets cells of the kidneys to bring about sodium and water loss
what is smooth muscle specialzed for and what is it controlled by?
specialized for slow steady contraction and controlled by involuntary mechanisms
_______ __________ associated with the basal laminae of smooth muscle cells help hold the cells together as a functional unit during the slow, rhythmic contractions of this tissue
Reticulin fibres
what are dense bodies?
attachment points for intermediate filaments and thin filaments. Associated with adherens junctions in sarcolemma for transmitting tension between neighbouring cells.
what is the function of caveolae?
regulate release of ca from sarcoplasmic reticulum
what are gap junctions?
electrical coupling of cells , form a syncytium
where is smooth muscle located ?
- Viseral organs (digestive tract, urinary tract (bladder).
- Respiratory airways (spincters control air flow)
- Circulatory system (blood vessel walls, spincters) control blood flow.
smooth muscle isnt voluntary, why?
lack MEPs
what are 3 areas that smooth muscle controls?
- Nervous: autonomic nervous system, sympathetic and parasympathetic.
- Hormonal: Adenaline/epinephrine
- Physiological conditions : stretch, or local oxygen levels.
describe cardiac muscle
Striated muscle, interwoven network of electrically coupled cells (syncytium). Myogenic and autorhythmic. Highly aerobic.
describe smooth muscle
- Non-striated, small fusiform cells which lack T-tubule system and organization of myofilaments. Dense bodies function like Z-disks as well as points for cell to cell contact.
- Can synthesize ECM.
- Found in Visceral organs, respiratory tract and blood vessels.
