(P) Lec 3.2: Muscular Tissue Flashcards
PPT-based
part of the cytoplasm
sarcoplasm
part of the cell membrane and external lamina
sarcolemma
part of the ribosomes
sarcosomes
part of the the smooth ER
Sarcoplasmic reticulum
All muscle cells are derived from
Mesoderm
cross-striations and cylindrical/elongated with blunt ends muscle cell with diameters of 10-100 μm.
Skeletal Muscle
T or F. The cardiac muscle is referred to as “fiber”
F (skeletal)
Large numbers of parallel skeletal muscle fibers are grouped into?
fascicles or bundles—arrangement
The nuclei (of skeletal muscle) are found at the periphery or eccentric under the?
sarcolemma (cell membrane surrounding a skeletal muscle fiber)
contraction is quick, forceful, and usually under voluntary control.
SKELETAL
external sheath of dense connective tissue that encloses the entire muscle
epimysium
A thin septa of dense connective tissue that immediately surrounds each bundle of muscle fibers termed a fascicle
Perimysium
Delicate layer of loose connective tissue (fibers and scattered fibroblasts) that surrounds the external lamina of individual muscle fibers; INSIDE THE FASCICLE
endomysium
the functional and structural unit of contraction in skeletal muscle; extends from Z disc to Z disc
Sarcomere
dark bands are called the
A band or anisotrophic bands
they are doubly refractile or birefringent under polarized light
A band or dark banks
they do not alter polarized light
light bands or I bands
center of the A band is a pale zone termed
H band
center of this H band is a narrow dark line, known as the
M band
depolarization of sarcoplasmic reticulum membrane, which results in the release of
Ca+++ ions
The depolarization of sarcoplasmic reticulum membrane is initiated at a?
specialized myoneuronal junction
To provide for a uniform contraction, skeletal muscles posses a system of?
transverse (T) tubules (fingerlike invaginations of the sarcolemma that form a complex anatomosing network of tubules that encircle both A-I junctions of each sarcomere in every myofibril)
end-to-end repetitive arrangement of sarcomeres
myofibrils
2 types of filaments of skeletal
myosin filaments and actin
principal constituent of the A band
thicker myosin filaments
Bound to opposite side of each T-tubule processes are expanded
terminal cisternae of the sarcoplasmic reticulum
This specialized complex, consisting of Sr-T tubule – SR components, is known as the?
“triad of skeletal muscle”.
a 40-nm-long coil of two polypeptide chains located in the groove between the two twisted actin strands
tropomyosin
a complex of three subunits: TnT, which attaches to tropomyosin; TnC, which binds Ca2+; and TnI, which regulates the actin-myosin interaction
Troponin
skeletal muscle: mechanism of contraction is due to
sliding or overlapping of the myofilaments
Cross striated, cylindrical or elongated, OFTEN branching muscle fibers
Cardiac Muscle
Contraction is involuntary,
vigorous, and rhythmic.
Cardiac muscle
ALSO encloses the cardiac muscle
connective tissue sheath
what main junction is present in the intercalated discs?
zonula adherens
Three main junctional specializations within the discs
- Fascia adherens (Fascia junctions) & Desmosomes (Maculae adherens)
- Gap junctions
T or F. The contractile substance in the same interdigiting relationship as that of skeletal muscle.
T
T or F. The cardiac muscle’s sarcoplasmic reticulum is well organized compared to skeletal muscle fibers.
F (not well organized)
Lack striations and contraction is relatively slow
Smooth or Visceral
slow, steady contraction under the influence of autonomic nerves and various hormones
Smooth or visceral
identify muscle tissue: Myofilaments criss-cross obliquely through the cell, forming a latticework network
Smooth
T or F. All muscle tissue forms a sarcomere.
F (smooth lang walang sarcomere)
T or F. The contractile unit is the smooth muscle cell itself.
T
T or F. The calcium regulating sarcoplasmic reticulum is greatly reduced in skeletal muscle tissue.
F (smooth)
T or F. Visceral tissue is not regularly arranged as that of striated muscles
T
