Muscle PDF Flashcards
Forms the main bulk/flesh of the human body
MUSCULAR TISSUES
Function of muscular tissue
contractility
TYPES OF MUSCLES
- Striated
– Skeletal muscle (voluntary)
– Cardiac muscle (involuntary) - Smooth muscle (involuntary)
- Contractile filaments (actin and myosin)
Bundles of very long, cylindrical, multinucleated cells that show cross-striations.
SKELETAL MUSCLE [VOLUNTRAY]
Muscles attach to the skeleton
SKELETAL MUSCLE [VOLUNTRAY]
striated, voluntary
SKELETAL MUSCLE [VOLUNTRAY]
long, broad tubular muscle fiber
SKELETAL MUSCLE [VOLUNTRAY]
contains cylindrical filaments called myofibril (smaller unit of muscle fiber)
SKELETAL MUSCLE [VOLUNTRAY]
CONNECTIVE TISSUE INVESTMENTS
EPIMYSIUM
PERIMYSIUM
ENDOMYSIUM
surrounds entire muscle
EPIMYSIUM
surrounds muscle bundles or fascicles (smaller unit of muscle bundles)
PERIMYSIUM
Encloses the muscle fiber
ENDOMYSIUM
Composes the muscle fascicle
ENDOMYSIUM
surrounds individual muscle cells
ENDOMYSIUM
Reticular fibers and external lamina
ENDOMYSIUM
Long, cylindrical, multinucleate
SKELETAL MUSCLE CELLS
Sarcoplasm, sarcolemma with T (transverse) tubules
SKELETAL MUSCLE CELLS
long cylindrical filament bundles
MYOFIBRILS
Parallel to the long axis of the fiber
MYOFIBRILS
Thick filaments
myosin
Thin filaments
actin
Visible Dark A bands, light I(isotropic) bands (bisected by Z disks)
MYOFIBRILS
DESMIN (with plectin) glues Z disks together
MYOFIBRILS
CROSS-STRIATIONS
A-bands
I-bands
H-bands
M lines
Z disks (lines)
Anisotropic; stain dark; thin and thick filaments
A-bands
Isotropic; light stain; thin filaments
I-bands
Light regions transecting A bands; thick filaments
H-bands
Narrow dark regions at center of H bands; cross-bridges
M lines
Dense regions bisecting I-band
Z disks (lines)
extends Z to Z disc
SARCOMERE
Functional unit of contraction (fibril)
SARCOMERE
Dilated terminal cisternae that encircle myofibrils at the junction of each A and I band
SACROPLASMIC RETICULUM
Regulates muscle contraction by calcium sequestration (relax) and release (contract)
SACROPLASMIC RETICULUM
Central T tubule flanked by 2 terminal cisternae of SR
TRIADS
Help provide uniform contraction
TRIADS
THIN FILAMENTS [ACTIN]
F-ACTIN
TROPOMYSIN
TROPONIN
double helix arrangement
F-ACTIN
has an active site for interacting with myosin
F-ACTIN
In the grooves of the F-actin helix
TROPOMYSIN
TROPONIN
TnT
Tnc
TnI
bind to tropomyosin
TnT
4 binding sites for calcium
Tnc
binds to actin, inhibiting myosin-actin interaction
TnI
2 identical heavy chains and 2 pairs of light chains
Myosin II
Double-headed golf club
Myosin II
Globular heads (S1 fragments) have ATPase activity but require interaction with actin to release ADP and Pi.
Myosin II
During contraction, thick and thin filaments do not shorten but increase their overlap
HUXLEY’S SLIDING-FILAMENT MODEL
Thin filaments slide past thick filaments and penetrate more deeply into the A band, which remains constant in length
HUXLEY’S SLIDING-FILAMENT MODEL
I and H bands shorten as Z disks are drawn closer together
HUXLEY’S SLIDING-FILAMENT MODEL