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Histo-S1-Mini Two-Muscle Tissue-Aidi Yin
Muscle Tissue lecture
41
Histology
Professional
10/17/2010

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Term
sarcolemma
Definition
Muscle fiber cell membrane
Term
Sarcoplasmic reticulum
Definition
Smooth endoplasmic reticulum of the muscle fiber
Term
All muscle is derived from mesoderm except which one?
Definition
Dilator pupillae muscle
Term
Cross-striations
Definition
Alteration of light and dark bands; Skeletal and cardiac muscle has this
Term
Type 1
Definition
Red skeletal muscle;   slow but repetitive, not easily fatigued. Smallest diameter. Rich in myoglobin so has a lot of iron in it. Largest density of mitochondria; gets energy from oxidative phosphorylation of ATP.
Term
Type IIB
Definition
White skeletal muscle;     fast but easily fatigued, largest diameter, poor myoglobin, least density of mitochondria; gets energy from glycolysis (phosphorylase and ATPase); e.g. for energy at digits, eyeball muscle, for precise movements
Term
Type IIA
Definition
Intermediate
Term
epimysium
Definition
covers entire muscle
Term
perimysium
Definition
covers a muscle bundle/fascicle
Term
endomysium
Definition
covers each muscle fiber; can find capillaries and loose CT here
Term
muscle
Definition
made by bundle of fascicle; covered by epimysium
Term
fasciculus
Definition
made of muscle fibers; covered by perimysium
Term
muscle fiber
Definition
muscle cell, contains myofibrils, covered by endomysium
Term
myofibril
Definition
composed of bundles of myofilaments
Term
myofilaments
Definition
contains contractile proteins (actin and myosin), visible only under EM
Term
Sarcomere
Definition

functional unit of each myofibril; composed of actin, myosin, and accessory proteins; repeating structure between two Z lines

 

 

[image]

Term
desmin
Definition
is the in the cytoplasm between each myofibril; joins Z lines of adjacent myofibrils at the same level together which makes A bands, I bands, and Z lines perfectly aligned however not perfectly straight but jerky.
Term
M band
Definition
is the center of the sarcomere and the center of A band and H band; it's the structure where the thick filaments are attached; has proteins that attach on the thick filaments and space/align them out properly
Term
I band
Definition
where the only thin filaments (actin) is
Term
A band
Definition
where the thin and thick filaments are both are, but is equivalent to the longitudinal length of a thick filament
Term
H band
Definition
is the lighter zone, where you only have thick filaments
Term
Thin filament
Definition
F actin, polymer formed from globular actin molecules (G-actin)
Term
Thick filament
Definition
200-300 myosin II molecule aggregates in a parallel but staggered array, heads pointing away from the center of the sarcomere
Term
Tropomyosin
Definition

are controlled by tropinin T; they cover the myosin binding site;  

 

Term
thin filament
Definition
they have chain of G actin that line up and polymerize and have two strings of G (globular) actin
Term
Troponin
Definition

has three subunits:

 

1.) Troponin C - Ca++ binding site

2.) Tropnin T - Tropomyosin binding site

3.) Troponin I - binds to actin; inhibits actin-myosin interaction

 

 

Term
Myosin II molecule or filament
Definition

composed of two heavy chains and two pairs of light chains; the shaft of two heavy chains are wrapped aorund each other; The two pairs of light chains associate with the hats of the heavy chains

 

 

Term
C-protein
Definition
is an accessory protein; is a myosin binding protein; helps thick filaments attach at M-line
Term
myomesin
Definition
is an accessory protein and a myosin-binding protein; helps thick filaments attach at M-line
Term
alpha-actinin
Definition
helps to make Z-line; is an actin-binding protein; helps actin bind to Z-line
Term
nebulin
Definition
accessory protein that helps attach a thin filament with Z-line
Term
titin
Definition
an accessory protein that attaches at z-line and attaches at middle of thick filament; attaches thick filament to z-line to prevent excessive stretching of sarcomere
Term
accessory protein
Definition
maintains precise alignment of thin and thick filaments; helps with spacing, attachment and alignment
Term
trypsin
Definition
cleaves between the hinge of the myosin II molecule which sticks upward and away from the rest of the sarcomere and the rest of that myosin molecule that stays with the sarcomere and filament
Term
papain
Definition
cut off hat from rest of hinge molecule of that myosin II molecule that sticks up and away from the sarcomere; separates hinge into S1 and S2 portions
Term
creatine kinase
Definition
present at M-line and helps provide the supply of ATP and ADP during contraction
Term
Dystrophin
Definition
binds to actin and aids in binding the myofibrils to the cytoplasmic aspect of the sarcolemma (muscle fiber cell membrane), then to laminin in the external lamina; find in inner surface of sarcolemma
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