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Muscle Histology and Physiology
Muscle Histology and Physiology
19
Anatomy
12th Grade
11/06/2012

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Term
Four major functional characteristics of muscle
Definition
Extensibility: stretched out
Elasticity: recoil after extended
Contractility: shorten forcefully
Excitability: stimulated by nerves and hormones
Term
Three functions of muscle
Definition
Posture
Heat production
Movement
Term
Three types of muscle
Definition
Skeletal
Smooth
Cardiac
Term
Skeletal
Definition
Striated
Voluntary
Multinucleate
Term
Cardiac
Definition
Only in heart
Striated
Single nucleus
Involuntary
Term
Smooth
Definition
Non striated
involuntary
Single nucleus
Term
Skeletal muscle structures from small to large
Definition
Microfilaments of actin or myosin

Sarcolemma, sarcoplasmic reticulum, myofibrils

Muscle fiber cell surrounded by endomysium

Fascicle with perimysium

Muscle wrapped in epimysium
Term
Sarcomeres
Definition
Repeating units of myofibrils
Term
5-step cycle of a sarcomere contraction
Definition
1. Active sites on the actin myofilaments are not exposed, so the heads of the myosin myofilaments are ready.

2. Ca++ bind to troponin which makes the proteins in the actin myofilaments rearrange to expose the active sites where the myosin heads can bind. Phosphate is the ejected.

3. Power Stroke: The heads bend which pull the actin myofilaments in the direction of the bend. ADP is ejected.

4. ATP molecules bind to the heads, causing them to release the active sites. The actin myofilament has moved.

5. Return stroke: ATP molecules break down into ADP and P which remain bound to the mysoin heads which release energy for the heads to spring back again.
Term
Troponin and Tropomyosin
Definition
Proteins in the actin myofilament. Tropomyosin wraps around the actin molecules while the troponin lie across the troponin.
Term
The myosin filament is formed from...
Definition
myosin
Term
The actin filament is formed from...
Definition
actin
Term
Which filament is thicker and darker?
Definition
Myosin filament
Term
which filament "surrounds" the other?
Definition
Actin filament
Term
There are certain active sites on the ____ and the combination of a _____ _____ with the active site of an _____ ________ is called a cross bridge.
Definition
Actin, myosin head, actin myofilament
Term
A bands
Definition
Myosin myofilament
Term
I bands
Definition
Actin myofilament (no myosin!)
Term
Z disk
Definition
"Boundary"of sarcomere that serve as a place to which the actin myofilaments can be anchored.
Term
H zone
Definition
Area in between the ends of the actin myofilaments
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