Ch. 13 Physiology
Terms
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- Skeletal muscle cells
- muscle cells must be stimulated by somatic motor nervous system neurons before they can contract.
- Skeletal muscle structure
-
Connective tissue tendons connect the contreactile part of a muscle (body or belly) to bones.
A muscle contains many groupings of hundreds of cells, each group called a fascicle.
The connective tissue that surrounds each fascicle conbine to form the tendons.
Perimysium - surrounds each fascicle
Endomysium - surrounds each cell
Endomysia - are connected to the perimysia - Connective tissue
- __________ _______ tendons connect the contreactile part of a muscle (body or belly) to bones.
- fascicle
- A muscle contains many groupings of hundreds of cells, each group called a _________.
- tendons
- The connective tissue that surrounds each fascicle conbine to form the _______.
- Perimysium
- surrounds each fascicle
- Endomysia
- are connected to the perimysia
- Muscle fibers (cells)
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Fibers
Fibrils
Filaments
Long cells that run the length of the muscle - Endomysium
- covered w/ conn. tissue that is continuous w/fibers from the fascicles.
- myofibrils
- All __________ shorten in response to stimuli to the muscle cell. ( Takes use to the "All or none" law)
- sarcoplasmic reticulum (S.R.)
- Surrounding the myofibrils is the __________ _________ is connected to the cell's membrane by the T-tubules.
- Sarcoplasmic reticulum
- acts to store and release Ca++ into the cytosol.
- Mitochondria
- The S.R. surrounding the myofibrils, is also surrounded by ____________, which is available to produce energy.
- Molecular structure
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Contractile filaments (myofilaments) within the myofibrils are arranged in a exact pattern producing a banded appearance.
2 types of contractile filaments in each myofibril (thin and thick).
Filaments are arranged into repeating segments called sarcomeres (functional contractile units in a muscle cell). - Contractile filaments (myofilaments)
- __________ __________ within the myofibrils are arranged in a exact pattern producing a banded appearance.
- Thin filaments
- Ca++ binding to troponin moves the tropomysin.
- Tropomysin
- _________ acts to control the interaction of thick and thin filaments. It acts to block the G actin binding sites.
- Tropinin
- ________ acts to move tropomyosin awayfrom the binding site when a muscle cell is stimulated.
- Thick filaments
- Found positioned in the center of each sarcomere.
- crossbridge
- At each end has a protruding portion called a head or ___________.
- Excitation-contraction coupling
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The action of releasing a neurotransmitter at a muscle cell which INDIRECTLY leads to the contraction of that cell.
(calcium makes muscle contraction). - Interaction of thick & thin filaments
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the actual shortening of sarcomeres occurs at the thin & thick filaments
When Ca++ combines with troponin, and move tropomysin in actin binding sites for myosin are now exposed.
Myosin heads can now interact w/ actin. - Muscle fiber contraction
-
a repeating system
When stimuli to muscle cell are removed:
a. Ca++ is actively transported into S.R. by Ca-ATPase, decreasing Ca++ binding to troponin.
b. Tropomyosin moves back over actin binding sites stopping myosin-actin interaction & sarcomere shortening - sarcomeres
- Each myofibril is composed of thin and thick filaments arranged in ___________.
- conn. tissue
- Myofibrils shortening shortens the muscle cell which pulls on __________ _______ w/in the cell.
- tendon
- These conn. tissues exerts force on the _______ which pulls on the bone to be moved.