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What are the 3 basic types of muscle?
How are muscle cells shaped?
What causes contraction of muscles?
The movement of microfilaments.
What are the characteristic of skeletal muscle?
1. Attached by tendons to bones
2. Have more than one nucleus, or are multinucleate
3. Striated - visible banding
5. Surrounded and bundled by connective tissue
What are the 2 types of tissue wrapping of skeletal muscle fibers or cells?
1. Endomysium - around single muscle fiber
2. Perimysium - around fascicles, or bundles of muscle fibers
What covers the entire skeletal muscle?
Where is the facia located?
On the outside of the Epimysium of a skeletal muscle.
What are the 2 types of Epimysium?
1. Tendons - cord like
2. Aponeuroses - sheet like
Where are muscles attached?
3. Connective tissue coverings
Characteristic of Smooth Muscle:
1. No striations
2. Spindle shaped cells
3. Single Nucleus
5. Found in the walls of hollow organs
Characteristics of Cardiac Muscle
1. Has striations
2. Usually has a single nucleus
3. Intercalated Discs
What are the functions of muscles?
1. Produce movement
2. Maintain posture
3. Stabilize joints
4. Generate heat
What is the sarcolemma?
Specialized plasma membrane of skeletal muscle.
What is the Sarcoplasmic Reticulum?
Specialized smooth endoplasmic reticulum found in skeletal muscle.
What are Myofibrils?
Bundles of Myofilaments.
What are the 2 types of Myofibrils?
1. I Bands - light bands
2. A Bands - dark bands
What is a sarcomere?
Contractile unit of a muscle fiber.
How are sarcomeres organized?
1. Thick filaments
2. Thin filaments
What are thick filaments?
Filiaments that are composed of the protien Myosin. They have "heads."
What are thin filaments?
Filaments that are composed of the protien Actin.
What does the sarcoplasmic reticulum do?
What is irritability?
Ability to receive and respond to a stimulus.
What is contractility?
Ability to shorten when an adequate stimulus is received.
In order of a muscle to contact, what must happen?
The muscle must be stimulated by a nerve.
What is a neuromuscular junction?
The association site of a nerve and muscle.
What is a synaptic cleft?
Gap between nerve and muscle.
What is interstial fluid?
Fluid that fills the synaptic cleft.
What is a neurotransmitter?
Chemical released by a nerve upon the arrival of a nerve impulse.
What is acetylcholine?
The neurotransmitter of a skeletal muscle.
How do neurotransmitters in skeletal muscles work?
They attach to receptors on the Sarcolemma.
What happens when the neurotransmitter reaches the Sarcolemma?
Sodium rushing into the cell causes an action potential.
What are the steps in Sliding Filament Theory of Muscle Contraction
1. Myosin heads attach to binding sites on thin filaments.
2. Myosin heads then bind to the next site of the thin filament.
3. This continued action causes a sliding of the myosin along the actin.
4. Because of this sliding, the muscle is shortened (contracted)
What is the energy for muscle contraction?
How long can muscles contract?
Until they run out of energy or ATP.
How much ATP does a muscle store?
4 - 6 seconds worth.
After ATP is depleted, what is left?
How is ATP regenerated?
CP transfers energy to ADP, which produces more ATP.
What happens when a muscle is fatigued?
It is unable to contract.
What is the most common reason of muscle fatigue?
Oxygen debt, or lack of oxygen to the muscle.
What 2 points are muscles attached at?
Origin - attachment to an immovable bone
Insertion - attachment of a movable bone
What are the types of ordinary body movement?
- 1. Flexion
- 2. Extension
- 3. Rotation
- 4. Abduction
- 5. Adduction
What is flexion?
A joint moving.
Example: Bending the elbow.
What is extension?
Extending a body part.
What is rotation?
The ability to rotate a body part.
What is abduction?
The movement of a body part away from the midline of the body.
What is adduction?
The movement of a body part towards the midline of the body.
What is a prime mover?
Muscle with the major responsibility for a certain movement.
What is an Antagonist?
Muscle that opposes or reverses a prime mover.
What is a synergist?
Muscle that aids a prime mover in movement and helps prevent rotation.
What is a fixator?
Stabilizes a prime mover.
How are skeletal muscles named?
- Direction of fibers
- Number of origins
- Origin and insertion
- Relative use
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