Muscular System Flashcards
What are the basic functions of muscle?
- Voluntary body movement
- Stability of support
- Movement of blood, food, urine
- Control of body openings and passages
What are the 4 properties of muscle tissue and why are they important?
- Excitability - change electrical state
- Contractility - to shorten in length
- Extensibility - to stretch in length
- Elasticity - to return to original shape
What is action potential?
The change in voltage of a cell membrane in response to a stimulus that allows it to do something
What does a relaxed muscles have?
Resting membrane potential
List the layers of connective tissue around a muscle from deep to superficial
- Endomysium - loose CT covering that surrounds each muscle fiber
- Perimysium - CT covering that bundles skeletal muscle fibers into fasicles
- Epimysium - Outer CT layer that surrounds skeletal muscle
- Fascia - dense CT layer that covers and separates groups of muscles
At least how many attachment sites does a muscle have?
Two: origin and insertion
Origin
Anchoring end of a muscle, usually proximal-most. Doesn’t move, pulls muscle toward it.
Where do muscles pull toward?
The origin
Belly (of a muscle)
Midsection, central bulky body of muscle that contracts
Insertion
Opposite end of origin, the end that pulls
Tendon
Dense cord-like CT structure that anchors muscle to a bone
Aponeurosis
A sheet of CT that anchors muscles to each other or to bone
What is true about muscles that span a joint?
The origin is on one side and the insertion is on the other
Prime Mover (Agonist)
Produces the most force during a joint action
Synergist
Adds force to a movement with the prime mover
Antagonist
Opposes or reverse motion of the prime mover
Fixator
Synergist that immobilizes bone at muscle’s origin
List the criteria for naming a muscle
Associated bone or body region
Shape
Muscle action
Relative size
Number of origina
Direction of muscle fibers
Location of origin or insertion
Sacrolemma
Plasma membrane of muscle cell
Sarcoplasm
Cytoplasm of the muscle cell
glycogen storage form of glucose
myoglobin protein to store oxygen
Myofibrilis
Long cylindrical strands of connective proteins
Sarcoplasmic reticulum
A smooth ER that stores Ca ions
T-tubules
Inward projections of sarcolemma that tunnel into a cell, carries the electrical signal from the neuromuscular junction to sarcolemma, causing release of Ca from sarcoplasmic reticulum
Terminal Cisternae
Enlarges areas of SR around the T-tubules
Triad
One T-tubule bordered by two terminal cisternae
Myosin
Protein if a thick filament, grabs actin to shorten sarcolemma and contract the muscle
Actin
Protein of thin filament that contains binding sites for myosin
Troponin
Regulatory protein that binds actin, tropomyosin and calcium
Tropomyosin
Regulatory protein that covers myosin-binding sites on actin
What are the contractile proteins that make sarcomere?
z-disc anchors thin filaments at the ends of the sarcomere
thick filament the center
thin filamenrs attach at z-disc and extend toward the center
Sarcomere
Longitudinally repeating contractile units of skeletal muscle
Motor Unit
A motor neuron and the group of muscle fibers that it innervates
Somatic motor neurons
Control skeletal muscular contractions
What does a muscle need to contract?
A signal
Neurotransmitter
A chemical released by a neuron to control target cells
What is the neurotransmitter that stimulates a muscle contraction?
Acetylcholine (ACh)
What breaks down ACh?
A-cetyl-cho-lin-este-rase
What is the relationship between motor unit size and muscle force?
Size matters: it determines the amount of control. It is possible to recruit more units for stronger muscle contractions
