anatomy exam muscles
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what are the 3 types of muscles?
characteristics of each muscle type
- smooth - nonstriated & involuntary
- cardiac - striated & involuntary
- skeletal - striated & voluntary
what are A Bands?
The Dark bands in thick and thin filaments, that contain the entire myosin molecule and overlapping portion of the actin
what is I Band
the light band (in the organization of thick and thin filaments), contains thin filament but not thick filament
- the region where the motor neuron comes into close proximity to the muscle fiber
- junction is between the muscle and the nerve
what is a motor unit?
- 1 nerve hooked up to many fibers
- consists of a single motor neuron and the muscle fibers it controls
- controls only a few fibers in entire muscle
- a fiber contracts completely or not at all
- when muscle is stimulated all of the fibers under its control will contract
- A wasting of tissue
- reduction of muscle size
- caused by lack of stimulation (exercise)
- increase in muscle size
- (not an increase in muscles fibers)
- results from repetitive stimulation
- myofibrils and myofilaments increase in number which makes muscle increase in size
when do muscle contractions begin?
when a motor neuron impulse stimulates a muscle fiber
what is in the middle of an I Band and what makes it special
- the Z Disc
- protein structure
- serves for the attachment site for one end of the thin filament
what is a sarcomere?
- functional contractile unit in skeletal muscle fiber
- the area between 2 adjacent Z Discs
two main structure that are unique to muscle fiber
- Transverse tubules (T-Tubules)
- Terminal cisternae
what attaches muscle to bone
the point of attachment that does not move is called
the point of attachment that moves is called
each muscle is comprised of
muscles fibers are organized into bundles called
muscle fibers contain
myofibrils are composed of ..
myofilaments are mainly composed of
actin and myosin
the order of skeletal muscle structural organization is
- Muscle Fiber
- Actin and Myosin
skeletal muscles have _____ nucleus.
more than 1, they start as many cells that merge together
functions of skeletal muscle
- maintenance of posture
- temperature regulation
- storage and movement of materials (close an opening/gatekeeper)
what are the properties of a muscle?
how many skeletal muscles
what is a tendon?
- at the end of each muscle all of the connective tissue merge to form tendon
- it is cord like and attaches muscle to bone
- 11nm in diameter
- composed of bundled molecules of myosin
what causes the skeletal muscle to be striated?
the organization of thick and thin filaments
- Prime mover
- produces a specific movement when it contracts
a muscle whose action opposes that of the agonist
where are smooth muscles found
walls of the viscera and blood vessels
a muscle that assists the agonist or prime mover
what shape is the smooth muscle cells
- widest in the middle tapered on each end
the smooth muscle has ____ nucleus
how many nucluei does cardiac muscles have
1 or 2
what shape does the cardiac muscle fibers make
y shaped branches
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