Flashcards in Anatomy and physiology ch. 7 The muscular system Deck (61):
also known as striated muscle,
it has 4 major characteristics: contractility, excitability, extensibility, and elasticity
connective tissue sheath that contains the muscle groups
various muscle bundles inside of the epimysium
connective tissue that binds muscle fibers together to make a muscle fasciculi
surrounds individual muscle fibers inside of the muscle fasciculi
the cell membrane of the muscle fiber
also known as T tubules, these go from the surface of the muscle cell and past the sarcolemma (cell membrane)
the T tubules go into this, and this is the place where there is a high concentration of CA2+, which is needed for muscle contraction.
the cytoplasm of the muscle cell
threadlike structures that extend from one end of the fiber to the other. composed of 2 parts, the actin myofilaments, and myosin. these function together to make the muscle contract.
one unit of contracting cells, located between z disks. the smallest unit that can contract by itself.
also known as thin filaments, these are made up of 3 parts. Actin, Troponin, and Tropomyosin
the part that the myosin heads connect to
these have binding sites for CA2+
these block the myosin myofilaments (thick filaments) from joining to the actin molecules. they are moved by CA2+ (found in troponin)
also known as thick filaments, they look like gold clubs, and the head of these attach to the actin when the tropomyosin is moved out of the way.
the ends of a sarcomere, these are protein fibers that separate sarcomeres by providing an attachment for the actin.
consists of only actin myofilaments, has a z disk usually in the middle of it
the area between I disks that looks dark that contains both actin myofilaments and myosin myofilaments. the center of this is the H zone and the M line, which are light
the center of the A band which only contains myosin myofilaments (this is the part that gives so the muscle can contract)
where the myosin myofilaments are anchored to. this is the center of the sarcomere
resting membrane potential
the charge difference across a cell membrane
nerve cells that stimulate muscles to contract. they generate action potentials that travel to skeletal muscle fibers
the synapse between a motor neuron and the muscle cell it is stimulating
refers to the neuron and the skeletal muscle fiber that it controls as a whole
an enlarged axon terminal
the space between the presynaptic terminal and the postsynaptic membrane
the muscle fiber membrane that receives the signal
vesicles that contain acetylcholine which move from the presynaptic terminal to the postsynaptic membrane
resting membrane potential
when the inside of the cell membrane has a more negative charge than the outside of the cell
when the NA+ moves inside of the cell making the inside of the cell positive compared to the outside of the cell
going from the positive back to the resting membrane potential
makes a cell membrane more negative than it was at the resting membrane potential
sliding filament model
1. action potential goes to open CA2+ channels in presynaptic terminals
2. CA2+ causes release of ACh into synaptic cleft
3. Ach binds to receptor sites on postsynaptic membrane, and open NA+ channels, and NA+ rushes in
4. NA+ causes the T tubules and the sarcolemma to release their stored CA2+
5.CA2+ goes to troponin
6. the attachment causes tropomyosin to move out the way of the actin
7. myosin attaches to actin (cross-bridge)
8. P is released and the myosin heads bend
9. the bending make actin slide over the myosin (power stroke)
10.acetylcholinesterase breaks down ACh, NA+ channels close, causing the muscle to stop contracting.
weakest stimulus needed to produce a response
rapid contraction and relaxation of a muscle
when the frequency of stimulation is so fast that no relaxation occurs
the amount of tension in the muscle increases (weight increases)
the amount of repititions increase
constant amount of tension of a long period of time
slow twitch fibers
uses aerobic respiration
fast twitch fibers
uses energy from glycogen
non movable end of a muscle
movable end of a muscle
the middle of a muscle
the muscle that is responsible for the majority of the movement i.e the bicep for flexion of the arm
muscles that work together
muscle that opposes another muscle i.e. the tricep to the bicep
naming skeletal muscle
2. origin/ insertion
lag phase (of muscle contraction)
the lag between the stimulus and actual contraction
contraction phase (of muscle contraction)
time during which the muscle contracts
relaxation phase (of muscle contraction)
time during which the muscle relaxes.
increasing the force of the contraction by rapidly stimulating the muscle. this is caused by dumping more calcium in the myofibrils than is actively transported out to the Sarcoplasmic reticulum
more contraction can occur because more motor units are stimulated to contract.
uses O2 and breaks down glucose to make ATP, CO2, and H2O. this occurs in the mitochondria.
does not use O2, instead it uses glucose to make ATP and Lactic acid. this process uses only glucose.
the muscle cells stored energy that can be used fast to make atp
occurs when the muscle uses ATP faster than it produces it, and lactic acid builds up faster than it is removed
when a muscle cannot contract or relax because there is too little ATP to bind to myosin myofilaments