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Muscle physiology
| Question | Answer |
|---|---|
| what is the general source of stimulation? | a neuron |
| what is the name of the junction between axon terminal and motor end plate? | neuromuscular junction |
| what is the axon terminal? | the end of an axon |
| what is a synaptic vessicle? | vessicles within the axon terminal that contain the neurotransmitter ACh which gets the message from neuron to muscle cell |
| what is the neurotransmitter associated with the snyaptic vessicles? | acetocholine |
| what is the synaptic cleft? | the space between the axon terminal and motor end plate |
| what is the motor end plate? | the plate that has receptors for acetocholine on it |
| what is it called when there is a charge difference? | resting potential |
| on the outside of the cell membrane there is an abunance of..? | Na+ (sodium ions) |
| on the inside of the cell membrance there is an abundance of...? | K+ (potassium ions) |
| what makes the inside of the cell membrane negative? | although there is an abundance of K+ on the inside, there is still more sodium ions on the outside, therefore, there is a difference in the charges |
| only ____ and ____ cells can do something with the resting potential | muscle and nerve |
| all other cells just ____ resting potential | maintain |
| whwhat happens to the sodium and potassium ions when the membrane of a nerve or muscle cell is stimulated? | there is a change in the permeablity in the membrane so sodium ions go to the bottom and potassium ions go to the top |
| the change in permeablitiy of the membrane happens _____ at a time. the outside stimuli causes the first to _____ than first stimulates the second to ______ | one; switch; switch |
| the "switch" during action potential is really what? | depolarization |
| what is action potential? | the self propogating wave of depolarization |
| what is the first step for excitation-contraction coupling? | action potential comes down axon terminal and changes the permeablity of the terminal |
| what is the second step for excitation-contraction coupling? | Ca+ comes from the envronment and makes the synaptic vessicles merge with the terminal so acetocholine can diffuse across the synaptic cleft |
| what is the 3rd step for excitation-contraction coupling? | the acetocholine diffuses across the synaptic celft and attaches to the receptors on the motor end plate |
| what is the 4th step for excitation contraction coupling? | the attachment to the motor end plate allows the action potential to travel along the sarcolemma and once it gets to the t tubles it changes the permeablity in the terminal cisternae and allows them to release Ca+ |
| what is the 5th step for excitation contraction coupling"? | calcium binds to troponin and tropomyosin |
| what is the 6th step for excitation contraction coupling? | cross bridges flip up and connect to actin and cause it to slide toward the H zone |
| what is the 7th step for excitation contraction coupling? | acetylcholinesterase stops contraction |
| ATP comes from? | broken down glucose |
| what do you get when you take away a phosphate from ATP? | ADP |
| the ADP releases | energy and the ability to do work is prsent |
| ATP is stored in | the myosin head |
| a new ATP molecule after cross bridges are flipped... | breaks attachment |
| what is the first step of the cross bridge attachment? | energized myosin head attaches to actin and forms a cross bridge |
| what is the second step of the cross bridge attachement? | the power stroke |
| what is the power stroke? | ADP + P 1 is released and myosin head pivots and bends and pulls on the actin and slides it toward the M line |
| what is the 3rd step of the cross bridge attachment? | ATP attaches to myosin and the link between actin and myosin weakens and myosin head detaches |
| what is the 4th step of the cross bridge attachment? | ATP gets hydrolized to ATP and P1 and then the head returns to its unattached position |
| what is tension? | force buliding up in muscle (inside the muscle) |
| what is load? | what is being moved (outside the muscle) |
| what is isotonic contraction? | when there is no change in tension but a change in length |
| what is isometric contraction? | when there is no change in length but a change in tension |
| the motor unit is the functional unit of..? | the whole muscle |
| what does the motor unit include? | the motor neuron, muscle cell of which the neuron is attached |
| How many axon terminal associations does each cell have? | only 1 |
| How many motor units and axon terminals can an axon have? | many |
| How do we maintain tone? * | by having different motor units work on the same |
| what is a myogram? | picture of electrical activity of the muscle |
| what is a twitch? | when a muscle is stimulated once by a single stimulus that produces a quick jerking movement |
| What is the lag phase in a myogram? | latent period in contraction where the charge is still moving down the sarcolemma, etc |
| what is contraction in a myogram? | building up of muscle tension; the # of myosin & actin bonds begin to increase until it reaches maximum contraction |
| what happens after contraction in a myogram? | period of relaxation |
| different muscles will respond ______ to the same stimulus | differently |
| what is graded muscle response? | tension in the muscle changes gradually |
| contraction strength can change only by: | stimulus frequency and stimulus intensity |
| what is stimulus frequency? | how many times stimulus is applied |
| what is stimulus intensity? | amount of stimulus being applied |
| in low stimulus frequency contraction, the stimulation is: | unfused and incomplete |
| what is wave summation? | build up of stimultion that is greater than the previous stimulation applied because it adds to the previous one before it finishes contraction |
| in wave summation, why is stimulation greater each time it is applied? | because it adds stimulation before the contraction can finish |
| the more rapidly the stimulation is applied, the ._______ the stimulation | greater |
| in high stimulus frequency contraction the stimuation is: | fused tetanus |
| what is the stimulation tetanus in high frequency stimulation? | because the stimulus is applied before the contraction has time to begin to undo itself |
| what causes muscle to fatigue | fused tetanus contraction because the cell cannot respond because of a lack of energy |
| a change in stimulus intensity is generally measured in what? | volts |
| more and more motor units begin to be _____ with increase of intensity | excited |
| what is threshold intensity? | the point at which there is a first response to the buliding intensity of stimulus |
| what is the lowest intensety that will genereate a response from a muscle called? | threshold intensity |
| what is subthreshold intensity? | intensity applied before threshold that is too weak to generate a response |
| what is maximal stimulated intensity? | stimulus intensity beyond which there is an increase in contraction |
| the more and more intensity added after threshold, the more ___ are filled to capactiy | myofibrils |
| why is it when you reach maximal intensity in stimulus intensity, will the contraction not increase? | because all of the motor units have been engaged |
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