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Definition
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a device that gives a graphical representation of spatial position over time in which a spatial axis represents time
Karl Ludwig |
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| instrument for measuring alternating or varying electric current in terms of current and voltage |
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Definition
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| 3 components of a recording channel |
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Definition
1. sensing device
2. processor (with coupler and amplifier)
3. recorder/reproducer |
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| 2 sensing devices of the recording channel |
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Definition
1. electrode
2. transducer |
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type of sensing device that measures electrical events
e.g. EKG |
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Definition
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device that transforms energy from one form to another (mechanical to electric)
e.g. myograph |
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Definition
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component of recording channel that consists of a coupler and an amplifier
e.g. MP35 |
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Definition
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portion of the recording channel that makes a permanent record
e.g. computer hard drive |
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Definition
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Definition
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synchronizing the signal from the sensing device and the deflection on the record
done by putting a known weight on a myograph and adjusting the deflection of the line to read the required amount |
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Definition
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Term
minimum stimulus needed to elicit a physiological response
e.g. 20 mV for an excitable cell |
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Definition
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| electrical shock/jolt from stimulator |
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Definition
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| 3 components of a stimulus |
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Definition
1. intensity
2. frequency
3. duration |
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| strength of stimulus (mV) |
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Definition
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how often during a set period of time a stimulus is given
# stimulations / second (Hz)
e.g. 10 Hz = 10 shocks / sec |
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Definition
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length of time each individual stimulus lasts
each shock lasts 1 ms |
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senses physiological information and sends it to the computer
e.g. electrode |
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Definition
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| type of transducer that converts mechanical energy from muscle contraction into electrical energy |
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Definition
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| component of processor that modifies the electrical signal so that it can be recognized by the remaining components of the recording channel |
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Definition
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| component of processor that boosts the electrical signal so that we can measure it |
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Definition
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| these are used to deliver electrical stimulus to the experimental setup (e.g. muscle) to cause a physiological response (e.g. contraction) |
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Definition
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| functional unit of skeletal muscle |
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Definition
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Term
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Definition
1. motor nerve cell (neuron)
2. neuromuscular junction (NMJ)
3. muscle fiber |
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| cell whose soma lies in the spinal cord and whose axons branch, forming terminals that innervate a finite number of individual muscle fibers |
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Definition
| motor nerve cell (neuron) |
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| structure that connects the terminals of the axon to the muscle fibers |
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Definition
| neuromuscular junction (NMJ) |
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| space that separates the membranes of the terminals of the axon from the muscle |
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Definition
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T/F
Individual motor neurons possess different thresholds |
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Definition
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| The neurons with the lowest thresholds are...(2) |
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Definition
1. smallest in diameter
2. innervate fewest muscle fibers |
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| Type of muscle response in which increasing the STRENGTH of the stimulus will bring more and more neurons into action...eventually all motor units will be activated and the muscle twitch will be at its maxium force. Additional stronger stimuli can be added but there will be no additional effect. |
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Definition
| motor unit summation (multi-unit summation) |
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Term
| When a nerve is stimulated, the impulse generated by the nerve lasts about _____ |
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Definition
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period after a stimulus is given in which a second stimulus will not cause a second impulse to be produced
1-5 ms usually |
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Definition
| absolute refractory period |
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Term
| When a nerve impulse stimulates a skeletal muscle fiber to contract, the contractions lasts for about _____ |
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Definition
| 125 msec (much longer than a nerve IMPULSE) |
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Term
| After the 1-5 ms refractory period, giving a second stimulus will result in a second contraction, and the forces of the two will be added. This is called _______ |
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Definition
| temporal summation (wave summation) |
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Term
| type of muscle response in which the tension generated by the muscle is added over a period of time in which the muscle is not allowed to completely relax (tension added by increasing FREQUENCY) |
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Definition
| temporal summation (wave summation) |
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| when the muscle is in a state of maximum sustained contraction |
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Definition
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| all motor units are firing as rapidly as possible and the maximum tension of the muscle is generated |
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Definition
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structural unit of the muscle cell
composed of contractile proteins, actin (thin filament) and myosin (thick filament)arranged between adjacent membranes called Z-lines |
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Definition
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| filamentous protein composed of double helical chains of globular actin, wrapped by two other proteins called troponin and tropomyosin |
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Definition
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contractile protein that is a thick filament
golf-club shaped heads |
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Definition
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| location at which a myosin head attached to an actin filament |
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Definition
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| 3 components of myofilament |
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Definition
1. myosin
2. actin
3. troponin-tropomyosin complex |
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constitutes the effective contractile elements of the muscle cell
composed of many sarcomeres laying end to end |
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Definition
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| muscle cell membrane that envelopes myofibrils and invaginates deep into the center of the cell |
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Definition
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| invaginations located at the Z-lines of amphibian muscle |
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Definition
| T-tubules (transverse tubules) |
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Term
| structures that release Ca++ to bind to TTC when electrical stimulus reaches T-tubules (and reabsorbs Ca++ when stimulus stops) |
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Definition
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| structure where two lateral sacs and a T-tubule come together in a region of the Z-line |
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Definition
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Definition
| troponin-tropomyosin complex |
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| the stimulation of motor neurons travels through what nerve? |
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Definition
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| Describe the 15-step process of a muscle contraction (and relaxation) beginning with the stimulation generating an AP |
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Definition
1. stimulation --> AP
2. AP --> nerve terminals
3. neurotransmitter (Ach) released at terminal
4. Ach diffuses across NMJ
5. Ach binds to receptor on muscle membrane
6. local depolarization --> AP propogation along sarcolemma
7. impulse -> T-tubules
8. Ca++ released from lateral sacs
9. Ca++ binds to troponin
10. TTC changes shape to expose binding sites on actin filament
11. myosin head forms crossbridge with actin filament
12. myosin head pulls actin inward
13. sarcomere shortens, contracting muscle
14. Ca++ pumped out of sarcomere back into SR (powered by ATP)
15. Ca++ reabsorbed by lateral sacs to relax muscle |
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Term
| Role of Ca++ in muscle contraction (2) |
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Definition
1. activates myosin ATPase
2. binds to troponin component of actin polymer, causing the TTC to change shape, exposing binding sites where myosin can form a crossbridge with the actin filament |
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Term
| enzyme that allows ATP to bind to the active site and be split, releasing energy to end the myosin head out and upward toward the actin filament |
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Definition
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T/F
As long as Ca++ is present in the sarcomere and is bound to troponin, the interaction between actin and myosin will continue and the muscle will continue to contract |
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Definition
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Definition
1. supplies energy that allows muscle to contract
2. used to initiate relaxation by powering the Ca++ pump in the SR that clears the sarcomere of Ca++ |
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| How does ATP supply energy to allow a muscle to contract? |
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Definition
| causes the myosin head to deform, stretching it back and out toward the Z-line |
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Term
| How does lowering the temperature of a muscle affect contraction and relaxation? |
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Definition
Slows function of three important enzymes:
1. Myosin ATPase (slow contraction)
2. Ca++ ATPase (slow relaxation)
3. AchE (increase contraction?) |
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| enzyme involved in pumping Ca++ out of the sarcomere back into the SR to be reabsorbed by the lateral sacs |
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Definition
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| How does fatigue affect muscle contraction and relaxation? |
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Definition
Excessive contraction quickly depletes the finite energy stored in a muscle
Force of contraction becomes weaker, relaxation becomes longer.
ATP cannot be generated as quickly as it is being used (slows glycolysis) |
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| act of myosin head binding to actin filament at cross-bridge and pulling it inward to shorten sarcomere |
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Definition
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| What is AchE and how does it affect muscle activity? |
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Definition
Acetylcholinesterase
breaks down Ach
no AchE --> lots Ach --> increased contraction period |
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| nerve that causes a skeletal muscle to contract |
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Definition
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| transcient and recoverable decline in muscle force and/or power with repeated or continuous muscle contractions |
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Definition
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| 3 physiological factors hypothesized to be the INITIAL cause of fatigue |
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Definition
1. nerve itself fatigued from overstimulation --> no longer able to produce APs
2. NT depleted --> AP cannot be transmitted across synapse to muscle
3. muscle itself fatigued (4 factors) |
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| 4 factors that could result in muscle fatigue being the initial cause of fatigue |
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Definition
1. creatine phosphate degradation
2. altered pH (due to lactic acid buildip)
3. buildup of P from ATP breakdown
4. deleterious effects on Ca++ release and uptake |
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Term
| channels that are large proteins embedded in the lipid bilayer that make us the cell's plasma membrane |
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Definition
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| the ______ of the lipids surrounding the Na+ channels facilitates the shape changes by allowing the proteins to move somewhat freely within the membrane |
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Definition
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| What is lidocaine and how does it affect muscle activity? |
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Definition
anesthetic
stabilizes lipid bilayer, causing it to be rigid and inflexible, making it harder for the ion channels (proteins) to change shape, making it difficult for the nerves to generates APs |
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Term
| receptors associated with Na+ channel at the muscle cell membrane that respond to Ach |
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Definition
| nicotinic type 2 receptors (N2 receptors) |
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Term
| What is D-tubocurare (dtc, curare) and how does it affect muscle activity? |
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Definition
| neurotoxin that blocks Ach neurotransmitter from binding to N2 receptor, preventing the Na+ channel from opening --> hinders AP |
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| Mechanical stimulation: will pinching a nerve more distal than proximal result in a bigger or smaller contraction? Why? |
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Definition
| A distal pinch will have a bigger contraction because more motor units need to be involved for the stimulus to travel the long distance to the muscle |
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Term
T/F
Injecting lidocaie and curare straight into the muscle will have no effect on muscle contraction |
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Definition
T
Lidocain stops muscle contraction by stabilizing the lipid bilayer and freezing ion channels
Curare stops muscle contraction by binding to N2 and preventing Na+ channels from opening
Both of these things happen before the impulse reaches the muscle, so if we inject them directly into the muscle, there is no effect. |
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Term
property by which the impulse that initiates muscle contraction originates within the muscle itself rather than in response to input from nerve impulses
e.g. smooth muscle |
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Definition
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specialized cells in smooth muscle that spontaneously depolarize, allowing smooth muscle to be myogenic
___________ membrane is more permeable to Na+ and Ca++ |
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Definition
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slow movement of Na+ and Ca++ leaking across the membrane into the muscle cell, depolarizing the membrane
usually occurs ~12 times per minute
lasts for 5 seconds |
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Definition
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| In smooth muscle, at threshold, it is mostly ____ channels that open |
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Definition
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| How long is an AP in smooth muscle? |
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Definition
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| __________ acts as a pacemaker for smooth muscle contraction |
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Definition
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T/F
Although smooth muscle does not need nervous input to initiate a contraction, nerves from the autonomic nervous system modify both the strength and frequency of contraction. |
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Definition
T
sympathetic and parasympathetic nerves! |
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Term
| Effect of stimulating sympathetic nerves on muscle contraction? |
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Definition
inhibits muscular activity
sympathetic = fight or flight |
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Term
| Effect of stimulating parasympathetic nerves on muscle contraction? |
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Definition
initiates muscular activity
parasympathetic = rest and digest |
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Definition
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| connects cranium to spinal cord |
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Definition
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| connects spinal cord to muscle |
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Definition
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| Describe pre and post-ganglionic fiber length in para and sympathetic nervous systems |
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Definition
sympathetic: short pre-ganglionic
parasympathetic: long pre-ganglionic
(and vice versa) |
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| What neurotrasmitter does the PRE-ganglionic fiber secrete in the SYMPATHETIC system? |
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Definition
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| What neurotrasmitter does the PRE-ganglionic fiber secrete in the PARASYMPATHETIC system? |
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Definition
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| What type of receptor is at the coeliac ganglion of the SYMPATHETIC system? |
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Definition
| type 1 nicotonic receptor (N2) |
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Term
| What type of receptor is at the coeliac ganglion of the PARASYMPATHETIC system? |
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Definition
| type 1 nicotinic receptor (N2) |
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| What neurotrasmitter does the POST-ganglionic fiber secrete in the PARASYMPATHETIC system? |
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Definition
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| What neurotrasmitter does the POST-ganglionic fiber secrete in the SYMPATHETIC system? |
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Definition
| Epinephrine and norepinephrine |
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| What type of receptor is in the smooth muscle of the SYMPATHETIC system? |
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Definition
alpha2 and beta2
(2 means inhibitory, 1 means excitatory) |
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| What type of receptor is in the smooth muscle of the PARASYMPATHETIC system? |
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Definition
muscarinic receptor (type 1 excitatory)
mmm muscadines |
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Term
| How does epinephrine inhibit muscle activity in smooth muscle? |
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Definition
| Epinenprhine binds to alpha2 and beta2 receptors which activates K+ channels, hyperpolarizing the membrane |
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Term
| How does Ach initiate muscle activity in smooth muscle? |
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Definition
| Ach binds with muscarinic receptors, activating Na+ and Ca++ channels, depolarizing the membrane |
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Term
| Give 4 examples of smooth muscle |
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Definition
1. intestines
2. alimentary canal vasculature
3. bladder
4. uterus |
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Term
T/F
Smooth muscle is unstriated |
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Definition
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Term
T/F
Smooth muscle fibers are coupled together |
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Definition
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| property by which the impulse that initiates muscle contraction originates in the CNS |
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Definition
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T/F
Ca++ channels are always open in smooth muscle |
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Definition
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| What effect will adding Ach to smooth muscle have on muscle activity? |
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Definition
| increases muscle activity |
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Term
| muscle "tone" is actually an increase in _____ ______ |
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Definition
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Term
| What effect will adding physostigmine to smooth muscle have on muscle activity? |
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Definition
physostigmine is an ANTI-AchE
inhibits AchE --> increase Ach --> increase in muscle activity |
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Term
| What effect will adding atropine to smooth muscle have on muscle activity? |
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Definition
| atropine blocks mAch --> decrease muscle activity |
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| What is physostigmine and how does it affect muscle activity? |
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Definition
anti-AchE
- inhibits AchE
- increases Ach |
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| What is atropine and how does it affect muscle activity? |
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Definition
| mAch blocker --> decrease muscle activity |
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| What effect with adding NaN3 to smooth muscle have on muscle activity? |
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Definition
NaN3 (toxin) dissolves in solution into Na+ and Na3-
increased Na+ --> "free sodium effect" (inc. contractile activity)
N3- decouples ETC --> shuts down ATP production --> no ATP to power oxidative phosphorylation --> YOU DIE |
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