Term
What does EPSP stand for?
What does IPSP stand for? |
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Definition
Excitatory Post-Synaptic Potentials
Inhibitory Post-Synaptic Potentials |
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Term
| What are EPSPs and IPSPs? |
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Definition
| The small changes in inside voltage when a packet of transmitter binds to the membrane of the receiving postsynaptic cell. |
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Term
EPSPs are....
IPSPs are....
Depolarizing/Hyperpolarizing |
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Definition
EPSPs- Depolarizing
IPSPs- Hyperpolarizing |
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Term
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Definition
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Term
| The motor end plate is constructed to produce an action potential... |
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Definition
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Term
| With each action potential from the axon... |
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Definition
| there is a massive release of trasmitter, ACh, into the cleft |
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Term
| Everytime there is a massive release of trasmitter, ACh, into the cleft... |
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Definition
| ACh bind to ACh receptor proteins on the muscle membrane |
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Term
| After ACh bind to ACh receptor proteins on the muscle membrane... |
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Definition
| All Gated Na+ ion channels in the muscle membrane open |
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Term
| After all Gated Na+ ion channels in the muscle membrane open... |
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Definition
| There is an in-rush of Na+, which depolarized the muscle membrane past threshold |
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Term
| After there is an in-rush of Na+, which depolarized the muscle membrane past threshold... |
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Definition
| Action Potential begins in postsynaptic membrane of the muscle cell |
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Term
| After an action Potential begins in postsynaptic membrane of the muscle cell... |
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Definition
| The chemical signal, ACh, it turned "off" by cholinesterase enzyme in the postsynaptic muscle membrane |
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Term
| What are the two synaptic poisons? |
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Definition
1. Curare, which binds to and blocks ACh receptors, but does not depolarize
2. Succinyl Choline, which binds to and blocks ACh receptors |
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Term
Neither Curare or Succinyl Choline are...
They are active for about how long? |
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Definition
broken down by cholinesterase enzyme
10-15 minutes |
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Term
| Muscle fibers are also known as... |
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Definition
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Term
| A bundle of fibers forms a.... |
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Definition
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Term
| Groups of fasciculi form the... |
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Definition
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Term
| Muscle cells are syncitial, which means... |
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Definition
| many nuclei in one cell, prepresenting nuclear replication without cell division |
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Term
| What is the unit of contraction? |
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Definition
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Term
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Definition
| One unit of contraction, defined by the structures between two Z-lines |
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Term
| Z-lines are the same thing as.. |
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Definition
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Term
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Definition
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Term
| Thick filaments are made up of 1. and held together by 2. . |
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Definition
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Term
| Thin filaments are made up of 1. and held together by 2. . |
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Definition
1.Actin (Actinin)
2. Z-lines |
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Term
| What band disappears when the muscles contract? |
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Definition
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Term
| What units are included in a sarcomere? |
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Definition
| Two Z-bands on the outside with an M-line/disk in the middle surrounded by the H-band and A-bands on either side. |
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Term
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Definition
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Term
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Definition
Myosin thick filaments, containing H-bands, and held together by M-disks.
They are the dark part of muscle, and all are the same size |
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Term
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Definition
| The "handles" of golf-club-like myosin filaments, surrounded by A-bands, and held together by M-disks |
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Term
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Definition
| A grid of myosin-binding proteins to hold thick filaments in place, which hold H-bands (myosin filaments) in place, which are surrounded on either side by myosin thick-filaments known as A-bands. |
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Term
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Definition
The exposed actin thin filaments, split by the Z-line or Z-disk.
I-bands differ in size |
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Term
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Definition
| grid of actin-binding proteins to hold thin filaments in place, like I-bands, which are exposed actin thin filaments. |
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Term
| 1. filaments do the grabbing of the 2. filaments, meaning they move the muscle. |
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Definition
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Term
| What are the striations of skeletal muscles? |
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Definition
| Stacks of millions of proteins strands in register in the muscle cell |
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Term
| What are the protein components which make up the thin "actin" filament? (3) |
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Definition
1. Actin Monomers
2. Tropomyosin (strings)
3. Troponins (TnI, TnC, TnT) |
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Term
| Each thick filament is made up of of many 1. , shaped like 2. , with the shaft formed of two 3. . |
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Definition
1. myosin protein monomers
2. two-headed golf clubs
3. twisted protein chains |
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Term
| The head assembly of the "golf-club" myosin thick filament is called... |
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Definition
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Term
| The "handle" of the golf-club myosin thick filament is known as... |
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Definition
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Term
| Are the myosin protein club ends flexible, or inflexible? |
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Definition
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Term
| Each myosin protein club end has 3 active sites which perform the following 3 actions: |
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Definition
1. one site binds ATP
2. one site cleaves ATP
3. one site binds to the actin protein |
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Term
| What is blocking the myosin head from contacting the actin and contracting the muscle? |
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Definition
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Term
| When Ca2+ is released into the cytoplasm, what happens next? |
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Definition
| The Ca2+ binds to the troponin C, which then bends the tropomyosin out of the way, which exposes a myosin binding site on the actin filament. The club then makes contact, binds to the actin, and pulls the actin to the left, thus starting the contraction cycle. |
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Term
| Sequence of Events during Contraction: |
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Definition
1. ATP binds in ATP-binding slots on myosin heads
2. Myosin binding site to actin filament breaks
3. ATP is broken down by myosin ATPase Enzyme into ADP and a phosphate group (PO43-)
4. Heads are "cocked" into extended position
5. Head makes connection with new actin subunit
6. Head snaps into bend position, pulling on the actin
7. New molecule of ATP binds to slot in byosin head
8. Binding site to actin breaks... |
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Term
| Where did the Calcium used in the contraction cycle come from? |
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Definition
| It was stored in the sarcoplasmic reticulum |
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Term
| What is the sarcoplasmic reticulum? |
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Definition
An enclosed membrane system that lies entirely within the muscle cell/fiber, but comes into very close contact with the cell membrane through the cells transverse tubules.
Ca2+ ion trap that pumps calcium into the cell against the gradiant |
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Term
| The SR's calcium ion pumps continuously move calciums ions from the 1. around the 2. into the SR, making the SR's inside [Ca2+] very 3. compared to the rest of the cell. |
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Definition
1. Cytoplasm
2. Sarcomeres
3. High |
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Term
| When an action potential travels over the muscle cell membrane, it 1. down the 2. , which then 3. . |
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Definition
1. Propagates
2. Transverse Tubules
3. Open the voltage-gated Ca2+ channels, releasing a flood of Calcium ions into the nearby sarcomeres to start a contraction |
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Term
| As soon as the action potential is over, what happens to the calcium channels? |
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Definition
| The calcium channels close, and the SR's calcium pumps vacuum up the ions inside the SR |
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Term
| Sequence of Events in Excitation & Contraction of Skeletal Muscles: Up until the contraction |
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Definition
1. Above-threshold stimulus (from CNS)
2. Action Potential starts in motor-nerve soma (cell body)
3. Propagation of AP down myelinated motor axon by saltatory propagation via nodes of ranvier
4. Depolarization of synaptic ending of motor nerve, the motor end-plate
5. Release of ACh at motor endplate
6. Binding of ACh to post-synaptic (muscle) membrane's ACh binding sites
7. Opening of sodium channels in muscle membrane
8. Action potential in muscle membrane
9. Propagation of AP down transverse (T) tubules into muscle-cell interior
10. Opening of calcium ion channels in SR membranes
11. Release of SR-trapped calcium ions into cytoplasm surrounding myofibrils
12. Binding of calcium ions to troponin C of actin (thin) filaments pulls tropomyosin out of the way |
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Term
| Secquence of Events in Excitation & Contraction of Skeletal Muscle: Beginning of Contraction to the Stopping of Contraction |
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Definition
1. "Cocked" myosin heads "fire" and pull actins toward center of the sarcomere.
2. New ATP molecule binds to myosin at the ATP binding site at the club end
3. Myosin's contact to actins break
4. Recently-bound ATP is cleaved by myosin ATPase Enzyme
5. Club end is "cocked" in new position
6. New contact forms betwee myosin head and actins
7. "Cocked" myosin heads "fire" and pull actins toward center of sarcomere
8. New contacts form and break as contraction continues... |
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Term
| Sequence of Events in Excitation and Contraction of Skeletal Muscle: Contractions stop |
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Definition
1. Nerve depolarization stops
2. Muscle Membrane depolarization stops
3. Calcium ion release from SR stops
4. Calcium is actively pumped back into the SR
5. Tropomyosin blocks actin binding sites
6. No new contacts form
7. Excess ATP in cell binds to myosin head's ATP binding sites
8. Remaining contacts break
9. Muscle relaxes |
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Term
| What are the two types of skeletal muscle contraction? |
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Definition
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Term
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Definition
| A single contraction caused by a single action potential over the muscle |
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Term
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Definition
| A sustained contraction without any relaxtion caused by multiple action potentials over the muscle. |
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Term
| What are the two types of tetanic contractions? |
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Definition
1. Isometric- contraction force measure while the muscle is not allowed to shorter (length does not change)- holding yourself in an extended arm hang
2. Isotonic- contraction force measure while muscle is under constant load, but allowed to shorten- holding chin up in bent arm hang |
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Term
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Definition
Contracture= cramps
>200 AP's/sec |
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Term
| What are the limits to the force of tetanic muscle contraction? (4) |
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Definition
1. Duration of stimulation
2. Number of action potentials stimulating muscle per second
3. Size of Muscle fiber
4. ATP supplies |
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Term
Describe why tetanic muscle contraction is limited by:
Duration of Stimulation |
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Definition
(time the calcium ion is free in the cytoplasm)
-gives time to stretch out passive elastic elements
-gives time for myosin heads to engage more actin binding sites
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Term
| What are passive elastic elements? |
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Definition
| Membranes and connective tissue holding muscle cells together |
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Term
Describe why tetanic muscle contraction is limited by:
Number of Action Potentials Stimulation Muscle per Second |
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Definition
| Determines the amount of calcium ion released from the SR; a function of the brain on spinal motor nerves (normally, ca. 80 ap's per sec up to 300 per sec) |
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Term
| Describe why tetanic muscle contraction is limited by: Size of Muscle Fiber |
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Definition
| Determines the amount of myosin (heads) per cell -> amt. of myosin ATPase/cel ->ability to form crossbridges with actin |
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Term
| Describe why tetanic muscle contraction is limited by: ATP supplies |
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Definition
| It's related to the number of mitochondria per cell, the oxygen supply to the cell; number and distribution of capillaries (angiogenesis) |
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Term
| Why does the oxygen supply to the cell matter in tetanic muscle contraction? |
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Definition
Glycolysis without O2 yields 2 ATP's per molecule of glucose used.
Glycolysis along with mitochondrial Kreb's cycle oxydation yields 38 ATP's per molecule of glucose used. |
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Term
| The "Length-tension Relationship" hold for what type of muscles only? |
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Definition
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Term
| What is the Length-Tension Relationship? |
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Definition
| When a muscle is passively stretched, then stimulated, it contracts with greater force--within limits. |
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Term
| What is the similar relationship to the "Length-Tension Relationship" that applies to the cardiac muscle? |
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Definition
| The Frank-Starling Law of the Heart |
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Term
| As the frequency of stimulation increases, the muscle goes from complete relaxation between contractions 1. to incomplete relaxation 2. and incomplete relaxation with greater force 3. to sustained contraction with no relaxation 4. . |
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Definition
1. Twitch
2. Fusion
3. Summation
4. Tetanus |
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Term
| Each small motor nerve is synapsed to... |
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Definition
| A small number of small (low-force, slow, high-endurance) muscle fibers/cells. |
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Term
| Each large motor nerve is synapsed to... |
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Definition
| A large number of large (high-force, fast, low-endurance) muscle fibers/cells |
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Term
| The smaller the motor nerve, the 1. it is to excite... |
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Definition
1. easier
i.e. to get it to depolarize and get past threshold -> action potential |
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Term
| The larger the motorl nerve, the 1. it is to excite. |
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Definition
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Term
| The idea that smaller motor nerve are easier to excite, and larger motor nerves are harder to excite is an example of... |
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Definition
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Term
| Most major muscles of the skeleton are 1. ; i.e., made up of small, intermediate and large muscle fibers. |
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Definition
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Term
| "Commands" (action potentials) from.. |
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Definition
| Motor centers of cortex and basal ganglia converge on motor nerve cell bodies in the anterior horn of the spinal cord |
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Term
| The first motor nerves to fire are the 1. , which activate 2. . The last to fire are the 3. , which activate 4. . |
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Definition
1. smallest
2. a small number of low-force, slow, high-endurance muscle cells in a particular cell
3. largest
4. a large number of high-force, fast, low-endurance muscle cells in the same muscle |
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Term
| In order to get to the 1. muscles, you must excite the 2. first. |
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Definition
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Term
| Contraction force rises slowly, then as large motor units "kick in", force.... |
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Definition
rises rapidly (exponentially)
Look at pg 26 |
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Term
Comparison of 3 types of Skeletal Muscle Fibers:
Color= myoglobin concentration |
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Definition
Red/Slow Twitch: Red (high myoglobin)
Red/Fast Twitch: Red (high myoglobin)
Pale/Fast Twitch: White/pale (low myoglobin) |
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Term
Comparison of 3 types of Skeletal Muscle Fibers:
Diameter of Muscle Fiber |
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Definition
Red/Slow Twitch: Small
Red/Fast Twitch: Intermediate
Pale/Fast Twitch: Largest |
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Term
Comparison of 3 types of Skeletal Muscle Fibers:
Speed of Contraction |
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Definition
Red/Slow Twitch: Slow
Red/Fast Twitch: Fast
Pale/Fast Twitch: Fastest |
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Term
Comparison of 3 types of Skeletal Muscle Fibers:
Force of Contraction |
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Definition
Red/Slow Twitch: Low
Red/ Fast Twitch: Intermediate
Pale/Fast Twitch: Highest |
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Term
| Comparison of 3 types of Skeletal Muscle Fibers: total Myosin ATPase Enzyme Activity |
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Definition
Red/Slow Twitch: Low
Red/Fast Twitch: High
Pale/Fast Twitch: Highest |
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Term
Comparison of 3 types of Skeletal Muscle Fibers:
Mitochondria, per unit volume |
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Definition
Red/Slow Twitch: High (a lot of ATP produced)
Red/ Fast Twitch: High (a lot of ATP produced)
Pale/Fast Twitch: Low |
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Term
| Comparison of 3 types of Skeletal Muscle Fibers: Predominant Pathways for ATP Production |
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Definition
Red/Slow Twitch:Oxidative Phosphorylation using Mitochondria
Red/Fast Twitch:Oxidative Phosphorylation using Mitochondria
Pale/Fast Twitch: Anaerobic Glycolysis |
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Term
Comparison of 3 Types of Skeletal Muscle Fibers:
Capillary Vascularization |
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Definition
Red/Slow : Rich
Red/Fast: Rich
Pale/Fast: Poor |
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Term
Comparison of 3 Types of Skeletal Muscle Fibers:
Resistance to Fatigue |
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Definition
Red/Slow: High Endurance
Red/Fast: High Endurance
Pale/Fast: Low Endurance |
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Term
Comparison of 3 Types of Skeletal Muscle Fibers:
Size of Motor Nerve Innervating Muscle Cells |
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Definition
Red/Slow: Small (slower propagation)
Red/Fast: Large (faster propagation)
Pale/Fast: Largest (fastest propagation) |
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Term
Comparison of 3 Types of Skeletal Muscle Fibers:
Size of Motor Unit in Spinal Cord |
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Definition
Red/Slow: Small
Red/Fast: Large
Pale/Fast: Largest |
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Term
Comparison of 3 Types of Skeletal Muscle Fibers:
Exciteability of Motor Nerves |
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Definition
Red/Slow: High, first to fire AP
Red/Fast: Low/Intermediate
Pale/Fast: Low, last to fire |
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Term
| How many ATP does Oxidative Phosphorylation create? |
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Definition
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Term
| How many ATPs does Anaerobic Gycolysis create? |
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Definition
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Term
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Definition
| 1 motor nerve and all the muscle fibers it innervates |
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