Term
| What are the 3 types of muscles |
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Definition
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Term
| Muscle mass comprises approx ___% of the horse's body weight |
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Definition
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Term
| Describe the # of mitochondria in cardiac, skeletal and smooth muscle |
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Definition
Cardiac: high #
Skeletal: variable
Smooth: low # |
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Term
| Which muscle types have high resistance to fatigue? |
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Definition
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Term
| The muscle cell membrane is known as the... |
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Definition
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Term
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Definition
| filament within a muscle cell |
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Term
| What attaches muscle do bone |
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Definition
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Term
| What is the functional centre of myosin filaments? |
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Definition
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Term
| What is the region of overlap between the I-band & H-band? |
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Definition
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Term
| What is found in the I-band? H-band? |
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Definition
I: actin filaments
H: myosin filaments |
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Term
| As # of fibres innervated by a neuron increases, magnitude of force produced by the muscle _____ |
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Definition
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Term
| Which have a higher threshold, nerves with narrow diameter or wide? |
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Definition
| wide diameter have higher threshold |
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Term
| Do narrow nerve fibers or wide fibers offer a fine motor control? |
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Definition
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Term
| Where is calcium stored in muscle cells? What triggers its release? What does its release trigger |
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Definition
sarcoplasmic reticulum
-release triggered by AP in T-tubules
-release of Ca triggers contraction of sarocomeres |
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Term
| Describe depolarization of a muscle nerve cell |
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Definition
1. AChR channels open, Na enters cell
2. Na entry triggers release of voltage-dep Na channels
3. T-system depolarizan triggers Ca2+ release from SR
4. Contraction initiated |
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Term
| Are sodium channels energy or gradient dependent? |
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Definition
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Term
| For every __ sodium moving out through the Na:K pump, __ K move in |
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Definition
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Term
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Definition
| stimulation of a muscle nerve before repolarization has completed triggering a 2nd contraction with greater tension |
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Term
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Definition
| When a muscle enters a tetanic state (cramped) in a constant state of contraction |
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Term
| What is the long protein wrapped around an actin filament |
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Definition
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Term
| What is troponin? What does it do? |
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Definition
TrC, TrI & TrT proteins embedded within tropomyosin
-regulates binding of myosin heads to actin filaments |
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Term
| How is Ca involved in the troponin/tropomyosin interaction? |
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Definition
| Ca interacts with troponin, inducing conformational change in tropomyosin allowing myosin heads to bind to actin |
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Term
| How is ATP involve in contraction? |
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Definition
-binds to myosin head
-hydrolysis will release ADP, energy allows myosin head to crawl along actin filament
-ATP binds to myosin again, causing it to detach from actin |
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Term
| What checkpoints in the contraction/relaxation cycle require ATP? |
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Definition
myosin head conformational change
Na:K pump
Ca pump |
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Term
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Definition
Recurrent Exertional Rhabdomyolysis
-tying up
-associated with intense exercise
-defect in intracellular Ca regulation |
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Term
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Definition
Polysaccharide Storage Myopathy
-mutation in GYSI gene (glycogen synthase)
-can form & store glycogen but cannot access it, accumulates in skeletal muscle
-lower AP threshold stimulus |
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Term
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Definition
Hyperkalemic Periodic Paralysis
-defect in Na channels
-leaky mmb allowing excess Na to enter cell
-increases K outside cell, reducing mmb potential triggering contraction |
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Term
True or False
Actin has ATPase activity |
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Definition
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Term
| Do fast fibers rely on anaerobic or aerobic pathways? |
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Definition
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Term
| Are Type I, Type IIB and Type IIA fast or slow twitch muscles? Low or high oxidative? Which of the fast-twitch are fatigue-resistant? |
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Definition
Type I: slow twitch, low oxidative
Type IIB: fast twitch, low oxidative
Type IIA: fast twitch, high oxidative, fatigue-resistant |
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Term
| Which type of muscle fibers would be used for long, slow physical activity? |
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Definition
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Term
| Which has more muscle fibers per nerve, Type I or Type II? |
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Definition
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Term
| How many net ATP are produced during anaerobic ATP production? |
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Definition
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Term
| How long does it take for a horse to restore glycogen stores after exhaustive exercise? |
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Definition
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Term
| When is phosphocreatine used for ATP production? |
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Definition
| at onset of exercise and during sporadic periods of high intensity |
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Term
| Why is anaerobic ATP production self-limiting? |
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Definition
-need NAD to feed G3P
-glycogen is depleted and takes 72h to restore
-lactic acid production lowers pH, inhibiting enzymes involved in glycolysis |
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Term
| How many ATP are produced during aerobic production? |
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Definition
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Term
| What are the muscle substrates for aerobic ATP production? |
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Definition
glycogen
palmitic acid (fat) |
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Term
What do the following RER indicate:
0.7
1.0 > RER > 0.7
1 |
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Definition
0.7: free fatty acids are being used
1.0 > RER > 0.7: CHO and FFA being used
1: CHO is being used, fully oxidized |
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Term
| Why does it take longer to use fat as an energy source? |
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Definition
| must first mobilize it & bring to the muscle |
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Term
True or False
PSSM horses are insensitive to insulin |
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Definition
False
highly sensitive
-triggers storage of CHO as glycogen but cannot use effectively |
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Term
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Definition
| low pH and high CO2 during exericise stimulates 'downloading' of O2 from hemoglobin, replacing it with H+ or CO2 to moderate pH levels |
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Term
| What percentage of energy released with ATP is hydrolyzed is used for mechanical work? |
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Definition
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Term
| What causes muscle soreness during/after exercise? |
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Definition
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Term
True or False
Lactate is essential for sprinting |
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Definition
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Term
| Why is lactate important? |
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Definition
converted to pyruvate using lactate dehydrogenase, producing NAD+
-lactate provides fuel for mitochondria |
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Term
| How long does it take for physiological responses to be improved with training? |
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Definition
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Term
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Definition
| abnormal adaptations to excessive stress |
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Term
| What is the role of cortisol during stress? |
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Definition
| prepares the body for glycogen sparing |
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Term
| Fatigue due to sub-maximal exercise is usually due to... |
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Definition
depletion of glycogen stores
hyperthermia |
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Term
| Fatigue due to high intensity exercise is usually due to... |
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Definition
depletion of PCr & ATP
acidosis |
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Term
| what effect does a K imbalance have on muscle function? |
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Definition
| impairs perfusion of muscles with blood, reducing ability to remove metabolic waste/provide nutrients |
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Term
| What effect does a Ca/Mg imbalance have on muscle function? |
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Definition
sensitives the phrenic nerve, causing the diaphragm to contract at the same rate as the heart
(the thumps) |
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Term
| What effect do imbalances of Na/Cl/K/Mg have on muscle function? |
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Definition
| impairs distribution of electrical charge across cell membranes |
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Term
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Definition
| feeding sodium bicarbonate to increase pH of blood and muscle, facilitating lactate eflux and sparing the use of ATP (prolonging fatigue) |
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Term
| What meets the glucose needs of an organism as a whole? |
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Definition
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Term
| What meets the glucose needs of specific muscles? |
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Definition
| the glycogen stored in the muscle in question |
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Term
| How does glycogen provide energy? |
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Definition
| broken down to G-6-P, used in glycolysis for ATP & NADPH production |
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Term
| Why does it take so long to restore glycogen levels in a horse post-exercise? |
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Definition
| exhaustive exercise does not trigger a spike in insulin, which is required to increase uptake of glucose from the blood to be stored as glycogen |
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Term
| What effect does low muscle glycogen have on muscle contraction? |
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Definition
impaired the release of Ca2+ from the SR
-less response from T tubules to depolarization |
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Term
| What effect does acetate have on restoring muscle glycogen? |
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Definition
| increases storage levels 4h after exercise, but no net gain 24h post exercise |
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Term
| What effect do electrolytes have on restoring muscle glycogen? |
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Definition
| increases rate of post-exercise glycogen resynthesis |
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