Neuromuscular System-sem 2 Yr 1
Test one for the neuromsk skel syst 2010 semester 2
- 1.
Where and when does the myosin crossbridge attach?
- A.
On troponin when calcium is low
- B.
On troponin c when calcium is high
- C.
On actin when calcium is high
- D.
On the sarcomere when sodium is high
- E.
On actin when calcium is low
Correct Answer
C. On actin when calcium is highExplanation
calcium binds to troponin C which changes conformation uncovering the actin to allow myosin attachment. This site remains blocked when calcium is lowRate this question:
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- 2.
Fiber types within the skeletal muscle generating force and movement are?
- A.
Intrafusal
- B.
Thick filament
- C.
Extrafusal
- D.
Thin filament
- E.
Nuclear chain fibers
Correct Answer
C. ExtrafusalExplanation
extrafusal are the series of linked sarcomeres (z line-zline)(thick myosin and thin actins) the shortening of sarcomeres generates force and movement via alpha motor neuron AP>release of ACh>binds to nicotinic receptoe>EPP>AP in musc membrane
intrafusal=not controlled by alpha motor neuron-even though actin and myosin
parallel to extrafusal
nuclear chain fibers wrap around end of intrafusal as sensory nerve fibers along with nuclear bag fibers- they report musc contraction status via gamma Efferents
they are regulators-adjusting sensitivity of sensory system
they influence flow of info through 1A and 11 AfferentsRate this question:
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- 3.
What does the process of active state require?
- A.
Extracellular calcium increase
- B.
Intracellular calcium increase
- C.
Intracellular calcium increase and ATP
- D.
Extracellular calcium decrease
- E.
ATP
Correct Answer
C. Intracellular calcium increase and ATPExplanation
hypercalcemia can cause a sodium channel blocking effect thus causing flaccid paralysis
hypocalcemia cause the oposite with spontaneous opening of the Na channels due to voltage flux the result is spasticity
so intracellular ca is used from the SR but to retrieve it requires a pump for active transport- this requires ATPRate this question:
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- 4.
Contraction is the result of:
- A.
An incease number of crossbridge attachments
- B.
Calcium at its basal level
- C.
An increase of actin filaments
- D.
Decreasing extracellular calcium
- E.
Loss of ATP
Correct Answer
A. An incease number of crossbridge attachmentsExplanation
increase intracellular Ca=increase # of crossbridge =increase forceRate this question:
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- 5.
Where is the storage facility of ATP in the sarcomere?
- A.
Calcium
- B.
Sodium
- C.
Actin
- D.
Myosin
- E.
Troponin C
Correct Answer
D. MyosinExplanation
binding of crossbridges triggers the release of energy that is stored in the myosin-it is the rotation of the myosin headRate this question:
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- 6.
If the muscle ends are clamped at a fixed length prior to the contraction, and the muscle length cannot decrease as the muscle's cell contract, is it :
- A.
Concentric contraction
- B.
Isotonic contraction
- C.
Eccentric contraction
- D.
Auxotonic contraction
- E.
Isometric contraction
Correct Answer
E. Isometric contractionExplanation
isotonic includes concentric (bicep curl) and eccentric (a overly heavy weight) it has a change in lenght of muscle but the tension remains constant
auxotonic is a contraction with some flux at the end like with ventricles pumping the blood out
isometric is right because there is no change in length but force is generated such as hand gripsRate this question:
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- 7.
What is the signal for contraction?
- A.
Sodium
- B.
Actin
- C.
Myosin
- D.
Calcium pulse
- E.
Twitch
Correct Answer
D. Calcium pulseExplanation
calcium pulse from the SR-There is no calcium current across the cell membrane in SKELETAL muscle during action potential (opposite from cardiac and smooth muscle =incease calcium in blood gives flaccid paralysis of skeletal muscle and increase activity of smooth and cardiac muscleRate this question:
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- 8.
What second messenger is involved in the binding of myosin to actin in skeletal muscle and cardiac muscle
- A.
Calcium
- B.
Tropomyosin
- C.
Troponin c
- D.
Myosin
- E.
ATP
Correct Answer
A. CalciumExplanation
Calcium is the correct answer because it acts as a second messenger in the binding of myosin to actin in skeletal and cardiac muscle. When calcium ions are released into the muscle cell, they bind to troponin C, which causes a conformational change in the troponin-tropomyosin complex. This change allows myosin to bind to actin, initiating muscle contraction. Without the presence of calcium, the binding of myosin to actin cannot occur, and muscle contraction cannot be initiated.Rate this question:
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- 9.
When is ATP initially used in the crossbridge cycle?
- A.
In rigor mortis
- B.
In relaxation
- C.
In excitation
- D.
In hydrolysis
- E.
In product release
Correct Answer
B. In relaxationExplanation
ATP is used in binding Myosin head to actin and the E is stored in the headRate this question:
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- 10.
What is the most efficient method of ATP generation?
- A.
Glycolysis
- B.
Phosphorylation
- C.
Gluconeogenesis
- D.
Oxidation of fatty acids
- E.
Chemiosmosis
Correct Answer
D. Oxidation of fatty acidsExplanation
oxidation of fatty acids is the slowest but most efficient
phosphorylation is fast but a temporary fix while waiting for permanent
glycolysis is fast but inefficientRate this question:
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- 11.
A muscle showing to have a slow myosin isoenzyme (ATPase rate)/contraction timemoderate Sr pump capacitymoderate diffusion diametersmall motor neuron sizehigh oxidative capacity:mt content, capillary density,myoglobin contenthigh fatigue resistancemoderate glycolytic capacitylow forceaerobic activitytriglycerides as storage fuelis what type?
- A.
Type 11B/ fg/ ft-b/fast glycolytic/white
- B.
Type 11A/fog/ft-a/fast oxidative/red
- C.
Type 1/so/slow oxidative/white
- D.
Type 1A/fog/ft-a/fast oxidative/red
- E.
Type 2/so/slow oxidative/white
Correct Answer
C. Type 1/so/slow oxidative/whiteExplanation
The given characteristics indicate that the muscle has a slow myosin isoenzyme, moderate Sr pump capacity, moderate diffusion diameter, small motor neuron size, high oxidative capacity (mt content, capillary density, myoglobin content), high fatigue resistance, moderate glycolytic capacity, low force, aerobic activity, and triglycerides as storage fuel. These characteristics are consistent with type 1 muscle fibers, also known as slow oxidative (SO) or white fibers. These fibers are characterized by their slow contraction speed, high endurance, and reliance on aerobic metabolism.Rate this question:
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- 12.
A muscle showing to have a very fast myosin isoenzyme (ATPase rate)/contraction timehigh Sr pump capacityhigh diffusion diametervery large motor neuron sizelow oxidative capacity:mt content, capillary density,myoglobin contentlow fatigue resistancehigh glycolytic capacityvery high forceshort term aerobic activitycp,O2 as storage fuelis what type?
- A.
Type 11B/ fg/ ft-b/fast glycolytic/white
- B.
Type 11A/fog/ft-a/fast oxidative/red
- C.
Type 1/so/slow oxidative/white
- D.
Type 1A/fog/ft-a/fast oxidative/red
- E.
Type 2/so/slow oxidative/white
Correct Answer
A. Type 11B/ fg/ ft-b/fast glycolytic/whiteExplanation
The given answer, type 11B/ fg/ ft-b/fast glycolytic/white, is the correct answer because the characteristics mentioned in the question align with the traits of type 11B muscle fibers. These fibers have a very fast myosin isoenzyme (ATPase rate), high glycolytic capacity, low oxidative capacity, low fatigue resistance, and high force production. They also have a high diffusion diameter, high Sr pump capacity, and very large motor neuron size. These characteristics indicate that the muscle is designed for short-term, high-intensity activities and relies on anaerobic metabolism for energy production. Additionally, the reference to "white" in the answer refers to the color of these muscle fibers due to their low myoglobin content.Rate this question:
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- 13.
A muscle showing to have a fast myosin isoenzyme (ATPase rate)/contraction timehigh Sr pump capacitysmall diffusion diameter large motor neuron sizevery high oxidative capacity:mt content, capillary density,myoglobin contentmedium fatigue resistancehigh glycolytic capacityv high forcelong term aerobic activitycp,O2 as storage fuelis what type?
- A.
Type 11B/ fg/ ft-b/fast glycolytic/white
- B.
Type 11A/fog/ft-a/fast oxidative/red
- C.
Type 1/so/slow oxidative/white
- D.
Type 1A/fog/ft-a/fast oxidative/red
- E.
Type 2/so/slow oxidative/white
Correct Answer
B. Type 11A/fog/ft-a/fast oxidative/redExplanation
The given characteristics suggest that the muscle is type 11A, also known as fog/ft-a, which refers to fast oxidative/red muscle fibers. These fibers have a high oxidative capacity, indicated by factors such as mt content, capillary density, and myoglobin content. They also have medium fatigue resistance and high glycolytic capacity. The presence of a fast myosin isoenzyme (ATPase rate) and a large motor neuron size further supports the classification of the muscle as type 11A.Rate this question:
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- 14.
After a muscle relaxes and the compression of the vessels are relieved there is a sustained increase in blood flow. This is called?
- A.
Hypertrophy
- B.
Hypoxia
- C.
Maximal voluntary contraction
- D.
Reactive hyperemia
- E.
Hyporemia
Correct Answer
D. Reactive hyperemiaExplanation
hypertrophy is the increase in the volume of an organ
hypoxia is O2 deficiency
maximal voluntary contraction a muscle that exerts more than 70% of its maximal force (compresses blood flow
reactive hyperemia is the right answer and
hyporemia is made upRate this question:
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- 15.
Energy expenditure that is greater than oxidative resupply of enegy during exercise is called:
- A.
Oxygen deficit
- B.
Oxygen debt
- C.
Hypoxia
- D.
Hyperemia
- E.
Oxygen depletion
Correct Answer
A. Oxygen deficitExplanation
hyperemia is blood flow
hypoxia and oxygen depletion may cause oxygen defict
O2 debt is the culmination of O2 deficitsRate this question:
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- 16.
Which motor units are recruited first?
- A.
Small
- B.
Type 2
- C.
Medium
- D.
Type 1
- E.
Large
Correct Answer
D. Type 1Explanation
type 1 are small diam fast conduction velocity, and High excitability (easy start) they have few fibers and low contraction force / unit (they are small) they are oxidative and are low fatigue
type 2 are largr, very fast, hard (low) excitability, they have many fibers and have high contraction force, they are glycolytic and high for fatigue
there are no "small, medium, or large"Rate this question:
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- 17.
Which is not a primary cause of cellular fatigue in the muscle cell?
- A.
Increased intracellular ADP
- B.
Metabolic waste- lactic acid and phosphate
- C.
Slowed type 2 motor units
- D.
Depletion of ACh
- E.
Increased intracellular potassium
Correct Answer
C. Slowed type 2 motor unitsExplanation
the type 2 are the first to stop at which point the type 1 will continue-albiet slower and with less force-but primary is the key wordRate this question:
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Mar 21, 2023Quiz Edited by
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Apr 23, 2010Quiz Created by
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