$$3\text{Na}^+ \text{out} : 2\text{K}^+ \text{in}$$

The membrane potential must reach threshold at $$-55\text{mV}$$

$$\text{Glucose} + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + 36\text{ATP}$$

Question 1

Which muscle tissue type is characterized by involuntary control, branched fibers, striations, and intercalated discs?

Accepted Answer

Cardiac muscle

Question 2

What is the primary function of the sarcoplasmic reticulum in skeletal muscle fibers?

Accepted Answer

Stores calcium ions for muscle contraction

Question 3

During muscle contraction, which event directly exposes the myosin binding sites on actin?

Accepted Answer

Binding of Ca$$^{2+} to $$troponin

Question 4

A muscle fiber is stimulated by a motor neuron. Which sequence correctly describes the events leading to contraction?

Accepted Answer

ACh release → Action potential → Ca$$^{2+}$$ release → Sarcomere shortening

Question 5

Which equation best represents the Na$$^+/K$^+$$ pump activity in maintaining resting membrane potential?

Accepted Answer

$$3	ext{Na}^+ 	ext{out} : 2	ext{K}^+ 	ext{in}$$

Question 6

If a muscle fiber is at rest and its sarcolemma is polarized at $$-85	ext{mV}$$, what must occur for an action potential to be generated?

Accepted Answer

The membrane potential must reach threshold at $$-55	ext{mV}$$

Question 7

Which protein prevents myosin from binding to actin in a resting muscle fiber?

Accepted Answer

Tropomyosin

Question 8

What is the effect of botulinum toxin (botulism) on skeletal muscle function?

Accepted Answer

It blocks ACh release, causing paralysis

Question 9

Which phase of a muscle twitch involves Ca$$^{2+}$$ binding to troponin and cross-bridge cycling?

Accepted Answer

Contraction phase

Question 10

A muscle fiber is repeatedly stimulated before it fully relaxes, resulting in increasing tension. What is this phenomenon called?

Accepted Answer

Wave summation

Question 11

Which type of muscle contraction occurs when tension exceeds the load and the muscle shortens?

Accepted Answer

Concentric contraction

Question 12

During peak muscle activity, which metabolic pathway is primarily used to generate ATP, and what is a major byproduct?

Accepted Answer

Glycolysis; lactic acid

Question 13

Which muscle fiber type is most resistant to fatigue and contains high levels of myoglobin?

Accepted Answer

Slow fibers

Question 14

What is the role of creatine phosphate in muscle cells?

Accepted Answer

It converts ADP to ATP during high demand

Question 15

Which clinical condition is characterized by progressive loss of ACh receptors at the neuromuscular junction?

Accepted Answer

Myasthenia gravis

Question 16

If a muscle fiber is stimulated at a frequency that eliminates the relaxation phase, resulting in continuous contraction, what is this called?

Accepted Answer

Complete tetanus

Question 17

Which equation represents the net ATP yield from aerobic cellular respiration of one glucose molecule?

Accepted Answer

$$	ext{Glucose} + 6	ext{O}_2 ightarrow 6	ext{CO}_2 + 6	ext{H}_2	ext{O} + 36	ext{ATP}$$

Question 18

Which structure is responsible for transmitting the action potential deep into the muscle fiber?

Accepted Answer

T-tubules

Question 19

In the Cori cycle, what happens to lactate produced by muscle cells during intense activity?

Accepted Answer

It is absorbed by the liver and converted to pyruvate

Question 20

Which term describes the fixed end of a muscle, where it attaches to bone?

Accepted Answer

Origin

Skeletal Muscle Tissue and the Muscular System: Structure, Function, and Physiology

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