Question 1

Smooth muscle is regulated by all of the following except

Accepted Answer

The somatic nervous system does not regulate smooth muscle. It is responsible for voluntary control of skeletal muscle. The autonomic nervous system, neurotransmitters, hormones, and prostaglandins all can regulate smooth muscle.

Question 2

In smooth muscle,cross-bridging occurs due to

Accepted Answer

In smooth muscle, calcium binds to calmodulin, which then activates myosin light chain kinase (MLCK). MLCK phosphorylates myosin heads, allowing cross-bridge cycling to occur.

Question 3

Smooth muscle

Accepted Answer

Smooth muscle depolarizes when both sodium and calcium ions diffuse into the cell, which is different from skeletal muscle that primarily relies on sodium ions for depolarization.

Question 4

The type of neurotransmitter or hormone that binds to receptors on smooth muscle plasma membranes determines the response of the muscle.

Accepted Answer

The answer of The type of neurotransmitter or hormone that...

Question 5

Maureen is hiking in the cold,and to maintain homeostasis her body begins to

Accepted Answer

When Maureen is hiking in the cold, her body will shiver in order to generate heat to maintain homeostasis. Shivering is a quick and effective way to increase heat production in the muscles, which can compensate for the heat lost to the environment. Option A is incorrect because increasing heat loss from the skin would further reduce internal body temperature and would not help to maintain homeostasis in the cold. Option B is incorrect because releasing chemicals to initiate a high fever is not a normal response to cold temperatures. Option D is incorrect because reducing blood pressure is not a typical response to cold temperatures and would not help to maintain homeostasis. Option E is incorrect because vasodilating vessels in the head and neck would not contribute to heat production or conservation.

Question 6

Myosin phosphatase

Accepted Answer

Myosin phosphatase removes phosphate from myosin, allowing for muscle relaxation by decreasing myosin-actin interaction.

Question 7

The diffusion of calcium ions into a smooth muscle cell does not depolarize the membrane so no action potential occurs.

Accepted Answer

The diffusion of calcium ions into a smooth muscle cell does not directly depolarize the membrane and lead to an action potential. Instead, it initiates a series of intracellular events that cause the smooth muscle to contract.

Question 8

Multiunit smooth muscle is located in the

Accepted Answer

The answer of Multiunit smooth muscle is located in the
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Question 9

Functionally,smooth muscle

Accepted Answer

Smooth muscle exhibits autorhythmic contractions, meaning it can contract rhythmically and independently of external stimuli, which is crucial for functions like peristalsis in the digestive tract.

Question 10

Which of the following is NOT true of the latch state of smooth muscle contraction?

Accepted Answer

The latch state occurs when the phosphate is removed from myosin while the cross-bridges are not attached to actin. This allows the smooth muscle to maintain tension without expending a lot of energy for longer periods of time. The other options (A, B, C, E) are all true statements regarding the latch state of smooth muscle contraction.

Question 11

Betsy took a fall,broke her arm,and when she took the cast off she was alarmed to see that her muscles

Accepted Answer

When a limb is immobilized in a cast or brace, the lack of physical activity can lead to muscle disuse, which in turn causes muscle atrophy. Therefore, it is likely that Betsy's muscles had undergone atrophy after the cast was removed.

Question 12

Susan slipped on the ice and was unable to be fully mobile for several days.What disruption to homeostasis would you predict she experienced during her immobile period in terms of her muscular system?

Accepted Answer

Inactivity prevents muscles from generating heat, which can lead to feeling colder than usual. A and C are not relevant to the disruption of homeostasis in the muscular system caused by immobility.

Question 13

In a laboratory experiment,the resting membrane potential of a muscle is measured and is found to be more negative.Which of the following has occurred?

Accepted Answer

Hyperpolarization occurs when the resting membrane potential becomes more negative. This is due to an increase in the permeability of the membrane to potassium ions or a decrease in the permeability to sodium ions, causing an increase in the outward movement of potassium ions or a decrease in the inward movement of sodium ions, respectively.

Question 14

In smooth muscle,most of the calcium needed for muscle contraction

Accepted Answer

In smooth muscle, most of the calcium needed for muscle contraction enters from the extracellular fluid. This is different from skeletal muscle, where the calcium is released from the sarcoplasmic reticulum.

Question 15

Which of the following statements concerning smooth muscle is true?

Accepted Answer

Smooth muscle contraction is initiated by the binding of calcium ions to the protein calmodulin, which then activates the enzyme myosin light-chain kinase to phosphorylate myosin, allowing for actin-myosin cross-bridge formation. Smooth muscle does not contain sarcomeres like striated muscle and does not have a well-developed sarcoplasmic reticulum for calcium storage and release. Smooth muscle cells are also typically small and uninucleated, unlike the large and multinucleated cells of skeletal muscle.

Question 16

What are caveolae?

Accepted Answer

Caveolae are shallow invaginations or indentations of the cell membrane that are involved in various cellular functions such as endocytosis and signal transduction. They are typically found in cells that specialize in transporting molecules across the cell membrane, such as endothelial cells and muscle cells.

Question 17

Select the term that does not belong with the others.

Accepted Answer

The first four choices (muscle atrophy, immobilization, decrease in number of myofibrils, loss of nerve stimulation) all contribute to a decrease in muscle size or strength, while increased vascularity refers to an increase in blood vessels in the muscle tissue.

Question 18

When comparing smooth and skeletal muscle cells,which of the following statements is true?

Accepted Answer

Smooth muscle cells do not have striations because the myofilaments are not arranged in sarcomeres as they are in skeletal muscle cells. Smooth muscle cells are also typically smaller than skeletal muscle cells and are not multinucleated. However, smooth muscle does have a significant amount of actin and myosin.

Question 19

An antibody test on smooth muscle reveals fewer dense bodies and intermediate filaments in a patient with a colon disorder.What is the purpose of these structures?

Accepted Answer

Dense bodies and intermediate filaments are important components of the intracellular cytoskeleton in smooth muscle cells. They provide structural support to maintain the shape and integrity of the cell, and also facilitate muscle contraction by linking the actin and myosin filaments in the cell. Therefore, a decrease in these structures could affect the function of the smooth muscle and potentially contribute to the colon disorder observed in the patient.

Question 20

Visceral smooth muscle

Accepted Answer

The answer of Visceral smooth muscle
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Quiz 9: Muscular System: Histology and Physiology