Chapter 5 (B)

25問 • 1年前

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The necessary calcium required for a muscle contraction is provided by:

The sarcoplasmic reticulum, The transverse tubules (T system)

In order to induce muscle contraction, calcium is bound to:

Troponin – at certain binding sites

Which of the following substances are involved in the contraction of the striated skeletal muscle?:

Actin – myosin, Myoglobin – myosin

Muscle relaxation:

Takes place when there are no more nerve impulses to stimulate the muscle, Requires the pumping of calcium into the terminal cisternae, Takes place by reverting troponin to its resting configuration, which causes tropomyosin to cover the sites where myosin binds to actin filaments

During muscle relaxation:

Calcium ions are actively transported into the T tubules and the sarcoplasmic reticulum, Cross bridges between actin and myosin filaments are broken

During muscle contraction:

Acetylcholine crosses the synaptic cleft at the neuromuscular junction, The sarcomere becomes shorter, Cross bridges between actin and myosin filaments are formed

The motor unit:

May contain a variable number of muscle fibres, Is represented by a motor neuron together with all the muscle fibres which it stimulates

Unlike smooth muscle fibres, striated muscle fibres contain:

Sarcomeres, Striations, Troponin

Adenosine triphosphate in muscle cells:

Is decomposed by enzymes into adenosine diphosphate and an inorganic phosphate group, Is necessary for the relaxation of the muscle fibre, Represents a limited reserve which has to be constantly regenerated

Choose the correct statement(s) from below:

The muscle’s sustained maximal contraction is called tetanus, Muscle tone is the muscle’s partial contraction, maintained over a long period of time

The energy used for muscle contraction:

Derives from adenosine triphosphate which will be decomposed by enzymes under the action of ATP-ase, Is produced by the mitochondria where reactions of the process of cellular respiration take place, Derives from carbohydrate metabolism when ATP (adenosine triphosphate) and phosphocreatine reserves have been exhausted

Lactic acid is produced as a result of:

Prolonged anaerobic cellular processes which induce pyruvic acid conversion, The conversion of pyruvic acid when the cell’s oxygen reserve has been exhausted

Which of the following statements below referring to the organic substances in muscles is/are correct?:

Myoglobin is the pigment which binds oxygen molecules and temporarily stores them in the muscle, Myosin filaments have golf-club-shaped endings oriented laterally

ATP-ase:

Is an enzyme found at the ends of myosin filaments, Degrades ATP (adenosine triphosphate) into ADP (adenosine diphosphate) and a phosphate group, releasing energy from the molecule

Phosphocreatine:

Represent a cellular energy deposit, containing high-energy phosphate bonds, Transfers a phosphate group to an ADP (adenosine diphosphate) molecule in order to regenerate an ATP (adenosine triphosphate) molecule

The following statement(s) is/are true about myoglobin:

It binds oxygen molecules and stores them temporarily in the muscles, Its presence in the muscle fibre decreases the necessity of a constant oxygen supply to the muscle during contraction

The smooth muscle tissue:

Does not have striations, Is present in the walls of certain viscera (stomach, uterus, rectum), Contains cells interconnected by collagen fibres and sometimes by gap junctions

Smooth muscle cells are interconnected by:

Elastin and collagen fibres, Collagen fibres and sometimes by gap junctions

The fibres of the unitary smooth muscle:

Contract rhythmically, like a unit, Are interconnected by gap junctions, Are not present in the wall of the airways

The fibres of the multi unitary smooth muscle:

Contain few gap junctions, Form the hair erector muscles, Are present in the wall of large arteries

The following statement(s) is/are true referring to cardiac muscle cells:

They are ramified, shorter and wider than striated skeletal cells, They are interconnected by gap junctions and by desmosomes, They often branch out forming a real network with the neighbouring cells

The following statement(s) is/are true about the structure of the skeletal muscle fibre:

The repetitive distribution of sarcomeres gives the muscle its characteristic striated aspect, The clear bands, called I bands, are wide and contain actin, Thin filaments consist of actin (contractile protein in the structure of myofibrils)

Muscle fibres contain:

Proteins – myosin, troponin, actin in the striated muscle, Protein – calmodulin, in the smooth muscle

Striated skeletal muscles:

Is inserted on bones, the muscle – bone unit ensuring the movements of the body and its various segments, Are responsible for the complex act of locomotion, Can act by triggering body part movements in opposite directions, when they are antagonistic muscles

Choose the true statement(s) from below:

Adenosine triphosphate acid (ATP) regenerates during muscle contraction due to the energy released by anaerobic glycolysis (two ATP molecules/mol of split glucose), Phosphocreatine decomposition regenerates ATP (adenosine triphosphate), when the latter is exhausted

Chapter 1 (komplett)

X · 50問 · 1年前

Chapter 1 (komplett)

50問 • 1年前

Chapter 1 (A)