Schwere Fragen

20問 • 1年前

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Choose the correct associations referring to the three types of muscle tissue:

Central single nucleus – smooth muscle tissue, myocardium, Sarcomeres – skeletal striated muscle tissue – cardiac muscle tissue

Choose the true statement(s) referring to the striated skeletal muscle:

Their tubular arrangement consists in two tubes/sarcomeres, located at the A – I junctions, It is controlled by the somatic nervous system

The following statement(s) is/are true about the smooth muscle:

It cytoplasm contains actin and myosin filaments, forming similar structures to that of microfibrils, The contraction of the rectum wall muscle contributes to the elimination of the rectal content, It has diffuse junctions where neurotransmitters are released

The microscopic aspect of the sarcomere shows:

The presence of two types of myofilaments (actin and myosin), arranged parallel to each other, The presence of Z-line – the area in which the actin filaments of two adjacent sarcomeres are interconnected, The clear band divided into two equal halves by the Z-line is called I-band

The following statement(s) is/are true about the microscopic structure of the sarcomere:

Thin actin myofilaments and thick myosin myofilaments are arranged parallel to each other, The A-band is divided into two equal halves by the H zone which contains only myosin filaments, Thick filaments consist of myosin, a protein formed of two polypeptide chains twisted around each other

The actin filament:

Is thin and looks like a helix formed of two polypeptide chains twisted around each other, Contains tropomyosin molecules in the groove of the helix

The following statement(s) is/are true about calcium ions (Ca 2+) in the muscle fibre:

Normally, in a resting cell, their concentration is very low in the sarcoplasm, They are constantly pumped out of or into the cell in the cell’s specialised smooth endoplasmic reticulum (sarcoplasmic reticulum), They are stored in the sarcoplasm reticulum reservoir and on the transverse tubule system (T tubules)

Acetylcholine:

Is released in the synaptic cleft of the neuromuscular junction, Is a neurotransmitter which can also be released by certain neurons in the encephalon, Is bound to the receptors on the cellular membrane of the muscle fibre (sarcolemma)

Muscle contraction requires the following:

Acetylcholine - neurotransmitter, Sodium ions (Na+) which permeate the cell when acetylcholine is bound to the sarcolemma receptors

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

The sarcoplasmic reticulum, The transverse tubules (T system)

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 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

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

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 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)

Chapter 1 (komplett)

X · 50問 · 1年前

Chapter 1 (komplett)

50問 • 1年前

Chapter 1 (A)