問題一覧
1
The following statement(s) is/are true about the muscular tissue:
It is one of the body’s four main tissues (together with the epithelial, connective and nervous tissues), Its structural unit is the muscle cell, also called muscle fibre
2
The muscle tissue will form:
Skeletal striated muscles, The organs responsible for body movements
3
The following types of muscles form the muscular system:
Striated (skeletal) muscles, under voluntary control, Smooth muscles which trigger spontaneous, involuntary contractions, The myocardium (heart muscle) which has involuntary, rhythmical contractions
4
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
5
Choose the statements which describe accurately the differences between the striated skeletal muscle and the cardiac muscle:
They have different locations, the striated skeletal muscle being inserted onto the bones, The striated skeletal muscle fibre is multinucleated, while the cardiac muscle fibre has a single nucleus, The striated skeletal muscle has a much faster contraction speed than the cardiac muscle
6
Choose the true statement(s) referring to the muscle tissue:
It is one of the four main tissues in the body, It has the ability to contract, It has the ability to perform mechanical work, The muscle cell (fibre) is the structural unit of the muscle tissue
7
The shape of muscle fibres in the various types of muscles can be:
Elongated, cylindrical with rounded ends in striated skeletal muscles, Fusiform with sharp ends in smooth muscles
8
The following statement(s) is/are true referring to the smooth muscle:
It can be unitary and multi-unit, The fibres of unitary smooth muscle have gap junctions, The smooth muscle fibre receives nerve impulses from the vegetative (autonomic) nerves
9
The following statement(s) is/are true about the cardiac muscle:
It receives impulses generated by the cells of the excito-conductor system, It is not under voluntary nervous control, It has a striated microscopic aspect
10
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
11
Which of the following statements characterize(s) the cardiac muscle?
It is present only in the structure of the heart (in the heart wall), Its fibres (often ramified) form a real network with adjacent fibres, Intercalated discs facilitate the propagation of contractions from one cell to the other
12
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
13
Which of the following statements is/are characteristic for the structure of the striated skeletal muscle fibre?
Each fibre contains 4-20 filiform filaments with a length up to 100μ, In sarcomeres, myofibrils are organised along their longitudinal axis, The repetitive distribution of sarcomeres gives them their characteristic striated aspect
14
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
15
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
16
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
17
The red muscle:
Contains a large quantity of myoglobin, an oxygen-storing protein, Is a slow or oxidative muscle, It can withstand muscle fatigue, due to the oxygen stored in the myoglobin, which will be used in cellular respiration
18
The white muscle:
Is a fast, glycolytic muscle (so called due to its high glycogen content), Rapidly uses ATP (adenosine triphosphate acid) but it cannot replace it as fast as it uses it, It has very little available oxygen necessary for cellular respiration
19
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)
20
During the greatest muscle contraction in skeletal muscles:
The thin actin filaments are superposed, Sarcomeres reach their smallest size, The H-zone disappeared and the I-band greatly decreased in size
21
Filament sliding cycles in striated muscles:
Take place as long as adenosine triphosphate is available, Take place very quickly, at millions of myosin ends, Take place as long as there is a nerve stimulus
22
Myoglobin:
Is present in large quantities in red muscle fibres, Is the muscle pigment which stores oxygen necessary for cellular respiration
23
A neuromuscular junction consists of:
A single muscle fibre, very close to the nerve ending, but without touching it, The end of a single nerve cell which does not touch the sarcolemma of the muscle fibre, The synaptic cleft – a fluid filled space
24
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)
25
Muscle contraction requires the following:
Acetylcholine - neurotransmitter, Sodium ions (Na+) which permeate the cell when acetylcholine is bound to the sarcolemma receptors
26
The necessary calcium required for a muscle contraction is provided by:
The sarcoplasmic reticulum, The transverse tubules (T system)
27
In order to induce muscle contraction, calcium is bound to:
Troponin – at certain binding sites
28
Which of the following substances are involved in the contraction of the striated skeletal muscle?:
Actin – myosin, Myoglobin – myosin
29
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
30
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
31
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
32
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
33
Unlike smooth muscle fibres, striated muscle fibres contain:
Sarcomeres, Striations, Troponin
34
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
35
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
36
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
37
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
38
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
39
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
40
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
41
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
42
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
43
Smooth muscle cells are interconnected by:
Elastin and collagen fibres, Collagen fibres and sometimes by gap junctions
44
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
45
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
46
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
47
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)
48
Muscle fibres contain:
Proteins – myosin, troponin, actin in the striated muscle, Protein – calmodulin, in the smooth muscle
49
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
50
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