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mcq physiology

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mcq physiology Empty mcq physiology

مُساهمة من طرف mido le roi السبت أغسطس 14, 2010 9:11 am

mcq physiology 60774430

mcq physiology Fw12


Nerve and muscle
A- Choose the best answer:
1- Slow axonal transport is important in:
a- Transport of nerve impulse.
b- Renewing the cytoplasm and regenerating the axon.
c- Formation of myelin sheath.
d- Neuro-muscular transmission.
2- About cellular sheath ( sheath of Schwann):
a- The outer layer of Schwann cells is called epi-neurium.
b- Surrounds the axons of all neurons inside and outside the CNS.
c- It is responsible for the color of the white matter of the spinal cord.
d- It is essential for regeneration of the damaged verve fibers.
3- Myelin sheath:
a- Present in the myelinated and unmyelinated nerve fibers.
b- Formed of lipoprotein complex and acts as electric insulator.
c- It is formed of successive wrappings of the membrane of Schwann cells.
d- It is the cause of decreased conduction of nerve impulse.
4- Chronaxia:
a- is the minimal stimulus which produce response after relatively long time.
b- is the minimal time needed by the strong stimulus to produce response.
c- is the time required to stimulate the nerve by a minimal stimulus.
d- is the time required to stimulate the nerve by a stimulus which is double rheobase.
5- During depolarization:
a- voltage activated Na+ channels open.
b- the membrane becomes impermeable to Na+.
c- when the membrane potential reaches -55 m.v Na+& K+. channels open at the same time.
d- K+ ions diffuse outside.
6- The resting membrane potential is caused by:
a- Diffusion of K+ ions outside the nerve fibers.
b- Diffusion of Na+ ions inside the nerve fibers.
c- Opening of the chemically activated ion channels.
d- Opening of the voltage activated ion channels.
7- To measure resting membrane potential:
a- We use a special voltmeter or CRO.
b- We put the two electrodes outside the nerve fiber.
c- We stimulate the nerve by an effective stimulus.
d- We put the two electrodes inside the nerve fiber.
8- Repolarization:
a- Occurs at first gradual then becomes fast.
b- Results from closure of sodium gates and opening of potassium gates.
c- is represented by the ascending limb of the spike.
d- is followed by appearance of response.
9- Continuous conduction:
a- occurs in myelinated nerve fibers.
b- occurs by jumping of charges from one node of Ranvier to another.
c- is relatively slow 0.5-2.0 meter / second.
d- occurs in the neuro-muscular junction.
10- Saltatory conduction:
a- occurs in unmyelinated nerve fibers.
b- may reach up to 120 meter / second.
c- occurs by jumping from one neuron to another.
d- decreases gradually with distance till it disappears.
11- In biphasic action potential:
a- One electrode is put inside and the other is put outside the same nerve fiber.
b- The two electrodes are put outside the nerve.
c- Deflection occurs in one side only.
d- Anelectrotonus occurs at the anode and catelectrotonus occurs at the cathode.
12- In monophasic action potential :
a- One electrode is put inside and the other is put outside the same nerve fiber.
b- The spike is a large wave of short duration.
c- The spike is followed by positive after potential then negative after potential.
d- The ascending limb of the spike is due to K+ outflux.
13- Local excitatory state is characterized by the following except:
a- its magnitude is directly proportional with the intensity of the sub-minimal stimulus.
b- does not obey all or non rule.
c- can be summated.
d- propagated without decrement.
14- About A fibers all are true except:
a- They have the greatest diameter.
b- They conduct impulses with the greatest velocity (10-120 met./sec)
c- They include somatic sensory and motor fibers.
d- They are very sensitive to local anesthetic drugs.
15- In all or non rule:
a- A minimal stimulus produces a maximal response.
b- The response in a single nerve fiber increases with increase intensity of stimulus.
c- The nerve trunk either respond maximally or not respond at all.
d- Minimal stimulus produces minimal response.
16- Excitation contraction coupling involves all the following except:
a- Release of Ca++ from troponin.
b- Formation of cross bridges between actin and myosin.
c- Spread of depolarization along the transverse tubules.
d- Hydrolysis of ATP to ADP.
17- Muscle fatigue is due to:
a- Inability of the action potential to spread over the muscle.
b- Failure of transmission in the motor nerve.
c- Failure of neuro-muscular transmission.
d- Depletion of energy stores.
18- Anelectrotonus :
a- is a localized area of depolarization .
b- results from stimulation by effective galvanic current .
c- is associated with decreased excitability .
d- used to stimulate the nerve fibers .
19- Nerve block is produced by:
a- Sever cooling.
b- Strong catelectrotonus.
c- Decrease Ca++ ions.
d- Increased Na+ ions .
20- Which of the following has the lowest conduction velocity:
a- A α fibers.
b- A β fibers.
c- B fibers.
d- C fibers.
21- The action potential of skeletal muscle:
a- has a prolonged plateau phase.
b- spread inward to all parts of the muscle via T tubules.
c- is longer than the action potential in the cardiac muscle.
d- cause re-uptake of Ca++ into the terminal cisternae.
22- The function of tropomyosin in skeletal muscle include:
a- binding to myosin during contraction
b- acting as a relaxing protein at rest by covering the binding sites on actin.
c- sliding on actin to produce shortening.
d- releasing Ca++ after propagation of action potential.
23- Cross bridges of sarcomere in skeletal muscle are made up of:
a- Actin.
b- Troponin.
c- Tropomyosin.
d- Myosin.
24- Contraction of skeletal muscles:
a- produces more work when the muscle contracts isometrically than when the muscle contracts isotonically.
b- depends on external Ca++.
c- decrease in magnitude with rapid repeated stimulation.
d- does not depend on action potential.
25- The action potential in a nerve fiber:
a- results in a transient reversal of polarity of the membrane potential.
b- is terminated by the influx of K+.
c- is initiated by the efflux Na+.
d- declines in magnitude as it moves along the nerve fiber.
26- The motor end plate potential is produced by:
a- opening of Na+ channels.
b- opening of Na+ channels then opening of K+ channels.
c- opening of Na+ and K+ channels at the same time.
d- opening of Ca++ channels.
27- Nerve block is produced by all the following except:
a- local anesthetics.
b- excessive cooling.
c- deep pressure.
d- strong catelectrotonus.
28- As regard neuro-muscular transmission all are true except:
a- it shows fatigue due to depletion of acetyl choline vesicles.
b- occurs from nerve to muscle i.e. one way conduction.
c- it is stimulated by succenyl choline.
d- it is blocked by botulinum toxins.
29- Red ( slow ) fibers are characterized by the following except:
a- contains much blood capillaries.
b- glycogen stores is low.
c- contains high concentration of myoglobin.
d- depends on anaerobic oxidation.
30- As regard sarcomere all are true except:
a- It is the distance between 2 Z membranes.
b- It is shortened during contraction.
c- The width of the I band does not change during contraction.
d- The width of the A band does not change during contraction.
31- As regard transverse tubules all are true except:
a- it increases the surface area of the cell membrane.
b- it transmits action potential to inside the fiber.
c- it acts as a Ca++ stores.
d- it is absent in smooth muscle fibers.



mcq physiology Fw12

B- True or false questions:
1- Neuromuscular transmission is blocked by :
a- prostigmine .
b- increase Ca++ ions.
c- acetylcholine .
d- succinylcholine .
2- A property shared by :
a- Skeletal and cardiac muscle is their striated appearance.
b- Cardiac and visceral smooth muscles is their spontaneous activity when denervated.
c- All muscles is that contraction strength is related to their initial length.
d- Cardiac and skeletal muscles obey all or non rule.
3- Visceral smooth muscle differs from skeletal muscle in that:
a- It contracts when stretched.
b- It contains no actin or myosin.
c- Its cells have unstable resting membrane potential.
d- It is not paralyzed when its motor nerve is cut.
4- The Sarcomere:
a- is the distance between myosin and actin.
b- is the distance between two Z membranes.
c- is the contractile unite of the muscle.
d- shorten when the muscle contracts .
5- Excitability of nerve fibers :
a- is increased by decreased temperature.
b- is increased by increased Na+.
c- decreased by decrease Ca++ ions.
d- is completely lost by local anesthetic drugs .
6- The energy of muscle contraction is derived from:
a- ATP and creatin phosphate.
b- muscle glycogen.
c- lactic acid.
d- ADP and cyclic AMP.
7- Contraction of smooth muscles:
a- is increased by increased Ca++.
b- is decreased by cooling.
c- is increased by excessive stretch.
d- is decreased by hypotonic solutions.
8- Smooth muscles:
a- is innervated by the somatic nervous system.
b- their denervation leads to paralysis.
c- have double nerve supply.
d- some fibers receive single nerve supply.
9- As regards contraction of smooth muscle fibers:
a- Ca++ influx is induced by activation of voltage gated Ca++ channels only.
b- myosin phosphatase is essential for relaxation.
c- relaxation occurs by decrease of intracellular Ca++ concentration.
d- extra-cellular Ca++ plays an essential role.
10- The frequency needed to produce tetanus :
a- is increased by cooling.
b- is decreased in red muscles.
c- is increased fatigue.
d- is decreased by anti-choline estrases.
11-Depolarization:
a- is associated with increase in membrane permeability to Na+.
b- is terminated with closure of voltage activated Na+ channels.
c- the membrane potential is moving away from zero potential.
d- refers to an increase in membrane potential.
12- Action potentials:
a- are graded electric potentials.
b- are produced by sub threshold stimuli.
c- are associated with repolarization phase caused by outward movement of Cl-.
d- are conducted over the surface of the excitable membranes.
13- RMP of a nerve:
a- is caused by unequal distribution of ions along both sides of the membrane.
b- is caused by selective permeability of the membrane to the ions.
c- Na+ - K+ pump has no role in RMP.
d- is caused by inward movement of Na+ ions.
14- As regard conduction of action potential in a nerve:
a- in thick myelinated nerve fibers can reach up to 120 meter / second.
b- can be inhibited by hyper-calcemia.
c- can be increased by cooling.
d- it is conducted with decrement.
15- Pale ( fast) fiber:
a- contains much blood capillaries.
b- doesn't show fatigue.
c- contains low concentration of myoglobin.
d- depends on anaerobic oxidation.

A- Choose the best answer:
Key answer:
1-b 2-d 3-b 4-d 5-a 6-a 7-a 8-b 9-c
10-b 11-b 12-b 13-d 14-d 15-a 16-a 17-d 18-c 19-a 20-d 21-b 22-b 23- d
24-c 25-a 26-c 27-d 28-c 29-d 30-c 31-c
B- True or false questions:
Key answer:
1- F – F – F – T 2- T – T – T – F
3- T –F – T - F 4- F – T – T – T
5- F – T – F – T 6- T – T – F – F
7- T – T – F – F 8- F – F – T – T
9- F – T – T – T 10- F – T – F – T
11- T – T – F – T 12- F – F – F – T
13- T – T – F – F 14- T – T – F – F
15- F – F – T - T


mcq physiology Fw12
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mido le roi
mido le roi
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عدد المشاركات : 1407
تاريخ التسجيل : 26/07/2010
المود : mcq physiology Stressed
mcq physiology 4thyea10

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