Nerve and muscleA- 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 contractionb- 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.

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-cB- True or false questions:Key answer:1- F – F – F – T 2- T – T – T – F3- T –F – T - F 4- F – T – T – T5- F – T – F – T 6- T – T – F – F7- T – T – F – F 8- F – F – T – T9- F – T – T – T 10- F – T – F – T

11- T – T – F – T 12- F – F – F – T13- T – T – F – F 14- T – T – F – F15- F – F – T - T