Excitable Tissues Worksheet With Answers

 

Excitable tissues MCQ

Dr. Atef Abood

Excitable tissues worksheet Choose the most correct single answer 1.  Which type of K  channels share in resting membrane potential generation? +

a.  Leakage channel b.  Voltage gated channel c.  Calcium gated channels d.  Non selective ion channel 2.  What is the main cation present intracellulary? a.  K+ b.  Na+ c.  Ca++ d.  Mg++

 

3. Which part of the neuron initiates the action potential? a.  Dendrites b.  Axon hillock c.  Cell body d.  Axon terminal 4.  Resting membrane potential is created by all of the following membrane  membrane   characteristics EXCEPT a.  High permeability to K+ b.  Low permeability to Na+ c.  High permeability to proteins d.  Opening of voltage gated sodium channels 5.  In a cell membrane with resting membrane membrane potential -60. If this potential  potential  becomes -90 there will be a.  Depolarization of 30 mv amplitude b.  Hyperpolarizatio Hyperpolarization n with 30 mv amplitude c.  Local excitatory state d.  Generation of action potential with subthreshold stimulus

 

Excitable tissues MCQ

Dr. Atef Abood

6.  If three stimuli are simultaneously applied to a neuron and each one produces a depolarization of 10 mv amplitude which of the following is most likely to occur a.  There will be local potential of 10 mv at the axon hillock b.  Action potential is generated by each stimulus c.  Summation of depolarization

d.  Less probability of production of action potential 7.  Conduction of action potential in neurons a.  Is inversly proportional to membrane diameter b.  Is saltatory in C type c.  Is economic if the nerve is myelinated d.  Very slow in type A fibers

8.  The events at the neuromuscular junction include a.  Opening of volt sensitive calcium channels at the motor end plate b.  Opening of Acetylcholine gated channels at the nerve terminals c.  Binding of acetylcholine to calcium channels d.  Release of acetylcholine neurotransmitter neurotransmitter 9.  Cholinestrase enzyme present at the neuromuscular junction a.  Degrades the peptide bond in the acetylcholine b.  Inhibited by neostigmine c.  Irreversible inhibition inhibition leads to toxicity

 

d. Is not essential in neuromuscular transmission 10. The functional unit of muscle contraction is a.  Single muscle cell b.  Multiple muscle cell c.  The whole muscle d.  Motor unit 11. The DHP receptors a.  Present on the sarcoplasmic membrane b.  Present on the cisternae of sarcoplasmic reticulum c.  IS a voltage gated calcium channels

 

Excitable tissues MCQ

Dr. Atef Abood

d.  Act as a sensor to open calcium channels in the cisternae 12. The calcium released from sarcoplasmic reticulum starts contraction by binding to a.  Troponin I b.  Troponin T c.  Troponin C

d.  Tropomyosin 13. Striated feature of skeletal muscle is due to a.  Presence of alternating dark and light bands b.  Presence of large amount of mitochondria c.  Is present only during muscle contraction d.  Disappears during muscle relaxation 14. Sarcomere a.  Is the functiona and structural unit of mucle cells b.  Is the distance between 2 H zones c.  Shortens during relaxation d.  Has a maximum length at which contraction is maximum

15. The binding of myosin head to actin requires all the following EXCEPT a.  Binding of ca  to troponin C ++

b.  Binding of ATP to myosin head c.  Release of ADP and P from myosin head

 

d. Uncovering of actin binding site 16. Isometric contraction is characterized by a.  Development of no tensin b.  Shortening of the whole muscle c.  Shortening of elastic element d.  Constant length of the muscle 17. In fast glyolytic fibers a.  Energy is derived from oxidation of glucose b.  Rich in hemoglobin c.  Large amount of mitochondria

 

Excitable tissues MCQ

d.  Lactic acid is easily accumulated 18. Starling law relate a.  Musc;e tension tension during contraction contraction to Muslce length b.  Muscle tenstion to number of mitochondria c.  Velocity of contraction to muscle length d.  Muscle tenstion to hormone adrenaline 19. In glycolytic type of muscle fibers a.  Fitigue is less common b.  Mitochodria are abundant c.  Lactic acid acumlates d.  Atpase activity is slow 20. Fatigue in neuromuscular junction is due to a.  Accumulation of lactic acid b.  Depletion of Acetylcholine c.  Exhaution of brain centers d.  Depletion of glycogen stores

Dr. Atef Abood