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7/31/2019 Mcq Physio

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AIDS

2012CARDIAC PROPERTIES AND ECG

qUESTIONS


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1. All of the following are true about myocardial

rhythmicity EXCEPT

a) Is myogenic in nature

b) Is the ability of the cardiac muscle to generate action

potential spontaneously and regularly

c) Ectopic pacemaker possesses the greatest rhythmicity

and initiate beat of the whole heart

a) A-V nodal rhythm produce slower heart rate


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2. Choose the incorrect pair

A. S-A node - 105 beats /minute

B. A-V node - 45-60 beats /minute

C. Purkinje system - 25-40 beats/minute

D. Idioventricular rhythm - 30-50 beats/minute


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3. Which of the following is FALSE regarding the factors

affecting myocardial rhythmicity ?

I. Whole heart is innervated by vagus nerve and sympatheticnervous system except ventricle

II. S-A node discharges spontaneously at a rate about 105

impulse/minute intrinsic heart rate

III. Myocardial rhythmicity increase with increase in body

temperature

IV. Excess of calcium can increase the diastole until the heart

stops in diastole

a) I and II

b) II and III

c) III and IV

d) I, II and IV


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4. All of the following is INCORRECT about conductivity of

the heart EXCEPT

a) Physiologically, A-V node has very long relative refractory

period

b) A-V node protect the ventricle from pathological

hyperactivity of atria

c) Rapid impulse conduction through purkinjes fiber because

this fiber has many fascia adherens and gap junction

d) A-V node is large in size and its intercalated disc

contain less gap junction


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5.

S-A node A-V node bundle of His bundle branches

terminal purkinjes fiber

Which of the following physiological properties of the heart

describe the flow above.

A. Rhythmicity

B. Conductivity

C. Excitability

D. Contractility

.


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1) Mention three excitability changes during cardiac

activity.

Discuss about the changes.

Absolute refractory Period

Relative refractory period

Supernormal phase


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Absolute refractory period

-During this period, cardiac muscle shows complete loss of

excitability(complete depolarization)-no other stimulus whatever strong can exite it

-this period occupies whole systole and the early part of diastole

-prevent occurence of tetanus in the heart

Relative refractoty period

-excitability gradually recovers until it reaches the normal value.

Supernormal phase

-excitability is more than 100%. A weaker stimulus is needed

to excite and a stronger contraction is produced.


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2) Discuss about Frank-Starling law of the heart

Autoregulation of cardiac pumping.


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The law states that

The strength of cardiac contraction is directly proportional to the

initial length of its fiber(end diastolic volume/preload),

provided the fibers are not excessively stretched above their

elastic limits.

Another way to express the law

Within physiological limits, the heart pumps all the blood comes to

it without allowing excessive stasis of blood in the veins.

This intrinsic ability of the heart to adapt itself itself to changing

venous blood returned to the heart is the basis of

autoregulation of cardiac pumping.


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1. All of the following is true about P wave except :

a. Represents atrial depolarization

b. Duration is 0.2 sec

c. Spread of impulses from SA nodes to AV nodes

d. It's large in case of atrial hypertrophy


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2. Bundle branch block causes

a. Increase in QT interval

b. Increase in time of QRS complex

c. Increase in amplitude of QRS complex

d. Depression of ST segment


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3. Slow repolarization of the papillary muscle isrepresented by :

a. T wave

b. QRS complex

c. P wave

d. U wave


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4. QT interval increases in case of :

a. Hypercalcemia

b. Hypocalcemia

c. Hyperkalemia

d. Hypokalemia


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5. All of the following is true in case of T-wave except :

a) Stage of fast, strong repolarization of the heart ventricles

b) Waves are in same direction to depolarization

of ventricles

a) Waves are positive

b) Flattened in old age


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1) What is ECG?

Record of electric potential fluctuations during the cardiaccycle.


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2) Enumurate the types of bipolar leads and chest

leads.

BIPOLAR LEADS

-Lead I

-Lead II

-Lead IIIUNIPOLAR LEADS

Unipolar limb leads

-aVR

-aVL-aVF

Unipolar Chest Leads

-VI, V2, V3, V4, V5, V6


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3. What is the causes of Q, R and S waves?

Q-depolarization of

inter-ventricular septum which takes place from left to right.

R- depolarization ofventricular muscle from the inner to outer surface.

S- depolarization of

last segment of the myocardium.(posterobasal

portion of the left ventricle and the pulmonary

conus)


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4. ECG with P-R interval 0.4 sec. Is it normal?

Comment on your answer.

It is abnormal.The normal range of P-R interval is from 0.12-0.2 sec.

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