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Question 1
Incorrect
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Calcium needed for cardiac muscle contraction is made available during which phase of the action potential?
Your Answer: 4
Correct Answer: 2
Explanation:It is made available during the plateau phase of the action potential i.e. phase 2. During the plateau phase of the action potential, Calcium from the extracellular fluid enters through the L type of calcium channels. This entry triggers the release of more calcium from the sarcoplasmic reticulum via the ryanodine receptors.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 2
Incorrect
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When the heart rate is increased (to pathological levels) which of the following is correct when comparing the duration of diastole to systole?
Your Answer: It is lengthened to a greater degree
Correct Answer: It is shortened to a greater degree
Explanation:The duration of systole is more fixed than the duration of diastole. When the heart rate increases the timing of the systole remains more or less the same however diastole decreases.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 3
Incorrect
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Water hammer pulse is found in:
Your Answer:
Correct Answer: Aortic insufficiency
Explanation:Watson’s water hammer pulse is the medical sign which describes a pulse that is bounding and forceful, rapidly increasing and subsequently collapsing, as if it were the sound of a water hammer that was causing the pulse. A water hammer was a Victorian toy in which a tube was half filled with fluid, the remainder being a vacuum. The child would invert and reinvert the tube; each time the impact of the fluid at each end would sound like a hammer blow. This is associated with increased stroke volume of the left ventricle and decrease in the peripheral resistance leading to the widened pulse pressure of aortic regurgitation.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 4
Incorrect
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Question 5
Incorrect
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During exercise, a man consumes 2L O2/min, his arterial 02 content is 190 ml/l and the 02 content of his mixed venous blood is 130ml/l. His cardiac output is approximately:
Your Answer:
Correct Answer: 33l/min
Explanation:In Fick’s original method, the following variables are measured:VO2, oxygen consumption in ml of pure gaseous oxygen per minute. This may be measured using a spirometer within a closed rebreathing circuit incorporating a CO2 absorberCa, the oxygen concentration of blood taken from the pulmonary vein (representing oxygenated blood)Cv, the oxygen concentration of blood from an intravenous cannula (representing deoxygenated blood)From these values, we know that:VO2 = (CO x Ca) – (CO x Cv)where CO = Cardiac Output, Ca = Oxygen concentration of arterial blood and Cv = Oxygen concentration of mixed venous blood.This allows us to sayCO = VO2/{Ca – Cv}and hence calculate cardiac output.Therefore CO = 2/(0.190-0.130) = 33l/minNote that (Ca – Cv) is also known as the arteriovenous oxygen difference.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 6
Incorrect
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Which statement about the 2nd heart sound is true?
Your Answer:
Correct Answer: It is caused by closure of the aortic and pulmonary valves.
Explanation:The second heart sound is produced due to closure of the aortic and pulmonary valves. It is a high pitched dub sound.
Normally the aortic closure sound (A2) occurs prior to the pulmonic closure sound (P2), and the interval between the two (splitting) widens on inspiration and narrows on expiration. With quiet respiration, A2 will normally precede P2 by 0.02 to 0.08 second (mean, 0.03 to 0.04 sec) with inspiration. In younger subjects inspiratory splitting averages 0.04 to 0.05 second during quiet respiration. With expiration, A2 and P2 may be superimposed and are rarely split as much as 0.04 second. If the second sound is split by greater than 0.04 second on expiration, it is usually abnormal. Therefore, the presence of audible splitting during expiration (i.e., the ability to hear two distinct sounds during expiration) is of greater significance at the bedside in identifying underlying cardiac pathology than is the absolute inspiratory increase in the A2–P2 interval.
The respiratory variation of the second heart sound can be categorized as follows: (1) normal (physiologic) splitting; (2) persistent (audible expiratory) splitting, with normal respiratory variation; (3) persistent splitting without respiratory variation (fixed splitting); and (4) reversed (paradoxical) splitting.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 7
Incorrect
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The process by which depolarization of the muscle fiber initiates contraction is called?
Your Answer:
Correct Answer: Action potential
Explanation:This process is known as an action potential. Upon generation of an action potential when depolarization reaches threshold, it spreads throughout the muscle fiber, resulting in generation of an excitation-contraction coupling leading to contraction of the muscle.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 8
Incorrect
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The branche(s) of the left coronary artery include:
Your Answer:
Correct Answer: Left circumflex artery & anterior interventricular artery
Explanation:The left main coronary divides into branches:
1. The left anterior descending artery branches off the left coronary artery and supplies blood to the front of the left side of the heart.
2. The circumflex artery branches off the left coronary artery and encircles the heart muscle.
The anterior interventricular artery is otherwise known as the anterior descending branch. The posterior descending artery comes from Right coronary artery.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 9
Incorrect
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The following are examples of the functions of the vascular endothelium except:
Your Answer:
Correct Answer: Tumour suppression
Explanation:Vascular endothelium has many important functions including regulation of vascular tone, molecular exchange between blood and tissue compartments, hemostasis and signaling for the immune regulation and inflammation. Depending on specific tissue needs and local stresses, endothelial cells are capable of evoking either antithrombotic or prothrombotic events. Tumor suppression is related to genes, or anti-oncogenes, that regulate a cell during cell division and replication.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 10
Incorrect
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Angina pectoris develops when blood through the coronary artery becomes:
Your Answer:
Correct Answer: Restricted, limiting blood blow
Explanation:Angina pectoris develops when stenosis ( >70%) of the artery occurs as a result of formation of an atherosclerotic plaque. This leads to a decrease in the O2 carried to the thickened heart muscle by the blood, leading to the characteristic chest pain associated with angina pectoris.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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SESSION STATS - PERFORMANCE PER SPECIALTY
