-
Question 1
Correct
-
The bradycardia that occurs in patients with raised intracranial pressure is a result of the?
Your Answer: Cushing reflex
Explanation:When intracranial pressure is increased, the blood supply to RVLM neurons is compromised. This results in an increase in their discharge as a result of hypoxia and hypercapnia. The resultant rise in systemic arterial pressure (Cushing reflex) tends to restore the blood flow to the medulla.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 2
Correct
-
A sarcomere is the area between:
Your Answer: Two adjacent z lines
Explanation:The area that lies between the two adjacent Z lines is known as a sarcomere and is the contractile unit of the muscle. The line passing in the middle of the myosin filaments is the M line. It also passes through the middle of the sarcomere.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 3
Incorrect
-
Arterioles stemming from the coronary artery can also empty into the heart directly via the:
Your Answer: All arterioles empty into the coronary sinus or anterior cardiac vein
Correct Answer: Arteriosinusoidal vessels
Explanation:Most of the venous blood returns to the heart via the coronary sinus and the anterior cardiac veins. Apart from these there are other vessels that drain directly into the heart chambers. They include arteriosinusoidal vessels, which connect the arterioles to the heart chambers. The thebesian veins drain the capillaries into the chambers and the arterioluminal vessels drain small arteries directly into the chambers.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 4
Correct
-
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: 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 5
Incorrect
-
Direct conduction from the atrium to the ventricles is prevented by:
Your Answer: Bundle of his
Correct Answer: Annulus fibrosus
Explanation:The annulus fibrosus disconnects the syncytium complex. The atria are rapidly activated however the activation peters out when the insulating layer-the annulus fibrosus-is reached.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 6
Correct
-
Blood flow to the subendocardial portions of the left ventricular muscle occurs mainly during:
Your Answer: Diastole
Explanation:The sub endocardium receives the least amount of blood from the coronary arteries. During systole the coronary arteries collapse as a result of the pressure from contraction that is exerted on them. During diastole the heart muscle relaxes and the pressure on the coronary vessels is relieved allowing blood to flow through them to the sub endocardium.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 7
Incorrect
-
Regarding cardiac output, an increased ejection fraction results from increases in which of the following?
Your Answer: Strength of contraction with increase in muscle fiber length
Correct Answer: Strength of contraction without increase in muscle fiber length
Explanation:When the strength of contraction increases without an increase in fiber length, the EF increases.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
00
Correct
00
Incorrect
00
:
00
:
00
Session Time
00
:
00
Average Question Time (
Secs)