Test: Circulatory System - 2 - JAMB MCQ

Normal blood pressure is below 120/80 mm Hg. If you're an adult and your systolic pressure is 120 to 129, and your diastolic pressure is less than 80, you have elevated blood pressure. High blood pressure is a systolic pressure of 130 or higher,or a diastolic pressure of 80 or higher, that stays high over time.

• The ventricular pressure decreases during the ventricular diastole or when the ventricles relax.
• The tricuspid and bicuspid valves open to allow blood to flow from the atria to the ventricles.

Deoxygenated blood from the upper part of the body returns to the right atrium (RA) via the superior vena cava. On the other hand, deoxygenated blood from the lower portion of the body returns to the RA via the inferior vena cava.

When the RA is full, it contracts which builds up the pressure and opens the tricuspid valve. Blood transfers from the RA into the right ventricle (RV). When the RV is filled, the walls of the ventricle begin to contract and the pressure within the RV rises. The increased pressure closes the tricuspid valve and blood is pumped into the pulmonary artery through the pulmonic valve.

So, the correct answer is option C.

• We know that the heart beats 70-75 times per minute. It beats approximately 72 times per minute.
• Hence, 72 cardiac cycles take place in one minute.
• Therefore, the duration of one cardiac cycle is 0.8 seconds.

• 72 cardiac cycles take place in one minute.
• The duration of one cardiac cycle is 0.8 seconds.
• During each cardiac cycle, each of the two ventricles pump 70 ml of blood, which is known as the stroke volume.

• Cardiac output is the product of the stroke volume and the heart rate.
• It is the total amount of blood pumped by each ventricle per minute.
• The average cardiac output of a healthy adult is 5000ml.

The first heart sound (lub) is associated with the closure of the tricuspid and bicuspid valves in other words beginning of ventricular systole whereas the second heart sound (dub) is associated with the closure of the semilunar valves.

• The average cardiac output of a healthy adult is 5000ml or 5 liters.
• This means that if the heart rate is 72 beats per minute and the stroke volume is 70ml, then around 5000ml of blood is pumped by each ventricle in one minute.

The P-wave represents the electrical excitation of depolarisation of the atria which leads to the contraction of both the atria. The T-wave represents the repolarisation of the ventricles.

• The QRS complex represents the depolarisation of the ventricles, which initiate the ventricular contraction.
• The contraction starts shortly after Q and marks the beginning of the systole.

Phylum Arthropoda and Mollusca include open circulatory system . Fish is member of phylum Chordata which contain close circulatory system.
Cockroach and scorpion are members of class inscecta phylum Arthropoda.

• By counting the number of QRS complexes that occur in a given period, one can determine the heartbeat rate of an individual.
• Any deviation from the shapes of the curve indicates a possible abnormality or a disease.
• Hence, it is of great clinical significance.

CAD refers to coronary artery disease which is caused by atherosclerosis and arteriosclerosis. Atherosclerosis refers to the deposition of cholesterol, fat, calcium on the walls of coronary arteries while arteriosclerosis refers to the deposition of calcium which leads to the hardening of the arteries.