Test: Circulatory Pathway & Double (August 17) - NEET MCQ

The valve present between the left atrium and left ventricle is the Bicuspid valve (also known as Mitral valve). During ventricular contraction, the bicuspid valve prevents backward movement of the blood, i.e. from the left ventricle into the left atrium. 

SA node is located in right upper corner of right atrium.
Electrical activity spreads through walls of atria and cause them to contract. This forces blood into ventricles.

The duration of the cardiac cycle is reciprocal of heart rate. Assuming a heart rate of 75 beats per minute, each cycle takes 0.8sec.

An adult human has been estimated to have some 60,000 miles (96,560 km) of capillaries with a total surface area of some 8001000 m2. The total volume of this system is roughly 5 liters, the same as the total volume of blood.

Blood pressure is the measurement of the pressure of the blood in the artery. Blood pressure peaks when the heart muscle contracts and pumps blood, a cycle called systole. It falls when the heart relaxes and refills with blood, a cycle called diastole. Systole is the top number and diastole is the bottom number. An optimal blood pressure level is a reading under 120/80 mmHg. Readings over 120/80mmHg and up to 139/89mmHg are in the normal to high range.

The right atrioventricular valve is also known as the tricuspid valve, since it has three cusps, or flaps, that open and closes. When this valve is open, blood flows freely from the right atrium into the right ventricle. However, when the right ventricle begins to contract, the valve closes, so that blood cannot return to the right atrium; this ensures forward flow into the pulmonary artery.
So, the correct answer is option A.

The sino-atrial (SA) node is a specialised bundle of neurons located in the upper part of the right atrium of the heart. The cardiac impulse originating from the SA node triggers a sequence of electrical events in the heart, thereby controlling the sequence of muscle contraction that pumps blood out of the heart. Since the SA node initiates and maintains the rhythmicity of the heart, it is known as the natural pacemaker of the human body.

The deoxygenated blood moves from the right ventricle to the lungs through the pulmonary artery. The oxygenated blood from lungs flows back to the left auricle through pulmonary vein. Then, by auricular contraction, oxygenated blood reaches the left ventricle.

Hemocytometer is a device used to count red blood cells.
Haemoglobinometer is an apparatus for measuring the amount of hemoglobin.
Sphygmomanometer is used to measure blood pressure.
Electrocardiogram is the recording of the electrical activity of the heart.
Thus, the correct answer is option (B), 'Haemocytometer'.