Test: Body Fluids and Circulation - NEET 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.

• In the given diagram of the cross section of the heart, the indicated valve is the bicuspid valve.
• It is also known as the mitral valve.
• The bicuspid valve is the opening between the left auricle and left ventricle.

• In the given diagram of the cross-section of the heart, the indicated structure is the superior vena cava.
• The superior vena cava delivers deoxygenated blood from the upper parts of the body to the heart.

• In the joint diastole state, all four chambers of the heart are relaxed.
• The tricuspid and bicuspid valves are open while the semilunar valves are closed.
• Blood from pulmonary vein flows into the left ventricle.

The heart sound ‘’DUP’’ is produced when a semilunar valve at the base of aorta classes.
Two distinct sounds can be heard during a heart beat with the help of a stethoscope. These are 'lubb' and 'dup'.Lubb is the first sound which has a low pitch and produced by the closure of tricuspid and bicuspid valves (collectively called atrioventricular valves) at the beginning of ventricular systole.
Dup is the second sound which is sharp and has a high pitch. It is produced by closure of semilunar valves by the end of ventricular systole.

• During the atrial systole, both the atria contract simultaneously while the ventricles remain relaxed.
• It occurs due to the action potential generated by the SAN.
• The tricuspid and bicuspid valves open.

• SAN or the sinoatrial node is auto excitable and is responsible for generating the action potential.
• This action potential is transmitted to the ventricles via the AVN, the AV bundle and the Bundle of His.

• The relaxation of the atria or the atrial diastole coincides with the contraction of the ventricles or the ventricular systole.
• The right and left semilunar valves open up due to the increase in pressure in the ventricles.

The blood pumped by the right ventricle enters the pulmonary artery, whereas the left ventricle pumps blood into the aorta. The deoxygenated blood pumped into the pulmonary artery is passed onto the lungs from where the oxygenated blood is carried by the pulmonary veins into the left atrium. This pathway constitutes the pulmonary circulation. The oxygenated blood entering the aorta is carried by a network of arteries, arterioles, and capillaries to the tissues from where the deoxygenated blood is collected by a system of venules, veins and vena cava and emptied into the right atrium. This is the systemic circulation. The systemic circulation provides nutrients, O2 and other essential substances to the tissues and takes CO2 and other harmful substances away for elimination.
So, the correct answer is option A.

Veins carry the deoxygenated blood from the body to the heart.
Any arteries or veins that originate from the heart are known as pulmonary veins and arteries.
Pulmonary veins are the only veins in the entire body that carries the pure blood from the lungs through the heart after the purification.
The oxygenation of the blood takes place in the lungs and this oxygenated blood is done carried by the pulmonary veins.

A node is a specialized type of tissue that behaves as both muscle and nervous tissue. There are 2 nodes present in the human heart. SA node and AV node. 
The sinoatrial node, also referred to as the pacemaker of the heart, coordinates heart contractions. Located in the upper wall of the right atrium, it generates nerve impulses that travel throughout the heart wall causing both atria to contract.
The atrioventricular node lies on the right side of the partition that divides the atria, near the bottom of the right atrium. When the impulses generated by the SA node reach the AV node, they are delayed for about a tenth of a second. This delay allows the atria to contract, thereby emptying blood into the ventricles. The AV node then sends the impulses down the atrioventricular bundle. This bundle of fibers branches off into two bundles and the impulses are carried down the center of the heart to the left and right ventricles. 
Hence, the correct answer is option B.

During cardiac cycle in humans, the blood pumped by the right ventricle enters the pulmonary artery, whereas the left ventricle pumps blood into the aorta. The deoxygenated blood pumped into the pulmonary artery is passed onto the lungs from where the oxygenated blood is carried by the pulmonary veins into the left atrium. This pathway constitutes the pulmonary circulation.

Diastole This should really be called “ventricular diastole”, but don't worry about this for GCSE. During diastole the thick muscular walls of the ventricles relax. Again, this happens to both sides of the heart. The pressure of the blood in the ventricles falls low enough for the bicuspid valve to open.

The human heart is an example of myogenic heart, it possesses cardiac muscle helping the heart to automatically contract spontaneously; which do not need any stimuli as in neurogenic heart. A myogenic heart is capable of generating a cardiac contraction independent of nervous input. In a myogenic heart, contraction is initiated by the cells called myocyte  (Pacemakers)itself instead of an outside occurrence or stimulus such as nerve innervation.

In the human heart, the opening between the right atrium and the right ventricle is guarded by a valve formed of three muscular flaps or cusps, the tricuspid valve, whereas a bicuspid or mitral valve guards the opening between the left atrium and the left ventricle.
So, the correct answer is option C.