31 Years NEET Previous Year Questions: Body Fluids & Circulation - 1 - NEET MCQ

Fibrins are formed by the conversion of inactive fibrinogens in the plasma by the enzyme thrombin.

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

Stroke volume = End diastolic volume - End systolic volume
= 100 - 50 = 50 mL
Cardiac output = Heart beat x stroke volume
∴ Heart beat = Cardiac output/Stroke volume = 5000 / 50 = 100 beats per minute

Arter y is blood vessel which receives blood from heart, has elastic thick wall shows jerky movements due to pumping activity of heart. Vein is a blood vessel which carries blood towards the heart, has wider lumen with internal valves where blood flows smoothly and slowly. Blood capillary is a very fine blood vessel which has a single layered wall. Pulmonary veins are the only veins which carry oxygenated blood. (_PO₂ = 95 mmHg, _PCO₂ = 40 mmHg)

B-lymphocytes cells are involved in antibody production.

The P-wave represents the electrical excitation (or depolarisation) of the atria, which leads to the contraction of both the atria. The  QRS complex represents the depolarisation of the ventricles, which initiates the ventricular contraction. The contraction starts shortly after Q and marks the beginning of the systole.

Spleen is an organ of the lymphatic system located in the left side of the abdominal cavity under the diaphragm, the muscular partition between the abdomen and the chest. It is called graveyard of RBC because fragment of red blood cells, old and dead cells are constantly being removed from the blood streams by it.

70% to 75% CO₂ is transported as primary buffer of the blood. Bicarbonate ion (HCO₃) in blood plasma. When CO₂ diffuses from tissues into blood then it is acted upon by the enzyme carbonic anhydrase.

P wave is formed when the atria (the two upper chambers of the heart) contract to pump blood into the ventricles. 

QRS Complex is formed when the ventricles (the two lower chambers of the heart) are contracting to pump out blood. It is one complete pulse.

ST segment measures the end of the contraction of the ventricles to the beginning of the rest period before the ventricles begin to contract for the next beat.

T wave measures the resting period of the ventricles.

So, the correct answer is option C.

Hypertension is the term for blood pressure that is higher than normal (120/80). In this measurement, 120 mm Hg (millimeter of mercury pressure) is the systolic, or pumping, pressure and 80 mm Hg is the diastolic, or resting pressure. If repeated checks of blood pressure 190/100 mm Hg) of an individual is 140/90 (140 over 90) or higher, it shows hypertension. High blood pressure (190/100 mm Hg) leads to heart diseases and also affects vital organs like brain and kidney. 

Arteries are best defined as the vessels which break up into capillaries which reunite to form a vein.
Arteries are the blood vessels which carry oxygenated blood from the heart to the organs. It breaks up into several branches of capillaries before entering the organs. These capillaries again reunite to form venules and ultimately veins which carry the deoxygenated blood towards the heart. 

Fibrinogen, the protein of blood plasma is converted to insoluble protein fibrin during the clotting process. The fibrinogen free fluid obtained after removal of the clot, called blood serum is plasma minus fibrinogen.

‘Bundle of His’ are a typical cardiac muscle fibres, connecting the atria with ventricle.

In the given figure the exchange of respiratory gases occurs in alveolar cavity.

The pulmonary alveoli are the terminal ends of the respiratory tree, which are the gas exchange sites. The alveolar membrane is the gas exchange surface. Carbon dioxide rich blood is pumped from the rest of the body into the alveolar blood vessels where, through diffusion, it releases its carbon dioxide and absorbs oxygen.

Blood transports oxygen from respiratory organs to the tissue cells and also transports carbon dioxide from the tissue cells to the respiratory membrane. About 97% of oxygen is transported by RBCs in the blood while the remaining three percent of oxygen is carried in a dissolved state through plasma. Nearly 20-25% of carbon dioxide is transported by RBCs whereas 70% is carried as bicarbonate. About 7% of CO₂ is carried in dissolved state through plasma.

Tricuspid valve is the valve in the heart between the right atrium and right ventricle. The valve opens to allow blood to flow from atrium into the ventricle. Thus if tricuspid valve is partially nonfunctional, then the flow of blood into the pulmonary artery will be reduced

The three calle/es in ABO blood groups in humans can produce six different genotypes and four different phenotypes

Globulins contained in human blood plasma are primarily involved, in defence mechanism of body. Globulin is one of the two types of serum proteins, the other being albumin. Globulins can be divided into three fractions based on their electrophoretic mobility. Most of the alpha and beta globulins are synthesized by the liver, whereas gamma globulins are produced by lymphocytes and plasma cells in lymphoid tissue.

In a standard ECG, the P-wave is a small upward wave that indicates the depolarisation of the atria. This is caused by the activation of SA node.

Red blood cells are the most common type of blood cell and delivering oxygen to the body tissues via the blood. There is no DNA in mature RBC. The reticulocyte is the immediate precursor of the mature RBC and, within 24 hours of release into the peripheral circulation, evolves into the mature RBC.

Lymph is a mobile connective tissue comprising lymph plasma and lymph corpuscles. Its composition is just like blood plasma except that it lacks RBCs and large plasma proteins.

The ABO blood group system is the most important blood type system (or blood group system) in human blood transfusion. It is named ABO and not ABC, because blood group O (or blood group zero in some countries) individuals do not have either A or B antigens on the surface of their RBCs, but their blood serum contains IgM anti-A antibodies and anti-B antibodies against the A and B blood group antigens. Therefore, a group O  individual can receive blood only from a group O individual, but can donate blood to individuals of any ABO blood group (ie A, B, O or AB).

The action of heart includes contractions and relaxations of the atria and ventricles. Contraction of the heart is called systole and relaxation is called diastole. The dynamics of blood flow in blood vessels is no exception and blood flows through the blood vessels along a pressure gradient, always moving from higher to lower pressure areas. Fundamentaly, the pumping action of heart generates blood flow. The 'contraction of atria is initiated and activated   by   sinoatrial   node, which spreads waves of contraction across the wall of atria via muscle fibres at regular intervals.

The most active phagocytic white blood cells are neutrophils and monocytes. Neutrophil is a type of WBC (leucocyte) that has a lobed nucleus and granular cytoplasm. Neutrophils engulf bacteria and release various substance such as lysozyme and oxidizing agents. Monocyte is the largest form of WBC in vertebrates. It has a kidney shaped nucleus and is actively phagocytic, ingesting bacteria and cells debris.

Basophil is a type of white blood cell (leucocyte) that has a lobed nucleus surrounded by granular cytoplasm. Basophils are produced continually by stem cells in the red bone marrow & move about in an amoeboid fashion. Like, mast cells, they produce histamine and heparin as part of the body’s defences at the site of an infection or injury.

 Neries (belonging to class polychaeta of phylum Annelida), scorpion and cockroach (belonging to phylum arthropoda) and silver fish all have dorsal heart.

Blood serum is liquid minus clotting elements of pale yellow colour. It does not have fibrinogen and other clotting  materials. It does not take part in blood clotting. 

Periplaneta (P. americana, the Indian Cockroach) is an insect & insects do not have closed blood circulation. Their blood (called haemolymph) even does not serve for respiration. They do not possess blood vessels in this circulatory system and hence it is an open system. Hirudinaria is a pure exception for having a closed circulatory system, even though it belongs to the phylum Annelida, which generally has an open circulatory system. 

Transport of CO₂ is much easier than O₂ because of the higher solubility of CO₂ than O₂. Almost 7% of CO₂ is transported in dissolved state in plasma. About 23% of the CO₂ is transported in the form of Carbamino Compound called carbamino haemoglobin. 70% of CO₂ is transported in the form of bicarbonate ions. CO₂ reacts with water present in plasma.
Carbonic acid is unstable & gives H⁺ and HCO₃^–. H⁺ bind with haemoglobin to maintain the pH of blood while HCO₃^– remain in the blood and carries the CO₂ to lungs.

Folic Acid (Cyanocobalamine vit. B₁₂) works in the formation and maturation of RBCs. In the deficiency of this RBCs formation decreases and the formed RBCs will not mature i.e. they will not loose the nucleus and hence remain nucleated and lack haemoglobin. Such RBCs cannot carry oxygen & person suffers from anaemia. Supplementing his diet with folic acid and cobalamine will lead to the increased formation and proper maturation of enucleated RBCs with haemoglobin and eliminate anaemia.