Circulatory System MCQ Quiz - Objective Question with Answer for Circulatory System - Download Free PDF

The correct answer is A, B, and C only

Concept:

• The cardiac activities of the heart are tightly regulated by intrinsic and extrinsic mechanisms.
• The intrinsic mechanism includes the nodal tissue, which generates and propagates electrical impulses within the heart, while the extrinsic mechanism involves the nervous system and hormones that modulate the heart's activity.
  • Normal activities of the heart are regulated intrinsically, i.e., autoregulated by specialised muscles (nodal tissue), hence the heart is called myogenic.
  • A special neural centre in the medulla oblangata can moderate the cardiac function through autonomic nervous system (ANS).
  • Neural signals through the sympathetic nerves (part of ANS) can increase the rate of heart beat, the strength of ventricular contraction and thereby the cardiac output.
  • On the other hand, parasympathetic neural signals (another component of ANS) decrease the rate of heart beat, speed of conduction of action potential and thereby the cardiac output.
  • Adrenal medullary hormones can also increase the cardiac output.

Explanation:

• A. Nodal tissue: The heart has specialized nodal tissues, such as the sinoatrial (SA) node and atrioventricular (AV) node, which generate and conduct electrical impulses. The SA node is known as the natural pacemaker of the heart, initiating rhythmic contractions. This is a critical intrinsic mechanism for regulating heart activity.
• B. A special neural center in the medulla oblongata: The medulla oblongata in the brainstem contains the cardiovascular center that regulates heart rate and blood pressure. This center has two components: the cardiac accelerator center (sympathetic stimulation increases heart rate) and the cardiac inhibitory center (parasympathetic stimulation decreases heart rate). This represents the extrinsic neural regulation of the heart.
• C. Adrenal medullary hormones: Hormones such as adrenaline and noradrenaline secreted by the adrenal medulla play a vital role in increasing heart rate and the force of cardiac contractions during stress or emergencies, part of the "fight or flight" response.

Other options:

• D. Adrenal cortical hormones: These hormones, such as cortisol and aldosterone, are involved in long-term stress responses and electrolyte balance, but they do not play a direct role in the immediate regulation of cardiac activities. Therefore, this option is incorrect.

The correct answer is Neural signals through the parasympathetic nerves

Concept:

• The autonomic nervous system regulates involuntary physiological functions, including heart rate. It consists of two main branches: the sympathetic and parasympathetic nervous systems.
• The sympathetic nervous system prepares the body for stress-related activities ("fight or flight"), while the parasympathetic nervous system promotes relaxation and recovery ("rest and digest").

Explanation:

• Neural signals through the parasympathetic nerves: The parasympathetic nervous system decreases the rate of the heartbeat by releasing acetylcholine through the vagus nerve. Acetylcholine acts on the pacemaker cells in the heart to slow down the heart rate.
• Neural signals through the sympathetic nerves: These signals increase the heart rate by releasing norepinephrine, which stimulates the pacemaker cells in the heart, making them fire more rapidly.
• Hormone of adrenal medulla: The adrenal medulla releases adrenaline (epinephrine) and norepinephrine into the bloodstream, both of which increase the heart rate and prepare the body for a "fight or flight" response.

The correct answer is a - i, b - iii, c - iv, d - ii

Explanation:

• Basophils: Basophils secrete histamine, serotonin, heparin, etc., and are involved in inflammatory reactions.
• Neutrophils: Neutrophils and monocytes (6-8 per cent) are phagocytic cells which destroy foreign organisms entering the body.
• Plasma cells: These cells are derived from B-lymphocytes and are responsible for producing antibodies, which are crucial for the immune response.
• Eosinophils resist infections and are associated with allergic reactions.

The correct answer is 

Explanation:

• White Blood Cells (W.B.C.) are a crucial component of the immune system and help in defending the body against infectious diseases and foreign invaders.
• There are several types of W.B.C., each with a different function and percentage in the blood.
• The main types of W.B.C. include Basophils, Neutrophils, Eosinophils, Monocytes, and Lymphocytes.

The correct answer is A-ii, B-iii, C-i

Concept:

• The heart consists of four chambers: two atria (left and right auricles) and two ventricles (left and right ventricles).
• Valves in the heart ensure unidirectional blood flow and prevent backflow. The main valves are the tricuspid valve, bicuspid (mitral) valve, pulmonary valve, and aortic valve.
• The bicuspid valve, also known as the mitral valve, is specifically located between the left atrium (auricle) and the left ventricle. It allows blood to flow from the left atrium into the left ventricle and prevents backflow when the ventricle contracts.
• The tricuspid valve is to prevent the backflow of blood from the right ventricle into the right atrium during ventricular contraction (systole).
• Semilunar valves are located at the bases of the aorta and pulmonary artery.

Explanation:

• Bicuspid (Mitral) Valve: This valve is located between the left atrium and the left ventricle. It is called the bicuspid valve because it has two cusps or flaps. It prevents backflow of blood from the left ventricle to the left atrium. Therefore, the correct match is A-ii.
• Semilunar Valve: These valves are located at the base of the large arteries leaving the heart. The two semilunar valves are the aortic valve, located between the left ventricle and the aorta, and the pulmonary valve, located between the right ventricle and the pulmonary artery. The one mentioned in the question is the pulmonary semilunar valve, which is between the right ventricle and the pulmonary artery. Therefore, the correct match is B-iii.
• Tricuspid Valve: This valve is located between the right atrium and the right ventricle. It has three cusps or flaps, hence the name tricuspid. It prevents backflow of blood from the right ventricle to the right atrium. Therefore, the correct match is C-i.

The correct answer is O^-

Explanation:

• The O-ve negative is the universal donor blood group.
• It has a low risk of causing transfusion reactions.
• O-ve is given in the case of emergency if the blood group is not known.
• Red blood cells have antigens on the surface and antibodies in the plasma.
• It has four major types of antigens.
  • Type A: It has A antigens on the surface of the red blood cells and anti-B antibodies in the plasma.
  • Type B: It has B antigens on the surface of the red blood cells and anti-A antibodies in the plasma.
  • Type AB: It has both A and B antigens on the surface of the red blood cells and no antibodies in the plasma.
  • Type O: It has no antigens, but both anti-A and anti-B antibodies in the plasma.

Each group can be either RhD +ve or RhD -ve.

The correct answer is Arteries.Key Points

• Arteries are thick-walled blood vessels that carry oxygenated blood away from the heart to various organs of the body.
• They have a muscular wall that contracts and relaxes to regulate blood pressure and flow.
• Arteries also branch out into smaller vessels called arterioles, which further divide into capillaries where exchange of nutrients and waste products takes place.
• Veins, on the other hand, carry deoxygenated blood back to the heart from various organs of the body.
• Tracheas are part of the respiratory system and carry air to and from the lungs.

Additional Information

• Veins:
  • These are thin-walled blood vessels that have valves to prevent backflow of blood.
  • They are located closer to the surface of the skin and are often visible as blue or greenish lines.
• Plasma:
  • This is the liquid component of blood that carries nutrients, hormones, and waste products.
  • It also helps in maintaining the pH balance and temperature of the body.
  • Plasma is not a vessel but a component of blood.

The correct answer is Iron.Key Points

• If iron levels are low haemoglobin is not synthesized in sufficient amounts and the oxygen-carrying capacity of red blood cells is reduced, resulting in anaemia.
• Iron is a trace mineral that we need in small quantities every day. 
• It is slightly water soluble and is a cation that exists in two states, +2 (ferrous) or +3 (ferric).
• The great majority of iron used in the body is recycled from the continuous breakdown of red blood cells.

Additional Information 

• Chromium: Chromium is a chemical element with the symbol Cr and atomic number 24. It is the first element in group 6.
• Iodine: Iodine is a chemical element with the symbol I and atomic number 53.
• Magnesium: Magnesium is a chemical element with the symbol Mg and atomic number 12. 

The correct answer is O.

Key Points 

• O blood groups are known as universal donors.
  • People with type O- blood are called universal donors because their donated red blood cells have no A, B, or Rh antigens and can therefore be safely given to people of any blood group.
  • A universal donor is a person who can donate blood to any recipient of any blood group. 

Additional Information 

• AB-positive blood type is known as the “universal recipient” because AB-positive patients can receive red blood cells from all blood types.
• B positive is an important blood type for treating people with sickle cell disease and thalassemia who need regular transfusions.
  • These conditions affect South Asian and Black communities where B-positive blood is more common.
  • There is currently a very high demand for B positive donations with the subtype Ro.
• Landsteiner discovered the ABO blood group system by mixing the red cells and serum of each of his staff.

Key Points

• Enzymes are biocatalysts and are almost made up of proteins.
• Enzymes accelerate biochemical reactions of respiration, digestion, excretion, etc.
• These lower the activation energy of the reactions.
• Each enzyme is specific for a specific reaction and highly active under optimum temperatures.
• Enzymes are divided into 6 classes and named accordingly by a four-digit number.
• These are- Oxidoreductases/ dehydrogenases, Transferases, Hydrolases, Lyases, Isomerases, and Ligases.

Explanation:

• Some enzymes are commercially used in a variety of industries such as pharmaceuticals, chemical production, biofuels, food & beverage, and consumer products.
• In food and beverage industries, fermentation of sugar by the enzyme action in yeast leads to the formation of carbon dioxide gas.
• This process gives texture to bread, pastries, and alcoholic beverages.
• Enzyme action can be inhibited or promoted by the use of drugs that tend to work around the active sites of enzymes.
• Tissue plasminogen enzyme is made by the cells lining blood vessels and has also been produced synthetically in the pharmaceutical industries.
• The primary function of tissue plasminogen is to dissolve the blood clots in heart attack patients.
• The tissue plasminogen activator catalyzes the conversion of plasminogen to plasmin.
• Plasmin is an enzyme involved in dissolving blood clots.

Hence, the correct answer is option (2).

Concept:

A narrowing of the coronary arteries that prevents adequate blood supply to the heart muscle is called Coronary Artery Disease (CAD). It is also known as ;Coronary Arteriosclerosis.
CAD is usually caused by atherosclerosis which is the abnormal accumulation of lipid in the lumen of the coronary artery.

Key Points
Risk Factor:

Modifiable: 

• High blood cholesterol level i.e. normal should be
• Total cholesterol < 200mg/dl
• HDL > 60mg/dl
• LDL < 100mg/dl
• Triglycerides < 150mg/dl
• Cigarette smoking, tobacco use (Hence option 4 is correct)
• Hypertension
• Diabetes mellitus
• Limited physical activity
• Obesity
• Non-modifiable factors

Family history of coronary artery disease

• Increasing age
• Gender (most common in males)
• Race- non-white populations

 Additional Information

• Symptoms of CAD- include chest pain angina pectoris myocardial infarction diaphoresis dysrhythmias dyspnea and fatigue.
• Diagnosis-  history collection, physical examination, ECG, cardiac enzymes, and stress test.
• Management beta-blockers, calcium channel blockers, ACE inhibitors, nitrates.

The correct answer is veins.

Key Points

• Veins carry carbon dioxide-rich or deoxygenated blood from all parts of the body back to the heart.
• Your body has veins, which are blood vessels that gather blood with low oxygen content and return it to your heart.
  • Pulmonary veins are an exception to this rule. These four veins, located between your heart and lungs, carry oxygen-rich blood from your lungs back to your heart.
• A component of your circulatory system are veins. To keep your blood flowing, they cooperate with your heart and other blood veins.
• The majority of your blood is stored in your veins. Your veins actually contain around 75% of your blood.
• Common problems with veins include chronic venous insufficiency, deep vein thrombosis and varicose veins.

Additional Information

• Your body uses arteries, which are a component of the circulatory or cardiovascular system, to transport oxygen-rich blood from your heart to every cell in your body.
  • They are essential for the proper distribution of hormones, nutrients, and oxygen throughout your body.
  • Because they carry nutrients to your body's cells and tissues, arteries help your body stay alive and healthy.

  • There are two varieties of arteries:

    • Elastic: Found near your heart, they have more elastic tissue than muscular arteries. Aorta and pulmonary artery are two examples.

    • Smooth (muscular) muscle is more prevalent than elastic arteries in the muscle. Brachial, radial, and femoral arteries are a few examples.

• Capillaries are delicate blood vessels that exist throughout your body.
  • They transport blood, nutrients and oxygen to cells in your organs and body systems.
  • They are the smallest blood vessels in your vascular system. 
  • They ​complete the circulatory system by connecting arteries to veins.
• The basic building blocks of the brain and nervous system are neurons, also known as neurones or nerve cells.
  • Neurons are the cells that receive sensory information from the outside world, give motor commands to our muscles, and convert and relay electrical signals at each stage along the way.
  • Their encounters, more than anything else, shape who we are as individuals.
  • Nevertheless, there is interaction between our about 100 billion neurons and other cell types that are often referred to as glia (these may actually exceed neurons, but it's not truly known).

The correct answer is Four.

Key Points

• Each unit of blood donated is separated into four major components, platelets, plasma, red blood cells, and white blood cells, which can be used to save at least three lives. 
  • So to save the lives of 12 people one needs to donate blood at least 4 times a year.
  • Against the requirement of about 10-11 million units of blood each year, the annual collection in India is 8.5-9 million units.
  • Voluntary donations account for around 80% of blood donations in India.
  • The WHO estimates that between 1% and 3% of a country’s population need blood in a year.
  •  About 65% of India’s population are young adults and even if half of them donate blood a couple of times a year, shortages will not happen.

Additional Information Who can donate blood

• Any healthy person between the ages of 18 and 65.
• Must be free of all major illnesses.
• Must not have a seasonal infection.
• Should not be on antibiotics, blood thinners or antidepressant medicines.
• Must not be pregnant or lactating.
• Should not be anaemic: haemoglobine lower than 12.5gm/dl.
• Should not have donated within the last three months.

Concept:

Human circulatory system:

• The organ system of human beings or other organisms which is responsible for the transport of materials inside the body is called the circulatory system.
• Our circulatory system consists of a muscular pumping organ called the heart, arteries, veins, capillaries, and blood.
• The heart has two atria and two ventricles.
• The heart acts as a pump to push out blood. 
• The arteries, veins, and capillaries act as tubes or pipes through which blood flows. These tubes which carry blood are called blood vessels.
• Arteries carry oxygenated blood away from the heart except the pulmonary artery carries deoxygenated blood.
• Veins carry deoxygenated blood away from the heart except the pulmonary veins carry oxygenated blood.

Explanation:

• For double circulation, there are 2 circulatory pathways: 
  • Systematic circulation
  • Pulmonary circulation
• Systematic circulation 
  • It carries oxygenated blood from the heart to all parts of the body through a complex system of arteries and capillaries.
  • It also carries deoxygenated blood from these organs back to the heart through veins.
• Pulmonary circulation 
  • After the heart receives the deoxygenated blood from different parts of the body, it pumps blood to the lungs for expelling the CO₂ and collecting oxygen.
  • After that, the oxygenated blood is sent back to the heart for systematic circulation.
• Thus, the systematic circulation carries blood from the heart to all the other parts of the body and back again. Hence, statement 1 is incorrect.
• And, the pulmonary circulation is a short loop from the heart to the lungs and back again. Hence, statement 2 is incorrect.

Therefore, the correct answer is Statements 1 and 2 are wrong.

Additional Information

• Open circulatory system: Examples- insects. and prawns etc.
• Closed circulatory system: Examples- mollusks, echinoderms, and all vertebrates.

The correct answer is Aorta

Key Points

• Aorta  is the largest artery of the human body.
• The aorta is a tube about a foot long and just over an inch in diameter.
• The aorta begins at the top of the left ventricle, the heart's muscular pumping chamber.
• The heart pumps blood from the left ventricle into the aorta through the aortic valve.

Additional Information