Cardiovascular system

Hematology is the branch of science that deals with the study of blood, blood-forming tissues, and disorders related to them. It includes the study of blood cells, their formation, function, and interaction with other components of the circulatory system. Hematology is an important field of medicine as it helps in diagnosing and treating various blood-related disorders such as anemia, leukemia, and hemophilia.

The volume of blood in an average-sized adult male is not 15-16 liters. In fact, the total volume of blood in an adult male is around 5-6 liters, while in an adult female, it is around 4-5 liters. The pH of blood is slightly alkaline, with a range of 7.35-7.45. Blood constitutes around 20% of the extracellular fluid in the body and provides around 8% of the total body mass. These physical characteristics of blood are important to maintain the proper functioning of the body and to diagnose various disorders related to blood.

Blood transports various components throughout the body, including hormones, oxygen, carbon dioxide, nutrients, and waste products. However, heat is not transported by blood. Heat is mainly transferred through conduction, convection, and radiation. Blood plays a crucial role in maintaining the body's homeostasis and provides the necessary nutrients and oxygen to various organs and tissues. Lymph, on the other hand, is not transported by blood. It has its own set of vessels, and it helps in removing excess fluid and waste products from the tissues.

Fibronectin is not a plasma protein, but rather an extracellular matrix protein that helps in the binding of collagen and fibrin. On the other hand, albumin, globulin, and fibrinogen are all proteins found in plasma. Albumin is the most abundant plasma protein and is responsible for maintaining the oncotic pressure of the blood, while globulin plays a crucial role in the immune system. Fibrinogen is involved in the blood clotting process and is converted to fibrin during clot formation. Understanding the different plasma proteins and their functions is important in diagnosing and treating various diseases related to the blood.

Serum is the liquid portion of the blood that remains after the blood has clotted and the clot has been removed. It is similar to plasma but without the clotting factors such as fibrinogen. This makes serum useful in many laboratory tests, as it provides a clear sample for analysis. On the other hand, plasma is the liquid part of blood that contains all the blood components, including red blood cells, white blood cells, platelets, and proteins such as albumin, globulin, and fibrinogen. Understanding the differences between serum and plasma is important in the diagnosis and treatment of various diseases and conditions.

Hematocrit is the term used to define the amount or percentage of red blood cells (RBCs) present in the blood. It is typically expressed as a percentage, such as 40%, which means that 40% of the volume of blood is occupied by RBCs. Hemoglobin is a protein found in RBCs that carries oxygen, while hemopoiesis is the process of blood cell formation. Myoglobin is a protein found in muscle tissue that helps store and transport oxygen within muscle cells.

Hemopoiesis is the process of forming blood cells and begins in the yolk sac during embryonic development. As the fetus develops, the process also occurs in other organs such as the liver, spleen, thymus, and lymph nodes. However, the yolk sac is the primary site of hemopoiesis in the early stages of embryonic development.

Leucopenia is a condition where there is a decrease in the number of white blood cells, which are an essential component of the immune system. When the white blood cell count falls below 5000/microliter, it is considered to be abnormally low. This can be caused by a variety of factors, including viral or bacterial infections, bone marrow disorders, certain medications, or autoimmune diseases. It can lead to an increased risk of infection and other health problems.

Aplastic anemia is a rare condition in which the bone marrow fails to produce enough red blood cells, white blood cells, and platelets. This can occur due to toxic chemicals, radiation, certain medications, or viral infections. Without enough red blood cells, the body cannot get enough oxygen, leading to fatigue, weakness, and shortness of breath. Treatment options may include blood transfusions, medications to stimulate blood cell production, or a bone marrow transplant.

Thalassemia is a type of hemolytic anemia that results from a genetic defect that leads to the destruction of a large number of red blood cells. In thalassemia, the body is unable to produce enough hemoglobin, a protein that carries oxygen in the blood. As a result, the red blood cells become fragile and easily destroyed, leading to anemia. There are two main types of thalassemia, alpha and beta thalassemia, depending on which part of the hemoglobin molecule is affected. The severity of thalassemia can vary, from mild to life-threatening, depending on the number of defective genes inherited. Treatment may include blood transfusions, bone marrow transplants, or medications to remove excess iron from the body.

The pericardium is the protective membrane that surrounds the heart. It is made up of tough, dense, inelastic, and irregular connective tissues that help to prevent damage to the heart from external forces. The pericardium also contains a small amount of fluid that acts as a lubricant, reducing friction between the heart and surrounding tissues.

An ECG, or electrocardiogram, records the electrical changes in the myocardium layer of the heart. The body fluid contains ions that produce an electric current and cause changes in the myocardium. The other layers of the heart, including the epicardium, pericardium, and endocardium, do not play a role in the electrical activity of the heart that is recorded on an ECG.

The right ventricle of the heart contracts and pumps the blood out through the pulmonary artery. As the right ventricle fills up with blood from the right atrium, its pressure increases, and the walls of the ventricle start to contract. The tricuspid valve closes due to the increased pressure, and the pulmonic valve opens, allowing blood to flow into the pulmonary artery. The pulmonary artery has two sections, and the first section carries blood to the right lung while the other carries blood to the left lung. It is the only artery that carries deoxygenated blood from the heart to the lungs for oxygenation.

Christian Barnard, a South African cardiac surgeon, performed the world's first successful human-to-human heart transplant on December 3, 1967. Although the patient, Mr. Louis Washansky, died after 18 days, Barnard performed a second transplant, and the patient went on to live for almost 19 months. This groundbreaking surgery was a significant milestone in medical history and paved the way for further advancements in heart transplantation. Barnard is widely regarded as the founder of heart transplantation, and his contributions to medical science continue to inspire future generations of medical professionals.

The spleen can be called a "blood bank" because it filters and stores blood cells for emergency situations such as hemorrhagic shock. It is often referred to as the "graveyard of blood" as it purifies the blood by removing microbes and worn-out red blood cells. The spleen is located in the upper left abdomen, beneath the ribcage and above the stomach, just below the diaphragm.

The pulmonary artery is responsible for carrying deoxygenated blood from the heart to the lungs for oxygenation. It is the only artery in the human body that does not transport oxygenated blood. After the blood is oxygenated in the lungs, it returns to the heart through the pulmonary veins. The systemic artery carries oxygenated blood to the body from the left ventricle of the heart. The hepatic artery carries oxygenated blood to the liver, while the cardiac artery supplies blood to the heart muscle itself.

A closed-type circulatory system is a system in which blood is pumped through a continuous network of vessels. Among the given options, only fish belong to the phylum Chordata which has a closed circulatory system. In contrast, phylum Arthropoda and Mollusca have an open circulatory system. Cockroaches and scorpions belong to the class Insecta phylum Arthropoda, which means they have an open circulatory system. Fishes have a two-chambered heart and a closed circulatory system that pumps blood through the gills to oxygenate it before circulating it through the rest of the body. The closed circulatory system enables fish to have a more efficient and higher-pressure circulatory system than animals with an open circulatory system.

Angiology is the branch of medicine that deals with the study of the lymphatic and circulatory systems, including the arteries, veins, and lymphatic vessels. It involves the diagnosis and treatment of various illnesses related to these systems, including conditions like varicose veins, blood clots, and lymphedema. Angiologists are medical specialists who specialize in this field and use a variety of diagnostic tools to evaluate and treat patients with circulatory system disorders. Other related fields include cardiology, which focuses on the heart, and hematology, which focuses on blood disorders. Osteology, on the other hand, is the study of bones and skeletal tissues, and is not directly related to the circulatory system.

The atrioventricular septum separates the atria and ventricles of the human heart and is composed of fibrous and adipose tissues. It is formed by an extension or crest of the interventricular septum on the left and anterior membranous and inferior muscular parts that emerge from the right atrial septal wall. While cartilage and mucous membrane are found in other parts of the body, osteocytes are cells found in bone tissue and are not present in the atrioventricular septum.

The atrioventricular (AV) node is a small component of the heart located in the lower-left corner of the right atrium. It is responsible for transmitting electrical signals to the ventricles, causing them to contract and pump blood out of the heart. The atrioventricular septum is a wall of tissue that separates the atria and ventricles of the heart, and is located near the AV node. Therefore, the correct answer is option C. The sinoatrial node (SAN) is located in the upper-right corner of the right atrium and is responsible for generating the electrical impulses that regulate the heart's rhythm. The left ventricle is one of the four chambers of the heart and is responsible for pumping oxygenated blood to the body. The aorta is the largest artery in the body and is responsible for carrying oxygenated blood away from the heart to the rest of the body.

The correct answer is option C, the Sinus Node, which is also known as the natural pacemaker of the heart. The sinus node is a cluster of myocytes that act as pacemakers, initiating the heart's contractions. The sinus node can generate approximately 70 to 75 action potentials each minute, which trigger the heart muscles to contract.
The Purkinje fibers, option A, are a network of specialized cardiac muscle fibers that relay electrical impulses from the AV node to the ventricles. The AV node, option B, is a region of the heart that slows down the electrical signal coming from the atria before passing it on to the ventricles. The Bundle of His, option D, is a collection of fibers that transmits the electrical impulses from the AV node to the ventricles.

The correct answer is option A, 250- 300 gm. The size of the human heart is roughly the same as a clenched fist. An adult human heart usually weighs between 250 to 350 gm, making up approximately 0.45% of the total weight of the body. However, the weight of the heart can vary slightly based on an individual's physical size and sex.
Option B, 250- 350 gm, is close to the actual weight of the human heart, but the range is slightly larger than the typical weight range. Option C, 350- 450 gm, and option D, 300- 400 gm, are outside the typical weight range of the human heart.

The correct answer is option B, Villi. Villi are tiny, finger-like projections found in the small intestine that play a role in absorbing nutrients from food. They are not a component of the circulatory system.
Option A, Capillaries, are the smallest blood vessels in the body that spread out like a mesh to carry blood to every area of the body. Option C, Veins, are tubes that carry blood from the body to the heart and back again. And option D, Arteries, are blood vessels that carry oxygenated blood away from the heart to the rest of the body, with the exception of the pulmonary and avascular arteries.

The correct answer is option D, Bone Marrow. Bone Marrow is a soft tissue found inside the medullary cavities of bones, primarily in the hip and thigh bones. It generates immature cells called stem cells that can develop into various types of cells later on. There are two types of stem cells: mesenchymal and hematopoietic. While mesenchymal cells develop into fat, cartilage, and bones, hematopoietic cells develop and turn into blood cells, including red blood cells (RBCs), white blood cells (WBCs), and platelets.
Options A, Heart, B, Lymph Nodes, and C, Liver, are not involved in the production of red blood cells. The heart is a muscular organ that pumps blood throughout the body, lymph nodes are small bean-shaped structures that help filter lymph fluid and fight infections, and the liver is a large organ that produces bile and plays a role in detoxification and metabolism.

The heart is surrounded by a double membrane sac known as the pericardium, which is the outermost protective layer of the heart. The pericardium consists of an inner double layer of serous membrane and an outer fibrous layer. The pericardium helps to protect the heart and prevent it from overexpansion. The other options listed in the question are not related to the protective layer of the heart. The plura refers to the double-layered membrane that surrounds the lungs and lines the chest cavity. The kura is not a medical term. The epicardium refers to the outermost layer of the heart wall, which is part of the heart itself and not a protective layer. Therefore, the correct answer is option D, Pericardium.

The aorta is the largest artery in the human body and originates from the left ventricle of the heart. It carries oxygenated blood from the heart to the rest of the body. The coronary arteries supply oxygenated blood to the heart muscles, while the pulmonary artery carries deoxygenated blood from the right ventricle of the heart to the lungs for oxygenation. The blood in the pulmonary artery is low in oxygen and high in carbon dioxide. The pulmonary veins return oxygenated blood from the lungs to the left atrium of the heart. Any obstruction in the coronary arteries can cause a heart attack.

The heart contains four valves that work as doors to regulate the blood flow between the chambers of the heart. These valves open and close in sync with the heartbeat to ensure the proper direction of blood flow. The two atrioventricular (AV) valves located between the upper and lower heart chambers prevent the backflow of blood from the ventricles to the atria during contractions. The two semilunar valves located between the ventricles and arteries prevent the backflow of blood from the arteries to the ventricles during relaxation. These valves are crucial for the proper functioning of the heart and to maintain healthy circulation throughout the body.

The spleen plays several important roles in the body. It functions as a filter for blood, and as a component of the immune system, it helps to fight off certain types of germs. Additionally, the spleen stores platelets and white blood cells, and recycles old red blood cells. It can also store up to a cup of reserve blood that can be released into the body when there is a deficiency. This function can help to maintain a healthy balance of fluids and prevent issues like anemia.

Ischemia refers to the inadequate blood supply to a particular bodily region, leading to a reduction in the blood flow and oxygenation to that region. It can be caused by various factors such as partial or complete blockage of arteries, blood clots, or constriction of blood vessels. Inadequate blood supply to the heart muscle is known as cardiac ischemia, which can lead to a heart attack. Ischemia can also occur in other organs such as the brain, kidneys, and limbs, leading to serious health issues if left untreated. Therefore, prompt medical attention is necessary to prevent complications and improve outcomes.

The normal pH level of human blood is 7.4, which is mildly basic. The pH scale is used to determine whether a substance is acidic or basic. The pH scale ranges from 0 to 14, with 7 considered neutral. The letter "pH" stands for "power of hydrogen" and it measures the concentration of hydrogen ions in a solution. A pH of less than 7 is considered acidic, while a pH greater than 7 is basic or alkaline. A balanced pH is necessary for the proper functioning of the body's metabolic processes. Any changes in pH levels can lead to health problems. In the case of blood, an imbalance in pH can lead to acidosis or alkalosis, which can have serious consequences for the body.

Heparin is a natural anticoagulant present in the blood that is produced by basophils and mast cells. It works by binding to the enzyme inhibitor antithrombin III (AT), which in turn inactivates thrombin, factor Xa, and factor IIa. These factors are involved in the coagulation cascade of blood, which can lead to the formation of blood clots. By blocking these factors, heparin prevents blood clots from forming and is used as a medication to prevent and treat blood clots in medical conditions such as deep vein thrombosis, pulmonary embolism, and heart attacks.

Blood clotting is initiated by the activation of several clotting factors, which are in turn activated by calcium. Thus, calcium is the mineral ion that plays the main role in blood clotting. In the absence of sufficient calcium, the clotting process may be impaired, leading to excessive bleeding. It is important to note that excessive calcium can also lead to abnormal clotting, so maintaining a proper balance of calcium in the blood is crucial for proper clotting function.

The absolute period refers to the period when the entire heart is in diastole, i.e., the relaxation phase, and there is no contraction. During this phase, the heart is filling up with blood from the atria, and there is no ejection of blood into the ventricles. The duration of this period is around 0.2 seconds. After this, the atria contract, and the ventricles start to fill, leading to the ventricular systole or the contraction phase. Thus, option A is the correct answer.

Adrenaline or epinephrine is a hormone produced by the adrenal glands that acts on the sympathetic nervous system to increase heart rate, contractility, and oxygen consumption of the heart. Adrenaline has a positive inotropic effect, which means it increases the force of contraction of the heart. Adrenaline also increases the heart rate, or the number of beats per minute. However, adrenaline does not decrease the myocardial irritability. Rather, it increases the irritability or excitability of the myocardium, which can lead to arrhythmias or irregular heartbeats. Therefore, option (c) is incorrect.

The spleen is an important organ in the immune system and plays a vital role in the destruction of old and damaged red blood cells (RBCs). As RBCs age, they become less flexible and more prone to getting trapped in small blood vessels. The spleen filters out these damaged RBCs and removes them from circulation by phagocytosis. The phagocytosed RBCs are broken down and the components are recycled. The spleen also plays a role in storing and releasing platelets and white blood cells, and helps in the immune response to infections.

A person having blood group A indicates that the person has A antigen on the surface of their red blood cells (RBCs). This means that their immune system does not recognize A antigen as foreign, so they will not produce antibodies against it. People with blood group A can receive blood from individuals with blood groups A and O, but not from those with blood groups B or AB. Blood group A individuals can donate blood to people with blood groups A and AB. It is important to determine an individual's blood type before any blood transfusion or organ transplantation to prevent adverse immune reactions.

Blood group B is characterized by the presence of B antigen in the red blood cells. This antigen is responsible for the B blood group and is absent in the A blood group. The B antigen is a complex carbohydrate that is found on the surface of red blood cells. The immune system recognizes this antigen as foreign, and individuals with blood group B produce antibodies against the A antigen. This is why blood transfusions must be carefully matched to ensure that the recipient does not have an adverse immune reaction to the donor blood.

Extracellular fluid is a body fluid that exists outside of cells. It includes interstitial fluid, plasma, lymph, and transcellular fluid. The primary ions present in extracellular fluid are sodium (Na+) and chloride (Cl-), followed by bicarbonate (HCO3-) and calcium (Ca2+). Potassium (K+), on the other hand, is the primary ion found inside cells, with only a small amount present in extracellular fluids. The concentration of K+ in extracellular fluids is tightly regulated because even small changes can affect important physiological processes like muscle contractions and nerve impulses. Therefore, option A is the correct answer as it is not abundant in extracellular fluids.

The velocity of blood flow in vessels is determined by various factors, such as the caliber of the blood vessel, the viscosity of blood, and the pressure difference between two ends of the blood vessel. The caliber of the blood vessel determines the resistance to blood flow, and as the caliber of the vessel decreases, the resistance increases, which causes the velocity of blood flow to decrease. Blood viscosity is another factor that influences blood flow velocity, as increased viscosity can lead to reduced flow. Lastly, the pressure difference between two ends of the blood vessel also plays a crucial role in determining blood flow velocity, as a greater pressure difference between two ends results in a higher velocity of blood flow.

The heart is a muscular organ that pumps blood to various parts of the body. It is divided into four chambers, namely the right atrium, right ventricle, left atrium, and left ventricle. The left border of the heart is formed by the left atrium and left ventricle. This is because the left atrium is located superior and posterior to the left ventricle. The right ventricle is located anteriorly and forms the right border of the heart. The left atrium receives oxygenated blood from the lungs and pumps it into the left ventricle. The left ventricle then pumps the oxygenated blood into the aorta, which distributes it to the rest of the body.

Immunoglobulin G (IgG) is the only class of immunoglobulin that is capable of crossing the placenta from mother to fetus. This transfer of IgG antibodies from the mother provides passive immunity to the fetus and helps protect it against infections. The transfer of IgG across the placenta occurs mainly during the third trimester of pregnancy and continues after birth through breast milk. IgD, IgM, and IgE do not cross the placenta.

During the process of blood clotting, fibrinogen is converted into fibrin, a long, insoluble protein that forms a mesh-like network that helps to trap blood cells and form a clot. This process is initiated by the activation of prothrombin, a plasma protein, by the enzyme thrombin. Thrombin cleaves fibrinogen, releasing fibrinopeptides A and B, which allows fibrinogen to be polymerized into fibrin. The polymerization of fibrin is responsible for the formation of a stable blood clot.

Thrombus is a medical term used to refer to a blood clot that forms inside a blood vessel. It can occur due to various reasons such as injury, inflammation, or slow blood flow. When a thrombus forms, it can obstruct the blood flow, leading to serious complications such as stroke or heart attack. Thrombus can also break away from its original site and travel to other parts of the body, causing blockages and damage to organs. Therefore, prompt diagnosis and treatment of thrombus are crucial to prevent life-threatening complications.

The middle cardiac vein is a vein that runs along the posterior interventricular sulcus on the heart and drains blood from the back of the heart. However, it does not open directly into the right atrium like most veins in the heart. Instead, it empties into the larger coronary sinus, which then opens into the right atrium. The anterior cardiac vein drains the front of the heart and opens directly into the right atrium, while the superior vena cava drains blood from the upper body and also opens into the right atrium. Therefore, the correct answer is option A, the middle cardiac vein, as it does not open directly into the right atrium.

Blood platelets, also known as thrombocytes, are small, disc-shaped cells that are essential for blood clotting. When a blood vessel is damaged, platelets rush to the site of injury and stick to the damaged area, forming a plug to stop the bleeding. This process is called hemostasis and is crucial for preventing excessive blood loss. Platelets also release chemicals that attract other clotting factors to the site of injury, leading to the formation of a stable clot. Therefore, the primary function of platelets is to aid in the coagulation of blood.
While platelets play a role in the immune response by releasing chemicals that attract white blood cells to the site of infection or inflammation, they do not ingest bacteria. Additionally, platelets do not carry hemoglobin or transport CO2, which are functions performed by red blood cells.

The SA (sinoatrial) node, located in the right atrium, is known as the natural pacemaker of the heart, as it initiates the electrical impulse that leads to the contraction of the heart. From the SA node, the impulse spreads across the atria, causing them to contract. The impulse then reaches the AV (atrioventricular) node, which is located between the atria and ventricles. The AV node delays the impulse slightly to allow the atria to complete their contraction before the impulse is transmitted to the ventricles.
After the AV node, the impulse travels along the Bundle of His, which divides into the right and left bundle branches that extend down into the ventricles. The Purkinje fibers are specialized muscle fibers that rapidly transmit the electrical impulse throughout the ventricles, causing them to contract in a coordinated manner.
Therefore, the correct pathway for the propagation of the cardiac impulse is from the SA node to the AV node, then to the Bundle of His, and finally to the Purkinje fibers.

The pulmonary valve is located between the right ventricle and the pulmonary artery, and it prevents the backflow of blood from the pulmonary artery into the right ventricle. When the right ventricle contracts, the pulmonary valve opens, allowing blood to be pumped out of the heart and into the lungs. The pulmonary valve then closes when the right ventricle relaxes to prevent the backflow of blood. Therefore, option 4 is the correct answer.

The celiac trunk is the first major branch of the abdominal aorta and supplies blood to the foregut. The splenic artery arises from the celiac trunk and supplies blood to the spleen, as well as the stomach and pancreas. The superior mesenteric artery arises from the abdominal aorta just below the celiac trunk and supplies blood to the midgut, while the inferior mesenteric artery arises from the abdominal aorta just above the bifurcation into the common iliac arteries and supplies blood to the hindgut. The renal artery arises from the abdominal aorta just below the origin of the superior mesenteric artery and supplies blood to the kidneys.

Buffering agents are substances that help regulate the pH of body fluids by accepting or releasing hydrogen ions. In the human body, the main buffering systems are the bicarbonate buffer system, the phosphate buffer system, and the protein buffer system. Hemoglobin also acts as a buffer in blood. Carbohydrates, on the other hand, are not considered buffering agents in the body.

Blood grouping is the classification of blood based on the presence or absence of certain antigens on the surface of red blood cells. The most commonly used system for blood grouping is the ABO system, which categorizes blood into four types: A, B, AB, and O. The Rh factor is another important factor used in blood grouping. Blood transfusion is the process of transferring blood or blood products from one person to another. It is crucial that the blood type of the donor and the recipient match to prevent adverse reactions, which can be life-threatening. Hence, blood grouping is important for blood transfusion to ensure that the recipient receives compatible blood.