Test: The Circulatory System - Class 10 MCQ

The superior vena cava is responsible for carrying deoxygenated blood from the upper parts of the body (head, neck, and arms) back to the right atrium of the heart. This is a critical part of the circulatory system, ensuring that blood can be re-oxygenated in the lungs.

Platelets, or thrombocytes, are crucial for blood clotting. When a blood vessel is injured, platelets aggregate at the site of the wound and release substances that help initiate the clotting process, forming a plug to prevent excessive bleeding.

White blood cells (WBCs) play a crucial role in the immune system by protecting the body from diseases. They achieve this through processes such as phagocytosis, where they engulf and digest harmful bacteria and foreign substances. This function is vital for maintaining health and combating infections.

The spleen acts as a blood reservoir and plays a key role in the immune response by producing lymphocytes, which are essential for fighting infections. It also helps remove old or damaged red blood cells from circulation, maintaining healthy blood composition.

The sino-atrial node, often referred to as the heart's natural pacemaker, generates electrical impulses that trigger the contraction of the heart muscles. This initiates the heartbeat and regulates the heart rate, coordinating the flow of blood throughout the body.

The hepatic portal system is responsible for transporting blood from the gastrointestinal tract and spleen to the liver. In the liver, excess nutrients can be stored, and toxins can be detoxified, making it a crucial part of metabolic regulation and waste processing in the body.

The "lub-dub" sound of the heart is caused by the opening and closing of the heart valves. The "lub" sound (first heart sound) is produced by the closure of the atrioventricular (AV) valves, while the "dub" sound (second heart sound) is produced by the closure of the semilunar valves. This rhythmic sound is an indicator of the heart's functioning.

Blood helps maintain a uniform body temperature by distributing heat generated by metabolic processes throughout the body. This thermoregulation is crucial for maintaining homeostasis and ensuring that all body systems function optimally.

Hemoglobin, found in red blood cells (RBCs), is the primary component responsible for transporting oxygen. It binds to oxygen in the lungs and releases it to tissues throughout the body. This process is essential for cellular respiration and energy production.

Hemoglobin is not a component of blood plasma; it is found within red blood cells. Blood plasma primarily consists of water, proteins, inorganic salts, and trace amounts of other substances. Plasma serves as the liquid medium for transporting cells, nutrients, and waste products throughout the body.

Diapedesis refers to the process by which white blood cells move through the walls of blood vessels to reach sites of infection or injury. This capability allows them to respond rapidly to pathogens and contribute to the body's immune defense mechanisms.

Systolic pressure refers to the maximum pressure in the arteries during the contraction of the heart, specifically when the ventricles pump blood into the aorta and pulmonary artery. It is a critical measurement used to assess cardiovascular health and is typically recorded as the higher number in a blood pressure reading.

Blood type O is considered the universal donor because it does not have A or B antigens on the surface of its red blood cells. This means that individuals with type O blood can donate to any other blood type without causing an immune reaction, making it invaluable in transfusions.

Lymphatic vessels play a crucial role in the circulatory system by returning excess tissue fluid, known as lymph, back to the bloodstream. This process helps maintain fluid balance in the body and is essential for the proper functioning of the immune system, as lymph carries white blood cells.

Capillaries are tiny blood vessels that connect arteries and veins. They play a vital role in facilitating the exchange of oxygen, carbon dioxide, nutrients, and waste products between the blood and surrounding tissues. This exchange is essential for cellular metabolism and overall health.

The term "pulse" refers to the rhythmic expansion and contraction of an artery's wall as blood is pumped through it during ventricular systole. This pulse can be felt at various points in the body and is an important indicator of heart rate and overall cardiovascular health.

The average lifespan of a red blood cell is approximately 120 days. After this period, RBCs are typically removed from circulation by the spleen and liver, where they are broken down, and their components are recycled for new blood cell production.

The Rh factor is significant in blood transfusions because if Rh-positive blood is transfused into an Rh-negative individual, the recipient's immune system may produce antibodies against the Rh factor. This can lead to a severe and potentially fatal immune reaction, making compatibility testing crucial before transfusions.

When hemoglobin binds with carbon monoxide, it forms carboxyhemoglobin, which significantly reduces hemoglobin's capacity to transport oxygen. This binding is extremely dangerous and can lead to carbon monoxide poisoning, as the body is deprived of oxygen.

Antibodies produced by certain types of white blood cells (especially lymphocytes) play a crucial role in the immune response by binding to and neutralizing pathogens such as bacteria and viruses. This action helps protect the body from infections.