i. white blood cells
Answer: White blood cells (leukocytes) are part of the immune system. They defend the body against pathogens by engulfing and destroying them (phagocytosis) or by producing antibodies (lymphocytes).
2. Differentiate between:
Answer: Blood is a connective tissue composed of plasma (55%) and formed elements (45% - RBCs, WBCs, platelets). Serum is the liquid portion of blood that remains after blood has clotted. Serum is essentially plasma without clotting factors.
Answer: Arteries carry blood away from the heart, have thick elastic walls, narrow lumens, and no valves. Veins carry blood toward the heart, have thin walls, wider lumens, and valves to prevent backflow.
Answer: The tricuspid valve is located between the right atrium and right ventricle and has three cusps. The bicuspid (mitral) valve is between the left atrium and left ventricle and has two cusps.
Answer: Systole is the phase of the cardiac cycle when the heart muscle contracts, pumping blood out of the chambers. Diastole is the phase when the heart muscle relaxes, allowing the chambers to fill with blood.
e. Red blood cells and white blood cells
Answer: Red blood cells (erythrocytes) are numerous, biconcave, lack a nucleus, and contain hemoglobin for oxygen transport. White blood cells (leukocytes) are fewer, have a nucleus, and function in immunity and defense.
3. Why a circulatory system necessary?
Answer: A circulatory system is necessary because it transports essential substances throughout the body. It delivers oxygen and nutrients to cells and removes waste products like carbon dioxide and urea. It also transports hormones, immune cells, and heat. In large, multicellular organisms, diffusion alone is insufficient to meet the metabolic demands of cells, so a specialized transport system is required. The circulatory system ensures homeostasis and supports all life processes.
4. Name the different types of blood vessels.
Answer: The three main types of blood vessels are:
1. Arteries: Carry blood away from the heart.
2. Veins: Carry blood toward the heart.
3. Capillaries: Microscopic vessels where exchange of gases, nutrients, and waste occurs between blood and tissues.
5. Describe coronary circuit.
Answer: The coronary circuit is the system of blood vessels that supplies blood to the heart muscle itself. The coronary arteries arise from the base of the aorta and branch to supply oxygenated blood to the myocardium. The cardiac veins collect deoxygenated blood and drain into the coronary sinus, which empties into the right atrium. This circuit is essential for the heart's own metabolism.
6. Write the functions of blood.
Answer: Blood performs several vital functions:
Transport: Carries oxygen, nutrients, hormones, and waste products.
Regulation: Helps regulate body temperature, pH, and water balance. Protection: White blood cells and antibodies defend against infection; platelets prevent blood loss through clotting.
7. What are the organs that are connected to the circulatory system?
Answer: The circulatory system is connected to almost all organs. Key organs include:
Heart: The pump. Lungs: For gas exchange. Kidneys: For filtration and waste removal. Liver: For metabolism and detoxification. Intestines: For nutrient absorption. Brain: For regulation and oxygen supply.
8. Name the type of blood vessels. (Refer to Question 4)
9. What are the types of white blood cells? Why are these called white blood cells?
Answer: The main types of white blood cells are granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes). They are called "white" blood cells because they lack hemoglobin and appear colorless or whitish when separated from red blood cells in a centrifuge.
10. What are the functions of the human heart?
Answer: The human heart acts as a double pump. The right side pumps deoxygenated blood to the lungs (pulmonary circulation),
and the left side pumps oxygenated blood to the body (systemic circulation). It ensures unidirectional blood flow through valves and maintains blood pressure.
11. Why valves are present in veins not in arteries?
Answer: Valves are present in veins to prevent the backflow of blood. Blood in veins flows under low pressure, so valves ensure it moves toward the heart. Arteries carry blood under high pressure from the heart, so valves are not needed to prevent backflow.
12. What happens if an injury that cut open artery is much more dangerous than an injury to vein?
Answer: An injury to an artery is more dangerous because arterial blood is under high pressure and flows rapidly. A cut artery can lead to rapid and severe blood loss (hemorrhage) that is difficult to control, potentially causing shock and death. Venous bleeding is slower and easier to control.
13. Why is the muscular of the left ventricle thicker than that of right ventricle?
Answer: The muscular wall of the left ventricle is thicker because it must generate high pressure to pump blood to the entire body through the systemic circulation. The right ventricle only pumps blood to the lungs, which requires less pressure.