Chapter: 06. Human Circulatory System
Section A: Multiple Choice Questions
Section B: Fill in the Blanks
Section C: True/False Questions
False (Pulmonary arteries carry deoxygenated blood) False (Blood group O has no antigens) Section D: Explanation of Terms
Pulse: The rhythmic throbbing movements felt in arteries, caused by the pumping action of the heart. Antigen: Special proteins found on the surface of red blood cells that determine a person’s blood group. Blood Transfusion: The process of transferring blood from one person (donor) to another (recipient). Enucleated: A term describing cells that lack a nucleus, such as mature red blood cells in mammals. Cardiac Cycle: The complete sequence of events, including contraction (systole) and relaxation (diastole), that occurs during one single heartbeat. Section E: Short Answer Questions
Any three of the following: It transports digested food and oxygen to every cell of the body. It removes carbon dioxide from cells and transports it to the lungs. It removes wastes from the cells and takes them to the kidneys. It helps in regulating body temperature. It protects the body against infections. It transports hormones to all body parts. It helps in clotting of blood and healing of wounds. Veins have valves to prevent the backflow of blood, ensuring that blood flows only towards the heart, especially when moving against gravity. The four chambers of the human heart are the right auricle (atrium), left auricle (atrium), right ventricle, and left ventricle. The “lub” sound occurs when the ventricles contract and the cuspid valves close. The “dub” sound occurs when the pulmonary and aortic (semilunar) valves close. A healthy adult can donate blood every 56 days. Section F: Diagram-Based Question
A: Artery, B: Vein, C: Capillary Vessel A (artery) has thick and muscular walls, while vessel B (vein) has thinner walls. The main function of vessel C (capillary) is the exchange of food, oxygen, carbon dioxide, and wastes between the blood and body cells. Section G: Long Answer Questions
Deoxygenated blood from the body first enters the right auricle through large veins called vena cava. From the right auricle, it passes through the tricuspid valve into the right ventricle. When the right ventricle contracts, it pumps this deoxygenated blood into the pulmonary artery, which then carries the blood to the lungs for purification (oxygenation). Having a healthy lifestyle and specific food habits is crucial for heart health because it helps manage factors like blood pressure, cholesterol levels, and weight. Eating fruits, vegetables, and fish rich in omega-3 fatty acids provides essential nutrients and fiber, while avoiding sugary, fried, and high-cholesterol foods reduces the risk of plaque buildup in arteries. Regular exercise strengthens the heart muscle, and avoiding smoking and excessive alcohol prevents damage to blood vessels, all contributing to a strong and efficient circulatory system. Section H: Identifying and Differentiate Concepts
Oxygen transport: Red Blood Cells (RBCs)
Fights infection: White Blood Cells (WBCs) Systolic Blood Pressure: This is the highest pressure exerted by the blood on artery walls when the ventricles contract and pump blood out of the heart.
Diastolic Blood Pressure: This is the lowest pressure exerted by the blood on artery walls when the ventricles relax and the heart fills with blood. Section I: Everyday Use/Critical Thinking
Your pulse rate increases during physical activities like running because your muscles need more oxygen and nutrients to produce energy. The heart beats faster and pumps more blood per minute to deliver this increased supply and remove waste products more quickly, meeting the higher demands of your active body. Arteries are located deeper in the body because they carry blood directly from the heart under very high pressure. Their deep position protects them from external injury, which could cause severe and rapid blood loss. Veins, on the other hand, carry blood under much lower pressure back to the heart, so they are often closer to the surface and are less risky to access for medical procedures like drawing blood. 
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