1. The functions of the circulatory system include:
- Transportation of oxygen, nutrients, hormones, and waste products throughout the body.
- Regulation of body temperature by distributing heat throughout the body.
- Protection against diseases and infections through the immune response.
- Maintenance of fluid balance by regulating the movement of fluids between cells, tissues, and organs.
2. Components of a circulatory system:
- Heart: The muscular organ that pumps blood throughout the body.
- Blood: A fluid connective tissue consisting of red blood cells, white blood cells, platelets, and plasma.
- Blood vessels: Tubular structures that carry blood throughout the body. They include arteries, veins, and capillaries.
3. Types of blood cells:
- Red blood cells (erythrocytes): Carry oxygen from the lungs to the body tissues and remove carbon dioxide.
- White blood cells (leukocytes): Play a significant role in the immune system, defending the body against infections and diseases.
- Platelets (thrombocytes): Responsible for blood clotting to prevent excessive bleeding.
4. The heart is a muscular organ located in the chest cavity, slightly to the left of the midline. It is positioned between the lungs and rests on the diaphragm. It is protected by the ribcage and surrounded by the pericardial sac.
5. Different kinds of white blood cells:
- Neutrophils: They are the most abundant type and play a crucial role in the initial immune response to bacterial infections.
- Lymphocytes: There are two main types: T cells and B cells. T cells regulate the immune response, while B cells produce antibodies.
- Monocytes: They help to remove dead cells and foreign particles from the body.
- Eosinophils: Involved in allergic reactions and defense against parasitic infections.
- Basophils: Release chemicals involved in allergic reactions and inflammation.
6. The pericardial membranes consist of three layers:
- Fibrous pericardium: The tough outer layer that protects and anchors the heart.
- Parietal pericardium: The middle layer that lines the fibrous pericardium.
- Visceral pericardium (also called the epicardium): The inner layer that covers the surface of the heart.
7. Chambers of the heart:
- Right atrium: Receives deoxygenated blood from the body.
- Right ventricle: Receives blood from the right atrium and pumps it to the lungs for oxygenation.
- Left atrium: Receives oxygenated blood from the lungs.
- Left ventricle: Receives blood from the left atrium and pumps it to the rest of the body.
8. Cardiac cycle: It refers to the sequence of events that occur during one heartbeat. It consists of the contraction (systole) and relaxation (diastole) of the atria and ventricles, allowing blood to flow through the heart.
9. The function of capillaries is to facilitate the exchange of oxygen, nutrients, and waste products between the blood and the surrounding tissues. Capillaries have thin walls that allow substances to pass through, such as oxygen and nutrients into the tissues and carbon dioxide and waste products into the blood.
10. Pathways of circulation:
- Systemic circulation: The pathway in which oxygenated blood from the left ventricle is pumped through the aorta to deliver oxygen and nutrients to the body tissues. Deoxygenated blood returns to the right atrium through the superior and inferior vena cava.
- Pulmonary circulation: The pathway in which deoxygenated blood from the right atrium is pumped to the lungs via the pulmonary arteries to pick up oxygen and release carbon dioxide. Oxygenated blood returns to the left atrium through the pulmonary veins.
