Circulatory System

The circulatory system, also known as the cardiovascular system, functions as the body's intricate transportation network. At its core is the heart, a muscular pump with four chambers: two atria and two ventricles. Blood, carrying oxygen, nutrients, hormones, and waste products, flows through a network of blood vessels. Arteries carry oxygen-rich blood away from the heart, while veins return oxygen-poor blood back to the heart. The smallest blood vessels, capillaries, facilitate the exchange of substances between the blood and body tissues. Oxygen and nutrients diffuse from capillaries into tissues, while waste products like carbon dioxide move from tissues into capillaries to be carried away.

This dynamic process fuels the body's functions and supports its various systems. The heart's rhythmic contractions propel the blood, and the circulatory system collaborates with the respiratory system, where oxygen is inhaled and carbon dioxide is exhaled, maintaining a delicate balance. Ultimately, the circulatory system ensures the delivery of vital resources and the removal of waste, enabling the body to thrive and maintain equilibrium. 

The circulatory system is responsible for the transport of substances through the blood either to be used by cells or for their elimination. The circulatory system depends on the proper functioning of various organs to maintain its effectiveness. 

• Blood: Blood is a crucial component of the circulatory system. It consists of red blood cells, white blood cells, platelets, and plasma. Red blood cells carry oxygen from the lungs to body tissues and transport carbon dioxide back to the lungs for exhalation. White blood cells play a vital role in the immune response, defending the body against infections. Platelets are essential for blood clotting, preventing excessive bleeding. Plasma is the liquid portion of blood that carries nutrients, hormones, and waste products. 

• Heart: The heart is the central organ of the circulatory system, serving as a muscular pump that propels blood throughout the body. The heart's rhythmic contractions maintain the circulation of blood, ensuring the delivery of oxygen, nutrients, and hormones to tissues while removing waste products like carbon dioxide. 

• Lungs: While not a part of the circulatory system per se, the lungs are closely linked to it. The pulmonary circulation involves the movement of blood between the heart and lungs. In the lungs, oxygen is taken up by red blood cells and carbon dioxide is released into the air through exhalation. 

• Spleen: The spleen is an organ involved in the immune response and the filtering of blood. It helps remove damaged red blood cells and stores platelets. Additionally, the spleen can release stored blood in case of emergency situations, such as significant blood loss. 

• Kidneys: The kidneys play a role in maintaining proper blood pressure and fluid balance. They filter waste products and excess substances from the blood, which are then excreted as urine. The circulatory system delivers blood to the kidneys for filtration and nutrient exchange. 

• Liver: The liver is responsible for detoxifying the blood and processing nutrients absorbed from the digestive system. It produces important proteins that help regulate blood clotting and maintain blood volume. 

• Endocrine Glands: Various endocrine glands, such as the thyroid gland, adrenal glands, and pancreas, secrete hormones that influence the function of the circulatory system. These hormones can affect heart rate, blood vessel constriction, and other factors that impact circulation.

• Alpha globin protein: A component of haemoglobin that helps carry oxygen in red blood cells. 

• Arteries: Blood vessels that carry oxygenated blood away from the heart to various body tissues. 

• ATP: Adenosine triphosphate, a molecule that stores and releases energy within cells. 

• Autoantibodies: Antibodies produced by the immune system that target the body's own tissues. 

• B Cells: White blood cells responsible for producing antibodies and participating in the immune response.

• Beta globin protein: A component of haemoglobin involved in oxygen transport within red blood cells. 

• Blood: The vital fluid that transports nutrients, oxygen, waste products, and cells throughout the body. 

• Blood cells: Cellular components of blood, including red blood cells, white blood cells, and platelets. 

• Blood clotting: The process by which blood forms a gel-like clot to prevent excessive bleeding. 

• Blood flow: The movement of blood through the circulatory system to deliver nutrients and oxygen.

• Blood pressure: The force exerted by blood against the walls of blood vessels. 

• Blood vessels: Tubular structures that transport blood, including arteries, veins, and capillaries.

• Bloodstream: The flowing blood within the circulatory system. 

• Cancer cells: Abnormal cells that can grow and spread uncontrollably, forming tumours. 

• Cell function: The specific activities a cell carries out to maintain its survival and contribute to the body's overall functions. 

• Cell growth: The process by which cells increase in size and mass. 

• Cell membrane: A semipermeable barrier that encloses the contents of a cell and regulates the passage of substances. 

• Cell oxidation: A chemical reaction involving the transfer of electrons within cells, often producing energy. 

• Cells: The basic units of life, each performing specific functions in the body.

• Cellular division: The process of a cell splitting into two daughter cells, as in mitosis or meiosis. 

• Cellular function: The roles and activities that cells perform to maintain bodily functions. 

• Cellular metabolism: The set of chemical reactions that occur within cells to maintain life.

• Cholesterol: A lipid molecule essential for cell membranes and a precursor to hormones. 

• Coenzyme A: A molecule crucial for various biochemical reactions, including the breakdown of fats and carbohydrates. 

• Cytokines: Signalling proteins that regulate immune responses and cell communication. 

• DNA: Deoxyribonucleic acid, the genetic material that encodes information for cell development and function.

• Double circulation: The circulation of blood through the heart twice in a single complete cycle (pulmonary and systemic circuits). 

• Endothelial: Pertaining to the inner lining of blood vessels.

• Free radicals: Reactive molecules that can cause cellular damage.

• G6PD enzyme: Glucose-6-phosphate dehydrogenase, an enzyme important for protecting red blood cells from oxidative stress. 

• Genes: Units of DNA that contain instructions for building and maintaining cells and organisms. 

• Haemoglobin: The protein in red blood cells that binds to oxygen for transport. 

• Haemoglobin S: Abnormal haemoglobin variant responsible for sickle cell disease. 

• Inflammatory cells: White blood cells involved in immune responses against infections and injuries. 

• Membrane: A thin, flexible layer that surrounds cells or organelles, separating internal and external environments. 

• Osteocalcin: A protein hormone involved in bone mineralization and regulation of energy metabolism. 

• Plasma: The liquid component of blood containing water, electrolytes, hormones, and proteins. 

• Platelets: Small cell fragments involved in blood clotting and wound healing. 

• Red blood cells: Blood cells that transport oxygen using haemoglobin. 

• RNA: Ribonucleic acid, a molecule involved in protein synthesis and gene expression. 

• Simple circulation: The circulation of blood through the heart once in a single complete cycle (single circulation). 

• T Cells: White blood cells that play a central role in the immune response. 

• Type B cells: Lymphocytes responsible for producing antibodies in the immune response. 

• Valves: Structures in veins and the heart that prevent backflow of blood. 

• Veins: Blood vessels that carry deoxygenated blood back to the heart. 

• Vessel wall: The tissue layers composing the walls of blood vessels. 

• White blood cells: Cells of the immune system that defend against infections and foreign substances.

• X chromosome: One of the sex chromosomes determining the genetic sex of an individual.