Circulatory System

The circulatory system, also known as the cardiovascular system, is a vital network responsible for transporting nutrients, oxygen, hormones, and other essential substances throughout the body. It also removes waste products, like carbon dioxide, to be expelled. This intricate system is composed of the heart, blood vessels, and the blood itself.

Internal Structure of the Heart

The heart is a muscular organ that acts as a pump, circulating blood throughout the body. It is divided into four chambers that work to pump both oxygenated and deoxygenated blood.

• Valves: Flaps of tissue that prevent the backflow of blood. The four main valves are the tricuspid, pulmonary, mitral, and aortic valves.
• Septum: A wall of muscle that separates the right and left sides of the heart.
• Pacemaker: A small group of cells in the right atrium, called the sinoatrial (SA) node, that controls the heart rate.

Schematic Diagram of the Heart

[A simple diagram showing the four chambers (right and left atria, right and left ventricles), valves, and major blood vessels (aorta, pulmonary trunk, vena cava, pulmonary veins)]

Blood Vessels

These form a complex network to transport blood.

• Arteries: Thick-walled vessels that carry oxygenated blood away from the heart.
  • Aorta: The largest artery in the body.
  • Pulmonary Trunk: The artery that carries deoxygenated blood from the right ventricle to the lungs.
  • Coronary Artery: The artery that supplies blood to the heart muscle.
• Veins: Vessels that carry deoxygenated blood back to the heart.
  • Coronary Vein: The vein that drains blood from the heart muscle.
  • Vena Cava: The largest vein in the body.
• Capillaries: Tiny vessels that connect arteries and veins, facilitating the exchange of oxygen, nutrients, and waste products.

Circulation of Blood

• Double Circulation: A circulatory system in which the blood travels twice through the heart for each complete circuit of the body.
  • Pulmonary Circulation: This circuit moves deoxygenated blood from the heart to the lungs, where it picks up oxygen and releases carbon dioxide. The now oxygen-rich blood returns to the heart.
  • Systemic Circulation: In this circuit, the heart pumps oxygenated blood to the rest of the body. After delivering oxygen and nutrients, the deoxygenated blood returns to the heart to begin the cycle again.

Blood

This fluid consists of red and white blood cells, plasma, and platelets. It carries oxygen, nutrients, and waste products.

Blood Groups

• A, B, AB, and O: The four main blood groups, determined by the presence or absence of certain antigens on the surface of red blood cells.
• Universal Donor: A person with blood group O, who can donate blood to a person with any other blood group.
• Universal Acceptor: A person with blood group AB, who can receive blood from a person with any other blood group.

Conditions Related to the Functioning of the Heart

• Palpitations: A noticeably rapid, strong, or irregular heartbeat due to agitation, exertion, or illness.
• Cardiac Arrest: A sudden, unexpected loss of heart function, breathing, and consciousness.
• Hypertension: High blood pressure, which can damage blood vessels and lead to other cardiovascular problems.
• Atherosclerosis: The hardening of arteries due to the buildup of plaque, which can restrict blood flow.
• Heart Attack: Occurs when blood flow to the heart is blocked, often by a blood clot.
• Stroke: Happens when blood flow to the brain is interrupted, either by a blockage or a ruptured blood vessel.
• Heart Failure: A condition where the heart can't pump blood as effectively as it should.
• Arrhythmia: An irregular heartbeat, which can be too fast, too slow, or erratic.

Lymphatic System

• Introduction: A network of tissues and organs that help rid the body of toxins, waste and other unwanted materials. The lymphatic system is a part of the circulatory system and the immune system.