Circulatory System

Main Parts of the Circulatory System

The circulatory system (also known as the cardiovascular system) is responsible for transporting blood, nutrients, oxygen, carbon dioxide, and hormones throughout the body.

1. Heart: A muscular organ that pumps blood throughout the body.
2. Blood: The fluid that carries oxygen, nutrients, and waste products.
3. Blood Vessels: A network of tubes (arteries, veins, capillaries) that carry blood throughout the body.

Process of Circulation in the Body

Blood circulates continuously throughout the body, delivering oxygen and nutrients to cells and removing waste products.

• Oxygenated blood (rich in oxygen) leaves the heart through arteries and travels to all parts of the body.
• In the capillaries (tiny blood vessels), oxygen and nutrients are exchanged with cells, and carbon dioxide and waste products are picked up.
• Deoxygenated blood (rich in carbon dioxide) returns to the heart through veins.
• The heart then pumps this deoxygenated blood to the lungs, where carbon dioxide is released and oxygen is picked up.
• The newly oxygenated blood returns to the heart, and the cycle repeats.

Components of Blood

Blood is a complex fluid made up of several components:

1. Plasma:
   • Function: The yellowish liquid component of blood in which blood cells are suspended. It carries nutrients, hormones, proteins, and waste products.
2. Blood Cells:
   • Red Blood Cells (RBCs) / Erythrocytes:
     • Function: Contain hemoglobin, a protein that binds to oxygen, transporting oxygen from the lungs to the body tissues and carbon dioxide from the tissues back to the lungs.
   • White Blood Cells (WBCs) / Leukocytes:
     • Function: Part of the immune system, they fight infections and other diseases.
   • Platelets / Thrombocytes:
     • Function: Small, irregular-shaped cell fragments that play a crucial role in blood clotting to stop bleeding.

Types of Blood Groups

Human blood is classified into different groups based on the presence or absence of specific antigens on the surface of red blood cells. The four main ABO blood groups are:

• A
• B
• AB
• O

Blood Pressure

Concept: Blood pressure is the force exerted by circulating blood against the walls of the body's arteries, the major blood vessels. It is usually measured as systolic pressure (when the heart beats) over diastolic pressure (when the heart rests between beats).

Heartbeat and Pulse

• Heartbeat: The rhythmic contraction and relaxation of the heart muscles that pumps blood throughout the body. A normal adult heart beats 60 to 100 times per minute.
• Pulse: The throbbing sensation felt in arteries (like in the wrist or neck) due to the rhythmic contraction and relaxation of the heart. It corresponds to the heartbeat.

Keeping the Heart Healthy

• Through Exercise: Regular physical activity strengthens the heart muscle, improves blood circulation, and helps maintain a healthy weight.
• Through Good Food Habits: Eating a balanced diet rich in fruits, vegetables, whole grains, and lean proteins, while limiting saturated fats, trans fats, cholesterol, sodium, and added sugars, helps prevent heart disease.