⚡ Quick Revision: The Transport System
The Circulatory System is the body's transport network, responsible for moving nutrients, gases, and waste products to and from cells.
Circulatory System: Consists of the Heart, Blood Vessels (Arteries, Veins, Capillaries), and Blood.
Functions of the Circulatory System
- ✔ Transport: Carries Oxygen from lungs to tissues and CO₂ from tissues to lungs.
- ✔ Protection: Transports white blood cells to fight infections and platelets to clot blood.
- ✔ Regulation: Helps in maintaining body temperature and distributing hormones.
⚡ Quick Revision: Components of Blood
Plasma: The straw-colored liquid portion of blood, making up about 55% of its volume, containing water, salts, and proteins.
The Formed Elements (Cells)
| Cell Type | Scientific Name | Main Function |
|---|---|---|
| Red Blood Cells | Erythrocytes | Carry oxygen via Hemoglobin. |
| White Blood Cells | Leukocytes | Defense against germs/infections. |
| Platelets | Thrombocytes | Help in Blood Clotting. |
Mature Red Blood Cells in humans do not have a nucleus. This provides more space for hemoglobin to carry oxygen!
⚡ Quick Revision: The Human Heart
The heart is a muscular pumping organ, roughly the size of a closed fist, located in the chest cavity between the lungs.
Structure of the Heart
- ✔ Four Chambers: Divided into two upper Atria (receiving chambers) and two lower Ventricles (pumping chambers).
- ✔ Septum: A muscular wall that prevents the mixing of oxygenated and deoxygenated blood.
- ✔ Valves: Flaps that ensure blood flows in only one direction and prevent backflow.
The Right side of the heart deals with deoxygenated blood (to lungs), while the Left side deals with oxygenated blood (to body).
⚡ Quick Revision: Blood Vessels
Blood Vessels: A network of hollow tubes that transport blood throughout the entire body.
Types of Blood Vessels
| Feature | Arteries | Veins | Capillaries |
|---|---|---|---|
| Direction | Away from Heart. | Towards the Heart. | Connect Arteries to Veins. |
| Blood Type | Oxygenated (except Pulmonary). | Deoxygenated (except Pulmonary). | Exchange of gases/nutrients. |
| Walls | Thick and elastic. | Thin with Valves. | Extremely thin (one-cell thick). |
Arteries do not have valves because blood flows under high pressure. Veins have valves to prevent the backflow of blood as it moves under low pressure.
⚡ Quick Revision: Heartbeat, Pulse & BP
Heartbeat: One complete contraction (systole) and relaxation (diastole) of the heart muscles. An average adult heart beats 72 to 80 times per minute.
Key Measurement Concepts
- ✔ Pulse: The rhythmic throbbing of arteries as blood is pumped through them. It is most easily felt at the wrist (radial artery).
- ✔ Blood Pressure: The force exerted by circulating blood against the walls of the arteries. Measured using a Sphygmomanometer.
- ✔ Stethoscope: An instrument used by doctors to listen to the "lub-dub" sounds of the heart.
Remember that your pulse rate is equal to your heart rate. Physical exercise increases both as the body requires more oxygen and energy.
⚡ Quick Revision: Healthy Heart & Hygiene
Lifestyle choices directly impact the efficiency of the heart and the health of blood vessels.
Factors Affecting Heart Health
- ✔ Diet: Excessive intake of fats and fried foods can lead to Cholesterol buildup in arteries.
- ✔ Exercise: Regular physical activity strengthens cardiac muscles and improves blood flow.
- ✔ Rest: Proper sleep is essential for the body to repair tissues and regulate blood pressure.
Common Cardiovascular Issues
1. Hypertension: High blood pressure that can damage the heart and kidneys.
2. Anemia: A condition where the blood lacks enough healthy red blood cells or hemoglobin.
3. Obesity: Excess body fat that puts additional strain on the heart.