Transport in Human Note 2024_Student

Parts and Functions of the Circulatory System

• Blood Components:

  • Red Blood Cells: Contain hemoglobin for oxygen transport.

  • Plasma: Transports blood cells, ions, hormones, and waste.

  • White Blood Cells: Involved in phagocytosis and antibody formation.

  • Platelets: Initiate blood clotting through fibrin formation.

• Heart: Pumps blood through a network of vessels.

• Coronary Heart Disease: Characterized by the occlusion of coronary arteries due to unhealthy factors.

Learning Outcomes

Candidates should be able to:

1. Identify major blood vessels to/from heart and organs.

2. Relate vessel structures (arteries, veins, capillaries) to their functions.

3. Describe blood components and their roles.

4. Understand heart structure and valve function.

5. Explain coronary heart disease and its preventive measures.

Need for a Transport System

• Unicellular Organisms: Directly exchange materials via diffusion due to high surface area-to-volume ratio.

• Multicellular Organisms: Require a transport system due to:

  • Inefficient diffusion over longer distances.

  • Need for rapid exchange of nutrients and waste among deep cells.

Human Circulatory System Overview

• Comprises: 1 Heart and Blood Vessels (Arteries, Veins, Capillaries).

• Blood circulates through two systems: Pulmonary (to/from lungs) and Systemic (to/from body).

• Double Circulation: Blood flows through heart twice per cycle, allowing efficient oxygen transport.

Main Functions of Double Circulation

1. Maintains higher blood pressure for efficient organ supply.

2. Separates oxygenated and deoxygenated blood for optimal gas exchange.

Blood Vessels

Structure and Function

• Arteries: Thicker walls, carry oxygenated blood away from the heart under high pressure.

• Veins: Thinner walls, contain valves, carry deoxygenated blood back to the heart under lower pressure.

• Capillaries: Thin walls (one cell thick) for substance exchange via diffusion.

Adaptations of Blood Vessels to Function

• Arteries: Elastic walls to withstand pressure and maintain flow.

• Veins: Valves prevent backflow; skeletal muscles assist blood return.

• Capillaries: Large surface area to enhance diffusion, slow blood flow for efficient exchange.

Red Blood Cell (RBC) Characteristics

• Function: Transport oxygen as oxyhemoglobin.

• Shape: Biconcave for increased surface area.

• Lifespan: Approximately 127 days; destroyed in spleen.

White Blood Cells (WBC) Types and Functions

1. Phagocytes: Engulf pathogens via phagocytosis.

2. Lymphocytes: Produce antibodies for immunity.

Blood Components Summary

• Plasma: 55% of blood; transports nutrients, wastes, and maintains body temperature.

• Red Blood Cells: 45%; vital for oxygen transport.

• White Blood Cells and Platelets: Essential for defense and clotting mechanisms.

The Human Heart Structure and Function

• Atria: Receives blood; pumps into ventricles.

• Ventricles: Pumps blood to lungs and body.

• Valves: Ensure unidirectional blood flow.

• Contraction: Cardiac muscles allow continuous pumping without fatigue.

Pathway of Blood Through the Heart

1. Oxygen-poor blood enters through venae cavae to right atrium.

2. Blood travels to right ventricle, sent to lungs via pulmonary arteries.

3. Oxygen-rich blood returns to left atrium via pulmonary veins, then to left ventricle.

4. Finally, pumped to the body through aorta.

Coronary Heart Disease (CHD)

• Causes: Build-up of fat (atherosclerosis) leading to narrowing of arteries and possible heart attacks.

• Risk Factors: Poor diet, lack of exercise, smoking.

• Preventive Measures: Healthy diet, regular exercise, and avoiding smoking.

• Treatment Options: Include angioplasty, stenting, bypass surgery, and medications to manage risk.