organisation overview

1. Organisation Principles

🔹 What is organisation?

• The body is made up of cells → tissues → organs → organ systems → whole organisms.

🔹 Definitions:

• Cell: Basic building block.

• Tissue: Group of similar cells working together (e.g. muscle tissue).

• Organ: Made of different tissues working together (e.g. heart).

• Organ system: Group of organs working together (e.g. digestive system).

2. Digestive System

🔹 Purpose:

• Breaks down large insoluble molecules into small soluble molecules for absorption.

🔹 Organs and Functions:

3. Enzymes

🔹 What are enzymes?

• Biological catalysts – speed up reactions without being used up.

• Made of proteins.

🔹 How enzymes work:

• Lock and key model – enzyme has a specific active site for a specific substrate.

🔹 Enzyme Conditions:

• Work best at optimum temperature and pH.

• Too hot = enzyme denatures (active site changes shape).

• Too acidic/alkaline = enzyme may also denature.

🔹 Digestive Enzymes:

🔹 Bile:

• Not an enzyme.

• Emulsifies fats (breaks them into droplets) to increase surface area for lipase.

• Neutralises stomach acid for enzymes in small intestine.

4. The Heart and Blood

🔹 The Heart:

• Double circulatory system:

  • Right side: pumps deoxygenated blood to lungs.

  • Left side: pumps oxygenated blood to body.

🔹 Structure:

• 4 chambers: right & left atria, right & left ventricles.

• Valves prevent backflow.

• Coronary arteries supply oxygen to the heart muscle.

🔹 Pacemaker:

• Natural pacemaker in right atrium controls heartbeat.

• Artificial pacemakers are used if it fails.

5. Blood Vessels

6. Blood Components

7. Health and Disease

🔹 Health:

• State of physical and mental well-being.

• Communicable = caused by pathogens (e.g. flu).

• Non-communicable = not infectious (e.g. cancer, heart disease).

🔹 Risk Factors:

• Lifestyle (e.g. diet, smoking, alcohol, lack of exercise).

• Environment (e.g. pollution).

• Genetics.

8. Cancer

• Caused by uncontrolled cell division.

• Benign tumour: stays in one place, not cancerous.

• Malignant tumour: spreads to other parts – cancer.

• Risks: genetics, smoking, obesity, UV, viruses.

9. Plant Tissues and Organs

🔹 Leaf Structure:

🔹 Transpiration:

• Loss of water from leaves through stomata.

• Pulled up through xylem.

• Faster in: hot, dry, windy, bright conditions.

🔹 Translocation:

• Movement of sugars in phloem, to growing and storage areas.