🧱 Cells, Tissues, Organs and Systems
🔗 Organisation in Living Organisms
- Cells: Basic building blocks of life
- Tissues: Groups of similar cells working together (e.g. muscle tissue)
- Organs: Made of different tissues performing a function (e.g. stomach)
- Organ systems: Groups of organs working together (e.g. digestive system)
🍔 The Digestive System
🧪 Enzymes
- Biological catalysts – Speed up reactions without being used up
- Made of proteins, affected by temperature and pH (can become denatured)
⚙️ Types of Enzymes:
- Amylase (carbohydrase): Starch → Sugar (e.g. maltose)
– Made in salivary glands, pancreas, small intestine - Protease: Proteins → Amino acids
– Made in stomach, pancreas, small intestine - Lipase: Lipids → Fatty acids + Glycerol
– Made in pancreas, small intestine
🧴 Bile
- Made in liver, stored in gall bladder
- Neutralises stomach acid (alkaline)
- Emulsifies fats (breaks them into small droplets for better enzyme action)
❤️ The Circulatory System
🫀 The Heart
- Double circulatory system – Blood passes through the heart twice per circuit
- Right side: Pumps deoxygenated blood to lungs
- Left side: Pumps oxygenated blood to body
Heart Structure:
- 4 chambers: Right/Left Atrium, Right/Left Ventricle
- Valves – Prevent backflow
- Pacemaker – Controls heartbeat rate (natural or artificial)
🩸 Blood Vessels
- Arteries – Carry blood away from heart, high pressure, thick walls
- Veins – Carry blood to the heart, valves to stop backflow
- Capillaries – Tiny, exchange substances (e.g. oxygen, CO₂)
🩸 Components of Blood
- Red blood cells – Carry oxygen (contain haemoglobin)
- White blood cells – Fight infection
- Platelets – Help blood clot
- Plasma – Liquid that carries everything (cells, glucose, urea, hormones etc.)
🦠 Non-Communicable Diseases
💔 Cardiovascular Disease (CVD)
- Coronary arteries become blocked by fatty deposits
- Leads to heart attacks or strokes
Treatments:
- Stents – Tubes to keep arteries open
- Statins – Drugs that reduce cholesterol
- Artificial hearts – Temporary solution
- Heart valves – Replaced if leaky or stiff
📈 Risk Factors
- Lifestyle: Smoking, diet, alcohol, lack of exercise
- Genetic: Inherited conditions
- Examples:
- Smoking → lung disease, cancer
- Alcohol → liver + brain damage
- Poor diet → obesity, diabetes
🎗️ Cancer
- Uncontrolled cell growth
- Benign: Non-cancerous, stays in one place
- Malignant: Spreads, dangerous
- Caused by mutations, can be genetic or environmental
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