Topic 09: Transport in Animals

The circulatory system consists of:
- Blood vessels
- A pump (the heart)
- Valves to ensure one-way blood flow.

Components of Blood:
- Red Blood Cells (RBCs): Carry oxygen via hemoglobin.
- White Blood Cells (WBCs): Defense against disease.
- Platelets: Responsible for blood clotting.
- Plasma: Liquid part of blood that transports:
  - Soluble nutrients: glucose, amino acids, lipids, vitamins, mineral ions.
  - Wastes: urea, carbon dioxide.
  - Blood proteins: albumin, antibodies.
  - Hormones: insulin, glucagon, adrenaline.

Defense against diseases:
- Lymphocytes: Produce antibodies.
- Phagocytes: Ingest microorganisms (phagocytosis).

Arteries
- Speed & Direction: Fast; from heart to organs.
- Function: Deliver oxygen and nutrients to body cells.
- Characteristics: Thick, elastic(伸縮), and muscular walls.
- Pressure: High pressure.
- Valves: Absent except in aorta and pulmonary artery.
- Lumen: Narrower
Veins
- Speed & Direction: Slowest; from organs to heart.
- Function: Carry away waste products.
- Characteristics: Thinner walls, larger lumen.
- Pressure: Very low.
- Valves: Present to prevent backflow.
- Lumen: Large
Capillaries
- Speed & Direction: Slower; joins arteries and veins.
- Function: Exchange of materials between blood and tissue.
- Characteristics: One-cell thick; very large total surface area.
- Pressure: Low pressure.
- Valves: Absent.
- Lumen: Very narrow

Composed of various chambers and valves:
- Right Atrium: Receives deoxygenated blood from vena cava.
- Right Ventricle: Pumps deoxygenated blood to the lungs via the pulmonary artery.
- Left Atrium: Receives oxygenated blood from the lungs via the pulmonary vein.
- Left Ventricle: Pumps oxygenated blood to the body via the aorta.

Vena Cava: Returns deoxygenated blood from the body to the right atrium.
Pulmonary Artery: Carries deoxygenated blood from the right ventricle to the lungs.
Pulmonary Vein: Returns oxygenated blood from the lungs to the left atrium.
Aorta: Distributes oxygenated blood to all body tissues except the lungs.

Function: Prevent backflow of blood and ensure proper direction.
Key Valves: Tricuspid valve (between right atrium and ventricle), Bicuspid valve (between left atrium and ventricle), Semilunar valves (at exit of ventricles).

Atria:
- Receive blood from veins.
- Pump blood into ventricles.
Ventricles:
- Thicker muscular walls than atria to pump blood further.
- Left ventricle has the thickest wall to overcome body resistance.

Right side receives deoxygenated blood from the body, pumps it to lungs for oxygenation.
Left side receives oxygenated blood from lungs, pumps it to the rest of the body. This flow is completed twice during one cycle.

Increased energy requirement leads to:
- Faster heartbeats.
- Arteries dilate to increase blood flow.
- Increased oxygen and glucose supply for respiration.
- Efficient removal of carbon dioxide.

Coronary Heart Disease (CHD):
- Coronary arteries supply blood to heart muscles but can be narrowed by fatty materials or clots, leading to heart damage and potential heart attacks.

Causes:
- Diet high in saturated fat and cholesterol.
- Lack of exercise.
- Smoking and stress.
Prevention:
- Balanced diet rich in fruits and vegetables.
- Regular exercise.
- Avoiding smoking.

ECG (Electrocardiogram):
- Monitors electrical patterns through heart muscle; irregularities may indicate disease.
Pulse Rate Measurement:
- Irregular pulse can signify heart issues.
Heart Sounds:
- Normal ‘lub-dup’ sound indicates healthy valve function; irregular sounds can indicate leaks.