Topic 09: Transport in Animals

Transport in Humans

• The circulatory system consists of:

  • Blood vessels

  • A pump (the heart)

  • Valves to ensure one-way blood flow.

A. Blood (Pickering, S.2.25)

• 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.

Blood Cells and Their Functions

White Blood Cells

• Defense against diseases:

  • Lymphocytes: Produce antibodies.

  • Phagocytes: Ingest microorganisms (phagocytosis).

Red Blood Cells

• Characteristics:

  • Contain hemoglobin, which binds oxygen.

• Shape: Biconcave for increased surface area.

Platelets

• Function: Cause blood clotting.

• Characteristics: Irregular shape, no nucleus when mature.

Blood Vessels (Pickering, S.2.26)

Types of Blood Vessels:

1. 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

2. 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

3. 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

The Heart (Pickering, S.2.28)

Structure of the Heart

• 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.

Function of Major Blood Vessels:

• 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.

Heart Valves:

• 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).

Blood Circulation

Atria and 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.

Septum

• Separates deoxygenated blood on the right from oxygenated blood on the left.

Double Circulation

• 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.

Heart and Exercise

Changes During Exercise

• 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.

Heart Health Issues

• 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.

Prevention and Causes of CHD:

• 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.

Monitoring Heart Activity

1. ECG (Electrocardiogram):

   • Monitors electrical patterns through heart muscle; irregularities may indicate disease.

2. Pulse Rate Measurement:

   • Irregular pulse can signify heart issues.

3. Heart Sounds:

   • Normal ‘lub-dup’ sound indicates healthy valve function; irregular sounds can indicate leaks.

Vocabulary

• Key terms:

  • Platelets: cell fragments that aid in clotting.

  • Plasma: liquid component of blood.

  • Artery: vessel carrying blood away from the heart.

  • Vein: vessel carrying blood to the heart.

  • Capillary: tiny vessels for material exchange.

  • Valve: structures preventing backflow in vessels/heart.

  • Lumen: inside space of a vessel.

  • Aorta: largest artery in the body, distributing oxygenated blood.

  • Vena Cava: major vein returning deoxygenated blood.

  • Atrium: upper chambers of the heart.

  • Ventricle: lower chambers of the heart.

  • Septum: wall dividing left and right sides of the heart.

  • Double circulation: the separate paths for deoxygenated and oxygenated blood circulation.