Transport in Animals - In-Depth Notes

Transport in Animals

Overview of the Circulatory System

• Components of the Circulatory System:
  • Heart: Acts as a pump to circulate blood.
  • Blood Vessels: Networks of tubes for blood flow including arteries, veins, and capillaries.
  • Valves: Ensure one-way flow of blood to prevent backflow.

Learning Objectives

• Understanding the circulatory system functionality.
• Explaining single vs. double circulation.
• Discussing the advantages of double circulation in mammals.

Blood Flow Dynamics

• Blood flows in one direction due to valves.
• The heart contains 4 chambers:
  • Right Atrium & Right Ventricle: Receive deoxygenated blood and pump it to the lungs.
  • Left Atrium & Left Ventricle: Receive oxygenated blood from the lungs and pump it to the body.

Oxygenation Process

• Blood becomes oxygenated in the lungs when it picks up oxygen and releases carbon dioxide.
• After being oxygenated, blood is transported to various body tissues.

Types of Circulation

Single Circulation (Fish)

• Blood passes through the heart once per circuit:
  • Blood flows to the gills where it gets oxygenated and then to the body.

Double Circulation (Mammals, Birds, Reptiles)

• Blood passes through the heart twice per circuit:
  • Pulmonary Circulation: Blood travels to the lungs and back to the heart.
  • Systemic Circulation: Blood is pumped to the rest of the body.
• Allows higher efficiency in oxygen transport due to separation of oxygenated and deoxygenated blood.

Advantages of Double Circulation

• Maintains higher pressure to send blood further.
• Separated oxygenated and deoxygenated blood enhances efficiency in delivering oxygen to cells.
• Enables rapid exchange of gases like oxygen and carbon dioxide.

Structure of the Heart

• Comprised of:
  • Atria: Upper chambers that receive blood.
  • Ventricles: Lower chambers that pump blood.
  • Septum: Divides right and left sides of the heart to prevent mixing of oxygenated and deoxygenated blood.
• Muscle Thickness:
  • Ventricles have thicker walls than atria to pump blood under higher pressure (left ventricles more muscular).

Heart Functionality

• Systole: Contraction phase where the heart pumps blood out.
• Diastole: Relaxation phase allowing chambers to fill with blood.
• Valves ensure unidirectional flow during these phases (e.g., Mitral Valve, Tricuspid Valve).

Coronary Arteries & Heart Health

• Coronary arteries supply oxygenated blood to the heart muscle. Blockage can cause heart disease.
• Risk Factors for Coronary Heart Disease (CHD):
  • Poor Diet: High in saturated fat, leading to cholesterol build-up.
  • Smoking: Nicotine causes vasoconstriction, increasing blood pressure.
  • Stress: Chronic stress can elevate blood pressure.
  • Obesity: Excess weight can strain the heart.
  • Genetic Predisposition: Family history can increase risk.
  • Age & Gender: Men generally at higher risk than women.

Blood Composition

• Components of Blood:
  • Red Blood Cells: Transport oxygen using hemoglobin.
  • White Blood Cells: Part of the immune system, protect against pathogens (phagocytes engulf pathogens, lymphocytes produce antibodies).
  • Platelets: Assist in clotting to prevent excessive bleeding.
  • Plasma: Liquid component, carries nutrients, hormones, and waste products.

Function of Blood Components

• Red Blood Cells: Deliver oxygen to body cells, utilize hemoglobin for gas transport.
• White Blood Cells: Defend against infections via phagocytosis and antibody production.
• Platelets: Form clots to stop bleeding and prevent infection from wounds.

Blood Vessels' Structure & Function

• Arteries: Thick, elastic walls adapt to high pressure; do not have valves due to continuous forward blood flow.
• Veins: Thinner walls, valves prevent backflow; transport deoxygenated blood back to the heart.
• Capillaries: One-cell thick for efficient exchange of materials between blood and tissues.

The Lymphatic System

• Function: Returns excess tissue fluid to the cardiovascular system and filters lymph through lymph nodes.
• Plays a crucial role in immune response by producing lymphocytes.

Summary of the Circulatory Process

• Blood cycles from heart → arteries → capillaries (exchange occurs) → veins → heart. Oxygen and nutrients delivered while waste products are removed.