Transport in Animals

Overview

• Focus on higher-level content related to the circulatory system in animals.
• Involves arteries, veins, capillaries, blood pressure, and transport mechanisms.

Circulatory System Organization

• Arteries: Carry blood at high pressure away from the heart.
• Veins: Return blood at low pressure to the heart.
• Capillaries: Site of diffusion between blood and tissues.
  • High Pressure: Forces blood plasma to form tissue fluid containing oxygen, glucose, ions.
  • Diffusion: Oxygen and glucose diffuse into cells; CO2 diffuses out.

Transport Mechanisms

• Passive Diffusion: Utilized by oxygen.
  • Moves from high to low concentration without energy.
• Glucose Transport: Often involves sodium-glucose co-transporters.
  • Indirect passive transport using sodium ion concentration gradients.
• Carbon Dioxide: Moves out of cells via passive diffusion following concentration gradients.

Lymphatic System

• 15% of Tissue Fluid: Drains into the lymphatic system, becomes lymph.
• Lymph System: Another transport mechanism beyond cardiovascular system.

Circulatory Systems in Mammals

• Double Circulation: Heart has two sides, creating different loops for high and low pressure.
  • High pressure for body circulation.
  • Low pressure for lung circulation.
• Heart Structure:
  • Blood leaves heart to body under high pressure.
  • Returns to heart deoxygenated, goes to lungs, then back to heart.

Human Heart Structure

• Four Chambers: Two atria, two ventricles.
• Right Side: Deoxygenated blood, pulmonary circulation.
  • Right Atrium to Right Ventricle: Through atrioventricular valves.
  • Pulmonary Artery: To lungs, semi-lunar valves.
• Left Side: Oxygenated blood, systemic circulation.
  • Left Atrium to Left Ventricle: Through atrioventricular valves.
  • Aorta: To body, semi-lunar/aortic valves.

Heart Function

• Atria & Ventricles: Contract to move blood, separate functions for each side.
• Valves: Prevent backflow, maintain unidirectional flow.
• Pacemaker: SA node initiates heartbeat; AV node coordinates contraction.

Cardiac Cycle

• Cycle Duration: ~70 times per minute.
• Systole & Diastole: Contraction and relaxation phases.
  • Systole: Atria contract, ventricles contract separately.
  • Diastole: Relaxation phase allows filling.
• Pressure Dynamics:
  • Ventricles have higher pressure than atria.
  • Arteries maintain high pressure to ensure continuous blood flow.

Key Concepts

• Understanding material movement in and out of cells.
• Role of concentration gradients in transport.
• Importance of high pressure in systemic circulation and low pressure in pulmonary circulation.
• Lymphatic system as an auxiliary transport system.