Circulatory System

Overview of the Circulatory System in Animals

• Purpose: Essential for transporting supplies and wastes throughout the body.

  • Transportation Functions:

    • Delivers fuel (sugars) acquired from the digestive system.

    • Supplies oxygen obtained from the respiratory system.

    • Removes wastes generated from metabolic processes.

Blood and Blood Cells

• Blood Composition: Blood is a specialized tissue comprised of fluid and cells.

  • Plasma: The liquid component of blood, containing dissolved salts, sugars, proteins, and other substances.

  • Red Blood Cells (RBC): Contain hemoglobin, responsible for transporting oxygen.

  • White Blood Cells (WBC): Play crucial roles in defense and immunity against pathogens.

Anatomy of the Circulatory System

• Main Components:

  • Heart: The organ that pumps blood through the circulatory system.

  • Blood Vessels: Tubular structures that carry blood throughout the body.

    • Types of Blood Vessels:

      • Arteries: Carry blood away from the heart.

      • Veins: Return blood to the heart.

      • Capillaries: Microscopic vessels where exchange occurs between blood and tissues.

The Vertebrate Heart

• Structure:

  • Four-Chambered Heart:

    • Atria (two): Thin-walled chambers that collect blood.

    • Ventricles (two): Thick-walled chambers that pump blood out.

  • Heart Valves: Flaps of tissue that prevent backflow of blood.

    • Chambers: Right atrium, left atrium, right ventricle, left ventricle.

Electrical Conduction in the Heart

• The heart's pumping action is controlled by electrical impulses.

  • Atria Contract: Empty completely before ventricles contract.

  • Ventricles Contract: Stimulated from bottom to top, driving blood into arteries.

  • Electrocardiogram (EKG): Electrical signals can be detected on the skin, providing a measure of heart activity.

Blood Vessels

• Arteries:

  • Carry blood away from the heart at high pressure.

  • Have thicker walls for strength and elasticity.

• Veins:

  • Return blood to the heart at lower pressure.

  • Thinner-walled and have one-way valves to prevent backflow.

Major Arteries and Veins

• Arteries:

  • Pulmonary Artery: Carries blood to the lungs.

  • Aorta: Main artery supplying blood to the body.

  • Carotid Artery: Supplies blood to the head.

• Veins:

  • Pulmonary Vein: Returns oxygenated blood from lungs.

  • Superior Vena Cava: Blood from upper body.

  • Inferior Vena Cava: Blood from lower body.

Comparison: Veins vs. Arteries

• Veins:

  • Thin-walled with little pressure.

  • Assisted by skeletal muscle contractions for movement of blood.

  • Contain valves preventing backflow.

• Arteries:

  • Thick-walled, under constant pressure.

  • Use pressure to move blood away from the heart to capillaries.

Capillaries

• Structure and Function:

  • Very thin walls to facilitate diffusion.

  • Allow exchanges of oxygen, carbon dioxide, nutrients, and wastes between blood and body cells.

Blood Flow Pathways

• Pulmonary Circuit:

  • Right ventricle pumps deoxygenated blood to the lungs via pulmonary arteries.

  • Blood picks up oxygen and releases carbon dioxide before returning to the left atrium.

• Systemic Circuit:

  • Oxygenated blood is pumped from the left ventricle through the aorta to the rest of the body.

  • Returns deoxygenated blood via superior and inferior venae cavae to the right atrium.

Key Stops in Circulatory System

• Lungs: Pick up oxygen and remove carbon dioxide.

• Small Intestine: Absorb nutrients from digested food.

• Large Intestine: Recover water from digested food.

• Liver: Processes nutrients and detoxifies substances.

• Kidneys: Filter out wastes, excess salts, and water from the blood.

• Bone: Produces new red blood cells.

• Spleen: Produces and recycles white blood cells.

Circulatory System and Homeostasis

• Homeostasis: The body's ability to maintain internal balance.

  • Balancing oxygen and nutrient intake with waste removal.

  • Exercise: Increases heart rate; demands more ATP and efficiency in waste removal.

  • Disease Impact: Affects oxygen and energy balance within the body.