Double Circulation in Humans

Overview

• Double Circulation: The path in which blood flows is called a circuit. Humans have a double circuit heart with two main pathways for blood flow:
  • Pulmonary Circuit: Between the heart and lungs.
  • Systemic Circuit: Between the heart and the rest of the body.

Pulmonary Circuit

• Purpose: Transports deoxygenated blood to the lungs and brings back oxygenated blood to the heart.
• Process:
  1. Deoxygenated blood enters the right atrium.
  2. Blood is sent to the right ventricle.
  3. The right ventricle pumps the blood to the lungs.
  4. In the lungs, blood becomes oxygenated.
  5. Oxygenated blood returns to the left atrium via pulmonary veins.
  6. Blood is then sent to the left ventricle for systemic circulation.

Systemic Circuit

• Purpose: Supplies oxygenated blood to the body and collects deoxygenated blood.
• Process:
  1. Oxygenated blood is pumped from the left ventricle into the systemic aorta.
  2. The aorta distributes blood to various body organs.
  3. Deoxygenated blood from organs is collected by the inferior and superior vena cavae.
  4. Blood returns to the right atrium.
• Function: Provides nutrients, oxygen, and other substances to tissues, and removes carbon dioxide and other waste products.

Hepatic Portal System

• Unique Connection: Between the digestive tract and liver.
• Process:
  • The hepatic portal vein carries nutrient-rich blood from the intestines to the liver before it enters systemic circulation.

Coronary Circulation

• Special System: Dedicated vessels for blood flow to and from the heart's musculature, ensuring its proper function.