Circulatory System Lecture Notes

Overview

• The circulatory system in vertebrates involves the heart, blood vessels, and blood.
• It includes the cardiovascular system, comprising the heart and blood vessels.
• There are two main divisions: systemic circulation and pulmonary circulation.
• The system is often closed in vertebrates, meaning blood circulates within vessels.

Circulatory System Components

Heart

• Pumps blood around the body, providing oxygen and nutrients.
• Four chambers: left atrium, left ventricle, right atrium, right ventricle.

Blood

• Composed of plasma, red blood cells, white blood cells, platelets.
• Transports oxygen, nutrients, and waste.

Blood Vessels

• Three types: arteries, veins, and capillaries.
• Arteries: Carry oxygenated blood away from the heart.
• Veins: Carry deoxygenated blood to the heart.
• Capillaries: Microscopic vessels where exchange with tissues occurs.

Circulatory Circuits

Pulmonary Circulation

• Carries deoxygenated blood from the right heart to the lungs and returns oxygenated blood to the left heart.

Systemic Circulation

• Delivers oxygenated blood from the left heart to the body and returns deoxygenated blood to the right heart.
• Subdivided into macrocirculation and microcirculation.

Lymphatic System

• Complements the circulatory system.
• Transports lymph and aids the immune system.
• Open system, unlike the closed circulatory system.

Additional Circulatory Routes

• Coronary Circulation: Supplies the heart muscle itself.
• Cerebral Circulation: Supplies the brain.
• Renal Circulation: Supplies the kidneys.
• Bronchial Circulation: Supplies the lungs.

Disorders of the Circulatory System

• Cardiovascular Diseases: Include atherosclerosis, heart defects, clots.
• Investigations: Use of angiography, MRI, and other imaging techniques.

Evolution of the Circulatory System

• Originated over 600 million years ago, evolving from simple to complex systems.
• Closed systems in vertebrates allow efficient blood distribution.

Historical Perspective

• Ancient Egyptians, Greeks, and others had early but incomplete understanding.
• Ibn al-Nafis and William Harvey made significant contributions to understanding circulation.