CVS 1: Circulatory System Overview

Circulatory System Overview

• Comprises heart and blood vessels, essential for blood transport to and from tissues.
• Functions include nutrient distribution, gas exchange (O2 and CO2), waste removal, hormone distribution, bleeding prevention, infection prevention, and temperature regulation.

Heart Structure

• Located in the thorax, above the diaphragm and slightly left; size comparable to a closed fist.
• Encased in a thin membrane called the pericardium.
• Divided into four chambers: right atrium, left atrium, right ventricle, and left ventricle, separated by interatrial and interventricular septa.

Heart Valves

• Atrioventricular (Cuspid) Valves:
  • Tricuspid valve: between right atrium and right ventricle.
  • Mitral valve: between left atrium and left ventricle.
• Semilunar Valves:
  • Aortic valve: at the aorta's origin.
  • Pulmonary valve: at the pulmonary trunk's start.

Types of Circulation

• Systemic Circulation: Blood flow between the heart and body cells.
  • Oxygenated blood is pumped from the left ventricle to the aorta, distributed via arteries, arterioles, and capillaries, and returns deoxygenated blood through venules and veins to the right atrium.
• Pulmonary Circulation: Flow between the heart and lungs.
  • Deoxygenated blood from the right atrium moves to the right ventricle, then to the lungs via pulmonary arteries for gas exchange, returning oxygenated blood to the left atrium.
• Portal Circulation: Blood flow between two capillary sets.
  • Venous blood from the digestive system is routed via the portal vein to the liver before returning to systemic veins.
• Coronary Circulation: Supplies blood to the heart muscle (myocardium).

Vascular System Components

• Arteries: Carry blood away from the heart, branching like trees, thick walls rich in smooth muscle and elastic fibers.
• Veins: Carry blood towards the heart, usually accompanied by arteries; thinner walls, possess valves, and have wider lumens.
• Capillaries: Microscopic networks between arterioles and venules, facilitating nutrient and gas exchange.

Differences Between Arteries and Veins

• Arteries transport oxygenated blood (excluding pulmonary arteries); veins carry deoxygenated blood (excluding pulmonary veins).
• Arterial walls are thick and non-comprisable; venous walls are thin and comprisable.
• Valves present in veins but absent in arteries.

Capillary Types

• Continuous: Uninterrupted endothelial lining, common in muscle and neural tissues.
• Fenestrated: Have pores, allowing greater permeability, found in kidneys and endocrine glands.
• Sinusoids: Irregular, larger diameter capillaries facilitating blood and fluid exchange, found in liver, spleen, and bone marrow.

Anastomosis

• Definition: Connection between neighboring vessels allowing blood flow alternatives.
• Types:
  • Arterial Anastomosis: Between arteries, particularly in joints, hands, feet, base of the brain, and abdominal region.

Clinical Significance

• Anastomoses are crucial for maintaining blood flow under varying conditions, essential in injury or vascular blockage situations.
• Understanding differences in vessel types aids in clinical assessments and interventions related to vascular health.

This quiz covers the fundamentals of the circulatory system, including the definitions and differences between arteries, veins, and capillaries. It also explores systemic and portal circulations, as well as the functions of the vascular system. Test your knowledge on these essential components and their relationships.