Human Circulatory System Quiz

Human Circulatory System

• The circulatory system, also known as the blood vascular system, comprises the heart, blood vessels, and blood.

Heart Structure

• The heart is a mesodermally-derived, muscular organ located in the thoracic cavity, between the lungs, slightly angled to the left.
• It has a fist-sized dimension and is encased in a protective, double-walled sac called the pericardium, containing pericardial fluid.
• The heart has four chambers: two atria (smaller upper chambers) and two ventricles (larger lower chambers).
• The atria and ventricles on the same side of the heart are separated by a septum.
  • Interatrial septum: separates the right and left atria (thin)
  • Interventricular septum: separates the right and left ventricles (thick)
  • Atrioventricular septum: a thick fibrous tissue between atria and ventricles on the same side.
• Each septum has an opening connecting the corresponding chambers.
• Valves govern blood flow direction.
  • Tricuspid valve: three cusps, guards the opening between the right atrium and right ventricle.
  • Bicuspid or mitral valve: two cusps, guards the opening between the left atrium and left ventricle.
  • Semilunar valves: located at the openings of the pulmonary artery (right ventricle) and aorta (left ventricle). They ensure one-way blood flow from the ventricles to the arteries preventing backflow.