Blood Composition and Functions Quiz

Erythrocytes and Blood Characteristics

• Erythrocytes, or red blood cells, primarily function to transport oxygen from the lungs to body tissues and return carbon dioxide from tissues to the lungs.
• Blood is characterized by its viscosity, pH level, temperature, and color, reflecting its oxygen content.
• Most blood cells originate in the bone marrow from hematopoietic stem cells.

Plasma and Blood Color

• The main contributor to osmotic pressure in plasma is albumin, a protein that regulates fluid balance in blood.
• Blood appears bright red when it has a high oxygen content due to the binding of oxygen to hemoglobin.

Lifespan of Blood Components and Heart Valve Function

• Most formed elements, such as erythrocytes and leukocytes, typically survive in the bloodstream for days to several months, depending on the type.
• When the atrioventricular (AV) valves are open, blood flows freely from the atria to the ventricles.

Heart Function and Pressures

• Papillary muscles and chordae tendineae prevent backflow into the ventricles when they are relaxed, ensuring one-way blood flow.
• An increase in intraventricular pressure signals the closing of the AV valves and the opening of the semilunar valves, allowing blood to exit the heart.

Coronary Circulation and Circuits

• Coronary circulation is responsible for supplying blood to the heart muscle itself, providing oxygen and nutrients critical for muscular function.
• The main difference between the pulmonary and systemic circuits is that the pulmonary circuit carries deoxygenated blood to the lungs, while the systemic circuit delivers oxygenated blood to the rest of the body.

Anastomoses and Arterial Supply

• Anastomoses in coronary circulation are mainly responsible for providing alternative pathways for blood flow to ensure adequate perfusion even if one route is blocked.
• The left anterior descending artery supplies the interventricular septum, anterior ventricular walls, left atrium, and posterior wall of the left ventricle.

Heart Valves and Arrhythmias

• The pulmonary semilunar valve prevents backflow into the right ventricle after deoxygenated blood exits to the pulmonary artery.
• An ectopic focus, such as an area of tissue in the atria, can trigger irregular heart rhythms by generating electrical impulses independently of the sinoatrial node.