Respiratory System Quiz

Respiratory System: Oxygen and Carbon Dioxide Transport

• Increase in resistance can be due to right-sided heart failure or pulmonary embolism
• Blood is redirected to other alveoli when resistance increases in the affected alveoli
• Oxygen diffuses from endothelial cells to smooth muscle cells, leading to vasodilation
• Hemoglobin carries oxygen in two ways: bound to hemoglobin and dissolved in plasma
• Hemoglobin is composed of 4 polypeptide chains, each bound to an iron-containing heme group
• Oxyhemoglobin is the hemoglobin-oxygen combination, while reduced hemoglobin is deoxyhemoglobin
• The rate at which hemoglobin binds or releases oxygen is regulated by several factors
• Carbon dioxide is transported in blood in three forms: dissolved in plasma, chemically bound to hemoglobin, and as bicarbonate ions
• Carbon dioxide readily binds with hemoglobin in the tissues with lower PCO2
• Reactions to convert carbon dioxide to bicarbonate ions mostly occur inside red blood cells
• The Haldane effect reflects the ability of reduced hemoglobin to form carbaminohemoglobin and buffer H+
• Factors like temperature, PCO2, H+, or BPG levels in blood influence hemoglobin's affinity for oxygen, affecting oxygen unloading from the blood

Fetal Circulatory System and Hemoglobin

• The large umbilical vein carries oxygenated blood from the placenta to the embryo's body, where most of it enters the ductus venosus, bypassing the liver.
• Blood from the ductus venosus and hepatic veins empties into the inferior vena cava, mixing with deoxygenated blood from the fetus' lower body before reaching the heart.
• The fetal liver's blood flow is minimal, with the mother's body processing nutrients for the fetus.
• Shunt systems allow blood to bypass the non-functional fetal lungs, with the foramen ovale allowing blood to flow directly from the right atrium to the left atrium.
• The ductus arteriosus transfers most blood directly into the aorta, bypassing the lungs, which receive adequate oxygen for growth.
• Deoxygenated blood from the aorta eventually reaches the umbilical arteries, returning to the placenta.
• Fetal hemoglobin (Hb F) has a higher affinity for oxygen than adult hemoglobin (Hb A) due to differences in subunit composition, crucial for effective oxygen transfer from the mother to the fetus.
• Alveoli are the main sites of gas exchange, consisting of type 1 and type 2 alveolar cells, with surfactant reducing surface tension and contributing to innate immunity.
• Alveolar pores equalize air pressure, allowing alternate air routes to collapsed alveoli.
• Gas exchange in alveoli is driven by the partial pressures of oxygen and carbon dioxide, with alveolar ventilation rate being a key index of effective ventilation.
• Optimal gas exchange requires a close match between ventilation and perfusion, with autoregulatory mechanisms controlling both processes.
• Ventilation and perfusion are controlled by changes in bronchiolar diameter and blood vessel resistance, ensuring efficient oxygen and carbon dioxide exchange in the lungs.

Respiratory System Anatomy and Function

• The pharynx is divided into three regions: nasopharynx, oropharynx, and laryngopharynx, each with different types of epithelium.
• The epiglottis is an elastic cartilage flap that covers the trachea during swallowing to prevent choking.
• The larynx, or voice box, contains vocal folds that vibrate to produce sound and is supported by cartilage.
• The trachea is a long tube made of C-shaped hyaline cartilage and lined with mucus-producing epithelium and cilia to trap contaminants.
• The bronchi, primary and secondary, contain cartilage rings that become more widely spaced as they branch into smaller bronchioles.
• The lungs have different lobes and are composed of spongy tissues containing alveoli, where gas exchange occurs with capillaries.
• The pleura is a double-layered serous membrane that covers the lungs and lines the thoracic cavity, containing lubricating fluid to decrease friction.
• The respiratory system is divided into upper and lower parts, as well as conducting and respiratory zones for air movement and gas exchange.
• Lung ventilation involves inspiration, where the diaphragm descends and rib cage rises, and expiration, where the diaphragm rises and rib cage descends.
• Boyle's Law explains the relationship between pressure and volume of gases, which is relevant to respiratory pressure changes during ventilation.
• The bronchial circuit involves changes in pressure and volume, with atmospheric pressure being a key reference point for respiratory pressure measurements.
• Different respiratory pressures, such as intrapulmonary pressure, intrapleural pressure, and transpulmonary pressure, are important for understanding lung mechanics.