The respiratory areas of the medulla oblongata and pons are influenced by a number of factors that cause modifications in the rate and depth of breathing. Factors involved in involuntary control are detected by sensory receptors, which forward nerve impulses to the DRG. Higher brain centers involved in voluntary control send nerve impulses to the [...]
Alveolar Gas Exchange During alveolar gas exchange, respiratory gases are exchanged between the air in the alveoli and the blood in the capillaries that surround them. Oxygen and carbon dioxide must diffuse through the respiratory membrane, which is composed of the squamous cells forming an alveolar wall and the squamous cells forming a capillary wall. [...]
The RBCs play a major role in the transport of both oxygen and carbon dioxide. Oxygen Transport In the lungs, oxygen diffuses from the air in alveoli into the blood of surrounding capillaries. Most of the oxygen enters RBCs and combines with the heme portions of hemoglobin (Hb) to form oxyhemoglobin (HbO2). About 98.5% of [...]
Inflammatory Disorders Chronic obstructive pulmonary disease (COPD) is a group of disorders in which there is a long-term obstruction that reduces airflow to and from the lungs. The two most important COPDs are chronic bronchitis and emphysema. Bronchitis is inflammation of the bronchi, and it is characterized by excessive mucus production that partially obstructs air [...]
Both males and females possess mammary glands. The mammary glands of males and immature females are similar. At puberty, estrogens and progesterone stimulate the development of female mammary glands. Estrogens start breast and mammary gland development, and progesterone stimulates the maturation of the mammary glands so that they are capable of secreting milk. Another hormone [...]
Pregnancy Disorders Eclampsia (e-klamp'-se-ah), or toxemia of pregnancy, is a disorder that occurs in two forms. Preeclampsia of late pregnancy is characterized by increased blood pressure, edema, and proteinuria (protein in the urine). The cause is unknown. If unsuccessfully treated, it may develop into eclampsia, a far more serious disorder that may lead to convulsions [...]
Respiration or pulmonary ventilation, is the process that exchanges air between the atmosphere and the alveoli of the lungs. Air moves into and out of the lungs along an air pressure gradient-from regions of higher pressure to regions of lower pressure. There are three pressures that are important in breathing: Atmospheric pressure is the pressure [...]
The lungs receive the entire output of the right ventricle. Consequently, pulmonary blood flow is equal to cardiac output, about 5 L/min. The normal transit time for blood through the pulmonary capillaries is about 0.75 seconds. Gas equilibration between the alveolar air and the pulmonary capillary takes about 0.25 seconds for O2 and about 0.05 [...]
THE PRIMARY ROLE of the respiratory system is to make oxygen available to cells for cellular respiration and to remove carbon dioxide, the main byproduct of that metabolism. The entire process of respiration encompasses five unique and sequential processes: Breathing (pulmonary ventilation)-the movement of air into and out of the lungs. Alveolar gas [...]
Healthy adults average 12 to 15 quiet breathing cycles per minute. A breathing cycle is one inspiration followed by one expiration. The volume of air inhaled and exhaled in a quiet or forceful breathing cycle varies with size, sex, age, and physical condition. The average respiratory volumes have been determined by size, age, and sex [...]