Ch. 22 The Respiratory System
Describe the pleura of the lungs and their function
Pleura of the lungs is a serous membrane that helps protect the lungs. The functions of the pleura is to produce pleural fluid and create cavities that separate the major organs.
Propose reasons for fetal breathing movements
food, mother activity, the environment around her
Major functions of the respiratory system
provide oxygen to body tissues for cellular respiration, remove the waste product carbon dioxide, and help to maintain acid-base balance.
List the steps involved in pulmonary ventilation
inspiration and expiration
Discuss the process of acclimatization
is the process of adjustment that the respiratory system makes due to chronic exposure to a high altitude.
Describe the effect of exercise on the respiratory system
respiratory centers of the brain may be stimulated through the activation of motor neurons that innervate muscle groups that are involved in the physcila activity
Discuss the factors that can influence the respiratory rate
-Hypothalamus (The hypothalamus and other regions associated with the limbic system are involved in regulating respiration in response to emotions, pain, and temperature.) -Blood Levels (The peripheral chemoreceptors are responsible for sensing large changes in blood oxygen levels.) -Hydrogen ions (Depending on if there is an increase or decrease will determine if there will be removal of CO2 or more lactic acid build up) -Carbon dioxide ( Affects the chemical receptors that are located in the brain)
Compare the composition of atmospheric air and alveolar air
-The composition of air in the atmosphere and in the alveoli differs. In both cases, the relative concentration of gases is nitrogen > oxygen > water vapor > carbon dioxide. -The amount of water vapor present in alveolar air is greater than that in atmospheric air. -In addition, alveolar air contains a greater amount of carbon dioxide and less oxygen than atmospheric air.
Describe the effect of high altitude on the respiratory system
At high altitudes, a greater proportion of molecules of oxygen are released into the tissues. Secondly, at high altitudes, a greater amount of BPG is produced by erythrocytes, which enhances the dissociation of oxygen from hemoglobin.
Describe the principles of oxygen transport
As oxygen diffuses across the respiratory membrane from the alveolus to the capillary, it also diffuses into the red blood cell and is bound by hemoglobin. The following reversible chemical reaction describes the production of the final product, oxyhemoglobin (Hb-O2), which is formed when oxygen binds to hemoglobin. Oxyhemoglobin is a bright red-colored molecule that contributes to the bright red color of oxygenated blood.
List the structures that make up the respiratory system
Conduction Zone: -The nose and adjacent structures -Pharynx -Larynx -Trachea -Bronchial Tree Respiratory Zone: -Alveoli -(bronchioles) -(alveolar ducts)
Explain how the lungs inflate after birth
First the inhalation happens within 10 seconds after birth and not only serves as the first inspiration, but also acts to inflate the lungs.
Describe the structure of hemoglobin
Hemoglobin: protein structure composed of sub-units known as Quaternary 4 sub-units in a ring like fashion with iron atom covalently bound to the heme in the center of each sub-unit.
Define the terms Hyperpnea and Hyperventilation
Hyperpnea: Hyperpnea is an increased depth and rate of ventilation to meet an increase in oxygen demand as might be seen in exercise or disease, particularly diseases that target the respiratory or digestive tracts. Hyperventilation: hyperventilation is an increased ventilation rate that is independent of the cellular oxygen needs and leads to abnormally low blood carbon dioxide levels and high (alkaline) blood pH.
Describe the process of internal respiration
Internal respiration is gas exchange that occurs at the level of body tissues (Figure). Similar to external respiration, internal respiration also occurs as simple diffusion due to a partial pressure gradient. However, the partial pressure gradients are opposite of those present at the respiratory membrane. The partial pressure of oxygen in tissues is low, about 40 mm Hg, because oxygen is continuously used for cellular respiration. In contrast, the partial pressure of oxygen in the blood is about 100 mm Hg. This creates a pressure gradient that causes oxygen to dissociate from hemoglobin, diffuse out of the blood, cross the interstitial space, and enter the tissue. Hemoglobin that has little oxygen bound to it loses much of its brightness, so that blood returning to the heart is more burgundy in color. Considering that cellular respiration continuously produces carbon dioxide, the partial pressure of carbon dioxide is lower in the blood than it is in the tissue, causing carbon dioxide to diffuse out of the tissue, cross the interstitial fluid, and enter the blood. It is then carried back to the lungs either bound to hemoglobin, dissolved in plasma, or in a converted form. By the time blood returns to the heart, the partial pressure of oxygen has returned to about 40 mm Hg, and the partial pressure of carbon dioxide has returned to about 45 mm Hg. The blood is then pumped back to the lungs to be oxygenated once again during external respiration.
Define respiratory rate
Respiratory rate is the total number of breaths, or respiratory cycles, that occur each minute.
Discuss the meaning of respiratory volume and capacities
Respiratory volume is the term used for various volumes of air moved by or associated with the lungs at a given point in the respiratory cycle. Respiratory capacity is the combination of two or more selected volumes, which further describes the amount of air in the lungs during a given time.
Outline the mechanisms behind the control of breathing
The brain is behind the control of breathing, which are stimulated by pH changes and chemical changes in the blood.
Describe the principles of carbon dioxide transport
The first mechanism of carbon dioxide transport is by blood plasma, as some carbon dioxide molecules dissolve in the blood. The second mechanism is transport in the form of bicarbonate (HCO3-), which also dissolves in plasma. The third mechanism of carbon dioxide transport is similar to the transport of oxygen by erythrocytes.
Discuss the importance if sufficient ventilation and perfusion, and how the body adapts when they are insufficient
The importance of sufficient ventilation and perfusion is the high rate oxygen that enters the alveoli and the partial pressure of oxygen in the alveoli remains high. When the body is receiving insufficient of ventilation and perfusion, the body redirects the blood flow to alveoli that are receiving sufficient ventilation.
Describe the mechanisms that drive breathing
The intra-alveolar and intrapleural pressures are dependent on certain physical features of the lung. However, the ability to breathe—to have air enter the lungs during inspiration and air leave the lungs during expiration—is dependent on the air pressure of the atmosphere and the air pressure within the lungs.
Describe the overall function of the lung
The main function of the lungs is to perform the exchange of oxygen and carbon dioxide with air from the atmosphere.
Describe the respiratory centers of the medulla oblongata and the pons
The medulla oblongata contains the dorsal respiratory group (DRG) and the ventral respiratory group (VRG). The DRG is involved in maintaining a constant breathing rhythm by stimulating the diaphragm and intercostal muscles to contract, resulting in inspiration. The VRG is involved in forced breathing. Pons: The pons, called the pontine respiratory group, and consists of the apneustic and pneumotaxic centers. -The apneustic center is a double cluster of neuronal cell bodies that stimulate neurons in the DRG, controlling the depth of inspiration, particularly for deep breathing. -The pneumotaxic center is a network of neurons that inhibits the activity of neurons in the DRG, allowing relaxation after inspiration, and thus controlling the overall rate.
Discuss the process of external respiration
The pulmonary artery carries deoxygenated blood into the lungs from the heart, where it branches and eventually becomes the capillary network composed of pulmonary capillaries. These pulmonary capillaries create the respiratory membrane with the alveoli (Figure). As the blood is pumped through this capillary network, gas exchange occurs. Although a small amount of the oxygen is able to dissolve directly into plasma from the alveoli, most of the oxygen is picked up by erythrocytes (red blood cells) and binds to a protein called hemoglobin, a process described later in this chapter. Oxygenated hemoglobin is red, causing the overall appearance of bright red oxygenated blood, which returns to the heart through the pulmonary veins.
Compare and Contrast the functions of the upper respiratory tract with the lower respiratory tract
Upper: -structures are found in the head and neck and consist of the nose, pharynx, and larynx. Lower: -structures are located in the thorax or chest and include the trachea, bronchi, and lungs (= bronchioles, alveolar ducts, and alveoli).
Describe the mechanisms that drive gas exchange
Ventilation and Perfusion. Ventilation: is the movement of air into and out of the lungs. Perfusion: is the flow of blood in the pulmonary capillaries.
create a timeline of the phases of respiratory development in the fetus
Week 4-7: -Ectodermal tissue from the anterior head region invaginates posteriorly to form olfactory pits, which fuse with endodermal tissue of the developing pharynx. Week 7-16: Bronchial buds continue to branch as development progresses until all of the segmental bronchi have been formed. Beginning around week 13, the lumens of the bronchi begin to expand in diameter. By week 16, respiratory bronchioles form. The fetus now has all major lung structures involved in the airway. Week 16-24: -the development of the blood vessels, as well as the formation of alveolar ducts and alveolar precursors. At about week 19, the respiratory bronchioles have formed. In addition, cells lining the respiratory structures begin to differentiate to form type I and type II pneumocytes. Once type II cells have differentiated, they begin to secrete small amounts of pulmonary surfactant. Around week 20, fetal breathing movements may begin. Week 24-Term: -More alveolar precursors develop, and larger amounts of pulmonary surfactant are produced.At this point, pulmonary capillaries have formed and continue to expand, creating a large surface area for gas exchange. The major milestone of respiratory development occurs at around week 28, when sufficient alveolar precursors have matured so that a baby born prematurely at this time can usually breathe on its own. However, alveoli continue to develop and mature into childhood.
Compare and contrast fetal and adult hemoglobin
the partial pressure of oxygen is lower in the maternal blood in the placenta, at about 35 to 50 mm Hg, than it is in maternal arterial blood. The difference in partial pressures between maternal and fetal blood is not large, as the partial pressure of oxygen in fetal blood at the placenta is about 20 mm Hg. Therefore, there is not as much diffusion of oxygen into the fetal blood supply. The fetus' hemoglobin overcomes this problem by having a greater affinity for oxygen than maternal hemoglobin (Figure). Both fetal and adult hemoglobin have four subunits, but two of the subunits of fetal hemoglobin have a different structure that causes fetal hemoglobin to have a greater affinity for oxygen than does adult hemoglobin.
