Presentation on theme: "Chapter 21 Control of Respiratory Function"— Presentation transcript:
1 Chapter 21 Control of Respiratory Function Essentials of PathophysiologyChapter 21 Control of Respiratory Function
2 Pre lecture quizFPulmonary ventilation is the movement of blood through the lungs.Deoxygenated blood leaves the right heart through the pulmonary veins.The peripheral chemoreceptors monitor arterial oxygen levels and will stimulate respirations when the PO2 has dropped below 60 mm Hg.Lung compliance refers to the ease with which the lungs can be inflated.The effects of airway resistance on airflow can be illustrated by using Poiseuille’s law, which states that resistance to flow is inversely related to the fourth power of the radius.FTTT
3 Pre lecture quiz Diffusion dissociation peripherial Surfactant Vasoconstriction__________ exerts very important effects on lung inflation, including lowering the surface tension, increasing lung compliance and ease of inflation, and assisting in preventing pulmonary edema by keeping the alveoli dry.The relation between the oxygen carried in combination with hemoglobin and the PO2 of the blood can be described using the oxygen–hemoglobin __________ curve.The most important chemoreceptors for sensing changes in blood carbon dioxide content are the __________ chemoreceptors.__________ refers to the movement of gases in the alveoli and across the alveolar–capillary membrane.The blood vessels in the pulmonary circulation undergo marked ________________ when they are exposed to hypoxia.
4 Lung Functions Gas exchange Moves O2 into blood Removes CO2 from blood Blood storageRegulate vasoconstricting substancesBradykinin-Angiotensin IIHeparin-formed locally in injured tissue, acts in vasodilation of small arterioles, is considered to play a part in inflammatory processessulfuric acid ester that occurs especially in the liver and lungs, that prolongs the clotting time of blood by preventing the formation of fibrinobtained from the liver and lungs of domesticated food animalsprotamine sulfate- is a heparin antagonist
5 Conducting Airways Move air into lungs Warm and humidify air Trap inhaled particles (Mucus escalator)
6 Conducting & respiratory Airways Note Change of Cell Type & Thinning of Air to Blood DistanceAuthor: Please add title.
7 Membranes and Cavities Parietal pleuraVisceral pleuraPleural space (between pleurae)Mediastinum
8 Respiratory Airways Bronchioles Alveoli Gas is exchanged with the blood
10 AnswerParietal pleuraThe organs and walls of the thoracic and abdominal cavities are covered with serous membranes. Visceral membranes cover the organ; parietal membranes line the cavity walls. The two membranes and the space between them allow for ease of movement.The thoracic cavity is lined by parietal pleura; the lungs are covered by visceral pleura.
11 Respiratory Muscles Diaphragm Accessory muscles of inhalation External intercostalsScaleneSternocleidomastoidAccessory muscles of exhalationInternal intercostalsAbdominal muscles
12 QuestionTell whether the following statement is true or false: During inhalation, the diaphragm contracts and flattens.
13 AnswerTrue The diaphragm is the main muscle of inhalation/inspiration. During inhalation, the diaphragm contracts and flattens (it moves downward in order to accommodate the volume of air you are taking in, allowing space for the lungs to expand). During exhalation, the diaphragm relaxes and moves back up.
14 Compliance How easily lungs can be inflated depends on: Elastin and collagen fibersWater contentSurface tension
16 Scenario: Question: A man’s lungs were damaged during a fire He developed severe respiratory distressThe doctor said smoke inhalation had caused an inflammation of his alveoliThe damage had also destroyed some of his surfactantQuestion:What had happened to his lung compliance?Why was he given positive-pressure ventilation?
21 Forced vital capacity MMEF =Mean Mid Expiratory Flow Matching: Normal expirationObstructive expirationRestricted LungsA B CVolume diagramABCFlow diagram
22 QuestionWhich measure of lung function indicates the total amount of air that the lungs can hold?Tidal volumeFunctional residual capacityVital capacityTotal lung capacity
23 Answerd. Total lung capacity is the maximum amount of air that the lungs can hold—everything (volume-wise) at the end of a maximal inhalation (the deepest breath one can possibly take). Normal TLC is approximately 6 L.
24 Gas Exchange Oxygen moves from alveolar air into blood Carbon dioxide moves from blood into alveolar air
25 Ventilation and Perfusion Scenario:A child has inhaled a peanut, blocking her left primary bronchus.Question:How will the ventilation in her two lungs change?How will the composition of the air in her two lungs differ?Which lung should she send more blood to?How should her body alter perfusion of the lungs?
26 Ventilation–Perfusion Mismatching In mismatch Blood goes to parts of the lung that do not have oxygen, andBlood does not go to parts of the lung that have oxygenIn normal function blood perfusion is routed opposite of other body tissues.Blood with no airAir with no BloodAir and blood
27 QuestionTell whether the following statement is true or false: Ventilation-perfusion mismatch results in hypoxia.
28 AnswerTrue In either case (ventilation without perfusion or perfusion without ventilation) oxygen is not picked up by the capillaries and delivered to the tissues. The result of decreased oxygen at the tissue level is termed hypoxia.
29 Blood Gases—Oxygen Dissolved oxygen = PaO2 or PO2 Normal value >80 mm HgOxygen bound to hemoglobin = oxyhemoglobinNormal value 95% to 97% saturation
30 Hemoglobin Holds 4 Oxygen Molecules How saturated is this molecule of hemoglobin?How could a person have a hemoglobin saturation of 95%?Author: Add text?
31 Oxygen Capacity Amount of oxygen the blood can hold What is the oxygen capacity of normal blood?What is the oxygen capacity of anemic blood?mg/dLmg/dL
32 Oxygen ReleaseIf the blood released half of its oxygen to the tissues …How much oxygen would the normal tissues receive?How much would the anemic person's tissues receive?
33 Oxygen Release (cont.) Most body tissues have a PO2 of 40-60 mm Hg How much oxygen does the normal blood release at a PO2 of 40 mm Hg?The anemic blood?Author: Add text?
34 Factors that shift the curve: Oxygen AffinityHow tightly the hemoglobin holds onto the oxygenWhich of these hemoglobin samples has the highest oxygen affinity?Which will release the most oxygen to the tissues?ABCPO2Factors that shift the curve:CO2, pH, DPG, Fetal Hb
35 Blood Gases—Carbon Dioxide Dissolved carbon dioxide = PaCO2 or PCO2Normal value 35–45 mm HgCarbon dioxide bound to hemoglobin = carbaminohemoglobinCarbonic acid bicarbonate ion and H+When you exhale you remove CO2 from your blood and also decrease the amount of carbonic acid, raising your blood pHCO2 + H2O H2CO3 H+ + HCO3-
36 QuestionTell whether the following statement is true or false: The relationship between PCO2 and pH is direct.
37 AnswerFalseThe relationship is indirect. As PCO2 levels rise, the amount of carbonic acid in the blood increases, making the pH more acidic (decreasing it).CO2 + H2O H2CO3 H+ + HCO3-pH=𝑙𝑜𝑔 1 [ 𝐻 + ]
39 Chemoreceptors Can Adjust Respiration Rate Central chemoreceptorsMeasure PCO2 and pH in cerebrospinal fluidIncrease respiration when PCO2 increases or pH decreasesPeripheral chemoreceptorsMeasure PO2 in arterial bloodIncrease respiration when PO2 <60 mm Hg
40 ScenarioYou are caring for a COPD client…He has chronically high PCO2He is being given low-flow oxygen and complains all the time that he “needs more air,” so you turn up his oxygen.Question:When you check on him later, he is unconscious and not breathing. What happened?