BIO 241 1st Edition Lecture 15Outline of Last Lecture I. Lungs 1II. Lungs 2III. Alveolar-capillary membraneIV. Physiology of respirationV. InspirationVI. ExpirationOutline of Current Lecture II. ComplianceIII. Pulmonary a. Volumesb. Capacitiesc. RatesIV. Diffusion of oxygen and carbon dioxideV. Dalton’s LawVI. Partial pressures of oxygenVII. Partial pressures of carbon dioxideVIII. External (pulmonary) respirationIX. Internal (tissue) respirationX. Oxygen transport 1Current LectureII. Compliance is the ease with which the lungs and thoracic wall can be expanded during inspiration. A higher compliance means easier breathing. Compliance is related to two factors: elasticity and surface tension. Compliance decreases with any condition that destroys lung tissue (emphysema), fills lungs with fluid (pneumonia), produces surfactant deficiency (premature birth, near-drowning), and interferes with lung expansion (pneumothorax).III. a) There are several respiratory volumes that you need to know. The first is tidal volume (TV) the lung volume representing the normal volume of air displaced between normal inhalation and exhalation when extra effort is not applied. This has a volume of 500 mL. Three different volumes contribute to this tidal volume. The first is anatomical dead space which holds about 150 mL (air in nose, mouth, bronchi, all the conducting organs). The second is alveolar ventilation which holds 350 mL (how much air actually made it to the alveoli). The third isphysiological dead space which holds 0 mL (portions that receive no air such as portions that are bronchoconstricted). You also need to know the inspiratory reserve volume (IRV) which is 3000 mL (the additional air that can be forcibly inhaled after the inspiration of a normal tidal volume), expiratory reserve volume (ERV) which is 1200 mL (the additional air that can be forcibly exhaled after the expiration of a normal tidal volume), and the residual volume (RV) (the volume of air still remaining in the lungs after the expiratory reserve volume is exhaled). Residual volume is important so that alveoli do not close and so that gas exchange is always occurring. b) There are also some equations you need to know relating to lung capacity and volumes. Total lung capacity is found by TV + IRV + ERV + RV. Vital capacity is the maximum amount of air a person can expel from the lungs after a maximum inhalation and is around 4700 mL. It is found by TV + IRV + ERV. Inspiratory capacity is the total amount of air that can be drawn into the lungs after normal expiration. It is found by TV + IRV. Functional residual capacity is the volume of air present in the lungs at the end of passive expiration. It is found by RV + ERV.c) There are two rates you need to know involving respiration. The first is maximum voluntary ventilation which is the maximum amount of air that can be inhaled and exhaled within one minute. It is found by TV x breaths/min. Alveolar ventilation rate is the volume of gas expired from the alveoli to the outside of the body per minute and is found by AV x breaths/min.IV. Oxygen always flows down its concentration gradient. In the body, this goes from alveoli → blood → interstitial fluid → body cells. Body cells are constantly using oxygen. This will only go to equilibrium when dead. Carbon dioxide will always flow down the concentration gradient as well. However, its higher pressure is located in the body cells; therefore, it flows from body cell → interstitial fluid → blood → alveoli. V. Dalton’s Law states that, each gas in a mix of gases, exerts its own pressure as if there were not other gases. Therefore, each gas has its own partial pressure (P).VI. The partial pressures of oxygen are shown below in order:alveolar air = 104 mmHg External respirationdeoxygenated blood = 40 mmHg External respirationoxygenated blood = 104 mmHg Internal respirationinterstitial fluid = 40 mmHg Internal respirationcytoplasm = <40 mmHg Internal respirationVII. alveolar air = 40 mmHg External respirationdeoxygenated blood = 46 mmHg External respirationoxygenated blood = 40 mmHg Internal respirationinterstitial fluid = 46 mmHg Internal respirationcytoplasm = >46 mmHg Internal respirationVIII. External (pulmonary) respiration is between alveoli and pulmonary blood. With this, blood gains oxygen and loses carbon dioxide. This diffusion occurs 100% of the time. The diffusion rateis dependent on the partial pressures of oxygen and carbon dioxide (Henry’s Law), total surface area of the lungs (Fick’s Law), diffusion distance (Fick’s Law), breathing rate and depth, and ventilation-perfusion coupling (not that important). One important thing to note is that carbon dioxide and oxygen diffusion rates are completely independent. IX. Internal (tissue) respiration is between blood and tissue cells. Blood loses oxygen (25% is given up at rest) and gains carbon dioxide. Diffusion will also occur 100% of the time. X. 98.5% of oxygen is transported as oxyhemoglobin. If you recall, 1 molecule of hemoglobin cancarry 4 oxygen molecules. If a hemoglobin is fully saturated, then it is carrying 4 oxygen molecules. If it is 50% saturated, it is carrying 2 oxygen molecules. This is known as partial saturation. The oxyhemoglobin-dissociation curve states that less oxygen is released to tissues during exercise than if one were at rest. The partial pressure of oxygen is the most important factor is oxygen