Vertebrate Physiology PCB 3743 Exam 4 Study GuideAnatomyYou should know (i.e. be able to label) the following organs: The basic anatomy of the lungs and alveoli (Figure 16.4 and 16.14). The villus in the small intestine (Fig 18.10). The hepatic portal vein, gallbladder, and bile duct (Fig 18.23). The pancreas (Fig 18.25 & 18.27). The kidney and a nephron (Fig 17.1, 17.2, 17.5, 17.8).Basic anatomy of lungs and alveoli (Figure 16.4 and 16.14)Villus in small intestine (18.10)The hepatic portal vein, gallbladder, and bile duct (Fig 18.23)The pancreas (Fig 18.25 & 18.27)The kidney and a nephron (Fig 17.1, 17.2, 17.5, 17.8)Chapter 16 Respiration1. Know the basic anatomy of the lungs, alveoli, and pulmonary circulation. Understand the different intrapulmonary and intrapleural pressures. Understand physical properties of the lungs,and the role of surfactant and surface tension within the alveoli. Know the mechanics of breathing (Figure 16.14)a. Anatomyi. Glottis – space between vocal folds which vibrate to create soundii. Larynx (voice box)– holds vocal folds and is attached to tracheaiii. Trachea – tube connecting pharynx to lungs and allows breathingiv. right & left bronchus – trachea splits into two bronchi which attach each lungv. bronchiole – branches from bronchi into lungs allow air to reach alveolivi. alveolar sac – bunch of alveoli together in a sac that connect to bronchioles vii. alveoli – each alveolus is a circular ball that increases lung surface area for gas exchangeviii. Type 1 alveolar cell – make up structure of all almost all alveolar wallsix. Type 2 alveolar cell – less common, secrete the pulmonary surfactantx. diaphragm - divides thoracic cavity from abdominopelvic spaceb. Intrapulmonary/Intrapleurali. Intrapulmonary - inside the lungs1. At rest, intrapulmonary pressure = atmospheric pressureii. Intrapleural - space between the lungs and the chest wall.1. Intrapleural pressure less than atmospheric pressure, so lungs kept inflated against chest walliii. Boyle’s Law – pressure drops as volume increases1. => lowering diaphragm = increase in lung volume = decrease intrapulmonary pressure = suck air into lungs2. Raising diaphragm = increase intrapulmonary pressure = force air outc. Physical properties of lungsi. Compliance - amount lung inflates with a pressure changeii. Elasticity - amount that lung resists inflation and recoils back to resting state (lungs stuck to chest wall, so always in elastic tension)iii. Surface Tension - film of fluid on inside of alveoli has surface tension (attraction of water molecules), tending to collapse the alveoliiv. Surfactant1. phospholipid-protein detergent that breaks surface tension2. made by Type 2 alveolar cellv. Disorders of surface tension1. cystic fibrosis - genetic defect causes lack of fluid secretion, so airway fluid is very viscous2. acute respiratory distress syndrome (ARDS) - inflammation in lungs leads to excessive accumulation of fluid & reduced surfactant release3. premature infant - surfactant not produced until late in gestation (just before birth), so premature infants have collapsed alveoli unless surfactant is administered(16.14)2. Understand the partial pressure of gases in the atmosphere and blood. Understand the different partial pressures of O2 and CO2 at different points of the circulation. Understand the regulation of breathing, and the control of breathing by CO2 and pH of the blood and CSF.a. Lung Volume/Capacityi. Total Lung Capacity - gas in lungs after maximum expansionii. Tidal Volume - gas breathed in and out at restiii. Vital Capacity - gas breathed in and out at maximum inspirationiv. Residual Volume - gas left in lungs after maximum expirationb. Partial pressure = fraction of total pressure exerted by particular gasi. Example1. atmospheric pressure is 760 mmHg 2. O2 is 20% of atmosphere3. PO2 = 0.20 x 760 = 152 mmHgii. O2 diffuses from higher PO2 to lower PO2iii. Because O2 is leaving lungs into blood, and CO2 is entering lungs from blood, PO2 is lower in lungs than in atmosphere, and PCO2 is higher in lungs than in blood.iv. Gas concentration in blood is also measured in partial pressure = pressure required to dissolve that much of the gas in the blood.v. P O2 is high in blood leaving lungs, PO2 low in blood leaving tissue.vi. P CO2 is low in blood leaving lungs, PCO2 is high in blood leaving tissue.c. Control of Breathingi. Holding breath (hypoventilation) allows build up of CO2.ii. Faster breathing (hyperventilation) blows off more CO2 (lowers PCO2 in blood)iii. Restful Breathing - Rythmicity area in brainstem set ups rhythm iv. Periodic inhalation caused by rhythmic firing of I motor neurons -> lowering of diaphragm -> inspirationv. Inhalation is terminated by feedback from lung stretch sensors that inhibit inhalation (I) motor neurons, and excite exhalation (E) motor neurons = expiration.vi. Modulation - rhythmic breathing modulated by:1. 2 centers in pons: pneumotaxic (inhibits I) & apneustic (stimulates I) 2. Rhythmicity area in medulla3. Voluntary control from cortex4. Chemoreceptors in aorta, carotid body, and brainstem.vii. If PCO2 gets too high, CO2 -> HCO3- -> lower pH (more acidic).viii. Drop in pH in brain make respiratory control centers speed up breathingd. CO2 and Bicarbonate act as a pH Buffer in the bloodi. CO2 +H20 ↔ carbonic acid ↔ bicarbonate + H+1. Takes place in CEREBRAL SPINAL FLUID (CSF)ii. If blood pH is too high (basic) breathe less to retain CO2:1. more CO2 -> more bicarbonate + more H+ = more acidiii. If blood pH is too low (acidic) breathe more to blow off CO2:1. less CO2 -> less bicarbonate + less H+ = less acide. Examplesi. Rebreathing air(paper bag): CO2 drops as O2 drops = breathing rate increasesii. Rebreathing air with CO2 filter: O2 drops but CO2 stays low. Breathing rate does not increase, brain runs out of oxygeniii. CO2 levels control breathing:1. Increasing CO2 causes bigger change in breathing than lowering O23. Understand the nature of hemoglobin, and the loading and unloading of O2 from the hemoglobin.a. Hemoglobin - respiratory pigment picks up oxygen from lungs, releases oxygen into tissues increasing oxygen carrying capacity of blood (oxygen dissociates from hemoglobin in low pH environment)i. Consists of 4 protein subunits (2 x alpha, 2 x beta subunits) and 4 heme molecules (centered around iron atom that binds O2 molecule). Iron gives bloodreddish hue.ii. Oxyhemoglobin- when carrying oxygeniii. Deoxyhemoglobin -
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