BIOL 320 1st EditionLecture 16Outline of Last Lecture I. Respiratory ZoneII. Respiratory MembraneIII. LungsIV. Pleural CavityV. BreathingVI. Pressure RelationshipsVII. Forces Acting on LungsVIII. Boyle’s LawIX. InspirationX. ExpirationXI. Resistance to AirflowXII. Lung ComplianceXIII. Gas ExchangeXIV. Oxygen TransportXV. Carbon Dioxide TransportOutline of Current Lecture XVI. Oxygen/Carbon Dioxide ExchangeXVII. Oxygen-Hemoglobin Dissociation CurveXVIII. Factors Influencing Hemoglobin SaturationXIX. Neural ControlXX. Depth and Rate of BreathingXXI. HyperventilationXXII. HypoventilationXXIII. Gas ImbalanceXXIV. Developmental AspectsI. Digestive SystemII. Digestive ProcessIII. Regulation of DigestionIV. PeritoneumV. Histology of the GI TractVI. Oral CavityVII. TongueCurrent LectureOxygen/Carbon Dioxide ExchangeOxygen-Hemoglobin Dissociation CurveFactors Influencing Hemoglobin SaturationNeural Control- Dorsal Respiratory Group: near base of nerve IX; located in the medulla oblongata; integrate central & peripheral chemoreceptor input to VRG --> *modify rhythm*- Ventral Respiratory Groupo -Location: medulla oblongatao -Two groups of neurons: inhale & exhaleo -Function: rhythm-generating & integrating centero -Sets: eupnia (regular breathing rate…12-15 breaths/min)- Pontine Respiratory Centerso -Overall functions: influence & modify activity of medullary centers (smoothing out transitions between expirations and inspirations)- Rhythm Theories:1. Inspiratory neurons = pacemakers2. Reciprocal inhibition of interconnected medullary networks --> 2 sets of pacemakers (most agreed on)3. 3.Stretch receptors in lungs establish rhythmDepth and Rate of BreathingHyperventilation- -Benefit: clear CO2 from system- -Hypercapnia: increased [CO2] in blood; triggers increased ventilation- -Voluntary hyperventilation: no real increase in [O2] in blood but removes [CO2]o Dangerous if overdone => triggers respiratory alkalosis (dizziness)Hypoventilation- -Characteristic: slow, shallow breathing due to low [CO2] in blood- -Apnea: cessation of breathing; restarts when [CO2] levels high enough to trigger respiration --> happensto some when sleepingGas Imbalance- The Bendso -Mechanism: N2 insoluble at atmospheric pressure; if return to surface to fast the solubilized N2comes out of solution quicklyo -Symptoms: dizzy; being on fireo -Treatment: decompression chamber- Carbon Monoxideo -Mechanism: CO has greater affinity to Hb than O2; if CO binds to Hb, then it displaces O2 binding --> hypoxia --> pass outo -Treatment: hyperbaric O2 chamber- Oxygen Toxicityo -Mechanism: O2 is a free radical at high pressures --> destroy tissues (particularly highly vascularized tissues)Developmental Aspects- Fetuso Autonomous respiration @ 28 weeko Lungs filled with fluido Site of gas exchange is the placenta- At Birtho Respiratory center activatedo Respiratory rate = highest ever in lifetime- Childhood Development- Respiratory efficiency decrease with old ageDigestive System- -Components: alimentary canal (GI tract) & accessory organs- -GI Tract Function: digest and absorb food/nutrients- -GI Tract Organs:1. Mouth2. Pharynx3. Esophagus4. Stomach5. Small intestine6. Large intestine- -Accessory Organs:1. Teeth2. Tongue3. Salivary glands4. Gallbladder5. Liver6. PancreasDigestive ProcessRegulation of Digestion- -Mechanical & Chemical Stimuli- -Intrinsic Control: short reflex- -Extrinsic Control: long reflex…use same system but also involves the brain- -Local Enteric Nerve Plexi: used by both reflexes to effect smooth muscles/glands…the 'gut brain'Peritoneum- -Visceral peritoneum: located on/lines the organ- -Parietal peritoneum: lines the body cavity- -Peritoneal cavity: located between & has serous fluid- -Mesentery: double layer of peritoneum that extends from body wall to organ- Functions:1. Attaches2. Contains blood vessels, lymphatics, and nerves3. Stores fat- -Retroperitoneal organs: found outside the parietal peritoneum against dorsal body wallHistology of the GI TractOral Cavity- Boundaries: lips, plate, cheeks, tongue- Anterior opening: mouth- Posterior opening: oropharynx- To withstand abrasion:o -Epithelial lining: SS epitheliumo -Keratinized: gums, hard palate, dorsum of tongue- Lips and Cheeks:o -Skeletal muscles: lips (orbicularis oris) & cheeks (buccinators)o -Oral cavity proper:o -Labial frenulum:- Palate:o -Hard Bones: maxilla, palatine Function: assists tongue in chewingo -Sof Main component: skeletal muscle Uvula: extension --> closes nasopharynx when swallowTongue- -Location: ⅔ mouth; ⅓ orophayrnx- -Functions:1. mix food with saliva2. Grip/position food3. Initiates swallow- -Papillae: grippers; location of taste buds- -Intrinsic muscles: movement in - -Extrinsic muscles: protrusion of tongue- -Lingual frenulum: string that holds tongue in