BIOL 112 1st Edition Lecture 19 Outline of Last Lecture I. Shift at BirthII. Pathologies/DefectsIII. BloodOutline of Current LectureIV. Measurement of Blood VolumeV. Gas ExchangeVI. Respiratory SystemVII. Breathing (Ventilation)Current LectureI. Measurement of Blood Volume•Too crude to cut a major vessel to drain all the blood and measure it, obviously.•General approach — dilution method•Inject measured amount of labeled substance into blood, allow substance to mix in blood, and withdraw a sample and measure the extent to which the substance has been diluted.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.•Plasma Volume: Use a soluble dye - dye must be inert and cannot pass through cell membranes (Evans Blue is usually used)•Hematocrit - the proportion of volume of whole blood occupied by cells (mostly erythrocytes), usually around 40%.•If hematocrit is 40% of volume, then plasma occupies 60% of vol-ume.II. Gas Exchange•Aerobic cells need Oxygen and release CarbonDioxide, which are exchanged with the environ-ment (source of gasses - atmosphere)•Barometer - invented by Evangelista Torricelli(1643)•measures atmospheric pressure, the “weight” of air pressing down on mercury (Hg) pushes itup the tube to fill the vacuum. Gas pressure canbe expressed as the height of Hg in a column.•Not necessary to use mercury, the earlierbarometer by Torricelli used water, but water isless dense.•Partial Pressure•1 atmosphere pressure = 760 mm Hg•Can parse the contributions of each gas to the total air pressure: partial pressure. It is a more biologically significant expression of available gas concentration for gas exchange.•Humans at High Altitude•Humans at 15,000 ft or higher show mental and physical impair-ment within an hour or less from hypoxia•Solutions to problem?•Breathe pure oxygen: the upper limit is 40,000 ft. Above that limit, even pure oxygen can’t support life.•Pressurize cabin•Comparative Gas Exchange•Cells need to be < 1 mm from environment for adequate gas ex-change•Sample organisms: protozoa, primitive metazoa•Bigger organisms, especially lang organisms, need specialized exchange structures•Fish and other aquatic organisms: gills•Insects: tracheae and spiracles•Terrestrial organisms: lungsIII. Respiratory System•Structures of the Respiratory System•Nasal passages, Pharynx (with epiglottis), Larynx (with vocal cords), Trachea, Bronchi, Bronchioles, Alveoli, Ribs, Intercostal Muscles, Diaphragm•Functions of Respiratory System:•Breathing - obviously. lungs and stuff.•Air Processing - preparing the air for use by alveoli•Vocalization•Gas ExchangeIV. Breathing (Ventilation)•In mammals, air is pulled into lungs•Inhale:•diaphragm contracts (pulls down) and intercostal muscle contrac-tion (lifts rib cage)•Both actions increase volume of chest cavity, creating a partial vacuum•Air rushes into lungs to relieve vacuum•Exhale:•In Simple Exhalation: relaxed muscles, diaphragm returns to arch shape, intercostals allow rib cage to rotate down, gently pushes air out of lungs•In Forcible Exhalation: accomplished by contraction of a different set of intercostal muscles (forces rib cage down), abdominal mus-cles contract, force organs upward & diaphragm up, reduce vol-ume of chest cavity and force air out of lungs•Alveolar Ventilation•Tidal volume = 500 ml•Not all lung volume is alveoli - in bronchi and bronchioles, there is no gas exchange•Dead volume = 150 ml (lungs are never completely empty)•So alveolar volume = 500 - 150 = 350 ml with each tidal breath•Alveolar Ventilation = respiratory rate X alveolar volume = 12/min X 350 ml = 4,200 ml/min moved in and out of alveoli•21% of this is oxygen, so 880 ml oxygen in lungs/min•Human at rest consumes ~200 ml 02 in lungs/min•Extra supply of oxygen becomes available for activities without in-creasing volume or rate of