Vertebrate Respiration Functions Gas Exchange we animals require oxygen and get rid of Carbon dioxide when too much of it makes the blood acidic, when lowering the ph of the blood it will interfere with a lot of the processes/systems in the body Body needs oxygen for metabolism, Final electron acceptor in the Electron Transport Chain Shifting of electrons allows for release of ATP Aerobic cellular respiration, anaerobic if you don t have oxygen terminates glycolysis end product is lactatic acid Carbon Monoxide preferred by hemoglobin will choose this over oxygen, common form of suicide via burning coal or car fumes What role does pyruvate play in anaerobic metabolism? Passive diffusion: simplest form May be due to diff. in pressure Gas goes to an area where there is less pressure (negative pressure) vaccum has to be filled up, principle by which we breathe in air, has to be a creation of negative pressure Dependent on surface area and difference in partial pressure Lower pressure creates a vacum which has to be filled up When organism gets too large cannot get completely dependent on diffusion Passive diffusion in the alveoli But we don t breathe in the skin If large organism means the volume is also very large, larger than surface area For every linear increase in dimension V=^3 Rely on diff. respiratory surfaces gills alveoli or lungs essentially filled with alveoli Ventilation flow of respiratory medium over respiratory surface Medium the one that carries the gas, respiratory surface one that gets the gas Medium water, respiratory surface gills When ventilating something running air over it When fishes ventilate their eggs they flap their fins over their eggs so that egss will not be coated with fungi Perfusion - Flow of blood through respiratory surface, driving of blood through capillaries, (aquatic: capillaries of gills, terrestrial: capillaries of lungs) Both are involved in unloading and loading gases There is gas exchange bet. the air and blood, and water and blood, Intimately connected with each other it depends on the habitat, ventilation and perfusion rates differ. how quickly the blood flows. how quickly the water flows
Water is a diff. habitat from air, in terms of oxygen, more oxygen in air, easier to extract oxygen in air Given that there is not much oxygen in water and diff. to extract oxygen from water, Ventilation supplies oxygen, small amount of water small amount of oxygen, slow flow of water but big flow of flood blood wasted cause it can t get oxygen Unidirectional vs bidirectional Bidirectional bec. it goes back humans (it goes back) Alveoli any of the many tiny air sacs in the lungs where the exchange of oxygen and carbon dioxide takes place are blind and dead closed on one end Air will come in through nares nostrils, have to go back air When new air comes in old air comes out theres mixing Basic Origins of the Organs Gills: from pharyngeal slits Lungs: endodermal outpocketings from the gut not homologous structures, endodermal Gas bladders: may be homologous to lungs Lungless animals that is homologous swim bladder maybe homologous to lungs, also come from the gut and serve the same function Ventilatory Mechanisms Ciliatory Mechanism same as passive type of diffusion, cilia drive water or air through epithelial lining so that gas will diffuse, we cannot completely rely due to surface area volume relationship, organisms get too large surface area not large enough Muscular mechanisms Dual pump (water ventilation) in most fishes, two phases involved, suction and force phase, depends on two pumps, two cavities, operculum bony covering of gills, continuous no gaps bet. stages Stage 1 both cavities buccal and opercular cavity expand, when they expand, water will spontaneously come in, increase in volume is accompanied by decrease in pressure, water will spontaneously come in, how they eat, mouths are closed and when see prey they open their mouth then vacuum is created, operculum not open If both mouth or operculum is open at point where two cavities expand, no negative pressure Fish needs quick flow of water so that pressure coming from the water as driving through the gills will pump out oxygen bec. of the high speed and pressure of water
Water enter buccal cavity pass through the gills, gills pick up oxygen with water and load carbon dioxide with water Stage 2 buccal cavity compressing, mouth is closed, if open during this then water will just go back out through mouth, water is pumped through gill curtain Stage 3 pressure is already positive, opercular valve already opens, pumping or compressing of opercular cavity pumps out, when negative water goes in, positive water will go out Stage 4 is beginning of stage 1 Point of water entry is suction Pump out is force phase When both cavities expand that s suction phase, when both cavities compress water is pumped out force phase Buccal pump (air ventilation) When frogs dive in water amphibians can stay underwater for quite sometime, do not have gills do not have operculum, simply breathes through skin when under water relies on cutaneous respiration Buccal pump respiration in frogs Frogs dependent on throat or mouth area Two types Two stroke air breathing fishes and most amphibians diff. in no. of strokes Four stroke When buccal cavity expands, air comes in nostrils are open there s something open, opening to windpipe trachea, to throat, both nostrils and external nares and glottis are open when mouth expands air enters from the outside through the nares into the mouth, old air from the lungs comes into the mouth via the glottis, expiration buccal cavity compresses Compression air goes out two ways Implies that there is mixing of new and old air Twice as fast but mixing Four stroke (in some salamaders)each compression phase is split into two, first stage of inspiration buccal cavity expands, only one arrow stage 1 only nares is open glottis is closed, during expansion, air enters through nares Stage 2 is compression buccal cavity compresses, glottis is open, nares closed, through the open glottis, even though compression still part of inspiration
Expiration starts, air goes into the mouth from the lungs, buccal cavity compresses, nostrils open, glottis closed, minimal mixing, a bit of mixing, surface of trachea Mixing is bad because you re breathing air that s not pure may be carbon dioxide Aspiration pump amniotes, medicine dropper aspirator valve, very dependent on particular muscles and creation of negative pressure Chest cavity Pl pleural cavity surrounding the lungs P pressure major blood vessel Superior Vena Cava drain upper parts of the body, large vein carrying deoxygenated blood into heart, carrying blood from the head, arms and upper body Jugular vein, brachial veins of arm Inferior Vena Cava drain lower parts of the body, carrying blood from lower body Femoral vein - bring blood back to the heart Right atrium where blood enters blood always receives blood via the atrium not ventricle, atrium receives blood form the outside Right deoxygenated blood, left always receives oxygenation Inspiration Inhalation Expiration exhalation Right Atrium During inspiration lungs expand, diaphragm contracts goes down, rib cage expands, increase volume of chest cavity, rib goes forward, increasing volume of pleural cavity, decreasing the pressure and also in the right atrium (expands) because it expands bec. of the negative pressure, vein will pump blood into the right atrium When chest cavity compresses, pressure is already postive, Right atrium compresses also, blood flows out of RA into RV Creation of negative pressure by increasing volume Compression of parts causes air to go back out bec. of positive pressure Phylogeny Sharks most primitive gnathostomes Elasmobranchii Countercurrent flow across the gills, flow of blood and water are in opposite directions, when in same direction (concurrent flow) why important in fishe water flows the opposite way, more efficient exchange of gases, concurrent flow same direction gas exchange will happen only
in point of contact, flowing in the same direction, countercurrent flow blood is flowing gas exchange happens in all point contact Fishes face the problem of not having enough oxygen One modification to allow them to extract oxygen more efficiently: high rate of water high pressure water coming in, higher ratio of ventilation to perfusion ratio Rate of ventilation is higher than perfusion Some sharks undergo Ram ventilation forward thrusting motion (obligate in some)have to moving fast very quickly so that water is forced into mouth then gills Required that they have to be swimming like that all the time if they stop they don t get oxygen Eyes do not close but they sleep Fish keeps moving while asleep, only half of the brain is asleep, moving forward but still sleeping First 2 mandibular arch and hyoid arch In sharks first gill slit reduced as a spiracle reduced gill slit, slightly for Chemoreception detecting chemicals in the water Shark pic Flow of water through the mouth of shark, unidirectional flow, animals do not have operculum, same principle as dual pump no opercular flap covering the gills, what happens is flow of blood, they share similar functions and structures, in heart (typical fish) pump blood in an aorta - major artery bring blood away from the heart artery away veins back,ventral aorta and dorsal aorta, heart pumps deoxygenated blood through the ventral aorta Heart of fish is very basic two main chambers main vein and atrium ventricle connected to ventricle is Major artery aorta Ventral aorta carries deoxygenated blood, major diff. bet heart of fishes and tetrapods, no point the heart will contain oxygenated blood. heart is supplied with own supply, always deoxygenated, when it came back from general circulation it was depriveed from oxygen, flows out through ventral aorta Branching off from ventral aorta, going toward the gills for oxygenation to get oxygen from gills, oxygenated blood will be leaving gills, goes into another set of arteries and into dorsal aorta carries oxygenated blood from gills to body, when it already supplied oxygenated blood to tissues individual veins will come back to heart to carry One is carrying oxygenated One is carrying deoxygenated blood One artery is blue the other one is red When blood vessel is red it is oxygenated, blue is deoxygenated Blue which is deoxygenated afferent Red are efferent Flow of blood through shark
Counter-current flow happens only in Ventral Aorta, functions only in oxygen extraction Osteichthyes bony fishes Operculum covers the gills Efferent artery oxygen from gills to dorsal aorta Some use gas bladders (sometimes connected to the buccal cavity via the pneumatic duct) Gas bladder connected via pneumatic duct Most fishes borrow oxygen from muscles Gas bladder (swim bladder) are homologous to lungs, internal gas-filled organ that contributes to the ability of a fish to control its buoyancy Lung fish doesn t have swim bladder anymore Amphibians Gill ventilation as juveniles Cutaneous respiration and lung ventilation as adults When under the water cutaneous respiration bec. lungs collapse too much pressure Reptiles Scales provide barrier in gas exchange, rely on aspiration mechanisms Single central air chamber with faveoli (compartments increase surface area and are sites of gas exchange) Repeated folds of the lungs, to increase surface area but not volume Sites of gas exchange also serve function of alveoli Aspiration (exhalation sometimes passive) In humans it is ussually passive Inhalation active bec. internal intercostals pull the ribs Muscles simply relax not active process Snake lungs are singular and divided into respiratory and saccular portions Modification for wider cavity allows them to eat larger Respiratory portion is the only one that is vascular supplied with blood vessels only part of the single large responsible for gas exchange acts as the diaphragm important in causing the creation of negative pressure, spreads out the respiratory portion of singular lung thus increasing its volume Saccular non-vascular no gas exchange simply for compression and increasing the volume of the lung Crocodiles liver moves toward the tail increases the chest cavity, when liver goes back forward, livers of crocodile are moving Limb movements, when withdraw limbs into shells, compress chest cavity, spread legs-expand chest cavity Turtles limited amount of cutaneous respiration in some parts o their body particularly around their anal region in some turtles and lizards Unidirectinal airflow Non fishes its bidirectional but in alligators its unidirectional flow
Birds Address diff. problems because they fly Passageways branch off into parabronchi (unidirectional) Flow of air will be unidirectional, their air sacs are not blind and dead and they re in series, parabronchi will be respiratory surfaces for gas exchange, each of this will get oxygen, has to be efficient, fly up where atmosphere is much thinner With 6-12 (usually nine) avascular (no blood vessels no gas exchange) air sacs, which extend into the cores of large bones, these air sacs are for the complete separation bet. oxygenated and deox air Organisms face always the issue of mixing, birds cannot afford that bec. they need fresh air all the time, they have to be much more effifient at extracting oxygen from the air Trachea lungs Anterior air sacs and posterior Particle cycle of breathing, takes two inspiration rounds and expiration rounds Inspiration 1 Bird opens its nostrils air comes in goes to trachea after entering the glottis,air that trachea takes in not all goes to the lungs, the rest goes to the posterior air sacs Air in the posterior air sacs avascular, air that goes into the lungs there will be gas exchange, inspiration 1 Expiration 1 Air in the lungs goes out, air coming from the lungs, air in the posterior air sacs now goes into the lungs, lungs can get oxygen from them, outward direction, doesn t flow outward the trachea Inhalation 2 Bird breathes in again, air comes in, new air, this goes to the same, goes into the lungs and the posterior air sacs, problem here is there is cold air in the lungs at that point from posterior airs sacs, there will be mixing, it will go to the anterior air sacs Expiration 2 Everything goes out, new air, old air in lungs and old air in anterior air sacs all go out, very efficient, one rule of thumb, anterior airsacs will contain old air Posterior airsacs new air Anterior always to separate old air Lungs of birds more active act as pump A bit more force required Continuous process I1 New air goes into the lungs and the posterior airsacs
E1 Old air goes out new air from posterior airsacs bone to the lungs I2 Have to segregate so it goes to anterior airsacs Air never goes directly from posterior to anterior posterior always carrying new air Anterior always carrying old air E2 new air goes to lungs then go out Crosscurrent flow at an angle,flow of air have series of tubes parabronchi Series of respiratory that are perpendicular, very efficient, gas exchange at a point of contact Mammals Extensive use of diaghpragm (muscle when contracts it shortens it goes down it will increase chest cavity volume causing inhalation) and intercostals External intercostals pull the ribs outward and upward Internal intercostals Downward and backward With alveoli (bidirectional) Viscera also assist in respiration Not reliant Just accesory Functional considerations Types of flow Ventilation and perfusion rates should be balanced (ratios depend on ecology) 1:1 terrestrial Fishes can go as high as 30:1, needed by fishes Can go if you breathe in actively more increasing ventilation rate, not very efficient, just wasting amount of air taking in, wasting when blood is flowing the same rate Metabolic costs of living in water because denser and less oxygen more diff. to extract vs air Regulation of blood ph levels When have a lot of carbon dioxide increase the acidity of the blood need to get enough oxygen when not getting enough oxygen muscular activity will rely on lactic acid metabolism part of reason why you get cramps, oxygen debt lactic acid build up only when not enough oxygen,really need to get better supply of oxygen, natural tendency of body when tired breathe in more