Chapter 13Lecture 18, 30 Oct 2003Chapter 12, Circulation (con’t)Chapter 13, Respiration, Gas Exchange, Acid-Base BalanceVertebrate PhysiologyECOL 437University of ArizonaFall 2003instr: Kevin Boninet.a.: Bret Pasch1Vertebrate Physiology 4371. Circulation (CH12)2. Blood-Gas Chemistry (CH13)3. Announcements...214-34, Vander 2001See (12-32)Thursday, 30 October -- the ARLDN's 2003 Edmund A. ArbasLecturer, Prof. Peter M. Narins from the Dept. of Physiological Science atUCLA, will give his public lecture in Economics 110 at 4:00 pm. The titleof his lecture is "Science on Seven: Adventures of an ExpeditionaryBiologist."Narins is renowned for his elegant work on hearing and auditorycommunication in frogs and is a world leader in neuroethology, animalbehavior, and auditory neurophysiology. He is also a legendary fieldbiologist, having led 39 expeditions to remote and exotic field sites onseven continents over the last quarter century. A masterfully clear andvery entertaining speaker, he has won the most prestigious teachingawards atUCLA.2bName that student:3Drew StasiakChem MinorElena CostinMCBGabriel ReinhardtMCBHemodynamics in VesselsVander 200114-11, Vander 2001Flow depends primarily on pressure gradient and resistance4Hemodynamics- Poiseuille’s Law:Flow rate8Lη Q = (P1 – P2)πr4Pressure Gradientradius4lengthviscosityUse to approximate flowSmall change in radius Æ large change in flow rate5Hemodynamics- From Poiseuille’s Law:ResistanceQ R = (P1 – P2)Pressure Gradientradius4Flow rateviscositySmall change in radius Æ large change resistance= 8Lηπr4lengthModifiable if vessel distensible under pressure6(12-25)Summed resistancereduces pressure…7(12-23)Total Flow Rate same allalong Circulatory System8RiverLakeRiver(12-24)Shapes of curves slightly different because ofRBCs (viscosity) and fact that they tend to flowin middle of lumen9Peripheral Circulation- Endothelium lining vessels- Middle layer with smooth muscle (esp. arteries)- Outer fibrous layerCapillaries with ~ only Endothelium10(12-26)11Peripheral CirculationCompliance vs. Elasticity~ Veins vs. ArteriesVolume Reservoir vs. Pressure Reservoir12Volume Reservoir vs. Pressure Reservoir14-34, Vander 2001(12-27)~Constant P and Q at Capillaries!See (12-32)13Venous System- low pressure (11 mm Hg or less)- thin walled veins with less muscle- more compliant and less elastic- valves- blood moved by skeletal muscle (and smooth)- breathing creates vacuum (low pressure) inchest to aid blood flow to heart14Microcirculation- endothelium in capillaries is permeable1. continuous2. Fenestrated (kidney, gut)3. Sinusoidal (liver, bone)Less permeable- Movement across walls, between walls, in vesiclesMore permeable- Bulk Flow…15Bulk Flow…Fluid Pressurevs.Osmotic Pressure(12-38)Filtration > UptakeLymph System to return excess fluidFaster than diffusion16Bulk Flow…- Edema- No RBCs; therefore not redLymph System- Starvation- Lungs- Kidneys- Drains interstitial spaces- has valves and smooth musculature- empties into thoracic duct at vena cavae- transport system for large hormones and fats into blood stream- filariasis, elephantiasis- Reptiles and Amphibians with lymph hearts17Giraffe example pgs. 504-505Why does blood in the lowerextremities of aquatic organismsnot pool as it may do in legs ofhumans, giraffes, etc.?FISH:Blood tends to pool in tail b/c inertia andcompression waves when swimming-Veins in middle of body-Accessory caudal (tail) heart in some species18Circulatory System Regulation1. Feed Brain and Heart First2. Next Feed Tissues in Need3. Maintain volume, prevent edema, etc.BaroreceptorsChemoreceptorsMechanoreceptorsThermoreceptorsInfo. integrated at Medullary Cardiovascular Centermedulla oblongata and ponsDepressor Center Æ Parasympathetic EffectorsPressor Center Æ Sympathetic Effectors19Circulatory System RegulationBaroreceptors increase AP firing rate when BP increasesSensed at carotid sinus,aortic arch, subclavian,common carotid,pulmonaryUsually leads to Sympatheticsuppression to decrease BP(12-43)20Circulatory System RegulationArterial Chemoreceptors in carotid and aortic bodies(More details when discuss ventilation)e.g., low O2, high CO2, low pHleads to bradycardia and peripheral vasoconstriction(diving and not inflating lungs)21What about when not diving?Circulatory System RegulationCardiac Mechanoreceptors and ChemoreceptorsAlter heart rate AND blood volumee.g.,ANP (Atrial Natruiretic Peptide) released in response to stretch- leads to increased Na+ excretionand therefore greater urine output22Circulatory System RegulationExtrinsic vs. Local ControlNeuronal orHormonalMost arterioles with sympathetic innervationAlso respond to circulating catecholamines:-At high levels, alpha adrenoreceptors are stimulated Ævasoconstriction (to increase BP)-At low levels, beta2 adrenoreceptors are stimulated Ævasodilation (to increase flow to tissue)-Response depends on tissue type, receptor type(s), levelof catecholamines (epi, norepi), etc.23Circulatory System RegulationExtrinsic vs. Local ControlNeuronal orHormonalNeuropeptide Y- Acts by reducing IP3 levels-decreases coronary blood flow-decreases heart contractility24Circulatory System RegulationExtrinsic vs. Local Controlstretchtemp.O2CO2pHadenosineK+Decreased O2 levels withopposite effect in lungs25Circulatory System RegulationExtrinsic vs. Local Control(12-45)-Vasodilation-Relaxation-Viagra acts by blockingbreakdown of cGMPNO (nitric oxide)Released fromvascular endothelium:26Circulatory System RegulationExtrinsic vs. Local Control-VasodilationHistamineReleased in responseto injury of connectivetissue and leukocytes:27Chapter 13Gas exchangeAcid-base balance28Gas composition in air O CO N% of dry air 21 0.03 78pp at 760 mm Hg 159 0.23 594380mmHg (at 6000m) 79.6 0.11 297Solubility in water (ml/L) 34 1,019