Evolution of the Circulatory System Sora Choi & Miguel Rodriguez Introduction • Circulatory system solves the problem of energy and material exchange between an organism and its environment • As body types evolved, natural selection favored organism that evolved more efficient means of distribution/exchange • Several ways of distribution in extant organisms Overview • Evolutionary trends in the circulatory system – Maximum organism size – Complexity – Colonization of land – Cephalization • Anatomy of representative animals • Anatomy of representative chordates Overview (cont.) • Control of body temperature in vertebrates via circulatory system – Counter-current heat exchange – Peripheral tissue circulation • Human heart function – Regulation of heart rhythm – Cardiac cycle – Blood pressure Evolutionary Trends (Size) • Bigger size favors more developed circulatory system • Diffusion requires short distances • Time constraints (time α dist2) • Tissue thickness – Complex/thicker tissues have an evolutionary advantage… – Organism with tissues more than a few millimeters thick would not survive with just a GV cavity… Evolutionary Trends (Complexity) • Open vs. closed circulatory systems – Both solve the problem of diffusion distance – Both rely on blood pressure differences – Both consist of three major components • Circulatory fluid (blood/interstitial fluid/hemolymph) • Set of tubing (vessels including arteries/veins) • Muscular pump (muscular vessels or heart organ) Both have advantages and disadvantages… Open Circulatory System Advantages • Lower pressure = lower required energy • Less piping = lower building/maintenance costs (energy) • Can function as hydrostatic skeleton Disadvantages See CCS advantages http://farm1.static.flickr.com/93/233112287_dd39898847.jpg?v=0 Closed Circulatory System Advantages • Higher pressure • Higher efficiency • Higher metabolism • Better at dealing with gravity Disadvantages See OCS advantages http://health-pictures.com/blood/images/blood-circulation.jpg Evolutionary Trends (Cephalization) • Muscular vessels to hearts – Muscular vessels = more rapid/efficient transport of fluid – A muscular heart keeps a regular, “steady” flow circulating throughout the organism – Evolution would favor an organism with a regular supply of nutrients/method of waste exchange etc. (consider breathing) – Brain requires substantial blood flow… Evolutionary Trends (Complexity) • Hearts with chambers – A single contractile mass induces flow “outwards” upon contraction – This flow is instantly reversed upon cessation of pressure – Reversal is not favorable • Inefficient • Mixes blood of varying qualities – Evolution would favor an organism that could segregate the contractile mass Evolutionary Trends (Complexity) • Two types of chambers – Atria • Receive blood from the organism • Smaller, less powerful – Ventricles • Pump blood throughout organism • Larger, more muscular • Varying arrangements evolved (1 or 2 of each) http://www.starsandseas.com/SAS_Images/SAS_Physiol_Images/SAS%20cardiopics/ heart_chambers.jpg Evolutionary Trends (5 of 5) • Double circulation – In organisms with two atria and 1 or 2 ventricles – Combination of 2 and 2 allows for complete segregation of oxygen- rich/oxygen-poor blood • Human beings exhibit a combination of the most complex trends… http://www.dorlingkindersley- uk.co.uk/static/clipart/uk/dk/exp_humanbody/exp_human056.jpg Basic Anatomy - Animals • Porifera • Cnidarian • Platyhelminthes • Nematoda • Mollusca • Annelid • Arthropoda • Echinodermata • Chordate http://i.n.com.com/i/ne/p/2006/CnidarianClouds_400x600.jpg Porifera Cnidaria Platyhelminthes Nematoda Mollusca Annelid Arthropoda Echinodermata Chordata • Sponge – no tissues hence no circulatory system – simple body structure Co Si La Ce http://www-tc.pbs.org/kcet/shapeoflife/imganim/porifera3.jpg Porifera Cnidaria Platyhelminthes Nematoda Mollusca Annelid Arthropoda Echinodermata Chordata • Jellyfish – no true circulatory system – thin body wall encloses gastro-vascular cavity – rely on diffusion across two-cell thick layer Co Si La Ce Porifera Cnidaria Platyhelminthes Nematoda Mollusca Annelid Arthropoda Echinodermata Chordata • Flatworm – no true circulatory system – branched GV cavity – only one opening – branching and flat body shape ensure short Co Si diffusion distances La Ce Porifera Cnidaria Platyhelminthes Nematoda Mollusca Annelid Arthropoda Echinodermata Chordata • Nematode – no circulatory system – tiny size Co Si La Ce http://www.bu.edu/gk12/eric/nematode.jpg Porifera Cnidaria Platyhelminthes Nematoda Mollusca Annelid Arthropoda Echinodermata Chordata • Snail – Open circulatory system • fluid for conveyance • branching vessels • heart muscle to provide pressure – blood + interstitial fluid = hemolymph • bathes organs directly • pumped into spaces surrounding organs (sinuses) Co Si La Ce stolen from http://seabarnacle.piczo.com/?g=50019046&cr=5 Porifera Cnidaria Platyhelminthes Nematoda Mollusca Annelid Arthropoda Echinodermata Chordata Octopus Active predators Highly intelligent Closed circulatory system Co Si La http://www.greenexpander.com/wp- Ce content/uploads/2007/12/octopus.jpg Porifera Cnidaria Platyhelminthes Nematoda Mollusca Annelid Arthropoda Echinodermata Chordata • Earthworm – Closed circulatory system • Same basic parts as before • Blood is confined to vessels – Blood and interstitial fluid do NOT mix • diffusion occurs between blood and fluid (middle- man) – Muscular vessels function as “hearts” Co Si La Ce http://www.infovisual.info/02/006_en.html Porifera Cnidaria Platyhelminthes Nematoda Mollusca Annelid Arthropoda Echinodermata Chordata • Lobster – Open circulatory system Co Si La Ce http://stuff4restaurants.com/blog2/wp-content/uploads/2007/12/blobster.jpg Porifera Cnidaria Platyhelminthes Nematoda Mollusca Annelid Arthropoda Echinodermata Chordata • Grasshopper http:// unive rse- revie w.ca/ I10- 82- grass hopp er.jpg Co Si La Ce Porifera Cnidaria Platyhelminthes Nematoda Mollusca Annelid Arthropoda Echinodermata Chordata • Echinoderms Co Si La Ce http://www.marriedtothesea.com/062406/ATTENTION-SCIENTISTS.gif Porifera Cnidaria Platyhelminthes Nematoda Mollusca Annelid Arthropoda Echinodermata Chordata • Dog (Woof!) – Cardio-vascular system • Similar to earthworm • Muscular heart with chambers – Chambered heart segregates blood • oxygen-rich vs. oxygen- poor Co Si La Ce http://www.dog-health-guide.org/images/dogheart.gif Right Lung Left Lung Right Atrium Left Atrium Right Ventricle Left Ventricle Diaphragm Chest Cavity, Housecat Cattus fattus- Biology 162 Lab – March 26, 2009 • Some Chordates have hemoglobin in the blood • Increase in circulatory complexity • water to land (lungs to increase O2) • Separate pulmonary circulatory loop • Amphibians 3-4 to chamber hearts • Oxygenated to deoxygenated blood Basic Anatomy - Chordates • Urochordata – Blood contains a high amount of lithium and vandium – It consists of a ventral heart and an open circulatory system http://www.mun.ca/biology/scarr/Sea_Squir t.gif Example of Urochordata • Sea Squirt (closed open circulatory system ) – Muscular region which pumps hemolymph – Flow of hemolymph reverses with every contraction – No central heart present http://media.eurekalert.org/release_graphics/ciona.jpg Chephalochordata • Circulation is closed • No central heart is present, but consists of branches. • Main ventral and paired dorsal aorta. • Lack hemoglobin and is colorless. • Have atria cavity • The overall pattern of the circulatory system is distinctly vertebrate # 7 : Circulatory system of the lancelets http://www.answers.com/topic/lancelet http://en.wikipedia.org/wiki/Lancelet Agnathans • Simple two-chambered • Due to the difficulty of heart for blood pushing blood through circulation so many sets of gills, • The heart absorbs lampreys have a heart blood from within itself weight to body weight • As a result, the blood it ratio second only to receives lacks oxygen mammals – thus heart • Hagfishes: six hearts + metabolism relies on open circulatory system lipids and is anaerobic http://eugevir.tripod.com/ca/AgCi.html Blood is pumped out of the ventricle to the gills, S whence it travels to the This diagram shows rest of the body, and then the basic blood returns to the atrium, from flow of Agnathans, which it is pumped to the which has a 2- chambered heart ventricle and then back to the gills A dissection of the circulatory system of a lamprey. http://eugevir.tripod.com/ca/AgCi.html Basic Anatomy • Chondricthes (sharks) • The circulatory system • Two chambered heart invades the • Closed Circulatory System cartilaginous matrix. • The difference b/twn Chondricthyes and Osteichthyes is that chondricthyes have This permits the local skeletons made of cartilage, not bone osteoblasts (bone- – Osteichthyans (bony forming cells) to fish) continue bone • In lower vertebrates, cartilaginous formation within the structures can cartilage and also become superficially recruits additional, calcified . Bony fish circulating osteoblasts. are different Single circulation in fishes • Salmon – Two chambered heart (derived from Chondrichthes) – Single circuit of blood flow – gills to the body back to the heart. Single Circulation The blood passes through the heart once in each complete circuit Blood entering the heart collects in the atrium before transfer to the ventricle. Contraction of the ventricle pumps blood to the gills where there is a net diffusion of O2 into the blood and of CO2 out of the blood. As blood leaves the gills, the capillaries converge into a vessel that carries O2 rich blood to capillary beds throughout the body When blood flows through a capillary bed, blood pressure drops significantly, but when animals swim, their contraction+ relaxation of their muscles help pace circulation in the blood Amphibians Frog Three-chambered heart (two atria and one ventircle) Two circuits of blood flow (adults) (pulmo-cutaneous and systemic) The gas exchange occurs both in the lungs and skin capillaries Breathe in the water. Basic Anatomy - Amphibians • Relatively little mixing of oxygen-rich / oxygen- poor blood occurs in the single ventricle (clean) – A ridge within the ventricle diverts most (90%) of the O2 poor blood from the R- atrium into the pulmocutaneous circuit and most of the O2 rich blood from the L-atrium into the systemic circuit. Iguana • Three-chambered heart • A septum partially divides the single ventricle reducing mixing of oxygen-rich and oxygen- poor blood. • Gas exchange only occurs in the lungs • Because their skin is no longer exchanging gas from the environment, the iguana is similar to the frog. Humans • Four-chambered heart – Segregates oxygen-rich and oxygen-poor blood – Gives higher blood pressure – O2 rich blood and O2 poor blood do not mix • Two ventricles & atria. http://www.cptc.edu/library/Bio%20118%20L http://www.uaf.edu/pair/physics ecture%20Notes%20Rev%200105_files/ima /images/circulation.gif ge139.jpg http://universe-review.ca/I10-82- circulatory.jpg http://www.uaf.edu/pair/physics/images/circ ulation.gif • Fishes – Single circulation – Two chambered heart • Amphibians – Double circulation – Three chambered heart • Reptiles (Except Birds) – Double circulation – Three chambered heart • With a septum partially dividing the single ventricle – In Crocodilians, the septum is complete and the heart is 4- chambered • Mammals – Dual circuits operate simultaneously – The two ventricles pump almost in unison • Some blood traveling in the pulmonary circuit, the rest of the blood is flowing in the systematic circuit http://www.uaf.edu/pair/physi cs/images/circulation.gif Body Temperature Regulation • Counter-current heat transfer – involves an “anti-parallel arrangement of blood vessels” known as a countercurrent heat exchanger. – arteries and veins are placed near each other – Warm blood goes through arteries, it transports heat to the colder blood returning from the boundaries in the veins. • Dolphins and geese are examples of a countercurrent system as well as sharks, bluefin tuna, swordfish, bumblebees, honeybees, and some moths. Body Temperature Regulation • Peripheral tissue circulation – Sweating/ bathing moisten the skin enhance evaporative cooling. – Many terrestrial mammals have sweat glands which are controlled by the nervous system. – Animals have hair, fat and feathers. • vasodilation/vasoconstriction – increase in the diameter of superficial blood vessels Body Temperature Regulation • Vasodilation cont. – affect the surface of the body – increases the blood flow • Vasoconstriction – Reduces blood flow and heat transfer by decreasing the diameter of superficial vessels – Ex. jackrabbits avoid overheating on scorching, and desiccated days. Heart Rhythm Regulation • SA node – Wall of right atrium – Origin of impulse (myogenic) • AV node – Wall between RA/RV – 0.1 second delay • Two nerve sets compromise to control rate • Hormones/body temp. also influence rate http://health.howstuffworks.com/heart4.htm Cardiac Cycle • One complete sequence of pumping and filling (contraction and relaxation) • Atrial contraction fills ventricles • Atrial relaxation allows some blood to return while > • Ventricular contraction pumps blood to lungs/body • Ventricular relaxation allows for filling from atrial contraction Blood Pressure • Ventricular contraction creates pressure in the arteries • This pressure travels throughout body and is felt as the pulse • Systolic pressure = “active pressure” • Diastolic pressure = “passive pressure” Human Heart Physiology Hope this works http://www.metacafe.com/watch/2342286/human_heart_functioning_3d_model/ Questions ???