Class 8 Pumps and Tubes PDF

Pumps and Tubes Class 8 What are some of the physical and physiological reasons for the evolutionary diversity of circulatory systems? How do the processes of small scale flow connect to large scale flow in the operation and functi...

Pumps and Tubes Class 8 What are some of the physical and physiological reasons for the evolutionary diversity of circulatory systems? How do the processes of small scale flow connect to large scale flow in the operation and function of circulatory systems? How do evolution and physics intersect in the development of hearts? www.vanderbilt.edu/hillyerlab/Research__Circulation.html s1113.photobucket.com  Pumps and Tubes What are some of the physical and physiological reasons for the evolutionary diversity of circulatory systems? www.vanderbilt.edu/hillyerlab/Research__Circulation.html s1113.photobucket.com  Why do animals need a heart? Do all animals have one? Diffusion is only effective at very small scales, for larger scale molecule movement we need bulk flow bulk ow = uid movement caused by pressure gradients Organisms need bulk flow…. To deliver key nutrients to every single part of the body. To remove wastes from every single part of the body. cdn.society6.com fl fl  Phylum Cnidaria Body nutrient squeezers: animals without hearts Are they limited? Evolutionarily constrained? Phylum Cnid Why do organisms need bulk flow? Animals To deliver key nutrients to every single partwith of theabody. large surface area To remove wastes from every single part of the body. and a lot of muscular movements…. at happens when nutrients are not delivered and wastes are not removed? areThis The part without delivery dies. doing great without a is serious! heart! Phylum Phylum Platyhelmint Body nutrient squeezers: animals without hearts Platyhelminthes Are they limited? Evolutionarily constrained? Otherwise…. make a dedicated pump!!! 2015 16 2/3/2015 www.ucmp.berkeley.edu OPEN CIRCULATORY SYSTEM Phylum Arthropoda Pumping tubes generate the flow en.wikipedia.org At the periphery, the blood ows freely into the interstitial space between the shell and the organs. fl The circulatory fluid in open circulatory systems, called hemolymph, is pumped by the heart though vessels but then exits the vessels into a body cavity where it directly bathes the organs for nutrient As the heart beats and the animal moves, the hemolymph circulates around the organs within the body cavity and then reenters the heart. https://commons.wikimedia.org/wiki/File:Open_circulatory_system.svg Hemolymph returns to the blood vessel through openings called ostia.  Open circulatory system What are the disadvantages? The open peripheral system limits the size of the animals (insects and spiders), because the interstitial diffusion is efficient only over short distances. What are the advantages? Despite the low pressure of the open systems, by lowering the resistance the flow rate increases rapidly. en.wikipedia.org  Blood ow through the tissues of an insect is principally through lacunae and sinuses. In general, the blood of insects lacks a respiratory pigment. The modest development of the circulatory system in insects seems paradoxical at rst. Insects have a lesson to teach: the circulatory system can remain quite simple in even highly active animals if it doesn’t have the burden of O2 transport. (From J. C. Jones. 1964. In M. Rockstein [ed.], The Physiology of Insecta, vol.3, pp. 1-107. Academic Press, New York.) fl fi  Let’s close up the pipes…. Annelida Philum Closed circulatory system Multiple pseudo-hearts These pseudohearts don't pump blood, but rather squeeze vessels to help circulate blood throughout the worm's body weed-science-classes.wikispaces.com; en.wikipedia.org  Closed circulatory system What are the disadvantages? In a closed system, the blood is required to travel through exceedingly small diameter vessels to complete its circuit through the body. These tiny vessels present a high resistance to ow. Thus, in a closed system, for blood to circulate at high rates, large pressure di erences are required. What are the advantages? With a closed circulatory system, the spatial distribution of blood ow can be nely controlled on very short timescales. It is more e cient in that it uses less blood for even higher and faster levels of distribution, supporting higher metabolisms and physical activities. weed-science-classes.wikispaces.com; en.wikipedia.org fi ff ffi fl fl  Pumps and Tubes How do the processes of small scale flow connect to large scale flow in the operation and function of circulatory systems? www.vanderbilt.edu/hillyerlab/Research__Circulation.html s1113.photobucket.com  General characteristics of circulatory systems The three important components: Pump/s or other propulsive structures to drive uid ow A system of tubes, channels or other spaces through which the uid can ow A uid that circulates through the system fl fl fl fl  The physics of ow through tubes: Ohm’s law Ohm’s law ΔP = Flow x Resistance V = IR Electrical current: a ow of charged particles Flow of blood in the bloodstream. Electrical potential di erence, the driving force for electrical current Pressure di erence (ΔP) generated by the heart between arteries and veins. Electrical resistance Hydraulic resistance www.themeasureo ife.net fl fl ff fl ff  The key to circulation, however, lies in the tubes. The arrangement of vessels in the organism is influenced by general physical laws as well as by specific physiological requirements. www.leememorial.org  The physics of ow through tubes: Poiseuille’s law What factors determine the resistance? Ohm’s law 3 factors determine the resistance: - viscosity of the blood ΔP = Q x R - length of the vessel Q = ΔP/R - radius of the blood vessel. R= 8ηl/πr4 Flow increases with the fourth power of the radius! Poiseuille's Law If the radius of the lumen is reduced to a half what would be the change in the new rate of ow? The rate of ow falls to 1⁄16 of the original rate! fl fl  The physics of ow through tubes: Poiseuille’s law Poiseuille's Law Ohm’s law Flow increases with the fourth power of Q = ΔP/R the radius! O2 Lungs Problem: In the lungs and systemic tissues Pump O2 is delivered by diffusion. For an effective diffusion we need small tubes O2 Tissue fl  In the lungs and systemic tissues O2 is delivered by diffusion. For an effective diffusion we need small tubes Solution: O2 Lungs Big tubes for delivery and O2 small tubes for diffusion …one more problem: What happens when you place a finger on the garden hose? Pump O2 Tissue O2 VELOCITY OF WATER INCREASES! For an effective diffusion we need both small tubes and low velocity of flow.  The physics of ow through tubes: the principle of continuity Flow in = Flow out Q= A ∗ v Q1=Q2 A1v1=A2v2 If the area of the tube decreases the speed of the fluid must increase. Solution: branching the vessels increases the total cross-sectional area! boundless.com fl For an effective diffusion we need both small tubes and low velocity of flow! The total cross-sectional area of the vessels increases with distance from the heart. Q= A ∗ v Q1=Q2 A1v1=A2v2 Consequently, the velocity of flow decreases, and then increases after passing the capillaries. boundless.com www.allaboutcircuits.com www.pdn.cam.ac.uk Q = ΔP/R What are the bene ts? Lungs Lungs Pump Pump Tissue1 Tissue2 Tissue1 Tissue2 Tissue3 Tissue3 With tissues in parallele we can change the pattern of flow by varying the relative resistances, and we can reduce the pressure that has to be developed by the heart. fi  A physiological model involving a parallel circuit We can change the pattern of flow by varying the relative resistances of the different organs, by selectively vasoconstricting or vasodilating the arterioles. We can reduce the overall resistance of the circulation (TPR). www.pdn.cam.ac.uk www.pdn.cam.ac.uk Slideshare  A physiological model involving a circuit in series For a series resistance network, the total resistance (RT) equals the sum of the individual resistances. Therefore, for the vessels depicted in the gure, the total resistance is equal to the sum of the small artery (RA), arterioles (Ra), capillaries (Rc), venules (Rv), and vein (RV) resistances. RT = RA + Ra + Rc + Rv + RV The biggest drop in blood pressure in the circulation occurs across the vessels with (collectively) the highest resistance: the arterioles. This has considerable importance when you come to consider the control of the circulation. fi  Single vs double circulation Single-Loop Circulation: blood passes through the heart only once on each circuit Double-loop circulation: are circulation systems in which blood ows through the heart twice. 1 Heart vs 2 Hearts! http://esi.stanford.edu/circulation/circulation6.htm fl  Pressure drops as it reaches High pressure to deliver blood to the tissues, the tissues. and a low pressure to the lungs. Lungs Lungs Pump Pump1 Pump2 Tissues Tissues What are advantages and disadvantages of single vs double circulation? In fish pressure drops as it reaches the systemic circulation. In mammals we can have a high pressure to deliver blood to the peripheral tissues, and a low pressure to the pulmonary circulation…and so we don’t blow out the lungs!  Single vs double circulation Tissues Are lungs and tissues in series or in parallel? In fish the two circuits are in series, and so the flow through them must be exactly the same by the principle of continuity. Tissues This is the same for a fully separated 4-chambered heart like mammals. The difference is in the pressure! http://esi.stanford.edu/circulation/circulation6.htm  In Amphibians the blood is pumped from a three-chambered heart with two atria and a single ventricle. The “two hearts” involves just a single ventricle that produces pressure for both the pulmonary and systemic circulations. The ow through the two circuits depends on the resistance of each. The resistance can be changed independently for each circuit through vasoconstriction. fl Most reptiles also have a three-chambered heart that with a single ventricle produces pressure for both the pulmonary and systemic circulations. Unique cardiac anatomy of crocodilians - a four-chambered heart with the dual aortic arch system  Circulatory system of cephalopods (squids and octopus) Figure 25.21 The circulatory plan of squids and octopuses (Part 1) Physiologically the circulatory system of squids and octopus resembles that of vertebrates more than other mollusks. And the arrangement of hearts is closer to that in mammals than fish.  ference is significant and must be considered when us (M. Hammer), who found it in a poorly ing three-dimensional (3D) structures within the genesis. A sep comparing estimates of 'OH(n/'OH(s. For example, in referees; and the technical assistance of A. Clarke, consolidated channel sandstone exposed in the concretion. Patterns of shapes and radiodensi- visible indicat Downloa upper half of the Hell Creek Formation (Maas- ties were found to resemble a four-chambered the geochemic the model described in (8), 'OH(n/'OH(s & 1.00 R. Myers, T. Conway, P. Lang, and N. Paynter. trichtian) in Harding County, northwestern heart (Figs. 1 and 2). Two adjacent cavities been well stu Case Study when the boundary between the hemispheres is set at the equator; this ratio decreases to 0.87 when the Samples were obtained from PSA with assistance from NOAA’s Carbon Cycle group. Supported side South Dakota, USA. The extremities and left in of theis skeleton were lost to erosion. The surrounded by iron-rich walls are readily appar- ent, connected to a dorsally arched tube in a served in the p preserved thro www.prehistoric-wildlife specimen otherwise very well preserved and position that is topologically appropriate for a whereby musc Southern Hemisphere is defined as 8°N to 90°S (that part by the Atmospheric Chemistry project of the contains abundant evidence of tissues that usu- systemic aorta. The thicknesses of the walls de- conditions (12 ally decay, such as sternal ribs and cartilaginous limiting the cavities are consistent with those of The presum is, when one additional model segment, 0° to 8°N, is NOAA Climate and Global Change Program. C.M.S. plates attached to caudal surfaces of thoracic ventricles and an interventricular septum, the re- the left ventric included as being part of the Southern Hemisphere). acknowledges the support of NSF through grants ribs. The skeleton closely resembles that of the lative dimensions of which would vary with the 27 mm in diam hypsilophodontid Thescelosaurus (6), and its degree of distension of the heart at death. The no indications 31. J. Rudolph, A. Khedim, R. Koppmann, B. Bonsang, J. NSF-ATM-9320778 and NSF-ATM-9903529. gracile dentary separates it from fragmentary atria are usually very thin-walled compared to aortic arch. If Atmos. Chem. 22, 67 (1995). material of the closely related and sympatric the ventricles and often collapse at death, oblit- crocodiles, the Bugenasaura (7). The circumference of the erating their internal cavities. They are not reli- 32. J. Rudolph, personal communication. 7 December 1999; accepted 10 March 2000 femur (197 mm) suggests a body weight of 300 ably discernable in the specimen, nor are the kg (8), and the length of the femur (468 mm) small vessels that are expected in the region of scales to a total body length of 3.9 m (9). A the putative heart base. A radiolucent area imme- Downloaded from http://science.sciencemag.org/ on February 23, 2017 Cardiovascular Evidence for an Intermediate or Higher Metabolic Rate in an Ornithischian Dinosaur 1* Paul E. Fisher,. 1. Right lateral view of a 3D reconstruction Dale of CT images Russell,2 specimen Fig. 2. Enlarged right lateral view of a 3D A. Thescelosaurus of the owing the right (R) and left (L) ventricular3,cavities, preserved sternal4 ribs (S), and plates reconstruction 5 of CT images of the same spec- embling uncinateMichael processesK.(U)Stoskopf, Reeseribs. attached to thoracic E. The Barrick, apex of Michael Hammer, the heart has been imen showing the systemic arch (SA) and right mporarily removed. Andrew A. Kuzmitz6 (R) and left (L) ventricular cavities. Computerized tomography 21 APRIL scans2000 of a VOL 288 SCIENCE ferruginous www.sciencemag.org concretion within the chest Fig. 1. Right lateral view of a 3D reconstruction of CT images of the Thescelosaurus specimen Fig. 2. Enlarg region of an ornithischian dinosaur reveal structures that are suggestive of a showing the right (R) and left (L) ventricular cavities, preserved sternal ribs (S), and plates resembling uncinate processes (U) attached to thoracic ribs. The apex of the heart has been reconstruction imen showing four-chambered heart and a single systemic aorta. The apparently derived temporarily removed. (R) and left (L) condition of the cardiovascular system in turn suggests the existence of in- 504 21 APRIL 2000 VOL 288 SCIENCE www.sciencemag.org termediate-to-high metabolic rates among dinosaurs. Fossilized Heart Shakes Up Dinosaur Theories The three-chambered heart of modern reptiles paired systemic aortas arising from the ventricle (except crocodiles) includes a single ventricle and distributing blood to the body. In contrast, Detailed, that pumps blood both to thecomputerized lungs and to the X-ray the scansheart four-chambered of the 66-million-year-old of modern birds and fossilized heart remainder of the body. In crocodiles, the ventri- mammals has two completely separated ventri- show that its muscular cle is composed of two chambers that are in- chambered-heart cles and a single systemic may be similar aorta, ensuring that to mammals and birds. completely separated from each other function- only completely oxygenated blood is distributed ally by the foramen of Panazzi. Thus, in all to the body. These modifications to the cardio-  Pumps and Tubes How do evolution and physics intersect in the development of hearts? www.vanderbilt.edu/hillyerlab/Research__Circulation.html s1113.photobucket.com  Why did the circulatory system evolve? …most certainly evolved to overcome the time and distance constraints of diffusion, thus permitting increased body size and metabolic rates The movement of uid in blood vascular systems was originally mediated by the peristaltic motion, but the appearance of true hearts in which in ow and out ow are tightly coupled via multiple chambers, e cient electrical connection and one-way valves would have helped with the increased body size, metabolic activity and the transition from aquatic to terrestrial life. Rita Monahan-Earley,Ann M. Dvorak, and William C. Aird, J Thromb Haemost. PMC 2017 ffi fl fl fl What do you need in order to build a biological heart? Raise your hand when you have three key building blocks. contracting cells - Drosophila Tinman controls heart development. - Mouse Nkx mutations cause cardiac defects. - Amphioxus uses Nkx/Tinman homolog during heart development. - Nematodes (C. elegans) don’t have a heart, but the pharynx contracts rhythmically using ceh-22 gene which is homologous to Nkx and Tinman. - Nematodes with defective ceh-22 gene can have mouse Nkx expressed and regain proper pharynx function. - Hydra (only have a gastrovascular cavity that pumps fluids) express a gene related to Nkx at location of pumping cells. 2/3/2015 en.wikipedia.org; 40 weinterrupt.com; nematode.unl.edu  What do you need to build a biological heart? - generation of positive and negative pressure - development of heart maintains flow with different mechanisms - embryonic zebrafish use a suction pump before valves develop 2/3/2015 ferris.edu; 41 linfishlab.webs.com Forouhar et al (2006) Science  What do you need to build a biological heart? Clas - flow Guid - Biomechanical forces of flow are necessary for Ho cells to develop properly. op - Initiation of heartbeat causes expression of Runx1 in blood stem cells; flow (shear stress) causes this W expression and is necessary for correct heart div development. - Interruption of normal flow patterns causes cardiac Ho defects. Read Key surf ope hem ostia See the movies online: clos http://www.nature.com/nature/journal/v421/n6919/suppinfo/nature01282.html syst 2/3/2015 ferris.edu; 42 linfishlab.webs.com Hove et al (2003) Nature; Adamo et al (2009) Nature  Pumps and Tubes Class 8 What are some of the physical and physiological reasons for the evolutionary diversity of circulatory systems? Role of the Heart. - Open vs Closed circulatory system advantages and disadvantages How do the processes of small scale flow connect to large scale flow in the operation and function of circulatory systems? - How to Build an efficient circulatory system - Hagen–Poiseuille equation - Principle of continuity - Circuits in series vs in parallel How do evolution and physics intersect in the development of hearts? (Case studies) - What you need to build a biological heart? - Contracting cells; pressure gradient, flow.