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Organismal Phys Final Review.docx

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Department
Biology
Course
Biology 2601A/B
Professor
Graeme Taylor
Semester
Fall

Description
Finals – Organismal Phys Lecture 13 –The Heart, Blood and Oxygen association curves (Dr. Taylor) Recap: last lecture – our core temperature is higher than the thermoneutral zone (for all endothermic homeotherms) Closed Circulatory System: Heart: A discrete pumping structure that drives the flow of blood Organisms can have: Single chambered Two or more chambers Multiple Hearts e.g. annelid worm – has a closed circulatory system but no heart! – has expanded muscular vasculature to pump blood around e.g. crayfish - an open circulatory system, with a weak heart, and has muscles involved with pumping blood around the body - in us humans, the muscle is very powerful and does a lot of work.. Muscle tissue of the heart is known as myocardium (in humans specifically) The heart is a muscle with unique structural and physiological properties - remember there are three types of muscles (skeletal, smooth and cardiac) - myocardium is similar to cardiac muscle in that it is striated (thick and thin overlapping filaments), but it is not arranged in a serial pattern Image: pericardium – membrane over the heart parietal (outer) pericardial cavity visceral (inner) myocardium – highly compact and dense endocardium Heart (myogenic and Neurogenic) systole – as it contracts diastole – as it relaxes - neurogenic ->stimulated by nerves - myogenic -> if you strip away the heart’s nerves, it will still beat! (in humans) - there are other animals though, if you strip away the nerves of the heart will not have the ability to beat e.g. crayfish – they have a neurogenic heart (relies on nervous imput) a most important aspect is the volume of blood it pumps per unit of time Cardiac Output = heart rate x stroke volume (CO = HR x SV) human HR ~ 60-180bpm & SV ~ 70-120 Mouse HR ~ 600bpm E.g. Whales have a massive heart – beats about 6bpm Why is there such a difference in heart beat between a mouse and whale?!  there is an allometric relationship with its aerobic activity, so in order to compensate for a smaller heart it has a high heart rate (with all small mammals) What is our heart volume?  5L/ min -- ~ 7000L in a day Image: Resin heart showing the amount of capillaries that surround it Coronary circulation of the human heart Highly resistant to fatigue and loaded with mitochondria Where did the heart come from? – Evolutionary orgin  looking at the heart of a fish; A teleost heart: - single chambered heart, - remember fish have 4 gills on each side - looking at the coronary arteries that feed the heart - as the blood comes in, it goes through a pocket (interconnected canals) which are perfused with blood and then oxygenated ( not necessarily effective but reasonable) - from the great veins (from body – depleted of oxygen)  sinus spinosus  atrium; weakly muscular, gets blood into the ventricle  ventricle  spongy myocardium; this is how the heart gets the oxygen  bulbus arteriosus; elastic and damps pressure oscillations that are created by the systole and diastole - not called that in all fish  in cartilaginous fish (sharks, rays, skates)/ large fish/ lung fish  called cornus arteriosus – and very muscular - muscle aids in pumping blood Fish circulatory system: From heart  ventral aorta  goes across efferent gill vessels  coming into efference?  then head and body into systemic system What does this mean physiologically (in terms of pressure?)? - not very muscular like our system – just a single ventricle -5kPa – pressure of blood exiting heart to the gills - BIG loss of pressure across the gills, low(ish) flow rate through tissues - 3kPa after exiting gills the 4 gills  body and head (conversion kPa = 7.5mmHg) - it loses pressure 1. Bc of length of vessels 2. Fact that there is a large increase in the total diameter And thus sluggish rate/ slow moving in tissues - and it doesn’t circle back to heart - it’s dependant on pushing the blood throughout the entire body and pass the capillary networks of the systemic tissue - fish hearts vary in relative size; thus the pressure difference varies among the fish - e.g. non athletic fish (have to dart out only for fish) vs. athletic fish (salmon and tuna) wim non stop Table: Comparing fish and other mammals – closed circulatory system: Human BP 120/80, CO 80-90 Horse is more 180/110 VS> FISH - catfish 40/30 VS> FISH - Dogfish (cartilaginous fish) – a little lower @ 30/24 Remember, high pressure systems in crabs what was the BP? ~ 50mmHg (diastole) High performance fish hearts: - so for active fish there is variation in the myocardium perfusing oxygen in blood - thus they have a system similar to ours, where oxygenated blood is pumped through part of the tissues (in the compact myocardium muscle tissue) - myocardium still has a bit of spongy tissue- where the blood flow is oxygenating some of that muscle as it’s coming in Deoxygenated blood perfusing spongy myocardium is a limiting factor for fish This creates some strain on them as the blood supplys oxygen to the body, and as that deoxygenated blood comes back it must supply the heart Salmonids, Tuna and Sharks have a “hybrid heart” O2 delivery to octopus muscle Octopus is a highly active closed circulatory invertebrate system, with vessels that perfuse the muscle tissue of the heart The Heart and Major Arteries All endotherms (mammals, birds etc.) have: Muscular, thick elastic walls (smooth muscle and elastin) High Pressure of 10-20kPa Elastic Dampens pressure differences Stores some elastic energy ~ potential energy e.g. Aorta, carotid artery, femoral artery (16/10 kPa) Pressure drop across vascular system – IMAGE OF GRAPH (from last lecture) - large drop in pressure across the arterioles!! - starts at 100mmHg, and drops all the way to near 0mmHg at the veins! Thus a huge drop in pressure - red line = difference in diastolic and systolic (the average is the black line) – difference in pressure buffers to average out by the time it hits the arterioles Veins (in contrast to arteries) Low pressure system Have a system of one way valves; to stop back flow of blood Much thinner-walled and larger than arteries – thus, veins act as a reservoir for blood (and in a sense oxygen) Gravity and pressure -giraffe Vs.and wattle seals (can deep dive to ~600m) – the change in pressure is LARGE (1atm/10m) Gravity also affects pressure ΔP = ρgΔh Ρ – fluid density (mercury > seawater> water>oil) G- acceleration due to gravity Δh – height difference across the system The problem of being a giraffe The brain (NEEDS O2) of a standing giraffe is 2m/ 5 feet above its heart To maintain a pressure of 13kPa in brain arteries, it neds an aortic pressure of c.29kPa/ 220mmHg!!! Q: how do they get blood to the brain?? With the large height difference, and extreme effect of gravity? Large heart (large left ventricle) Fast heart rate (~170bpm vs. recall: whale ~6bpm) Tight skin on legs (creates pressure to force blood back up) Muscular arteries High interstitial fluid pressure, thus efficient return of venous blood Giraffes have a drinking problem Head goes from being 2m above heart to being 2m below it! V. high pressure blood into brain Blood can pool in brain Solving the giraffe drinking problem Vasodillation in lower body reduces BP Elastic arteries near brain absorb some increased pressure One-way valves in jugular vein prevent backflow of blood into head ONE MORE PROBLEM in delivering O2 to the body - good: we have closed circulation, a good pump (the heart) NEED  oxygen to get into the blood – needs respiratory pigments to do so, as the lungs do not have a high enough partial pressure for the blood to simply diffuse by a concentration gradient Lecture 16 – Blood and Oxygen association curves (Dr. Taylor) Recall: when animals become too large to rely on diffusion alone, the solution they have include ventilations systems externally and circulatory systems internally to carry respiratory gases to and from the metabolizing tissue Blood The simplest way to move respiratory gases is by dissolution Oxygen will move along a gradient in the blood to the active tissue where oxygen is being consumed However, the quantities of gas that can be moved around in this way will be limited by the solubility of the gas concerned Gases dissolve in liquids Not the same as having air bubbles! – they (liquid and gas) are equal to each other @ diffusion P liquidproportional to air Amount of gas in solution depends on (x3) o Temperature (as temp ↓, both resp gases (O2 and CO2)↑ solubility) o Salinity (↑ = ↓ solubility of gases) o Gas (* CO2 has a high solubility, while O2 has low solubility!) - blood of a marine animal (at 20°C ionic composition of salt water) (#’s not testable) can hold ~5.5 L of O2  vs. ~159L of CO2 (~29fold increase in CO2 compared to oxygen solubility!) - O2availability + CO2, and their exchange – serious problem for - large animals with a high metabolic rate - tiny animals (especially when they encounter anoxic/ low O2 condition) Blood must be thicker than water Solubility of O2 in water (especially warm salty water like blood) is not enough to provide O2 to active tissues – although a little will enter via diffusion Many organisms use respiratory pigments to bind O2 and transport it to tissues Respiratory pigments - IMAGE Once the respiratory pigment binds O2 (diffusing from air into blood across blood capillaries), that oxygen is no longer in solution Thus, the partial pressure (PO2) is lower than it would be without resp. pigaments in the blood, allowing more to diffuse across (and thus more to bind the pigment)  allows concentration gradient to always be in place What it means to have a respiratory pigment Species Total O2 carrying capacity (ml O2/l) water ~6.98 Blood (bony fish e.g. Tuna) ~197  That is ~ 29x ↑ in carrying capacity of O2 given respiratory pigment What is means to have a respiratory pigment - thus the pigment extracts oxygen in fish allowing dramatic changes in partial pressure over the distance over the blood vessels *recall – mentioned in lecture: fish = countercurrent system, humans = tidal system, other systems: crosscurrent and concurrent Can not only suck a lot of O2 out of water, but can transport a lot per unit volume as well Respiratory Pigments Can be in solution (in some animals, not in RBC), or enclosed in blood cells (like us!) Hematocrit: - centrifuge whole blood and measure proportion of “solids” (=cells) - get plasma (WBC/platelets) at top - bit of “buffer zone” - and the rest = RBC/ hematocrit – hold pigment (respiratory pigments – colored bc heme group) - a pretty good measure of blood O2 carrying capacity in vertebrates Components of a respiratory pigment 1. Protein (four subuni2α,2β) – tetrameric with us ~can vary with animal 2.Metal-containing “Heme” group – site of O2 binding – held on by nitrogens - inside a single RBC ~ 250 MIL oxygen binding sites, x4 ~ a billion in ONE RBC! Why are RBC unique?- why don’t they use up the oxygen?? - don’t have nucleus or mitochondria – thus don’t deteriorate the O2 Do RBC divide? Where are they produced? - produced in the bone marrow, and many die and are born everyday Kinds of respiratory pigments: Pigment Color Structure O2Binding Hemoglobin Dark Red/Blue Protein + 1/Fe2+ Heme + Fe2+ Chlorocruorin Green Protein + 1/Fe2+ Porphyrin + Fe2+ Hemerythirin Violet/ colorless Protein + 1/2Fe2+ Fe2+ Hemanocyani Blue/ colorless Protein + 1/2Cu2+ n Cu2+ Chlorocruorins (ChLs) – the green hemoglobins Found in four polycheate families Two important ones are: - Serpulidae (Christmas tree worms) – anterior end seen in pic, the posterior end is in a “chew?”e.g. coral. Good to have blood in a chew, because it potentially lacks oxygen (anoxic state) when it withdraws into that chew Of Phylum  annalididae (ring worm) - Sabellidae (feather duster worms) Hemetrythirins -Sipunculida ~ peanut worms - Praipulida ~ penis worm (WTF) - Brachiopoda  not molluscs; but has 2 shells Hemocyanins -some arthropods - many molluscs  their origin, even though similar, are separate and structurally different! -thus referred to as arthropod hemocyanin, and mollusc hemocyanin Hemoglobins - most widely distributed respiratory pigment in the animal kingdom - traces are found in protists and plants In chart have protostomes vs. deuterostomes (BIG CLADES) - Hb are found sporadically in them both So what is driving the evolutionary pattern? - there is no real reason, - appear as intracellular Hb: 1. Monomers, 2. Dimmers, 3. Tetramers - or as extracellular: 4. Polymers (get very large) Hb Oxygen association curve - Full saturation is at the respiratory surface (e.g. gill/lung) Why is it a sigmoid curve? Cooperativity -mechanism that causes the curve - cumulative increase in affinity as 2 binds to the heme groups - subunit changes conformation slightly, increasing affinity of other heme groups in that tetramer - subunit interaction - so if one O2 is added, it is the subunit (NOT the heme) that changes conformation and allows more O2 to be added more easily Affinity can change - The human myoglobin ( similar to Hb and stores O2 in muscles cells), is a monomer with a single heme group, and does not have that sigmoid curve (it has either full saturation, or drops down) – thus has a high affinity for oxygen – thus wants to hold on to the oxygen – thus acts more like a storage mechanism - vs. Hb relative to myoglobin has a low affinity - start journey FULLY saturated in the lungs at the top - the less steep slope, needs a bigger drop in partial of the curve pressure for O2 concentration changes, thus is said to have - for every 5% drop in O2 concentration (as it is a higher affinity for oxygen – similar to myoglobin (acts like released), the partial pressure of O2 changes O 2torage) dramatically, then smaller and smaller changes. - The steeper slope has a lower affinity for oxygen (like Hb) - allows for O2 to be held really tightly at the lungs, and then released where is needed - thus there is flexibility in the affinity of the respiratory pigment for oxygen The Bohr Effect/Shift Exercising tissues produces CO 2 As P CO2 increases (and pH decreases = more carbonic acid), affinity of Hb decreases This allows more O to2be unloaded at sites where it is needed (places with high metabolism creating more CO2) Affinity is still high at the blood-gas barrier for initial O2 uptake - Decreasing the pH, causes increased sigmoidal curve, thus Hb has less affinity for O2 – thus releases it at areas needed and enhances O2 delivery (where there is a high CO2 – causing the acidity) Does CO2 bind to Hb? Short answer: No Long answer: Yes - Hb doesn’t drop off an O2 and pick up a - CO2 binds to the Hb molecule (but not at CO2 to return to the lungs the heme group) - Most transport of CO2 is in solution (and - This binding alters the conformation of the often as carbonic acid/bicarbonate) protein (and contributes to the Bohr effect) - But it isn’t the main means of CO2 transport Other modulations of O2 affinity ↑ temp = ↓ O2 affinity Metabolic products, e.g. ↑2,3-DPG = ↓ O2 affinity Inorganic ions? - = ↓ O2 affinity - E.g. chloride ion used by bears and ruminant animals, - the blue crab (portunus sapidus) – sequesters Ca2+ to change its affinity for oxygen and when it encounters anoxic environments. So it uses the ca2+ to change the curve. * note 2,3,diphosphoglycerate = DPG The Root Effect A change in the amount of O bo2nd at saturation, not (just) in affinity - in most situations you want the blood to be fully saturated with oxygen at the respiratory surface, the root effect lower this Driven by pH Used by fishes To offload O2 against gradients to fill swim bladder To supply O2 to oxygen-demanding retina (have very little capillaries) - drop in y-axis = root effect Myoglobin Neuroglobin Cytoglobin Monomeric A monomeric globin found in muscle Discovered recently (2000) Discovered in 2002 (esp. heart) Monomeric, high O2 affinity Apparently present Has a higher O2 affinity than Hb Present in brain and retina in all cells A sort of oxygen store for the cell of humans Also monomeric? Protection from hypoxia (low O2) Lecture 14 – Water and Fluid Transport: Moving fluid in plants Plants need a circulatory system to deliver Sugars from the leaves to other tissues Hormones and signals throughout the organism Water and nutrients from the soil to the leaves Xylem and Phloem Xylem Phloem - translocates water and inorganic nutrients - translocates sugars, proteins, and signalling - from roots  leaves molecules - from source tissues (e.g. leaves)  sink tissues (e.g. roots) - made of tracheids and vessel elements - these are dead cells that can interconnect: - laterally (both) - edge to edge ( found with tracheids) - end to end (found with vessel elements) - supported by fibres and other lignified cells (in trees) Vessel Elements Primary vessel type in angiosperms End to end stacking plus perforation plates = continuous tubes Pits (found on sides of v.elements) connect vessel elements laterally Some lateral movement (but slower than vertical movement) Tracheids Secondary in angiosperms Primary vessel type in gymonosperms - have permeable pit membranes (on sides) – also allow lateral movement to long conncected vessels How do I know it’s a circulatory system? Pump Fluid Vessels or spaces But there’s no pump?! Sometimes, root pressure can push water into xylem Water is usually pulled The physics of pulling fluid through tubes Evaporation creates low pressure at the plant periphery (leaves) Water is thus pulled from a high pressure (in the ground) through tubes up to the low pressure Cohesion-tension theory Evaporation at the leaves causes negative pressure The cohesive properties of the water molecules transfer this tension through the length of the water column Requires a continuous water column This is a lot of tenstion Thu
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