Pt 7 Animal Cardiovascular and Respiratory Systems

How has the circulatory evolved through time?

• Evolution 

  • Unicellular -> multicell 

    • All use oxygen (aerobic resp) to exchange oxygen with CO2 in env 

    • Water: in tissue there is CO2 -> exchanged with oxygen 

  • All devised method to exchange gases 

    • Core = diffusion 

• Circulatory system 

  • Exchange of gases supported by circulatory system -> work together for respiration (exchange gases) 

  • Unicellular is smaller -> simple diffusion allows gas exchange 

    • simplest invertebrate animals were composed of thin sheets of cells with a large surface area.

• Multicellular have more body surface area -> needs more -> developed integrated system of gas exchange (respiratory system) 

What is the respiratory system?

• Multicellular have more body surface area -> needs more -> developed integrated system of gas exchange (respiratory system) 

  • Flow of dissolved gases through medium (blood, hemolymph) to form circulatory system to transport dissolved gases to parts of body 

What is diffusion?

• Diffusion: movement of molecules from higher concentration to lower concen 

  • Gas Molecule when present in high concen -> collide with each other through random motion (bronian motion) -> collide and contain kinetic energy -> move farther from the point of origin 

What is the biggest issue with diffusion?

• Given a large enough surface→ diffusion is an extremely effective way to exchange gases and other substances over short distances between two compartments

• effective transport by diffusion is limited to short distances

• Diffusion limited by distance (inversely proportional) 

  • The farther gas molecules are apart -> less diffusion 

  • Optimum range: up to 100 micrometer 

    • Above: so far apart they won’t move without collisions that gave then KE to move farther -> no diffusion 

What is the difference between unicellular and multicellular diffusion?

• Unicellular 

  • Only have cell membrane (single bilipid layer, 1-2 microm) -> diffusion allows unicellular to exchange gases 

• Multicellular 

  • Diffusion requires interface where gas exchange takes places to be less than 100 mm 

How does diffusion occur in air?

• Air and water are different  

  • Oxygen in air: partial pressure of gas 

    • In atmosphere -> different gases as mixture 

      • Each gas exerts own pressure 

      • Multiply fraction of gas present in mixture with overall atmosphere pressure = partial pressure of gas 

How does diffusion occur in water?

• Oxygen present in water: dissolved in water = concentration of dissolved O2 

What is partial pressure?

• MmHg = unit for pressure 

• Tells how much gas is present in a location  

  • Important for rate of gas exchange 

    • Can increase or decrease from partial pressure of oxygen 

      • Valley = partial pressure is constant -> suddenly go on mountain -> change in altitude = decrease in fractional concen of O2 -> decrease in partial pressure -> body will sense change -> adjust rate of respiration -> start breathing heavily  

        • Few days = acclimatize by increasing red blood cell production  

• Partial pressure of N2 changed 

  • Dive deep in sea -> partial pressure of Nitrogen changes 

  • Atmosphere air has N -> but does not interact in gas exchange (only O2 and CO2) 

  • Deep in water -> N pp change -> bubble out from blood -> fatal 

    • Divers with pressurized gas with O2 and N2 -> so Partial pressure of nitrogen does not change 

What is bulk flow?

• the physical movement of fluid over a given distance

•  circulatory system helps move dissolved oxygen into rest of body in bulk flow 

  • Bulk flow: allows the organism to move gas into various distant parts of body 

What do larger animals rely on?

• Larger, more complex animals transport O2 and CO2 over longer distances to cells within their body. → rely on bulk flow + diffusion

• Larger animals have respiratory system + circulatory system 

  • Developed because gas transport and exchange happens at designated organ system (respiratory system) 

Where does diffusion occur in larger organisms?

• Surfaces in the body where diffusion occurs like lungs and intestines, have high surface area to volume ratios.

• Lung: interface to exchange gas form air to lung tissue 

  • Gas exchange takes place form blood in lung and air -> dissolved oxygen in blood needs to go to the rest of the body part -> 

How does ventilation occur int he resp system?

• Ventilation occurs In resp system and circulation in circ system -> reaches to deeper tissues 

  • Both steps imp 

  • Both steps are followed by diffusion 

    • Ventilation in lungs -> bulk lungs exchanged in lungs -> diffusion of Oxygen in lung alloviles  

    • After circulation after dissolved oxygen reaches tissues -> dissolved O2 form blood vessel goes to tissue through diffusion 

• Interface in lung: air and lung blood capillary  

  • In tissue: interface is blood and tissue interface 

What occurs in the intenstine?

• Diffusion also occurs In intestine 

  • Nutrients absorbed and secretion of chemicals and transport of secreted of molecules (hormones and factors) via diffusion 

How do aquatic animals use gas exchange?

• All animals obtain O2 from the surrounding air or water

• take in O2 from water breathe through gills: highly folded, delicate structures that facilitate gas exchange with the surrounding water

• Frogs 

  • Respire by skin 

How do poriferans exchange gas?

• Poriferans 

  • Thin epithelial layer -> respire through single layer of epithelial layer 

  • Less than 100 mm -> gas exchange can happen in single epi layer -> efficient gas exchange 

What are the structure of gills?

• Highly folded membranes 

• Gill filaments richly supplied with capillaries  

• Arranged in parallel layered form 

  • Arranged as same direction as water flow, opposite, or perpendicular from water flow 

  • Arrangement of lamella allows rapid exchange of gases 

• Lamellae are very thin (1-2 microm) -> allows diffusion quickly  

What are the types of gills?

• Two types of gills 

• External gills 

  • Tube warm + salamander  

  • More chance of gills being dmged + very delicate -> strong water current msut dmg it 

• Fishes developed internal gills protected by external flap (operculum)  

What is the structure of internal gills in fish?

• Fish need sufficient O2 to meet the energy demands of swimming.

• Fish actively pump water through their mouth and over the gills

  • gills located in a chamber behind the mouth cavity

What is the direction of flow for gills?

• Fish greatly reduce the energy cost of moving in dense, viscous water by maintaining a continuous, unidirectional flow of water past their gills

• Arrangement of gill filament is opposite of water (counter current flow) + Counter flow in lamellae of gill → help exchange gases better 

What is the operculum?

• In bony fishes

• protective flap overlying the gills → called the operculum

  • expands laterally to draw water over the gills while the mouth is refilling before its next pumping cycle

• Poriferans have operculum: bigger opening  

What do gills consist of?

• consist of a series of gill arches located on either side of the animal behind the mouth cavity and, in bony fishes, beneath the operculum.

• Each gill consist of

  • Gill filaments that contain numerous lamellae with capillaries network moves in a direction opposite to the flow of water past the gill

What are gill filaments?

• Each gill arch consists of two stacked rows of flat, leafshaped structures called gill filaments that contain numerous lamellae

What are lamellae?

• thin, sheetlike structures

• Have capillaries network that moves in a direction opposite to the flow of water past the gill

What is countercurrent flow?

• The type of organization in which fluids with different properties move in opposite directions

• Flow in two tubes opposite  

• At both ends -> same temp of fluid (both tube has cold and hot at end) 

• Exchange is efficient -> allows end to separate 

How does countercurrent exchange work in diffusion?

• At the same time as countercurrent exchange: CO2 readily diffuses out of the blood vessels and into the water that leaves the gill chamber.

• As a result of countercurrent exchange → fish gills can extract nearly all the O2 in the water that passes over them.

• A set of blood vessels carries the O2 -rich blood away from the gills to supply the fish’s body

• Fish gills 

  • Blood flows in lamellae -> moves low concentration of Oxygen to higher concen of O2

  • Water flows over in opposite direction (high oxygen concen -> passes through gills -> becomes low O2 

    • exchange of O2 -> allows to maintain region of low and high O2 concen 

      • Separates oxygenated blood from deoxygenated blood 

  • A set of blood vessels carries the O2 -rich blood away from the gills to supply the fish’s body

What is concurrent exchange?

• less efficient than countercurrent exchange

  • a steep concentration gradient is not maintained along the length of both tubes.

  • Instead, both tubes will reach an average temperature.

• Concurrent 

  • Keep close together -> transfer of heat energy due to flow of hot and cold water in tubes 

  • As flow continuous -> some time -> heat exchange at both of end of tube -> water is the avg temp btwn two 

    • Ends the energy merges -> avg of two physical factors 

What is the system that terrestrial insects evolved for gas exchange?

• Lower animals in invertebrates 

  • Use tubes (trachea) 

• Trachea: a system of air tubes that branch from openings along their abdominal surface into smaller airways

What do many terrestrial animals use for gas exchange?

• Many terrestrial animals, such as reptiles, birds, and mammals, have internal lungs for gas exchange.

• The respiratory surfaces of more complex and active animals are highly folded → creating a large surface area within a small space

• These surfaces are only one or two cell layers thick —> providing a diffusion distance of as little as 1 to 2 μm.

What is the structure of the lung system?

• Vertebrates: lung system 

• Starts with trachea -> divides into bronchi -> bronchiole -> alveoli sac 

  • Separate into alveoli (single layer structure that allows interface for gas exchange) 

    • Contain air breathed in  

    • Single layer epithelial layer is where gas exchange takes place 

What are the steps to insect breathing?

• Because of their small size → insects do not have a respiratory surface → instead employ a direct pathway of air transport that gets air directly to their tissues.

• breath through trachea

• insects rely on a two-step process of ventilation and diffusion to supply their cells with O2 and eliminate CO2 .

How does insect breathing work?

• Air enters an insect through openings (spiracles) along either side of its abdomen

  • spiracles can be opened or closed to limit water loss and regulate O2 delivery

• Diffusion occurs at the cell:

  • O2 supplied by the fine airways diffuses into the cells

  • CO2 diffuses out and is eliminated through the insect’s tracheae

• mitochondria of the flight muscles and other metabolically active tissues are located within a few micrometers of tracheole airways.

• Because O2 and CO2 diffuse rapidly in air, the tracheal system delivers O2 at high rates.

• Ventilation:  

  • Once airs enter trachea (enters in opening  of skins (spiracles)) 

    • Spiracles allow entry of air into trachea 

  • Trachea branch out to multiple tracheole -> reach other tissues and muscles 

  • At the muscle and junction of tracheole -> help of diffusion -> gas exchange -> 

  • After CO2 comes out of trachea  

What kind of ventilation do vertebrates use?

• most land vertebrates inflate and deflate to move fresh air with O2 into the lungs and expire stale air with CO2 out of the lungs

• Use Tidal ventilation

What is tidal ventilation?

• The low density and viscosity of air enables these animals to breathe by tidal ventilation

• Tidal ventilation allows movement of low density to enter body -> gas exchange takes place 

  • Requires less muscular energy  

• Air is drawn into the lungs during inhalation and moved out during exhalation

What is inhalation?

• Mammals and reptiles expand their thoracic cavity to draw air into their lungs.

  • The expansion of the lungs causes the air pressure inside the lungs to become lower than the air pressure outside the lungs.

  • The resulting negative pressure draws air into the lungs.

• Inhalation is active that requires contraction of diaphragm 

How is inhilation active?

What is exhilation?

• exhalation is passively driven by the elastic recoil of tissues that were previously stretched during inhalation.

  • The contraction of the lungs causes the air pressure inside the lungs to become higher than the air pressure outside the lungs.

  • The resulting positive pressure forces air out of the lungs.

• Exhalation is passive because lungs is elastic property from elastic tissue -> inhalation in complete lungs recoil back and exhale air with CO2 

How is inhalation and exhalation related?

• Lungs expand –> initiation of inhalation is triggered by contraction of diaphragm 

  • Diaphragm = largest muscle in human body 

  • When it contracts -> pulls the thoracic cavity and expand it -> creates negative pressure in the lungs 

    • Pressure from high pressure moves to low concentration 

  • Air from inhalation moves into the lungs -> alveoli where gas exchange take place 

  • When lungs filled with air -> pressure changes -> exhale the air needed (contains CO2 -> exhalation) 

What is the diaphragm?

• a domed sheet of muscle located at the base of the lungs that separates the thoracic and abdominal cavities.

What happens during relaxed breathing?

• In mammals, inhalation during normal, relaxed breathing is driven by contraction of the diaphragm

• At rest 

  • Diaphragm allows breathing (mostly using diaphragm) 

  • Exhalation occurs passively by the elastic recoil of the lungs and chest wall

What are intercostal muscles?

• attached to adjacent pairs of ribs

• assist the diaphragm by elevating the ribs on inhalation and depressing the ribs during exhalation

• used for active excersize

What happens to breathing during excersize?

• During exercise, other muscles assist with inhalation and exhalation.

• Intercostal muscles assist the diaphragm by elevating the ribs on inhalation and depressing the ribs during exhalation

  • Lungs require support of intercostal muscles present btwn ribs 

    • Intercostal muscles contract -> lift rib cage up -> expand thoracic cavity farther 

    • Contraction of diaphragm allows expansion of thoracic cavity  

    • When speaking or excersing needs better exchange -> intercostal muscle expands thoracic cavity 

• action of the intercostal muscles helps to produce larger changes in the volume of the thoracic cavity →

  • increasing the negative pressure that draws air into the lungs during inhalation

  • + assisting elastic recoil of the lungs and chest wall to pump air out of the lungs during exhalation

• Intercostal muscle and diaphragm work together 

What is the functional capacity of lungs?

• When inhale or exhale air -> certain volume of air that can exhale or inhale that can be recycled 

• Functional capacity of lungs (how much it can inhale and exhale, how much of air is always present in the lungs)  

  • Some air stays in alveoli -> lungs never collapse = residual air 

  • Portion of residual air is recycled with each breath (mixture of previous residual air and new one) 

What is tidal volume?

• Tidal volume 

  • At rest: amnt of air you inhale and exhale = .5 liter every cycle

    • Each breath inhale .5 liter of air and exhale .5 liter of air = tidal volume 

What is the ventilation rate?

• With a breathing frequency of 12 breaths per minute

• (breathing frequency × tidal volume) is 6 liters per minute.

• Ventilation rate can be changed by either increasing breathing frequency, tidal volume, or both.

What is the total lung capacity?

• Maximum volume of air = around 5600 mL 

• Maximum air exhale by forceful exhalation by  800 mL 

• Both maximum inhil and exhal = total lung capacity  

• During diseases condition -> total lung capacity can change 

What is the whole system of respiration?

• Hair in nose prevents the entry of any particulate matter in air to enter resp system 

  • If large particular matter enters nose -> hair traps it -> sneeze to expel 

• Air moves back into nasal cavity 

  • Air inhaled moves in nasal cavity to humidify (tirbulates?) 

  • Air inhaled is brought to body temp for efficient gas exchange in lungs 

• Air humidified and temp brought closer to body temp in nasal cavity -> towards pharynx 

• Air moves deeper into the trachea: composed of elastic cartilage -> flexibility and prevents from collapsing 

  • Trachea lies interior to the food pipe or esophagus 

    • Trachea do not collapse because of presence of elastic cartilage rings 

• Air goes down from trachea -> trachea bifurcates into two primary bronchi   

• Primary bronchi divide into terminal bronchi 

  • Terminal is 1 millimeter 

• Separates more into alveoli (single epithelial layer air sacs surrounded by capillaries) 

  • Pulmonary capillary surrounds single alveoli (alveolus) 

  • Single epithelial layer (1-2micro) -> gas exchange 

    • Oxygen form air diffuse form alveolus into pulmonary capillaries and Co2 diffuse out of pulmonary cavity into alveolus -> CO2 is exhaled  

What is the Larynx?

• Pharynx allows for speech and control flow of air in the 

•  lower resp system= larynx (adams apple) 

  • Vocal chords: noises 

What is the trachea?

• Point of bifurcation is sensitive (sensory receptors that can initiate cough reflex) 

• Lined by pseudo stratified columnar ciliated epithelial cells 

  • Cilia pushes back any matter or pathogen trapped in air -> push towards esophagus to be digested and cleared out 

  • Smoking makes cilia dysfunctional 

What kind of respiration do birds have?

• Tidal ventilation has expansion and deflation of lungs 

• Birds not tidal ventilation because lungs are not flexible -> rigid and do not inflate or deflate 

What is the structure of bird lungs?

• Lung + air sacs 

  • anterior air sac 

  • Posterior air sac 

  • Both surrounded by flight muscles  

    • Contraction of flight muscles contract 

How does bird respiration work?

• Birds inhale air -> air first goes to posterior air sac -> Contraction of flight muscles contract -> compresses air sac -> pushes fresh air into lung 

• In lungs gas exchange takes place -> deoxygenated air goes into anterior air sac -> contraction of flight muscles -> compression of anterior pushes deoxygenated air out of body through trachea and mouth 

How is blood circulated in birds?

• Birds: blood capillaries are perpendicular to the alveoli sac -> crosscurrent flow 

  • Allows gas exchange and efficient 

    • Lungs always received fully oxygenated blood 

    • Perpendicular exchange allows efficient exchange of gases 

• Bird lung always have oxygenated air 

  • Residual volume in human lungs, not always fully oxygenated air 

What controls respiration?

• Animals adjust their respiratory rate to meet their cells’ changing demand for O2 .

• unique: by both the voluntary and involuntary components of the nervous system

What does homeostasis depend on for breathing?

• often depends on sensors that monitor the levels of the chemical being regulated

• sensors = chemoreceptors

What are chemoreceptors?

• located within the brainstem

• in sensory structures called the carotid and aortic bodies.

• sense CO2 and H+ concentrations

Bifurcation definition?

• the division of something into two branches or parts.

What are carotid bodies?

• sense O2 and proton (H+ ) concentrations of the blood going to the brain.

• At bifurcation of common carotid are carotid bodies 

• Carotid and aortic monitor the oxygen and acid level of the blood going to the brain 

What are aortic bodies?

• monitor their levels in blood moving to the body.

• in the aorta

What is the aorta?

• Aorta: largest blood vessels that comes out from heart 

  • Supplies oxygenated blood to whole body  

• When blood goes out of level -> Aorta body and branch of Aorta goes towards neck (common carotid artery) 

What happens when concentration of CO2 in blood is too high?

• chemoreceptors in the brainstem stimulate motor neurons → activate the respiratory muscles to contract more strongly or more frequently.

• Stronger or faster breathing rids the blood of excess CO2 and increases the supply of O2 to the body.

What parts of the brain are used for respiration?

• Brain: pons and medulla 

What is the medulla?

• regulates essential, involuntary life-sustaining functions, including breathing, heart rate, blood pressure, and digestion

What are pons?

• Pons: resp center that controls the transition of inhalation controls the transition of inhalation to exhalation  

  • Controls the rate of respiration and in the brain stem  

What is the brain stem?

• Brain stem chemo receptors  

• Chemo receptors sense the concentration of CO2 and acidity in the brain 

How does chemoreceptors, carotid, and aortic work together?

• Chemoreceptors carotid and aortic check level of O2, CO2, and acidity 

  • During aerobic resp use lots of oxygen -> end product can create accumulation of acid (lactic acid) 

  • Exercise lactic acid produced -> change of pH of blood detected by chemoreceptors and ceratoid bodies 

  • If concen of CO2 is too high -> resp center in pons to increase rate of resp and to clear out the excess CO2 by exhalation  

    • Hyperventilation to increase removal of CO2 and inhalation of O2 

    • Negative feedback that increase rate of resp 

What is mammalian blood made of?

• composed of plasma, white blood cells, platelets, and red blood cells.

What is hematocrit?

• fraction of total blood volume that is red blood cells

Fish vs human hematocrit levels?

• A human has a hematocrit of 45%

• whereas a fish has a hematocrit of 30%.

  • Less hematocrit

  • Higher plasma fraction

• Mammal and fish blood 

  • Plasma 

  • 1% white blood cells and platelets 

  • Red blood cells 

  • Fraction of redblood cells = hematocrit 

What is blood plasma?

• Blood plasma is the fluid portion of blood without the cells.

• Plasma not used for transfusion because it has low oxygen carrying capacity  

What happens with low hematocrit levels?

• Blood with a lower hematocrit flows with less resistance but carries less oxygen.

• It can hold only as much O2 or CO2 as can be dissolved in solution.

What determines how much O2 can dissolve in solution?

• a measure of its solubility.

• CO2 is 30% highly soluble in solution compared to O2 

  • In blood, less soluble oxygen compared to CO2 

    • CO2 is 30x times more soluble than oxygen  → only about 0.2 ml of O2 can be carried in 100 ml of blood.

Why do mammals have less plasma?

• Dissolved concen of oxygen is low compared to CO2 -> compensated by the presence of higher hemocrit in mammals 

  • Red blood cells have hemoglobin 

    • Hemoglobin binds to oxygen molecule  

      • High carrying capacity -> more mole of oxygen are carried and stored by red blood cells than plasma 

Why do fish have more plasma?

• Fishes have more plasma because they use dissolved O2 in water (less O2 in water than air)

• Fish have lower metabolic rates, meaning they require less oxygen transport via red blood cells, allowing them to function with a higher proportion of low-viscosity plasma.

• When dissolved in water -> pp of O2 is low  

  • Rely more on oxygen dissolved in plasma = higher plasma concen ->  Higher plasma volume + dissolved O₂ helps compensate for the lower oxygen availability in water (and lower hemocrit) → still provide efficient gas exchange capacity

What is hemoglobin?

• hemoglobin evolved as a specialized ironcontaining, or heme, molecule for O2 transport

• the cells and the blood their red appearance

• Has two subunits

  • A subunit: made of proteins

  • B subunit: main oxygen-carrying protein in adult human red blood cells

  • + Heme group

What is a heme group?

• contains an iron atom,

• reversibly binds one O 2 molecule

• Given time point 1 mol of heme bind to 4 O2 

What does hemoglobin do in blood?

• By binding O2 and removing it from solution, hemoglobin increases the amount of O2 in the blood a hundredfold.

• After O2 diffuses into the blood, it diffuses into the red blood cells and binds to the heme groups in hemoglobin.

• Hemoglobin’s binding of O2 removes O2 from solution → keeping the pO2 of the red blood cells below that of the blood plasma so that O2 continues to diffuse into the cell.

• removal of O2 from the plasma → keeps the pO2 of the plasma below that of the lung alveolus → O2 continues to diffuse from the lungs into the blood.

• Because of its greater solubility → CO2 is transported in solution within the blood

What happens to most CO2 in the body?

• Most of the CO2 (about 95%) in the blood is converted to carbonic acid → dissociates to form bicarbonate ions (HCO3– ) and protons.

What is myoglobin?

• a monomer that contains only a single heme group

• a specialized O2 carrier within the cells of vertebrate muscles.

What happens in myoglobin?

• Myoglobin protein that is present in skeletal muscles 

  • Slow twitch fibers have more myoglobin 

• Myoglobin 

  • Only one heme -> only one oxygen can bind 

  • Affinity to bind with Oxygen is higher 

What happens in hemoglobin?

• 4 Heme groups → higher carrying capacity for oxygen

What happens during excerize?

• Hemoglobin that dissociates from oxygen and provides oxygen to tissue  

• Once oxygen is replenished -> usage of oxygen in tissue level creates low partial pressure -> allows myoglobin to release at low pp 

• When exercising, using oxygen bound to hemoglobin followed by myoglobin 

  • Why slow twitch fibers can go for longer 

What does the dissociation curve of hemoglobin look like?

• Sigmoidal due to the cooperative binding of oxygen by hemoglobin

  • Begins with slowly -> follows exponential phase -> platues out at 100% near saturation 

• Graph

  • Begins with slowly -> follows exponential phase -> platues out at 100% near saturation 

  • Hemoglobin has four heme that combines to 4 oxygen atom  

    • When first atom binds to first heme -> brings conformational changes in heme -> changes its affinity and increases the affinity of the next heme to bind more rapidly to the next oxygen 

    • Next oxygen binds quickly -> cycle repeats 

  • Confirmational changes allows for oxygen to bind with higher affinity = incorporated binding 

  • Region during early phase is the undergoing of corporates binding 

    • As soon as first O2 bind with first hemo -> picks up pace -> all four heme occupied by O2 -> saturates 

  • P50 = out of the 4 heme, 2 are occupied by O2 

What does the curve of myoglobin look like?

• Only one heme -> no incorporative binding -> does not have a sigmoid curve -> able to bind more strongly to oxygen  

• Add very low oxygen pressure allows for release 

• At low pp of O2 -> myoglobin releases oxygen 

How does myoglobin and hemoglobin work together?

• at any pO2, myoglobin binds oxygen more readily than hemoglobin → hemoglobin delivers oxygen to myoglobin muscle tissues

What does fetal hemoglobin levels look like?

• Fetal hemo curve is shifted left compared to maternal hemo

  • allows fetus to take up O2 from mother’s circulation

• Fetal hemoglobin 

  • During digestion period -> placenta provides nutrients and oxygen to growing fetus 

  • Even through fetus and maternal circulation is close (placenta connects circulation -> closed network with mother) 

  • Pp is not favorable for rapid exchange  

    • To overcome during digestional period 

    • Fetal hemoglobin have higher affinity to oxygen (less than myoglobin but more than maternal hemoglobin) 

  • Fetal shifts towards left-> allows high affinity in response to unfavorable pp of oxygen 

How does decrease in pH effect hemoglobin?

• Decreased pH often result of increased cell activity

• Decrease in pH caused by metabolism -> affects disassociation of O2 

  • When pH = 7.4 (physiological pH of blood) 

  • PH more acidic 

    • Right shift of dissociate curve 

    • Allows hemoglobin to release more O2 to cells 

• Right shift in hemoglobins O2 disassociation curve → hemo releases more O2 to active cells

What is an open circulatory system?

• Invertebrates 

• Still have blood visceral organ and heart to pump blood 

• Visceral organs bathed in blood 

• Contraction of muscles around periphery help in pushing the oxygenated blood towards the heart -> pump the oxygenated blood though the aorta  

• Open circulatory system supported by tracheal resp system  

  • Trachiel tubes bathing the visceral organs and muscles -> tracheal systems allow the efficient gas exchange in the open circulatory system 

How does circulation work in the circulatory system?

• Blood flows through vessel with muscular thickenings (act as pump) → blood empties into open cavity to supply tissues with nutrients → returned tot he circulation

What is a closed circulatory system?

• Vertebrates 

• Segmentation requires better circulatory system for distribution of oxygen throughout segments 

• Ventral blood vessel and dorsal blood vessel 

  • have lateral hearts 

    • Ventral blood vessel and btwn dorsal are blood capillaries that allows blood exchange to occur form tissue to pulmonary circulation to tissue 

How does circulation occur in closed circulatory systems?

• Blood flows through connected blood vessels

  • pumped by muscular hearts

• Blood flows through vessels to supply tissues with nutrients

What is laminar flow?

• Blood vessels 

  • Blood that flows into blood vessels called laminar flow 

• Laminar flow 

  • Cylinder of pipe and water flowing through it 

    • Water flow through -> flows in concentric layer 

      • Inner most layer of pipe is the one that faces the least amnt of resistance to flow 

      • Inner most layer flows the fastest 

• Ex

  • Fish has streamline shape -> provides middle part to be the farther end 

    • Fluid flow in the concintric layer = laminar flow 

What is needed for blood to flow through pipes?

• pressure (P) is required to overcome the resistance (R) to flow.

What is the rate of blood flow?

• rate of blood flow is governed by P/R,

  • rate of blood flow increases with an increase in pressure

  • decreases with an increase in resistance.

What is the resistance to flow determined by?

• determined in part by the fluid’s stickiness (viscosity)

• and vessel’s length.

  • Longer vessels of a given size impose greater resistance.

• main factor: vessel’s radius (r).

What is resistance?

• proportional to 1/r^4

  • if a vessel’s radius is reduced by half, its resistance to flow increases 16 times

What are the kinds of vessels?

• Arteries

• veins

What are arteries?

• Artery carry oxygenated blood 

  • Two layers of elastic tissue -> withstand high blood pressure and be able to maintain structure 

    • Recoiling ability: high blood pressure expand -> return to normal and recoil to normal size 

What are veins?

• Veins carry deoxygenated blood 

  • Walls: collect deoxygenated blood from extremities of body and push it towards the heart 

  • Since veins are working against gravity -> require mechanism to prevent backflow of blood -> walls prevent back flow 

What is the structure of vessels?

• Both artery and veins divide to form smaller blood vessels 

  • Artery -> arteriole -> capillary bed 

  • Veins -> no elastic layer but have walls -> prevent the back flow blood -> divide into venule -> capillary bed 

• Capillary bed have arteriole and venule end 

Which parts have the largest surface area?

• Since capillaries are last branching part of arities and veins -> huge surface area 

  • Max in capillary and least in aorta and veins