Final Exam

What is the blood oxygen utilization coefficient?

% of arterial O2 released to systemic tissues

What are the chemical properties of hemoglobin?

- forms highly specific, noncovalent weak bonds with oxygen at defined binding sites -has other sites where it binds to other!allosteric ligands which affect O2 affinity -is a multi subunit protein with four subunits covalently bonded that can bind to one oxygen each -do not modify primary ligand (O2), but undergoes conformational change when bound to O2 -contains heme covalently bonded to globin protein - exhibits cooperativity at O2 binding site so affinity increases when already bound to o2

Mechanism for HAPE

- increased HPV increases pulmonary HTN which increases pulmonary capillary pressure and artery pressure -alveolar capillaries leak due to stress failure and overperfusion/stretching

Selective distribution in amphibian and nonavian reptiles?

-2 atria in heart, oxy blood in left atrium, deoxy in right atrium -single ventricle with no septum in amphibians but has criss cross of spongy myocardium, muscular ridge septum in reptiles -ventricle discharges into contractile conus arteriosus which discharges in to arteries -lumen of conus arteriosus in amphibians is incompletely divided by ridge of tissue -turtles, snakes and lizards have selective distribution of oxy and deoxy due to septum

What is circulation in Teleost fish?

-Closed circulatory system -heart-ventral aorta-gills-dorsal aorta-systemic circulation -gills in series with systemic tissues

What characterizes the circulatory system of lung fish?

-Different from other air breathing fish -blood from lungs kept separate from system blood returning to heart

Why is ADL important?

-Dives that remain below ADL are efficient, repetitive and adaptive because they increase the range -dives that are above the ADL are inefficient because they increase surface time for recovery and are less adaptable

How do animals tolerate severe hypoxemia?

-Increase arterial pO2 at start of dive so gas exchange continues until lung collapse, then pO2 of arteries reach low levels -increase venous pO2 to arterial levels at start of dive via shunting and continued gas exchange, then venous pO2 reaches low levels

How does temperature affect the Hb-O2 dissociation curve? What are the implications?

-O2 affinity decreases as temp increases -Exercising tissues increases temp and get O2 while lungs do not increase temp and thus affinity remains high so Hb can load.

Why is there such high resistance in the systemic circuit?

-Poiseuille equation tells us that vessels of tiny radius tend to make great contributions to vascular resistance. -total cross sectional area increases as blood enters terminal arteries and microcirculatory beds causing the blood to slow (this is due to short length of capillaries and necessity for slowing so gas exchange to occur)

What are differences between fish who use gills only vs fish who use air breathing organs?

-Teleost have series circulatory system while ABO fish have parallel circulatory system -Thought to ensure that heart has higher oxygenated blood and expand aerobic exercise capabilities

What factors determine physiological adaptations to high altitude?

-altitude reached -ascent rate -individual characteristics

What are some things that affect the Hb-O2 dissociation curve?

-decrease in pH -shit in temperature -organic modulators -inorganic ion modulators

What are the effects of high altitude?

-decreased PaO2 which leads to decreased CaO2 (hypoxemia) which leads to cellular hypoxia

Fish heart anatomy

-four chambers in series: sinus venosus (where great veins empty), atrium, ventricle (main source of force), and bulbous segment that empties into the ventral aorta -bulbous segment in lungfish and elasmobranchs is conus arteriosus and has cardiac muscle and contracts with ventricle -bulbous segment in teleost fish is bulbus arteriosus which has vascular smooth muscle and elastic chamber that is pressure reservoir

What kind of pressure circuit do mammals and birds have?

-high pressure -due to high resistance in capillaries

What are acute respiratory changes at high altitude

-hyperventilation -Hypoxic ventilatory response (HVR): if higher, fare better at altitude bc greater decrease in pCO2 and increase in pO2 in lungs which decreases hypoxemia

What are the acute cardiac function changes at high altitude?

-increase myocardial contractility -increased cardiac output (increase HR) but initially decreased stroke volume (from decreased left ventricular dimension and filling pressure due to diuresis or decreased plasma volume) -HR increases due to increased sympathetic activity which increases O2 delivery -systemic vasodilation: increases O2 delivery to tissues -coronary arteries dilate which increase myocardial blood flow compensating for low O2

Redistribution of cardiac output in amphibians and non avian reptiles

-intermittent breathers: during apnea CO to lungs is reduce, when breathing CO to lungs increased -mechanism is peripheral vascular resistance changes: CO increases to lungs when PVR low compared to PVR in systemic circulation

What is HAPE?

-leading cause of death -2-4 days after arrival -dyspnea on exertion, reduced exercise tolerance, dry unproductive cough -severe fatigue:tachycardia:tachypnea: productive cough (pink frothy, crackles), coma -risk factors: rapid ascent, lack of dieresis, previous HAPE, men, heavy exercise, pre existing lung disease, compromised cardio, cold

What are properties of respiratory pigments?

-metalloproteins -strongly colored some of the time -undergo reversible combination with molecular O2 -have many forms and are conserved, vary spatially and temporally within an organism

How does lungfish heart differ from other fish?

-partially divided into right and left atrium and ventricle -oxygenated and deoxygenated blood enter heart separately -blood from lungs enters left side of atrium, blood from systemic circulation enters right side of atrium -conus arteriosus has 2 ridges that create 2 channels -four pairs of afferent branchial arteries

Maintenance of different pressures in amphibians and nonavian reptiles

-pythons and varanid lizards: different BPs via separation of ventricle (high BP to systemic circulation, low BP to lungs so no ultrafiltration) -other reptiles have no mech to separate ventricle so maintain same low pressure with no ultrafiltration/fluid in lungs

Why do high altitude illnesses occur?

-rapid ascent: insufficient time for acclimatization

What are long term implications of hyperventilation at high altitude?

-reduces pCO2 which decreases H ions and raises pH resulting in respiratory alkalosis -shifts Hb-O2 dissociation curve to left

What characterizes the capillaries?

-site of gas exchange between blood and tissues -thin walls made of vascular endothelial cells that are fenestrated -most closed at rest, open during exercise -high in brain, skeletal muscle, myocardium -drain into venules

How is cardiac output in teleost fish?

-small hearts compared to size and decreased cardiac output because of low O2 demands from low MR -heart empties completely at end of systole -lower arterial pressures

What characterizes veins?

-take blood back to heart, increase in size -thin walls with low blood pressure -have one way valves that prevent back flow -skeletal muscles contract to help flow -have capacitative properties bc can distend to store blood

What characterizes arteries?

-thick walls -able to endure considerable pressure -made of smooth muscle, elastic and collagenous connective tissue

Crocodilian hearts

-ventricle completely separated -2 systemic aortas -have foramen of panizza where aortas connect just after leaving ventricles -perfect select distribution possible

What is acute mountain sickness

-when ascent outpaces acclimatization -common -risk factors: rapid ascent to high altitude, lack of diuresis, heavy exercise, compromised cardiovascular condition, respiratory tract infection -symptoms: headache from increased ICP, fatigue, dizziness, sleep disturbance, anorexia, nausea, vomiting

How do allosteric modulators affect the dissociation curve? Which one is prominent?

-work allosterically -organophosphate 2,3-DPG decreases affinity of O2 -helps people with anemia, will produce more so affinity is lower and can unload more in systemic tissues

What are acidosis and alkalosis?

1. Acidosis is when pH shifts to acid side of normal pH at a temp 2. Alkalosis is when pH shifts to the alkaline side of normal pH

What is the process of oxygen transport by Hb?

1. Deoxygenated blood (low pO2) meets air in the lungs 2. O2 diffuses from alveolar gas into the lungs, increasing pO2 3. As pO2 in the blood rises, hemoglobin takes up the amount of O2 as dictated by oxygen dissociation curve 4. As pO2 rises, Hb saturation rises. At normal alveolar pO2, Hb is nearly 100% saturated. 5. O2 travels in blood via Hb to the tissues. 6. The pO2 in the mitochondria is low due to conversion of O2 into H20. Thus O2 diffuses from blood to mitochondria. 7. This causes blood pO2 to fall, resulting in oxygen unloading by Hb. This makes Hb-O2 available to mitochondria.

What are the two types of Bohr effect?

1. Fixed acid bohr effect: pH and [H+] changes, [H+] combines with sites on Hb as allosteric modulator which increases O2 dissociation 2. CO2 bohr effect: CO2 binds chemically with Hb, affecting affinity and allosteric modulator

What are adaptations for respiratory pigments?

1. Hb brings O2 to Mb: Hb carries o2 from lungs where it has a high affinity. It goes to the tissues and transfer to Mb which has lower affinity so can transfer to tissue better 2. hypoxic environments: in low O2 env, evolve Hb with higher affinity, in high O2, Hb evolved with lower affinity, increase total Hb concentration 3. Allometry: decreased affinity with decreased size to counteract increased MR

How does circulatory system vary with exercise level in fish?

1. Inactive fish: small hearts, little compact myocardium, low CO 2. Active fish: large hearts, more compact myocardium, high CO

What are the kinds of flow in a tube?

1. Laminar flow: fluid in the middle has highest velocity, fluid by sides has nearly 0 velocity. 2. Turbulent flow

What are the two main challenges of fish circulatory system?

1. No heart between breathing organ circulation and systemic circulation so pressures heart provides must be enough to drive blood through both 2. oxygenation of myocardium depends fully or partly on O2 gained from the blood flowing through the lumen of the heart in fish and this blood is relatively deoxygenated because was just in systemic circuit

What are the 8 roles of respiratory pigments in animals?

1. O2 transport 2. O2 stores 3. Buffers of Blood pH 4. CO2 transport 5. Mb facilitated O2 diffusion and storage 6. catalysts for other reactions 7. sulfide transport 8. Regulation of mitochondrial respiration-Mb

What are the two forms of acidosis and alkalosis?

1. Respiratory: abnormal CO2 elimination by lungs: increased CO2 exhalation (alkalosis) or impaired CO2 exhalation (acidosis) 2. Metabolic: alter [bicarb] in blood : Loss of HCO3 in gastrointestinal fluids (acidosis)

Why is it disadvantageous to store air in lungs?

1. buoys 2. alveoli collapse from pressure so cant use 3. decompression sickness

How to avoid AMS?

1. gradual ascent 2. stop and descend if symptoms appear 3. sleep at lower altitude

How do animals maximize aerobic dive duration?

1. increase amount of O2 take with them: increased O2 stores 2. reduce O2 consumption during dives: dive response 3. Survive with low O2 levels: increased hypoexmia tolerance

What factors influence degree and rate of bradycardia?

1. method (forced, trained, or free dives) Lower in forced 2. duration and depth: longer and deeper decreases 3. diver type

What factors affect the rate of blood flow?

1. pressures at entry and end of vessel 2. radius of the lumen of the vessel 3. length of the vessel 4. viscosity of the liquid

What are the main determinants of PvO2?

1. rate of blood flow through the tissue: if decreases then pO2 decreases 2. arterial pO2: if increases then pO2 increases 3. Amount of hemoglobin/unit of blood volume if increases, then pO2 increases 4. Tissue rate of O2 consumption, if increases then pO2 decreases

Where are the O2 stores?

1. respiratory 2. blood (largest) : increase volume, oxygen carrying capacity, and oxygen saturation 3. muscle: increase Mb concentration, muscle mass, Mb O2 binding capacity

Deep, long duration divers characteristics and benefits

1. respiratory system: deplete O2 store by exhaling and collapsing lungs 2. cardiovascular: increase blood O2 store, dramatic bradycardia and blood flow changes 3. muscle: muscle O2 store increases and Mb-O2 store is depleted Benefits: maximize aerobic foraging (<ADL) and reduce chance of bends

Shallow, Short duration dive characteristics and benefits

1. respiratory: O2 store increases, inhale 2. Cardiovascular: blood O2 store decreases, moderate bradycardia 3. muscle: muscle O2 store increases, Mb-O2 depletion Benefits: respiratory store, less known about use of blood O2, ADL rarely measured

What are the three themes of circulation in amphibian non avian reptiles?

1. selective distribution: to what extent is oxygenated blood sent to the systemic tissues and deoxygenated blood to the lungs? 2. maintenance of different blood pressures in the systemic and pulmonary circuits: can high pressure be maintained in the systemic circuit to produce high flow rates in that circuit while low pressures are maintained in the pulmonary circuit to prevent flooding the airways with fluid 3. Redistribution of cardiac output: to what extent is flow to the lungs adjusted separately from that to the rest of the body?

What is the Bohr effect?

A decrease in pH or increase in pCO2 decreases affinity.

What is the Root effect?

A decrease in pH reduces O2 content in the blood by reducing amount of O2 that binds when saturated. Occurs in addition to Bohr effect, and leads to increase in pO2.

What are myoglobin?

A type of hemoglobin found in the muscle. Used for oxygen storage. A single unit molecule that makes tissue red.

How does affinity affect respiratory pigments? How does affinity affect the O2 dissociation curve?

Affinity determines how readily the ligand binds. When there is low affinity, high pO2 is needed to load and unload. The opposite is true for high affinity. Lowering the O2 affinity shifts the curve to the right, meaning that you need a higher pO2 to become more saturated. Increasing affinity shifts the curve to the left.

What is the equation for flow rate? What is vascular resistance?

Also called total peripheral vascular resistance. Resistance to blood flow offered by all of the systemic vasculature, except the pulmonary vasculature

What does mixed venous pO2 represent?

An average of the O2 partial pressures of blood leaving the various systemic tissues. It can thus be used to gauge the overall drop of pO2 during circulation through all tissues combined.

Characteristics of arterioles? What mediates vasomotor control?

Arterioles are structured like arteries. They have muscle and connective tissue and have vasomotor control which means they can vasodilate or vasoconstrict. Thus they control blood flow. This is mediated by nitric oxide, sympathetic NS, hormones.

What are the main issues diving mammals face?

Balancing foraging and migrating with oxygen limited environment and high pressure. Thus must manage hypoxia tolerance, reduced oxygen consumption, and pressure tolerance

How can drop in blood pressure between two places be used as a measure of the energy cost of blood flow?

Because its horizontal flow, the drop in pressure is a good index of the heat produced by overcoming opposing viscous forces

How is blood pressure analyzed? What assumptions need to be made?

Blood flow can be analyzed by pressure produced by heart as sole driving force. The assumptions made for this are assuming the kinetic energy of blood does not vary within the system and that the animal in question is horizontal so that potential energy is the same.

What is the starling landis hypothesis?

Blood plasma loses volume in the initial segments of the systemic blood capillaries but regains volume in the final segments. Overall effect is net loss. At arterial ends of capillaries, the hydrostatic pressure of the blood exceeds that of the tissue fluid but because of the hydrostatic pressure difference favoring efflux of fluid from capillaries is greater than osmotic pressure difference favoring influx, fluid is forced out of capillaries. However, as blood flows through capillaries, hydrostatic pressure falls. At venous ends, osmotic pressure difference favoring influx of fluid into capillaries exceeds the hydrostatic pressure difference favoring eflux, so net influx occurs.

What happens to CO2 when it dissolves in the blood? Does CO2 act as an acid or a base?

CO2 dissolves in the blood but only a small fraction of it is present because it forms carbonic acid which then forms H+ and bicarbonate. Thus CO2 acts as an acid because it produces H+.

How is HCO3 cleared?

CO2 enters blood, diffuses into RBC, CA converts it into HCO3 and H, Hb takes up H b/c deoxy. Transporter protein in RBC membrane diffuses HCO3 out and chloride in (chloride shift). HCO3 goes into plasma.

What are the adaptive consequences of the Bohr effect?

CO2 is higher and pH is lower in system tissues compared to lungs. Thus respiratory pigments decreases affinity when blood reaches systemic tissues, and increases affinity in breathing organs. Thus Hb holds onto O2 in lungs and lets go in tissues.

What is the Haldane effect?

CO2 transport depends on Hb oxygenation. DeoxyHb increases CO2 uptake in the blood. This is because it binds to H which drives HCO2 formation and increases CO2 in blood. Opposite is true for oxyHb. This promotes uptake in tissues of CO2 and unloading in lungs. Thus Hb plays role in CO2 and O2 transport.

How can you increase the number of RBCs?

Can increase RBC via erythropoesis in the bone marrow. It is under endocrine control, specifically a glycoproteins hormone called erythropoietin from the kidneys. This is unregulated by hypoxia and mediated by transcription factor HIF-1.

What is ultrafiltration?

Capillaries have blood inside them and interstitial fluid outside. Pressure inside exceeds pressure outside causing difference in hydrostatic pressure that favors pressure driven bulk flow of fluid out of blood plasma across capillary walls. Blood plasma has higher osmotic pressure than extracellular fluid thus favors osmosis of water into blood plasma across capillary walls.

How can you determine O2 yield to tissues?

Compare Hb saturation after leaving lungs to saturation after passing through systemic tissues (mixed venous blood).

What is the Fick equation?

Describes how blood flow is increased during exercise through changes in cardiac output and vascular resistance without increasing blood pressure. During exercise, vO2 increases by increasing cardiac output/ blow rate (stroke volume and HR) and increased O2 extraction. Also decrease vascular resistance through vasodilation at microcirculatory beds at muscles and increase number of open capillaries (decreases resistance, decreases diffusion distance to increase O2 delivery, and increase flow without increasing velocity (residence time).

What is the total CO2 concentration in the blood?

Dissolved CO2, HCO3 (most), carbonate groups (CO2+Hb/other proteins).

What happens to O2 transport during exercise?

During exercise, respiratory rate increases but pO2 decreases in the lungs because there is less time for diffusion. This is okay because only use 25% of blood O2 at rest. The rest is a venous reserve, which is depleted during exercise. This is helped because at rest, PvO2 is below the plateau on the curve. Thus, during exercises, if it decreases a bit, there is high yield of O2 in blood from steep part of the curve.

What is carbonic anhydrase? Where is it found?

Enzyme that catalyzes hydration of CO2 to form HCO3. It is essential to efficient CO2 tx. It is found in RBC and in endothelial walls of capillaries (essential and localized).

What are buffer pairs? When are they most effective? Where are they found?

HX -> H+ + X- X is a chemical group that combines reversibly with H. If add H, you shift reaction to the left; if remove, shift to the right. HX and X are the buffer pair and are most effective when 1/2 of X groups are free and half are bound to HX. Buffer groups can be found on Hb.

What is hemoglobin called when it has oxygen? When it doesn't?

Hemoglobin bound to oxygen=oxyhemoglobin Not bound to oxygen= deoxyhemoglobin

Where are hemoglobins found? What is a measure of this?

Hemoglobins are found in red blood cells. They are measured using hematocrit which indicates the percent of RBCs in blood.

What is the respiratory pigments found in vertebrates and what are its functions?

Hemoglobins have the following functions: -oxygen carrying -buffers, CO2 transport -found within muscle cells and nerves -serve as intracellular depots for oxygen

What is the aerobic dive limit? What is its mechanism?

How long an animal can dive without net accumulation of lactate above resting level. Caused by depletion of one of 3 O2 stores: respiratory, blood, or muscle

What happens to blood pressure in the middle of the vessels? What causes this?

In the middle of the vessels, the pressure of the blood becomes diminished. This is the result of laminar flow. This is caused by internal friction which depends on dimensions of tube and the viscosity of the liquid. This internal friction causes some of the kinetic energy of the blood being degraded into heat.

Poiseuille equation

Increasing difference in pressure between two ends of a tube increases the rate of flow through the tube. Raising the viscosity diminishes the rate of flow. Rate of flow is extraordinarily sensitive to changes in the radius of the lumen (fourth power).

What happens to fluid that is efluxed to extracellular tissue?

It is picked up by lymphatic system and returned to blood. If not, edema will occur.

What determines how much bicarbonate is formed from dissolved CO2?

It's not due to principles of solubility but rather the action of compounds that act as buffers of pH (blood buffers). Blood buffers remove H+ from solution which drives bicarbonate formation

Why is blood pressure able to be maintained as arteries branch and become smaller and thinner?

LaPlace's law T=r(change)P T-tension, r-radius of the lumen, (change)P-pressure difference between walls. Because of this if a small artery is exposed to the same blood pressure as a large one, the tension developed within its walls is lower than that developed within the walls of the large artery. Thus the walls of small arteries do not need to be fortified as those of large arteries to resist overexpansion. Applies to blood capillaries too.

Is pulmonary circuit high or low pressure? why?

Low so that no loss of fluid from pulmonary capillaries occurs. There is lower vascular resistance due to shorter path and lack of arterioles. Prevents ultrafiltration and keeps lungs "dry" aka no fluid in alveoli (pulmonary edema).

What is the dive response?

Mechanisms to reduce oxygen consumption 1. bradycardia: decrease HR/CO 2. peripheral vasoconstriction: redistribute blood flow to brain, myocardium and lungs, and muscle isolation

Is venous side high pressure and high resistance?

No, low on both. Most of the pressure produced by left ventricle has been degraded by heat by the time it reaches the veins.

In the heart, which side is oxygenated? Which side is deoxygenated? What are the two kinds of circuits?

Oxygenated is left Deoxygenated is right There is a pulmonary and a systemic circuit

Flow of energy through the blood vessel

Pressure at entry end of blood vessel is potential energy that is converted to kinetic energy through the motion of the blood. Then, the pressure is converted to heat as it passes through the tube.

What happens during high intensity exercise to venous O2 pressure?

PvO2 is stable during most exercise states because the rate of blood flow to muscle changes, increasing as oxygen demand increases. During high intensity exercises, PvO2 decreases because can't increase blood flow exponentially, so at 100% utilization and pO2 in muscle approximates zero. pO2 of mixed venous blood stays well above O. If reach critical PvO2, then aerobic catabolism is impaired.

How is the Bohr effect limited?

Removal of oxygen from Hb will force reaction to the left, causing HB to load H+.The diffusion of O2 out of blood causes pigments to unload O2 and bind to H+, removing it from the blood. This limits the increase in H+ and decrease in pH. HbO2 + H + ↔ HbH+ + O2

Where is root effect seen especially?

Teleost fish. Helps inflate swim bladder and improve fx of eyes.

What is the effect of the elasticity of arteries?

The energy of each heart contraction is stored as elastic potential energy in the artery walls. This helps maintain pressure in between contractions. Thus the two main effects are 1. pressure damping effect: variations in arterial pressure over the cardiac cycle are reduced 2. pressure reservoir effect: pressure maintained between beats

What determines how many of Hb binding sites are occupied by oxygen? How is this represented graphically?

The fraction of O2 binding sites that are oxygenated varies in a graded manner with O2 partial pressure. This is represented by the oxygen dissociation curve. This can be either % saturation or blood O2 concentration versus O2 partial pressure.

What is the hill coefficient? What is myoglobin's coefficient?

The hill coefficient expresses the extent of cooperativity. n=1 for no cooperativity but can get as high as 6. Myoglobin has n=1 bc one 1 subunit.

What is P50? How does it relate to affinity?

The partial pressure of oxygen at which pigment is 50% saturated. It is inversely related to affinity.

What determines the shape of the Hb curve?

The shape of the O2 dissociate curve depends on O2 binding site cooperativity. The curve for Hb is sigmoidal because of the cooperativity of the 4 binding sites. There is a steep relation between O2 binding and pO2 in the mid range of pO2 values.

What is the CO2 dissociation curve? What determines its shape?

The total concentration of CO2 in blood vs pCO2. Shape depends on HCO3 formation, thus it depends on buffers.

What adaptations do icefish have?

They do not have Hb in blood. Low temp of env increases solubility of O2 in water and blood. Large heart, high blood flow rate, large blood vessels in the tissues.

What do respiratory pigments do and why is it necessary?

They increase the amount of oxygen that can be carried per unit blood, which increases the carrying capacity of the blood. This counteracts the low solubility of oxygen in aqueous solutions and allows the heart to work less fast and intensely.

What lines the entire circulatory system? What are the roles of these cells?

Vascular endothelium, a single layer of epithelium. These cells secrete agents like nitric oxide, synthesize and degrade hormones, and participate in the immune response.

What features permit highly sensitive temporal and spatial control of blood distribution?

Vasomotor control allows change of radius of vessel so can affect blood flow profoundly. Independently controlled microcirculatory beds, with AV anastomosis controlled by arteriole. This is primarily local, not systemic.

How does blood flow through blood vessels? What is an anastomosing network?

arteries-arterioles-capillaries-venule. Capillaries combine arterioles with venules. Arterioles determine rate of flow into bed (thus these are independently controlled).

Muscle O2 studies

in forced, blood flow decreases soon and O2 depletion occurs sooner

What is Hypoxic pulmonary vasoconstriction (HPV)?

redistributes pulmonary capillary blood flow to areas of high O2 availability -increase pulmonary vascular resistance -increases pulmonary arterial pressure, can lead to HTN -opposite of systemic vessels -optimizes blood gas exchange -ventilation perfusion matching