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140 Cards in this Set
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Respiration |
All the processes of gas movement, two distinct components, oxygen consumption or external respiration and cellular respiration or internal respiration |
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Aerobic |
Animal requires molecular oxygen for oxidation of energy substrates, require uptake of oxygen + transport to sites of utilization, reciprocal transport of carbon dioxide, diffusion is a slow but important process, the problem of size is due to uptake area and diffusion distance |
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Theoretical size limit for diffusion exchsnge |
1 mm diameter, shape is very important due to some animals relying strictly on diffusional gas exchange such as protozoan which are small single felled, sponges and cnidarians which rely solely on diffusion, some worms, larval stages of some invertebrates and even some chordates and vertebrates |
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Gas exchange |
4 linked processes in multicellular animals, oxygen is transferred through convection (bulk transport) through an ambient medium such as air or water, then it is diffused through a gas exchanger such as lungs or fills, then through convection it goes through ECF (blood) circulation, ultimately it ends up diffusing into the tissues (mitochondria) |
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Steps in external ventilation |
Four of them: ventilation (bulk transport of external media across a gas exchange surface), respiratory exchange (gas diffusion between the environmental medium and internal body fluids), circulation of extra cellular fluid (bulk transport of the ecf (blood or hemolymph), cellular exchange (gas diffusion between the cells immediate surroundings and its mitochondria) |
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Oxygen demand increases with size |
Which in turn can increase metabolic rate, activity and even temperature |
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Solubility of oxygen |
Inversely related to temperature and salinity, therefore higher temperature increases metabolic rate which decreases the solubility of oxygen, also seawater has less ml of oxygen per liter than freshwater at any temperature |
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Solubility and diffusion |
Oxygen availability becomes limiting before problems related to diffusion gradient for carbon dioxide, diffusion coefficient (D) is inversely proportional to the solubility/ sq rt of the mw. Meaning carbon dioxide is a larger molecule but it diffuses faster due to a size increase changing diffusion coefficient |
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I'm aquatic organisms |
Availability of oxygen is a problem in aquatic organisms compared to build up of carbon dioxide |
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Problem of gas exchange are different |
Water is a more difficult medium than air for gas exchange due to air having constant oxygen levels, bimodal breathers such as the lungfish can breath air or water (it is actually an obligate air breather, needs both) |
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Air vs water |
Oxygen content(ml/L) and diffusion of oxygen(cm^2/s) is higher in air, but density(kg/L) and viscosity (cP) is higher in water |
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Solubility limits oxygen in water |
Solubility is the saturated concentration under specified conditions which depends on nature of gas and medium, temperature and other solutes present |
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Unassisted membrane transport |
Diffusion - which are random collisions and intermingling of molecules as a result of their continuous, thermally induced random motion, the net movement of molecules from an area of higher concentration to an area of lower concentration, equilibrium is reached when there is no concentration gradient and no net diffusion |
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Permeability |
If a substance can permeate the membrane then diffusion occurs if it can't then no diffusion occurs |
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Permeability |
If a substance can permeate the membrane then diffusion occurs if it can't then no diffusion occurs |
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Ficks law of diffusion, dependence |
The rate at which diffusion occurs depends on concentration gradient, permeability, surface area, molecular weight, distance, temperature |
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Permeability |
If a substance can permeate the membrane then diffusion occurs if it can't then no diffusion occurs |
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Ficks law of diffusion, dependence |
The rate at which diffusion occurs depends on concentration gradient, permeability, surface area, molecular weight, distance, temperature |
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Ficks law of diffusion, dependence outcome |
Higher concentration gradient of substance (delta c), higher surface area of membrane (A) and higher lipid solubility (beta) all equate to a higher rate of net diffusion, higher molecular weight of a substance (MW) and longer distance (thickness) (delta X) equate to a lower rate of diffusion |
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Modified fick equation |
Q is inversely proportional to delta C times A times P |
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Gas diffusion follows Ficks law |
For gases, concentration gradient is replaced by partial pressure gradient, the partial pressure of a gas is the pressure exerted independently by the gas within a mixture of gases, so if Po2 in dry atmospheric is 21% o2 then .21 * 760 mmHg = 160 mmHg at standard temperature, water that is in equilibrium with air has the same gas partial pressure as the air but the concentration may be different depending on the solubility of the gas such as oxygen vs carbon dioxide |
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Gas parties pressures in atmospheric skr |
Total is 760 mmHg, Nitrogen gas is 79% or 600 mmHg, oxygen is 21% or 160 mmHg |
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Gas pressure units |
mmHg is in Torr 1 atm = 760 mmHg Si unit of kPa therefore 1 torr = 0.1333 kPa 1 atm = 101.3 kPa |
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Concentration and fractional concentration |
Concentration (c) is the quantity of gas/total containing volume such as 210 ml/L Fractional concentration of dry gas (F) is a decimal fraction such as F(o2) * V(air) = V(o2) .21 * 1000 = 210 ml/L = V(o2) But actual oxygen in air is .2095
The same units can be used for medium (air or water) and for blood, we must specify conditions because volumes vary with temperature and pressure STPD = standard conditions (0 Celsius, 1 atm, dry) standard temperature, pressure and dry |
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Breathing can be tidal or flow through |
Tidal breathing is breathing by an external medium being moved in and out of the same opening through inhalation and exhalation, fresh medium is only brought in half the time and is mixed with depleted medium
Flow through breathing is when the external medium enters one opening and leaves through a separate opening, the flow of fresh medium can be continuous and very little mixing occurs, this results in a more efficient gas exchange than tidal breathing, this is important due to lower oxygen in salt water |
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Water is a more difficult medium than air for gas exchange |
Due to higher viscosity, 02 being less soluble in water, rate of diffusion of gases is slower, solubility of oxygen decreases with increasing salinity and temperature, also the oxygen content in water is more variable due to habitat variation, environmental water contains many more components than air such as trace elements, minerals and organic matter |
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There is a diversity in gas exchangers |
The Maine routes are the integument and fills, but we also have the mouth, pharyngeal air sacs, swim bladder (lung), cloaca, gut and operculum (gill cover) |
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Integumentary respiration |
Is through the skin (cutaneous), this is common in flatworms and Cnidaria, it is enhanced by internal circulation, it is very important in amphibians, aquatic reptiles and most fishes, this is because during hibernation frogs and turtles exchange all of their respiratory gases across the skin, eels exchange 60% of hades through highly vascular skin |
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Cutaneous gas exchange in fish |
The thick integument (263 micrometer or so) of some fish is sufficient for gas exchange but not optimal, compared to .5 of lungs, this is possible due to superficial capillaries in epidermis being very close to the surface (7 micro), once gas is in capillaries then bulk transport takes over |
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Capillary Recruitment |
Capillaries can be recruited or derecruited to change the effective area which is the area where gas can be diffused |
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Capillary Recruitment |
Capillaries can be recruited or derecruited to change the effective area which is the area where gas can be diffused, capillaries in amphibians are dense with 30-200 capillary meshes/mm^2 |
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Capillary Recruitment |
Capillaries can be recruited or derecruited to change the effective area which is the area where gas can be diffused, capillaries in amphibians are dense with 30-200 capillary meshes/mm^2 |
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3 processes determine oxygen uptake across skin |
Diffusion, bulk transport (= convection) in medium (maintains oxygen pressure gradient), perfusion (volume rate of blood flow to a capillary bed), any or all processes may be limiting in different situations |
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Boundary layer |
The boundary layer is right above the skin, which Is due to slow water surrounding the skin from deprivation of oxygen, need faster currents or waddling of water to keep oxygen flowing, this is due to friction over the skin, the boundary is ultimately inversely proportional to 1/sq rt of the velocity |
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Integument of all water breathers |
Permeable to gases except for calcified structures, it has multiple functions (thinning is not always possible, thicker skin suffices for gas exchange if is vascular |
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Integument of all water breathers |
Permeable to gases except for calcified structures, it has multiple functions (thinning is not always possible, thicker skin suffices for gas exchange if is vascular |
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Bimodal breathers |
The South American swamp eel can live in areas with little oxygen because they can use air, they can take a gulp of water or air |
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Integument of all water breathers |
Permeable to gases except for calcified structures, it has multiple functions (thinning is not always possible, thicker skin suffices for gas exchange if is vascular |
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Bimodal breathers |
The South American swamp eel can live in areas with little oxygen because they can use air, they can take a gulp of water or air |
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Gut breathing |
Some catfish use gut for gas exchange (respiratory intestine), the water goes into the intestines and vessels in lining of intestines |
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Integument of all water breathers |
Permeable to gases except for calcified structures, it has multiple functions (thinning is not always possible, thicker skin suffices for gas exchange if is vascular |
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Bimodal breathers |
The South American swamp eel can live in areas with little oxygen because they can use air, they can take a gulp of water or air |
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Gut breathing |
Some catfish use gut for gas exchange (respiratory intestine), the water goes into the intestines and vessels in lining of intestines |
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Cloacal Respiration |
Some turtles have it, there is a muscular cloacal orifice where water enters the system, paired cloacal bursar expand and contract via the muscles of the inguinal pocket, long fimbriae lining the inner surface of the bursae are highly vascular and efficiently extract oxygen from the water, this mode allows the turtle to seldom need to come up for air, the water is pumped in and out of pouches known as cloacal bursae via the muscles of the inguinal pocket at a rate of 15 to 60 times per minute |
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Integument of all water breathers |
Permeable to gases except for calcified structures, it has multiple functions (thinning is not always possible, thicker skin suffices for gas exchange if is vascular |
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Bimodal breathers |
The South American swamp eel can live in areas with little oxygen because they can use air, they can take a gulp of water or air |
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Gut breathing |
Some catfish use gut for gas exchange (respiratory intestine), the water goes into the intestines and vessels in lining of intestines |
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Cloacal Respiration |
Some turtles have it, there is a muscular cloacal orifice where water enters the system, paired cloacal bursar expand and contract via the muscles of the inguinal pocket, long fimbriae lining the inner surface of the bursae are highly vascular and efficiently extract oxygen from the water, this mode allows the turtle to seldom need to come up for air, the water is pumped in and out of pouches known as cloacal bursae via the muscles of the inguinal pocket at a rate of 15 to 60 times per minute |
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Plasticity of skin surface area and thickness |
In 1941, Krogh demonstrated phenotypic plasticity (raised tadpoles in different O2 levels) of amphibian fills: hypoxia led to hyper trophy, Burggren and Mwalukoka studie gill and skin morphometrics of bullfrog larvae, the held the larvae for 28 days in 3 different conditions, high Po2 >275 torr (hyperoxic) normal po2 = 150 torr normoxic and low po2 = 70-80 torr, hypoxic, he found that gill filaments grew larger in hypoxic water than normoxic area to increase surface area for gas exchange |
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Plasticity of skin surface area and thickness |
In 1941, Krogh demonstrated phenotypic plasticity (raised tadpoles in different O2 levels) of amphibian fills: hypoxia led to hyper trophy, Burggren and Mwalukoka studie gill and skin morphometrics of bullfrog larvae, the held the larvae for 28 days in 3 different conditions, high Po2 >275 torr (hyperoxic) normal po2 = 150 torr normoxic and low po2 = 70-80 torr, hypoxic, he found that gill filaments grew larger in hypoxic water than normoxic area to increase surface area for gas exchange, also in the hypoxic water the capillaries where larger and closer to the skin surface, in normal water the capillaries where only found in the dermis |
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Hypoxia |
Led to more branching in the lungs, larger capillaries that where closer to the skin surface and larger gill filaments |
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Gills |
Evaginations of tissue (salamander) protruding into the external medium (can be internal in some cases), they are delicate structures composed of thin cell layers (protected by shells, toxins, withdrawal, exoskeleton and bony plates), they are highly persuaded by a circulatory system, they may have flow through breathing |
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Protection and other uses for gills |
Cavities protect gills and water is pumped across them, some gills are used for feeding, some animals eat jellyfish and sequester its sting and then sting animals if they attack, in crabs gills are attached to basal pores of the leg which are hard for predators to access (water enters the exoskeleton and circulates over the gills) |
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Protection and other uses for gills |
Cavities protect gills and water is pumped across them, some gills are used for feeding, some animals eat jellyfish and sequester its sting and then sting animals if they attack, in crabs gills are attached to basal pores of the leg which are hard for predators to access (water enters the exoskeleton and circulates over the gills) |
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Muscle driven resting (cephalopods such as octopus and squid) |
During inhalation the funnel closes and the mantle cavity expands drawing water in, during exhalation the mantle opening seals up, the mantle contracts and the funnel opens expelling water out of the siphon, this is also used for jet propulsion, water movement basically flows in through collar (a little above eye) then through the gill, mantle cavity and then out the funne |
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Muscle driven breathing in fishes |
Skeletal muscle pumps in Buccal and opercular cavities (covering of gills that opens and closes), mouth and throat open and oxygen rich water is drawn into mouth by negative pressure, then the mouth closes ,the opercular cavity constricts and the opercula open, thus forcing water through the gills and out the opercular exit (this is due to pressure forcing opercular to open) |
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Lamprey and breathing |
Lamprey uses today flow in and out of the opercular opening, because it's mouth remains attached to the host while feeding |
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Operculum |
A bony structure that covers the gills of most fish |
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Fish breathing |
Water flows in through mouth, then over the gills and then out |
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Fish inhalation |
Water coming in due to negative pressure in the buccal cavity, at this point the lid is closed |
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Fish inhalation |
Water coming in due to negative pressure in the buccal cavity, at this point the lid is closed |
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Fish exhalation |
The mouth closes and positive pressure in the buccal cavity causes the opercular cavity to constrict and the lid or opercular open, forcing water through the gills and out the opercular exit |
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Water flowing over gills |
Water flows across the gill filament, there is a counter current flow across the gills, oxygen enriched blood is sent out of the filament through ephrin and oxygen poor blood is sent into the filament through aphrin, the oxygen is diffused through the lamella into the blood |
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Concurrent vs countercurrent |
In concurrent blood flow the concentration gradient is high in the beginning but it equilibrates down the road, countercurrent flow maximizes efficiency of gas exchange across gill filaments due to always having a concentration gradient due to blood picking up more oxygen the longer the distance |
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Concurrent vs countercurrent |
In concurrent blood flow the concentration gradient is high in the beginning but it equilibrates down the road, countercurrent flow maximizes efficiency of gas exchange across gill filaments due to always having a concentration gradient due to blood picking up more oxygen the longer the distance |
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Countercurrent blood flow |
Efficient due to constant pressure gradient, it enhances the gas pressure gradient, it means blood flow in a direction opposite to that of water flow, blood continually encounters water whose oxygen content is higher, much more efficient than concurrent blood flow |
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Ram ventilation |
Bull transport is created by the animals swimming motion, obligate ram breathes such as tuba and sharks must swim in order to breathe which is why they are constantly moving or they will suffocate, facultative ram breathers such as the rainbow trait can switch from buccal opercular breathing to ram ventilation when swimming above certain velocities, sharks will sit still in ravines so water automatically goes through then |
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Air vs water respirers |
Air is much less viscous than water water allowing for easier bulk transport, air contains more oxygen than water reducing the need for surface area which permits less efficient tidal breathing, remember that thin respiratory surfaces exposed to air must be kept moist (there will be no diffusion across dry surfaces), therefore air respirers remain in a moist environment or have covered or fully internal gas exchange structures |
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Arthropods (Book lungs) |
Scorpions and some spiders have book lungs (layers that look like book pages, evolved from book gills), they are stacks of lamellae invaginating from the cuticle into the abdomen, |
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Arthropods (tracheae) |
Insects and many spiders have little tubes called trachea, they are tubular extensions into the tissues reinforced with rings of chitin (the tubes exit on body of insect), once in the break up into finer branches (tracheoles), the tracheae connect to the outside through openings in the exoskeleton called spiracles, the distribution of the tracheae reflects then oxygen demand of tissues (muscles needing more oxygen), larger and flying insects have active tidal pumping of air (air is brought and carried through the tracheal system directly to the muscle, they don't use hemolymph to transport oxygen), while no hemolymph is used there is still some fluid to aid with gas exchange |
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Arthropods (tracheae) |
Insects and many spiders have little tubes called trachea, they are tubular extensions into the tissues reinforced with rings of chitin (the tubes exit on body of insect), once in the break up into finer branches (tracheoles), the tracheae connect to the outside through openings in the exoskeleton called spiracles, the distribution of the tracheae reflects then oxygen demand of tissues (muscles needing more oxygen), larger and flying insects have active tidal pumping of air (air is brought and carried through the tracheal system directly to the muscle, they don't use hemolymph to transport oxygen), while no hemolymph is used there is still some fluid to aid with gas exchange |
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Flight muscles |
Many fast flying insects use flight muscles that receive the most oxygen per second of any known animal muscle, up to 200x faster than in mammals! Tracheal system pumps air directly to muscles |
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Larger insects in past |
Likely due to higher oxygen levels on the past (35%) vs (21%) today, trachea size is another limiting factor |
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Larger insects in past |
Likely due to higher oxygen levels on the past (35%) vs (21%) today, trachea size is another limiting factor |
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Air respirers: Bimodal breathers |
The first air breathers may have evolved in tropical lowlands where stagnant ponds were subject to hypoxia or desiccation, bimodal breathers have gills and other respiratory exchange structures such as their skin, lungs in fishes were simple ventral evaginations of the pharynx |
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Lingfish |
Freshwater fish found in different continents, some are obligate air breathers, they are found in different continents due to Pangaea which assembled about 300 mya and broke apart 175 mya, lungfish gave rise to terrestrial tetrapods |
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Amphibians |
Can be bimodal or Trimodal air breathers (gills,lungs and integument) to support aquatic and terrestrial lifestyles, in frogs larval stages have gills and adults have simple noncompertalized lungs (from simple to complex), air is forced into lungs by positive pressure from a buccal pump (lowering or raising of pharynx, negative pressure into nostrils, then nostrils close), oxygen goes through lungs and carbon dioxide is eliminated through skin due to moisture, several inspiratory oscillations fill lungs then they empty in one lung exhalation, adaptation to air breathing included a decrease in affinity of hemoglobin to oxygen due to much greater oxygen availability in air |
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Air breathing reptiles |
Lungs in reptiles, birds and mammals are compartmentalized and fill by negative pressure ( drawn into lungs like a vacuum), reptile lungs are expandable, tidally ventilated sacs (except for crocodiles and birds), vascularized ingrowths or dividing walls (septa) subdivide pulmonary lumen, the air sacs are called ediculae which are spherical shape or faveoli which are oblong shaped |
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Snakes |
Snakes have right lost lung lobe, the faveoli increases surface area, big surface area and small distance facilitates diffusion in conjunction with moisture |
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Ventilation in vertebrates |
Positive pressure breathing (fish and amphibians due to pharynx contracting and forcing water through gills in fish and to lungs in amphibians) Negative pressure breathing (reptiles, mammals and birds)
Breathing refers to how air enters or passes across the gas exchanger |
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Air respirers reptiles continued |
Lizards and snakes rely on coastal (rib) muscles for expansion of lungs (they are in between ribs and allows passive exhalation), turtles that have fixed ribs use limb extensions, crocodilians have a connective tissue diaphragm adhering tightly to the anterior surface of the liver (a modified flow through system similar to birds), the diaphragmaticus muscle contracts during inhalation with a flow through system in second and tertiary bronchi |
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Air respirers reptiles continued |
Lizards and snakes rely on coastal (rib) muscles for expansion of lungs (they are in between ribs and allows passive exhalation), turtles that have fixed ribs use limb extensions, crocodilians have a connective tissue diaphragm adhering tightly to the anterior surface of the liver (a modified flow through system similar to birds), the diaphragmaticus muscle contracts during inhalation with a flow through system in second and tertiary bronchi |
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Diaphraghmaticus muscle |
Attached between liver and pubis bone in crocodilians, contracts and pulls the liver expanding the lungs along with the intercostal muscles (passive inhalation) |
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Lung types |
Amphibian: salamander similar to fishes, adult frogs adapted to dry habitats Reptile: lizard adapted to dry habitats Mammal: human adapted to dry habitats and we have alveoli
Saccular (lungfish,amphibians and some reptiles, not involved on gas exchange but they might store air and controls movement of air) Alveolar (some reptiles and mammals) Parabronchial (birds) |
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Birds and mammals |
Surface area of lungs for gas exchange is expanded to support increased metabolic rates (very small alveoli in mammals and parabronchi with air capillaries in birds) Oxygenated blood from lung is completely separated from systemic venous blood by four chambered heart (also in crocodiles) Small percentage of skin breathing in most mammals (1-2%) but 12% carbon dioxide release in bats across surface of their wings due to thin wing membrane, oxygen can't be brought in though |
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Mammalian airways |
I'm the nasal passages, maxilloturbinals (turbinate bones) retain heat and water, these are inside the nose and are very important for animals in dry habitats The pharynx is a common passageway for air and food The trachea and esophagus exit the pharynx (reflexes close off trachea during swallowing) The trachea divides into right and left bronchi, each entering a lung. The bronchi branch with lungs, the trachea ad large bronchi are supported by cartilaginous rings which keep them open Bronchioles are smaller branches, terminal bronchioles open into the alveoli where gas exchange occurs in mammals, also walls contain smooth muscle innervated by the autonomic nervous system (involuntary muscles) |
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Diaphragm |
In mammals it's contraction and depression cause negative pressure, in conjunction with our intercostals which also play an important role |
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Diaphragm |
In mammals it's contraction and depression cause negative pressure, in conjunction with our intercostals which also play an important role |
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Alveolar sac |
Can be different sizes and is where gas diffusion occurs |
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Capillaries |
Mesh of capillaries wraps alveolus and air exchange occurs from capillaries to alveoli through diffusion |
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Alveoli |
Very small and tidally ventilated sacs, this is where gas exchange occurs due to the large surface area, the single layer of highly flattened Type I alveolar cells, dense network of capillaries surrounding alveoli, thin interstitial space, achieving partial pressures of gases in blood comparable to those in inspired air
Type II alveolar cells secrete pulmonary surfactant which facilitates alveolar expansion (contracting and expanding)
Pores of Kohn permit airflow between adjacent alveoli (collateral ventilation) |
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Alveoli |
Very small and tidally ventilated sacs, this is where gas exchange occurs due to the large surface area, the single layer of highly flattened Type I alveolar cells, dense network of capillaries surrounding alveoli, thin interstitial space, achieving partial pressures of gases in blood comparable to those in inspired air
Type II alveolar cells secrete pulmonary surfactant which facilitates alveolar expansion (contracting and expanding)
Pores of Kohn permit airflow between adjacent alveoli (collateral ventilation) |
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Type II alveolar cells |
Secrete pulmonary surfactant |
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Respiratory cycle |
Inspiration involves contraction of inspiratory muscles (diaphragm contracts downward (flattens) and external intercostal muscles expands ribs outward which enlarges the thoracic cavity
Exhalation normally involves relaxation of inspiratory muscles (diaphragm bows) and elastic recoil of chest wall and lungs
Active exhalation involves contraction of abdominal wall muscles and internal intercostal muscles |
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Before inspirstion |
External intercostal muscles and diaphragm relaxed |
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Active inspiration |
Elevated rib cage, elevation of ribs causes sternum to move upward and outward which increases front to back dimensions of thoracic cavity, contraction of external intercostal muscles causes elevation of ribs which increases side to side dimension of thoracic cavity, lowering of diaphragm on contraction increases vertical dimension of thoracic cavity, contraction of diaphragm and external intercostal muscles |
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Passive expirstion |
Relaxation of external intercostal muscles and diaphragm, return of diaphragm, ribs and sternum to resting position on relaxation of inspiratory muscles restores thoracic cavity to preinspiratory size |
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Passive expirstion |
Relaxation of external intercostal muscles and diaphragm, return of diaphragm, ribs and sternum to resting position on relaxation of inspiratory muscles restores thoracic cavity to preinspiratory size |
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Active expiration |
Contraction of internal intercostal muscles, contraction of abdominal muscles, contraction of internal intercostal muscles flattens ribs and sternum, further reducing side to side and front to back dimensions of thoracic cavity, contraction of abdominal muscles causes diaphragm to be pushed upward which further reduces vertical dimension of thoracic cavity |
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Birds |
Complete separation of ventilation and gas exchange Lungs are smaller than in mammals and inelastic (don't change) Ventilation of expandable air sacs perform tidal function without gas exchange Air enters nasal passages, trachea, bronchi and air sacs (instead of lungs) Bronchi gives rise to secondary bronchi (air flows from dorsobronchi to ventrobronchi through parallel parabronchi) Air capillaries branch from parabronchi (where gas exchange occurs) |
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Bird breathing cycles |
2 cycles, for air to go through we need 2 inhalations and exhalations
Inspiration 1: air is brought in by primary bronchus and through mesobronchus bringing air into the posterior air sac which expands creating negative pressure and some air also goes up to the mediodorsal bronchus
Expiration 1: air is forced through the medioventral bronchus
Inspiration 2: air is brought in the same as the first inspiration but as the same time air is forced into the anterior air sac as well creating negative pressure there
Expiration 2: forces air out of mouth or nose, one way valves probably prevent backflowb |
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Bird breathing cycles |
2 cycles, for air to go through we need 2 inhalations and exhalations
Inspiration 1: air is brought in by primary bronchus and through mesobronchus bringing air into the posterior air sac which expands creating negative pressure and some air also goes up to the mediodorsal bronchus
Expiration 1: air is forced through the medioventral bronchus
Inspiration 2: air is brought in the same as the first inspiration but as the same time air is forced into the anterior air sac as well creating negative pressure there
Expiration 2: forces air out of mouth or nose, one way valves probably prevent backflowb |
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Ostrich lungs |
Deeply entrenched into the ribs, you can see the ridge where the ribs enter/bridge with lungs, therefore we know they don't expand |
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Pneumatic bones |
Birds have them, they are hollow ones that have air filled cavities, allows more Po2 than what is outside, they aren't completely hollow (have struts for support), air sacs in bones connected to respiratory system, major bones of body are pneumatic, bones can be pneumatized by either forward or rear sacs |
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Pneumatic bones |
Birds have them, they are hollow ones that have air filled cavities, allows more Po2 than what is outside, they aren't completely hollow (have struts for support), air sacs in bones connected to respiratory system, major bones of body are pneumatic, bones can be pneumatized by either forward or rear sacs |
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Air capillaries vs alveoli |
Air capillaries are narrower than alveoli, epithelial cells are thinner, flow through design is more efficient, rigid lungs so resistant to damage, crosscurrent blood flow in parabronchi provides more efficient uptake of oxygen |
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Crosscurrent flow in the avian parabronchus |
Gradient is still opposite, blood capillary had a diffusion barrier with air capillary |
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Dinosaurs |
Dinosaurs showed signs of pneumatic bones |
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Dinosaurs |
Dinosaurs showed signs of pneumatic bones |
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Nonrespiratory functions of aerial respiratory systems |
Regulation of water loss and heat exchange (moistening of inspired air is essential to prevent desiccation of respiratory surfaces), improved venous return (respiratory pump), acid-base balance, defense against inhaled foreign matter, removal or modification or activation or inactivation of substances passing through the pulmonary circulation, olfaction, vocalization (larynx in mammals and syrinx in birds - the number of syringial muscles related to complexity of song |
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Dinosaurs |
Dinosaurs showed signs of pneumatic bones |
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Nonrespiratory functions of aerial respiratory systems |
Regulation of water loss and heat exchange (moistening of inspired air is essential to prevent desiccation of respiratory surfaces), improved venous return (respiratory pump), acid-base balance, defense against inhaled foreign matter, removal or modification or activation or inactivation of substances passing through the pulmonary circulation, olfaction, vocalization (larynx in mammals and syrinx in birds - the number of syringial muscles related to complexity of song |
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Larynx vs syrinx |
Mammalian larynx sits at the junction of the pharynx and trachea Avian syrinx sits at the trachea - bronchi junction (farther down but have the same function) |
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Pressure is important in mammalian lung ventilation |
Intra alveolar pressure is 760 mmHg, intrapleural is 756 mmHg, transmural pressure gradient across the thoracic wall equals the atmospheric pressure minus intrapleural pressure and the the transmural pressure gradient across a lung wall equals intra alveolar pressure minus intrapleural pressure
From outer: thoracic wall, pleural cavity, lung wall, lungs (alveoli) |
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Pressure is important in mammalian lung ventilation |
Intra alveolar pressure is 760 mmHg, intrapleural is 756 mmHg, transmural pressure gradient across the thoracic wall equals the atmospheric pressure minus intrapleural pressure and the the transmural pressure gradient across a lung wall equals intra alveolar pressure minus intrapleural pressure
From outer: thoracic wall, pleural cavity, lung wall, lungs (alveoli) |
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Boyles law |
Pressure exerted by a gas varies inversely with the volume of gas |
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Pressure is important in mammalian lung ventilation |
Intra alveolar pressure is 760 mmHg, intrapleural is 756 mmHg, transmural pressure gradient across the thoracic wall equals the atmospheric pressure minus intrapleural pressure and the the transmural pressure gradient across a lung wall equals intra alveolar pressure minus intrapleural pressure
From outer: thoracic wall, pleural cavity, lung wall, lungs (alveoli) |
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Boyles law |
Pressure exerted by a gas varies inversely with the volume of gas |
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Breathing mechanisms in mammals |
Before inspiration: 760 mmHg in lungs and 756 in pleural cavity
During inspiration: 759 in lungs, 754 in cavity due to volume increasing with inspiration
During expiration: 761 in lungs and 756 in pleural, difference in pressure gradient moves air out towards 760 atm |
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Mammal airway resistance |
Airway resistance is normally low, depends on radius of the conducting system, the pressure gradients of 1-2 mmHg produce adequate rates of air flow, diseases causing narrowing of airways greatly increase resistance and the work of breathing |
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Diseases that narrow airways |
Chronic obstructive pulmonary disease (COPD) - chronic bronchitis, asthma, emphysema Equine restrictive lung disease
Chronic bronchitis causes inflammation and excess mucus in bronchi
Emphysema causes alveolar membranes to break down reducing the overall surface area |
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Diseases that narrow airways |
Chronic obstructive pulmonary disease (COPD) - chronic bronchitis, asthma, emphysema Equine restrictive lung disease
Chronic bronchitis causes inflammation and excess mucus in bronchi
Emphysema causes alveolar membranes to break down reducing the overall surface area |
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Elasticity of lungs |
Depends on connective tissue and alveolar surface tension
The pulmonary connective tissue contains large amounts of elastin (rebound after being stretched)
Alveolar surface tension is reduced by pulmonary surfactant which acts as an anti glue, it increases pulmonary compliance, reduces the lungs tendency to recoil and prevents the collapse of smaller alveoli (predicted by Laplace's law: P = 2T/r) this is due to alveoli being different sizes and the smaller might collapse due to surface tension, pulmonary surfactants reduce the recoil tendency |
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Diseases that narrow airways |
Chronic obstructive pulmonary disease (COPD) - chronic bronchitis, asthma, emphysema Equine restrictive lung disease
Chronic bronchitis causes inflammation and excess mucus in bronchi
Emphysema causes alveolar membranes to break down reducing the overall surface area |
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Elasticity of lungs |
Depends on connective tissue and alveolar surface tension
The pulmonary connective tissue contains large amounts of elastin (rebound after being stretched)
Alveolar surface tension is reduced by pulmonary surfactant which acts as an anti glue, it increases pulmonary compliance, reduces the lungs tendency to recoil and prevents the collapse of smaller alveoli (predicted by Laplace's law: P = 2T/r) this is due to alveoli being different sizes and the smaller might collapse due to surface tension, pulmonary surfactants reduce the recoil tendency |
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Law of LaPlace |
Magnitude of inward directed pressure (P) in a bubble (alveolus) = 2 x surface tension (T)/radius (r) of bubble (alveolus) |
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Alveoli and tension |
A smaller alveoli would push air into the bigger alveoli without surfactant due to a more pressure in the smaller ones, with surfactants the pressure is equivalent |
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Alveoli and tension |
A smaller alveoli would push air into the bigger alveoli without surfactant due to a more pressure in the smaller ones, with surfactants the pressure is equivalent |
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Spirometers |
Used to record lung volumes and capacities |
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Lung volume and capacities |
Total lung capacity (TLC) = maximum amount of air that the lungs can hold (5.7 L) Tidal volume (TV) = volume of air entering or leaving the lungs during a single breath (resting TV - 0.5ml) it can inc or dec Functional residual capacity (FRC) - volume of air in the lugs at the end of a normal passive expiration (2.2 L) Residual volume (RV) - minimum volume of air remaining in the lungs after a maximal expiration (1.2 l) Vital capacity (VC)- maximum volume of air that can be moved out during a single breath following maxima inspiration (4.5 l)
All of these are higher in a horse |
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Pulmonary ventilation |
Also known as minute ventilation Pulmonary ventilation (L/min) = Tidal volume (L/breath) x respiratory rate (breaths/min)
It scales with body mass (size) Tidal volume increases with increasing body mass (mass in kg), while respiratory rate decreases with increasing body mass
Tidal volume is almost exactly proportional to body mass (1.01). However respiratory rate scales with body mass, larger animals have slower rates
A giraffe actually has a slower respiratory rate than a horse but still much less than a human who is around 15 |
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Pulmonary ventilation |
Also known as minute ventilation Pulmonary ventilation (L/min) = Tidal volume (L/breath) x respiratory rate (breaths/min)
It scales with body mass (size) Tidal volume increases with increasing body mass (mass in kg), while respiratory rate decreases with increasing body mass
Tidal volume is almost exactly proportional to body mass (1.01). However respiratory rate scales with body mass, larger animals have slower rates
A giraffe actually has a slower respiratory rate than a horse but still much less than a human who is around 15 |
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Increasing pulmonary resporstion |
It is usually more advantageous to have a greater increase in tidal volume than in respiratory rate because of the presence of an atomic dead space |
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Pulmonary ventilation |
Also known as minute ventilation Pulmonary ventilation (L/min) = Tidal volume (L/breath) x respiratory rate (breaths/min)
It scales with body mass (size) Tidal volume increases with increasing body mass (mass in kg), while respiratory rate decreases with increasing body mass
Tidal volume is almost exactly proportional to body mass (1.01). However respiratory rate scales with body mass, larger animals have slower rates
A giraffe actually has a slower respiratory rate than a horse but still much less than a human who is around 15 |
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Increasing pulmonary resporstion |
It is usually more advantageous to have a greater increase in tidal volume than in respiratory rate because of the presence of an atomic dead space |
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Alveolar ventilation |
When increasing pulmonary ventilation (during activity), it is advantageous to have a greater increase in tidal volume than respiratory rate because not all inspired air reaches the alveoli for gas exchange (some stuck in trachea), this is known as the anatomic dead space which is the volume of conducting passages (.15L), alveolar ventilation is the volume of air exchanged between the atmosphere and alveoli per minute The alveolar ventilation is equal to (TV - dead space) x RR, in other words how much actually reaches alveoli which is roughly 15% |
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Breathing and dead space |
There is about 150 mL of dead space in airway, during inspiration we get 150 ml of old air and 350 ml of fresh air for a total 500 ml from atmosphere, during expiration 150 ml left in dead space that is oxygen deprived, 150 ml fresh air exhaled from dead space and 350 ml alveolar oxygen deprived air |
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Flow through vs tidal respirers |
Comparative efficiency Flow through systems have much lower dead space volumes than tidal systems Partial flow through systems in birds have higher dead space volumes due to the larger size of the trachea but to compensate for this a bird has a higher tidal volume and lower respiration rate than a mammal of comparable size Only 2% of total energy is expended on quiet breathing in mammals, there is a 25 fold increase in energy requirement for pulmonary ventilation during strenuous activity increase percentage to 5% 20% of total energy is expended on respiration in fish The tidal lung of mammals can only achieve a blood pressure of oxygen equal to that of expired air (25% efficiency of oxygen extraction from air) In birds (partially tidal with dead spaces and crosscurrent blood flow) efficiency is 30-40% Countercurrent blood flow in fish, crustaceans and amphibians yields 90% of oxygen extraction efficiency from water (however oxygen content is lower in water) |
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Lung air pressure is lower than inspired atmospheric air for two reasons |
Saturated with water and mixed with air from dead space |
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Lung air pressure is lower than inspired atmospheric air for two reasons |
Saturated with water and mixed with air from dead space |
