RespirationRespiration

Gas Exchange requires moist Gas Exchange requires moist surfacessurfaces

Gills (left), Alveoli (right)

P. 871P. 871

Gas ExchangeGas Exchange

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Gill Structure and FunctionGill Structure and Function

a. Gills are skin projections into which coelomic fluid moves.

b. Parapodia are used for gills, swimming, crawling.

c. Long, flattened page-like tissues.

d. Feathery gills under exoskeleton.

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InsectsInsects

Have spiracles leading to Have spiracles leading to trachea (branched tubes)trachea (branched tubes)

Air sacs are present near Air sacs are present near organsorgans

Pix 42.22Pix 42.22

Gills in FishGills in Fish

Water is pumped through the mouth and over gill arches. Each gill arch has 2 filaments made of plate like lamellae.

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Countercurrent ExchangeCountercurrent Exchange

Blood picks up more and more oxygen as the water has higher and higher concentrations. (oxygen poor vessels on right, oxygen rich vessels on left)

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Bird RespirationBird Respiration

Air sacs maximize oxygen withdrawal from air.

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Negative Pressure BreathingNegative Pressure Breathing

Air is pulled (not pushed) into the lung. On inhalation the volume of the thoracic cavity is increased- decreasing pressure-air rushes in.

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TerminologyTerminology

Tidal Volume-volume inhaled and exhaled Tidal Volume-volume inhaled and exhaled per breath.per breath.

Vital Capacity-Maximum tidal volume Vital Capacity-Maximum tidal volume (forced).(forced).

Residual volume-the air that cannot be Residual volume-the air that cannot be expelled from the lungs.expelled from the lungs.

Breathing Control CentersBreathing Control CentersTwo regions of the brain-medulla oblongata and pons.

Medulla set rhythm, monitors carbon dioxide levels in blood (mostly using pH) and adjust breathing as needed.

CO2 + water forms carbonic acid-lowers pH. Low pH triggers increased breathing rate and depth.

Very low O2 sensors in aorta and carotid respond with signal to breathing centers-breathing rate increases.

Hyperventilation- very deep breathing may purge blood of carbon dioxide-stops impulses to expand thorax until levels build up. Bypasses usual set-up-Co2 and O2 levels are related.

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Gas ExchangeGas ExchangeGas diffuses down pressure gradients.

Partial Pressures are the portions of atmospheric pressure contributed by individual gases. e.g.:

air is 21% oxygen.

Pressure of atmosphere is 760 mmHg

PP of O2 is .21 x 760= 160mmHg

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More Partial PressureMore Partial Pressure

Gas will always diffuse from a higher Gas will always diffuse from a higher partial pressure to a lower partial pressure.partial pressure to a lower partial pressure.

At the lung the PAt the lung the PO2O2 in the blood is low and in the blood is low and the Pthe PO2O2 in the lung is higher so oxygen in the lung is higher so oxygen moves into the blood.moves into the blood.

At the lung the PAt the lung the PCO2CO2 in the blood is higher in the blood is higher than in the lung, so carbon dioxide moves than in the lung, so carbon dioxide moves into the lung from the blood.into the lung from the blood.This works at the tissues too. This works at the tissues too.

Hemoglobin Dissociation CurveHemoglobin Dissociation Curve

Hemoglobin is a respiratory pigment (protein) which carries oxygen. Arthropods have hemocyanin.

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HemoglobinHemoglobin

Made of four subunits, each with a cofactor called a Made of four subunits, each with a cofactor called a heme group and each with an iron atom at the center. heme group and each with an iron atom at the center. The binding of oxygen with one subunit causes a shape The binding of oxygen with one subunit causes a shape change which causes the other three to bind more change which causes the other three to bind more easily. This is cooperativity.easily. This is cooperativity.This is seen in the dissociation curve for hemoglobin This is seen in the dissociation curve for hemoglobin over different partial pressures of oxygen. When the over different partial pressures of oxygen. When the partial pressure falls the hemoglobin hangs onto the partial pressure falls the hemoglobin hangs onto the oxygen until it is pretty low, then lets go of all of it at oxygen until it is pretty low, then lets go of all of it at once.once.

The Bohr shift shows an increase in oThe Bohr shift shows an increase in o22 release when the release when the pH is lower-more carbon dioxide.pH is lower-more carbon dioxide.

Blood CO2 TransportBlood CO2 TransportCO2 is carried to the lungs in a variety of ways.

7% is carried in the blood plasma

23% binds to amino groups of hemoglobins

70% is carried as bicarbonate ions in the blood.

CO2 diffuses into blood plasma then into RBC’s where it is converted to bicarbonate

CO2 first reacts with water (enzyme here is carbonic anhydrase) to form carbonic acid. Most H+ attach to hemoglobin. Bicarbonate diffuses out into plasma.

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Hemoglobin CurvesHemoglobin Curves

In fetusIn fetus

Special AdaptationsSpecial Adaptations

Oxygen storage in blood Oxygen storage in blood and muscle may be and muscle may be doubled.doubled.Less left in lung 36% to Less left in lung 36% to 5% in seal5% in sealSpleen is large and may Spleen is large and may store huge amounts of store huge amounts of blood.blood.Lots of myoglobin- an Lots of myoglobin- an oxygen storing protein- in oxygen storing protein- in musclemuscleConserve oxygenConserve oxygenATP from fermentationATP from fermentation