Respiratory System - A Quick Tour

• General Function

• Aquatic systems

• Land systems

• Insect

• Amphibian

• Mammalian

•Introduction - the search for SA (gas

exchange)

• Size of respiratory surface area is a function of organism’s metabolic needs....though all are

1. thin and have large surface areas.

2. Must remain moist (advantages/disadvantages)..

3. Who has larger SA to body mass ratio? ENDO or ECTOtherms??

• Gills are outfoldings of the body surface that are suspended in water.

• The total surface area of gills is often much greater than that of the rest of the body.

Gills are respiratory adaptation of most aquatic animals

• Many variations. Gill Flavors..• Many segmented worms

have flaplike gills.

• The gills of clams, crayfish, and many other animals are restricted to a local body region (more like us).

Fig. 42.19

The good and the bad..• Water has both advantages and disadvantages as a

respiratory medium.

• ADVANTAGE

• moist.

• DISADVANTAGE

• Low gas concentration, heavy .

• Thus, gills must be very effective to obtain enough oxygen (surface area exaggerated or metabolic rate suffers).

Fig. 42.20

• This flow pattern is countercurrent exchange Essay stuff.

• Explain this

• Other examples

• Lacteal

• Thermoregulation

• All along the gill capillary, there is a diffusion gradient

• What would happen the other way?

Fig. 42.20

ESSAY (BE ABLE TO EXPLAIN THIS)

• As a respiratory medium, air has many advantages over water.

• What are they?

• ventilation requires less energy…:)

• Note; recent geologic findings indicate higher 02 concentrations 150-50 million years bp!!!!

• Who would have benefited?

Terrestrial animals LUNGSADVANTAGES

• Air does have problems as a respiratory medium.

• What are they?

Terrestrial animals LUNGSDISADVANTAGES

Really Small Land Animals..• The tracheal system of insects is composed of air

tubes that branch throughout the body.

• The largest tubes, called tracheae, open to the outside, and the finest branches extend to the surface of nearly every cell. (A systemic system)

• The open circulatory system does not actively transport oxygen and carbon dioxide.

• Explain WHY the tracheal system is well adapted to the open circulatory system…

Fig. 42.22

Larger Land Animals:

Lungs• Specialized Exchange Surfaces…

•TISSUE??

•CELLS?

• lungs are restricted to one location….need for an efficient “closed” circulatory system - see the connection?

• The respiratory surface of the lung is outside of body.

• Lungs have evolved in spiders, terrestrial snails, and vertebrates.

• Among the vertebrates, amphibians have relatively small lungs that do not provide a large surface (many lack lungs altogether).

• Why are amphibians so susceptible to air quality??.

• Most reptiles and all birds and mammals rely entirely on lungs for gas exchange.

• Turtles may supplement lung breathing with gas exchange across moist epithelial surfaces in their mouth and anus !?. I think air goes the other way for us

Fig. 42.23

Review and know gas pathway in lungs…

• SURFACE AREA IN LUNGS

• At their tips, the tiniest bronchioles dead-end as a cluster of air sacs called alveoli.

• Gas exchange occurs across the thin epithelium of the lung’s millions of alveoli.

• These have a total surface area of about 100 m2 in humans.

• Oxygen in the air entering the alveoli dissolves in the moist film and rapidly diffuses across the epithelium into a web of capillaries that surrounds each alveolus.

• Carbon dioxide diffuses in the opposite direction.

• HOW DO WE BREATH???

• The process of breathing, the alternate inhalation and exhalation of air, ventilates lungs.

• A frog ventilates its lungs by positive pressure breathing (the big bubble)

• Muscle activity forces air into lungs.

• Note – air force pilots are taught to do this in emergency situations – valsalva maneuver

• mammals ventilate their lungs by negative pressure breathing.

• This works like a suction pump, pulling air instead of pushing it into the lungs.

• Muscle action changes the volume of the rib cage and the chest cavity,and the lungsfollow suit.

Fig. 42.24

• The lungs are enclosed by a double-walled sac (pleura), A thin space filled with fluid separates the two layers.

• Because of surface tension, the two layers behave like two sheets of saran wrap stuck together by the adhesion and cohesion of a film of water.

• The layers can slide smoothly past each other, but they cannot be pulled apart easily.

• Surface tension couples movements of the lungs to movements of the rib cage.

BREATHING….• Lung volume increases as a result of contraction

of the rib muscles and diaphragm, a sheet of skeletal muscle that forms the bottom wall of the chest cavity.

• Contraction of the rib muscles (internal and external intercostal muscles) expands the rib cage by pulling the ribs upward and the breastbone outward.

• At the same time, the diaphragm contracts and descends like a piston.

• Because air flows from higher pressure to lower pressure, air rushes into the respiratory system.

BREATHING….• During exhalation, the rib muscles and diaphragm

relax.

• The lungs behave as an inflated, untied, freshly liberated (released) balloon (well, they don’t actually fly out of the chest).

• Due to “elastic recoil of lungs.

• Lost with emphysema

• This forces air up the breathing tubes and out through the nostrils.

• The volume of air an animal inhales and exhales with each breath is called tidal volume.

• It averages about 500 mL in resting humans.

• The maximum tidal volume during forced breathing is the vital capacity, which is about 3.4 L and 4.8 L for college-age females and males.

• The lungs hold more air than the vital capacity, but some air remains in the lungs, the residual volume, because the alveoli do not completely collapse.

• PROBLEM WITH MAMALLIAN RESPIRATION

• Same as the problem of the gastrovascular cavity in digestion – one opening, two way transport.

• Ventilation is much more complex in birds than in mammals (more efficient).

• Besides lungs, birds have eight or nine air sacs that do not function directly in gas exchange, but act as bellows that keep air flowing through the lungs - one way flow - less mixing of old air (think of three chambered heart).

• Instead of alveoli, which are dead ends, the sites of gas exchange in bird lungs are tiny channels called parabronchi, through which air flows in one direction.

• Partly because of this efficiency advantage, birds perform much better than mammals at high altitude. - why is this a good thing??

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Fig. 42.25

• Sure you can hold your breath..but do you really have control??.

• Coordination of Respiration and Circulation

Control centers in the brain regulate the rate and depth of breathing

• Our breathing control centers are located in two brain regions, the medulla oblongata and the pons.

• Aided by the control center in the pons, the medulla’s center sets basic breathing rhythm, triggering contraction of the diaphragm and rib muscles.

• A negative-feedback mechanism via stretch receptors prevents our lungs from overexpanding by inhibiting the breathing center in the medulla.

Fig. 42.26

Where is conscience thought??

• The medulla’s control center monitors the CO2 level of the blood

• Its main cues about CO2 concentration come from slight changes in the pH

• How is pH related to CO2??

• Oxygen concentrations in the blood usually have little effect of the breathing control centers.

• Realize….Deep, rapid breathing purges the blood of so much CO2 –

how does this cause hyperventilation??

Respiratory pigments transport gases and help buffer the blood

Realize different approaches..

hemocyanin, found in the hemolymph of arthropods and many mollusks, has copper (get it?) as its oxygen-binding component, coloring the blood bluish.

• Respiratory pigments• Hemoglobin – most vertebrates.

• Hemoglobin consists of four subunits, each with a cofactor called a heme group that has an iron atom at its center.

• Because iron actually binds to O2, each hemoglobin molecule can carry four molecules of O2.

• Wow, what’s the other molecule?? This is my favorite molecule

• Remember; hemoglobin must bind oxygen reversibly,.

• What would be the consequence if not ??

• Do any substances bind irreversibly?

• Cooperative oxygen binding and release is evident in the dissociation curve for hemoglobin.

• What part of curve represents lung conditions?.

• What part represents body conditions?

Fig. 42.28a

• BOHR SHIFT!!!• As with all proteins,

hemoglobin’s conformation is sensitive to a variety of factors.

• pH effect on hemoglobin = Bohr shift.

• Why is Bohr shift important during exercise??.

free response!!

• Given what you know (and appreciate) about hemoglobin/oxygen binding, draw a graph showing the dissociation curves of adult hemoglobin, fetal hemoglobin, and myoglobin. Your graph should be correctly labeled (X, Y axis, Title). Explain how your graph indicates the relationship of these three molecules as they function to transport oxygen. Hand in at end of hour!!! (really)

hemoglobin also transports carbon dioxide and assists in buffering blood

pH.

• About 7% of the CO2 released by respiring cells is transported in solution.

• Another 23% binds to amino groups of hemoglobin.

•About 70% is transported as bicarbonate ions.

• Carbon dioxide from respiring cells diffuses into the blood plasma and then into red blood cells, where some is converted to bicarbonate, assisted by the enzyme carbonic anhydrase.

• Fastest enzyme in the body!!!

• At the lungs, the equilibrium shifts in favor of conversion of bicarbonate to CO2.

H2O +CO2 H2CO3 HCO3- + H+

Fig. 42.29

Fig. 42.29, continued

• When an air-breathing animal swims underwater, it..can’t breath

• Most humans can only hold their breath for ?

• Seals and cetaceans (whales) ??

Free Diving

Little fish are tasty

• An adaptation of these deep-divers, such as the Weddell seal, is an ability to store large amounts of O2 in the tissues.

• Compared to a human, a seal can store about twice as much O2 per kilogram of body weight, mostly in the blood and muscles.

• MYOGLOBIN

• About 36% of our total O2 is in our lungs and 51% in our blood.

• In contrast, the Weddell seal holds only about 5% of its O2 in its small lungs and stockpiles 70% in the blood.

• What organ would be HUGE in the seal compared to us?

• What do you think a training adaptation is related to this?

• Adaptations of deep sea divers.

• First, the seal has about twice the volume of blood per kilogram of body weight as a human.

• Second, the seal can store a large quantity of oxygenated blood in its huge spleen, releasing this blood after the dive begins.

• Third, diving mammals have a high concentration of an oxygen-storing protein called myoglobin in their muscles.

• This enables a Weddell seal to store about 25% of its O2 in muscle, compared to only 13% in humans.

Questions

• What is a pneumothorax- why bad, how fix??

• What is pericarditis- why bad, how fix?