8) Gas Exchange
Terms in this set (21)
connection btw cellular respiration, gas exchange, and circulation
...cellular respiration needs oxygen, produces CO2 as a byproduct
the features of a gas exchange surface
...thin, large SA, moist, usually contact with circulatory systems, living cells simple animals- body surface is a gas exchange surface
how do gills take advantage of countercurrent flow?
...provide efficient gas exchange in water (harder in water because much less O2 than air, O2 diffuses much slower, water is more dense and viscous than air), one way flow of respiratory medium (one way flow of blood, but opposite the flow of water), water flows from high to low PO2, blood flows from low to high PO2
why don't insects need blood vessels to circulate gases?
tracheal system= extensively branched system of internal tubules . adapted for gas exchange in terrestrial environments. brings outside environ close enough to nearly every cell to diffuse! (no direct contact with blood vessels needed!)-insects, centipedes, millipedes, some spiders......
how are lungs adapted for exchange in a terrestrial environment?
infoldings of throat. cluster of alveoli (air sacs)= site of gas exchange. vertebrates: mammals, birds, reptiles, amphibians...
exchange of gases between an alveolus and a capillary
inhaled oxygen moves from the alveoli to the blood in the capillaries, CO2 moves from the blood in the capillaries to the air in the alveoli....External (pulmonary) respiration- Exchange of gases between the alveoli of the lungs and the blood in pulmonary capillaries across the respiratory membrane. During this, pulmonary capillary blood gains O2 and loses CO2 .
exchange of gases btw an actively metabolizing cell and a capillary
Internal (tissue) respiration- Exchange of gases between blood in systemic capillaries and tissue cells. Inthis step the blood loses O2 and gains CO2. Within cells, the metabolic reactions that consume O2 and give off CO2 during the production of ATP are termed cellular respiration..
how does the contraction of the diaphragm power human inhalation?
the diaphragm contracts, chest expands, the lungs are pulled outward, and alveolar pressure decreases exhalation: the diaphragm relaxes, the lungs recoil inward, and aveolar pressure increases forcing air out of the lungs. Air moves into the lungs when alveolar pressure is less than atmospheric pressure, and out of the lungs when alveolar pressure is greater than atmospheric pressure.negative pressure- pull air into lungs
why is gas exchange not entirely efficient?
1) tidal exchange- type of exchange observ. in humans (not entirely efficient)-2 way airflow (same path in and out)-gas exchange does not occur across the entire respiratory surface 2) residual volume-observed in organisms with lungs...
gas exchange surfaces of fish
gills, counter-current exchange. one way flow of blood, but in opp direction of water. blood vessels are directly in contact with body surface...
gas exchange surfaces of birds
parabronchi. types of exchange surfaces observed in bird's lungs.-Inhale: Air sacs fill with O2 rich air
-Exhale: Air sacs empty into lungs
-Very efficient form of extracting O2 from air Type of exchange observed in birds-- cross-current exchange:
-Air flow is opposite of blood flow
-Gas exchange along the entire respiratory surface
gas exchange surfaces of mammals
gas exchange takes place in the aveoli. huge surface area. surfactin keeps the thin alveoli walls from collapsing
Type of exchange provided by Gills, maximizing the amount of O2 obtained in H2O
-One way flow of respiratory medium
-One way flow of blood, but in opp. direction of water.
Type of exchange observed in birds
-Air flow is opposite of blood flow
-Gas exchange along the entire respiratory surface..
Type of exchange observed in humans (not entirely efficient)
-2 way air flow/same path in and out
-gas exchange does not occur across entire respiratory surface..
how does negative feedback control breathing in humans?
Homeostatic Control of Breathing
Must maintain partial pressures of O2 and CO2
in narrow range, even during exercise. at rest: medulla respiratory center. during exercise: muscle cells-cellular respiration. O2 in blood decreased, CO2 increased. CO2 reacts with H2O which leads to a drop in PH, so increase breathing rate- normal CO2 and O2 levels restored
path of an oxygen molecule from your gas exchange surface to your big toe
Inhaled oxygen —> alveoli in lungs (surrounded by capillaries)
Oxygen is diffused into capillaries
In the capillaries, oxygen attaches onto hemoglobin in red blood cells
Heart pumps oxygenated blood throughout the body
Once the blood reaches where it has to go, the oxygen in the hemoglobin unloads --> deoxygenated blood then goes back up through your veins --> back to your heart -->cycle starts all over again
path of a CO2 molecule from your big toe to the gas exchange surface
Body tissue --> Interstitial fluid --> plasma within capillary --> Carbon Dioxide reacts with water to form Bicarbonate --> gets transported to lungs --> loses water --> diffuses out of the cell --> plasma within lung capillary --> alveoli
the role of hemoglobin in oxygen transport
-O2 binds to HB reversible (O2 loaded/O2 unloaded)
-HB binds cooperatively with O2. Each HB carriers 4 O2 molecules, so O2 binds one subunit and the other 3 readily unload 02 (process happens very quickly)
the ways in which CO2 is transported
1) 7% is dissolved in plasma
-Rest of C02 goes into RBCs
2) 23% goes into hemoglobin
3) 70% goes to make bicarbonate
how do smoking, genetic diseases, medical conditions assault the cardiovascular system?
negative effects of smoking: Destroys cilia (cleansing system) which line respiratory tract, causes emphysema
emphysema: Makes alveoli brittle (not elasticity) and reduces gas exchange surface because of cells dying
-Can lead to heart disease due to lack of good gas exchange to heart
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