Presentation on theme: "Biology Main points/Questions"— Presentation transcript:
1 Biology 103 - Main points/Questions How do your lungs work?How do gasses get to your cells?What gasses do plant cells need to transport?
2 Remember Circulation … Plants and animals push extracellular fluidsPlants generate flow w/o muscle tissueAnimals generate flow with pumping musclesFungi move intracellular fluidsUse cytoplasmic streamingProteins in the cell “stir” the cytoplasm moving nutrients etc. to rapidly growing hyphae.Protists use diffusion & streaming
3 Why exchange gases? Cellular respiration - summarized as: Glucose + oxygen carbon dioxide + waterLook! This consumes oxygen and gives off CO2And, of course, produces ATP!So - Gas exchange supplies oxygen for cellular respiration and disposes of carbon dioxide
4 Gas ExchangeAll the complex multicellular critters use oxygen to produce ATP in mitochondriaSo all cells need gas exchange for thisMany plant cells also need a supply of carbon dioxide for photosynthesisWe look at animals first
5 In vertebrates gases are transferred via the circulatory system! Gas exchange occurs between an organism and the environment, often in specialized respiratory organs.In vertebrates gases are transferred via the circulatory system!Figure: 35-1Title:Skeletal muscle structureCaption:A muscle is surrounded by connective tissue and attached to bones by tendons. It contains from a few to 1000 muscle cells called muscle fibers, often packaged into bundles within the muscle. Each fiber is packed with cylindrical subunits called myofibrils, which contain thick and thin filaments of protein.
6 Ultimately exchange happens between cells and the interstitial fluid that surrounds them! Figure: 35-1Title:Skeletal muscle structureCaption:A muscle is surrounded by connective tissue and attached to bones by tendons. It contains from a few to 1000 muscle cells called muscle fibers, often packaged into bundles within the muscle. Each fiber is packed with cylindrical subunits called myofibrils, which contain thick and thin filaments of protein.
7 Types of Respiratory Systems The simplest animals obtain oxygen directly from their environments through diffusion
8 Fig. 40-3MouthDiffusion works well as long as distances are small and surfaces are permeableGastrovascularcavityBut as organisms become more complex they need specialized exchange organsExchangeExchangeExchangeFigure 40.3 Contact with the environment1.5 mm(a) Single cellCnidarians
9 All organisms use diffusion at the cellular level but… Fig. 40-3MouthDiffusion works well as long as distances are small and surfaces are permeableGastrovascularcavityAll organisms use diffusion at the cellular level but…ExchangeExchangeExchangeFigure 40.3 Contact with the environment1.5 mm(a) Single cellCnidarians
10 Types of Respiratory Systems As organisms get more complex they need specialized organs to exchange gases with the environmentdifferent phyla have different organs:Gills in fish, some arthropods, mollusks,Tracheae in insects,and lungs mostly in terrestrial chordates
11 Why do gases move?Gases diffuse down pressure gradients in the lungs and other organsIn the lungs and tissues, O2 and CO2 diffuse from where their concentrations are higher to where they are lower
12 Remember diffusion Movement from high concentration to low Doesn’t require any energy expenditure to make happenWorks very quickly over short distancesImportant transport mechanism of cellular material
13 Factors controlling diffusion rate: Can you remember what some are?
14 Factors controlling diffusion rate: TemperatureSize of molecule:Concentration gradient:Surface area:Distance:Mediumset by organismsetconstantly maintainedIncreased as much as possibleDecrease as much as possibleGas as often as possible
15 Respiratory MediumAnimals can use air or water as a source of O2, or respiratory mediumIn a given volume, there is less O2 available in water than in airObtaining O2 from water requires greater efficiency than air breathing
16 Respiration in Aquatic Vertebrates Water moves past a fish’s gills in one directionthis permits countercurrent flow
17 Respiration in Aquatic Vertebrates Countercurrent flowextremely efficient way of extracting oxygenblood flows through a gill filament in an opposite direction to the movement of waterthe blood always encounters water with a higher oxygen concentration (constant gradient for diffusion)
18 Figure 30.3 Countercurrent flow Because the two fluids flow in opposite directions blood can continue to pick up oxygen well past the 50% mark.Figure 30.3 Countercurrent flow
19 Figure 30.3 Countercurrent flow If blood flowed in the same direction as water the system could exchange at most 50% of the gas dissolved.Figure 30.3 Countercurrent flow
20 Terrestrial gas exchange For organisms on the land gas exchange poses a new problemThe exchange must happen on living cells bathed in fluid – but fluid loss can be a huge problem so…Gas exchange organs are moved into the body & adaptations to prevent water loss are common.
21 Tracheal Systems in Insects The tracheal system of insects consists of tiny branching tubes that penetrate the bodyThe tracheal tubes supply O2 directly to body cells
23 Lungs Lungs - an infolding of the body surface The circulatory system transports gases between the lungs and the bodyThe size and complexity of lungs correlate with an animal’s metabolic rate
24 In humans: A system of branching ducts conveys air to the lungs Air inhaled through the nostrils passes through the pharynx via the larynx, trachea, bronchi, bronchioles, and alveoli, where gas exchange occursExhaled air passes over the vocal cords and can create sounds
29 Blood arriving in the lungs has a low amount of O2 and a high concentration of CO2 relative to air in the alveoliIn the alveoli, O2 diffuses into the blood and CO2 diffuses into the airIn tissue capillaries, gradients favor diffusion of O2 into the interstitial fluids and CO2 into the blood
30 When it leaves this has reversed AlveolusAlveolusPCO2 = 40 mm HgPO2 = 100 mm HgPCO2 = 46PO2 = 40PCO2 = 40PO2 = 100Blood arriving in the lungs has a low O2 and a high CO2 relative to air in the alveoliWhen it leaves this has reversedThen in body tissue the situation is the oppositeCirculatorysystemCirculatorysystemPO2 = 40PO2 = 100PCO2 = 46PCO2 = 40Figure Loading and unloading of respiratory gasesPO2 ≤ 40 mm HgPCO2 ≥ 46 mm HgBody tissueBody tissue(a) Oxygen(b) Carbon dioxide
31 To move more gas they are carried in several ways AlveolusAlveolusPO2 = 100 mm HgPCO2 = 40 mm HgPO2 = 40PO2 = 100PCO2 = 46PCO2 = 40CirculatorysystemCirculatorysystemPO2 = 40PO2 = 100PCO2 = 46PCO2 = 40PO2 ≤ 40 mm HgPCO2 ≥ 46 mm HgBody tissueBody tissueIn tissue capillaries, O2 moves out of the blood and CO2 moves into the blood… why?To move more gas they are carried in several waysFigure Loading and unloading of respiratory gases
32 hemoglobin molecules contain iron - oxygen binds in a reversible way Figure 30.8 The hemoglobin molecule
33 hemoglobin acts like little sponges for oxygen at high O2 levels (like in the lungs), most hemoglobin carry a full load of O2in the tissues, the O2 levels are much lower and hemoglobin gives up its bound oxygenThe vast majority (> 90%) of oxygen you use was carried to your cells on hemoglobin
34 CO2 must also be transported by the blood about 8% simply dissolves in the plasma20% is bound to hemoglobinrest is carried as HCO3- in blood cells & plasmaThis is highlighted on figure from your book…
36 What about plants? Do they transport gasses in circulatory system? No! – they rely only on diffusionspecialized anatomy makes this work…CO2O2LightH2OSugarFigure 36.2 An overview of resource acquisition and transport in a vascular plantO2H2O and mineralsCO2
37 Leaf cross section shows… Cells packed in top layer - photosynthesisOpen “spongy” layer below for exchangeBut cuticle blocks gas exchange…
38 Lots of open spaces inside but… Plant leaf anatomy:Lots of open spaces inside but…Must open stomata (pores) to get gasses inOpenedClosed
39 This causes leaf to lose water so… plants need to balance water loss and gas exchangeGuard cells control opening/closingHow…?changes in the water pressure of guard cells
40 When the guard cells lose water, the stoma closes Figure guard cells open and close stomataWhen the guard cells are plump and swollen with water, they are said to be turgid and the stoma is openWhen the guard cells lose water, the stoma closes
41 Controlling stomata opening: Most plants keep closed at night open during the day. Why?Some specially adapted plants keep closed during day & open at night… Why would you do that?Hint: ➔
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