Dr. O'Quin Notes 4/11, 4/13, 4/15
Dr. O'Quin Notes 4/11, 4/13, 4/15 Bio 152
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This 11 page Class Notes was uploaded by Alena Comley on Friday April 15, 2016. The Class Notes belongs to Bio 152 at University of Kentucky taught by Dr. O'Quin in Spring 2016. Since its upload, it has received 11 views. For similar materials see Introductory Biology II in Biology at University of Kentucky.
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Date Created: 04/15/16
Chapter 45 Gas Exchange and Circulation Remember that during cellular respiration, oxygen is consumed and carbon dioxide is produced o These gases need a way to be brought in and let out Gas exchange involves a four step process o In ventilation, the movement of air or water through a specialized gas exchange organ occurs o During gas exchange the diffusion of O and CO between air and 2 2 water and the blood at the respiratory surface occurs o Circulation involves the transport of dissolved O and2CO throu2hout the body via the circulatory system o Cellular respiration occurs, where the cells use O and 2roduces CO 2 CLICKER #1 Which step of gas exchange involves the transport of oxygen and carbon dioxide throughout the body? A Ventilation B Gas Exchange C Circulation D Cellular Respiration ANSWER: C Gas Exchange Steps 1 and 2 are accomplished by the respiratory system- a collection of cells, tissues, and organs responsible for gas exchange between the individual and the environment Step 3 occurs via a circulatory system, which in many cases involves a muscular heart that propels a specialized, liquid transport tissue throughout the body via a system of vessel How the 2 major respiratory gases, O and2CO behav2 in air and water When talking about gases in the air, we consider what is known as the partial pressure Partial pressure has two component: o The percent of that particular gas in the atmosphere o The total atmospheric pressure (of all gases) at a particular altitude Here you can see that for the respiratory gases, O is 2t about 21% in the atmosphere and CO is a2 0.03% You can see that at sea level, the PO 2s about 160 mm Hg, but that would change at the different altitude levels CLICKER #2 If the percent of oxygen is 21%, what is the partial pressure at atmospheric pressure of 550 mm Hg? A 11.5 mm Hg B 160 mm Hg C 55 mm Hg D 115.5 mm Hg ANSWER: D The concept of partial pressure is important for gas exchange because gases move from regions of high partial pressure to regions of low partial pressure The reason it is so hard to breath at higher altitudes is because the difference in partial pressure of the lungs and atmosphere is greatly reduced Respiratory Gases O 2nd CO d2ffuse into water from the atmosphere, but exactly how much depends on several factors o Solubility in water: oxygen has a very low solubility in water, which is why our blood contains molecules that will tightly bind it o Water temperature: increase temperature = decrease in dissolved gases (decreased solubility) Warm habitats have less oxygen available than cold habitats o Presence of other solutes: seawater can hold less dissolved gases because more solutes are more present than freshwater o Partial pressure of the gas in contact with water: if the partial pressure of the gas in the liquid exceeds that in the adjacent gas, the gas will bubble up and out of the liquid Newly opened bottle of soda, CO bub2les out because partial pressure of gas in atmosphere is lower, so it moves from high to low partial pressure CLICKER #3 Which type of water should have lowest rates of dissolved oxygen? A Warm, saltwater B Warm, fresh water C Cold, saltwater D Cold, freshwater ANSWER: A Oxygen in aquatic habitats The partial pressure of oxygen varies in different type of aquatic habitats due to different factors (in addition to ones we just talked about Lots of photosynthetic organism = more oxygen Stagnant water = low oxygen due to surface level decomposers using it Water near the surface = higher oxygen Deeper water = less oxygen Rapids, waterfalls, and other types of whitewater are the most highly oxygenated of all aquatic environments (due to increased surface area Dissolved oxygen depletion is the most common cause of fish kills Dead zones are areas of water with little to no dissolved oxygen present Some small organisms that live in wet, humid habitats can perform respirations across the body surface However, large animals or those that live in dry habitats need some sort of specialized respiratory organ FICK'S Law Of Diffusion states that the rate of diffusion of a gas depends on five paramenters o Solubility of the gas in the aqueous film lining the exchange surface (k) o Temperature (k) o The surface area available for diffusion (A) o The difference in partial pressures of the gas across the gas exchange surface (P -2 )1 o The thickness of the barrier to diffusion (D) CLICKER #1 What component of the equation would you expect natural selection not to act on? A K B A C P2-P1 D D ANSWER: A- K Gases will diffuse at the highest rates when three conditions are met: oA is large- meaning a large surface area is available for gas exchange If the epithelium of the human lung were spread flat, it would cover about the size of a tennis court oD is small- the respiratory surface is extremely thin In the human lung, barrier diffusion is a single cell thick oP 2P 1s large- meaning the partial pressure gradient of the gas across the surface is large This is maintained by an efficient circulatory system that sits right next to the respiratory surfaces CLICKER #2 Which component of the equation do we want to keep small? A K B A C P2-P1 D D ANSWER: D- D Respiratory Systems Gills- outgrowths of the body surface or throat and are used for gas exchange in aquatic animals In some invertebrates, gills project from the body and are in direct contact with the water In other invertebrates, gills are located inside the exoskeleton of the body wall, with water having to be driven over them Fish gills are located in both sides of the head and in the teleost fishes, consists of four arches In most fishes, the opening and closing of the mouth and operculum will pump water over the gills Some fish swim so fast, they are able to force water through their gills by simply swimming with their mouths open CLICKER #3 How do fish ventilate their gills? A Opening and closing of the mouth B Opening and closing of operculum C Swimming with an open mouth D All of the above ANSWER: D- All of the above As water flows over the gills, it passes over gill filaments, which contain gill lamellae o Surface area for gas exchange is increased Capillaries run through each lamella Fish utilize a countercurrent exchanger to maximize oxygen exchange from the water into the gills o As a result, a slight gradient in partial pressure of oxygen exists along the entire lamella CLICKER #1 What part of the insect are like plant stomata? A Cuticle B Spiracle C Tracheae D Eyes ANSWER: B- Spiracle Insect Respiration Insects have air-filled tubes called tracheae, with openings of these tubes to the outside called spiracles The ends of these tracheae are tiny and highly branched This allows transport of air to where gas exchange can take place directly across the plasma membrane While very small insects can ventilate the tracheae by diffusion, large insects must actively ventilate their tracheal system How is this accomplished? Ventilation occurs via the compression and dilation of the tracheae by muscles when they contract and relax When muscles relax, the volume of the tracheal system increases and air rushes in When muscles contract, the volume of the tracheal system decreases and air moves out In the largest insects, the movement of gases is further promoted by larger tracheae diameters o This increases the area for gas exchange Why don’t we see larger insects today? Respiratory Organs In terrestrial vertebrates, the respiratory system includes the trachea, bronchi, bronchioles, and the lungs In the lungs of mammals, the lungs are finely divided into sacs called alveoli, which are where the gas exchange actually occurs These alveoli help to increase the total surface area for gas exchange This is in contrast to frogs and other amphibians, in which the lungs are a simple sac lined with blood vessels CLICKER #2 What structure do mammalian lungs have that frogs don’t have? A Capillaries B Epithelium C Alveoli ANSWER: C- Alveoli Lung ventilation- the lungs can be ventilated in one of two ways: o Positive pressure ventilation Used by frogs and related animals Air is effectively pushed into their lungs o Negative pressure ventilation Used by humans and other mammals Air is pulled into the lungs When you inhale, the diaphragm contracts and moves down and the muscle between the ribs contract This increases the volume of the chest cavity, which in turn lowers the pressure As a result, air flows in via a pressure gradient You can demonstrate this on your own using a simple setup CLICKER #3 An increase in chest volume causes a _________ in pressure. A Increase B Decrease C Constancy ANSWER: B- Decrease Dead space- occupied by about 1/3 of the volume of each breath; air passages that aren't lined by a respiratory surface o Dead space = tubes that conduct the air Bird Respiration Flight is an energetically demanding activity Birds can fly at high elevations where the partial pressures of oxygen is low o How do they obtain enough oxygen for these activities?? o Bar headed geese fly at altitudes as high as Mt. Everest. Birds are unique because they have unidirectional airflow in their lungs o During inhalation, air flows through the trachea and enters the two large air sacs posterior to the lungs o During exhalation, air leaves the posterior air sacs and enters the parabronchi in the posterior portion of the lungs o During the next inhalation, air moves into the parabronchi in the anterior lungs and into the anterior air sacs o During the next exhalation, air moves out of the anterior sacs, through the trachea, and out to the atmosphere So why is the avian respiratory system considered more efficient than ours? 1. They have less dead space 2. Gas exchange occurs during both inhalation and exhalation (only occurs in inhalation in human) 3. Blood circulated through bird lungs in a cross current pattern
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