Week 8 Notes
Popular in Fundamentals of Biology II: Ecology and E
Popular in Biology
This 5 page Class Notes was uploaded by Chasia Notetaker on Saturday March 26, 2016. The Class Notes belongs to BIOL 12000 at Ithaca College taught by Nancy L Jacobson in Fall 2016. Since its upload, it has received 9 views. For similar materials see Fundamentals of Biology II: Ecology and E in Biology at Ithaca College.
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Date Created: 03/26/16
Transitional forms are not just found in fossils but in living species in the evolution of the lungs in the evolution of the heart Respiration Organs of gas exchange (O 2n, CO2out) 1. Gillswater a. All fish b. Amphibians immatures as well as a few adult salamanders 2. Lungsair a. Primitive ray finned fish b. Lungfish i. Supplement gills in oxygen poor water c. Most amphibian adults d. All reptiles (including birds) and mammals 3. Thin skinwater a. Many amphibians b. 100% of gas exchange in a few Gills most are very efficient at extracting dissolved O2from water extract 8090% water has less oxygen than air use countercurrent flow blood (in capillaries) flows in opposite direction to the water (over gills) oxygen concentration is always higher in the water than in the blood diffusion occurs along entire length of gas exchange surface Lungs lungs are internally moistened sacs used for gas exchange, highly vascularized allows gas exchange with air (gills wouldn’t work, they would dry out and stick together) lungs evolved from evagination of the gut lungs are lined by endoderm you can choke if food goes down your trachea instead of your esophagus in ray finned fish, lungs evolved into the swim bladder (used for buoyancy) primitive ray finned fish can still use it as lungs swim bladder in the rest of the ray finned fish get gas from blood so it can no longer act as the lungs lung fish use lungs solely as lungs supplement gills in low oxygen water can breathe air if ponds dry out most tetrapod adults rely entirely on lungs lungs became more and more finely divided mammals have alveoli the lungs of birds are different have air sacs attached which allow one way flow through the lungs into nares > trachea > bronchi > posterior air sacs > lungs > anterior air sacs > bronchi > trachea > out nares no gas exchange in air sacs bird lungs are very efficient at extracting oxygen from the air similar to countercurrent flow across gills Ventilation of lungs Inhalation lungs are internal, so gases must be actively inhaled, this can happen 2 ways fish with lungs and amphibians use positive pressure gulp air, contract, force air into lungs reptiles and mammals use negative pressure (allows for larger lungs) all use intercostal rib muscles to expand rib cage mammals also use a diaphragm Circulation circulatory system takes oxygen to the tissues, removes CO 2from the tissues takes nutrients to the tissues and removes waste from the tissues Evolution of circulatory system in most fish 2 chambered heart (atrium and ventricle) single circulation (heart > gills > body > heart) blood going to the body is highly oxygenated but is slowed by resistance in gill capillaries when a fish swims it helps move the blood through its body in lungfish 2 chambered heart with a partial septum in the atrium (and small partial septum in ventricle) single circulation (when only using gills) double circulation (when breathing air) pulmonary ( heart > gills and lungs > heart) systemic ( heart > skips gills > body > heart) stronger flow to the body, but some mixing of oxygenated and deoxygenated blood spiral valve separates deoxygenated and oxygenated blood to some extent in amphibians 3 chambered heart 2 atria and 1 ventricle double circulation pulmocutaneous and systemic circuits important for animals that live on land, need more pressure to move the blood some mixing of oxygenated and deoxygenated blood in the ventricle can shut off pulmonary artery when under water; cutaneous artery > skin capillaries where gas exchange occurs through the skin in most reptiles 3 chambered heart with a partial septum in the ventricle double circulation less mixing of oxygenated and deoxygenated blood in the ventricle in crocodilians, birds, and in mammals 4 chambered hearts (2 atria, 2 ventricles) double circulation oxygenated and deoxygenated blood is kept completely separate efficient respiration and circulation allows endothermy (“heat from within”) to evolve in birds and mammals generate through high metabolism need to eat a lot need to transport lots of oxygen to their cells (for aerobic cellular respiration) can remain active even in cold temperatures fish are most efficient at breathing, in water birds have a crosscurrent system, less efficient than fish but more efficient than other tetrapods no residual volume cross current flow of blood and air in birds exchange of oxygen in alveoli of mammals Animal behavior foraging Feedinghave to find, recognize, capture, eat, and digest food Foragingfood obtaining behavior including all of the above except digestion animals often find and recognize find efficiently using a search image Optimal foraging theory feeding behavior should be efficient maximum energy obtained minimize energy expended and risk of predation when we were hunters and gatherers sweet taste associated with fruit vitamins fats were high in calories which was good at the time individually, we can now get many more calories than we expend, we are too efficient those people actually getting our food for us are often too efficient as well fish are caught faster than they can reproduce Generalists versus Specialists Generalists eat many types of food vs. eating few actually a continuum they can live anywhere there is acceptable food Specialists can eat (or find) food that most other can’t ex. Koalas only eat eucalyptus leaves if food source is scarce then you are too many herbivores have an enlarged cecum with cellulosedigesting bacteria and protists ways to divide food resources territories defended area foraging is one reason for setting up a territory exclusive access to food for self and offspring familiarities with area helps forage efficiently and or avoid predators others, usually of the same species, are kept out song in birds urine scenting in some mammals sometimes physical attacks ”pecking order” alpha male or female is at the top in social groups , a dominance hierarchy can determine who can has access to the food first who gets the best food so in times of scarcity, the more dominant individuals survive
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