RESPIRATION copy - RESPIRATION Basic Principles(4 1...

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RESPIRATION Basic Principles (4): 1. Increase capacity for gas exchange respiratory surfaces greatly expanded through microscopic subdivisions of membrane 2. Increase diffusion rates membrane across which gases pass = very thin 3. Facilitate passage membranes must be moist 4. Provide adequate concentration of oxygen for uptake/assist removal of CO 2 from membrane medium (air, water) containing the oxygen must be constantly replenished or moved through system Respiration Functions: All cells, tissues, organs require nutrients/oxygen to survive – necessary mechanism to rid cells of metabolic byproducts Respiratory system = responsible for delivering to and removing gases from a site where they can come in contact with the circulatory system o Movement of respiratory gasses (oxygen, CO 2 ) between respiratory and circulatory surfaces Simple passive diffusion – gas moves from higher concentration site through permeable membrane to lower concentration site Movement = down concentration gradient, continues until gas concentration at equilibrium Not sole mechanism of vertebrates Problem: too slow to meet needs of multicellular – takes too long for oxygen to diffuse a cm of tissue for use o Small organisms rely on simple diffusion for gas exchange, large need more extensive structures/mechanism to get oxygen to circulatory/ remove CO 2 o Vertebrates = respiratory membrane very large, tightly packed, thin/moist, associated pumping mechanisms to move medium (air, water) through or in/out of respiratory structure Pumping apparatus – important for terrestrial vertebrates (respiratory internal – protection/avoid desiccation) Ventilation = move air through or in/out of lungs (placed within thoracic cavity) o Aquatic – use gills Differences in partial pressure of each gas in blood and respiratory medium = driving force of gas exchange (medium across surface into blood back again) Partial pressure = pressure that a gas exerts of a system o Air (mix of different gases) – nitrogen (79%), oxygen (20.95%) Aquatic Respiration: Constraints of life in water (2)
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o 1. Oxygen isn’t abundant Quality dissolved in water depends on partial pressure of air o 2. Water in which oxygen is dissolved – much denser, more viscous than air o Fish adaptation – large respiratory surface, move larger volume of water across it at considerable energetic expense Respiratory membrane close proximity to water easy CO 2 unloading (highly soluble in H 2 O) o Problems: heat loss (fish maintain body temp. of surrounding water), water, salt, nitrogenous waste also diffuse through membrane – loss/gain of water/salt from water can upset body fluid osmotic concentration Gills = primary respiratory structure of aquatic vertebrates o Internal gill structures: Primary Gill Lamellae (adult fish) – internal gills consisting of many vascularized plates attached to gill/brachial pouch walls
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RESPIRATION copy - RESPIRATION Basic Principles(4 1...

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