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Lecture 9

BIO2242: Lecture 9 notes

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BIO2242 – LECTURE 9 Aerobic cellular respiration consumes oxygen and produces carbon dioxide: True False The primary role of RBC is to: Carry nutrients Repair cellular damage Localise respiratory enzymes Increase blood oxygen carrying capacity = do this with the help of hemoglobin Environmental oxygen is not constant in space or time: Cold water has more oxygen because its turbulent water, so it’s constantly mixed with air. As water warms up, it loses oxygen. Air pressure is lower at high altitude due to the weight of the air. Respiration in water: If the animal is big, they increase the SA so that there is a short distance between the cells and the environment. Respiratory organs increase diffuse SA: Animals with different body shapes need a special area devoted to increasing SA. Sea star = Invaginations of the coelom which makes up a large surface of the coelom that is directly exposed to the environment for gas exchange Marine worm = parapodia which have a large surface and a large supply of blood from the closed circulatory system Clam = Cnedia used for feeding and gas exchange Crayfish = another form of gill Gills are efficient in water but not air: Most animals that live in water and have a circulatory system have invaginations, so they increase the SA by branching. In fish, they have red gills because they are filled with blood and this blood is highly enriched with oxygen. Each of the lamella have a dense network of small capillaries. Gill ventilation: Water is hard to pass through the gills because it is very heavy. However, with the help of the mouth at the front and the operculum at the back, this is able to occur. They open their mouths to let water in, while the operculum is closed. Then, they close their mouths and open their operculum to draw water out from the cavity. They also raise the bottom of their mouth cavity. Gill area is proportional to activity level: Opercular pumping takes up energy. Ram ventilation: Ramming yourself through the water, and the water flows in. The main disadvantage of breathing water is: Its temperature Its oxygen concentration Its density = also important but not as important as the above Its taste Countercurrent flow: Whats important is the way water flows over the gills, and the way blood flows through the gills. Idea of maintaining a countercurrent flow is to maintain a conc. Gradient, which is relatively large. So it’s maximizing the conc. gradient in your blood (low) and conc. Gradient in the water (high). Respiration in air: Moist skin is important form of respiration. Gills are flimsy and tend to collapse so they are not efficient. Insects developed trachea, while mammals developed lungs. Tracheae: Tracheae is a system of tubes, which is very efficient in getting oxygen to every cell. You cannot ventilate them so they have a low transport capacity – you can get air, but once the air is in, you can't get them in and out very efficiently. The tracheole are directly at the end of the tracheae, contact directly with all the tissues in the body. The tracheole are filled with fliud, as oxygen eventually needs to go into a liquid environment so they don't dry out. Closing spira
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