Biology Homework Chapter 22: Gas Exchange
Textbook assignment: Chapter 22: Respiration, all sections.
Pay attention to the physiological processes here. You get to put into practice concepts of diffusion across the membrane that we introduced back in chapters 4 and 5. If you don't remember what happens during osmosis, facilitated transport or active transport, you should review those concepts carefully in section 22.1.
- 22.1 The body exchanges gases in a number of different situations. Air contains oxygen that diffuses across lung membranes into the circulatory system. Blood transports both oxygen to cells and carbon dioxide wastes away from cells. These gasses must be transported through circulatory system membranes and across cell membranes to reach the locations where they can be used by the cell or exhaled from the body altogether.
- 22.2 Gas exchange usually occurs across a moist surface found in one of four types of structures: the entire surface of the animal (earthworm), a specific external surface (fish gills), an internal surface exposed to the outside (insect trachea), or an enclosed internal surface (vertebrate lungs).
- 22.3 Gills have both an advantage (they don't have to be kept wet since they are in a wet environment) and a disadvantage (there isn't as much oxygen available as dissolved gas in water as there is in air). The countercurrent exchange method used by gill-bearing animals fosters a concentration differential in favor of the environment's oxygen, so that oxygen flows into the lungs along all parts of its path across the gill.
- 22.4 Tracheal systems found in insects allow the organism to draw oxygen directly from the air but are subject to water loss.
- 22.5 The theory of evolution assumes that life began in the oceans, so the study of lung structures is important as a source of information on how animal life may have moved from the sea to land.
- 22.6 Lung systems of terrestrial vertebrates are more complicated systems with passage from a nose to pharynx to larynx to trachea and bronchi, and finally to bronchioles and alveoli, where the gas exchange finally occurs. The chambers and tubes on the way to the alveoli keep the gases moist and filter out dirt and foreign organisms.
- 22.7 Smoking cigarettes irritate the cells lining the alveoli, coating them with chemicals that clog them up, and that can even cause DNA mutations leading to cancer.
- 22.8 Breathing is the muscular action that expands and contracts the lung cavity, force air into and out of the alveoli.
- 22.9 The breathing rate is controlled by the brain, which uses concentrations of CO2 in the blood to determine whether another breath is necessary.
- 22.10 In mammals, blood is the primary carrier of oxygen and carbon dioxide to and from the cells of the body, and each gas moves independently of the other, following its own concentration gradient.
- 22.11 Once in the blood, oxygen attaches itself to hemoglobin, which can absorb carbonic acid and act as a buffer to keep blood from reaching an unsafe acid level.
- 22.12 The mother's blood carries nutrients, gases, and pollutants to the fetus, making it imperative for the mother to use good health practices.
Read the following weblecture before chat: Respiration
Take notes on any questions you have, and be prepared to discuss the lecture in chat.
Perform the study activity below:
Chat Preparation Activities
- Essay question: The Moodle forum for the session will assign a specific study question for you to prepare for chat. You need to read this question and post your answer before chat starts for this session.
- Mastery Exercise: The Moodle Mastery exercise for the chapter will contain sections related to our chat topic. Try to complete these before the chat starts, so that you can ask questions.
- Required: Complete the Mastery Exercise with a score of 85% or better.
- Optional: Test yourself with the textbook multiple choice questions and note any that you miss that still don't make sense. Bring questions to chat!
- Go to the Moodle and take the quiz for this chapter.
Read through the lab for this week; bring questions to chat on any aspect of the lab, whether you intend not perform it or not. If you decide to perform the lab, be sure to submit your report by the posted due date.
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