Honors and AP Biology Homework Chapter 20: Tissues and Organ Systems
Textbook assignment: Chapter 20: Animal Structures, all sections.
Here we look at the common characteristics of all animals, concentrating on vertebrates and the human body in particular, and occasionally comparing these with invertebrate structures that perform similar functions.
- 20.1-2: We organize animal structures from simple to complex: cells make up tissues, different tissues form organs, multiple organs in an organ system support a common metabolic function, and together these make up a viable organism. The ability of the organ systems to work together and deliver nutrients and gases, and remove wastes, helps determine the size of the organism.
Note: While biologists use the term "design" to identify the arrangement of organ parts and their interrelationships in systems, Christianity, Islam, Judaism, and other religions use the term in the context of creation and biological species to describe a deliberate action of the divine mind. It is important to remember that from a purely scientific point of view (at least, the way science is currently practiced), natural selection is not a deliberate process and does not follow some mandate to "make things better". For example, a biologist would not say that lungs evolved because we need oxygen to breathe; rather, those animals with lung-like organs were able to better survive and reproduce than those without.
One point to keep in mind is that form and function are not separate, except insofar as we think about them. In organisms, the form of a cell, an organ, or a system, helps determine the limits of its function, but the function often also supplies the features of the form.
- 20.3-7: Tissues are connected or interacting sets of cells. There are four tissue types commonly found in animals:
- Epithelial tissue provides surface coverings (skin, mucous membranes, intestinal lining).
- Connective tissue provides support or transport (bones, blood, fat storage)
- Muscle tissue provides movement (muscles)
- Nerve tissue allows the body to control and communicate between systems (brain, central and peripheral nervous system, sensory organs).
There are other structures besides cells that make up animal tissues. These include collagen fibers, fat globules, and lymph solutions.
- 20.8: Tissues in different systems are organized in layers to perform their specialized functions.
- 20.9: Understanding cell differentiation allows bioengineers to produce designer tissues that can be used to transplant artificially-grown functioning organs into individuals with damaged organ systems, using the individual's own cells to avoid immune-system rejections common when organs are sourced from another individual.
- 20.10: The different organ systems do communicate with one another, providing information feedback that allows the body to regulate processes and keep the body state "normal". Sometime this communication involves nerve signals; sometimes it involves transmission of hormones to interact with chemicals on the surface or inside the cell.
20.11: As an example of a membrane, skin facilitates transmission of nutrients and wastes, but also offers protection to the tissues within the organism
- 20.12: New techniques allow us to investigate the actual functions of these systems without invasive or destructive results. But studies must be well designed to exclude factors that may affect results, and to prevent researchers or participants from skewing the results by seeing only what they want to see.
20.13: Most systems support exchange of materials, such as gasses, liquids, and solids that the body needs, across membrane interfaces. The exchange can bring in nutrients or export wastes.
20.14: For a body to function safely and most efficiently, it must maintain temperature and concentrations of nutrients and wastes within certain limits. Maintaining homeostasis requires constant monitoring by the nervous system.
20.15: Many situations that could lead to an imbalance are self-correcting: a function that produces some product may itself be turned off by an excess of the product (negative feedback).
Read the following weblecture before chat: Unifying Concepts of Animal Structure and Function
Take notes on any questions you have, and be prepared to discuss the lecture in chat.
Perform the study activity below:
Tissue studies and genetics come together when biologists study the origins of Alzheimer's disease and propose treatments and prevention.
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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