Study Guide for Chapter 40

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University of Toronto Scarborough
Biological Sciences
Mary Olaveson

Chapter 40 Physiology, Homeostasis and Temperature Regulation Internal Environment- cells of multicellular animals exist within an internal environment of extra cellular fluid that bathes every cell of the body. - Some cells evolved to be the interface between the internal and the external environments and to provide the necessary transport functions to get nutrients in, move wastes out, and maintain appropriate iron concentrations in the internal environment. - Other cells became specialized to provide internal; functions such as circulation of the extra cellular fluids, energy storage, movement, and information processing. Homeostasis- the maintenance of stable conditions (within narrow range) in the internal Environment - The condition of regulating the internal environment with the affects of the external environment - Maintaining equilibrium - To avoid homeostasis, physiological systems must be controlled and regulated in response to changes in both the external and internal environments. Effectors- effects the changes in the internal environment. -Effectors are controlled systems because their activities are controlled by commands from regulatory systems. Regulatory Systems-in contrast, obtains, process and integrate information, then issue commands to controlled systems. Sensor- provides the feedback information that is compared to the internal set Point (reference point) Negative feedback- the most common use of sensory information in regulatory systems. - The word negative indicated that this feedback information causes the effectors to reduce or reverse the process or counteract the influence that created an error signal. Positive feedback- rather than returning a system to a set point, positive feedback amplifies a response. Ex urination, defecation, sneezing and vomiting Feed forward information- is to change the set point. Ex seeing a deer up ahead while you are driving which makes you change your set point to a lower speed. Tissue- is an assemblage of cells, and although there are many, many types of cells, there are only four kinds of tissue: 1)Epithelial tissue- are sheets of densely packed, tightly connected epithelial cells that cover inner and outer body surfaces - Act as barriers and provide transport across those barriers. - Some cells secrete hormones, milk, mucus, digestive enzymes or sweat
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