{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

ch01.5 - Language of Anatomy

ch01.5 - Language of Anatomy - Chapter 1 The Human Body An...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
The control center, which determines the level (set point) at which a variable is to be main- tained, analyzes the information it receives and then determines the appropriate response or course of action. The third component is the effector, which provides the means for the control center’s re- sponse (output) to the stimulus. Information flows from the control center to the effector along the efferent pathway . ( Efferent information exits from the control center.) The results of the response then feed back to influence the stimulus, either by depressing it (negative feedback) so that the whole control mechanism is shut off or by enhancing it (positive feedback) so that the reaction continues at an even faster rate. Most homeostatic control mechanisms are negative feedback mechanisms. In such sys- tems, the net effect of the response to the stimulus is to shut off the original stimulus or reduce its in- tensity. A frequently used example of a negative feedback system is a home heating system con- nected to a thermostat. In this situation, the ther- mostat contains both the receptor and the control center. If the thermostat is set at 20°C (68°F), the heating system (effector) will be triggered ON when the house temperature drops below that set- ting. As the furnace produces heat, the air is warmed. When the temperature reaches 20°C or slightly higher, the thermostat sends a signal to shut off the furnace. Your body “thermostat,” located in a part of your brain called the hypothalamus, oper- ates in a similar way to regulate body temperature. Other negative feedback mechanisms regulate heart rate, blood pressure, breathing rate, and blood levels of glucose, oxygen, carbon dioxide, and minerals. Because they tend to increase the original dis- turbance (stimulus) and to push the variable farther from its original value, positive feedback mechanisms are rare in the body. Typically these mechanisms control infrequent events that occur explosively and do not require continuous adjust- ments. Blood clotting and the birth of a baby are the most familiar examples of positive feedback mechanisms. Homeostatic Imbalance Homeostasis is so important that most dis- ease can be regarded as a result of its disturbance, a condition called homeostatic imbalance. As we age, our body organs become less efficient, and our internal conditions become less and less stable. These events place us at an increasing risk for ill- ness and produce the changes we associate with aging. Examples of homeostatic imbalance will be pro- vided throughout this book to enhance your under- standing of normal physiological mechanisms. These homeostatic imbalance sections are preceded by the symbol to alert you that an abnormal condition is being described. The Language of Anatomy Learning about the body is exciting, but our in- terest sometimes dwindles when we are con- fronted with the terminology of anatomy and physiology. Let’s face it. You can’t just pick up an anatomy and physiology book and read it as though it were a novel. Unfortunately, confusion
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern