Exam 1 Review:  Chapter 1:  Regulation Terms

hormones - Signal compounds produced by special glands which are released into the blood stream to be distributed throughout the body and which trigger responses in only those tissues that have specific receptor molecules which can bind and interact with the signal compound; sometimes referred to as "first messengers."

feedback system  = homeostatic feedback system - Any biological system which a regulated, modulated, controlled, or changed by the product, output, or response it produces; such systems consist of three general components:  receptors, control centers, and effectors; e.g., regulation of body temperature, blood glucose level, blood pH, etc.  (See Figure 1.4 in the text and below.)

stimulus - An agent, action, or condition that elicits or accelerates a physiological or psychological activity or response; a monitored change in the internal or external environment to which the body responds with appropriate behaviors or homeostatic control mechanisms; the trigger for a change in a homeostatic control mechanism.

receptor - 

1. Physiology. A specialized cell or group of nerve endings that responds to sensory stimuli.
2. Biochemistry. A molecular structure or site on the surface or interior of a cell that binds with substances such as hormones, antigens, drugs, or neurotransmitters

control center - A cell, tissue, or most commonly an organ (e.g., the brain, endocrine glands) which receives and interprets information about changes in the internal or external environment and generates homeostatic control signal information, stimuli (e.g., nerve impulses, hormones, local hormones) which trigger responses in target structures termed effectors.

effector - A muscle, gland, or organ capable of responding to a stimulus, e.g., transmitted by a nerve impulse or the arrival of a hormone or local hormone.

response - A bodily process occurring due to the effect of some foregoing stimulus or agent.

negative feedback - A response or homeostatic control mechanism which responds to a change in the internal environment with actions which restore the original dynamic equilibrium state. For example, producing sweat to cool an overheated body.

positive feedback - A response or homeostatic control mechanism which responds to a change in the internal environment with actions which change from the original dynamic equilibrium state. For example, the increase in the size of the placenta under hormonal control during pregnancy supports the nutritional needs of an ever-growing fetus.

disease -  A pathological condition of a part, organ, or system of an organism resulting from various causes, such as infection, genetic defect, or environmental stress, and characterized by an identifiable group of signs or symptoms.

List:

 4. two kinds of feedback systems.

          positive feedback control and negative feedback control

 5. the two most important body systems which regulate homeostasis.

         The nervous system and the endocrine system are most important (but all body systems have some role to play in regulation of homeostasis).

6.  three components of feedback systems.

        receptor - control center - effector

Describe:

1.   a negative and a positive homeostatic feedback system and explain how they differ.

Sketch and Label:

1. the components and flow of information in a homeostatic feedback system.