BIOL325 - Levels of Organization and Homeostasis Vocab

Physiology

the study of body functions

Anatomy

the study of body structure

Atoms

the basic unit of a chemical element

Molecules

the smallest unit of a pure substance that has the properties of that substance and is capable of a stable, independent existence

Cells

the smallest unit capable of carrying out the processes associated with life; the basic unit of both structure and function in living organisms

Plasma membrane

a microscopic membrane of lipids and proteins which forms the external boundary of the cytoplasm of a cell and regulates the passage of molecules in and out of the cytoplasm

Tissues

a functional aggregation of cells of a single specialized type, such as nerve cells forming nervous tissue

Muscle tissue

a functional grouping of cells specialized for contraction and force generation

Nervous tissue

a functional grouping of cells specialized for initiation and transmission of electrical signals

Epithelial tissue

a functional grouping of cells specialized in the exchange of materials between the cell and its environment; lines and covers various body surfaces and cavities and forms secretory glands

Connective tissue

tissue that serves to connect, support, and anchor various body parts; distinguished by relatively few cells dispersed within an abundance of extracellular material

Organ

a distinct structural unit composed of two or more times of primary tissue organized to perform one or more function; for example, the stomach

Body system

a collection of organs that perform related functions and interact to accomplish a common activity that is essential for survival of the whole body; for example, the digestive system

External environment

the environment surrounding the body

Internal environment

the body's aqueous extracellular environment, which consists of the plasma and interstitial fluid, and which must be homeostatically maintained for the cells to make life-sustaining exchanges with it

Intracellular fluid

the fluid collectively contained within all the body cells

Extracellular fluid

all the fluid outside the cells of the body; consists of interstitial fluid and plasma

Plasma

the liquid portion of the blood

Interstitial fluid

the portion of the extracellular fluid that surrounds and bathes all the body cells

Homeostasis

maintence by the highly coordinated, regulated actions of the body systems of relatively stable chemical and physical conditions in the internal fluid environment that bathes the body cells

Dynamic steady state

each homeostatically regulated factor being marked by continuous change that do not deviate far from a constant level

Homeostatic control system

a regulatory system that includes a sensor, integrator, and effectors that work together to bring about a corrective adjustment that opposes an original deviation from a normal set point

Negative feedback

a regulatory mechanism in which a change in a controlled variable triggers a response that opposes the change, thus maintaining a relatively steady set point for the regulated factor

Controlled variable

some factor that can vary but is held within a narrow range by a control system

Sensor

the component of a control system that monitors the magnitude of the controlled variable

Set point

the desired level at which homeostatic control mechanisms maintain a controlled variable

Integrator

a region that determines efferent output based on processing of afferent input; also called a control center

Effector

the component of a control system that accomplishes the output command by the integrator

Positive feedback

a regulatory mechanism in which the input and the output in a control system continue to enhance each other so that the controlled variable is progressively moved further away from the steady state