Chapter 1: The Human Body: An Orientation

Anatomy

Study of the structure of living organisms.

Atom

Smallest particle of an elemental substance that exhibits the properties of that element: composed of protons, neutrons, and electrons.

Contractility

Ability to shorten forcibly when stimulated

Control center

The organ/area of the body that contains the information about the range at which a variable is to be maintained.

Cytology

The study of cells.

Histology

The study of tissues.

Effector

Muscle (skeletal, smooth, cardiac) or gland capable of being activated by nerve impulses.

Gross anatomy

The study of large body structures visible to the naked eye, such as the heart, lungs, and kidneys.

Homeostatic imbalance

A disease that causes a disturbance in homeostasis.

Molecule

Particle consisting of two or more atoms joined together by chemical bonds.

Metabolism

Sum total of the chemical reactions occurring in the body's cells.

Negative feedback mechanism

The most common homeostatic control mechanism whose net effect is that the output of the system shuts off the original stimulus or reduces its intensity.

Microscopic anatomy

Deals with structures too small to be seen by naked eye.

Multicellular

An organism consisting of more than one cell.

Organ

A part o the body formed of two or more tissues and adapted to carry out a specific function.

Organism

The living organism, which represents the sum total of all its organ systems working together to maintain life.

Organelle

A small cellular structure that performs a specific metabolic function for the cell as a whole.

Organ system

A group of organs that work together to perform a vital body function.

Physiology

Study of the function of living organisms.

Positive Feedback Mechanism

Feedback that tends to cause the level of a variable to change in the same direction as an initial change.

Receptor

Some type of sensor that monitors the environment and responds to changes.

Tissue

A group of similar cells and their intercellular substance specialized to perform a specific function.

Variable

The factor or event being regulated by the human body, such as temperature or blood glucose level.

Stimulus

A change in a variable that causes a deviation away from the acceptable set point of the variable.

Homeostasis

A state of body equilibrium or stable internal environment of the body.