The Human Body: An Orientation

Flashcards covering the fundamentals of anatomy and physiology, including levels of organization, organ systems, directional terminology, body cavities, and homeostatic mechanisms.

Anatomy

The study of the structure and shape of the body and its parts and their relationships to one another.

Physiology

The study of how the body and its parts work or function.

Gross anatomy

The study of large, easily observable structures, such as the heart or bones, often involving dissection.

Microscopic anatomy

The study of body structures that are too small to be seen with the naked eye, such as cells and tissues.

Chemical level

The simplest level of structural organization where atoms combine to form molecules such as water, sugar, and proteins.

Atoms

Tiny building blocks of matter that combine to form molecules.

Cells

The smallest units of all living things.

Tissues

Groups of similar cells that have a common function.

Organ

A structure composed of two or more tissue types that performs a specific function for the body.

Organ system

A group of organs that work together to accomplish a common purpose.

Organismal level

The highest level of structural organization, representing the sum total of all structural levels working together to keep the individual alive.

Integumentary system

The external covering of the body (skin) that waterproofs the body, cushions deep tissues, and produces vitamin D.

Skeletal system

Consists of bones, cartilages, and joints; it supports the body and provides a framework for movement.

Muscular system

The system whose primary function is to contract or shorten to facilitate movement and maintain posture.

Nervous system

The body’s fast-acting control system, consisting of the brain, spinal cord, nerves, and sensory receptors.

Endocrine system

Controls body activities more slowly than the nervous system by secreting hormones into the blood.

Hormones

Chemical molecules produced by endocrine glands that regulate processes such as growth and reproduction.

Cardiovascular system

Consists of the heart and blood vessels; it uses blood to deliver oxygen and nutrients to cells and remove wastes.

Lymphatic system

Returns fluid leaked from blood to the bloodstream and houses white blood cells involved in immunity.

Respiratory system

Supplies the body with oxygen and removes carbon dioxide via nasal passages, pharynx, larynx, trachea, bronchi, and lungs.

Digestive system

A tube running from mouth to anus that breaks down food and absorbs nutrients and water.

Urinary system

Removes nitrogen-containing wastes from the blood and maintains water, salt, and acid-base balance.

Reproductive system

The system responsible for the production of offspring through the use of sperm and eggs.

Responsiveness (irritability)

The ability to sense changes (stimuli) in the environment and then react to them.

Metabolism

A broad term referring to all chemical reactions that occur within the body and its cells.

Adenosine triphosphate (ATP)

Energy-rich molecules that power cellular activities.

Nutrients

Chemicals taken in through food used for energy and cell building; includes carbohydrates, proteins, fats, minerals, and vitamins.

Normal body temperature

The level at which metabolic reactions continue efficiently, typically $37^{\circ}C$ ($98.6^{\circ}F$).

Atmospheric pressure

The force exerted on the surface of the body by the weight of air, essential for breathing and gas exchange.

Anatomical position

A standard reference position where the body is erect, feet parallel, and arms at the sides with palms facing forward.

Superior (cranial or cephalic)

Toward the head end or upper part of a structure or the body; above.

Inferior (caudal)

Away from the head end or toward the lower part of a structure or the body; below.

Anterior (ventral)

Toward or at the front of the body; in front of.

Posterior (dorsal)

Toward or at the backside of the body; behind.

Medial

Toward or at the midline of the body; on the inner side of.

Lateral

Away from the midline of the body; on the outer side of.

Proximal

Close to the origin of the body part or the point of attachment of a limb to the body trunk.

Distal

Farther from the origin of a body part or the point of attachment of a limb to the body trunk.

Superficial (external)

Toward or at the body surface.

Deep (internal)

Away from the body surface; more internal.

Sagittal section

A cut along the lengthwise (longitudinal) plane of the body, dividing it into right and left parts.

Median (midsagittal) section

A sagittal cut down the median plane resulting in equal right and left parts.

Frontal (coronal) section

A cut along a lengthwise plane that divides the body or organ into anterior and posterior parts.

Transverse (cross) section

A cut along a horizontal plane, dividing the body or organ into superior and inferior parts.

Dorsal body cavity

Contains the cranial cavity (housing the brain) and the spinal cavity (housing the spinal cord).

Ventral body cavity

Contains the thoracic cavity and the abdominopelvic cavity; partitioned by the diaphragm.

Homeostasis

The body’s ability to maintain relatively stable internal conditions even though the outside world is continuously changing.

Receptor

A type of sensor that monitors and responds to stimuli by sending input information to the control center.

Control center

Determines the set point at which a variable is maintained and analyzes incoming information to determine a response.

Effector

Provides the means for the control center's response (output) to the stimulus.

Negative feedback mechanism

A control system where the net effect of the response to the stimulus is to shut off the original stimulus or reduce its intensity.

Positive feedback mechanism

A control system that increases the original disturbance and pushes a variable farther from its original value.

Homeostatic imbalance

A disturbance in homeostasis, which is often a cause of disease and changes associated with aging.