Human Anatomy & Physiology I - Orientation & Homeostasis

Vocabulary flashcards focusing on anatomical terminology, directional terms, body planes, life processes, homeostatic components, negative and positive feedback systems, and clinical connections.

Anatomical Position

A standard body orientation where the body is erect, feet are slightly apart, palms face forward with thumbs pointing away from the body, and the head faces forward.

Superior (cranial)

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.

Ventral (anterior)

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

Dorsal (posterior)

Toward or at the back 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

Closer 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 Plane

A anatomical plane that divides the body vertically into right and left parts.

Midsagittal (Median) Plane

A sagittal plane that lies directly on the midline of the body.

Parasagittal Plane

A sagittal plane that is offset from the midline of the body.

Frontal (Coronal) Plane

A plane that divides the body into anterior (front) and posterior (back) parts.

Transverse (Horizontal) Plane

A plane that divides the body into superior (upper) and inferior (lower) parts.

Oblique Plane

A plane that passes through the body at an angle between the transverse and sagittal or frontal planes.

Essential Life Processes

The six vital functions required for survival: organization, metabolism, growth & development, responsiveness, regulation/movement, and reproduction.

Homeostasis

The ability to maintain a relatively stable internal environment in a dynamic state of equilibrium despite constant external changes.

Normal Value Ranges in Homeostasis

Key health baselines including body temperature ($98.6^\text{o}\text{F}$), blood glucose ($80\text{--}110\text{ mg/dL}$), blood pressure ($90\text{--}120/60\text{--}80\text{ mm Hg}$), and blood pH ($7.1$).

Receptor (Sensor)

A homeostatic control component consisting of sensory nerves that monitors the environment and detects changes (stimuli) to send information along the afferent pathway to the control center.

Control Center

A homeostatic component in the nervous or endocrine system that determines the set point for a variable, evaluates incoming information, and determines the appropriate course of action.

Effector

A body structure that receives output commands from the control center along the efferent pathway to provide the means for response to a stimulus.

Negative Feedback System

A homeostatic control mechanism where the output reduces or reverses the original stimulus, bringing the variable back toward its normal baseline setting and turning off once restored.

Antidiuretic Hormone (ADH) Control Mechanism

A negative feedback example where decreased blood volume prompts ADH release, causing the kidneys to reabsorb water and raise blood volume, which shuts off further ADH release.

Positive Feedback System

A control mechanism where the response enhances or exaggerates the original stimulus in the same direction until a critical point is reached to allow the system to reset.

Oxytocin Response in Childbirth

A positive feedback process where oxytocin release causes uterine contractions, which further stimulates additional oxytocin release to increase contraction strength and frequency until birth occurs.

Blood Clotting Mechanism

A positive feedback process initiated by a break in a blood vessel wall, causing platelets to adhere and release chemicals that continuously recruit more platelets until a clot seals the break.

Pyrogens

Chemicals released by immune cells during an infection that cause the hypothalamus to raise its temperature set point, triggering shivering and vasoconstriction until a fever is induced.