Human Body Orientation – Core Review

Anatomy and Physiology

Anatomy studies body structures by taking either a systemic view (cardiovascular, nervous, skeletal, etc.) or a regional view (head, abdomen, limb). Physiology examines how those structures work, aiming to predict responses to stimuli and explain how internal conditions are kept within narrow limits.

Structural Organization

The body can be examined from the chemical level, through cells, tissues, organs, organ systems, and finally the whole organism.

Overview of Organ Systems

Integumentary encloses and senses; skeletal supports and enables motion; muscular moves and generates heat; nervous detects stimuli and coordinates responses; endocrine secretes hormones; cardiovascular transports and equalises temperature; lymphatic returns fluid and defends; respiratory exchanges gases; digestive processes food; urinary regulates water and removes waste; reproductive produces gametes and hormones and, in females, nurtures offspring.

Life-supporting Functions

Internally, breathing, circulation, digestion, thermoregulation, immunity, homeostatic balance, and cellular metabolism keep us alive. Behaviourally, feeding, hydration, sleep, shelter-seeking, danger avoidance, and reproduction ensure survival. Developmentally, growth, hormonal control, and neural coordination guide maturation and repair.

Homeostasis

Homeostasis is the dynamic stability of internal conditions. It relies on a receptor that detects change, a control centre that sets the desired point, and an effector that corrects deviation. Negative feedback reverses change (e.g. thermal or glucose regulation). Positive feedback amplifies change when necessary (e.g. uterine contractions in labour).

Anatomical Terminology

Precise vocabulary avoids confusion about position, direction, region, or structure. The standard anatomical position is upright, feet forward, arms at sides, palms outward.

Body Planes

Sagittal divides left–right, frontal (coronal) divides front–back, transverse divides upper–lower, and oblique cuts at an angle.

Directional Terms

Anterior/ventral vs posterior/dorsal; superior vs inferior; medial vs lateral; proximal vs distal (within a limb); superficial vs deep; ipsilateral vs contralateral; cephalic (toward the head) vs caudal (toward the tail).

Body Cavities

Dorsal cavity houses brain (cranial) and spinal cord (vertebral). Ventral cavity contains thoracic cavity (pleural, mediastinum, pericardial) and abdominopelvic cavity (abdominal and pelvic), which are separated by the diaphragm.

Abdominopelvic Divisions

Four quadrants (right/left upper, right/left lower) and nine regions (right hypochondriac, epigastric, left hypochondriac; right lumbar, umbilical, left lumbar; right iliac, hypogastric, left iliac) help localise organs and pain.

Movement Terminology

Flexion, extension, lateral flexion, abduction, adduction, rotation (medial or lateral), circumduction, pronation, supination, protraction, retraction, inversion, and eversion describe body motions relative to planes and midline.

Key Definitions

Anatomy – study of structure.
Physiology – study of function.
Metabolism – energy use for vital tasks.
Growth – size increase.
Reproduction – production of new cells or organisms.