Human Anatomy & Physiology: Body Regions, Planes, and Homeostasis

Anatomy

the study of the structure and relationship of these structures of the human body

Physiology

the study of the functions of these structures

The Anatomic Position

standing upright, upper limbs by the sides, the face and the palms of the hands directed forward, lower limbs close together with the feet parallel

Prone

body is lying face DOWN

Supine

body lying face UP

Median Sagittal Plane

a vertical plane passing through the center of the body that divides the body into equal right and left halves

Frontal Plane

a vertical plane passing through the body from side to side that divides the body into anterior (front) and posterior (back) portions

Transverse Plane

horizontal line that divides the body into superior (upper) and inferior (lower) portions

Paramedian Plane

a vertical plane that does pass through the center of the body and divides the body into unequal right and left halves

Oblique Plane

passes through the body or an organ at an oblique angle

Body Regions

Principal regions include Head, Neck, Trunk, Upper limbs, Lower Limbs

Head

consists of skull and face; skull encloses the brain and face includes eyes, nose, mouth, forehead, cheeks and chin

Neck

supports head and connects it to the trunk

Trunk

consists of the chest, abdomen and pelvis

Upper Limb

attached to the trunk; consists of the shoulder, armpit, arm, forearm, wrist and hand

Lower Limb

attached to the trunk; consists of the buttock, thigh, leg, ankle and foot

Groin

an area in the front surface marked by a crease

Body Cavities

spaces within the body that help protect, separate and support internal organs

Cranial Cavity

formed by the bones of the skull; contains the brain

Vertebral Canal

formed by the vertebral column; contains the spinal cord and the beginnings of the spinal nerves

Thoracic Cavity

aka Chest Cavity; formed by the ribs, muscles of the chest, the sternum, the thoracic portion of the vertebral column

Pericardial Cavity

A fluid filled space that surrounds the heart

Pleural Cavity

fluid filled space that surrounds each lung

Mediastinum

the central part of the thoracic cavity; it is between the lungs, extending from the sternum to the vertebral column and from the first rib to the diaphragm.

Abdominopelvic Cavity

Extends from the diaphragm to the groin, encircled by the abdominal muscular wall and the bones and muscles of the pelvis.

Abdominal Cavity

Superior portion that contains the stomach, spleen, liver, gallbladder, small and large intestines.

Pelvic Cavity

Inferior portion that contains the urinary bladder, portions of the large intestine and internal organs of the reproductive system.

Chemical Level

Atoms are the smallest units of matter, and molecules are two atoms joined together.

Cellular Level

Cells are the basic structural and functional units of an organism, and the smallest living units of the body.

Tissue Level

Tissues are groups of cells that work together to perform a particular function, consisting of 4 types: epithelial tissue, connective tissue, muscular tissue, and nervous tissue.

Organ Level

Different types of tissues joined together to perform a particular function.

System Level

Related organs joined together.

Organismal Level

Any living individual with all of the parts of the human body functioning together.

Metabolism

Sum of all chemical processes, divided into catabolism (breaking down of complex chemicals into simpler components) and anabolism (building up of complex substances from smaller and simpler components).

Responsiveness

The body's ability to detect and respond to changes.

Movement

Motion of the whole body, individual organs, single cells and even tiny structures inside cells.

Growth

Increase in body size that results from an increase in the size of existing cells, number of cells or both.

Differentiation

The development of a cell from an unspecialized to a specialized state.

Reproduction

Formation of new cells for tissue growth, repair or replacement, and the production of a new individual.

Homeostasis

Condition of equilibrium (balance) in the body's internal environment, a dynamic condition where there is a constant interaction of the body's regulatory processes.

Body Fluids

An important aspect of homeostasis, dilute watery solution containing dissolved chemicals, found inside (intracellular) and outside (extracellular) of cells.

Interstitial Fluids

Regulated closely for proper functioning of body cells, called the body's internal environment, can deliver nutrient-rich products and remove cellular waste.

Control of Homeostasis

Nervous System sends electrical signals (nerve impulses or action potentials) to organs that can counteract changes from the balanced state, and Endocrine system employs glands which secrete messenger molecules (Hormones) into the bloodstream.

Feedback Loop

Cycle of events which keeps the body's condition in homeostasis, consisting of three basic components: receptor, control center, and effector.

Positive Feedback

Strengthens or reinforces a change in one of the body's controlled conditions.

Negative Feedback System

Reverses a change in a controlled condition, activity is influenced by effectors which send stimulus towards the control center which negates initial response.

Example of Negative Feedback

Blood pressure control.

Example of Positive Feedback

Child Birth.