1.5 Body Structures and Organ Systems

Anatomy

The study of body structure.

Physiology

The study of the function of the body.

Homeostasis

Achieved when the body’s systems and processes maintain stability.

Cell

The smallest living unit in the body.

Tissue

Groups of similar cells that work together to perform a specific function.

Organ system

A group of organs that work together to perform complicated tasks.

Epithelial tissue

Covers the body and most organs; protects against invading pathogens and toxins.

Nervous tissue

Located in the brain, spinal cord, and peripheral nerves; sends impulses to nerves, muscles, and glands.

Muscle tissue

Contracts and relaxes; includes skeletal, smooth, and cardiac muscle.

Connective tissue

Supports, protects, and gives structure to organs and tissues.

Chromosome

Contain genetic information; humans have 46 chromosomes arranged in 23 pairs.

Gene

A portion of DNA that determines a specific body trait.

Albinism

A genetic disorder characterized by little or no pigmentation in skin, eyes, or hair.

Cystic fibrosis

A life-threatening genetic disease mainly affecting the lungs and pancreas.

Down syndrome

A genetic disorder caused by three copies of chromosome 21, resulting in intellectual disabilities.

Hemophilia

A blood disorder caused by a lack of clotting factor.

Anatomical position

Body is standing upright, facing forward, arms at the sides, and palms facing forward.

Superior

Positioned above another part of the body.

Inferior

Positioned below another part of the body.

Proximal

Closer to the point of attachment.

Distal

Further from the point of attachment.

Sagittal plane

Divides the body into right and left sides.

Transverse plane

Divides the body into upper and lower portions.

Cranial cavity

Contains the brain.

Thoracic cavity

Contains the lungs and heart.

Abdominal cavity

Contains organs such as the liver and intestines.

Pelvic cavity

Contains the bladder.

RUQ (Right Upper Quadrant)

Pain may indicate issues with the gallbladder.

RLQ (Right Lower Quadrant)

Pain may indicate appendicitis.

LUQ (Left Upper Quadrant)

Pain may indicate issues with the spleen.

LLQ (Left Lower Quadrant)

Pain may indicate constipation.