An Overview of Anatomy Anatomy Physiology The study of the structure of the human body Physiology The study of body function

Many Levels of Structural Organization Chemical level- Atoms combine to form molecules Cellular level- reflect their particular functions in the body Tissue level- Consist of groups of similar cells (epithelial, connective, muscular, and neural) Organ level- two or more tissue types making an organ with complex function Organ system level- group of organs that cooperate to accomplish a common purpose (example: cardiovascular system with heart and blood vessels)

Organ Systems Overview ORGAN SYSTEM – a group of organs which act together to perform a specific, related function Integumentary Skeletal Muscular Nervous Endocrine Cardiovascular Lymphatic Digestive Respiratory Urinary Reproductive

Gross Anatomy – An Introduction Anatomical position – a common visual reference point Person stands erect with feet slightly apart and eyes forward Palms face anteriorly with the thumbs pointed away from the body Directional terminology – refers to the body in anatomical position Standardized terms of directions are paired terms

Axial region – the main axis of the body Appendicular region – the limbs

Anatomic Terminology Position and Directional Terms ANTERIOR or VENTRAL – front or in front of POSTERIOR or DORSAL – back or in back of CRANIAL – refers to the head of the body CAUDAL – means tail end SUPERIOR – upper or above something INFERIOR – lower or below something MEDIAL – toward the middle LATERAL – toward the side of the body PROXIMAL – toward the point of attachment to the body or the trunk of the body DISTAL – away from the point of attachment to the body SUPERFICIAL (EXTERNAL) – near the surface or outside the body DEEP (INTERNAL) – inside the body

Three Major Planes When a section or cut is made through the body wall or an organ, it is made along an imaginary line called a plane.

Body Planes and Sections Coronal (frontal) plane Lies vertically and divides body into anterior and posterior parts Median (midsagittal) plane Specific sagittal plane that lies vertically in the midline

Body Planes and Sections Transverse plane Runs horizontally and divides body into superior and inferior parts Figure 1.5

Oblique Section Through the Trunk

Banana Sectioned into Planes

Cavities of the Body DORSAL CAVITY – contains brain and spinal cord – the brain is in the CRANIAL CAVITY and the spinal cord is in the SPINAL CAVITY. ANTERIOR or VENTRAL CAVITY contains the THORACIC and ABDOMINOPELVIC CAVITIES The thoracic cavity contains the lungs and heart ABDOMINAL CAVITY contains stomach, intestines, liver, gallbladder and pancreas PELVIC CAVITY contains urinary bladder and reproductive organs

The Balance of Body Functions Survival of the individual and of the genes is the body’s most important business Survival depends on the maintenance or restoration of homeostasis (relative constancy of the internal environment); the body uses negative feedback loops and, less often, positive feedback loops to maintain or restore homeostasis

Negative Feedback Loop The response reverses a change in a controlled condition Like thermostat in your house, the hypothalamus senses when the environment gets cold and triggers other physiological responses – shivering, vasoconstriction of peripheral blood vessels. (in warm environments, sweating and vasodilation)

Positive Feedback Loop Response strengthens the change in a controlled condition Example: When a baby is ready to be born the hypothalamus signals the release of oxytocin which triggers uterus contractions, as the uterus contracts the baby begins to move down in the birth canal which signals the release of more oxytocin and so on…until the baby is born

The Balance of Body Functions All organs function to maintain homeostasis Body functions are related to age; peak efficiency is during young adulthood, diminishing efficiency occurs after young adulthood