Dental Sciences & Prev Dentistry- Ch 6/COMPLETED

anatomy

what is anatomy

Anatomy is the scientific study of the shape and structure of the human body

Basic anatomical reference systems

Planes and body directions

Structural units

Body cavities

Body regions

Planes and Body Directions

Anatomical position is the body standing erect with the feet together and the arms hanging at the sides with the palms facing forward

The sagittal plane is a vertical plane dividing the body from top to bottom and into left and right sections (possibly unequal sections)

The midsagittal plane is vertical, dividing the body into equal left and right halves

The horizontal plane and traverse (same thing) divides the body into superior (upper) and inferior (lower) portions

The frontal plane and cornal (same thing)divides the body into anterior (front) and posterior (back) portions

Directional Terms for the Human Body

Superior top of horizontal plane – Above another part, closer to the head

Inferior bottom of horizontal – Below another part, closer to the feet

Proximal – Closer to a point of attachment, or closer to the trunk of the body

Distal – Farther from a point of attachment, or farther from the trunk of the body

Directional Terms for the Human Body

Lateral – The side, or away from the midline

Medial – Toward, or nearer the midline

Dorsal – On the back

Ventral – On the front

Anterior – Toward the front

Posterior – Toward the back

Structural Units

Cells

Tissues

Organs

Body systems

Cells

Cells, the basic units of structure in the human body, react to stimuli, transform nutrients into energy, grow, and reproduce

The term for specialization of cells is differentiation

The human body contains many types of cells, each with a purpose

Stem Cells

Immature, unspecialized cells in the body

• Can be induced to become other types of cells in the body

There are two primary sources of stem cells

• Embryonic stem cells

• Adult stem cells

Embryonic Stem Cells

Come from embryos that develop from eggs that have been fertilized in a test tube and then are used for research purposes

They are not derived from eggs fertilized in a woman’s body

Currently there are no approved treatments or human trials using embryonic stem cells in the United States

Adult Stem Cells

Can be found in tissues of both adults and children

• Stem cells from bone marrow have been used in bone marrow transplant procedures for many years

Adult stem cells are also found in blood, skin, dental pulp, retina, skeletal muscle, and the brain

Cell Membrane

The cell membrane surrounds the cell body and serves two purposes

• Structural: Separates the contents of the cell from the surrounding environment

• Semipermeable: Allows nutrients to pass through and waste products to leave

Cytoplasm

Gelatinous fluid inside the cell

Contains organelles

• Organelles modify, store, and transport proteins and dispose of cellular wastes

Nucleus

The control center of the cell

Directs the metabolic activities of the cell

The nucleus of every cell (except mature red blood cells) contains a complete set of the body’s chromosomes

The chromosomes contain DNA and RNA, two chemicals that carry all genetic information

Tissues

Formed when many millions of cells with the same shape, size, structure, and function join together to perform a specific function for the body

Types of Tissues

Epithelial tissues are external (skin) or internal body surfaces (mouth, intestines, and so on)

Connective tissue includes fat, tendons, and ligaments

Muscle tissue

• Voluntary (e.g., arms, legs)

• Involuntary (e.g., heart, lungs, stomach)

Nerve tissue includes the brain, spinal cord, and nerves

Organs

Organs are formed when several types of tissues become a group

Organs perform a single function

Organs contain each of four tissue types

• Nerve

• Connective

• Muscle

• Epithelial

Body Systems

A body system is composed of a group of organs working together to perform a major function

Example: Digestive system

• Esophagus

• Stomach

• Small and large intestines

Body Cavities

The two main body cavities

• Dorsal: Back of the body

• Divided into the cranial cavity and the spinal cavity

Ventral: Front of the body

• Subdivided into the thoracic cavity and the abdominopelvic cavity

• The thoracic cavity contains the heart, lungs, esophagus, and trachea

• The abdominal cavity houses the stomach, liver, gallbladder, spleen, and most of the intestines

• The pelvic cavity contains portions of the small and large intestines, the rectum, the urinary bladder, and internal reproductive organs

Body Regions

Axial division

• Head

• Neck

• Trunk

Appendicular region

• Arms

• Legs