Dental Sciences & Prev Dentistry- Test 6/7/8- COMPLETE

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

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

a 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

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

Lateral-

The side, or away from the midline

Medial-

Toward, or nearer the midline

Dorsal-

On the back

Ventral-

On the front

Anterior-

Toward or at the front

Posterior – Toward the back

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

Physiology is

the study of how living things function

Body Systems

The human body has 10 systems

• Skeletal, Muscular, Cardiovascular, Nervous, Respiratory, Digestive, Endocrine, Urinary, Integumentary, Reproductive

Each system has specific organs within it

Each body system performs specific functions

In a healthy human being, all 10 systems are functioning

Skeletal System

There are 206 bones in the human body

For descriptive purposes, the skeleton is divided into the axial and appendicular skeletal systems

Axial Skeleton

Consists of the skull, spinal column, ribs, and sternum

Its function is to protect the major organs of the nervous, respiratory, and circulatory systems

The bones of the skull are of primary importance to the dental assistant

Appendicular Skeleton

Consists of the upper extremities and shoulder girdle plus the lower extremities and pelvic girdle

It protects the organs of digestion and reproduction

Bone

Bone is the hard connective tissue that makes up most of the human skeleton

It consists of an organic component (the cells and matrix) and an inorganic (mineral) component

• The minerals, mainly calcium and phosphate, give rigidity to bone

• These minerals stored in bone also act as a mineral reservoir to maintain essential blood mineral concentrations in times of inadequate supply in the body

The Periosteum

A specialized connective tissue covering all bones of the body

It is responsible for the life of the bone and is capable of repair

• The outer layer is a network of dense connective tissue containing blood vessels

• The inner layer is loose connective tissue containing osteoblasts

Kinds of Bone

Compact bone

• Hard, dense, and very strong

• It forms the outer layer of bone, where it is needed for strength

Cancellous bone

• Lighter in weight, but not as strong as compact bone

• It is found in the interior of bones

Trabeculae

Bony spicules in cancellous bone that form a mesh of intercommunicating spaces filled with bone marrow

Appear as a weblike structure on radiographs

Bone Marrow

Inside the spaces of cancellous bone are two types of bone marrow

• Red marrow

       * Filled with blood vessels

       * Makes red and white blood cells and platelets

• Yellow marrow

      * Contains mainly fat cells

      * Found primarily in the shafts of long bones

Cartilage

It is tough, yet more elastic than bone

It is found where bones join together

Nonvascular connective tissue

In addition to the ends of bone, cartilage gives form to the nose and ears

Joints

Areas where two bones come together

Three basic types of joints

• Fibrous: Do not move; for example, the sutures of the skull

• Cartilaginous: Made of connective tissue and cartilage; for example, the joints between the bones of the vertebrae

• Synovial: Movable joints, account for most of the joints in the body

Disorders of the skeletal system

Arthritis: Inflammation of a joint, it affects bones and joints that can cause pain, inflammation, and mobility issues.

Fracture: A break in a bone or cartilage caused by stress on the bone, often caused by trauma, resulting in pain, swelling, and sometimes deformity.

Gout: inflammation of a joint, caused by accumulation of uric acid crystals. usually affects the big toe. it becomes red, swollen, warm, shiny, and hypersensitive to touch.

Osteomyelitis: infection of the bone caused by bacteria, fungi, or contaminated material such as an artificial joint. can caused sudden onset fever, limited movement, severe pain in the affected area.

Osteoporosis: age related disease where the bone demineralized, resulting in loss of bone density which increases the chances of fractures. Causes frequent fractures especially to the vertebrae, wrist, or hip. causes back pain and can decrease height.

Sprain: injury to a joint caused by stretching it beyond its limit. causes pain, swelling, bruising, abnormal movement, and joint weakness

Muscular System

Gives us the ability to stand, walk, run, jump, move our eyes, smile, and frown

It is composed of more than 600 individual muscles

For muscles to make the body move, they must work together

Each muscle consists of muscle tissue, connective tissue, nerve tissue, and vascular (blood) tissue

Types of Muscles

Striated muscle

• So named because dark and light bands in the muscle fibers yield a striped, or striated, appearance

• Known as skeletal or voluntary muscle

• Attached to the bones of the skeleton; makes bodily motion possible

Smooth muscle

• Moves the internal organs, such as the digestive tract, blood vessels, and secretion ducts leading from glands

Cardiac muscle

• Also known as myocardium, is the specialized, involuntary muscle tissue that forms the heart wall. It is responsible for the heart's rhythmic contractions that pump blood throughout the body.

Smooth Muscle

Involuntary muscle is under the control of the autonomic nervous system and is not controlled voluntarily

Visceral muscle is so named because it is found in the visceral (internal) organs, except the heart

It is also found in hollow structures such as the digestive and urinary tracts

Cardiac Muscle

Striated in appearance but resembles smooth muscle in action

Cardiac muscle forms most of the walls of the heart, and contraction of this muscle results in the heartbeat

It combines the power of striated voluntary muscles with the steady reliability of smooth, involuntary ones

Muscle Function

Contraction is the tightening of a muscle, during which it becomes shorter and thicker

Relaxation occurs when a muscle returns to its original form or shape

• The muscles of the body are arranged in opposing pairs so that when one contracts, the other relaxes

• It is these contrasting actions that make motion possible

Muscle origin

• The place where the muscle begins (originates)

• This is the more fixed attachment, the end of the muscle that is closer to the midline of the body, or both

Muscle insertion

• The place where the muscle ends (inserts)

• It is the more movable end, the portion of the muscle that is farther from the midline of the body, or both

Disorders of the Muscular system

Contusions: soft tissue trauma. causes swelling, tenderness, and localized hemorrhaging and bruising can restrict range of motion without producing loss of joint stability.

Strain: injury to a muscle that has been stretched beyond its limits. Small blood vessels around the area rupture which causes swelling in the area. the area becomes tender and painful muscles spasms my occur.

Progressive Muscular Dystrophy: includes nine types, all with unknown causes. progressive muscle atrophy with organ involvement and weakness.

Sprain: injury to a joint that has been stretched beyond its normal range which results in a tear. depending on the severity of the damage it may include pain in the affected area, swelling, bruising, abnormal motion, and joint weakness.

Cardiovascular System

Consists of the following:

• Circulatory system

• Heart

• Lymphatic system

These systems provide life-sustaining capabilities for the survival of body cells and tissues

Circulatory System

The two primary functions of the circulatory system are:

• Transporting oxygen and nutrients to the cells and transporting carbon dioxide and waste products from the cells, as well as transporting hormones and antibodies throughout the body

• Regulating body temperature and chemical stability

Heart

Each day the heart pumps 4000 gallons of blood at a speed of 40 mph through 70,000 miles of vessels

The heart is a hollow muscle with four chambers

Heart size varies from individual to individual but is generally the same as a closed fist

The Pericardium

The heart is enclosed in a double-walled membranous sac known as the pericardium

Pericardial fluid between the layers prevents friction when the heart beats

Heart Chambers

The heart functions as a double pump

• The right side pumps blood to the lungs

• The left side sends blood to the rest of the body

The coronary vessels supply blood to the heart muscle

Each side is subdivided into an upper and a lower chamber

Heart Valves

One-way valves prevent the backflow of blood and separate the chambers of the heart by opening and closing with each heartbeat

• The tricuspid valve is found between the right atrium and the right ventricle

• The mitral valve has two cusps and lies between the left atrium and the left ventricle

Two semilunar valves have three crescent-shaped flaps

• Pulmonary semilunar valve allows blood to flow from the right ventricle into the pulmonary artery

• Aortic semilunar valve allows blood flow from the left ventricle into the aorta

Blood Vessels

Arteries are large blood vessels that carry blood away from the heart to all regions of the body

Capillaries are a system of microscopic vessels that connect the arterial and venous systems

Veins form a low-pressure collecting system to return the waste-filled blood to the heart

Blood and Blood Cells

Plasma is a straw-colored fluid that transports nutrients, hormones, and waste products

Plasma is 91% water

Red blood cells contain the blood protein hemoglobin, which plays an essential role in oxygen transport

White blood cells, also known as leukocytes, have the primary function of fighting disease in the body

Disorders of the cardiovascular system

Cardiomyopathy: Heart muscle disease; cause is unknown; usually leads to heart failure. Fatigue, weakness, heart failure, chest pain, and shortness of breath.

Coronary Artery Disease: Caused by a buildup of cholesterol plaques in coronary arteries, which reduce blood flow to the heart. Chest pain, shortness of breath; pain may radiate to neck, jaw, arm, or back; ashen or gray color and anxiety are also common.

Endocarditis: Inflammation of the endocardial layer of the heart; can be caused by bacteria, virus, tuberculosis, or cancer. High fever, heart murmur, blood clots, joint pain, fatigue, shortness of breath, and chest pain.

Heart Failure: The heart can no longer pump an adequate supply of blood; can be caused by disease, congenital problems, hypertension, lung disease, or valve problems. Breathlessness, weakness, fatigue, dizziness, confusion, hypotension, or death.

Pericarditis: Inflammation of the pericardial layer of the heart; can be caused by bacteria, virus, tuberculosis, or cancer. High fever, heart murmur, blood clots, enlarged spleen, fatigue, joint pain, weight loss, or shortness of breath.

Lymphatic System

The structures of the lymphatic system are:

• Lymph vessels

• Lymph nodes

• Lymph fluid

• Lymphoid organs

Drainage vessels absorb excess protein from tissues and return it to the bloodstream

Lymphoid organs contribute to the immune system to assist with destruction of harmful microorganisms

Lymph Vessels

Lymph capillaries are thin-walled tubes that carry lymph from the tissue spaces to the larger lymphatic vessels

• Similar to veins, lymphatic vessels have valves that prevent the backflow of fluid

• Lymph fluid always flows toward the thoracic cavity, where it empties into veins in the upper thoracic region

Specialized lymph vessels, called lacteals, are located in the small intestine

• Lacteals aid in the absorption of fats from the small intestine into the bloodstream

Lymph Nodes

Small, round or oval structures that are located in the lymph vessels

They fight disease by producing antibodies; this is part of the immune reaction

Major lymph node sites of the body include:

• Cervical (in the neck)

• Axillary (under the arms)

• Inguinal (in the lower abdomen)

Lymphoid Organs

Tonsils, Spleen

Disorders of the lymph system

Lymphangitis: Inflammation of peripheral lymphatic vessels, usually caused by infection. Red streaks that extend up the arm or leg, with enlarged, tender lymph nodes.

Lymphadenopathy: Swelling or enlargement of one or more lymph nodes; can result from infection, inflammation, or neoplasm. Painful swelling of lymph nodes.

Lymphedema: Swelling of soft tissues caused by increased lymph. Painful swelling of limbs.

Neurons

The basic function of neurons is to direct communication or nerve impulses

Neurons have the properties of excitability, the ability to respond to a stimulus, and conductivity, which refers to transmission of an impulse

Three types of neurons

• Sensory neurons-emerge from the skin or sense organs and carry Impulses toward the brain and spinal cord.

• Motor neurons- carry impulses away from the brain and spinal cord and towards the muscles and glands.

• Associative neurons- carry impulses from one neuron to another.

Central Nervous System

Brain

• The brain is the primary center for the regulation and coordination of the body’s activities, and each part of the brain controls different aspects of body function

Spinal cord

• The spinal cord carries all of the nerves that affect the limbs and lower part of the body and is the pathway for impulses going to and from the brain

Peripheral Nervous System

The autonomic nervous system controls unconscious activities such as breathing, heart rate, body temperature, blood pressure, and pupil size

The somatic nervous system controls conscious activites

Disorders of the nervous system

Bell's Palsy: Paralysis of the facial (seventh cranial) nerve that causes distortion on the affected side of the face. The person may not be able to open an eye or close the mouth. The condition may be unilateral or bilateral.

Multiple Sclerosis: A chronic autoimmune disease affecting the central nervous system, characterized by the destruction of myelin sheaths surrounding nerve fibers, leading to communication problems between the brain and the rest of the body.

Respiratory System

Delivers oxygen to the millions of cells in the body and transports the waste product carbon dioxide out of the body

The respiratory system consists of the:

• Nose

• Paranasal sinuses

• Pharynx

• Epiglottis

• Larynx

• Trachea

• Alveoli

• Lungs

Nose

Air enters the body through the nostrils of the nose and passes through the nasal cavity

• The nose is divided by a wall of cartilage called the nasal septum

The nose and the respiratory system are lined with mucous membrane, a specialized form of epithelial tissue

Incoming air is filtered by the cilia, which are thin hairs that are attached to the mucous membrane just inside the nostrils

Pharynx

After passing through the nasal cavity, air reaches the pharynx, which is commonly known as the throat

Three divisions of the pharynx

• The nasopharynx is located behind the nose and above the soft palate

• The oropharynx extends from the soft palate above to the level of the epiglottis below

• The laryngopharynx extends from the level of the epiglottis above to the larynx below

Epiglottis

The oropharynx and the laryngopharynx serve as a common passageway for food from the mouth and air from the nose

During swallowing, the epiglottis acts as a lid and covers the larynx so that food does not enter the lungs

Larynx

Also known as the voice box, it contains the vocal bands, which make speech possible

The larynx is protected and is held open by a series of cartilaginous structures

The largest cartilage forms the prominent projection in front of the neck, called the “Adam’s apple”

Trachea

Air passes from the larynx to the trachea

The trachea extends from the neck into the chest, directly in front of the esophagus

It is protected and held open by a series of C-shaped cartilaginous rings

Lungs

The trachea divides into two branches called bronchi

• Each bronchus leads to a lung, where it divides and subdivides into increasingly smaller branches; bronchioles are the smallest of these branches

Alveoli are tiny grapelike clusters found at the end of each bronchiole

• Exchange of gases between the lungs and the blood takes place in the alveoli

Digestive System

The role of the digestive system is to provide the body with the nutrients, water, and electrolytes necessary for life

The digestive system functions under involuntary control

Digestive Process:

Ingestion: Occurs when food is taken into the mouth

Digestion: Begins in the mouth as food is masticated with saliva and then swallowed

Movement: Chewed food is subjected to peristalsis, the rhythmic wavelike contractions that move the food through the digestive tract

Absorption: Nutritional elements in the gastrointestinal tract pass through the lining of the gastrointestinal tract and into the bloodstream

Elimination: In the large intestine, solid by-products of digestion are eliminated from the body in feces

Structures of the Digestive System

The major structures of the digestive system are the:

Mouth

Pharynx

Esophagus

Stomach

Small intestine

Large intestine

Liver, gallbladder, and pancreas

Endocrine System

The endocrine system consists of ductless glands and tissues that help regulate the body’s activities

The glands secrete hormones directly into the blood

These hormones affect metabolism, growth, and development

The hormones are secreted directly into the bloodstream, not through a duct

Endocrine Glands

Thyroid gland

Parathyroid gland

Ovaries

Testes

Pituitary gland

Pancreas

Adrenal medulla

Urinary System

The urinary system is also known as the excretory system

Its principal function is to maintain fluid volume and composition of the body fluids

Waste products leave the body in the form of urine, and the needed substances are returned to the blood

Organs of the Urinary System

The kidneys are the site of formation of urine, which carries waste materials away from the blood

The ureters transport the urine from the kidney

The bladder stores urine until it can be eliminated

The urethra is the conduit through which the bladder is emptied during the process of urination

Integumentary System

The skin is the body’s first line of defense against disease

Functions of the skin system include:

• Helps regulate body temperature

• Provides a barrier that prevents bacteria from entering the body

• Excretes liquids and salts

• Provides sensitivity to touch

• Uses ultraviolet rays from the sun to convert chemicals into vitamin D necessary for absorption of calcium

Skin Structures

The skin is composed of different layers, including the following:

Epidermis

• The outer layer of the skin; has no blood supply of its own

Dermis

• Contains many free nerve endings and receptors, which allow for detection of touch, temperature, and pain

Subcutaneous fat

• A layer of loose connective tissue that anchors the skin to underlying organs; insulates the body against heat loss and cushions underlying organs

Skin Appendages

Hair

• Enclosed in a follicle and consists of a root and a shaft

Nails

• Contains a root and a body

Glands

• Sebaceous glands

• Sudoriferous glands

• Apocrine sweat glands

Female Reproductive System

External

• Mons pubis

• Labia majora and minora

• Vulva

• Clitoris

Internal

• Ovaries

• Fallopian tubes

• Uterus

• Vagina

Male Reproductive System

Produces and transports sperm

In the male, several organs serve as parts of both the urinary tract and reproductive system

This system consists of the:

• Excretory ducts

• Testes

• Prostate

• Seminal vesicles

Interaction Among the Ten Body Systems

Body systems do not operate independently

Exert important effects on each other

Something happening to one system tends to affect other systems

Embryology is

the study of prenatal development in the stages before birth

Histology is

the study of the structure and function of the tissues on a microscopic level

Oral Embryology

Pregnancy begins with conception, also known as fertilization

• Occurs when sperm penetrates and fertilizes ovum

Birth occurs, on average, 38 weeks after conception, or 40 weeks after the beginning of the last menstrual period (LMP)

• For general descriptive purposes, this is divided into three trimesters of 3 months each

In embryology, developmental age is based on the date of conception, which is assumed to have occurred 2 weeks after the LMP

Prenatal Development

The preimplantation period is the first week

The embryonic period extends from the beginning of the second week to the end of the eighth week; at this time the developing life is known as an embryo

The embryonic period is the most critical time in development

The fetal phase begins with the ninth week and lasts until birth

Embryonic Development of the Face and Oral Cavity

The face and its related tissues begin to form during the fourth week of prenatal development within the embryonic period

During this time, the rapidly growing brain of the embryo bulges over the oropharyngeal membrane, beating heart, and stomodeum

Primary Embryonic Layers

During the third week of development, the cells of the embryo form the three primary embryonic layers

• Ectoderm

• Mesoderm

• Endoderm

Early Development of the Mouth

Fourth week

• The stomodeum, or primitive mouth, and primitive pharynx merge, and the stomodeum develops into part of the mouth

Fifth week

• The embryo is approximately 5 mm long

• The heart is prominent and bulging

Branchial Arches

By the end of the fourth week, six pairs of branchial arches have formed

The first branchial arch forms the lower lip, the muscles of mastication, and the anterior portion of the alveolar process of the mandible

The second branchial arch forms the styloid process, stapes of the ear, stylohyoid ligament, part of the hyoid bone, and more

Other branchial arches form the body of the hyoid, the posterior tongue, and structures of the lower throat

Development of the Hard and Soft Palates

The formation of the palate in the embryo, and later in the fetus, takes several weeks

The palate is formed from two separate embryonic structures

• Primary palate

• Secondary palate

Any disruption in the process may result in a cleft lip or cleft palate

Prenatal Facial Development

The development of the human face occurs chiefly between the fifth and eighth weeks

• At 1 month, the forehead is the dominant feature

• At 4 months, the face looks human, the hard and soft palates are beginning to form, and the primary dentition has begun

• During the last trimester, fat is laid down in the cheeks in what is known as “sucking pads”

            *These give a healthy full-term fetus the characteristic round facial contours

Prenatal Tooth Development

The earliest signs of tooth development are found in the anterior mandibular region when the embryo is 5 to 6 weeks old

• By the 17th week, development of the permanent teeth has begun

• At birth, there are normally 44 teeth in various stages of development

• Enamel formation is well under way on all primary dentition and the beginnings of the permanent first molars

Developmental Disturbances

Disturbances at any stage of dental development may cause a wide variety of anomalies

These can be caused by:

Genetic factors

• In prenatal tooth development, the genetic factor that is most often a concern is tooth and jaw size

Environmental factors

• Adverse environmental influences called teratogens include infections, drugs, and exposure to radiation

Known Teratogens Involved in Congenital Malformations

• Drugs: ethanol, tetracycline, phenytoin (Dilantin), lithium, methotrexate, aminopterin, diethylstilbestrol, warfarin, thalidomide, isotretinoin (retinoic acid), androgens, progesterone

• Chemicals: methylmercury, polychlorinated biphenyls

• Infection: rubella, herpes simplex, human immunodeficiency virus (HIV), syphilis

• Radiation: high levels of ionizing type

Diagnostic levels of radiation should be avoided but have not been directly linked to congenital malformations.