Basic Histology Flashcards
What is histology?
Science of microscopic structures and cell function
Helps us to understand renewal, repair, aging and pathology that affects human cells tissues organs and systems
What is the cell/plasma membrane made of and what does it enable?
Composed of a phospholipid bilayer and proteins
What is cytoplasm?
 semi fluid medium, contains organelles
What is the nucleus?
Command Center, produces DNA and RNA and contains genetic code (chromatin/chromosomes)
What are mitochondria?
Powerhouse of the cell, produce adenosine triphosphate (ATP)
What are ribosomes?
Produce proteins, protein type depends on location
What is the smooth endoplasmic reticulum?
Synthesize lipids, phospholipids and steroids
What is the rough endoplasmic reticulum?
Ribosomes on the surface, transports proteins via vesicles
What is the Golgi complex?
Modifies proteins from the endoplasmic reticulum for exocytosis and produces lysosomes
Mucus secretory products for salivary gland‘s
What are centrosomes
Contain centrioles, which form mitotic spindle’s during cell division
What is the cytoskeleton? What is it composed of
Supports and Compartmentalizes
Microfilaments maintain shape and intracellular material transport
Microtubules assist in forming cilia/flagella, centrioles and mitotic spindle‘s
*What are intermediate filaments?
Structural proteins of hair and skin. Masticatory mucosa
Tonofilaments- intracellular junctions
Keratins- (papilla) attached gingiva, dorsum of tongue
What are vacuoles
 small, fluid filled cavities in the cell
What is the function of lysosomes
Phagocytosis of intracellular and extracellular waste. Digestible waist is recycled indigestible waste forms a residual body
What do chromosomes form from?
 chromatin
What are the five phases of mitosis?
Interphase Prophase Metaphase Anaphase Telophase
 what happens during interphase
Cell growth, metabolism, organelle replacement, substance production
Chromatin & centrosome
 what happens during prophase
Chromosomes form and centrioles polarize and form spindles, cell membrane disintegrates
What happens during metaphase
Spindle spread, chromosomes align and center
Centromeres
What happens during anaphase
Centromere‘s split chromosomes forming 2 chromatids and they polarize via mitotic spindle‘s
What happens during telophase
Division forms two daughter cells and the membrane reappears
What is extra cellular material?
Intercellular substance and tissue fluid
What is intercellular substance
Product of living cells
Is among cells of tissues and holds them together
Is a medium for passage of nutrients and waste from cell to capillaries and vice versa
What is amorphous/ground substance?
Found in intercellular substance
Mucopolysaccharide/glycosaminoglycan= hyaluronic acid
Barrier to foreign material and medium for exchange of gases and metabolic substances
Fibrous/formed elements
Found in Intercellular substance
Connective tissue protein fibers
Collagen
Elastin
Reticular
Oxylantan
Where is oxylantan found?
In the PDL space
What is tissue fluid and what does it do?
Derived from blood plasma and contains plasma proteins
Diffuses through capillaries and drains back via lymphatics
Dissolves, mixes and transports substances; enables chemical reactions
What are the four classifications of tissue?
Epithelium
Connective
Muscle
Nerve
What are the two types of epithelium?
 simple and stratified
What are the different types of simple epithelium?
Squamous, cuboidal, columnar, pseudostratified
What are the different types of stratified epithelium
Squamous (keratinized, non-keratinized), cuboidal, columnar, transitional
Glandular tissue (specialized)
What are the different types of connective tissue?
Connective tissue proper- specialized (adipose, fibrous, elastic, reticular)- solid soft
Cartilage- Solid firm
Bone- solid rigid
Blood, lymph- fluid
Types of muscle tissue
Involuntary: smooth, cardiac
Voluntary: skeletal
What are the different types of nerve tissue
Afferent: sensory
Efferent: motor
What do all tissues have but also differ in?
All tissues have cells, intracellular substance and tissue fluid.
Differ in form and the number of cells, type and amount of intercellular substance and amount of tissue fluid
What are the three embryonic germ layers of epithelium?
Ectoderm, mesoderm and endoderm
2 types of epithelium
Covering/lining tissues
Glandular

What are the functions of epithelium
Protective- against physical, chemical or pathologic a salt, dehydration and heat loss Receptive/sensory Absorption Secretory Lubricates
How many layers in simple epithelium?
One single very delicate layer
Describe simple squamous epithelium
Cells are flat, line the walls of blood and lymph vessels
Describe simple cuboidal epithelium
Cells are cube shaped, lines Intercalated ducts of salivary gland‘s
Describe simple columnar epithelium
Cells are tall and narrow, lines the striated ducts of salivary gland‘s
Describe pseudostratified columnar epithelium
Appears stratified, lines the terminal ducts of salivary gland‘s and lines the upper respiratory tract and parotid papilla
How many layers in stratified epithelium
 several layers thick
 describe stratified squamous epithelium
Cells are flat with several layers
Mostly composed of keratin
NO blood vessels

Describe stratified columnar epithelium
Tall and narrow and several layers thick
 line the pharynx and larynx
What is the deepest layer of stratified squamous epithelium
Stratum germinativum/ Basal layer
Rests on the basement membrane and separates the epithelium from connective tissue
Characteristics of the stratum germinativum
Deepest layer
Highly mytotic
Contains melanocytes
Cells are cuboidal to columnar
Epithelial retes/pegs interdigitate with connective tissue forming a convoluted line
Tonofilaments hold layers of cells together
Layers of epithelium from deepest to outer layer
Stratum germinativum
Stratum Spinosum
Stratum granulosum
 stratum corneum
Describe the stratum Spinosum
Prickle layer
Desmosomes and Tonofilaments are formed on all surfaces
Some mitotic activity in the deepest portion
Melanocyte processes form
Describe the stratum granulosum
Granular layer
Flat diamond shaped cells
Impermeable and can withstand shearing forces and mild acids and bases
*Describe the stratum lucidum
Clear layer, may or may not be present
Found between granulosum and corneum
Thin, flat, few organelles
Describe the stratum corneum
Keratin layer Surface layer, cells are called squames Cells are 14 sided polygon‘s which interlock increasing in permeability No nuclei, cells are filled with keratin Layer desquamates, shedding itself
What is contact dermatitis?
Inflammation of the skin due to contact with an irritant
 causes irritation but not anaphylaxis
What is contact stomatitis
Inflammation of the oral mucosa due to contact with an irritant
Many people are allergic to Esther-based products as well as amides
What are traumatic ulcers
Caused by physical trauma that results in a break between the stratum germinativum and the basement membrane exposing the underlying connective tissue
What are viral ulcers
Caused by a virus that results in a break between the stratum germinativum and the basement membrane exposing the underlying connective tissue
Herpes on the lips and attached gingiva
What are aphthous ulcers
Also known as canker sores
Host mediated ulcers caused by the persons own immune response resulting in a break between the stratum germinativum in the basement membrane and exposing the underlying connective tissue
Describe wound healing
-Remove source of injury
- Clot forms, inflammatory response triggered by WBC‘s as they move toward the injured area
- Clot acts as a guide to form a new surface tissue
- Epithelial cells around the injury migrate in to form a new epithelial surface layer beneath the clot
- After surface is repaired, clot is broken down by enzymes
What layer does basal cell carcinoma form in
Stratum germinativum
What is basal cell carcinoma
Proliferation of basaloid epithelial cells and is caused by exposure to sun usually on the head, neck and middle third of face
May present as a cratered ulcer with a raised border
Most treatable form of skin cancer
What is squamous cell carcinoma, what causes it
Thickening/hyperplasia of the epidermis or oral mucosa
Intraoral causes include tobacco, alcohol, trauma, heat from pipe smoking and nutritional deficiency

Where does squamous cell carcinoma occur
In the germinativum layer
Found in the oral cavity, on the lips and also on all exposed surface at the dermis due to sun exposure
Red or white lesions with irregular, non-demarcated borders. Deadly
Where does malignant melanoma develop from
From free malignant Milana Cytec dysplasia
Neoplasm of epidermal melanocytes
Caused by sun exposure and causes 85% of all skin cancer deaths
Signs of melanoma
Affects individuals with fair complexions
Lesions are asymmetric with irregular borders, variegated color and diameter equal or greater than 6 mm
Found on the back, head, neck, chest, abdomen and extremities
What are the ABC D’s of melanoma
Asymmetry
Borders are ragged, notched or blurred
Color is uneven tan, brown, black, red, white or blue
Diameter is larger than the size of a pencil eraser

Describe intraoral melanoma
Deeply pigmented, may ulcerate and bleed
Favors the maxillary arch and into the vestibule/alveolar ridge
Radial growth patterns will present only on the surface
Vertical growth pattern well include increased size, darker color, nodulation, ulceration and will start to metastasize
How much will your risk of melanoma increase by using tanning beds before the age of 30?
75%
What is the process of tanning?
Granules of melanin are produced by melanocytes
Melanin passes through the melanocytes along processes to the granular layer of the epithelium and is absorbed into the keratin granules

How does endocrine glandular tissue function
Releases internally
Ductless, secretions diffuse into blood and lymph vessels
- thyroid, thymus, hypothalamus
How does exocrine gland dealer tissue function?
Secretes “outside” the body
External, have ducts, secretions are transported via duct system
Salivary, sebaceous, sweat, mammary
What are the general  characteristics of connective tissue
Fewer cells, more intracellular substance and tissue fluid
Major component is collagen
Provides framework that supports epithelium
Transport of nutrients
What are fibroblasts?
Most numerous cell and connective tissue
Produces intracellular substance
Secretes precursors of collagen and elastin
What are mast cells?
Leukocytes
High number in oral mucosa
Increased number in connective tissue of oral mucosa and gingiva
Synthesize heparin and histamine
When they react they release histamines and the heparin allows WBCs to leak into an area
What is heparin?
Anticoagulant synthesized by mast cells
What is histamine?
Induces capillaries to release plasma, synthesized by mast cells
What are adipose cells?
 fat cells
 what are macrophages
Scavenger cells that consume dead cells, foreign bodies and other debris.
Found near small blood vessels in tissues
Types of white blood cells
Leukocytes: neutrophils, eosinophils, basophils
Lymphocytes: B cells, T cells, NK cells and monocytes
Function of plasma cells
 produce antibodies/immunoglobulin
First line of defense to bacteria, viruses and other foreign bodies
Immunoglobulin A (IgA)
Two sub groups:
- Serous in blood
- secretory in saliva, tears and breastmilk
Defend against pathogens in body fluids
IgD
Activates B-cell lymphocytes as antigen receptors
IgE
Hypersensitivity response
IgG
Major immunoglobulin in blood serum and can pass placental barrier for passive immunity in newborns
IgM
Early immune response against pathogens
Describe type one collagen
Most common type in the dermis, bone, tendons
- lamina propria/ oral mucosa, Denton, pulp, cementum, PDL, alveolar bone
What type of collagen is most abundant in dental tissues?
Type 1
Out of all the dental tissues, which one is epithelial?
Enamel
E=enamel/epithelial
All others are connective tissues
Loose connective tissue
Forms membranes of connective tissue called fascia
Attaches structures of the body to one another and provides a protective padding
Contains blood vessels and nerve tissue
Dense connective tissue
Found throughout the body
Regular: tendons, ligaments
Irregular: underlies Epithelium
Reticular: framework for blood vessels and internal organs
Elastin: vocal cord folds
Describe the dermis
Connective tissue proper
Papillary layer of loose connective tissue with Epithelial rete Ridges
Dense/reticular layer of dense connective tissue below the papillary layer
Describe the hypodermis
Connective tissue deep to the dermis
Combination of loose connective tissue and adipose tissue
Features of connective tissue and collagen
Lower number of cells
Increased Intercellular substance and tissue fluid
Major protein is collagen- most abundant proteins in the body and product of a living cell (fibroblasts) most abundant cell of connective tissue
Ex: dentin, cementum, alveolar bone, PDL, pulp
Features of epithelial tissue and keratin
Increased number of cells
Decrease in Intercellular substance and tissue fluid
Major protien is keratin
Second most abundant protein in the body and product of a dying cell (keratocyte) most abundant cell of epithelium
Ex: enamel
