Epithelium

Langerhans Cells

Derived from bone marrow and is a type of dendritic cell (immune system). Constantly checking the oral mucosa.

Tight Junctions

Highly selective barrier limits and prevents diffusion of substances between epithelial cells

Desmosomes

Promote mechanical strength and resist shearing forces and promote structural organization of epithelial sheet

Hemidesmasome

Attach epithelium to underlying basal lamina

Mucosa

Epithelium + Lamina propria

Lamina propria

Connective tissue under epithelium

Submucosa

Connective tissue under lamina propria

Epidermis

Outer covering epithelium

Dermis

Underlying CT for outer covering epithelium

Skin

Epidermis + Dermis

Apical specializations

Microvilli, motile cilia, sensory cilia

Microvilli

Increase surface area to facilitate absorption of luminal contents

Motile cilia

Wave back and forth to move fluid along surface

Sensory Cilia and Microvilli

Membrane extensions for detection of movement or chemicals (taste buds, olfactory receptors, and auditory hair cells)

Adherence Junctions

Promote attachment, as well as polarity, and morphological organization

Gap Junction

Provide avenues for communication between cells

Paracellular

Between two cells

Transcellular

Inside cell and out

Basal lamina

A meshwork of extracellular matrix proteins allows signaling molecules to move around under epithelial cells. Provides crucial signals to overlying epithelium.

Stem Cells

Proliferative cells along the basal lamina continuously reproduce tissue (differentiate into diff. cells) with the capability of renewal. Regulation is key

Transit Amplifying Cells (TACs)

Stem cell intermediate that create a lot of different cells

Regulation of Stem Cells

Rates of division and spatial organization within tissues

Wound Healing

Response to tissue damage, tissue invaded by elements of immune system (neutrophils, macrophages and fibroblasts), which up regulate basal cell division and tissue reconstruction

Oral Wound Healing

Infiltrating cells in the oral mucosa are anti-inflammatory, which is a key factor in reducing scarring in contrast to facial epithelium

Cell Division

Basal cells attached to the basement membrane are usually capable of generating new epithelial cells replacing other cells

Epithelial Specializations

Teeth, Taste Buds

Covering Epithelium

Skin and Oral Mucosa

Glands

Secretory Epithelium

Types of Epithelium

Epithelial Specializations, covering epithelium, glands

Tooth Development

Complex signaling interaction between epithelial cells and underlying mesenchymal cells. Ameoblasts and odontoblasts form in adjacent layers at the site of interaction between epithelium and mesenchyme

Molecular signals in Tooth Development

Molecular signals from the epithelium direct the differentiation and specialization of the underlying mesenchyme. Reciprocal signals from the mesenchyme then direct changes in the overlying epithelium.

Mesothelium

Lining of body cavities

Endothelium

Lining of blood vessels

Urothelium

Lining of urinary tract

Respiratory Epithelium

Lining of respiratory tract

Simple Squamous Epithelium

Lung alveoli, blood vessels (endothelium), body cavity (mesothelium)

Stratified Squamous Epithelium

Lines much of the oral cavity with thickness of keratinized layer of flattened dead cells varies on location

Keratinized

Many dead cells

Nonkeratined

Few dead cells

Simple Cuboidal Epithelium

Kidney collecting tubule, and salivary glands close to acini (secretory cells, base)

Stratified Cuboidal Epithelium

Eccrine sweat gland duct, parotid salivary gland, late ovarian follicle

Simple Columnar Epithelium

Uterine tube, gall bladder, salivary glands (towards surface of epithelium)

Stratified Columnar Epithelium

Sublingual gland, salivary gland duct

Pseudo-stratified Columnar Epithelium

Pharynx (nuclei at different depths but cells stretch full height of epithelium)

Exocrine Gland

Secreting outside with duct

Endocrine Gland

Release contents into blood

Merocrine gland (salivary gland)

Secretory vesicles release into external surface

Halocrine Gland

Cells form at the base, disintegrate, and explode into ducts, more lipid-rich.

Apocrine Gland

Fracturing apical side and then released into duct for secretion

Types of Exocrine Gland

Merocrine, halocrine, apocrine

Exocrine Gland Secretion Types

Serous, mucous, sebum

Serous

Water fluids rich in enzymes, help break down carbs (saliva), parotid gland

Mucous

Thick, viscous, and rich in mucin, acts as a lubricant and protects the oral cavity.

Sebum

Thin, oily, lipid rich (from sebaceous glands)

Protection

Keeping out bacteria and water in

Selective Transport

Transport metabolites into body and secreting products into lumens and blood stream

Communication

With other cells/tissues

Biochemical Modification

Hepatocytes or ductal cells of salivary glands

Developmental Dynamism

Continuous/flexible development and cell replacement. Teeth form from an interaction between epithelium and mesenchyme

Special Sensation

Taste, olfactory, auditory and vestibular receptors are specialized epithelial cells

Thyroid Gland

Simple cuboidal to squamous epithelium

Ectoderm

Epidermis and associated glands (sweat, salivary, mammary, and sebaceous

Mesoderm

Mesothelium (lining of body cavity), endothelium (lining of blood vessels)

Endoderm

Respiratory tract, GI tract and associated glands (liver, pancreas), urinary bladder