Cell and Molecular Biology Lecture 8: Histology of Epithelial Tissue

How many different types of cells are there in the human body?

200

What are the four basic types of tissues?

Epithelial, connective, muscle, nervous

What are the two forms of epithelial tissue?

Epithelia and glands

What are the three embryonic germ layers?

Ectoderm, endoderm, mesoderm

Epithelia is derived from _____ embryonic germ layers

All 3

What is the embryonic origin of the oral and nasal mucosae?

Ectoderm

What is the embryonic origin of the cornea?

Ectoderm

What is the embryonic origin of epidermis?

Ectoderm

What is the embryonic origin of skin glands?

Ectoderm

What is the embryonic origin of the mammary glands?

Ectoderm

What is the embryonic origin of the liver?

Endoderm

What is the embryonic origin of the pancreas?

Endoderm

What is the embryonic origin of the respiratory and gastrointestinal tracts?

Endoderm

What is the embryonic origin of the kidneys?

Mesoderm

What is the embryonic origin of the reproductive systems?

Mesoderm

What is the embryonic origin of the circulatory system?

Mesoderm

What is the embryonic origin of the mesothelium of body cavities?

Mesoderm

What separates the epithelia from the connective tissue?

Basal lamina

What synthesizes basal lamina?

Epithelia

Epithelial tissue is _____

Avascular

Adjacent supporting connective tissue through its capillary beds supplies nourishment and oxygen to epithelia via _____

Diffusion through basal lamina

What are the sheets of contiguous cells that cover the body on its external surface and line the body on its internal surface?

Epithelia

What originated from invaginated epithelial cells, synthesizes/stores macromolecules as granules?

Glands

What are the types of glands?

Exocrine and endocrine

What are the 5 functions of epithelial tissue?

Protection, Transport, Secretion, Absorption, Selective Permeability, and Sensation

The structural basis for classification of epithelia is based on the number of __________ between basal lamina and free surface and by the ___________ of cells

Cell layers; Morphology

What is simple epithelium?

1 layer

What is stratified epithelium?

More than 1 layer

What are the different morphologies of epithelial cells?

Squamous (flat), cuboidal, columnar

What are the other two distinct types of epithelia?

Pseudostratified, transitional

What type of epithelia is a single layer of flat cells with a centrally placed bulging nucleus?

Simple squamous epithelium

Where is simple squamous epithelium found?

Lining pulmonary alveioli and blood/lymph vessels

Which type of epithelia provides a square profile when cut perpendicular to the surface and has a centrally placed nucleus?

Simple cuboidal epithelium

Where is simple cuboidal epithelium found?

Ovaries, kidneys

Which type of epithelia is tall, rectangular cells in a longitudinal section with ovoid nuclei located at the same level in the basal half of the cell?

Simple columnar epithelium

Where is simple columnar epithelium found?

Digestive tract, uterus, oviduct

Which type of epithelia is composed of several layers of cells with the deepest layer in contact with the basal lamina?

Stratified squamous (non-keratinized) epithelium

Where is stratified squamous (non keratinized) epithelium found?

Mouth, oral pharynx, esophagus

Which type of epithelia is composed of dead cells with the nuclei and cytoplasm replaced with keratin?

Stratified squamous (keratinized) epithelium

Where is stratified squamous (keratinized) epithelium found?

Epidermis

Which type of epithelia is composed of two layers of cuboidal cells?

Stratified cuboidal epithelium

Where is stratified cuboidal epithelium found?

Sweat glands

Which type of epithelia is composed of a superficial layer of columnar cells with a cuboidal deeper layer in contact with basal lamina?

Stratified columnar epithelium

Where is stratified columnar epithelium found?

Conjunctivae of eye

Which type of epithelia is erroneously believed to be in transition between stratified columnar and stratified squamous?

Transitional epithelium

Where is transitional epithelium found?

Bladder

Which type of epithelia has all cells in contact with basal lamina and only some cells reaching the surface of the epithelium?

Pseudostratified epithelium

Where is pseudostratified epithelium found?

Nasal cavity and trachea

Where does the apical domain face?

Lumen

The basolateral domain's basal component is in contact with _____

Basal lamina

Both apical and basolateral domains are separated by _____ that encircle the apical aspect of the cell

Tight junctions

What are the three apical domain specializations?

Microvilli, cilia, flagella

Which apical domain specialization is involved in absorption and transport?

Microvilli

Which apical domain specialization is involved in moving mucus?

Cilia

Which apical domain specialization (for spermatazoa) is involved in movement towards eggs?

Flagella

What forms a belt junction that prevents movement of proteins and water molecules? It is the most apical lateral membrane specialization

Zonula occludens

What is the lateral membrane specialization that assists adjoining cells to adhere to one another? It encircles cell and is from the basal to zonula occludens

Zonula Adherens

Zonula occludens and zonula adherens form a _____ around the cell apex

Continuous ribbon

What helps to resist shearing forces, is weld-like, and arranged on lateral sides of plasma membranes?

Macula adherens/Desmosome

What consists of 6 closely packed connexins and mediates intercellular communication?

Gap junctions

What is the process of increasing surface area available for transport in the basal surface?

Basal plasma membrane enfolding

What attaches epithelial cells to underlying basal lamina and facilitates transport?

Hemidesmosomes

Epithelial cells exhibit a _____ turnover rate

High

Turnover is related to _____ and _____

Location, Function

What is the renewal period of the epidermis?

28 Days

How often are the cells lining the small intestine replaced?

4-6

Desmosomes and gap junctions make _____

Spotlike plaques

What are the motile, hair-like projections that emanate from the surface of certain epithelial cells?

Cilia

What is the disorder that results in the binding of autoantibodies to desmosomal proteins, disrupting cell adhesion and results in widespread blistering and loss of extracellular fluid?

Pemphigus vulgaris

Mutations in connexin genes cause which skin disease?

Erythrokeratodermia variabilis

What is the transformation of pseudostratified ciliated columnar epithelium of bronchi of heavy smokers into stratified squamous epithelium called?

Squamous metaplasia