Epithelial Flashcards
What are cells?
Basic building block of tissues
What is the hierarchy of organization of cells?
Cells then Tissue then Organ then Organ system
What is tissue?
A group of closely associated cells that are similar in structure and perform related functions
What are the types of tissue?
4 types. Muscle, connective, epithelial, and nervous
What is an organ?
A structure with a particular function that is made up of ALL 4 tissue types
What is an organ system?
A group of organs related in function (for example the gastrointestinal system)
What is the primary function of epithelial tissue?
Covering/Protecting
What is the function of connective tissue?
Support and connections
What is the function of muscle tissue?
movement
What is the function of nervous tissue?
regulation and control
What does epithelium typically line?
Covers a body surface or lines a body cavity
What is the ectoderm?
Covers the external surfaces of body
What type of epithelium covers the external surfaces of the body?
Ectoderm
What is the mesothelium?
Lines the internal cavities of the body (e.g. pleural, peritoneal, and peroneal surfaces)
What type of epithelium lines the internal cavities of the body?
The mesothelium
What is the endothelium?
Lines tubes (vascular and lymphatic vessels)
What type of epithelium lines tubes?
Endothelium
What are epithelial organs called?
Glands
What are the two types of glands? Differences?
Exocrine (ducted) and endocrine (ductless)
What epithelial glands are ducted?
Exocrine
What epithelial glands are ductless?
Endocrine
What are the 3 major functions of epithelium?
Protection, border tissue, glandular secretions
Border tissue has what three functions?
absorption, secretion, ion transport
Glandular secretions have what function?
Lubrication
Special functions of epithelium are?
Sperm and eggs are derived from epithelium
The space that epithelium lines is called?
The lumen
What separates epithelial cells from connective tissue?
The basement membrane
What are the two major regions/portions of epithelial cells?
Apical and basement
Describe the separation of epithelial cells
Very packed. Minimal extra-cellular space
What sort of specialized contacts do epithelial cells have?
Structural and adhesive (tight/adherens junctions) and functional (gap junctions)
What is the polarity of epithelial cells?
Regions are specialized into apical and basal surfaces. I.e. ER is in basal region and vacuoles are in apical region
T or F: Epithelial cells are non-vascular
T
How do epithelial cells receive nutrients?
Diffusion from capillaries
T or F: Capillaries transverse the basement membrane to provide nutrients to epithelia?
F (doesnt cross)
What are the regenerative capacities of epithelial cells?
Lost cells are very quickly replaced by cell division
T or F: Nerve endings cross the basement membrane into epithelial tissue
F (separated by basement membrane)
What are the two possible apical features of epithelium?
Microvilli and Cilia
What are microvilli?
Fingerlike extensions of plasma membrane
Where are microvilli typically located and what are their functions?
Abundant in epithelium of small intestine and kidney. Increase the surface area across which small molecules enter
What are cilia?
Highly motile extensions of apical surface membrane
What is an axoneme?
A set of microtubules in a 9+2 arrangement that allows cilia motor function
What is the function of cilia?
Coordinated movement to move surface fluids toward the lumen
What are the 6 characteristics to look for in regards to epithelium?
Proximity to lumen, presence of basement membrane, closely packed cells, polarity, non-vascular, and sometimes presence of microvilli/cilia
What are the two types of epithelial layers?
Simple - single layer of cells
Stratified - more than one layer of cells
What are the three shapes of epithelial cells?
Squamous - cells are wider than tall (plate like)
Cuboidal - cells are tall as they are wide like cubes
Columnar - cells are taller than they are wide, like columns
What two characteristics are used to define epithelial tissue?
Number of layers and shape of cells
What is the function of simple, squamous epithelium?
Passage of materials by passive diffusion and filtration
Where are simple squamous epithelium tissues found?
Aveloi of lungs and lining of blood and lymphatic vessels (capillaries covering are termed endothelium)
What type of epithelium covers lymph, blood vessel, and lung aveoli?
Simple squamous
T or F: Simple squamous tissue is one cell thick
T
What is the function of simple cuboidal cells?
Secretion and/or absorption
Simple cuboidal epithelium are found where?
Kidney tubules, secretory portions of glands
What organelles are common in simple cuboidal epithelium?
Lots of mitochondria to provide energy for pumping function
Kidney tubules and secretory portions of glands are covered in what type of epithelium?
Simple cuboidal epithelium
T or F: Simple columnar typically have microvilli or cilia at their apical surface
T
What is the function of simple columnar epithelium?
Absorption. Secretion of mucous, enzymes. Cilia propels mucous in oviduct
Where are simple columnar epithelium found?
Most of GI and uterus
GI and uterus are covered in what type of epithelium?
Simple columnar epithelium
The epididymis is covered in what type of epithelial?
Simple columnar
What is the function of stratified squamous epithelium?
Superficial cells are squamous in shape ad deep cells appear to be cuboidal or columnar. Thickest epithelial tissue to adapt for protection from abrasion
What is the thickest type of epithelium?
Stratified squamous
What is the basal to apical characteristic of stratified squamous epithelium?
Columnar or cuboidal at deepest layer and becomes squamous on the superficial layer
What are the two types of stratified squamous epithelium?
Keratinized or non-keratinized
Keratinized tissue are morphologically distinct from non-keratinized tissue because?
Keratinized tissue outer cells lose nuclei and organelles. Non-keratinized have organelles and nuclei in outer layer of cells
Keratinized stratified squamous epithelium is found where?
Skin (dry)
Non-keratinized stratified squamous epithelium is found where?
Oral cavity, esophagus, vagina
T or F: Stratified cuboidal epithelium is more robust than squamous stratified epithelium
T
What is the morphology of stratified cuboidal epithelium?
Double layer of cube like cells
What is the function of stratified cuboidal epithelium?
Protection of glandular surfaces
Where is stratified cuboidal epithelium found in the body?
Ducts of sweat, mammary, and salivary glands
Describe stratified columnar epithelium
Single layer of column like cells o top of a layer of polyhedral/cuboidal like cells.
VERY UNCOMMON
What is the function of stratified columnar epithelium?
Transitional
Where is stratified columnar epithelium found?
Transition between stratified squamous and simple columar. Conjunctiva of eye. Certain large excretory ducts. Male urethra (parts).
Describe transitional epithelium
Several layers of cells. Shape varies with distention of tissue. Superficial cells are DOME SHAPED and may be binucleated
What is the function of transitional epithelium?
Accommodate distention of muscular wall and secretion of protective glycoproteins
Where is transitional epithelium found?
Bladder
Describe pseudostratified epithelium
Nuclei at varied heights within the cell. Gives a false impression of stratification. Most have cilia and microvilli on apical surface. All cells touch the basement membrane, but only some reach the lumen.
Pseudostratifed epithelium serves what function?
Protection, secretion of mucous, and movement of mucus by cilia
Where is pseduostratified epithelium found?
Upper respiratory tract, kidney tubules, and secretory portions of glands
In addition to covering body surfaces and lining body cavities, what does epithelium additionally form?
Parenchyma of glands
What is parenchyma?
Functional (secretory) portion of a gland (e.g. nephrons in kidneys)
What is stroma?
Structural tissue in glands
What are the three steps in the development of glands?
Epithelium thickens. Epithelial cord penetrates connective tissue. Invagination either remains patent (exocrine) or closes off (endocrine)
What is the function of exocrine glands?
Ducts carry products of exocrine glands to the epithelial surface
Give examples of exocrine glands
sweat and sebaceous glands of skin. mucous secreting glands of digestive system like salivary glands and liver and pancreas glands (bile duct).
What is the function of endocrine glands?
Ductless glands comprised of epithelial tissue that dump their substances directly into bloodstream (i.e. to EC space)
Give examples of endocrine glands
Adrenal, thyroid, pancreatic islets
Endocrine glands produce what kind of molecules?
Hormones
What are the two types of exocrine glands?
Single cell and multi-cell
What are goblet cells?
Single cell exocrine glands in the GI and respiratory tract. Do not stain in h&E
What are the branching patterns of the ducts in exocrine glands?
Simple (unbranched) or compound (branched)
What are the two shapes of secretory units in exocrine glands?
Tubular or acinar (grabes on a vine). Also tubloacinar which is a mix.
What are the two types of secretory product of exocrine glands?
Mucous (thick) versus Serous (watery)
What does serous product of exocrine glands contain?
Digestive enzymes and stains DARK in H&E
What is mucous from exocrine secretory glands comprised of?
Usually light on an H&E stain and carbohydrate rich (PAS stain?).
T or F: Serous and mucus fluid from exocrine glands are usually in separate acini?
T, but not always
What are the three modes of glandular secretion?
Eccrine, apocrine, and holocrine
What is eccrine glandular secretion?
Also called merocrine and only the secretory product is released
What is apocrine glandular secretion?
Some cytoplasm is released along with the secretory product (sloughed off)
What is holocrine glandular secretion?
Entire cell is secreted and is disintegrated
