Epithelial Tissues and Glands Flashcards
Epithelial Tissue
Epithelium
Covers body surfaces and lines ducts, hollow organs (tubes in GI, respir., urogenital), and closed body cavities (peritoneal)
- Covering/Lining Epithelium
- Glandular Epithelium
*NO EC Matrix
Connective Tissue
Abundant amount of EC Matrix
Muscular Tissue
Generate force to make body move using stored ATP
Nervous Tissue
Detects changes and stimuli along and outside body then reacts by generating nerve impulses (Action Potential)
Key to maintaining homeostasis
Glandular epithelium
glands are formed by epithelium both in the duct and secretory portions
What are the 6 functions of epithelial tissue/epithelium?
- Secretion (glands, epithelium in GI)
- Absorption (GI tract and SI, absorb material across epithelial lining)
- Filtration (blood-move things into or out of blood)
- Excretion (tube away from body)
- Transport (exo/pinocytosis; materials along surface via cilia, such as respiratory tract)
- Protection (mechanical, chemical, or bacterial; ex. transitional epithelium of urinary system)
SAFE TP
Which characteristics define epithelial tissue?
- Cellularity (well packed, lots of cells, little to no EC matrix)
- Specialized Contacts (cells well packed together, adhesion molecules bind them forming specialized cell junctions)
- Polarity
- free or apical surface/pole/domain
- lateral surface/domain
- basal surface/pole/domain - Supported by Connective Tissue - lamina propria, basal membrane
- Avascular, but Innervated (relies on connective tissue underneath)
- Regeneration (easily damaged in outer surface of skin, lining of GI/respiratory; rapid cell division repairs quickly)
Epithelial tissue is avascular and contains few nerve fibers, True or False?
FALSE
Epithelium is avascular but INNERVATED
-epithelial tissue is supported structurally and functionally by the underlying CONNECTIVE tissue, but is innervated with lots of nerve fibers (needed to pick up info about environment)
Describe the lamina propria
connective tissue that is part of a mucous membrane, supports epithelial tissue
What is the apical domain/pole/surface?
the area of the cell facing the lumen of closed body cavity, often has cilia or other specializations (microvilli)
-toward free surface/external environment or lumen of tube/cavity
What is the purpose of microvilli vs cilia as associated with epithelial tissue polarity?
microvilli on the apical domain of epithelium help to increase the surface area
cilia move stuff across surface
What is the lateral domain?
toward cell right next to it, this is where a lot of specialized contacts occur (cellular junctions holding them together)
Describe the basal domain/surface
Where epithelium rests/lies on connective tissue
between connective tissue and epithelium is the basal membrane
-contains hemidesmosome and focal adhesion junctions
Morphology is used to define the subclasses of epithelium, True or False?
TRUE
cell number and cell height/shape variation are used to define the subclasses
_# cells___ _height/shape__ epithelium*
(3 part name or its incorrect)*
Number of cell layers are defined by which 3 classifications?
1) Simple
2) Stratified
3) Pseudostratified
Cell height/shape is classified via which 3 variations?
1) Squamous
2) Cuboidal
3) Columnar
Sometimes another name can be added based on any specializations at the apical surface of the cell (ex. ciliated) or at the apical surface of the tissue (ex. keratinized). This name would go in front of the 3 name tissue classification, True or False?
TRUE
In simple epithelium, there is only one layer of cells, and therefore all cells are on the basement membrane, True or False?
TRUE
Describe stratified epithelium
2+ layers of cells, only the bottom layer is on the basement membrane
Squamous
very flat, cytoplasm flat and then perk up for nucleus then flatten again, nucleus bulges toward free surface, WIDTH > HEIGHT
cells very flattened near top if stratified
Cuboidal
As tall as they are wide (width=height)
nucleus circular center
Columnar
Taller than they are wide
Height> Width
elongated nucleus usually
Is ciliated or nonciliated simple columnar epithelium more common in the body?
NONCILIATED
GI tract, gallbladder
With stratified squamous epithelium, what question should you immediately ask?
find out if keratinized or nonkeratinized:
- at surface, dead, slough off for protection (nuclei gone, bag of keratin basically)
- keratinized only in skin
esophagus and vagina: nonkeratinized stratified squamous
transitional epithelium is also known as _____
Urothelium
Urothelium
(transitional epithelium)
associated with urinary system lining a lot of passageways associated with it, minor kelacis of kidney down to urethra, ureters, urethra, renal pelvis, etc
-known as transitional cause it will CHANGE SHAPE on you, when passageway is empty (like bladder), you can see multiple layers of cells and cells at surface have puffy appearance (called umbrella cells bc of it, sometimes have 2 nuclei as well)
as bladder stretches, surface cells become FLAT, ie transitioning
columnar should be flat across surface
when distended: squamous at surface
-kidney to urethra
Pseudostratified columnar epithelium is mostly _______
need to say if ciliated and non ciliated form
mostly in CILIATED form we’ll see it (typically respiratory tract)
Ciliated: trachea, upper respiratory tract
(propulsion of mucous)
Nonciliated: male’s sperm carrying-ducts, epididymis, ducts of larger glands
Simple columnar epithelium is mostly _______
NONCILIATED
just simple columnar, don’t need to say ciliated or non ciliated
Describe the structure and function of Simple Squamous Epithelium. Where is it found in the body?
ENDOTHELIUM, MESOTHELIUM
Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm (the simplest of the epithelia) great for tissue diffusion, secretion, absorption, transfer
Function:
- allows passage of materials by diffusion and filtration in sites where protection is NOT important
- secretes lubricating substances in serosae
Location:
-kidney glomeruli (Bowmans capsule) , air sacs of lungs, lining of heart, blood vessels, and lymphatic vessels; lining of ventral body cavity (serosae)
In the closed cavities of body like pleural, peritoneal, and pericardial cavities, the epithelium lining them is _______, but you call it mesothelium
simple squamous epithelium (in body cavity= mesothelium)
associated w/ a serous membrane (part of closed body cavity)
Ex: 3 cavities; peritoneum, pericardial, pleural
Endothelium is also known as
Simple Squamous Epithelium lining all blood vessels and the heart, as well as lymphatic vessels
-formed by embryonic mesoderm
Simple Cuboidal Epithelium
Single layer of cubelike cells with large, spherical central nuclei
Function: secretion and absorption (not very thick)
Located in:
- Kidney tubules
- ducts (pancreas) and secretory (thyroid) portions of small glands
- ovary surface
- anterior surface of capsule of lens of eye
- found exiting glomerulus
Simple Columnar Epithelium
Single layer of tall cells with round to oval nuclei; some cells have cilia
- layer may contain goblet cells (mucus-secreting unicellular glands)
- nuclei at basal surface, usually more stretched out nucleus but still by basal side
Function:
- absorption
- secretion of mucus, enzymes and other substances
- ciliated type: propels mucus or reproductive cells
Location:
- Nonciliated (Majority in body):
- lining most of digestive tract (stomach to anal canal), gallbladder, and excretory ducts of some glands - Ciliated:
- lining small bronchi
- uterine tubes
- some regions of uterus
- some paranasal sinuses
- central canal of spinal cord
- ventricles of brain
Describe the difference between ciliated and nonciliated simple columnar epithelium
The majority of simple columnar epithelium is nonciliated in the body
nonciliated:
- have much shorter MICROVILLI that don’t move (are immotile)
- contains goblet cells (exocrine gland)
- stomach down to anus (GI tract), ducts of many glands, gallbladder
- secretion of mucous and absorption
ciliated:
- taller than wide, elongated nucleus
- respiratory tract, uterine tube, spinal cord, uterus, paranasal sinuses
- move mucus and secretion cells by cilliary action
- small bronchi, uterine tubes
Stratified Squamous Epithelium
Thick membrane composed of several cell layers
- Basal cells are cuboidal or columnar and metabolically ACTIVE (mitosis: produce the cells of the more superficial/surface layers)
- APICAL/Surface cells are flattened (squamous):
- Keratinized: when surface cells are full of keratin and DEAD; no nuclei (epidermis, outer surface thick skin)
- Nonkeratinized: still active, contain nuclei (vagina, esophagus)
Function: protection
*Look at APICAL SIDE aka FREE SURFACE of tissue
surface cells: stratified, squamous -> immediately think PROTECTION (multiple layers protecting underlying) -> immediately determine if KERATINIZED or not
How common is stratified cuboidal epithelium? Where is it located?
RARE in human body, shows up in ducts or transitions between tissues
Two or more layers of cells in which apical layer cells are cube-shaped; protection and limited secretion and absorption
Location:
- ducts of adult sweat glands
- esophageal glands
- part of male urethra
Describe stratified columnar epithelium as well as its function and location
several layers of irregularly shaped cells, ONLY APICAL layer has columnar cells (at surface they are taller than they are wide)
Location:
- lining part of urethra
- large excretory ducts of some glands (esophageal glands)
- small areas in anal mucous membrane
- part of the conjunctiva of eye
Function: protection and secretion
RARE
Pseudostratified columnar epithelium
actually SIMPLE: SINGLE layer of cells of differing heights (but all touching basement membrane), some don’t reach free/apical surface
- nuclei seen at different levels
- may contain goblet cells (exocrine, mucous) and bear cilia
Function: secretion, particularly mucus
-propulsion of mucus by ciliary action
Location:
- nonciliated: male’s sperm-carrying ducts (epididymis to vas deferens) and ducts of large glands
- ciliated: lines trachea, most of upper respiratory tract
Goblet cells
exocrine gland
nucleus near base, release mucigen to mix with water and make mucous
- pseudostratified columnar epithelium
- also in simple columnar epithelium
- Pseudo is simple too technically
Transitional epithelium (urothelium) resembles which two epithelial types? Where is it found and what is its function?
Both stratified squamous and stratified cuboidal epithelia; nice and puffy, sometimes more than one nucleus associated
Basal cells: cuboidal or columnar
Surface/Apical cells: dome shaped (umbrella) or squamous like (depends on degree of organ stretch)
Function: stretches readily and permits DISTENSION of URINARY organ by contained urine
Location: Lines ureters, bladder, and part of urethra
In transitional cells, the apical layer cells are _____ when stretched and _____ when relaxed
stretched: squamous
relaxed: cuboidal
* like stretching a cube of jello vs letting it sit still