Types of Epithelia Flashcards
Surface epithelia form __ of cells
sheets
Epithelia lining glands and their ducts are derived from __ and surround ___
surface epithelia
A central lumen
Blood vessels are lined by ___
endothelium (flattened)
Name the three types of celomic body cavities
- pericardial
- pleural
- peritoneal
Types of epithelia
- simple (& 3 subtypes)
- stratified (& 3 subtypes)
* stratified epithelial cells are described according to the height of cells in the __ layer - (the other one)
- simple squamous, cuboidal, columnar
- stratified squamous, cuboidal, columnar; apical/outermost
- pseudostratified
Stratified epithelial cells are described according ot the height of cells in the apical/outermost layer.
Types of glands
- __ cellular (2)
- s__ / c__
- e__ / e__
- unicellular
- multicellular
- simple
- compound
- exocrine
- endocrine
Types of secretion (3)
- serous
- mucous
- seromucous
Mechanisms of secretion (3)
- merocrine (exocytosis)
- apocrine (decapitation)
- holocrine (apoptosis)
Acinar gland
Definition and examples
A part of the exocrine gland (berry-shaped termination)
Ex. Alveolar sac, pancreatic duct
Acinous/acinar (L. = grape)
Alveolar (L. = small cavity)
Apocrine secretion
* is a type of (1) secretion
* by (2) of the (3) part of the cell membrane
* (4) and (5) released with (6)
* Ex. Mammary glands secrete proteins by the (7. apocrine/merocrine/holocrine) mechanism.
The lipid components of milk are released by (8. apocrine/merocrine/holocrine) secretion.
- rank re: severity of cell damage versus other 2 types of secretion
- Exocrine
- Decapitation
- Apical
- A portion of the cytoplasm
- A portion of the cell membrane
- Secretory product
- Merocrine
- Apocrine
Apocrine secretion is a type of exocrine secretion. It occurs by decapitation of the apical part of the cell membrane. A portion of the cytoplasm and cell membrane are also released with the secretory product.
Mammary glands secrete proteins by the merocrine mechanism.
The lipid components of milk are released by the apocrine mechanism.
- Bud secretions through plasma membrane produce membrane-bound vesicles in lumen. The apical part pinches off and enters the lumen.
Merocrine
Basement membrane
- name its 4 major proteins
- the proteins form a __(structural feature)__
Basement membrane is mostly composed of the following 4 proteins
1. Type IV collagen
2. laminin
3. heparan sulfate
4. proteoglycans,
And other proteins that form a fibrillar meshwork
Columnar epithelial cells
* are (1) than they are (2)
- Taller
- Wide
Columnar epithelial cells are taller than they are wide.
Simple versus Compound gland
- re: duct type
- example (1 each)
Simple gland
* unbranched ducts
Ex. Dermal sebaceous gland
Compound gland
* branched ducts
Ex. Ducts and secretory acini of pancreas
Cuboidal epithelial cells
- are (1) in height and width
- are (2) shaped in vertical section
- Equal
- Square-shaped
Cuboidal epithelial cells are equal in height/width and are square-shaped in the vertical section.
Ex. cuboidal epithelium lining the kidney tubules transport salt and water from the lumen back to the bloodstream through the interstitial space.
Epithelia are (avascular or vascular). The blood vessels that nourish the epithelium are located in \_\_\_\_.
Epithelia are avascular.
The blood vessels that nourish the epithelium are located in the subjacent connective tissue.
Glands
* single cells and/or groups of cells? (1)
Endocrine versus exocrine glands
- definitions: (2)
- unicellular and/or multicellular?: (3)
- simple and/or compound glands?:
- tubular and/or acinar glands
- 2 types of secretion:
- 3 modes of secretion:
- Both single cells and groups of cells
- Endocrine: target surrounding interstitum to enter the blood;
Exocrine: target organ/body surface via ducts
Endothelium
Lines blood vessels only; a type of simple squamous epithelium
Goblet cell: define
* uni- or multi-cellular?
Goblet cells are pale-staining unicellular mucous glands.
Holocrine secretion: (1. define, how much cell content secretion)
- example: (2)
- to replace lost cells, (3) at the (4) divide
- rank versus other 2 types of secretion / damage to cell
- Holocrine secretion is achieved by apoptosis of the secreting cell and releases ALL cell contents
- sole example: sebaceous glands
- stem cells at 4. basal lamina divide to replace lost cells)
Merocrine
Merocrine secretion * secretion by _(1)_ Ex. How _(2)_ cells release their _(3)_ secretions Ex. How _(4)_ cells release _(5)_ * only _(6)_ is released
- rank versus other 2 types of secretion / damage to cell
- Exocytosis
- Goblet cells
- Mucous secretions
- Pancreatic acinar cells
- Zymogens
- Secretory vesicle products
Merocrine secretion
* secretion by exocytosis
ex. goblet cells release mucous secretions
Ex. Pancreatic acinar cells release zymogens
* only secretory vesicle products are released
Acini: serous units
Mesentery: define
A fold of membrane that attaches the intestine to the abdominal wall and holds it in place. It is part of the peritoneum.
Mesothelium: define
The mesothelium is a layer of simple squamous epithelial cells that line the pleura (thoracic cavity), peritoneum (abdominal cavity including the mesentery), mediastinum, pericardium (cardiac sac).
Mucous secretion
- a type of (1. apocrine/merocrine/holocrine) secretion
- Ex. (2) cells secrete mucous and are (3. Pale/dark) staining
- Merocrine
2. Goblet cells are 3. pale-staining unicellular mucous glands.
Myoepithelial cells: define
Myoepithelial cells comprise a thin layer of glandular epithelia above the basement membrane and below luminal cells.
They may have actin which contracts and expels exocrine gland secretions (ex. Sweat, mammary, lacrimal (tear), salivary glands).
They proliferate rapidly during wound healing.
They exist in the endoderm or ectoderm.
Simple epithelium versus stratified epithelium
- how many cell layers are in each?
- functions: simple (2), stratified (1)
- examples: simple (6), stratified (5)
Simple epithelium
* 1 cell layer
* these tissues that don’t have a lot of wear and tear
* functions: absorption and secretion
Examples include
* blood vessel endothelium
* mesothelium of celomic cavities
* Bowman’s capsule lining the golmerulus in nephrons
* distal and proximal convoluted tubules (kidney) (DCT/PCT)
* small intestine
* lung alveoli
Stratified epithelium * > 1 cell layer * function: handle lots of wear and tear Examples include * skin * oral cavity * esophagus * anal canal * vagina
Serous secretion
* occurs by serous glands which produce (1) secretions
- Watery
* Serous glands of the pancrease have watery secretions
Epithelial cells: absorption
The (1) of the (2. Organ) absorbs nutrients from the lumen
- Epithelial lining
- Small intestine
The epithelial lining of the small intestine absorbs nutrients from the lumen
Cells secrete products for (1. nearby or distal) utilization.
This includes the secretion of (2) by goblet cells throughout the (3).
- Nearby
- Mucus
- Intestinal tract
Cells secrete products for nearby utilization.
This includes the secretion of mucus by goblet cells throughout the intestinal tract.
Transitional epithelium (or (1)) (or (2))
* is found only in the (3)
Functions
* (4. 2 functions) to accommodate changes in volume of (5), especially the (6).
* (7. 2 more functions): prevent dilution of concentrated urine
* in the relaxed (nondistended) state, this epithelium has surface cells with a (8) appearance and are often (9. uni/bi/multi)nucleate
* they are also called (2) because their (10. Apical/basal) extensions penetrate between other cells
- Urothelium
- Umbrella cells
- Urinary system
- Stretching (distension) and contraction
- Urinary organs
- Urinary bladder
- Protection against toxic urine and resistance to diffusion of water
- Dome-like
- Bi-nucleate
- Basal
Transitional epithelium (or urothelium) (or umbrella cells) are found only in the urinary system.
Functions include stretching/distension and contraction to accomodate changes in the urinary organ volume, especially the urinary bladder.
They also protect against toxic urine and are resistant to H2O diffusion to prevent dilution of concentrated urine.
In the relaxed (nondistended state), transitional epithelium has surface cells with a dome-like appearance and are often bi-nucleate.
They are also called umbrella cells because their basal extensions penetrate between other cells.
Tubular gland versus saccular glands
- how well does each retain its shape?
- what is its shape?
Tubular gland
- maintains tube shape
- simple (large intestine), coiled (sweat gland), compound (pyloric glands of stomach)
Saccular gland
- sac has enlarged lumen (cavity)
- simple or compound
- ex. Thyroid, mammary gland, salivary gland, esophagus, lungs (alveoli)
Umbrella cells
- 2 other names: (1)
- where are they?: (2)
- Urothelium, transitional epithelia
2. Urinary system
Stratified squamous epithelium
* is found (1. internally and/or externally?)
* 2 classifications: (2) or (3)
This is a misnomer: all epithelial cells have (4) filaments.
- Internally AND externally
- Keratinizing
- non-keratinizing
- Cytokeratin
Stratified squamous epithelium is found internally AND externally and is either keratinizing or non-keratinizing.
This is a misnomer. All epithelia have cytokeratin filaments.
Stratified squamous keratinizing epithelium (SSKE)
- in thick (ex. (1) and (2)) and thin (ex. (3)) skin
- has a layer of dead tissue called the (4) on the most (5. apical/basal) surface of the tissue.
(4) consists of squamous epithelial cells that have undergone (6), leaving behind only a (7)-rich and filled dead cell layer which doesn’t have (8) or _(9).
- Soles
- Palms
- Most of epidermis
- Stratum corneum
- Apical
- Apoptosis
- Keratin
- Nuclei
- Organelles
Stratified squamous keratinizing epithelium (SSKE)
- is in thick (soles/palms) and thin (most of epidermis) skin
- has a layer of dead tissue called the stratum corneum on the most apical surface of the tissue.
- this stratum corneum has squamous epithelial cells that have undergone apoptosis, leaving behind a keratin-rich and filled dead cell layer which doesn’t have a nucleus or organelles.
Stratified squamous non-keratinizing epithelium (SSNKE)
- is found in less wear-prone areas such as (1. 4 examples)
- cells produce (2.(less/more) (substrate))
- (3. Basal/apical) squamous cells do not lose their (4).
- Oral cavity, esophagus, anal canal, vagina
- Less keratin
- Apical
- Nuclei
Stratified squamous non-keratinizing epithelium (SSNKE) is found in less wear-prone areas, such as the oral cavity, esophagus, anal canal, and vagina.
Cells produce less keratin.
Apical squamous cells do not lose their nuclei. Nuclei are present in all layers.
Simple Cuboidal epithelial cells
- (1. #) layer(s)
- specialized for (2. 2 functions)
- found in (4 places)
- ciliated simple cuboidal epithelium is also found in (4)
- Single layer
- Secretion and/or absorption
- In kidney tubules, glandular ducts, ovaries, thyroid gland
- Respiratory airways
Simple cuboidal epithelial cells have a single layer which is specialized for secretion and/or absorption.
They are found in kidney tubules, glandular ducts, ovaries, and follicles of the thyroid gland.
Ciliated simple cuboidal epithelium is also found in some respiratory airways.
Stratified cuboidal epithelial cells
- (1. #) layer(s) of cells
- the underlying cell layers can be (2. same/different) because the most (3. apical/basal) layer names this epithelium.
- their function: (4)
- found in ducts of glands such as (5. List the three).
- Multiple layers
- Different
- Apical
- Protection for tissue
- Ducts of glands such as sweat, mammary, salivary
Stratified cuboidal epithelial cells have multiple layers of cells. The underlying cell layers can be different because the most apical layer names this epithelium. They function to protect tissues and are found in the ducts of glands such as the sweat, mammary, and salivary glands.
Simple columnar epithelium * specialized for (1. 2 functions) * (2. can/cannot) be ciliated Examples Uterus: _(3: (type) (ciliated/not ciliated)) Small intestine: _(4)_ Small intestinal simple columnar cells also have _(5)_ which is responsible for absorption of nutrients from the gut lumen. * _(6)_ shape
- Secretion and/or absorption
- Can be ciliated
- Uterine columnar epithelium: ciliated
- Absorptive cells (small intestine)
- Brush border of microvilli
- Pyramidal shape
Simple columnar epithelium are specialized for secretion and/or absorption. They can be ciliated.
Examples include
- Uterus: ciliated uterine columnar epithelium
- Small intestine: absorptive cells
- microvilli: brush border (in absorptive cells of small intestine)
Stratified columnar epithelium _(1. #)_ layer(s) of cells The surface layer is _(3)_ 2 Functions: _(4)_ Examples * Eye: _(5)_ * _(6)_ * _(7)_ * _(8)_
- Multiple
- Male urethra
- Columnar
- Secretion, protection
- Ocular conjunctiva of the eye
- Parts of the pharynx
- Parts of the anus
- Male urethra
Stratified columnar epithelium has multiple cell layers
The surface layer is columnar.
The stratified columnar epithelium is found in the …
* eye: ocular conjunctiva
* pharynx (parts)
* anus (parts)
* male urethra
Pseudostratified columnar epithelium
- has a layer of cells that (1. are/aren’t) all in contact with a basement membrane
- the cells also (2. Do/don’t) all reach the luminal surface
- look like (3. Cell type) but aren’t, since all cells rest on the (4)
- Examples (5)
Pseudostratified columnar epithelium
- Cells ALL contact basement membrane
- Cells DON’T all contact the luminal surface
- Stratified columnar epithelium
- Basal lamina
- Respiratory
Pseudostratified columnar epithelium has a layer of cells that ARE in contact with a basement membrane but DON’T all reach the luminal surface.
These cells look like stratified columnar epithelial cells but aren’t, since all pseudostratified cells rest on the basal lamina.
Pseudostratified columnar epithelium
- functions: (1) and (2) and (3)
- they also have (4)
- in cells like the respiratory epithelium, they have: (5) and (6) cells
Pseudostratified columnar epithelium
- protection
- Secretion
- Surface movement of mucus (by beating cilia action)
- protected basal (stem) cell niche
- Goblet cells
- ciliated cells
Pseudostratified columnar epithelium function as protection, have secretory functions, and are responsible for surface movement of mucus (by beating cilia action). They also have a protected basal (stem) cell niche.
In cells like the respiratory epithelium, they have
- goblet cells
- ciliated cells
Do the following cells have cilia? Goblet cells?
* ex. Trachea: (1) (Pseudostratified columnar epithelium)
- Trachea: Cilia - yes; goblet cells - yes
