Epithelial Tissues (Prof. Anyanwu) Flashcards
The nonliving portion of a tissue that supports cells is called …………………..
Extracellular matrix
Mention the four major types of tissues
- Epithelial: protection, secretion, absorption
- Connective: support soft body parts and bind structures together
– Muscle: for movement
– Nervous: conducts impulses used to help control and coordinate body activities
In one sentence, define epithelium.
An epithelium is a sheet of cells that covers a body surface or lines a cavity.
Outline 6 characteristics of epithelia
■ Composed of closely packed cells with little extracellular material between.
■ Adjacent epithelial cells are bound together by specialized contacts such as desmosomes and tight junctions.
■ Exhibits polarity by having an apical surface (free) and a basal surface (attached).
■ Supported by the underlying connective tissue.
■ Innervated but avascular.
■ Has a high regeneration capacity.
……………….. epithelium is common at sites of filteration, diffusion, osmosis.
Simple squamous
……………. epithelium is common at sites of filtration, diffusion, osmosis; eg air sacs of the lungs, walls of capillaries, linings of blood and lymph vessels
Simple squamous
…………………….epithelium is common at sites of filtration, diffusion, osmosis
Simple squamous
……………… is referred to as germinal epithelium?
The simple cuboidal epithelium at the surface of the ovary
…………… epithelium is found in the secretory portion of many glands
Simple cuboidal
……………… epithelium is found in thyroid, mammary, and salivary glands
Simple cuboidal
……………… epithelium is found in the kidney tubules
Simple cuboidal
Where is the nucleus of the cells of simple culumnar epithelium located?
Near the basement membrane
goblet cells secrete ………….
Mucus
Simple columnar epithelium function in ……………….and are found in ……………..
Simple columnar epithelium function in absorption of nutrients; secretion of mucus and enzymes and they are found in the digestive tract.
……………….. epithelium contains cells of varying heights giving the false impression of the presence of many layers
Pseudostratified columnar epithelium
Where can pseudostratified epithelium be found?
■ Along the linings of the respiratory tract
Pseudo stratified columnar epithelium is ciliated and includes goblet cells. True or false?
True
Pseudo-stratified columnar epithelium is responsible for the ……………….. which protects the terminal airways and alveoli
“mucociliary elevator”
Why does pseudostratified columnar epithelium give the false impression of the presence of many layers?
- contains cells of varying heights
- because nuclei are at 2 or more levels
Why is pseudo-stratified columnar epithelium not said to be stratified, despite its appearance?
Because all cells touch basement membrane
Pseudostratified columnar epithelium function in ……………….and are found in ……………..
Pseudostratified columnar epithelium function in protection, secretion, movement of mucus and are found in the linings of the respiratory tract
What is the main function of stratified epithelia?
Protection
cells on the free surface of stratified squamous epithelium are ………………….. while the underlying cells are ………………..in shape
Squamous shaped on the surface
and the underlying cells are cuboidal/columnar in shape
Stratified squamous epithelium are found in ………………….
– Skin
– Mouth
– Esophagus
– Anal Canal
– Vagina
…………….epithelium are found in locations subject to friction or attrition
Stratified squamous epithelium
…………………epithelium is rare, found mostly in the ducts of some of the larger glands.
Stratified cuboidal epithelium
What’s the distribution of stratified cuboidal epithelium
– Sweat glands
– Developing ovarian follicles
– Lining of larger ducts of mammary glands
– Sweat glands
– Salivary glands
– Pancreas
……………….epithelium is found in the pharynx, male urethra
Stratified columnar
………………… epithelium forms the lining of the hollow organs of the urinary system that stretch as they fill
Transitional epithelium
Transitional epithelium is found in …………………
renal pelvis, ureter, bladder, upper urethra
…………. epithelium are stratified with dome shaped surface cells
Transitional epithelium
What is the state of the of the transitional epithelium in the bladder:
a. When the bladder is full
b. When the bladder is empty
When the bladder is empty, the epithelium is at least 5-6 cells thick with rounded superficial cells that bulge into the lumen.
When the bladder is full of urine the epithelium is stretched, the epithelium is only 3-4 cells thick and the superficial cells become more squamous in appearance
State two features of transitional epithelium
■ they can stretch
■ distensibility, protection
The basal surface of epithelial cells rests upon a …………….. which anchors the epithelium to the underlying connective tissue ………………..
basal lamina, lamina propia
What is the basal lamina
The basal lamina is an organized sheet of organic molecules including collagen, most of which are synthesized by the epithelial cells.
basement membrane for a thicker structure composed of …………………
the basal lamina and reticular lamina
The reticular lamina refers to?
A layer of anchoring reticular fibers attaching the basal lamina to the underlying connective tissue.
Name the apical surface modifications
Microvilli
Cilia
Sterocillia
What are microvilli?
fingerlike projections of plasma membrane extending from the apical surface of epithelial cells into a lumen to increase surface area for absorption.
Under light microscopy, the microvilli form a striated apical border referred to as a ……………..
“brush border”
Name two common locations of the microvilli
simple cuboidal cells of some renal tubules and
simple columnar cells of small intestine
What are cilia?
Cylindrical structures on the apical surface of some epithelial cells that exhibit coordinated wavelike motion to propel a current of fluid or mucus in one direction over the epithelial surface.
What are the common locations of cilia?
Respiratory epithelium, eg the surface of the pseudostratified columnar epithelium of the trachea
Fallopian tube
What are goblet cells?
epithelial cells that produce and secrete large amounts of mucus
■ Commonly
What’s a common location for goblet cells?
the simple columnar epithelium that lines the intestines
the pseudostratified epithelium that lines the respiratory tract
Epithelial membrane = ?
Epithelium + underlying CT
Mention the major types of epithelial membrane
1) Serous membranes
2) Mucous membranes .
3) Cutaneous membrane
Where can serous membranes be found?
They line body cavities that do not open to the outside and also cover the organs within these cavities.
The epithelium of serous membrane is called a …………..
“mesothelium”.
……………….. epithelial membrane covers the surface of the body.
Cutaneous
……………… epithelial membrane line the cavities and organs that open to the outside of the body.
Mucous
……………. within the mucous membranes secrete the mucus
Goblet cells
Epithelial cells that are specialised to produce and secrete substances into ducts or into body fluids are referred to as?
Glandular epithelium
……………. are ductless glands
Endocrine glands
………………. are sometimes classified as mucous secreting unicellular exocrine glands instead of being considered as intrinsic component of epithelial membranes
Goblet cells
What are the components of exocrine glands?
Secrtory units
Ducts
Connective tissue that support the aforementioned components.
What is a secretory unit?
A secretory unit is a group of secretory epithelial cells that release their secretion into a lumen, whereas a duct is an epitheIial lined tube that conveys the secretions from a secretory unit to an epithelial lined surface
Outline the four ways through which exocrine glands can be classified.
Classification based on structure
-simple gland
-compound glan
Based on the secretory product of the exocrine gland
-Serous
-Mucous
-Seromucous/mixed
According to overall shape of their secretory unit
-tubular gland
-alveolar glands
-tubuloalveolar glands
Classification based on mechanism of secretion
-merocrine: fluid is released by exocytosis
-apocrine: small portion of cell is pinched off
-holocrine: cells fill with product and rupture
Examples of merocrine gland include
salivary and pancreatic glands
Classify mammary, and sebaceous glands on the basis of secretion mechanism
The mammary gland is an Apocrine gland
The sebaceous gland is a holocrine gland
Classify sweat and pancreatic glands on the basis of their structure.
The sweat gland is a simple gland
The pancreatic gland is a compound gland
Instead of releasing their secretion into ducts, endocrine glands discharge their secretions into ………..
The bloodstream
Secretory cells of endocrine glands are grouped around ………………
wide fenestrated capillaries
Why are the secretions of endocrine glands known as hormones?
because they elicit functional changes in target cells that they reach by way of the bloodstream
