L9: Microscopic anatomy of glands Flashcards
During fetal development, all glands originate from?
The epithelium
Explain how glands are formed (glands in general ya3ni mo specifically endo wala exocrine)
During fetal development epithelial cells proliferate and
penetrate the underlying connective tissue and differentiate
into glandular epithelial tissue by down growth
How are exo and endocrine glands formed?
Exocrine: If secretion from the glandular tissue reach to the surface of the lining or covering epithelium by a duct lined with epithelium, then gland is called exocrine gland
Endocrine: The glandular tissue if loses its connection with lining epithelium from which it developed, and then it develops into endocrine gland
The cells of the endocrine glands secrete?
Hormones
The cells of endocrine glands are arranged in the form of? And how are the secretory products released?
Form: arranged In the form of cords or in the form of follicles with lumens for storing the secretory product.
Product release: From either the cords or follicles of endocrine cells, the secretory product is released outside the cells and taken up by the blood vessels for distribution throughout the body
True or false
Endocrine glands have ducts
False
Describe the cellular arrangement of exocrine and endocrine glands
Exocrine glands:
Arranged to form tubular, acinar, Arranged tubuloacinar glands
Endocrine glands:
Arranged into clusters of cells, arrangement cords of cells, follicle or remain as dispersed cells
True or false
Exocrine glands release their secretions into the CT
False, Released on to the surface body/lumen of viscera through the ducts
Exocrine and endocrine gland are covered by a __________ capsule
connective tissue
From the deep surface of the capsule, _________ arise and divide the gland into _________ and _________, thus connective tissue supports the glandular tissue.
From the deep surface of the capsule, septa arise and divide the gland into lobes and lobules, thus connective tissue supports the glandular tissue.
How is the glandular tissue supported?
By septa and capsule
Inside the gland the duct runs through connecting septa and branches repeatedly, until its smallest branches end in the?
secretory portions of the gland
What is the smallest branch in a gland called?
Parenchyma
What runs through the septa?
Duct and Blood vessels
Exocrine glands are divided into?
Unicellular and multicellular glands
What is an example of unicellular gland?
Goblet cell
What are multicellular glands divided into?
Whats an example of simple tubular?
Large intestine, intestinal glands of the colon
Whats an example of simple alveolar/acinar?
Urethra- paraurethral glands
Whats an example of simple tubuloalveolar/tubuloacinar?
Mammary gland
Whats an example of compound tubular?
Duodenum- Brunner’s glands
Whats an example of Compound alveolar/Acinar?
Pancreas
Whats an example of Compound tubuloalveolar tubuloacinar?
(Submandibular) Salivary glands
Whats the difference between compound acinar and simple branched acinar?
simple branched acinar: has only ONE duct (yellow)
compound acinar: has multiple ducts.
Functional classification of exocrine glands (Based on mechanism of secretion) are divided into?
Simple glands have unbranched ducts, although the ducts may be short or long and coiled, the secretory portions attached to these ducts may themselves be branched, the secretory part may have different shapes:
- Tubular-cylindrical/tube shaped
- Acinar-bulbous or sac like.
- Tubuloacinar-Sac like secretory part
Where would you find simple coiled tubular?
Eccrine sweat glands
Where would you find simple branched tubular?
Stomach-pyloric glands
Where would you find simple branched acinar?
- Sebaceous glands
- Mucous glands of cardiac part of the stomach
What do goblet cells secrete? And how?
Highly viscous mucin material secreted by exocytosis and is then hydrated to form mucus in the lumen.
Where would you find goblet cells?
**In simple columnar epithelium: **
Small intestine & Large intestine
In Pseudostratified columnar epithelium:
Respiratory epithelium
Ultra structurally a goblet cell shows?
- a basal nucleus surrounded by RER (R),
- a large Golgi complex (G) just above the nucleus, and an apical end filed with large secretory granules (SG)
containing mucins.
Where would you find merocrine glands?
- pancreas (pancreatic acinar cells)
- salivary glands
Where would you find apocrine glands?
- Mammary glands
- ciliary gland of the eyelid
Where would you find holocrine glands?
- Sebaceous glands of hair follicles
- Tarsal (Meibomian) glands of the eyelids
Holocrine secretion method:
In Apocrine gland, secretion involves loss of a large membrane-enclosed portion of apical cytoplasm, usually containing one or more _____________
lipid droplets
In apocrine secretion, (Eg. mammary gland) the secreting portions of cells are characterized by the discharge of the secretory product with a pinched off portion of the apical cytoplasm (arrows).
The released portion of cell contains ___________
lipid droplet(s).
• Most exocrine glands are ___________ in nature
merocrine
Classification of exocrine glands (Based on type of secretion):
What are the characteristics of serous cells?
- Serous acinar cells are roughly pyramid-shaped, with its
apex at the lumen. - Nucleus is rounded or oval in shape
- The apical ends are eosinophilic due to the abundant immature and mature secretory granules present there.
True or false?
Serous acinar cells are roughly oval shaped
False, pyramid shaped
True or false?
The lumen of serous acinar cells is small.
True
Where would you find serous acinar cells?
In Parotid salivary gland & Pancreas
Ultrastructurally, serous
cells show ?
- Abundant RER,
Golgi complexes, and
secretory granules.
Which cell is larger…
Serous or mucous cells?
Mucous cells
What are the characteristics of Mucous cells?
- Have flattened basal nuclei
- The apical region and most of the other cytoplasm of mucous cell are filled with secretory granules containing mucin.
- The basal region contains the RER, nucleus,
and a well-developed Golgi apparatus.
True or false?
Mucous cells have flattened cells near the apical region
False, they DO have flattened nuclei, but it’s near the basement membrane.
The RER and Golgi are very rich in enzymes
called?
And what is their function?
The enzymes are called glycosyltransferases, which attach sugars to polypeptide chains to make glycoproteins.
Mucus contains many _______ with important _________-binding properties.
Mucus contains many glycoproteins with important water-binding properties.
True or false?
The lumens of mucous tubules are larger than those of serous acini
True
Examples of where mucous cells are found?
- Sublingual salivary glands
- Gland in the respiratory tract
- the genital tract.
(Ya3ni it’s common sense,these are the places ely mucus is most needed)
What are serous demilunes?
Clumps of serous cells at the ends of some mucous tubules appear as crescent—shaped structures
The submandibular salivary glands have both? And what are they shaped as?
Mucous and serous secretory units, typically shaped as acini and tubules respectively.
Seromucous, compound tubuloacinar gland is found in?
Submandibular salivary glands
What are myoepithilial cells?
Myoepithelial cells are muscle like cells (they have actin and myosin filaments) located between the bases of epithelial cell and the basal lamina.
Which cell is star shaped?
Myoepithilial cells
What are the characteristics of myoepithilial cells?
- Myoepithelial cells are located between the bases of epithelial cell and the basement membrane.
- Star shaped
- Long processes embrace the acinar cells with secretory granules.
Functions of myoepithilial cells: (2)
- Specialized for contraction-they have actin and myosin the base of the secretory call and basement membrane
- Contraction of the myoepithelial cell compresses the acinus which aids in the expulsion of secretory products into the duct.
Features of protein-secreting cell: (3)
1) The protein secreting cells are intimately associated with the capillary at their base and lumen at their apex.
2) Numerous secretory granules are located at the apical part of the cells.
3) Cells are rich in rough endoplasmic reticulum , Golgi apparatus and prominent nucleus.
Example of protein secreting cell?
Exocrine pancreatic acinar cell
Since the protein secreting cell is rich in _________, the steroid secreting cell would be rich in ________, where steroid _______ takes place)
Since the protein secreting cell is rich in RER, the steroid secreting cell would be rich in SER, where steroid synthesis takes cell)
The steroid secreting cell is intimately associated with the?
the capillary (Cap) endothelium via microvillar channels (connects plasma membrane of cell to the capillary)
Steroid secreting cell is mostly found in?
Endocrine glands
Describe the ultrastructure of this photo
Ion transporting cells have _______________ on their cell
membrane.
ion transporters
What are ion transporters? And where are they found?
Ion transporters are integral membrane proteins that
control cellular uptake and efflux of inorganic ions and they are found on the cellular membrane of ion transporting cells.
Describe Ion-transport across the cell membrane
- Sodium and water diffuse readily from the lumen
into the interior of the cell. - Then, at the basal and lateral membranes of the cells,
sodium ions are actively transported into the extracellular
fluid of the surrounding connective tissue and blood vessels. - This creates a high sodium ion concentration gradient
across these membranes, which in turn causes osmosis
of water as well.
These are the mechanisms by which almost all the…. (Talking about ion transport across the cell membrane)
nutrients, ions, and other substances are absorbed into the blood from the intestine;
they are also the way the same substances are
reabsorbed from the glomerular filtrate by the renal tubules.
Ion and water transport across epithelia can occur in?
in different directions, depending on which tissue is involved
Describe Ion and water absorption and secretion:
Absorption: The direction of transport is from the lumen to the blood vessel
Secretion: The direction of transport is from the blood vessel to the lumen
Together, septum and capsule are called?
Stroma
Why are the apical ends of serous cells eosiniphillic?
Due to the abundant immature and mature secretory granules there
What is the function of microvillar channels?
Connects the plasma membrane of the cell to the capillary
