histo 1 imp points Flashcards
GLANDS
alimentary canal and associated organs
bolus
digestive juices: saliva, gastric juices, pancreatic juices, intestinal juice and bile.
saliva= 0.5 - 1.5 L per day
total amount of digestive juice = 7 L
mucin= mucous+ water
mucosa is another name for the mucous membrane.
mucosa= epithelium+ lamina propria muscularis mucosa( thin layer of smooth muscle)
PH in alimentary canals
saliva: 6.8-7
stomach: 1.5-3
intestine: 7.8-8
bile: 7.8- 8
pancreatic secretion:8-8.4
oral cavity division
1- vestibule: spaces btw teeth, cheeks, lips( soft part of the mouth tissue located antly or buccally to the teeth).
2- oral cavity proper
salivary glands division
1- major salivary glands
2- minor salivary glands
MAJOR SALIVARY GLANDS
secretory acini are organized into lobules, the major salivary glands are covered by a capsule of dense CT from which septa divide the secretory portions of the gland into lobes and lobules. the septa contains larger blood vessels and excretory ducts.
acini types: serous, mucous, mixed
basic secretory unit of salivary glands= salivon consists of acinus, intercalated duct and excretory duct.
acinus sac composed of secretory cells. acini of salivary glands contain serous cells and mucous cells or both.
mixed acini: both serous and mucous cells. during preparation mucous acini have a cap of serous cells.
Serous cap or Giannuzzi Demilune: it is halved moon and composes of serous cells with basophilic cytoplasm. These serous cells are protruding from mucous cells; this is an artifact due to the different shrinkage of the two types of the cells.( serous cells are shifted away from the mucous secreting cells): artifact of the routine fixation method.
serous cells have pyramidal shape. they store their secretions in zymogen granules
mucous cells : mucinogen granules.
myoepithelial cells: contractile cells with numerous processes. located btw the basal lamina and plasma membrane of the epithelial cells. the contractile filaments stained by eosin.
1- parotid glands:
largest MG
located ant to the ear, extending from cheek bone up to the mandible( located subcutaneously)
excretory ducts= parotid ducts= stensen’s duct
the duct is opened in to the parotid papilla( oral vestibule) = opposite upper 2nd molar
innervation:
- sympathetic innervation: is provided by the cervical ganglion and distributes by arterial system.
- parasympathetic innervation: CN 9
serous secretory only
we can see large fibers of facial nerve in the cross section ( interlobular septa)
large amount of adipose tissue can be found in the intralobular part of the stroma
FACIAL NERVE ONLY PASS THROUGH THE parotid gland and does not give off any innervation.
2- submandibular glands:
located at the: floor of the mouth postly occupying the digastric triangle( submandibular triangle)
mixed glands : both mucous and serous acini( serous> mucous)
submandibular ducts= wharton’s duct= opens in sublingual caruncle on each side of the lingual frenulum
innervation:
- sympathetic innervation: is provided by the cervical ganglion and distributes by arterial system.
parasympathetic: by CN7
both submandibular and parotid glands have long ducts that extend from secretory portion of the gland to the oral cavity.
intercalated ducts are less extensive than parotid gland.
3- sublingual glands: located at the floor of the mouth antly
mixed glands: mucous> serous( dominantly mucous)
short ducts= some of them empties into the submandibular duct, some empties into the sublingual folds.
innervation:
- symp: is provided by the cervical ganglion and distributes by arterial system.
parasym: CN7
mostly lack of intercalated and striated ducts.
function of saliva:
- moistening the oral cavity and helps in mastication, speech, etc.
- lysozyme enzyme: IgA and other antibacterial substances protects against caries and oral cav infections. IgA is produced by plasma cells in the stroma connective tissue.
xerostomia: dry mouth( when you don’t make enough saliva)
submandibular glands secretes the majority of the saliva. parotid is the second one.
rule: mitochondria makes the cytoplasm eosinophilic.
saliva= water, prots, electrolytes.
Ducts of the gland
We can see so many small and large ducts around the serous and mucous acini:
Intercalated ducts: these are smallest ducts and these appears like a serous secretory unit, although their lumens are visible. These are joining the secretory unit. Their lumens are lined by simple cuboidal epithelium and their cytoplasm is basophilic. intralobular ducts
Intercalated ducts are directly connected with either the mucous or serous secretory unit
Striated duct(salivary duct): intercalated ducts are united together and make some larger ducts called striated duct(salivary duct). These ducts are bigger in diameter and also the lumens are bigger. The lining epithelium of these ducts is simple cuboidal or simple columnar epithelium and cytoplasm is eosinophilic( large amount of mitochondria; the large amount of mitochondria is needed due to the active transports and ions are transported by these active transport mechanism and can modify the ‘‘ionic composition of the saliva’’. intralobular ducts
Excretory Duct: several striated ducts are united and make these ducts. These are even bigger ducts and the epithelium of these ducts are pseudostratified columnar or stratified cuboidal or stratified columnar epithelium. This duct is embedded(within) in the connective tissue septum. empty in oral cav. interlobular and interlobar connective tissue
Connective tissue septa divide the secretory units to lobules.
Excretory ducts are interlobular ducts.
striated ducts and intercalated ducts are intralobular ducts.
MINOR SALIVARY GLANDS:
LOC
NAME
they don’t have capsule around them.
located in submucosa
named based on their location: LABIAL, PALATAL, BUCCAL, LINGUAL
secreted directly to the oral cav by short ducts.
Sebaceous glands:these are Holocrine type of exocrine glands. These glands do not have ducts and they use little canals in the hair shaft to release their secretum; that’s why these glands are always in the vicinity of the hair follicle because they need have contact by these canals to secrete their secretum to the surface of the skin. Their secretion is called sebum( contain highly lipid) Secretory unit of the glands is called acinus and these cells are modified cells of the epithelium. Their cytoplasms are almost unstained( pale) and has a foamy nature(little bubbles present); it is due to the loss of lipid using xylene during embedding stage of sample preparation.( is a chemical artifact). The nucleus is pale in color(bright), contain loosely packed chromatin( Euchromatic nuclei). The young cells can be find on the basal part of the secretory unit. During the lifespan, young cells shifts toward the more apical portion of the gland(from red to green); therefore in the more apical portion of the gland we have much older cells and young cells dye on the apical surface of the gland. Young cells dye by apoptosis.
Sweat glands:(eccrine glands):
Mechanism of these glands is Merocrine. And these glands are tubular glands because it is a exocrine gland with duct and ducts conducts the secretum to the surface.
The whole length of the ducts are not visible because they are not always parallel to the plane of sectioning.
The duct of the sweat gland lines by stratified cuboidal epithelium( a kind of lining epithelium which lines the ducts of the sweat glands)
There are 2 major types of secretory cells in the secretory portion of eccrine sweat gland:
1-clear cells(pale cells): have a pale cytoplasm: they produce watery component(wolf says waterous)( electrolyte component) and glycogen rich component of the secretum. The glycogen and small ions were lost during formalin fixation.(artifact)
2-dark cells: they have basophilic cytoplasm due to the presence of RNA and they produce and release the protein rich component.
The number of clear cells are more than dark cells in the eccrine glands.
The products of both mix in the lumen.
Each secretory unit is surrounded by basement membrane.
The epithelium here is not a lining epithelium; it’s glandular epithelium. And I t is a simple one.
Myoepithelial cell: We can see another cell nucleus at the periphery of the secretory unit of the sweat gland; which is called Myoepithelial cell. These cells are above the basement membrane(????? In the sample I could not find really between them). Their nuclei are squamous and contain no nucleolus, densely packed chromatin( heterochromatin) and very darkly stained. Myoepithelial cell is a transitory cell type. It is a modified epithelial cell because it contains unusually high amount of contractile myofilaments which are characteristic for muscle cells; therefore Myoepithelial cells are resemble as muscle cells. These cells have processes that are not visible under light microscope(electron mic); their processes surround the secretory cells. When this Myoepithelial cells contract, then the processes are squeezing the myoepithelial cells and they release substances that provide secretory of acinus.
If we see a Euchromatic nucleus we can say that the cell is more active than the cell in the heterochromatin nucleus.( e.g. transcription is in higher rate ) because the chromatin has lesser folded and can be transcribed more than dense one.
Smell glands(modified sweat glands): these are called due to their secretory products, which release to the surface of the skin, is a nutrient for bacteria(there are some bacteria on the surface of our skin) and the metabolic end product of bacteria has a kind of bad smell.
It is very important to know that the secretory of the glands do not smell badly( only the end product of bacteria smells bad).
These glands are similar to glands around genital or anus glands.
The mechanism of secretory in these glands is Apocrine; it is because of the morphological secretion of these glands.
APOPTOSIS
Apoptosis= a programmed cell death
Apoptosis is divided into 3 important events or stages:
1-Karyopyknosis: nuclei become smaller darker(more basophilic) and denser
2-Karyorrhexis: nuclear fragmentation in pyknotic( in our sample we cannot see anywhere)
3-Karyolysis: disappearing of the nuclei fragments.
Later in upper portion of the youngest cells the nucleus gets darker and smaller(shrinkage); this is called Karyopyknosis. This is the first morphological sign of apoptosis.
ORAL CAVITY
is covered by oral mucosa: masticatory mucosa+ lining mucosa+ specialized mucosa
masticatory mucosa: Found on gingiva and hard palate, Keratinized and some areas parakeratinized, Stratified squamous epithelium( similar to thin skin they don’t have stratum lucidum)
PARAKERATINIZED: similar to keratinized but the superficial cells do not lose their nuclei and cytoplasm does not stain intensely with eosin. The nuclei of the parakeratinized cells are pyknotic (highly condensed) and remain until exfoliated.
The lamina propria is loose and highly papillated.
Deep to the lamina propria is a reticular layer of denser connective tissue.
The depth and number of connective tissue papillae contribute to the immobility of masticatory mucosa thus protecting it from frictional and shearing stress.
lining mucosa: Found on the lips, cheeks, alveolar mucosal surface, floor of the mouth, inf surfaces of the tongue and soft palate. Non keratinized but in some places para
specialized mucosa:
layers of the lamina propria: in general consists of 2 components:
- the papillary layer
- the reticular layer
TONGUE1
tongue is attached to the mandible and hyoid bone. the dorsal surface of the tongue is divided into by a V-shaped depression, sulcus terminalis:
post ⅓ of the tongue= pharyngeal surface= lingual tonsil( consists of accumulation of lymphatic tissues)= base of the tongue
ant ⅔ of the tongue= oral surfaces = body of the tongue
root of the tongue is connected to the mandible and hyoid bone
the apex of the v points is located postly called foramen cecum. marks the site in the embryo where the epithelium invaginated to form the thyroid gland.
these surfaces are separated by v shaped terminal sulcus of the tongue.
muscles of tongue are called lingual muscles: they are extrinsic( have one attachment outside the tongue) and intrinsic( without external attachment) muscles: these muscles are skeletal muscles. the striated muscles are arranged in bundles that run in 3 planes in which each arranged at right angles to other two: causes flexibility and precision in movements. variable amounts of adipose tissue are found among the muscle fiber groups.
lingual papillae: are mucosal irregularities and elevations cover the dorsal surface of the tongue ant to the sulcus terminalis.
The lingual papillae and their associated taste buds constitute the specialized mucosa of the oral cavity.
4 types of papillae are described:
- *• Filiform papillae: are the smallest and most numerous in humans. They are conical, elongated projections on connective tissue that are covered with highly keratinized stratified squamous epithelium. This epithelium does not contain taste buds. The papillae serve only a mechanical role. Filiform papillae are distributed over the entire anterior dorsal surface of the tongue, with their tips pointing backward. They appear to form rows that diverge to the left and right from the midline and that parallel the arms of the sulcus terminalis.**
- *• Fungiform papillae, mushroom shaped projections located on the dorsal surface of the tongue. They tend to be more numerous near the tip of the tongue. Taste buds are present in the stratified squamous epithelium on the dorsal surface of these papillae.**
- *• Circumvallate( vallate) papillae are the large, dome-shaped structures that reside in the mucosa just anterior to the sulcus terminalis The human tongue has 8 to 12 of these papillae.**
- *• Foliate papillae consist of parallel low ridges separated by deep mucosal clefts. which are aligned at right angles to the long axis of the tongue. They occur on the lateral edge of the tongue. In aged people**
- *cannot be found but in young people can be. they have taste buds.**
- *In histologic sections, taste buds appear as oval, pale staining bodies that extend through the thickness of the**
- *epithelium. A small opening onto the epithelial surface at the apex of the taste bud is called the taste pore.**
3 principle cell types are found in the taste buds:
- Neuroepithelial (sensory) cells are the most numerous cells in the taste bud. These elongated cells extend from the basal lamina of the epithelium to the taste pore. through which the tapered apical surface of each cell extends microvilli. Near their apical surface, they are connected to neighboring neuroepithelial or supporting cells by tight junctions. At their base, they form a synapse with the processes of afferent sensory neurons of the facial (cranial nerve VII), glossopharyngeal (cranial nerve IX), or vagus (cranial nerve X) nerves. The turnover time of neuroepithelial cells is about 10 days. This cell contain taste receptors on their surface.
- Supporting cells are less numerous. They are also elongated cells that extend from the basal lamina to the taste pore. Like neuroepithelial cells, they contain microvilli on their apical surface and possess tight junctions, but they do not synapse with the nerve cells. The turnover time of supporting cells is also about 10 days.
- Basal cells are small cells located in the basal portion of the taste bud, near the basal lamina. They are the stem cells for the two other cell types.
In addition to those associated with the papillae, taste buds are also present on the glossopalatine arch, the soft palate, the posterior surface of the epiglottis, and the posterior wall of the pharynx down to the level of the cricoid cartilage. These cells react to five basic stimuli: sweet, salty, bitter, sour, and umami.
In general, taste buds at the tip of the tongue detect sweet stimuli, those immediately posterolateral to the tip detect salty stimuli, and those more posterolateral detect sour- tasting stimuli. Taste buds on the circumvallate papillae detect bitter and umami stimuli.
- The complex nerve supply of the tongue is provided by cranial nerves and the autonomic nervous system: General sensation (refers to such things as pain, thermal sensation, touch and pressure) for the anterior two-thirds of the tongue (anterior to the sulcus terminalis) is carried in the lingual nerve( mandibular division of the trigeminal nerve (CN5). General sensation for the posterior one third of the tongue
is carried in the glossopharyngeal nerve (cranial nerve IX) and the vagus nerve (cranial nerve X). - Taste sensation is carried by the chorda tympani, a branch of the facial nerve (cranial nerve VII) anterior to the sulcus terminalis, and by the glossopharyngeal nerve (cranial nerve IX) and vagus nerve (cranial nerve X) posterior to the sulcus.
- Motor innervation for the musculature of the tongue is supplied by the hypoglossal nerve (cranial nerve XII).
- Vascular and glandular innervation is provided by the sympathetic and parasympathetic nerves. They
supply blood vessels and small salivary glands of the tongue. Ganglion cells are often seen within the
tongue. These cells belong to postsynaptic parasympathetic neurons and are destined for the minor
salivary glands within the tongue. The cell bodies of sympathetic postsynaptic neurons are located in the
superior cervical ganglion.
the inf surface of tongue)
lacks papillae but have a number of linear mucosal folds:
single median fold= frenulum of the tongue= it is continuous with the mucosa covering the floor of the oral cav.
on each side of the frenulum is a lingual vein, and lateral to each vein is a rough fimbriated fold.
pharyngeal surface: the mucosa covering the surface of this part is irregular in contour because of the many small nodules of lymphoid tissue in the submucosa. these nodules are collectively the lingual tonsil.
the tongue is composed of muscle, it is completely divided into left and right halves by a median sagittal septum composed of connective tissue. it means all muscles of the tongue are paired. there are intrinsic and extrinsic lingual muscles :
all muscles of the tongue are innervated by the hypoglossal nerve, except: palatoglossus innervated by vagus nerve.
tongue2( muscles of the tongue are visceral striated muscle)
intrinsic muscles: the muscles originate and insert into the substance of the tongue, they change of the tongue, all are innervated by hypoglossal nerve. they are working in pairs or one side at a time the intrinsic muscles of the tongue contribute to precision movements of the tongue required for speech, eating, and swallowing
superior longitudinal muscles
inferior longitudinal muscles
transverse muscles
vertical muscles
extrinsic muscles: originate from the structure outside of the tongue and inserts into the tongue, there are 4 extrinsic muscles on each side)
genioglossus muscles: fan shaped muscles
- depress the central part of the tongue
- protrude the ant part of the tongue out of the oral fissure( stick your tongue out). this can be used as a test for hypoglossal nerve. zabano bayad be surate barabar kharej beshe agar be ye samt bashe nerve moshkel dare. agar nerve ye samtesh kar nakone zabun hamun tarafi mire.
hyoglossus muscles: quadrangular muscles. lateral to the genioglossus, it is lateral to the attachment of the middle constrictor muscle of the pharynx. hyoglossus muscle is an imp landmark:
- the lingual artery from the external carotid artery in the neck enters the tongue deep to the hyoglossus btw the hyoglossus and genioglossus.
- the hypoglossal nerve(cn12) and lingual nerve ( branch of the mandibular nerve) from the neck and infratemporal fossa, respectively, enter the tongue on the external surface of the hyoglossus.
styloglossus muscles
palatoglosus muscles
these muscles moving and positioning the tongue( protrude, elevation, depress, retract)
sup mental spine: on mandibular symphysis.
the geniohyoid muscles originate from inf mental spine
