Histology Flashcards
What is the epithelial lining of the lip
Stratified squamous non-keratinising epithelium. Sits on a connective tissue layer ( submucosa) containing collagen and elastic fibres.
Deeper layers often contain glands and skeletal muscle fibres that help to change the shape of the oral cavity
What type of epithelium is the skin
stratified squamous keratinised epithelium
How does the epithelium of the lips kept moist
Small blood vessels lie in the submucosa and fluid from these help keep moist
Epithelium of the tongue and
Covered by stratified squamous epithelium that remains non-keratinised on its ventral surface but is often heavily keratinised on its coral surface due to constant abrasion of this surface
Skeletal muscle of the tongue
Coarse bundles inside that run in different directions. Some insert onto the lower jaw ( extrinsic fibres) while others attach only to the fibrous connective tissue underlying the mucosa ( intrinsic fibres.)
Papillae
Dorsum of the tongue is thrown into complex folds known as papillae. Tall, pointed file form papillae are the most common and cover the whole of the anterior two thirds of the tongue, producing a rasp like surface
Locations of papillae on the tongue
Less numerous mushroom shaped fungi form papillae found at the tip and sides. Pale-staining taste buds embedded in the eilithelium on the lateral sides of these papillae.
A v-shaped row of dome-shaped circumvallate papillae separate the anterior two thirds and the posterior third on the tongues surface. These too bear taste buds.
What do the parotid glands produce
A watery enzyme rich secretion ( serous secretion) rich in alpha amylase that digests starch.
Secretory cells of the parotid gland
All the same type ( a wholly serous gland). Arranged in spherical clumps called acini that resemble bunches of grapes ( the stalks being the duct system if the gland). Cells are pyramidal in shape with a spherical nucleus. Basal cytoplasm is filled with RER and the apex of the cell contains prominent secretion granules.
Where do the acini of the of the parotid gland drain into
Into ducts lined by a cuboidal epithelium that may become stratified at its distal end.
How do the sublingual salivary glands discharge their secretions into the floor of the mouth
A series of ducts either side of the frenulum of the tongue
Sublingual salivary glands
Branched tubular-acinar glands that produce a sticky mucous rich secretion that helps to lubricate the mouth of the bolts of food. The secretory cells appear swollen and are filled with pale staining mucus granules. The oval nucleus is squashed to the base of the cell.
Where do secretions of the Sublingual salivary glands drain into
Ducts lined by a simple or stratified cuboidal epithelium whose cells appear pinker than the secretory cells
How do the submandibular salivary glands discharge
By a pair of ducts onto the frenulum of the tongue
Submandibular salivary glands
A branched tubule-acinar type which are often intersperse by fat. Produce a mixed secretion, part mucus and part an enzyme rich secretion. Display two types of secretory cell, pale staining mucus producing cells and darker staining enzyme producing (serous ) cells. The serous cells form acini or lie at the closed ends of the tubules where they form characteristic crescent-shaped “Demi-lunes” (half moons)
How do the parotid and submandibular salivary glands contribute to growth of the epithelium of the go tract
Major source of epidermal growth factor that promotes its growth.
Surface if the epiglottis
Most of its surface covered by a stratified squamous epithelium although the lower part of its posterior surface has a pseudo stratified columnar ciliated epithelium ( respiratory epithelium)
Internal contents of the epiglottis
A plate of elastic cartilage, and it’s submucosa often contains lymph nodules and salivary glands.
Layers of the GI tract
Innermost mucosa
Underlying submucosa
External muscle coat ( muscular is proprietary - sometimes referred to as the muscular is externa)
A serous ( in some regions)
Components of the mucosa of the gut tube
Three components, a lining epithelium that is often thrown into folds, a layer of connective tissue ( laminate proprietary) that often contains lymphoid tissue and a ring of smooth muscle ( muscularis mucosa).
Components of the submucosa of the GI tract
Composed of loose connective tissue that may contain glands and lymphoid tissue. Many of the blood vessels that supply the gut run in this layer. A rich plexus of nerves that is part of the enter is nervous system ( Meissner plexus) is also present in this layer.
Components of the muscularis propria of the GI tract
Normally consists of two layers of smooth muscle whose contractions help to break up the food and to propel it along the alimentary tract. Sandwiched between these layers are nerves that are also part of the enteric nervous plexus (auberbacks plexus).
What covers the outside surface of those parts of the gut tube that face the peritoneal cavity
A aerosol layer consisting of a simple squamous epithelium
Epithelial lining of the oesophagus
Stratified squamous non-keratinised epithelium. Underneath this is a thin laminate propria and a narrow muscularis mucosa of smooth muscle.
How does the lining of the oesophagus change along it
Muscle layer becomes thicker and more prominent at the distal (gastric end of the tube. Below the thoracic diaphragm the epithelium is often transformed into a simple columnar type similar to that which lines the cardia region of the stomach. This region of the oesophagus can become the site of pathological change.
Submucosa of the oesophagus
Contains many sero-mucous glands whose secretions help to lubricate the oesophagus. At the distal end , the submucosa layer contains many large, thin walled veins. These may become the site of oesophageal varicosities.
Proximal end of the oesophagus
The outermost layer of muscle ( muscularis externa) is composed mainly of skeletal muscle but at the distal end it is composed mostly of smooth muscle.
