Histo 17A- epithelium of digestive

how can you differentiate between tunica adventitia or serosa

adventitia Thick layer of connective tissue lacking mesothelium. Has no "finished edge" serosa Thin layer of loose connective tissue with a simple squamous covering epithelium

gastric mucosa

alkaline mucus layer for protection

at what point in the GI does the keratinization stop!!

at the esophagus- there is no more keratinization starting there

4 types of taste buds

filliform fungiform vallate foliate

4 main layers

four main layers: the mucosa, submucosa, muscularis, and serosa

rugae

large, longitudinally directed folds called rugae, which flatten when the stomach fills with food.

gastric and duodenal ulcers- causes

painful erosive lesions of the mucosa may extend to deeper layers occur anywhere between the lower esophagus and the jejunum causes Helicobacter pylori nonsteroidal anti-inflamma- tory drugs overproduction of HCl or pepsin lowered production or secretion of mucus or bicarbonate.

what organs of digestion are in the oral cavity

salivary glands - parotid gland -sublingual gland -submandibular gland salivary duct tongue teeth

outer layer stomach

serosa

answer

skeletal muscle

answer

taste bud

answer

(A) Esophagogastric junction this is the transition zone between the epithelia

Q1- A 19-year-old woman presents with painful cold sores on her lower lip. Physical examination reveals several vesicles and ulcers in the lesion area. Infection with which of the following pathogens is the common cause of cold sores? (A) Borrelia vincentii (B) Epstein-Barr virus (C) Herpes simplex virus type 1 (D) Human herpes virus 8 (E) Streptococcus pyogenes

(C) Herpes simplex virus type 1

Q5- Rugae are found in which of the following segments of the GI tract? (A) Esophagus (B) Large intestine (C) Rectum/anal canal (D) Small intestine (E) Stomach

(E) stomach

what makes up the mucosa of digestive system (3)

(a) Epithelium (Absorption) - Simple cuboidal or a simple columnar - Function: Secretory (Stomach); Secretory and absorptive (Small and large intestines) (b) Lamina propria (Support) - Loose connective tissue - Blood and lymphatic vessels (c) Muscularis mucosae (Motility) variable thickness and depends on the function of the organ- also func in motility- not always continuous

functions of the tongue

- Chewing, Swallowing; - Speech, voice modulation; - Kissing. - taste Flavors 1- Salty 2- Sweet 3- Bitter 4- Sour 5- Monosodium Glutamate(Umami)- Ikeda et al., 1908; Nelson et al., 2002 6- Water (?) 7- Calcium (?) Todoff, et al. 2007 8- Fat (?)- Abumrad, et al. 2011

what makes up the submucosa if digestive system

- Loose connective tissue - Large blood vessels, large lymphatic vessels; Submucosal nerve plexus (Meisnner's)

esophagus features and function

- Muscular tube - Approximately 25cm (10 inches) - Conduit for food Upper and lower esophageous sphincters Non keratinized strat squam the esophageal glands, which lubricate and protect the mucosa. Near the stomach the mucosa also contains groups of glands, the esophageal cardiac glands, which secrete additional mucus

esophageal Muscularis externa, three distinct parts:

- Upper third skeletal muscle, - Mid third skeletal and smooth muscle, - Lower third smooth muscle

esophagogastric junction characteristic

Abrupt change from stratified squamous epithelium to simple columnar epithelium (invaginates as gastric pits GP) The mucosa contains mucus-secreting esophageal cardiac glands (ECG) and mucous cardiac glands (CG) opening into the superficial gastric pits. Strands of muscularis mucosae (arrow) separate the mucosa and submucosa (SM)

outer and inner composition of taste buds

All have keratin Filliform usually has more All have core of CT

how do the pits and glands change as you go down the stomach

As we progress down the stomach, pits get deeper and glands get shallower, but more branched

cells of the taste bud

BAGS *gustatory pore support cell gustatory cell basal cell afferent nervous fiber

esophageal metaplasia

Barrett's esophagus GERD (Gastroesohageal Reflux disease)

parietal cells defining characteristics

Be familiar with why it looks like this Soo many mitos- for ion pumps To create and release the HCL The membrane invaginates to secrete it Looks like microvilli but its not Round or pyramidal 1-2 nuclei- central Eosinophilic cytoplasm- mitochondria deep, circular invagi- nation of the apical plasma membrane to form an intracellular canaliculus with a large surface area produced by thousands of microvilli carbonic anhydrase catalyzes the conversion of cytoplasmic water and CO2 into HCO3+ and H+. The HCO3+ is transported from the basal side of the cell and H+ is pumped from the cell apically, along with Cl− . In the lumen HCL is made - Parietal cell secretory activity is stimulated both by parasympathetic innervation and by paracrine release of histamine and the polypeptide gastrin from enteroen- docrine cells.

features of of body/fundus

Body & Fundus - Pepsinogen/HCl (digestion) - Rugae: shallow pits; deep glands

special function of cardia

Cardia - Mucous production (protection)

4 regions of stomach

Cardia Fundus Body Pylorus More mucus cells in pyloris and cardia to neutralize acid

the lips- what makes up these zones core external portion vermillion zone internal portion

Core Skeletal muscle fibers External portion Thin skin organization (epidermis and dermis). Hair follicles; Sebaceous and sweat glands. Vermillion zone Thin skin organization with thin epidermis. Capillary loops near surface=pink color. Lacks glands but rich sensory and capillaries. Internal portion Lined by stratified squamous epithelium (Oral mucosa)

enamel

Derived from ectoderm. Tall columnar cells (ameloblasts) that secrete the organic matrix (Tomes processes). Growth of the hydroxyapatite crystals to produce each elongating enamel rod is guided by a small (20 kDa) protein amelogenin, the main structural protein of developing enamel. Hardest component of human body interlocking columns called enamel rods (or prisms) ectoderm

origin of the tongue

Derived from the Branchial arches and Occipital myotomes

describe the layers of a tooth

Each tooth has a crown exposed above the gingiva, a constricted neck at the gum, and one or more roots that fit firmly into bony sockets in the jaws called dental alveoli The crown is covered by very hard, acellular enamel and the roots by a bone-like tissue called cementum. These two coverings meet at the neck of the tooth. The bulk of a tooth is composed of another calcified material, dentin, which surrounds an internal pulp cavity The pulp cavity narrows in each root as the root canal, which extends to an opening (apical fora- men) at the tip of each root for the blood vessels, lymphatics, and nerves of the pulp cavity. The periodontal ligaments are fibrous connective tissue bundles of collagen fibers inserted into both the cementum and the alveolar bone.

effects of enteroendocrine cell signaling

Effects of the hormones include regulation of peristalsis and tract motility; secretion of digestive enzymes, water, and elec- trolytes; and the sense of being satiated after eating.

enteroendocrine cells defining characteristics

Enteroendocrine cells are scattered epithelial cells in the gastric mucosa with endocrine or paracrine func- tions. In the fundus small enteroendocrine cells secreting serotonin (5-hydroxytryptamine) are found at the basal lamina of the gastric glands (Figure 15-20). In the pylorus other enteroendocrine cells are located in contact with the glandular lumens, including G cells producing the peptide gastrin. Seen on TEM w/ chromium and silver salts other names enterochromaffin (EC) cells and argentaffin cells, Named now for that they produce- APUD= amines Part of diffuse neuroendocrine systen DNES

what parts of the digestive tract are made from ectoderm

Epithelial lining of the oral cavity, salivary glands + Neuroectoderm: enteric nervous system + Neural crest: Teeth

filiform papillae common/uncommon shape keritanized/unkeratinized colour function

Filiform papillae very numerous elongated conical shape heavily keratinized gray or whitish appearance rough surface that facilitates movement of food during chewing

foliate papillae common/uncommon shape colour where

Foliate papillae consist of several parallel ridges on each side of the tongue anterior to the sulcus terminalis rudimentary in humans, especially older individuals.

pernicocious anemia

For various reasons, including autoimmunity, parietal cells may be damaged to the extent that insufficient quantities of intrinsic factor are secreted and vitamin B12 is not absorbed adequately. This vitamin is a cofactor required for DNA synthesis; low levels of vitamin B12 can reduce proliferation of erythroblasts, producing pernicious anemia. ! Stomach bypass surgery can be a cause of pernicious anemia!

functions of stomach

Func Continue dig of carbs from salivary amylase Acidify and mix with muscularis churning Begin digesting TAG with lipase Begin digesting proteins with pepsin

fungiform papillae common/uncommon shape keritanized/unkeratinized colour where

Fungiform papillae much less numerous lightly keratinized interspersed among the filiform papillae mushroom-shaped well-vascularized and innervated cores of lamina propria.

what parts of the digestive tract are made from endoderm

Gut tube epithelium and derivates (e.g. liver, pancreas)

name several infections that the oral cavity immune defenses cannot always protect against

Immune defenses in the oral cavity cannot protect against all infections. Pharyngitis and tonsillitis are often due to the bacterium Streptococcus pyrogenes. White excrescences or leukoplakia on the sides of the tongue can be caused by Epstein-Barr virus. Oral thrush, a white exudate on the tongue's dorsal surface, is due to a yeast (Candida albicans) infection and usually affects neonates or immu- nocompromised patients.

where are the non keratinized cells in the oral cavity

Nonkeratinized squamous epithelium predominates in the lining mucosa over the soft palate, cheeks, the floor of the mouth, and the pharynx, the posterior region of the oral cavity leading to the esophagus.

chief cells defining characteristics

Numerous in lower region of gastric gland Active protein secreting Lots of RER, sec. vesicles Pepsinogens- will be converted to pepsin in stomach- will degrade protein @ pH 1.8-3.5 Gastric lipase- digests lipids

what tissues make up the hard palate

Only mucosa, lamina proptia on bone for hard palate and gums

outer layer of esophagus

Outer layer is adventitia until it pierces the diaphragm, after which it is covered by a serosa

periodontal disease

Periodontal diseases include gingivitis, inflammation of the gums, and periodontitis, which involves inflammation at deeper sites, both of which are caused most commonlyby bacterial infections with poor oral hygiene. Chronic periodontitis weakens the periodontal ligament and can lead to loosening of the teeth. The depth of the gingival sulcus, measured during clinical dental examinations, is an important indicator of potential periodontal disease.

features of pylorous

Pylorous - Mucous, gastrin (stimulates contraction, secretion) - Deep pits; Shallow branched glands

3 special features of stomach

Rugae Large folds in the stomach Pits Invaginations of the mucosa (openings of glands) Gastric Glands Secrete the gastric juices

mesentery

Sheets of connective tissue which bind together the loops of the GI tract. Covered by mesothelium in both sides. Supports organs and is continuous with peritoneum

mesothelium

Simple squamous epithelial tissue which forms the surface of the serosa in the major body cavities (Pericardial, pleural, and peritoneal

what type of muscle is in esophagus

Starts with skeletal muscle then partway through smooth muscle starts when at the end of esophagus its only smooth muscle. So you don't have to constantly voluntarily swallow until the food reaches stomach the muscularis is exclusively skeletal muscle like that of the tongue.

stomach submucosa

Submucosa Dense, irregular connective tissue

Submucosa: - Esophagus

Submucosa: - Esophageal mucous glands

what separates the taste but area form the lingual tonsils

Sulcus terminalis V shaped groove that seperates papillary (bud) area and lingual tonsils

odontoblasts

Tall columnar secretory cells with secretory processes embedded in the matrix (impregnated with parallel dentine tubules). Dentine is added and then calcified. We find a thin layer of "pre-dentine" (not calcified) between the dentine and odontoblasts Neural crest

lips type of epithelium

The internal mucous surface has lining mucosa with a thick, nonkeratinized epithelium and many minor labial salivary glands. The red vermilion zone of each lip is covered by very thin keratinized stratified squamous epithelium and is transitional between the oral mucosa and skin. This re- gion lacks salivary or sweat glands and is kept moist with saliva from the tongue. The underlying connective tissue is very rich in both sensory innervation and capillaries, which impart the pink color to this region. The outer surface has thin skin, consisting of epidermal and dermal layers, sweat glands, and many hair follicles with sebaceous glands.

where are the keratinized cells in the oral cavity

The keratinized cell layers resist damage from abrasion and are best developed in the masticatory mucosa on the gingiva (gum), parts of the tongue and hard palate.

GERD

The lubricating mucus produced in the esophagus offers little protection against acid that may move there from the stomach. Such movement can produce heartburn or reflux esophagitis. An incompetent inferior esophageal sphincter may result in chronic heartburn, which can lead to erosion of the esophageal mucosa or gastro- esophageal reflux disease (GERD). Untreated GERD can produce metaplastic changes in the stratified squamous epithelium of the esophageal mucosa, a condition called Barrett esophagus.

describe muscles of the tongue

The muscularis consists of three layers: - Outer longitudinal layer - Middle circular layer - Inner oblique layer

adventitia

Thick layer of loose connective tissue containing vessels, nerves and adipose tissue, but lacking mesothelium. Where organs are bound directly to adjacent structures/organs (found in retroperitoneal organs)

serosa

Thin layer of loose connective tissue, rich in blood vessels, lymphatics, and adipose tissue, with a simple squamous covering epithelium (mesothelium). Covers peritoneal organs. Continuous with the mesentery and omentum.

carcinoid tumors

Tumors called carcinoids, which arise from enteroen- docrine EC cells, are responsible for the clinical symp- toms caused by overproduction of serotonin. Serotonin increases gut motility, and chronic high levels of this hormone/neurotransmitter can produce mucosal vasocon- striction and tissue damage.

what makes up the muscular externa in digestive system

Two or more layers of smooth muscle: - Inner layer, circularly oriented - Outer layer, of longitudinally oriented - Myenteric (Auerbach's) plexus

vallate papillae common/uncommon shape keritanized/unkeratinized colour where

Vallate(orcircumvallate)papillae largest papillae D=1 to 3 mm. 8-aligned infront of terminal sulcus. Ducts of several small, serous salivary (von Ebner) glands empty into the deep, moatlike groove surrounding each vallate papilla. provides a continuous flow of fluid over the taste buds that are abun- dant on the sides of these papillae, washing away food par- ticles so that the taste buds can receive and process new gustatory stimuli. Secretions from salivary glands associated with taste buds contain a lipase that prevents the formation of a hydrophobic film on these structures that would hinder gustation.

herpes simplex 1

Viral infections with herpes simplex 1 cause death of infected epithelial cells that can lead to vesicular or ulcer- ating lesions of the oral mucosa or skin near the mouth. In the oral cavity such areas are called canker sores, and on the skin they are usually called cold sores or fever blisters. Such lesions, often painful and clustered, occur when the immune defenses are weakened by emotional stress, fever, illness, or local skin damage, allowing the virus, present in the local nerves, to move into the epithe- lial cells

gastric pits

a simple columnar epithelium that invaginates deeply into the lamina propria. The invaginations form millions of gastric pits, each with an opening to the stomach lumen The surface mucous cells that line the lumen and gastric pits secrete a thick, adherent, and highly viscous mucous layer that is rich in bicarbonate ions and protects the mucosa from both abrasive effects of intraluminal food and the corrosive effects of stomach The gastric pits lead to long, branched, tubular glands that extend through the full thickness of the lamina propria. Stem cells for the epithelium that lines the glands, pits, and stomach lumen are found in a narrow segment (isthmus) between each gastric pit and the gastric glands. The plurip- otent stem cells divide asymmetrically, producing progeni- tor cells for all the other epithelial cells. Some of these move upward to replace surface mucous cells, which have a turnover time of 4 to 7 days. Other progenitor cells migrate more deeply and differentiate into the secretory cells of the glands that turn over much more slowly than the surface mucous cells. acid.

gastric glands

A parietal B chief, the pale things are G cells In the fundus and body the gastric glands themselves fill most of the mucosa, with several such glands formed by branching at the isthmus or neck of each gastric pit. Secretory epithelial cells of the gastric glands are distributed unevenly and release products that are key to the stomach's functions. These cells are of four major types and important properties of each are as follows: Mucous neck cells Parietal cells Chief (zymogenic) cells Enteroendocrine cells

lamina propria in digestive system consists of what

Lamina propria= loose connective tissue (some texts say otherwise but go with this)

what makes up the adventitia or serosa in digestive system

Layer of connective tissue

dentine

Made by odontoblasts (inner border). Production of dentine is limited to the pulpal surface. (90% type I collagen, 70% of wet weight is hydroxyapatite).

tissues in the tongue

Mass of skeletal muscle. Muscle fibers intersect in all three planes and are grouped into bundles, often separated by smooth muscle. Coated with mucosa (keratinized stratified squamous epithelium) and underlying lamina propria. Ventral surface: Smooth, lining mucosa Dorsal surface: Irregular, rough, papillae, at the back linguial tonsils Special features Epithelial folds = Papillae Circumvallate, Foliate, Fungiform, Filiform. Anterior 2/3. Lymphoid aggregates Mucosal crypts, tonsils. Posterior 1/3 (Lingual V)

what parts of the digestive tract are made from mesoderm

Mesentery, connective tissues, smooth muscle, blood vessels

stomach mucosa

Mucosa Simple columnar epithelium Lamina Propria - reduced to small amounts Muscularis Mucosa

mucosa of esophagus

Mucosa: - Nonkeratinized stratified squamous epithelium - Lamina propria - Muscularis mucosae (single layer of longitudinally oriented smooth muscle)

what type of epithelium is in the oral cavity

Mucosas tends to be strat squamous = oral mucosa It is sometimes keratinized and sometimes not Undergo constant shedding

cells of the fund/body and their function

Mucous cells (epithelial) Produce a protective alkaline mucous layer More acidic than the junctional areas of stomach Chief Cells - Basophilic Secrete pepsinogen & lipase precursor They are more elongated/ basal Parietal cells (oxyntic) - Acidophilic Secrete HCl and Intrinsic factor (Vit B12 absorption) More centrally located nuclei Entero-endocrine cells (G Cells) - Require special stains - Among Chief cells - Secrete a variety of peptide hormones (e.g. Serotonin=increases gut motility)

what is the difference in glands in the pylorous

Mucous cells, Chief Cells, Parietal cells - Same cells as before, but different quantities. Glands produce mucous to protect duodenum Entero-endocrine cells - High concentration of gastrin (G cells produce Gastrin to increase gastric motility and secretion) In the cardia and pylorus regions of the stomach, the mucosa also contains tubular glands, with long pits, branch- ing into coiled secretory portions, called cardial glands and pyloric glands (Figure 15-21). These glands lack both pari- etal and chief cells, primarily secreting abundant mucus.

mucus neck cells distinguishing features

Mucous neck cells are present in clusters or as single cells among the other cells in the necks of gastric glands and include many progenitor and immature surface mucous cells (Figure 15-17). Less columnar than the surface mucous cells lining the gastric pits, mucous neck cells are often distorted by neighboring cells, but they have round nuclei and apical secretory granules. Their mucus secretion is less alkaline than that of the surface epithelial mucous cells.

stomach muscularis externa

Muscularis Externa Three layers of muscle (Obliq; Circ; Long)