Digestive System P.1

Stomach

S: regions:


1. fundic
2. cardiac
3. pyloric

F: processes food for digestion, breaks down food into chyme

L: kills all living cells

Small Intestine

S: Regions: Duodenum (Brunner’s glands), Jejunum, and Ileum (Peyer’s patches)

F: nutrient absorption

L: The small intestine is located in the abdominal cavity, between the stomach and the large intestine.

Large intestine

S: Layers: mucosa, submucosa, Muscularis Externa, serosa

F: site of water removal, elimination of waste

L: The large intestine is located in the lower part of the digestive system, specifically in the abdominal cavity. It begins at the end of the small intestine and ends at the anus.

Salivary glands

S: enter the oral cavity through a group of duct; composed of clusters of secretory cells that produce and secrete saliva.

F: secrete enzymes, mucus, and water, produce alpha amylase (digestive enzyme), secrete saliva

L: under the tongue, below and in front of ear, near the mandible

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Parotid Gland

S: compose completely of serous secretory units

F: salivary glands (secrete enzymes, mucus, and water), secrete saliva

L: located below and in front of the ear

Submandibular or submaxillary gland

S: composed of mixed serous and mucous with serous demilunes

F: salivary glands (secrete, enzymes, mucus, and water), secrete saliva

L: near the mandible, beneath the floor of the oral cavity

Sublingual

S: composed of mucous secretory unit

F: salivary glands (secrete enzymes, mucus, and water), secrete saliva

L: located anterior to the submandibular gland, beneath the tongue

Liver

S: largest gland in the body

F: secretes bile, receives all blood draining from the intestines (removes toxic substances and aids in fat metabolism)

L: located beneath the diaphragm

Gall bladder

S: hollow, pear shaped organ

F: stores bile

L: located below the liver

Pancreas

S: elongated organ; has exocrine and endocrine glands

F: secretes digestive enzymes

L: located in the curve of the duodenum

Nasopharynx

S: lined by pseudostratified columnar epithelium

F: part of the respiratory system, air passageway

L: above and behind the soft palate

oral pharynx

S: lined by stratified squamous epithelium

F: passageway for the digestive respiratory system; carries air, food and fluid down from the nose and mouth

L: posterior to the oral cavity

Laryngeal pharynx

S: lined by stratified squamous epithelium

F: passageway for the digestive and respiratory; acts as the passageway for air, food, and liquid

L: from the oral pharynx to the epiglottis

Masticatory mucosa

S: composition: keratinized stratified squamous epithelium, parakeratinized stratified squamous epithelium, underlying connective tissue

F: a type of oral mucosa that covers the hard palate and gingiva. Its function is to withstand the mechanical stresses of mastication and protect the underlying structures.

L: gingiva and hard palate

Lining mucosa

S: 3-layered nonkeratinized stratified squamous epithelium: stratum basal, stratum spinous, and stratum superficiale

F: secrete mucus, which helps to protect and lubricate the tissues, as well as to trap and remove foreign particles and microorganisms. may also play a role in absorption and secretion of various substances.

L: everywhere else except dorsal surface of tongue; lines various organs and body cavities, such as the respiratory, digestive, and urinary tracts

Specialized mucosa

S: composition: nonkeratinized stratified squamous epithelium, keratinized stratified squamous epithelium, contain taste buds

F: the lining of specific organs in the body that have unique functions. For example, the mucosa in the stomach secretes acid and enzymes to aid in digestion, while the mucosa in the respiratory tract produces mucus to trap foreign particles and protect the lungs. varies depending on the organ it lines.

L: lining of the stomach, small intestine, colon, uterus, and Fallopian tubes

nasal cavity, trachea, and bronchi

filiform papilla

S: high conical structure, inclined in an anterior-posterior direction; cone of lamina propria covered by a keratinizing epithelium, cornified tip

F: rasping

L: cover most of dorsal surface of tongue

Circumvallate papillae

S: large c.t. papillum, von ebner’s glands located in the grooves, largest papillae, surrounded by a moat-like grove

F: carry taste buds

L: dorsal surface of the rear of the tongue

Foliate papilla

S: ridge-like shape, separated by deep grooves

F: carry taste buds

L: sides of the rear half of the tongue

Von’s ebner’s glands

S: serous glands

F: produced watery secretions to wash out the groove

L: located at the base of the groove of the circumvallate

Fungiform papillae

S: club or mushroom shaped with a flattened surface; club-shaped extension of the lamina propria, richly supplied with blood → red color

F: carry taste buds

L: dorsal surface, occurring singly among the filiform papillae

Esophagus

S: muscular tube (25 cm), beginning of the tubular portion of the gut

F: propels ingested food from the pharynx to the stomach

L: muscular tube that connects the pharynx (throat) to the stomach. It is located in the neck and chest region of the body.

Stomach

S: expanded muscular sac; layers mucosa, submucosa, Muscularis Externa, serosa

F: acts as a reservoir for ingested food, mixing and partial digestion of food, kill living cells, production of intrinsic factor

L: the upper left part of the abdominal cavity, just below the diaphragm.

Pyloric valve

S: muscular sphincter

F: control movement of chyme into the duodenum, derive from Muscularis Externa

L: stomach

Rugae

S: folds of the muscoa and submucosa

F: flattens out as the stomach distends

L: stomach

Foveolae

S: lined by mucous-secreting surface mucous cells, irregular shaped depressions in the surface of the stomach’s mucosa

F: secrete mucus that protects the stomach lining from the acidic environment of the stomach. The mucus also lubricates the stomach lining, allowing food to move more easily through the digestive system.

L: stomach

Gastric glands

S: simple, branched tubular glands of the mucosa

F: producing gastric juice, which contains hydrochloric acid, pepsinogen, and mucus. aid in the digestion of food in the stomach.

L: extend from the bases of the gastric pits of the stomach

Pyloric

S: thickness of pits = thickness of glands (1:1)

F: opens and closes; allows partly digested food and other stomach contents to pass from the stomach to the small intestine.

L: region adjacent to the pyloric sphincter

Cardiac

S: thickness of pits = thickness of glands (1:1), all mucous cells

F: food and liquids pass through the cardiac to enter the stomach from the esophagus

L: region just around the esophageal orifice

Fundic

S: variety of cell types, thickness of pits << thickness of glands (\~1:4)

F: stores gas from digestion; stores and breaks down food

L: occupy most of stomach (fundus and body)

Gastric mucosa

S: simple columnar epithelium, lamina propria, 2-3 layers of Muscularis mucosae

F: lubricate the food masses in the stomach and facilitate movement within the stomach; create a protective barrier to protect the stomach wall from acid and digestive enzymes

L: stomach

Cardiac glands

S: two types of cells: mucous-secreting cells; Enteroendocrine cells, small, morphologically indistinct

F: secrete mucous, coats stomach and prevents self-digestion

L: cardiac region of the stomach

Fundic glands

S: composed of several cells:


1. mucous neck cells
2. parietal (oxyntic) cells
3. chief cells
4. Enteroendocrine cells
5. undifferentiated stem cell

F: production of digestive juice

L: found in most of the stomach

mucous neck cells

S: basal nucleus, unstained cytoplasm

F: secrete soluble mucus = mix with food → chyme

L: located in the neck

Parietal (oxyntic) cells

S: large, triangular cells; centrally located nucleus; eosinophilic cytoplasm

F: secrete HCl and intrinsic factor

L: scattered from the neck down

Chief cells

S: centrally located nucleus; basophilic, granular cytoplasm, secretory cells

F: secrete pepsinogen

L: concentrated in the base of the gland

Enteroendocrine cells/ enterochromaffin cells/ argentaffin cells/ argyrophil cells/ amino precursor uptake and decarboxylation cell

S: lumen, Golgi complex, secretory granules, basal lamina

F: hormone secreting cells, produce >20 peptide and polypeptide hormones

L: located throughout the digestive tract in the crypts of the Lieberkuhn

undifferentiated stem cells

S: do not have tissue

F: go through a process called differentiation and create special types of cells

L: located in neck region

pyloric region

S: mucous cells (principal cell type), Enteroendocrine cell, parietal cells- may be present in small numbers, undifferentiated stem cells

F: opens and closes; allows partly digested food and other stomach contents to pass from the stomach to the small intestine.

L: stomach

small intestine

S: layers: mucosa, submucosa, muscularis, serosa

F: completing the process of digestion, selective absorption of molecules across the epithelium into the tissue fluid/ blood supply of the c.t.

L: between the stomach and the large intestine

Meissner’s plexus of nerves

S: neurons

F: ganglia of the autonomic nervous system

L: submucosa of the small intestine

Peyer’s patch

S: accumulation of lymphatic nodules in the c.t. on one side of the ileum

F: keep intestinal flora and pathogens at bay; preventing a large number of infections

L: Ileum of small intestine

Plicae circularis (valves of Kerckring)

S: permanent transverse (circumferential) folds of the submucosa covered by mucosa

F: increases surface area of small intestine for absorption

L: small intestine

villi

S: finger-like projections of the mucosa covered by simple columnar epithelium

F: increases surface area of small intestine for absorption

L: small intestine

Microvilli

S: cylindrical projection of the apical plasma membrane of absorptive cells (enterocytes), core of microfilaments

F: increase the SA for absorption

L: small intestines

Enterocytes

S: intestinal absorptive cells

F: absorb nutrients and other solutes, secrete glycoprotein enzymes (involved in digestion and absorption), have microvilli to increase SA and to promote absorption

L: mucosa of small intestine

Goblet cells

S: basally located nucleus and cytoplasm filled with mucin granules

F: secrete water soluble mucus; serves as lubricant, protective coating, and hydrating agent

L: small intestine, large intestine

Lymphocytes

S: small white blood cells with an ovoid or kidney shaped nucleus that stains purple

F: helps body fight disease and infection

L: often seen wandering between the epithelial cells of small intestine

Villi

S: projection of the mucosa covered by simple columnar epithelium

F: core of lamina propria, increase SA of small intestines for absorption

L: throughout the small intestine

Lacteal

S: central lymphatic vessel

F: drains excess fluid

L: villi of mucosa of small intestine

Smooth muscle cells

S: accompany the lacteal up from the Muscularis mucosae

F: motility (enhances diffusion); helps with digestion

L: stomach and intestines

Myofibroblasts

S: span the width of the villus

F: contribute to shortening and movement of the villus

L: villi of the mucosa of the small intestine

Crypts of Lieberkuhn

S: tubular glands formed from the mucosa of the small intestine in between the bases of the villi

F: cells secrete intestinal juice

L: small intestine (mucosa), rectum

Paneth cells

S: pyramid shaped cells located in the bases of glands, contain eosinophilic zymogen granules

F: secrete lysozyme = antibacterial enzyme

L: jejunum of small intestine

Enteroendocrine cells

S: specialized cells

F: hormone secreting cells; secretes: cholecystokinin, secretin, gastric inhibitory peptide, and gastrin

inhibits gastric secretion and motility, stimulate pancreatic and gall bladder activity

L: crypts of Lieberkuhn

M (microfold) cells

S: modified enterocytes covering lymphatic nodules

F: pass antigens across the epithelium

L: crypts of Lieberkuhn

GALT

S: cells of the immune system

F: protect body from foreign antigens and pathogen allow tolerance to commensal bacteria and dietary antigens

L: may be present anywhere in the intestine, connective tissue of the digestive tract

Duodenum

S: 25 cm, characterized by the presence of submucosal (Brunner’s) glands

F: food gets broken down, pathway through which digestive enzymes from pancreas enter the digestive tract, space through which food travels to jejunum

L: Region of the small intestine

Brunner’s glands

S: submucous glands, tubuloalveolar glands

F: secrete neural and alkaline glycoproteins and bicarbonate ions

L: in the submucosa of the duodenum of the small intestine

Jejunum

S: 2.5 m, characterized by the absence of submucosal glands and the absence of Peyer’s patches

F: helps to further digest food coming from the stomach

L: region of the small intestine

Ileum

S: 3.5 m, characterized by the presence of Peyer’s patches

F: helps to further digest food

L: region of the small intestine

Large intestine

S: Layers: mucosa, submucosa, Muscularis Externa, serosa

F: absorption (recovers substances added to ingested food including electrolytes and water) and excretion of solid waste (defecation)

Goblet cells

S: mucus filled, white

F: secrete mucus → lubricates the bowel → facilitated movement of fecal material

L: small intestine, large intestine

intermediate cells

S: morphologically indistinct

F: serve as stem cell

L: located in lower third of the crypts of large intestine

Collagen table

S: thick layer of collagen and proteoglycans

F: separates the epithelium from underlying fenestrated capillaries

L:

Perocryptal fibroblast sheath

S: helically arranged around the crypts

F: secrete reticular fibers in a helical pattern

L: Lamina propria of mucosa of the large intestine

Muscularis Externa of large intestine

S: inner circular layer (thrown into semilunar folds), gives rise to the internal anal sphincter; auerbach’s plexus (ganglia of the autonomic nervous system); outer longitudinal layer

Teniae Coli Muscles

S: three separate longitudinal bands of muscle

F:

L: extend from the ascending to the sigmoid colon

Appendix

S: thin, finger-like extensions of the cecum; reduced amount of crypts; characterized by the presence of abundant lymphatic nodules, muscularis externa (two complete layers)

F: maintain the gut flora by protecting good bacteria that are important in digestion

L: large intestine, cecum

Cecum

S: dilated portion of the rectum, longitudinal folds in the wall, upper portion (transverse rectal folds), lower portion anal columns (rectal columns of Morgani) \[depressions between the columns= anal sinuses (rectal sinuses)\]

F:

L:

Rectal columns of Morgani

S: anal column

F:

L: cecum

Rectal sinuses

S: anal sinuses, depressions between anal columns

F: separates the anal columns from one another

L:

Anal Canal

S: upper portion has simple columnar epithelium,

transitional portion has stratified columnar, lower portion has unkeratinized stratified squamous proximally and keratinized stratified squamous distally

F: the maintenance of fecal continence and defecation; maintenance of control of bowel movements and discharge of feces (pooping)

L: large intestine

Anal Glands

S: simple, branched tubular mucus-secreting glands, secretory units extend into the submucosa and muscularis, distal portion lined by stratified squamous epithelium

F: lubrication

L: large intestine

Circumanal glands

S: composed of lobules that are densely packed with large polyhedral cells

F:

L: located in the epidermis around the anal orifice

hemorrhoidal veins

S: submucosal veins

F: anal continence, control bowel movement

L: part of the rectal venous plexus

Anal sphincter

S: internal anal sphincter- smooth muscle, derived from the Muscularis Externa

external anal sphincter- striated muscle, derived from muscle of the perineum

F: controls emptying of the bowel

L: large intestine

Mitochondria

S: cellular organelle

F: associated with the folds in the basal plasma membrane of striated duct epithelial cells

L: cytoplasm

Alpha amylase

S:

F: digestive enzyme produced by salivary glands; causes degradation of starch molecule

L: saliva in the mouth

Parakeratinized

S: a stratified squamous epithelium whose superficial cells are keratinized and nucleated

F:

L: dorsal surface of the tongue

Sublingual

S: composed of mucous secretory unit

F: the secretions in humans enter the mouth through a pair of papillae located on either side of the frenulum

L: under the tongue

Immunoglobulin A

S: antibodies (immunoglobulins)

F: protects the mucosal tissues from microbial invasion and maintain immune homeostasis with the microbiota

L: present in saliva

M cells

S: epithelial cells

F: overlie the large lymphatic nodules in the intestines that digest microorganisms and macromolecules before secreting the antigens in the vicinity of CD4+ T-cells

L: the intestines

Teniae coli

S: the Muscularis Externa thickened into three prominent bands of muscle

F: suspension cables upon which the circular muscle arcs are suspended; facilitating efficient contraction of the circular muscle

L: colon

Hemorrhoidal veins

S: the enlarged submucosal veins

F: anal continence, controlling bowel movements

L: in the submucosal veins of the anal canal

Isthmus

S: short segment

F: where cell replication occurs

L: between the gastric pits and the gastric glands

Ruga

S: the longitudinal submucosal fold

F: allow for expansion of the stomach after consumption of foods and liquids

L: stomach

Inner circular layer of the Muscularis Externa

S: inner thick predominant circular muscle coat

F: responsible for segmentation of the intestinal contents

L: muscularis externa

Features that increase the surface area for absorption of the small intestine

1. villi
2. microvilli
3. plicae of circularis

Chyme

S: the pulpy fluid, mixing ingested food with gastric secretions

F: increases the surface area of food by breaking it down into smaller components; stimulates digestive glands to secrete their respective solutions

L: produced in stomach

Lacteal

S: the lymphatic capillary

F: absorb large molecules of fats and lipids from the small intestine

L: located in the center of a villus