Digestive System: The Accessory Organs

bile

an emulsifying agent facilitating the hydrolysis of lipids by pancreatic lipases.

Histological features of the uvula

SSNK + CT

Glisson's capsule is associated with _____________(organ). Full morphology?

liver; DICT

histological features of the soft palate

--> muscosa= SSNK --> lamina propria= DICT --> rugae; grooves on top of the roof --> submucosa = LOCT and mostly DICT --> cancellous bone

Accessory structures of the digestive system

1) Oral cavity and accessory parts (lips, teeth, tongue, cheeks, uvula, tonsils, soft and hard palette, epiglottis) 2) salivary glands 3) Liver 4) Gall bladder 5) Pancreas

Majority salivary glands (type of secretion & full morphology & corresponding duct)

1) Parotid glands --> secretes serous substances (enzymes: amylase and lysozymes) --> full morphology: compound acinar --> corresponding duct: Stensen which opens into vestibule opposite the second molar 2) Submandibular glands --> secrete both serous and mucous substances -full morphology: compound tubuloacinar --> corresponding duct: Wharton which opens into either side of the lingual frenulum 3) sublingual glands --> secrete mostly mucous substances --> Full morphology: compound tubular --> corresponding duct: Rivini which opens onto the floor of the mouth. NOTE: all glands has a branched duct system consisting of both a intralobular (w/in lobule) and interlobular (outside lobule) ducts

characterisitcs of liver lobules

1) Pentagon/ hexagon shaped cylinder made of hepatocytes arranged in thin plates separated by sinusoids --> both hepatocytes and sinusoids radiate out of the center of the lobule 2) Centrilobar venule or terminal hepatic venule --> vein found in the center of each lobule 3) Portal triad at each outer corner of lobules

structures of the alimentary canal or gastro-intestinal tract

1) Pharynx 2) esophagus 3) stomach 4) small intestine 5) large intestine 6) anus

liver functions

1) bile formation & secretion 2) detoxification 3) metabolism of food (fat, carbohydrates, protein) 4) storage of iron, glycogen and vitamins A, B12, and D 5) Productions of some plasma proteins and hormones 6) site of fetal hematopoeisis 7) glycogen production by hepatocytes

function of hepatocytes

1) blood circulation --> hepatic portal vein & hepatic artery 2) hepatocytes + phagocytic reticuloendothelial cells work together to remove bacteria, worn out RBCs (sensent RBCs) from the blood --> RBCs have a life span of 120 days 3) remove and store some vitamins 4) detoxify poisons 5) forms bile 6) stores glycogen

functions of saliva

1) cleansing action on the teeth 2) moistens and lubricates food during mastication and swallowing 3) dissolves certain molecules so that food can be tasted 4) initiates the chemical digestion of starches through the action of amylase, which breaks down polysccharides

cells that line the sinusoids

1) endothelial cells --> 'squamous' cells lining the endothelium 2) Kupffer cells aka reticuloendothelial cells --> monocyte-macrophage defense system & removal of old RBCs 3) Stellate/ Ito cells or hepatic lipocytes --> produce lipid droplet with vitamin A and produce ECM and collagen

components of the portal triad

1) hepatic portal aka portal vein 2) hepatic artery 3) bile duct

functions of the digestive system

1) ingestion 2) digestion 3) motility 4) secretion 5) absorption 6) elimination 7) regulation

location of absorption

1) mouth (under the tonge) 2) Stomach (when extremely dehydrated)

subdivisions of the right lobe of the liver

1) right lobe proper 2) caudate lobe 3) Quadrate lobe

cells that make up a duct system

1) serous secreting cells --> they are seromucous cells because they secrete both proteins and considerable amount of polysaccharides . --> resemble truncated pyramids and abundant apically situated secretory granules rich in ptyalin (salivary amylase). --> the basal aspects of the lateral cell membranes from tight junctions with each other. --> apical to the tight junctions, intercellular canaliculi communicate with the lumen. --> the plasmalemma basal to the tight junctions forms many processes that interdigitate with those of neighbouring cells. 2) mucous secreting cells --> similar in shape to the serous cells. --> their nuclei are also basally located but are flattened instead of being round --> have fewer mitochondria --> less extensive rough endoplasmic reticulum --> considerably greater golgi apparatus --> indicative of the greater carbohydrate component of their secretory product. --> the apical region of the cytoplasm is occupied by abundant secretory granules. --> intercellular canaliculi --> processes of the basal cell membranes are much less extensive than those of serous cells. 3) serous demilunes 4) myoepithelial cells -->they are contractile cells by they are not muscle cells --> responsible for allowing the gland cells to secrete. --> found proximal to the glandular cells. --> shares the basal laminae of the acinar cells --> have a cell body that houses the nucleus and several long processes that envelop the secretory acinus and intercalated ducts. The cytoplasmis proceses, which form desmosomal contacts with the acinar and duct cells are riich in actin and myosin which resemble smooth muscle cells. --> cell body houses a small complement of organelles in addition to the nucleus and make hemidesmosomal attachments with basal lamina. 5) intercalated ducts --> considered an intralobular ducts --> smaller than striated ducts --> dont have prominant lumen 6) striated ducts --> 2 layers of cells (striated columnar/ cuboidal)

flow of bile

1) synthesized by hepatocytes 2) secreted into canaliculi (fine channels formed by the plasma membrnae of adjacent hepatocytes) 3) merge into canals of Hering 4) terminates at the bile ducts in the portal tracts 5) gallbladder 6) pancreas hepatocytes --> canaliculi --> canals of Hering -->bile ducts in portal triad --> gallbladder --> pancreas

histological features of the hard palate

2 palatine bones + 2 maxilla

how is the tongue divided

2/3 anterior --> contains papillae (filiform, foliate, fungiform, circumvallate) --> keratinized; if you eat a lot of roughage = more keratinized 1/3 posterior --> SSNK --> falls straight into the pharynx --> contains lymphoid tissue (lingual tonsil) --> waldeyer's ring; made up of lingual tonsil, palatine tonsils and adenoids

Portal tracts

CT in the liver --> supports the portal triad

Mastication

DEF: chewing --> involves coordinated movements of the mandible, teeth, lips, tongue

histological features (full morphology) of the cheeks

Epithelium = SSNK Musculature = skeletal

pathological vs normal features of the liver

Gross evaluation 1) weight --> normal = ~ 1.5 kg --> pathological = significantly smaller 2) surface --> normal = glistening --> pathological= matte; bumps on it (looks like it has chicken pox on it) 3) colour --> normal = pink/red --> pathological = brown Microscopic evaluation normal= no sepatae pathological = septae present with clear distinct lobules

flow of blood in the liver

Hepatic portal vein HPV) + hepatic artery (HA) --> terminal end of HPV & HA in portal tracts --> sinusoids --> centrilobar venule (terminal hepatic venule) --> hepatic vein --> heart

histological features of the gallbladder

Mucosa --> Rugae= mucosal folds --> surface epithelium = simple columnar with microvilli --> lamina propria= LOCT Fibromuscular coat --> Submucosa = LOCT, vascular, elastin fibers, lymphatic vessels --> Muscularis externa= smooth muscle Perimuscular CT layer --> Serosa/ Adventitia = DICT

Gallbladder (location & function)

Shape/ Size: --> pear shaped sac with neck, body, fundus --> 7-10 cm long --> can hold 30-50 mL of bile location: found underside of the liver, in close proximity to the liver and the beginning part of the small intestine (duodenum) and proximal to the pancreas function: --> stores bile --> concentrates the volume of bile 5- 10 fold --> ejection of concentrated bile into the duodenum

function of canaliculi in liver

allows for passage of the bile that is secreted by the hepatocytes which drains into the central canal of the lobule

histological features of the lips

external surface = SSK w/ sebaceous and sweat glands and hair follicles transitional zone aka vermillion (b/w exterior and interior) = SSK and occasional sebacceous glands (no sweat glands or hair follicles) vestibule (pat when you stretch your lips aka the dip between your lips and teeth aka proximal to the teeth = SSNK + lamina propria core of the lips= skeletal + glands (serous and mucous secretions)

distinguishing features of filiform vs fungiform vs foliate vs circumvallate

filiform = pointy and narrow, long, slender, numerous --> does not have taste buds fungiform= looks like a mushroom --> has tastebuds foliate= shaped like a leaf, longitudinal furrows --> has many tastebuds Circumvallate= shaped as a much larger fungiform papillae --> will have a lot of tastebuds --> contains moat like structure that is filled with saliva NOTE: all papillae are covered by SSNK

extrahepatic biliary tree

flow of bile from outside the liver 1) Bile ducts in portal tracts 2) right and left hepatic ducts 3) Common hepatic duct (leave the liver) 4) gallbaldder 5) cystic duct (drains gallbladder) to form common bile duct 6) common bile duct is joined by pancreatic duct to form ampulla of vater before entering the duodenum Bile flow from liver --> gallbladder --> pancreas

functional unit of liver

hepatocytes --> polyhedral (no distinct shape) with round nuclei and prominent nucleoli (sometimes exhibiting binucleation) --> connects to each other via canaliculi to form plates --> contains lipofuscin (wear and tear pigment) --> supported by reticular CT

The endocrine part of the pancreas secretes _____________ , while the exocrine part of the pancreas secretes ______________.

hormone; enzyme

purpose of 4 intrinsic muscles in the tongue vs purpose of 4 extrinsic muscles

intrinsic = defines the shapes of the tongue --> not attached to any bone --> contraction for mastication extrinsic = defines the position of the tongue --> anchored to the bone --> contraction for deglutination, speech, sticking out, depressing the tongue.

largest gland in the body

liver

liver

location: lies beneath the diaphragm in the right hypochondrium lobes: has a left and right lobe

location of earliest part of absorption

mouth (underneath the tongue)

full morphology of the epithelium of the oral mucosa

mucosa = SSNK lamina propria = DICT --> normally this would be LOCT but because of the mechanical activites that goes on int he mouth, you dont want the epithelium to come off.

when breathing, the epiglottis closes the ___________. during deglutition, the epiglottis closes the ____________ to prevent ____________

oropharynx; trachea; pneumonia

how to distinguish between parotid gland and pancreas microscopically

parotid gland only have compound acinar units= exocrine portion pancreas has both exocrine and endocrine portions. mostly exocrine --> compound acinar --> intralobular ducts --> interlobular ducts endocrine = clump and cord --> embedded in between exocrine units --> Alpha cells- glucagon --> beta cells - insulin --> delta cells --> polypeptide cells

falciform ligament

separated the left and right lobes

serous vs mucous secretion

serous secretion -->secretes enzymes (amylase and lysozymes) --> moistens the food mucous secretion --> binds the food bolus ready for deglutition --> secretes mucinous substances (inorganic ions, anitbodies) NOTE: saliva is made up of these two secretions

pancreas

size: ~ 15cm long colour; greyish pink gland location: runs from the duodenum, behind the stomach and to the spleen. specific cells: pancreatic islets/ islets of Langerhans (constitutes 2% of the pancreas) --> secretions go directly to the capillaries. --> duct system terminates at the pancreatic duct --> lobulated by septae --> intralobular ducts --> interlobular ducts --> Alpha cells- glucagon --> beta cells - insulin --> delta cells --> polypeptide cells

sulcus terminalis vs lingual frenulum

sulcus terminalis= divides between the anterior 2/3 and the posterior 1/3 --> main area that provides the ability to taste lingual frenulum = membrane anchoring tongue to the floor of the mouth.

deglutition

swallowing

sphincter of Oddi

two types: 1) Choledochal sphincter ; controls the concentration of bile in the gall bladder --> when close, concentration of bile in gall bladder takes place 2) Pancreatic sphincter ; allows the bile to flow at a calculated amount per digestion.