Digestive P.2

Liver

S: a large gland made up of parenchyma composed of hepatocytes, lobule structure, central vein

F: the hepatocytes that make up the liver have dual secretory and metabolic functions, exocrine secretions (secretory product = bile), endocrine secretions (secreted into blood: albumin, lipoproteins, non-immune alpha and beta globulins, prothrombin, glycoproteins, glucose, triiodothyronine)

L: beneath diaphragm, on top of stomach, right kidney and intestines

Bile

S: made up of: bile salts, cholesterol, phospholipids, bilirubin glucoronide, feces, and electrolytes

F: secretion of the exocrine in liver

L: stored in gallbladder

Bile salts

S: emulsifying agents for lipids

F: makes lipids in the small intestine soluble in tissue fluid and blood

L: reabsorbed in the intestine and recycled by hepatocytes in the liver, bile

bilirubin glucoronide

S: end-product of hemoglobin breakdown, bilirubin detoxification product

F: gives bile and fecal matter their color

L: excreted with feces

Albumin

S: protein

F: responsible for blood osmotic pressure

L: made by liver

Prothrombin

S: protein

F: precursor to thrombin

L: made by liver

Triiodothyronine

S: deiodination product of thyroid hormone, more potent than the original hormone

F: plays vital roles in the body’s metabolic rate, heart and digestive functions, muscle control, brain development and function, and the maintenance of bones

L: secret into bloodstream by the thyroid gland

Gilson’s capsule

S: dense connective tissue, partially covered by a mesothelium

F: covers the surface of the lobes of the liver

L: surface of the lobes of the liver

Septa

S: composed of loose connective tissue

F: penetrate the lobes along with blood vessels

L: encase lobules of liver

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Parenchyma

S: composed of hepatocytes

F: functional portion of the liver

L: liver

hepatocytes

S: organized into plates of contiguous cells → appear as two dimension “cords” in microscopic section

F: primary functional cells of the liver

L: liver

Portal area

S: has the branches of portal vein, hepatic artery, interlobular bile duct, and lymphatic vessel

F: a space marking the corners of the classic lobules

L: liver

Hepatic Portal vein

S: the largest vessel in the portal area, large lumen and thin wall of endothelial cells and c.t.

F: brings in venous blood draining from the digestive tract, containing: dissolved nutrients and toxic substances - degrade in the liver

drains blood from the liver

provides 75% of the blood supply to the liver

L: portal area of liver

Hepatic artery

S: small diameter, wall of endothelial cells and smooth muscle

F: pathway for oxygenated blood, provides 25% of the blood supply to the liver

L: portal area of liver

Interlobular duct

S: variable in size, lined by simple cuboidal epithelium

F: secretes fluid with a high concentration of sodium bicarbonate that serves as buffer for acids arriving in the duodenum from the stomach

L: small intestine

Space of mall

S: spaces in the portal connective tissue

F: where lymph collects

L: liver

Portal triad

S: branches of the portal vein, hepatic artery, and bile duct

F: transportation system for blood, nutrients, and gases

L: found in the portal area of the liver

Hepatocytes

S: polygonal cells with centrally located nuclei, organized into plates of cells (chords)

F: primary functional cells of the liver, detect damaged erythrocytes

L: exposed surfaces face sinusoids, bathed by blood in the sinusoids, surfaces in contact with other cells, intercellular space sealed by junction

Sinusoids

S: lined by a discontinuous layer of endothelial cells that form a very leaky lining because: cells have fenestrations, there are large gaps between cells, the basal lamina is discontinuous

F: allows fluid from the blood to bathe the exposed surface of the hepatocytes, allows erythrocytes to come into direct contact with hepatocytes

L: irregularly shaped spaces between the plates of hepatocytes

space of disse

S: space between the endothelial cells and apical surfaces of the hepatocytes

F: occupied by hepatocyte microvilli which increase surface area for absorption, creates a protected space into which hepatocytes absorb molecules and secrete them into the blood

L: liver

Lipocyte

S: adipose cell, Ito cell

F: store vitamin A, may secrete type III collagen → reticular fibers

L: located in space of disse

Bile canaliculus

S: a dilation of intercellular space between the lateral surfaces of adjacent hepatocytes, formed by plasma membrane of adjacent cells, bounded by zonula collides junctions → non-leaky seal, form an anastomosing network

F: where hepatocytes secrete bile

L: connects to the interlobular bile duct

bile ductules (canals of hering)

S: lined by cuboidal epithelium

F: collect bile from numerous canaliculi

L: flow into the interlobular bile ducts of the portal canals

Hepatic sinusoids

S: irregular, endothelial lined space between the sheets of hepatocytes

F: arterial (oxygenated) and venous (oxygen-depleted) blood mix in the sinusoids, venous blood carrying solutes also mix with the arterial blood

L: liver (between sheets of hepatocytes)

Central vein (terminal hepatic venule)

S: terminal hepatic venule

F: drain blood from the sinusoids

L: liver

Sublobular vein

S:

F: collect blood from several central veins

L: liver

Gall bladder

S: hollow, pear-shaped organ adherent to the posterior portion of the liver

Wall= three layer: mucosa, Muscularis Externa, adventitia/serosa

F: stores and concentrates bile

L: adherent to the posterior portion of the liver

Cystic duct

S: short duct

F: bi-directional transport, carries bile to and from gall bladder; joins gallbladder to common hepatic duct

L: liver

Common bile duct

S: very thin tube, about 10-12.5 cm

F: carries bile from the gall bladder and the liver to the pancreas

L: liver

Duodenal papilla (of Vater)

S: common bile duct joins the pancreatic duct at the ampulla of vater, just proximal to the papilla; papilla passes through the wall of the duodenum

F: regulation of bile flow

L: duodenum

Sphincter of Boyden

S: muscular sphincters of smooth muscle

F: when closed forces bile to go to gall bladder, when open allows bile to flow into the ampulla of vater

L: located on the common bile duct

Sphincter of Oddi

S: muscular sphincter of Smooth muscle

F: controls entry of bile and pancreatic secretions into the duodenum

L: located proximally to the papilla of vater

Pancreas

S: elongated organ

F: Dual exocrine and endocrine functions

exocrine = secretion of digestive enzymes into the the pancreatic duct system

endocrine = secretion of hormones into capillaries

L: adjacent to duodenum, tucked under the liver

Exocrine pancreas

S: elongated organ

F: exocrine: secretion of digestive enzymes into the pancreatic duct system

Ex: trypsin, chymotrypsin, elastase, carboxypeptidase, phospholipase, lipase, amylase, cholesterol esterase, ribonuclease, deoxyribonuclease

L: tucked under the liver

Endocrine pancreases

S: elongated organ

F: secretion of hormones into capillaries

i.e: insulin, glucagon, somatostatin, vasoactive intestinal peptide, pancreatic polypeptide, secretin, motion, substance P

L: tucked under the liver

Islets of Langerhans

S: aggregations of endocrine cells surrounded by exocrine secretory units

Made up of:

A (alpha) cells, B (beta) cells, D (delta) cells, minor cells

F: produces hormone to be used by pancreas

L: pancreas

A (alpha) cells

S: 15-20% of cells

F: secrete glucagon

L: islets of langerhans

glucagon

S: 29 amino acid polypeptide

F: stimulates release of glucose from cells into the blood, stimulates conversion of glycogen to glucose

L: pancreas

B (beta) cells

S: 70% of cells

F: secrete insulin

L: islets of langerhans

D (delta) cells

S: 5-10% of cells

F: secrete somatostatin

L: islets of langerhans

minor cells

S: 5% of cells

F: secrete other substance

L: islets of langerhans

Acinar secretory cells

S: typical serous secretory cells, wedge-shaped with a rounded nucleus in the basal half of the cell, basophilic cytoplasm, acidophilic zymogen granules in apical cytoplasm, contain extensive perinuclear rough ER and a prominent apical Golgi

F: synthesize and secrete almost all of the digestive enzymes active in the lumen of the small intestine which are necessary for nutrient digestion

L: exocrine pancreas

Centroacinar cells

S: small epithelial cells in the center of the acinars

F: form the beginning of duct system, allow contact with other cells

L: in the center of the acinar

Intercalated ducts

S: small ducts that drain a single secretory unit, lined with low simple cuboidal epithelium

F: cells also secrete: water, bicarbonate, sodium

Intralobular collecting ducts

S: lined by simple low columnar epithelium, larger ducts are sheathed by a prominent layer of septal c.t.

F: carry secretions to oral cavity

L: located within a single lobule, pancreas

interlobular duct

S: side branches of the main duct(s), lined by simple columnar epithelium

F: buffer acid arriving in the duodenum from the stomach

L: located within the interlobular septa

Pancreatic duct

S: lined by simple to stratified columnar epithelium

F: may contain mucus-secreting goblet cells, may be associated with mucus glands

L: runs the length of the pancreas, terminates at the duodenal papilla of vater

secretin

S: hormone

F: stimulates duct cells to produce water and bicarbonate

L: produced in duodenum

Cholocystokinin

S: linear peptide that is synthesized as a preprohormone

F: stimulates acinar cells to secrete enzyme

L: produced in duodenum

Kupffer cells

S: macrophages, black patches indicated in microscope

F: phagocytose carbon particles

L: hepatic sinusoids of liver

ampulla of vater

S: small opening

F: spot where the pancreatic and bile ducts release their secretions into the intestines

L: enters into the first portion of the small intestine, known as the duodenum

Papilla of vater

S:

F: regulation of bile flow into the duodenum and the prevention of reflux into the bile and pancreatic duct system

L: duodenum