Microanatomy 3-2 Gi Glands

Front 1

How do salivary glands develop?

Back 1

out-pouchings of the oral epithelium migrate into the surrounding mesenchyme (much like early teeth-forming cells) and migrate to their final position.

Front 2

major salivary glands

Back 2

-parotid: just anterior to the ear, long duct in the cheek
-sublingual: alongside base of the tongue w/ many small ducts
-submandibular: inside angle of the mandible w/ medium length duct at front base of the tongue

Front 3

acini

Back 3

Secretory cells are located in blind-ended cul-de-sacs and secrete:
-Serous solution (water + proteins)
-Mucus secretion
-Mixed mucoserous solution

Front 4

Describe the journey of saliva from acinus to salivon.

Back 4

-acinus: cuboidal epith.
-intercalated duct

Front 5

parotid gland

Back 5

-mostly serous saliva
-basophilic acinar clusters
-significant adipose deposits

Front 6

submandibular gland

Back 6

-50/50 mixed serous & mucous

Front 7

serous demilune

Back 7

in slide preparation, serous glands get pushed out of the acinar ring to the outside of the mucous glands... in vivo they alternate side-by-side

Front 8

sublingual gland

Back 8

-mixed secretion, but mucous predominates

Front 9

α-amylase

Back 9

salivary enzyme which begins digestion of carbohydrates

Front 10

lysozyme

Back 10

salivary enzyme that kills bacteria

Front 11

sialolith

Back 11

protein and mineral crystalization which can build up in salivary glands and ducts

Front 12

Why does radiation treatment cause tooth decay?

Back 12

saliva has phosphate and calcium ions to help maintain mineralization of teeth; loss of salivary gland function following radtiation treatment results in severe tooth decay

Front 13

hemosiderin granules

Back 13

iron storage in the liver

Front 14

hepatic sinusoids

Back 14

channels formed by hepatocytes through which blood flows; sinusoidal capillaries formed by hepatocyte-endothelial cells

Front 15

Hepatocytes are stabilized by _____ fibers, which are smaller than type __ collagen and do not impede the flow of blood past the hepatocytes and other cells.

Back 15

reticular, type I

Front 16

Portal Triad (4 items)

Back 16

-portal vein: deoxy blood from gut tube
-hepatic artery: oxy blood from aorta
-bile duct: carries bile from liver
-lymphatic vessel: run alongside the other 3 but are not actually visible

Front 17

central vein

Back 17

blood from both the hepatic arteries (oxygenated) and the portal veins (deoxygenated) empty into the hepatic sinusoids and drain to a central vein. This blood will eventually reach the inferior vena cava.

Front 18

What is the composition of blood that comes from the portal vein?

Back 18

Roughly 75% of the blood comes from the portal vein and contains nutrients, erythrocyte breakdown products from the spleen, and other digested material. Because of this arrangement, hepatocytes rarely receive well-oxygenated blood.

Front 19

Describe the arrangement of the Classic Lobule.

Back 19

hexagon w/ central vein in the center & portal triads in the corners; highlights flow of blood

Front 20

Describe the arrangement of the Portal Triangle.

Back 20

portal triad in the center & central veins in the corners; highlights drainage of bile to ducts

Front 21

Describe the arrangement of the Liver Acinus.

Back 21

football shaped hexagon w/ two portal triads on the short axis and two cenral veins on the long axis; highlights hepatic metabolism and physiology

Front 22

For the liver acinus model, in which zone do hepatocytes receive the most oxygenated blood? What is the negative consequence?

Back 22

Zone 1 hepatocytes receive the most oxygenated blood because they are closet to the portal triad; consequently, they are the first to be damaged by toxins and/or bile duct occlusion.

Front 23

Which zone's hepatocytes are the first to die in ischemia or heart failure?

Back 23

Zone 3 hepatocytes are colest to the central veins, so they receive the least oxygenated blood and thus are the first to dies in ischemia or heart failure.

Front 24

Hemochromatosis

Back 24

Too much iron storage leading to damage of liver and other organs; can cause pain and be mistaken for fibromyalgia. 1/200 ppl of European descent. Tx: bloodletting

Front 25

perisinusoidal space (of Disse)

Back 25

Located between endothelial cells of capillaries and hepatocytes; filled by hepatocyte microvilli that absorb and release their goodies into the perisinusoidal space. Blood forms here in early life and can start again if needed.

Front 26

Stellate Sinusoidal Macrophages (Kupfer cells)

Back 26

-Location: alongside hepatic endothelial cells
-Fnx: phagocytose foreign material and damaged cells
-Other: following splenectomy, removal of damged erythrocytes

Front 27

Hepatic Stellate cells (Ito cells)

Back 27

-Deposit type I collagen in cirrhosis liver repair
-Store vitamin A

Front 28

How is bile produced in the liver kept separate from sinusoidal capillaries?

Back 28

Bile is kept w/in specialized canaliculi that sandwiched between hepatocytes

Front 29

Trace the path of bile from caniliculi to the duodenum:

Back 29

Bile caniliculi
(btw hepatocytes)
↓
Intrahepatic bile ductules
(collect multiple caniliculi)
↓
Interlobular bile ducts
(part of portal triad)
↓
Hepatic & common bile ducts
(large ducts)
↓
Hepatopancreatic ampulla
(pancreatic duct + common bile duct)
↓
Duodenum

Front 30

Cholangiocytes

Back 30

-Cuboidal/columnar cells that line the bile ducts in portal triads
-Microvilli on surface w/ one long sensory cilium that monitors bile flow rate

Front 31

How is bile flow regulated?

Back 31

Endocrine and autonomic nervous system can slow rate of flow, but it never actually stops.

Front 32

Gall bladder

Back 32

-Stores, concentrates and releases bile produced in the liver.
~90% of water is removed from bile by microvilli of simple columnar epith. cells lining the gall bladder
-Active transport of Na+, Cl- and HCO3- ions from the bile causes water to follow passively through specialized channels

Front 33

What causes gall bladder contraction and subsequent release of bile into the duodenum?

Back 33

Fat in the duodenum's lumen stimulates release of hormones to signal for contraction

Front 34

Gall bladder mucosa

Back 34

-Simple columnar epith w/ microvilli
-Lamina propria covered in fenestrated capillaries

Front 35

Gall blader muscularis mucosa & submucosa

Back 35

There is no muscularis mucosa or submucosa in the gall bladder.

Front 36

Gall bladder muscularis externa

Back 36

-Very large w/o distinct layering
-Surrounded by very thick layer of DICT
-Many vessels and nerves
-adventitia where in contact w/ liver
-Serosa on its free surface

Front 37

Rokitansky-Aschoff sinuses

Back 37

-Sinus of epithelium extending into and past the muscularis externa
-May be pathologic in and of themselves or serve as reservoirs for bactreria, predisposing to chronic infection and bile stone formation.

Front 38

Gallstones

Back 38

-cholesterol
-degraded Hb from spleen
-combination of the two

Front 39

Pancreatic capsule

Back 39

DICT septae that run into the gland; contains vessels and large ducts

Front 40

Exocrine pancreas

Back 40

Digestive hormones excreted into ducts and released into the duodenum; eosinophilic zymogen granules near the lumen:
-Proteolytic enzymes: cleave peptide bonds
-Amylolytic enzymes: cleave sugar polymers
-Lipases: cleave TGs to free FAs
-Nucleolytic enzymes: cleave nucleic acids to mononucleotides

Front 41

Pancreatic islets (of Langerhans)

Back 41

Synthesize endocrine hormones for metabolic regulation:
-A cells: (15-20%) Glucagon; islet periphery
-B cells: (70%) Insulin; islet centers
-D cells: (5-10%) Somatostatin; islet centers

Front 42

How is pancreatic secretion mediated?

Back 42

-Endocrine: Enteroendocrine hormones from the duodenum
-Exocrine: Parasympathetic stimulation

Front 43

Centroacinar cells

Back 43

-Flat squamous acinar cells at the base of intercalated ducts
-Add bicarb and water to pancreatic exocrine secretions which neutralize gastric acid and prevent premature activation of pancreatic enzymes

Front 44

How does the appearance of pancreatic duct cells change as they get further away from the acini?

Back 44

they become taller

Front 45

Pancreatitis

Back 45

Early activation of pancreatic proenzymes due to inflammation or other factors causing autolysis. One cause is gall stone obstruction of the hepatopancreatic ampulla.

Front 46

Follow the pathway exocrine pancreatic secretions follow from acinus to the duodenum.

Back 46

Intercalated Ducts
(within acini)
↓
Intralobar ducts
(collect secretions from acini in a pancreatic lobule)
↓
Interlobar Ducts
(collect secretions from multiple lobes)
↓
Main Pancreatic Duct
↓
Hepatopancreatic Ampulla
(main pancreatic duct + common bile duct)
↓
Duodenum