Digestive Glands

Question 1

what does the parenchyma of digestive glands derive from?

Answer 1

epithelium of the gut tube (endoderm)

Question 2

what are the 3 major salivary glands? what do they secrete?

Answer 2

parotid- all serous, submandibular- mostly serous, some mucous, sublingual- mostly mucous, some serous

Question 3

what is the structure of salivary glands?

Answer 3

branched acinar

Question 4

serous demilune

Answer 4

found in salivary glands with mixed sero-mucous

Question 5

what are the classifications of ducts draining salivary glands?

Answer 5

intralobular- within lobules and interlobular- between lobules

Question 6

what are the two types of intralobular ducts and what is their structure?

Answer 6

smaller- intercalated. simply squamous. closer to gland. intercalated ducts drain into striated ducts. striated ducts are larger and have cuboidal or columnar epithelium.

Question 7

why are striated ducts striated?

Answer 7

their basal membranes have extensive folding and mitochondria accumulate there creating the pattern

Question 8

what type of cell is responsible for the movement of gland secretion in parotid, submandibular and sublingual glands?

Answer 8

myoepthelium

Question 9

describe the structure of an interlobular duct

Answer 9

pseudostratified columnar or, in large ducts, stratified columnar

Question 10

how does the duct modify the secretion in salivary glands?

Answer 10

striated ducts reabsorb Na and Cl to create a hypo-osmotic solution. they also contribute IgA and lysozyme

Question 11

describe 3 ways in which the exocrine pancrease differs from the salivary glands

Answer 11

no striated ducts. no mucous secretion (only serous). retrograde extension of the intercalated ducts into the lumen of the acinar gland.

Question 12

what is the purpose of the retrograde extension of the intercalated ducts

Answer 12

they contribute large amounts of alkaline bicarbonate to the secretion. this will neutralize acidic gastric contents in the duodenum

Question 13

what are the 2 general types of secretions of the pancreas? how is each regulated?

Answer 13

enzymes- proenzymes- amylase, lipase, trypsinogen, etc. controlled by cholecystokinin. water and ions (bicarbonate)- controlled by secretin

Question 14

what are centroacinar cells?

Answer 14

the cells that have been extended backwards from the duct into the lumen of the pancreatic glands

Question 15

describe what happens to blood after it travels through the portal triad

Answer 15

portal triads (branches off bile duct, portal vein, and hepatic artery) are located peripherally. branches will flow inward from the periphery, mix together, and pass through sinusoids on their way to a central vein. hepatocytes have their basal membrane adjacent to the sinusoids, thus can exchange materials

Question 16

kupffer cells

Answer 16

resident liver macrophages found in the endothelium of sinusoids

Question 17

ito cells

Answer 17

vitamin a storage and local immunity, found in the per-sinuoidal space of disse (between the sinusoid and basal membrane

Question 18

describe the different sides of a hepatocyte

Answer 18

basal- faces sinusoid. apical- create walls of bile canaliculi. lateral- adjacent with other hepatocytes

Question 19

how does bile get secreted from hepatocytes

Answer 19

exocytosed out the apical membrane into bile canaliculi, which travel out into terminal ductules (canals of Hering) and ultimately into the portal triad

Question 20

describe the inner wall of the gallbladder

Answer 20

mucosa made of simple columnar epithelium, lamina propria, no muscularis mucosa. the wall is itself folded and the columnar epithelium have microvilli to increase surface area for concentrating bile

Question 21

describe the outer layer of the gallbladder

Answer 21

facing the peritoneum- lined by a visceral membrane. facing the liver, lined by a tunica adventitia

Question 22

how does the gallbladder concentrate bile?

Answer 22

it pumps Na and Cl out of the lumen, causing water to follow