digestive system part ii -nsu

8/14/2019 Digestive System Part II -NSU

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Histology 10b

Gregory Rodocker

NSU

Class Taken: Spring 2009



Organs associated with the Digestive tract

Three organs

Salivary glands

Liver

Gallbladder

Pancreas



Salivary Glands

There are three extra-oral cavity sets of

salivary glands

Parotid Submandibular

Sublingual



Salivary Glands

Serous cells in clusters that form circular structures called acini (sing. acinus)

Mucous cells are arranged along thetubules In the submandibular glands, the mucous

cells are along the tubules and the serous

cells cap the ends and are called serousdemilunes



Salivary Glands

Myoepithelial cells may function to contract

and push saliva along but thought to

function to maintain shape of duct system



Salivary Glands



Parotid Gland

A branched acinar

gland, mostly

serous cellsproducing lots of

enzymes



Salivary Glands

Parasympathetic control stimulates dilation

of the capillary blood supply leading to

copious watery secretion Sympathetic stimulation leads to

constriction of the capillaries leading to

small amounts of viscous saliva Dry mouth when nervous



Submandibular Gland

This gland

containing a

mixture of bothmucous and serous

cells



Sublingual Glands

This gland is largely

mucous producing

cells



Pancreas

A mixed exocrine and endocrine gland

producing enzymes and hormones

Exocrine cells are arranged in acini wholethe endocrine cells are in islets (islets of

Langerhans)



Pancreas



Pancreatic secretions

Trypsinogen 1, 2,and 3

Chymotrypsinogen Proelastases 1 and

2 Protease E Kallikreinogen Procarboxypepti-

dases A1, A2, B1

and B2

Amylase Lipases

Phospholipase Nucleases Majority produced

as inactive formsthat are activatedin the gut for theprotection of the

pancreas.



Pancreatic control

Nervous and hormonal stimulation lead to

pancreatic secretion

Secretin and cholecystokinin produced byEnteroendocrine Cells of the duodenum

Secretin – low enzyme, high

bicarbonate Cholecystokinin – high enzyme content

Parasympathetic stimulation



Liver

Second largest organ in body compared to

skin

Largest gland in the body Processes foodstuffs from digestion

Detoxifies and eliminates toxins



Liver lobule

Structural and functional unit of the liver is

the lobule

Strings of hepatocytes radiating from acentral vein that drains the lobule

At 3-6 locations around the lobule are

portal spaces that each contain a venule,an arteriole and a duct (and a lymphatic

vessel)



Specificity of hepatocytes by location in

the lobule

Blood flow in the lobule is from periphery to

center

As a result, the hepatocytes calledperilobular cells are exposed to a different

milieu than the centrolobular hepatocytes

Disease process and toxic damage maythus be sublobular rather than hololobular

in nature.



Neonatal Hyperbilirubinemia

Underdeveloped Smooth ER in hepatocytes



alcoholic hepatitis



Giant cell hepatitis



Cirrhosis



Gallbladder

Role is to store and

concentrate bile

between foodintake

Bile is concentrated

by pumping sodium

out with chloride

and water following



Gallbladder

digestive system part ii -nsu

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