12 Digestive Glands

8/2/2019 12 Digestive Glands

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The Digestive System


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Exocrine gland---with ductExocrine gland---with duct

Constituents of multicellular gland:Constituents of multicellular gland:

secretory portion:secretory portion: tubular,acinar or tubuloacinartubular,acinar or tubuloacinar

gland duct:gland duct: passage of secretionspassage of secretions

Endocrine gland---without duct


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Exocrine glandExocrine gland


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Salivary glandSalivary glandAcinus: mucous acinus, serous acinus ,mixed acinus

Duct: intercalated duct,striated duct,interlobular duct and

common duct

Serous acinus Mucous acinus

Cell type

Cytoplasm

ucleus

Secretions

Serous cell

Deep stained

Spherical,near the base

Protein

Mucous cell

Light-blue stained

spindle,near the base

Mucoprotein (mucus)


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Salivary glandSalivary gland


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Serous aciniSerous acini


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Mucous aciniMucous acini


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Mixed acini and semiluneMixed acini and semilune

Semilune: several serous

cells arranged like half-moon

in the mixed acinus


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Salivary glandsSalivary glands

1. components: parotid gland,submandibular1. components: parotid gland,submandibular

gland and sublingualgland and sublingual

gland,etc.gland,etc.

2. function: secreting saliva.2. function: secreting saliva.


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The characteristics of 3 pairs of salivary glandsThe characteristics of 3 pairs of salivary glands

Parotid gland Submandibular gland Sublingual gland

Acini

Ducts

Secretion

Pure serous gland

Long I.D.

25% saliva

More salivaryamylase,

less mucus

Mixed gland,

More serous acini

Short I.D.,

Long S.D.

70% saliva

Less salivaryamylase,

more mucus

Mixedgland,moremixed and

mucous acini

Without I.D.

5% saliva

Most mucus


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Parotid gland---pure serous glandParotid gland---pure serous gland


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Submandibular gland---mixed glandSubmandibular gland---mixed gland


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Sublingual gland---mixed glandSublingual gland---mixed gland


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PancreasPancreas

Parenchyma: exocrine portion: pancreatic secretions involved in

food-digestion.

endocrine portion(pancreas islet): secreting hormones


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1. Exocrine portion1. Exocrine portion

acini

ducts

Consists of serous cells surrounded

by basal lamina

Without myoepithelial cells,With several centro-acinar cells

in acinus cavity.

Long I.D. ,no S.D.


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Exocrine portion of pancreasExocrine portion of pancreas


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Exocrine portion of pancreasExocrine portion of pancreas


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2. Endocrine portion2. Endocrine portion

(pancreas islet)(pancreas islet)

A cell B cell D cell PP cell

Rate(%)

Distribution

Secretion

20%

Periphery

Glucagon--Increase bloodglucose levelsblood glucoselevels

70%

Center

Insulin--Decreaseblood glucoselevels

5% 5%

Somatostatin Pancreas

Inhibit the secretion polypeptide

of other cells


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Diabetes:Diabetes: absence or inadequate amounts ofabsence or inadequate amounts of

insulin.insulin.


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The largest digestive gland.The C.T.sends the septa into the parenchyma,

separating the hepatic lobules.

The portal area is present at the corner of the lobules.


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Classic hepatic lobuleClassic hepatic lobule

It is a structural unit of liver.Components

Hepatic plates: a single layer of hepatocytes arranged in radial.

Sinusoids:between hepatic plates and anastomosewith each other.

Central vein: occupies the centre of the liver lobule.


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hepatocytehepatocyte

3 functional surfaces:sinusoidal..,canalicular..,intercellular..

LM:

Profile:large,polyhedral in shape.

Cytoplasm:rich in Mitochondria,

Golgi complex, SER,RER,

lipid droplets, glycogen,etc.

Nucleus: large,central,lightly stained,

with obvious nuceulus.

EM: numerous microvilli protruding

into sinusoids and bile canaliculi.


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Function of hepatocyteFunction of hepatocyte

1.Bile secretion1.Bile secretion

2.Synthesis and storage2.Synthesis and storage

3.Detoxification and inactivation3.Detoxification and inactivation

4.Defence :related to Kuffer cell4.Defence :related to Kuffer cell

5.Hemopoiesis5.Hemopoiesis


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Bile canaliculusBile canaliculus

It is a small canal formed by opposed groovesIt is a small canal formed by opposed grooves

In the surface of adjacent hepatocytes.In the surface of adjacent hepatocytes.


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Bile canaliculiBile canaliculi


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Space of DisseSpace of Disse

ce between hepatocytesendothelium.

rovilli of hepatocytesrude into it, whichance the exchagesaterials.

ing fat cells :in spaceisse.responsible forstorage of Vit.A anduction of fibers.


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Portal areaPortal area portal canalsportal canals

portal triad:portal triad:

Interlobular arteries

Interlobular veins

Interlobular bile ducts

Hepatic artery

Portal vein

Common bile duct


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Hepatic circulationHepatic circulation

Common bile duct

Portal vein

Hepatic artery

Hepatic vein

Interlobular bileducts

Interlobular vein

Interlobular artery

vein

Bile canaliculi

sinusoids

Central vein

Hepatic hilum Hepatic lobulePortal area


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Key pointsKey points

1. The structure and function of pancreas.1. The structure and function of pancreas.

(exocrine portion and endocrine portion),the(exocrine portion and endocrine portion),the

cellular components of pancreas islet andcellular components of pancreas islet andtheir function.their function.

2.The definition of hepatic lobule and portal2.The definition of hepatic lobule and portalarea.sinusoid ,space of Disse,Kuffer cell;area.sinusoid ,space of Disse,Kuffer cell;

3.The formation of bile canaliculi.3.The formation of bile canaliculi.

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12 Digestive Glands