Histo 3 Flashcards by Tiffany Reid

What type of gland is the pancreas?

Endocrine and exocrine

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The exocrine pancreas is a ___ gland

Serous

*produces:
Digestive enzymes such as amylase and lipase
Proenzymes such as trypsinogen

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Secretory acini of the pancreas are composed of what type of cells?

Pancreatic acinar cells

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Typical characteristics of a protein secreting cell

Central nucleus
Euchromatic nucleus
Basally placed RER
Apical secretory granules
Broad base, narrow apex

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Intralobular ducts of the pancreas begin ___

From within the acinus

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Interlobular ducts drain ___

Directly into the main pancreatic duct which drains into the hepatopancreatic ampulla of the duodenum

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Ductal cells found within the secretory acini of intralobular ducts in the pancreas.
Shape?
Stain?

Centroacinar cells
Squamous
Stain lighter than pancreatic acinar cells
Continuous with intercalated duct cells

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Intercalated duct is a short portion of intralobular ducts of the pancreas lined with ___ epithelium

Low simple cuboidal

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Intercalated duct cells of the pancreas add ___ and ___ to the exocrine secretion. They drain into ___, which are lined with ___ epithelium.

Bicarbonate
Water

-Intralobular collecting ducts
Simple cuboidal or low simple columnar

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True or false: there are no striated ducts in the pancreas

True

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The main pancreatic duct is lined with ___ epithelium

Simple columnar

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Regulation of exocrine pancreas secretion is under ___ control

Hormonal and neural

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Hormones that stimulate the secretion of enzymes and proenzymes by the exocrine pancreas?
What are they secreted by?

CCK (cholecystokinin)
Secretin
-enteroendocrine cells of the duodenum

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Sympathetic/Parasympathetic innervation of pancreas

S: blood flow
P: acinar and centroacinar cells

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Islets of Langerhans make up ___% of the pancreas but are more numerous in the ___

Tail

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Cell types found within Islets of Langerhans

A cells
B cells
D cells

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Secrete glucagon
20% of all islet cells
Mostly at the periphery

A cells or Alpha cells

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Secrete insulin
70% of all islet cells
Mostly at the center

B cells or Beta cells

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Secrete somatostatin

5% of all islet cells

D cells or Delta cells

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Actions of glucagon/insulin/somatostatin?

Glucagon ⬆️ blood glucose
Insulin ⬇️ blood glucose
Somatostatin inhibits release of insulin and glucagon

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What is the largest gland in the body and also the largest internal organ?
Endocrine or exocrine?

Liver

Exocrine and endocrine

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Endocrine part of the pancreas is made up of __

Islets of Langerhans

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Origin of the liver

From an evagination of the foregut (part that becomes duodenum) so it is endodermal in origin

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6 functions of the liver

Bile production
Synthesis of plasma proteins
Lipid metabolism
Glucose metabolism
Storage and conversion of vitamins and iron
Detox

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Main components of bile

Water Bile salts Bilirubin Electrolytes

Serves as a solute for other components of bile

Water

Acts as a detergent that emulsifies the fat in the intestine to digest and absorb it

Bile salts

End product of hemoglobin degradation (occurs in the spleen) which is broken down by the liver into glucuronide and excreted into the intestine to carry it out for disposal

Bilirubin

Establish and maintain bile as an isotonic fluid. Reabsorbed in the gut

Electrolytes - Na, K, Ca, etc.

Production of bile is an (endocrine/exocrine) function of the liver

Exocrine

The liver stores glucose in the form of ___

Glycogen

Vitamin roles of liver

A: Store, maintainence, and uptake D: converting to circulating form (NO STORAGE) K: transported to liver from small intestine by chylomicra, absorbed, partially used, then secreted with VLDL into blood

Parenchyma of the liver consists of organized plates of ____. Normally ____ thick and separated by ____, these plates form ___

Heoatocytes One cell Sinusoidal capillaries Hepatic lobules

Stroma: Connective tissue capsule that surrounds the liver

Glisson's capsule | Thicker at the hilum, where blood vessels enter and exit

Blood supply to the liver

1. Portal v. - nutrient rich, oxygen poor blood from spleen, pancreas, and alimentary canal 2. Hepatic a. - oxygenated blood from the celiac trunk

Outflow of blood from liver

Hepatic lobules -- hepatic v. --- IVC

True or false: hepatic veins follow the branching patterns of the hepatic arteries

False

Large, discontinuous capillaries with fenestrated endothelial cells. Separate plates of hepatocytes

Hepatic sinusoids

Blood from hepatic sinusoids drains into the ___, which is located ___ and drains into ___, which then drains into ___

Central v. In the center of a classical hepatic lobule. Sublobular veins Collecting tributaries of hepatic veins

Central veins have ____ CT associated with its wall, sublobular veins have ___

Very little | More

3 types of liver cells

``` Hepatocytes (main type) Kupffer cells Ito cell (fat storing) ```

Average life span of hepatocytes

3 months

Hepatocytes nucleus

Large and spherical - Often binucleated, majority are tetraploid - euchromatic - one or two nucleoli

Main types of organelles that are abundant in hepatocytes

- Mitochondria - RER-synthesis of fibrinogen, prothrombin, blood albumins - SER-detox, lipid synthesis - peroxisomes - Lysosomes

Kupffer cells are part of the ___ system, are derived from ___, and reside within the ___

Mononuclear phagocytic Blood monocytes Hepatic sinusoids

Ito cells (fat storing cells) are found __, their main function is ___, and they are derived from ____

In the space of Disse Vitamin A storage Fibroblasts

In pathological conditions, ___ proliferate and start synthesizing collagen, causing liver fibrosis

Fat-storing cells (Ito cells)

Macro vs micronodular cirrhosis

Hepatitis vs. alcoholism

Gap between hepatocytes and endothelial cells

Space of Disse

Portal canals are located __

At the angles of the hexagonal prisms

Classic hepatic lobule

Hexagonal prism with central v. | Plates of hepatocytes radiate from the center towards the periphery separated by hepatic sinusoids

___ bring blood to the lobules of the liver and collect bile from the lobules. They contain the portal triad and loose CT. They have 3 main components;

Portal canals 1. Interlobular branch of portal v. 2. Interlobular branch of hepatic a. 3. Interlobular bile duct

The interlobular bile duct is lined with ____ epithelium

Simple cuboidal

Blood from the ____ is conducted to the ___ through the terminal branches of the hepatic a. and the portal v.

Interlobular branches of the hepatic a. and the portal v. | conducted to the hepatic sinusoids

Hepatic sinusoids are equivalent to ___ but are different how?

Capillaries in CT | Larger and more irregularly shaped

The blood in the hepatic sinusoids flows from the ____ toward the ____

Periphery of the lobule toward the central v.

Bile in the bile canaliculi flows from the ___ towards the ___

Center | Periphery

Space of Disse is also called ___. It is the site of exchange of material between ___

Perisinusoidal space | Blood and liver cells

Concepts of liver lobules

Classical Portal lobule Liver acinus

Portal lobule concept

Emphasizes exocrine function and production of bile - centered on portal triad - duct is in the center - outer margins are imaginary lines drawn between the 3 closes central veins

Liver acinus concept

Centered on terminal branches of portal v./hepatic a. and on canals of Hering - rhomboid shape - emphasizes the different oxygen and nutrient content of blood in the lobule - 3 zones

Liver acinus | Zone 1

Closest to interlobular blood vessels that bring blood to the liver acinus - these cells receive oxygen first - last to die of circulation is impaired - first to regenerate - first to show morphological changes and cell death during bile stasis and intoxication

Liver acinus | Zone 2

Middle zone | Oxygen, nutrient, and toxin levels are midway between zones 1 and 3

Liver acinus | Zone 3

Die first in situations of reduced perfusion | Last to respond to toxins and bile stasis

System of conduits of increasing diameter that bile flows through from the hepatocytes to the gall bladder

Biliary tree

The smallest branch of the biliary tree, which begins from the plates of hepatocytes Arrangement?

Bile canaliculus Chicken wire Form a loop around the 4 sides of the hepatocytes

Bile canaliculi drain into ___, which then drain into ___ and these then drain into ___

Bile ductules (canals of Hering) Interlobular bile ducts Common hepatic duct

Locations of bile ductules and interlobular bile ducts

1. Classic lobule | 2. Portal triad

Pear shaped distensible sac attached to the visceral surface of the liver

Gall bladder

The lumen of the gall bladder mucosa is lined with ___ epithelium

Simple columnar

Muscularis mucosae of gall bladder

Not present

Muscularis externa of gall bladder is formed by ___

Bundles of smooth muscle and collagen

The part of the gall bladder projecting into the peritoneum is surrounded by ___, the rest has ___ that blends into surrounding CT

Serosa | Adventitia