3. Histology Flashcards by J L

• Only two segments of the GI tract that contain submucosal glands > ____ (lower 1/3), or the ____ of the SI
○ Nowhere else you will find submucosal glands

esophagus

duodenum

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General Organization of the GI Tract

Mucosa:
Three components:
Lining: ____. May show specialized structures.
Lamina propria: Loose ____tissue.
Muscularis mucosae: ____ muscle.
Other structures:
Lymphatic nodules:
____.
____ intestines.
Secretory glands:
Mucosal: extending into the ____.
Submucosal: extending into the ____.• Mucosa made up of three componentsn:
○ Epithelium
§ May or may not show specialized structures
○ LP
§ Not always present in every organ
○ Muscularis
§ May or may not be there in all the sections
• Embedded in the mcuosa and dpeneidng on which section of tract: may find LM or SG

epithelium
connective
smooth
lamina propria
small and large
lamina propria
submucosa

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General Organization of the GI Tract

Submucosa:
Dense ____ connective tissue.
Large blood vessels, lymphatics and nerves branching into mucosa and submucosa.
Glands only in ____ and ____.
Muscularis:
Smooth muscle:
Inner layer: ____.
Outer layer: ____.
Skeletal muscle:
Only in ____ and anal sphincter.
Adventitia:
Connective tissue.
May be covered by a ____(simple squamous epithelium) + thin CT layer forming a ____ (serous membrane).

irregular
esophagus
duodenum

circular
longitudinal
upper esophagus

mesothelium
serosa

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The Esophagus

• Functions:
• Propels swallowed food from oral cavity to
stomach.

• Layers:

Mucosa: ____ folds.
Epithelium: ____ squamous.
Lamina propria: CT.
____glands.
Muscularis mucosae:
ONLY present near the ____.
Submucosa: CT.
Submucosal glands: ____ (mucins) and ____ (lysozyme).

• Muscularis:
• Two layers: \_\_\_\_ and
longitudinal.
• Upper third: \_\_\_\_ muscle.
• Middle third: \_\_\_\_ muscles.
• Lower third: \_\_\_\_ muscle.

longitudinal
stratified non-keratinizing
cardiac esophageal
stomach

mucous
serous
circular
striated (skeletal)
striated and smooth
smooth

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• Mucosa is SSE that is non-keratinized
		○ From \_\_\_\_ to \_\_\_\_ (stomach)
		○ Constant
	• At LP
		○ In cardial region (lower segment around the stomach, above the LES), the only place you find the cardiac esophageal glands
			§ More abundant in this are
			§ One half down
	• Submucosa
		○ Distinct structure: in the lower 1/3
			§ Unusual in the GI tract
			§ Produce mucins
				□ Mucus that covers and protects esophagus and stomach
				□ Lysozyme - \_\_\_\_
	• Muscularis
		○ Depending on where we're looking - will be composed of skeletal or smooth muscle
			§ Inner: circular
			§ Outer: longitudinal
			§ Upper 1/3: skeletal
			§ Middle 1/3: skeletal and smooth
			§ Lower: 1/3 smooth
		○ Tells you how the esophagus works
			§ Upper part - innervated by \_\_\_\_ fibers
				□ This area is still controlled during \_\_\_\_
			§ Once food into the esophagus - the movement that pushes it down > \_\_\_\_ - through the creation of peristaltic movmements - autonomic innervation of smooth muscle

upper sphincter
lower sphincter
antibacterials
voluntary
swallowing
involuntary

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The esophagus

• Longitudinal folds
	○ \_\_\_\_ and \_\_\_\_ are invaginated
• At mucosa - can see the SSE lining the lumen
• Can see secretory glands in the submucosa
	○ Lower \_\_\_\_ of the esophagus

mucosa
submucosa
third

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The esophagus

• \_\_\_\_ separates the submucosa and the mucosa
	○ Denotes that it's closer to to the \_\_\_\_
• Reason for the SSE - the esophagus is in contact with rough material
	○ Continuously regenerating layers of new cells - protects the underlying mucosa

muscularis mucosae

stomach

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GEJ

Mucosa of esophagus vs. stomach
• Upper: ____ - correpsondign to the esophagus
• Down: secretory epithelium with ____ and glands that’s part of the stomac
○ Highly secretory

SSE

gastric pits

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The Stomach

• Functions:
• Homogenization and chemical processing of
the swallowed semisolid food.
• Four regions:
1. ____: surrounds the esophageal opening.
2. ____: to the left of the esophageal opening.
3. ____: central region.
4. ____: extending to the gastroduodenal orifice.

cardia
fundus
body
antrum

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The Stomach

• Epithelium: ____ epithelium.
• Lamina propria:
• Loose CT.
• Surrounds the cardiac, gastric, and pyloric ____.
• Muscularis mucosae: ____ fibers, some project into the ____ to induce
gland secretions.

Submucosa:
Dense ____ CT.
____
Submucosal plexus of ____.
Muscularis:
Three layers of smooth muscle: ____, ____, and ____.
____ plexus of Auerbach.

The Stomach
• The epithelium is secretory
• The muscualrisu is made up of smooth muscle fibers
○ Three layers: you now have an oblique layer
§ Where you find the myenteric plexus of auerbach

secretory columnar simple
glands
smooth muscles
mucosa

irregular
lymphatics
meissner

circular
oblique
transverse
myenteric

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The Stomach: Gastric Mucosa

• L: SEM showing wall of stomach
	○ Rugae
		§ Find what you see on the right side
		§ Invaginations of the \_\_\_\_ and \_\_\_\_ of the wall of the stomach
			□ \_\_\_\_ contains the gastric glands
				® Pits are tops of conduits that reach the sruface of the stomach
		§ Thick mucosa - due to the environement
		§ Highly secretory
			□ Produce \_\_\_\_ and \_\_\_\_ and \_\_\_\_

mucosa
submucosa
mucus
HCl
pepsinogen

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The Cardia Region of the Stomach
• Secretory mucosa
○ Find gastric glands that are____ and form a ____ tube that ends in the pit at the surface of the soamtch
○ The glands are highly ____ (extend the longitude of the galnd itself without penetrating thorugh the muscularis mucosae)
§ Look at these glands in LM picture > box area > coiled ends produce copmlex morphology where you cannot follow a gland from the pit to the ____
□ Explains why most mucosa is occupied by the coils formed by the ____
□ Gastric glands are formed by secretory cells that produce ____
® Not different from those found outside the gland on the epithleium of the ____ at this elevel
® Produce mostly ____

simple
single
coiled
conduit
gastric glands
mucus
stomach
mucus

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Fundus-Body Region of the Stomach: Gastric Glands

Very abundant: 15 million.
Gastric gland regions:
____
____
____• Main region In terms of secretory function > ____ region combined
• A large number of gastric glands
○ Are different from those in the ____region
○ Tubular glands
§ Combined into ____+ tubes that end at surfcae of stomach at a single pit/faveola
§ Most complex gastric glands
§ The glands are divided into:
□ Pit
□ Neck
□ Body
® Different ____ are found in each region

pit
neck
body
fundus/body
cardia
two
cells

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Fundus-Body Region of the Stomach: Gastric Glands
• Very abundant: 15 million.
• Gastric gland regions:
• Pit: surface ____cells.
• Neck: ____ cells, stem cells, and ____ cells.
• Body: ____ cells, chief cells, ____ cells.

	• Pit
		○ Gland connects with surface of \_\_\_\_
		○ Surface mucous cells
			§ Same cells found outside of the gland lining the epithelium of the body of the stomach
	• Neck
		○ Richer population is located
		○ Mucous neck cells
			§ Different from surface cells
	• Body
		○ Depending on the region will find different cell populations

mucous
mucous neck
parietal
parietal
enteroendocrine
stomach

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Fundus-Body Region of the Stomach: Gastric Glands

• At \_\_\_\_ of the gland near the surface of the stomach
	○ Secretory cells that are similar to \_\_\_\_ (morphologically slightly different)
		§ These cells are secretory for \_\_\_\_
		§ Involved in \_\_\_\_ in the wall of the stomach
			□ From the HCl that is produced in deeper regions of the gastric gland

pit
goblet cells
mucus
protection

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Fundus-Body Region of the Stomach: Gastric Glands

• Reach neck of the gland
	○ Mucous neckc ells
		§ Different from the ones found at the \_\_\_\_
		§ Don't just recognize the morphology
		§ In the neck, find cells that produce \_\_\_\_ anda re \_\_\_\_

pit
mucus
secretory

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Fundus-Body Region of the Stomach: Gastric Glands

• Upper and lower regions of the body of the gland is where it's interesting
• Start to find specialized populations fo cells
	○ Parietal cell
		§ Produce \_\_\_\_l
		§ \_\_\_\_
		§ \_\_\_\_ stain
		§ \_\_\_\_ nucleus
		§ Remember where they're located and what they do

HCl
secretory
pale
central

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Fundus-Body Region of the Stomach: Gastric Glands

• Body of the gastric gland
	○ In the lower region: chief cells
		§ \_\_\_\_ staining (nuclei are basal)
		§ \_\_\_\_ stain in the apical domain > produce \_\_\_\_
			□ Deep red stain is bc of the secretory granules that stain well
			□ Less pale than the parietal cells
	○ Will also find \_\_\_\_ cells (D cells)
		§ Respond to the presence of \_\_\_\_s in the chyme (digestive mix) and respond to the \_\_\_\_ produced by the secretion of HCl
		§ Release hormones into the BS > regulate the secretion of these same glands
			□ Hormone = gastrin

basophilic
dark
pepsinogen
enteroendocrine
proteins
HCl

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Fundus-Body Region of the Stomach: Gastric Glands

• Exocrine glands - major of the stomach
• Parietal cell
	○ Produces HCl
	○ Produce \_\_\_\_
		§ Required for absorption of vitamin B12 and internalize them
		§ Binds to B12
• Chief cells
	○ Produce pepsinogen
		§ Inactive - \_\_\_\_ form of the enzyme, pepsin (a protease)
		§ Starts the degradation of proteins at level of the stomach
• Compare the morphology
	○ Parietal
		§ \_\_\_\_ cells
		§ Cytoplasm is firstly \_\_\_\_, and out of the invagination > some cytoplasmic processes > smaller degree of invaginations are prodcued > \_\_\_\_
			□ By increasing the secretory surface of the cell > ensure high rate of \_\_\_\_ secretion and production
			□ To increase the secretory surface
		§ Rich in \_\_\_\_
			□ Require a lot of energy to pump Cl and protons to form HCl
				® A lot of ion trafficking bt the interstitium and basal domain of the cell
				® Also pumping at the level of the canaliculi
	○ Chief cells
		§ Very different morphology!
		§ Nucleus pushed to \_\_\_\_ domain
		§ Apical domain is characterized by presence of secreotyr garnules
			□ Zymogen - pepsinogen
			□ Stained very \_\_\_\_

IF
zymogen
pale
invaginated
secretory canaliculi
HCl
mitochondria
basal
darkly

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Pyloric Region of the Stomach

• Also find \_\_\_\_ glands
	○ Complex glands: \_\_\_\_+ branches of secretory tubules that converts into a s ginle secretory duct > ends in a single \_\_\_\_
• Pyloric glands
	○ Lined by secretory cells that produce mucus
	○ No parietal, chief or NE cells
• Thick mucosa
• Deep pit lined by secretory cells that produce mucus
• Structure of gland is different
	○ Much \_\_\_\_ into the tissue
	○ Down to where the \_\_\_\_ are joined

secretory
three
pit
deeper
secretory glands

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the small intestine

• Functions:
• Continuation in the duodenum the
\_\_\_\_ process initiated in the stomach.
• Absorbed foods digested by enzymes
produced in the intestinal mucosa and
pancreas. 
• Segments:
• \_\_\_\_. 
• \_\_\_\_.
• \_\_\_\_.

digestive
duodenum
jejenum
ileun

Folding of the Small Intestine Wall
• Increases absorption surface.
• Four degrees of folding:
1. \_\_\_\_.
2. \_\_\_\_.
3. \_\_\_\_
4. \_\_\_\_.

• Emphasize the folding of the SI wall increases dramatically the surface of the organ due to their absorptive function
	○ For a given length of tube > fold the tube through 4 degrees > increase the SA dramatically
	○ First degree - formation of plica circularis
		§ Invaginations of the \_\_\_\_ and \_\_\_\_
	○ Second degree - formation of villi
	○ Third degree - inside each villi - formation of glands
		§ Invaginations of the \_\_\_\_
	○ Each cell lining he epithelium of the SI > has their apical domain of \_\_\_\_ also folded > microvilli

plicae circulares
intestinal villi
intestinal glands
enterocyte microvilli
mucosa
submucosa
mucosa
cytoplasms

Folding of the small intestine wall

• 1st degree of folding: Plicae circulares (sing. plica circularis):
• Evagination of the ____ and part of ____.
• NOT present in ____ duodenum.
• Prominent in ____.
• Disappear halfway
down the ____.

* Not dramatic invagination of mucosa and submucosa
* See this > you're in the jejunum

mucosa
submucosa
upper
jejunum
ileum

Folding of the Small Intestine Wall: Villi

2nd degree of folding: Villi (sing. villus):
Evagination of the ____ ONLY.
Entire surface of the ____.

mucosa

small intestine

Folding of the Small Intestine Wall: Villi ``` • R: CS of a single villus ○ See intestinal epi ○ Most cells are ____ § Intestinal absorptive cells § Pale, few that are embedded in the epithelium are ____ □ Produce mucus ○ Inside of the villi you find ____ § Both arterial, veins and the lymphatics (____; where everything absorbed by the enterocyte is transferred to the liver) ```

enterocytes goblet cells capillaries lacteals

Folding of the Small Intestine Wall: Crypts of Lieberkühn and Microvilli * 3rd degree of folding: Glands or crypts of Lieberkühn. * Invagination of the ____: open between villi. * Extend to the ____. * Contain ____ glands. • 4th degree of folding: Microvilli (sing. microvillus). • Evagination of the ____ domain of the enterocyte (intestinal epithelial cell).

mucosa muscularis mucosae tubular apical

Folding of the Small Intestine Wall: Crypts of Lieberkühn * 3rd degree of folding: Glands or crypts of Lieberkühn. * Invagination of the mucosa: open between villi. * Extend to the muscularis mucosae. * Contain tubular glands. • Villis are extensions of the mucosa into the lumen • Crypts are pits that come down from surface of mucosa down to the ____ • If didn't have this > the wall of the intestine would only have the ____ • To increase the surface more, and locate the glands in the SI > why the ____ are designed • R: CS of villi and several crypts ○ The actual level of the intestinal wall is in the ____ portion ○ Bottom of crypt almost reaches the muscularis mucosa

muscularis mucosae villi crypts of liebrkuhn

Folding of the Small Intestine Wall: Crypts of Lieberkühn • 3rd degree of folding: Glands or crypts of Lieberkühn. • Invagination of the mucosa: open between villi. • Extend to the muscularis mucosae. • Contain tubular glands: • ____ cells: secretory, mucus. • ____ cells: innate immunity. • ____ (APUD) cells: >40 types. • Tubular glands not different from gastric glands in terms of structure, but different in secretions ○ Secretory epithelium > columnar epithleium § With goblet cells ○ Minor cell populations § Paneth cells □ Located at bottom of crypt § Enteroendocrine cells □ Distributed throughout the tissue □ 40 different types > create unique hormones; regulate ____ form intestine, BA formation in the liver, and contraction of the ____

``` goblet paneth enteroendocrine secretions stomach ```

Folding of the Small Intestine Wall: Crypts and Microvilli * 4th degree of folding: Microvilli (sing. microvillus). * Evagination of the ____ of the enterocyte (small intestine epithelial cell). * Cytoplasmic processes of the enterocytes are evaginated * A lot of microvilli are located on each enterocyte

apical domain

SI muscularis and serosa * Muscularis: responsible for ____ and ____ movements. * Inner ____ smooth muscle. * Outer ____ smooth muscle. * Adventitia or Serosa: * Thin connective tissue. * Covered by ____: ____ (mesothelium)

``` segmentation peristaltic circular longitudinal periotoneum SSE ```

``` Small Intestine Epithelium • ____ epithelium. • Four major cell types: • ____: absorptive cells. • ____ cells: mucus-secreting. • ____ cells: innate immunity. • ____cells: • S cells: ____ • I cells: ____. ```

``` simple columnar enterocytes goblet paneth enteroendocrine secretin cholecystokinin ```

Small Intestine Epithelium: The Enterocyte • ____. • Apical domain with ____ with microvilli (≈ 3000). • ____-associated digestive enzymes: lactase, maltase, sucrose. • Complex structure of microvilli • Maintained in shape by having a core of ____ filaments (not just extension of cytoplasm) ○ Mostly formed by actin polymers that are anchored to int filaments also ○ Maintain integrity of microvilli • Apical domain > brush border

absorptive microvilli membrane actin

Small Intestine Epithelium: Paneth Cells ``` • Paneth cell ○ Stain ____ ○ Bottom at ____ ○ Involved in ____ immunity § Not mediated by ____ § Oldest types of immunity § Produce two types of substances: □ ____ □ ____ ® Both are antibacterial agents □ Can produce ____ ® Mediating inflammation in response to infectious diseases/tissue injury ```

``` darkly crypt innate antibodies lysozyme defensins TNFalpha ```

Histological Differences of the Small Intestine Segments: Duodenum ``` 1. Brunner’s glands: • ____ mucus: mucins, HCO3-. • ____l. 2. Villi ____ and broad: ____-like. 3. Base of the crypts of Lieberkühn may contain ____ cells. ``` Duodenum • Villi ○ Not long, and characterized by leaf-like shape • Brunner's glands ○ Located in submucosa ○ Only submucosal glands in the ____ ○ Below the villi - find secretory glands > brunner's glands > duodenum ○ Produce alkaline mucus ○ Two types of secretory cells: § Produce mucus (mucins) § Cells that produce bicarbonate □ Neutralize the acid coming from the stomach ○ Drain in the CoL; and the mucus reaches lumen of intestine • At base of crypt ○ Paneth cells

``` alkaline submucosal short leaf paneth SI ```

Histological Differences of the Small Intestine Segments: Jejunum 1. No Brunner’s glands in the ____. 2. Villi ____ and ____-like. 3. ____ cells at the base of the crypts of Lieberkühn. 4. ____ may be present but not predominant.

``` submucosa long finger paneth peyer's patches ```

Histological Differences of the Small Intestine Segments: Ileum 1. Diagnostic feature: ____ 2. No Brunner’s glands in the ____. 3. Villi ____ but ____-like. 4. ____ cells at the base of the crypts of Lieberkühn. ``` Ileum • Presence of peyer's patches ○ Big masses of ____ tissue ○ Part of the immune system ○ Specialized pop of cells > ____ > grab antigens and transport toward lymphoid part of nodule > immune response ○ Located in the ____ • Short villi (to both) • Bottom of crypt > paneth cells ```

``` peyer's patches submucosa short finger paneth lymphoid M cells mucosa ```

4. the LI ``` • Functions: • Absorption of ____, Na+, vitamins. • Secretion of ____ mucus. • Defecation. • Segments: 1. ____. 2. Ascending, transverse, and descending colon. 3. ____. 4. ____. ```

``` water alkaline cecum rectum anus ```

LI ``` • NO ____. • Mucosa: • Epithelia with ____*: • Surface ____ epithelium. • ____epithelium. • Lamina propria and muscularis mucosae with abundant ____ nodules. ``` * Submucosa: CT. * Muscularis with ____. * Serosa with ____. * = IMPORTANT: Do NOT confuse the tubular glands of Lieberkühn in the LI with the glands or crypts of Lieberkühn in the SI. ``` • Some degree of folding, but no villi • Glands are ____ than the crypts ○ Formed by SCE ○ Glandular - produce mucus in high levels ○ Glands have high numbers of ____ § Goblet cells are more pale in staining than the enterocytes • Thick mucosa • Lymphoid nodules - not ____ ○ Abundant ```

``` villi tubular glands of lieberkuhn simple columnar glandular lymphoid taeniae coli appendices epiploicae ``` simpler goblet cells peyer's patches

LI GLANDS 1. Lined by ____ enterocytes and goblet cells. 2. Apical domain of enterocytes with microvilli: ____ than in small intestine. 3. Scattered ____ cells. 4. NO ____ cells. ``` • Goblet cells ○ Palest staining • Some enterocytes ○ Apical domain - microvilli § Shorter § Look at LI - may appear like they don’t have brush border but THEY DO (much smaller than the SI) • Some neuroendocrine cells (minor) ```

columnar shorter neuroendocrine paneth

LI: the appendix * Diverticulum of the ____. * Layer organization like ____. * Mucosal ____ but not villi. * Diagnostic: * ____ nodules infiltrating the lamina propria. * Extend into ____ and submucosa. ``` • Presence of lymphatic nodules • Mucosa is highly folded ○ Lumen is very ____ • Finding tubular glands of leiberkuhn • Lymphocytes can infiltrate in the LP ○ Surrounding the ____ ○ Appendix act as refuge for bacterial species • Why isn't immune system reacting? ○ All lymphos that are normally in contact that they recognize as ____, so they don't attack ```

``` cecum large intestine folds lymphoid mucosa narrow secretory glands friends ```

Rectum, Anal Canal and Anus ``` • Rectum: • ____ portion of GI tract. • Thick mucosa with ____ epithelium. • ____ with goblet cells. • 8-10 mucosal anal columns, with anal mucous glands. ``` * Anal canal: * ____ epithelium. * Anus: * Sphincters: * Internal: ____ muscle. * External: ____ muscle. * ____ epithelium. • Transition at level of mucosa from rectum to the anal canal and the anus ○ Reverse of esophagus to stomach • Below pectinate: ____ SE • Anal canal ○ Transition from secretory mucosa with tubular glandsa nd lymphoid nodules ○ Below pectinate: statified, non-keratinized > not secretory anymore

terminal simple columnar crypts of lieberkuhn stratified low/non-keratinizing squamous smooth skeleta stratified keratinizing squamous non-keratinized stratified

• Transitions abruptly into the ____

SSE

``` Digestive Glands • Functions: • ____. • ____ • ____ ``` * Major digestive glands: * ____ glands. * ____. * ____.

lubrication protection absorptive salivary pancreas liver

Pancreas * Dual-function organ: * Exocrine: * Synthesis and secretion of digestive enzymes via a system of ____. * Endocrine: * Synthesis and secretion of hormones into the ____ that regulate glucose, lipid, and protein metabolism. * ____% of pancreatic mass. • Products of exocrine of pancareas are important ○ Produces digestive enzymes required for digestion of macromolecules • Also has an endocrine function ○ Insulin and ____ produced here

ducts BS 2 glucagon

``` Pancreas • Histology: • Surrounded by CT, but NOT ____ • Divided into ____ separated by CT septa containing vessels, lymphatics, nerves, and secretory ducts. • Exocrine functional unit: ____. • Endocrine functional unit: ____. ``` • Thymus, lymph nodules, spleen > all surrounded by CT capsule ○ Spleen had contracting capsule w/ smooth muscle • CT divides organ into lobules due to the septa (extends into the parenchyma that causes the separation) ○ Similar to ____, lymphoid organs • Acinus ○ Just like ____ - very similar!

capsule lobules acinus islet of langerhans spleen salivary glands

Pancreas ``` • Dense organ divided into clusters ○ Acini § ____ component ○ IoL § More palely stained § ____ component ○ In middle is a septa that separates the lobules ○ Organ is highly vascularized ```

exocrine | endocrine

Exocrine Pancreas • Functional unit: acinus. • ____ secretory gland: very similar to salivary glands. ``` • Acinar cells: • 5-8 ____ cells, with basal lamina. • ____ nucleus. • Apical____ with digestive enzymes. ``` ``` • Centroacinar cells: • Line the ____ of the acinus. • Secrete ____. • Unique to ____ (NOT present in salivary glands). ``` • Difference bt this ands alivary glands ○ Presence of centroacinar cells § Continuation of ____ that go into the center of the acinus § Unique to the pancrease • Acinar cells produce enzymes • Centroacinar cells ○ Produce bicarbonate (difference from salivary) ○ Neutralizes the acid coming from the stomach at the level of the duodenum (where the secretions end up, via the papilla of vader)

compound pyramidal basal zymogenic granules lumen HCO3- pancrease secretory duct

Exocrine Pancrease: Ducts * Intercalated ducts: * ____ epithelium. * Continuation of the ____ cells into the CT stroma. * Excretory (interlobular) ducts: * ____ epithelium. • Downstream of eacha cini > secretory ducts > interalated ducts > excretory duct ○ Intercalated ducts are more cuboidal that transitions into columnar epithelium

simple cuboidal centroacinar simple columnar

Exocrine Pancreas • Centroacinar cell surrounded by secretatory acinar cells • Islet of langerhans • Intercalated duct ○ ____ epithelium • Inside each acinar cells > ____ of zymogen ○ Filled with digestive enzymes ○ Secreted as ____ zymogens

cuboidal granules inactive

Endocrine Pancreas: Islets of Langerhans • Islet surrounded by ____ pancreas

exocrine

Endocrine Pancreas: Islets of Langerhans * Richly ____ masses scattered throughout the pancreas. * Separated from exocrine pancreas by ____.

vascularized | CT

Endocrine Pancreas: Islets of Langerhans * Cell types: * Alpha cells: * 20%. * ____. * Beta cells: * 80%. * ____. * Delta cells: * 10%. * ____ and somatostatin. * F cells: * 2%. * Pancreatic ____. • Islets composed of ○ Core § Mostly composed of ____ cells § Produce insulin ○ Mantle (surrounds the core) § Heterogenous mix of alpha, delta and f cells that produce different types of hormones • Out of each islet 80% are beta and only 20% are alpha cells

``` glucagon insulin gastrin polypeptide beta ```