Anat 4.4 Accessory Organs of the GIT_Calilao

7/25/2019 Anat 4.4 Accessory Organs of the GIT_Calilao

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Anatomy 4.4 November 15, 2011

Accessory Glands of the GIT Dr. Melissa Calilao

Group 17 | Esguerra, Eslao, Esling, Espelimbergo, Esternon, Estevanez, Estrada, Estrellado Page 1of 11

OUTLINE

I. Salivary Glands

a) Functions

b)

Types of Cells

c)

Interlobular Ducts

d) Types of Salivary Glands

e) Major Salivary Glands

II. Livera)

Functions

b) Surface of the Liver

c) Peritoneal Attachments

d)

Divisions of the Liver

e)

Blood Vessels

f) Portocaval Anastomoses

g) Lymphatic Drainage

h)

Nerve Supply

i)

Biliary Tract

j)

Liver Histology

III. Gallbladder

a) Parts

b)

Cystic Duct

c)

Blood Supply and Lymphatic Drainage

d)

Nerve Supply

e) Histology

IV. Pancreas

a)

Relationsb)

Parts

c) Pancreatic Duct

d) Arterial Supply

e)

Venous Drainage

f)

Lymphatic Drainage

g) Nerve Supply

h) Exocrine Functions

i)

Endocrine Functions

Objectives:

Enumerate the major salivary glands and classify each based on the nature of its secretion.

State the important anatomic relationships, surfaces and peritoneal attachments of the liver.

Differentiate between classical and functional divisions of the liver.

Describe the circulation of blood within the liver.

Describe the intrahepatic biliary flow.

Enumerate the sites of portocaval anastomoses and explain the clinical significance of such.

Describe the innervation, blood supply, and lymphatic drainage of the liver. Describe the location of the gallbladder and its anatomic relations.

Describe the innervation, blood supply and lymphatic drainage of the gallbladder.

Identify parts of the extrahepatic biliary system.

State the relations between the CBD and pa ncreatic duct as they open into the 2nd

portion of the duodenum.

Describe the pancreas and its location, as well as its parts and noting important anatomic relations.

State the exocrine and endocrine functions of the pancreas.

Describe the innervation, blood supply and lymphatic drainage of the pancreas.

I. SALIVARY GLANDS

A. FUNCTIONS

Wet and lubricate the oral cavity and its contents

Initiate the digestion of carbohydrates

Secrete substances such as:

o

IgAMajor immunoglobulin found in secretions thatprotects mucosal surfaces against pathogens

o Lysozymeshydrolyze the walls of certain bacteria

o Lactoferrinbinds iron, a nutrient necessary for bacterial

growth

Figure 1. Secretory Units

B. TYPES OF CELLS (SECRETORY UNITS)

Serous cells

o

usually pyramidal in shape, with a broad baseo narrow apical surface with short, irregular microvilli

o rounded nuclei with basophilic cytoplasm

o usually form a spherical mass of cells called acinus or

alveolus with a small lumen at the center

Mucous cells

o cuboidal to columnar in shape

o nuclei are oval and pressed towards the base of the cells

due to presence of mucous in the cytoplasm

o often organized as tubules, consisting of cylindrical arrays

of secretory cells surrounding a lumen

Figure 2. Epithelial components of a submandibular gland lobule

C. INTERLOBULAR DUCTS (TUBULAR SYSTEM)

Intercalated ducts

o Where secretory end pieces empty into

o Lined by simple cuboidal epithelial cells, with

presence of striations

o Empty into or join to form striated ducts


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Group 17|Esguerra, Eslao, Esling, Espelimbergo, Esternon, Estevanez, Estrada, Estrellado Page 2 of 11

Striated ducts

o Characterized by radial striations that extend to form

the bases of the cells to the level of the central nuclei

Radial striationsplasma membrane infoldings

with elongated mitochondria that are aligned

parallel to the infolded membranes

o Cells are columnar in shape

o Striated ducts of each lobule converge and drain into

interlobular or excretory ductslocated in the CT

septae separating the lobules; initially lined with

pseudostratified or stratified cuboidal epithelium,distally lined with stratified columnar epithelium

o Myoepithelial cellspresent in basal lamina of

glands or ducts which function to propel secretions

upon contraction

D. TYPES OF SALIVARY GLANDS

Minor salivary glands

o Scattered within palatine cavity only

o Named according to location

o Secrete only 10% of the total volume of saliva, but

account for approximately 70% of the mucous

secreted

o Under local neural control

Major salivary glands

o Secrete in response to parasympathetic activity

induced by physical, chemical, and psychological

stimuli

o Large, include the Parotid,

Submandibular/Submaxillary, and Sublingual Glands

E. MAJOR SALIVARY GLANDS (3 PAIRS)

Figure 3. Salivary Glands

I. Parotid Glands

Gross

oLargest of the salivary glands

o

Wedge-shaped

oSituated below the external auditory meatus

oLies in a deep hollow behind the ramus of the mandible, and

in front of the sternocleidomastoid muscle

oSecretes 25% of total saliva

o Stensens/Parotid duct emerges from the anterior border of

the gland, runs toward the lateral surface of the masseter

muscle, pierces the buccinator muscle, opens opposite the

upper 2nd

molar tooth, into the parotid papilla of the oral

cavity

Histology

oMorphology: Compound tubulo-alveolar gland or

branched tubulo-acinar gland

oNature of secretion: purely serous

oWhite structures are fat cells

oBasophilic cytoplasm

oRounded nucleus at base

oHigh in Alpha amylase and proline-rich proteins, which are

antimicrobial and have calcium-binding property

oParotid glands may become acutely inflamed as a result of

retrograde bacterial infection from the mouth via theparotid duct

oMay also become infected via the bloodstream, as in

mumps

Figure 4. Parotid Gland

(L-lobules, each containing many secretory units; S-supporting tissue septa,

conveying blood vessels, nerves and large E- excretory ducts)

Arterial supply

- External carotid artery (ECA) and its superficial

terminal branches (Superficial temporal and maxillary

aa.)

Venous drainage

- Retromandibular v.

Lymphatic drainage

-

Parotid and Deep cervical nodes

Nerve supply

oParasympathetic:Secretomotor supply from the

glossopharyngeal nerve (via the tympanic branch, the

Lesser Petrosal nerve, the Otic ganglion, and the

Auriculotemporal nerve)

oSympathetic: Plexus around ECA

II. Submandibular/Submaxillary glands

Gross

o Partly below the mandible

o Seen in the submandibular triangle

Histology

o Whartons Duct

obranched tubuloacinar gland, both mucous and serous,

predominantly serous with basophilic cytoplasm

o secretes lyzozyme

o goes along with the tongue and empties into the

sublingual caruncle


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oproduces 70% of total saliva

o Striated ducts are larger than in sublingual glands

(predominantly mucous glands)

o Determines the role of the striated duct in modifying

isotonic basic saliva to produce hypotonic saliva

Figure 5. Submandibular glands

Arterial Supply and Venous drainage

- Facial & Lingual (artery & vein)

Lymphatic drainage

-

Retromandibular and Deep cervical nodes

Nerve supply

o Parasympathetic: secretomotor supply is from the

facial nerve via the chorda tympani & the

submandibular ganglion (Superior Salivary nucleus of

CN VII)

o Sympathetic: Plexus around facial and lingual a.

III. Sublingual glands

Gross

oSmallest

oSeen on the floor of mouth, beneath mucus membrane,

close to the midline

o8-20 sublingual ducts which empty into sublingual folds

but a few may open into the sublingual caruncle

oSecretes 5% of the total saliva

Figure 7. Location of sublingual duct openings

Histology

obranched tubulo-acinar gland formed of serous and

mucous cells

omucous cells more predominant

o serous cells are present almost exclusively on demilunes

of mucous tubules

oHistologically lung-like appearance

Figure 6. Sublingual gland

Arterial Supply and Venous Drainage

- Facial and Lingual artery and veins

Lymphatic drainage

- Submandibular and Deep cervical nodes

Nerve supply

oParasympathetic: Secretomotor supply is from the facial

nerve via the chorda tympani & the submandibular

ganglion (Superior Salivary nucleus of CN VII) (increasessecretions)

oSympathetic: Plexus around facial and lingual a. (Decreases

secretion)

*In the human submandibular and sublingual glands,serous and

mucous cells are arranged in a characteristic pattern. The mucous

cells form tubules, but their ends are capped by serous cells,

which constitute the serous demilunes

CLINICAL CORRELATION

Xerostomiaor dry mouth is associated with difficulties in chewingswallowing, tasting, and speaking, dental caries, and atrophy othe oral mucosa. It is a chronic autoimmune disorder characterized

by lymphocytic infiltration of the exocrine glands, particularly thesalivary and lacrimal gland

II. LIVER- Largest mass of glandular tissue in the body

-

Largest internal organ: 1.5 kg

- Found in the abdominal cavity beneath the diaphragm

-

lies mainly in the RUQ

occupies most of the Right hypochondrium and upper

epigastric

extends into the left hypochondrium

- Biliary ducts: Right and left join to form the common hepatic

duct

- Common/bile duct: hepatic duct + cystic duct

-

Blood supply:

Portal vein70-80%

Hepatic artery20%

A. FUNCTIONS

Aids in the emulsification of fat

Produces bile

Filtration of blood

Heparin synthesis


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B. SURFACE OF THE LIVER

oDiaphragmatic surface

Convex, smooth

Subphrenic recesses : superior extensions of the peritoneal

cavity

oSeparated into right and left by the falciform ligament

Subhepatic space: supracolic compartment inferior to the

liver

Hepatorenal recess (Hepatorenal pouch/Morison pouch):

posterosuperioir extension of the subhepatic space

o

Fluid draining from the omental bursa flows here anterior layer is continuous on the left with the right

layer of the falciform ligament

posterior layer is continuous with right layer of the

lesser omentum

* all recesses of the peritoneal cavity are potential spaces with

enough peritoneal fluid for lubrication

oAnterior aspect

oPosterior aspect

oVisceral (posteroinferior)

Flat; concave

Covered with peritoneum except at the bed of the

gallbladder and the portahepatis

Portahepatis: transverse fissure in the middle visceral

surface of the liver

oGives passage to the portal vein, hepatic artery, hepatic

nerve plexus, hepatic ducts, and lymphatic vessels

oRelated to:

Right kidney

Right suprarenal gland

Hepatic flexure

Duodenum

Gallbladder

Fundus of the stomach

Abdominal esophagus

o

Impressions

Renal

Esophageal

Duodenal

Colic

Fecal

Gastric

Suprarenal

Visceral surface shows an H-shaped pattern (2 vertical limbs

and 1 horizontal limb)

oLeft limb of the H

Divides surface into right and left lobes

Fissure for ligamentumtereshepatis (remains of the left

umbilical vein)

Fissure for ligamentumvenosum ( remains of theductusvenosus)

oRight limb of the H

Gallbladder fossa - Between the right lobe and quadrate

lobe

Sulcus for inferior vena cavabetween the right lobe

and caudate lobe

oHorizontal limb of the H

the portahepatis or hilum of the liver

between caudate and quadrate lobe

C. PERITONEAL ATTACHMENTS OF THE LIVER

Falciform Ligament

o attaches the liver to the anterior wall of the abdominal

cavity up to the level of the diaphragm

o its free edge forms the ligamentum teres

o passes on to the anterior and then the superior surfaces

of the liver then splits into 2 layers

right layer: forms the upper layer of the coronary

ligament;free margin forms the right triangular

ligament

left layer: forms the upper layer of the left

triangular ligament

Coronary ligament: has an upper and lower layer which

encloses an area of the liver devoid of peritoneum known as

the bare area; attaches the right lobe of the liver to the

diaphragm

Right triangular ligament: V-shaped fold of peritoneum

formed by the right extremity of the coronary ligament;

connects the posterior surface of the right lobe of the liver to

the diaphragm

Left triangular ligament: attaches the left lobe of the liver to

the diaphragm; communicate with appendix fibrosa at the left

tip of liver

Areas devoid of Peritoneum

o

Bare area

oArea proximal to the inferior vena cava

oGallbladder in contact with liver bed

oPortahepatis

D. TYPES OF DIVISIONS OF THE LIVER& LOBES OF LIVER

Table 1. Liver lobe divisions

Classical Functional

Lobes Right Lobe:

subdivided into

quadrate and caudate

Left lobe

Left Lobe: including

quadrate and

caudate lobes

Right lobe

Lobes of liver

oRight lobe

larger than the left lobe

blood supply of functional right lobe: right hepatic artery

venous and lymphatic drainage: right hepatic vein and

hepatic duct

oLeft lobe

extends to left hypochondrium

reaches the upper border of the 6

thrib

blood supply: left hepatic artery

venous and lymphatic drainage: left hepatic vein and

hepatic duct

oQuadrate lobe

lower portion of the classical right lobe

oCaudate lobe

upper portion of the classical right lobe

*refer to appendix for summarized table


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Figure 8. Liver divisions

E. BLOOD VESSELS OF THE LIVER

Hepatic Portal vein

oBring 75-80% of blood to the liver

o

portal blood, containing about 40% more oxygen than bloodreturning to the heart from the systemic circuit to sustain the

liver parenchyma.

o it is formed by superior mesenteric and splenic veins posterior

to the pancreas.

o it ascends anterior to the IVC as part of the portal triad in the

hepatoduodenal ligament.

Hepatic artery

o it accounts for 20-25% of blood receives by the liver to non-

parenchymal structures particularly the intrahepatic bile

ducts.

o it is a branch of the celiac trunk maybe divided into:

Common hepatic artery- from celiac trunk to the

origin of the gastroduodenal artery.

Hepatic artery proper-from the gastrdoudenal arteryto the bifurcation of the hepatic artery

F. PORTOCAVAL ANASTOMOSES

- Portal hypertension may be caused by block in intrahepatic portal

vein tree, cirrhosis, impaired outflow of blood from the liver,

excessive flow of splanchnic or hepatic arterial blood to the liver

Esophageal

o Esophageal branches of left gastric (portal) with

esophageal veins draining middle 3rd

of esophagus

(systemic)

o Esophageal varicosities: esophageal hemorrhage : most

dangerous complication of the portal HPN

Rectal

o

Superior rectal veins (portal) with middle and inferior

rectal veins (systemic)

o Superior rectal veins (portal) with middle and inferior

rectal veins (systemic)

o Hemorrhoidal piles: swollen/inflamed vascular structures

in the anal canal

Para-umbilical

o Paraumbilical veins(portal) with superficial veins of

anterior abdominal wall (systemic)

o Caput Medusae: distended and engorged paraumbilical

veins radiating from the umbilicus

Retroperitoneal anastomosis

o veins of ascending colon, descending colon, duodenum,

pancreas and liver (portal) with renal, lumbar and phrenic

veins (systemic)

o retroperitoneal varicose portocaval anastomosis

G. LYMPHATIC DRAINAGE

The lymphatic vessel of the liver occurs as:

o Superficial lymphatics (in fibrous capsule of the liver)

which forms its outer surface drains to hepatic lymph

nodeso Deep lymphatics (in connective tissue) which accompany

the ramification of the portal triad and hepatic veins.

Space of Mall

o lymph from sinusoids is brought to an area between the

stromal of periportal area and hepatocytes

oBetween the outermost hepatocytes and stroma of the

portal triad

o it travels with the portal triad but in different direction

Celiac nodes

omajority of the lymph vessels from the liver enter the lymph

nodes in the portahepatis and eventually pass to the celiac

nodes

Posterior mediastinallymph nodes

o

vessels from the bare area of the liver pass through the

diaphragm to the posterior mediastinal lymph nodes

Lymph Flow : Portal area (space of mall)hepatic lymph nodes

celiac lymph nodes cisterna chyli of the thoracic duct

H. NERVE SUPPLY

The nerves of the liver are derived from the hepatic plexus

which accompanies the branch of the hepatic artery and

hepatic portal vein.

o hepatic plexus

Sympathetic fibers from celiac plexus

Parasympathetic fibers from the anterior vagal trunk

I. BILIARY TRACT

Bile

o produced by hepatocytes

o golden yellow or greenish yellow

o alkaline water containing sodium bicarbonate, bile salts,

bile pigments, cholesterol, lecithin and mucin

o aids in the breaking down of fats

o stored and concentrated (thru absorption of water and

salts) in the gallbladder when digestion is not take place

o first collected by the bile cannaliculi or bile capillaries

between hepatocytes

Common bile duct drains into 2nd

part of the duodenum at the

ampulla of vater.

J. LIVER HISTOLOGY

i. STRUCTURAL ORGANIZATION

STROMA

o Glissons Capsule: thin connective tissue

o Thicker at hilum

o

Vessels and ducts covered with connective tissue all the

way to termination/origin


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PARENCHYMA

o

Organized plated of hepatocytes:

80% liver cell population

1-2 spherical nuclei with nucleoli

Acidophilic cytoplasm with basophilic bodies

Numerous microvilli

Organelles:

-

Rough ER - sites for synthesis of plasma proteins

(albumin, fibrinogen, prothrombin and lipoprotein)

-

Smooth ERimportant in CHO metabolism, bileformation, catabolism of drugs and other toxic

substances; also site of VLDL synthesis

-

Golgi complexesimportant in concentrating and

packaging secretory products

- Mitochondriaenergy production

- Lysosomesfor turnover and degradation of

organelles

-

Peroxisomesoxidative metabolism of lipids, purines

& alcohol; participate in cholesterol and bile acid

synthesis

Bile canaliculus

-

tubular space between two abutted hepatocytes,

which forms a complex of anastomosing network

-

Empties from the canals of Hering to preductules ofcholangioles into bile ductules which then end in the

into bile ductsin the portal spaces

-

Bile ducts gradually enlarge and fuse to form the right

and left hepatic ducts, which subsequently leave the

liver as the common hepatic duct

- Bile flow opposite of blood flow: center to periphery

SINUSOIDAL CAPILLARIES

o Sinusoids

o Vascular channels between plates of hepatocytes that are

lined by fenestrated endothelium

o Contain Kupffer cells: macrophages that belong to the

mononuclear phagocyte system that metabolize aged

RBCs, digest hemoglobin, secrete proteins related toimmunological processes and destroy bacteria(later sent

to space of Disse)

PERISINUSOIDAL SPACE (SPACE OF DISSE)

o Where exchange of nutrients and waste products occur

o Subendothelial space that separates the endothelial cells

from the hepatocytes

ii. BLOOD SUPPLY

Portal Vein

o supply 80% of blood flow

o nutrient-rich but oxygen-poor

o from abdominal viscera

o

branches into portal venulesto the portal spaceso Portal Venules

obranch distributing venulesthat run around the

periphery of each lobule and lead into the sinusoids as

inlet venules

osinusoids: run radially, converging in the center to form

central or centrolobular venule

ocentral venules converge into sublobular veinsto form

large hepatic veins, which drains -> inferior vena cava

Figure 9. Intrahepatic vascular strucuture

Hepatic Artery20-30%

o Supply 20% of blood flow

o Oxygen-rich

o Branch of celiac plexus

o Ramifies parallel with portal veins branches, some of which

lead into the sinusoids

o In the hepatic sinusoids, there is mixing of arterial and portal

venous blood

Blood always flows from periphery to the center of each hepatic

lobule

o Intrahepatic vascular system: blood from portal vein and

hepatic artery is drained into the sinusoids central venule

sublobular vein hepatic vein IVC

iii. HEPATIC LOBULE

Functional units of the liver

Composed of hepatocytes arranged into polyhedral structures

Each lobule has three to six portal areas at its periphery and a

venule in the center (central vein)

The portal zones at the corners consist of connective tissue in

which the PORTAL TRIAD are embedded; portal triad consists

ofvenule (from portal vein), arteriole (from the hepatic

artery), and a branch of the bile duct(duct of cuboidal

epithelium)

Figure 10.Lobule structures

Hepatic Lobule Structure and Function

Classic Hepatic Lobule

oHexagon

oCenter: Central Venule

oAngles: portal canals

oBlood flow from 6 portal triad areas to a central venule

oEmphasizes endocrine function of liver

Portal Lobule

oTriangular

oCenter: Portal Triad

oAngles: Central Venule at each tip

oBile flow: from hepatocytes to bile duct of portal triad


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o Emphasizes major exocrine function of liver: bile

secretion

Liver Acinus

oDiamond or rhomboid in shape

smallest functional unit of hepatic parenchyma

oArea irrigated by terminal branch of the distributing vein

oShort axis: terminal branches of portal triad

oLong axis: line drawn between two central veins

oHas 3 zones:

o Zone I

-

periphery of classic lobule- get most oxygen and nutrients (1

stto receive)

- can most readily carry out oxidative metabolism

- 1st

to show morphologic changes after bile duct

occlusion

- Last to die if circulation impaired, but 1st

to

regenerate

o Zone II

- Middle

-

Have intermediate range of metabolic functions

o Zone III

-

closest to central venule

- most central part of classic lobule

-

get least oxygen and nutrients

-

preferential sites of glycolysis, lipid synthesis anddrug biotransformation

- 1st

to undergo fatty accumulation and ischemic

necrosis

-

Last to respond to toxic substances and bile stasis

Figure 11. Liver acinus

Liver Regeneration

Has extraordinary capacity for regeneration

Controlled by chalones

o Self-regulating

o Compensatory hyperplasiaa process in which the

remaining healthy hepatocytes begin to divide continuing

until the original mass of tissue is restored

Liver cirrhosis

o Continuous or repeated damage to hepatocytes over a

long period of time by various agents such as ethanol,

drugs or other chemicals, hepatitis virus (B,C, or D),parasites and autoimmune liver disease

o Formation of disorganized hepatocytes

o Causes liver failure, and is usually fatal

III. GALLBLADDER- Lies in the fossa for the gallbladder at the visceral surface of the

liver, located at the junction of the left and right lobe

- Pear-shaped sac

-

Can hold 30-50mL of bile

- Stores and concentrates bile

- Peritoneum completely covers the fundus of the gallbladder

and binds its neck and body to the liver

A. PARTS

FUNDUS: wide, blunt end that projects from the inferior lobe o

the liver at the right 9th

costal cartilage

BODY: main portion that contacts the liver, transverse colon, and

superior part of the duodenum

NECK: narrow, tapering end, opposite the fundus; directs to the

portahepatis and joins the cystic duct

INFUNDIBULUM/HARTMANNS POUCH: funnel shaped cavity

located close to the neck

Figure 12. Gallbladder

B. CYSTIC DUCT

Connects the neck of the gallbladder to the common hepatic duct

Passes between the layers of the lesser omentum, parallel to the

common hepatic duct, joining it to form the (common)bile duct

(cystic duct + common hepatic duct = common bile duct)

As the common bile duct, joins the pancreatic duct to form the

Ampulla of Vater, which opens into the 2nd

part of the duodenum

by the Major Duodenal Papilla; (common bile duct + pancreatic

duct = Ampulla of Vater)

Contains mucosal duplications forming the spiral fold/spiral valve

(of Heister) that regulates gallbladder filling and emptying; and

offers additional resistance to sudden bile dumping

C. BLOOD SUPPLY AND LYMPHATIC DRAINAGE

CYSTIC ARTERY

o Supplies the gallbladder and the cystic duct

o Arises from the Right Hepatic Artery in the

Cystohepatic Triangle of Calot (the triangle between

the common hepatic duct, cystic duct and viscera

surface of the liver/free edge)

CYSTIC VEINS

o Drains the neck of the gallbladder and cystic duct


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o Multiple, small veins that enter the liver after joining

the veins that drain the hepatic ducts and proximal

bile duct

o Veins from the fundus and the body of the gallbladder

pass directly into the hepatic sinusoids

LYMPHATIC VESSELS

o Drainage is through the Cystic lymph node, which

drains into the Hepatic lymph node, which then drains

into the Celiac lymph node

D. NERVE SUPPLY

The gallbladder and the cystic duct is supplied by the Celiac

Plexusformed by sympathetic and parasympathetic vagal fibers

Parasympathetic stimulation causes contractions of the

gallbladder and relaxation of the sphincters at the

hepatopancreatic ampulla.

CCK, produced by the enteroendocrine cells of the duodenum,

causes gallbladder contraction in response to consumption of

fatty food (stimulus)

Biliary tract pains are either circumscribed tenderness in the

gallbladder region or colicky pain.

Pain radiation: back, just below the tip of the right scapula,

right shoulder, substernal area, anterior left chest

E. GALLBLADDER HISTOLOGY

MUCOSA:

o Simple columnar epithelium with microvilli

o Tubuloacinar glands (mucous glands are present only in the

neck)

o Absence muscularis mucosa

o Lining epithelia with prominent mitochondria, microvilli and

intercellular spaces; indicative of absorptive cells (bile

concentration achieved through water absorption)

Absence of muscularis mucosa

Muscular Layer

o Discontinuous

o Inner layer: longitudinally oriented; outer layer:

diagonally oriented

Presence of Serosal layer

Rokitansky-Aschoff Sinuses: pseudodiverticula

True Ducts of Luschka: aberrant vestigial bile ducts

Figure 13. Types of ducts in gallbladder

F. EXTRAHEPATIC BILIARY SYSTEM

The right and left hepatic bile ductconverge to form the

common hepatic duct

The common hepatic duct and cystic ductcome together to

form the common bile duct

The common bile ductjoins the main pancreatic ductto form

theAmpulla of Vater, that enters the 2nd

part of the duodenum

through the major duodenal papilla

G.

PARTS OF THE COMMON BILE DUCT Supraduodenal

Retroduodenal

Infraduodenal

Intraduodenal

IV. PANCREAS-

Mixed exocrine-endocrine gland that produces digestive

enzymes and hormones

Exocrinepancreatic juice from acinar cells

Endocrineglucagon and insulin from pancreatic islets of

Langerhans

- An elongated structure that lies in the epigastrium and the left

upper quadrant- Soft and lobulated

- It crosses the pyloric plane (L1-L2 vertebral bodies) and situated

on the posterior abdominal wall behind the peritoneum

(retroperitoneal)

A. RELATIONS

Anteriorly (from (R) to (L)):

- Transverse colon

- Attachment of the transverse mesocolon

- Lesser sac

- Stomach

- Spleen

Posteriorly (from (R) to (L)):

- Bile duct

- Portal vein

- Splenic vein

- Inferior Vena Cava

-

Aorta

-

Origin of Superior Mesenteric Artery

- Left Psoas muscle

- Left suprarenal gland

B. PARTS

Figure 14. Pancreas


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HEAD

o Disc shaped and lies within the concavity of the duodenum

o A part of the head extend to the left behind the superior

mesenteric vessels and is called the uncinate process (or

lingula of the pancreas)

o It rests posteriorly on the IVC, right renal artery and vein,

and left renal vein.

o The bile duct lies in a groove on the postero-superior

surface of the head or is embedded in its substance

NECK

o

Constricted portion of the pancreas and connects the head

of the body

o Lies in front of the beginning of the portal vein and the

origin of the superior mesenteric artery from the aorta

BODY

o Runs upward to the left across the midline

o Lies to the left of the superior mesenteric vessels, passing

over the aorta and L2 vertebra.

o Sometimes triangular in cross section

o Lies in the epigastric area

o Comes in contact with hilum of spleen

TAIL

o Anterior to the left kidney and passes forward in the

splenicorenal ligamento Comes in contact with the hilum of the spleen

C. PANCREATIC DUCTS

Figure 15. Pancreatic Ducts

Main pancreatic duct (of Wirsung)

o Begins in the tail and runs the length of the gland,

receiving numerous tributaries

o Opens into the 2nd part of the duodenum about its middle

with the bile duct into a saclike dilatation called Ampulla

of Vater(aka Hepatopancreatic papilla) and into the Major

duodenal papilla

Sphincter of Oddi

o

Circular muscles fibers which surround the Ampulla ofVater and the terminal segments of the main pancreatic

duct and common bile duct

o Functions to contract the Ampulla of Vater to prevent the

throw of bile during the basal state

o Prevents reflux

o Presence of food relaxes the sphincter, allowing bile to

flow into the duodenum

o Without food, the sphincter is contracted

Accessory pancreatic duct (of Santorini)

o If present, drains the upper part of the head and then

opens into the duodenum about 2 cm above the main duct

on the minor duodenal papilla

o Frequently communicates with main pancreatic duct

D. ARTERIAL SUPPLY

Figure 16. Arterial supply of the pancreas

Derived mainly from the splenic artery

oHead & neck: (anterior and posterior) superior & (anterior

and posterior) inferior pancreaticoduodenal arteries

Superior pancreaticoduodenal a. is a branch of

gastroduodenal a.

Inferior pancreaticoduodenal a. is branch ofsuperior

mesenteric artery

o Body & tail: Splenic body from celiac artery

E. VENOUS DRAINAGE

Figure 17. Venous drainage of pancreas


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Pancreatic veinsTributaries of the splenic and superior

mesenteric parts of the portal vein but most empty into the

splenic veins

F. LYMPHATIC DRAINAGE

Pancreaticosplenic nodes

oMajor lymph drainage

oLie along the splenic artery

oMost vessels drain into these and some to the Pyloric lymph

nodes toward theceliac nodes or superiormesenteric nodes

o

Lymph nodes are situated along the arteries that supply the

gland

oVery extensive thats why carcinoma spreads easily

(intermingle with other lymph nodes)

CLINICAL CORRELATION

Cancer of the head of pancreasoften obstructs the bile ductand/or hepatopancreatic ampulla resulting in the retention of bilepigments, enlargement of the gallbladder, and obstructivejaundice. It may also cause obstruction of hepatic portal andinferior vena cava because it overlies these veins. Surgicalresection of the pancreas is futile because of its extensivedrainage in relation to its inaccessible lymph nodes andmetastasis to the liver occurs early, via hepatic portal vein. Lifeexpectancy for individuals afflicted with it usually is 2-3 months.

G. NERVE SUPPLY

Motor:

Sympathetic: Greater splanchnic (T5-T9)

Majority

Lesser splanchnic (T10-T11)

Decreases stimulation

Parasympathetic: Vagus n.

Stimulation

Increases enzyme content

Secretion is mediated by secretin and cholecystokinin

Sensory:

o Afferent fibers of sympathetic and vagal (parasympathetic)

pathways through the celiac ganglia to greater splanchnicnerves

o Pain is felt over the epigastrum and back area

Table 2. Summary of pancreas nerve supply/visceral referred pain

Origin Nerve SupplySpinal

Cord

Referred site &

clinical

example

Pancreatic

head

Vagus and

thoracic

splancnic nerves

T8-T9

Inferior part of

the epigastric

region (e.g.

pancreatitis)

Gallbladder

& Liver

Nerves derivedfrom celiac

plexus

(sympathetic),

vagus nerve

(parasympatheti

c), and right

phrenic nerve

(sensory)

T6-T9

Epigastric

region and

righthypochondriac

region; may

cause pain on

posterior

thoracic wall or

right shoulder

owing to

diaphragmatic

irritation

H. EXOCRINE FUNCTION

Composed of:

1.Pancreatic acinicomposed of several serous cells

2.Intercalated ductsmerge to form larger interlobar ducts

lined with columnar epithelium

Secretes pancreatic juice rich in bicarbonate ions (HCO3-) and

digestive enzymes (Proteases, Lipases, Nucleases and -

amylases)

Most proteases are stored as zymogen (inactive form) granules

of acinar cells

Centroacinar cells- constitute the intraacinar portion of the

intercalated duct and are only found in the pancreatic acini

I. ENDOCRINE FUNCTION

Composed of:

Islets of Langerhanscompact spherical masses of

endocrine tissue embedded within the acinar exocrine tissue.

o numerous in the tail region of pancreas

o arranged in cords separated by a network of

fenestrated capillaries

Table 3. Types of Cells found in the Islets

Cell Type Quantity

Hormone

Produced

Hormone

Function

Alpha Cells

~20% Glucagon Increases

blood glucose

content

Beta Cells

~70% Insulin Decrease

blood glucose

content

Delta Cells

~5-10% Somatostatin Inhibits

release of

other islet cell

hormones

Pancreatic

Polypeptide

Cells

(F Cells)

Rare Pancreatic

Polypeptide

Stimulates

activity of

gastric chief

cells


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APPENDIX:

Anatomical term Right lobe Left lobe Caudate lobe

Functional/surgical

term

Right (part of )the liver [Right portal lobe] Left (part of )the liver [left portal

lobe]

Posterior part of

the liver

Right lateral division Right medial

division

Left medial

devisor

Left lateral

division

Right

caudate

lobe

Left

caudate

lobe

Posterior lateral

segment

SEGMENT VII

[posterior superior

area]

Posterior lateral

segment VIII

[anterior superior

area]

[Medial superior

area]

Left medial

segment

SEGMENT IV

[medial inferior

area= =quadrate

lobe]

Lateral

segment

SEGMENT II

[lateral

superior area]

Posterior segment

I

Right anterior lateral

segment

SEGMENT VI

[posterior inferior

area]

Anterior medial

segment V

[anterior inferior

area]

Left lateral

anterior

segment

SEGMENT III

[lateral inferior

area]

Documents

Anat 4.4 Accessory Organs of the GIT_Calilao