Abdomen and Cavity Grays

8/6/2019 Abdomen and Cavity Grays

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The Abdomen

Surface Anatomy, Vessels,

Muscles, and Peritoneum


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Abdominopelvic Cavity

Ventral body cavity

Thoracic

Abdominopelvic

Abdominopelvic

Abdominal Liver

Stomach

Kidneys

Pelvic cavity

Bladder

Some reproductive organs

Rectum


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AbdominopelvicCavity

Surrounded by theabdominal walls andpelvic girdle

The two cavities arecontinuous

Most organssurrounded by a

peritoneal cavity Visceral peritoneum

Serous peritoneum

Peritoneal cavity

pg242


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Abdominal Quadrants

9 regions

4 quadrants

Draw line through

navel Right upper

quadrant

Left upper quadrant

Left lower quadrant

Right lowerquadrant

pg


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Surface Anatomy

Anterior abdominal wallextends from costal marginto inferior boundaries: Iliac crest

Anterior superior iliac spine

Inguinal ligament Pubic crest

Superior boundary Diaphragm

Central landmark Umbilicus

Linea alba (white line) Tendinous line

Extends from xiphoid processto pubic symphysis

pg345


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Muscles

Function: Help contain abdominal organs

Move trunk

Forced breathing

Increase intra-abdominalpressure

Abdominal wall Anterior (4) Innervated by intercostal nerves

Continuous with layers ofintercostal muscles

Fibers of layers run in differentdirections for strength

Ends in aponeurosis which

contains rectus abdominismuscle

Posterior (3)

pg250


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Anterior Abdominal WallMuscles

Rectus Abdominis Origin

Pubic crest, symphysis

Insertion

Xiphoid process, costal cartilages ofribs 5-7

Function

Flex, rotate trunk, fix and depress ribs,stabilize pelvis, compress abdomen

Internal oblique

Origin

Lumbar fascia, iliac crest, inguinalligament

Insertion

Linea alba, pubic crest, last 3-4 ribs,costal margin

Function

Same for external obliques

pg 250,251


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Anterior Abdominal Wall

External oblique Origin

Lower 8 ribs

Insertion Aponeurosis to linea alba, pubic and

iliac crest Function

Flex trunk, compress abdominal wall(together), Rotate trunk (separatesides)

Transversus abdominis

Origin Inguinal ligament, lumbar fascia,

cartilage of last 6 ribs, iliac crest

Insertion Linea alba, pubic crest

Function

Compress abdominal contents

pg249


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Posterior Abdominal Wall Iliopsoas

Psoas major Origin

Lumbar vertebrae, T12

Insertion Lesser trochanter of femur via iliopsoas

tendon

Function

Thigh flexion, trunk flexion, lateral flexion Innervation Ventral rami L1-L3

Iliacus Origin

Iliac fossa, ala of sacrum

Insertion

Lesser trochanter of femur via iliopsoastendon

Function Thigh flexion, trunk flexion

Innervation Femoral nerve (L2 and L3)

Psoas minor variable (40-60% do nothave)pg

316


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Posterior Abdominal Wall

Quadratus lumborum Origin

Iliac crest and lumbar fascia

Insertion

Transverse process of upperlumbar vertebrae, lower marginof rib 12

Function Flex vertebral column, maintains

upright posture, assists ininspiration

Innervation:T12 and upper lumbar spinal

nerves (ventral rami)

pg


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Peritoneum

Mesenteries Double layer of peritoneum (2 serous membranes

fused together)

Extend to the digestive organs from the body wall

Function:Hold organs in place

Sites of fat storage

Provide a route for vessels and nerves

Dorsal mesenteries: Lesser omentum and Falciform ligament

Ventral mesenteries: Greater omentum, Transverse mesocolon, Mesentary, and

Sigmoid mesocolon


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Dorsal Mesenteries

pg 269 pg291


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Ventral Mesenteries

pg 269

pg 271


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Peritoneum

Peritoneal Remains surrounded by peritoneal cavity

Liver, stomach, ileum and jejunum

Retroperitoneal

Some organs lay behind/outside peritoneum Primarily retroperitoneal

Organs NEVER within the cavity

Kidneys, bladder, ureter

Secondarily retroperitoneal Organs once suspended within the abdominal cavity by mesentery

Migrate posterior to the peritoneum during the course ofembryogenesis to become retroperitoneal

Lack mesenteries

Duodenum, ascending and descending colon, rectum, pancreas


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pg 226


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Organs of the Abdomen

Urinary and Digestive

Systems


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Urinary System


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Urinary System

Kidney (2) Purify blood

Ureter (2)

Drains urine fromkidney to bladder

Urinary Bladder Stores urine

Urethra Drains urine from

bladder to outsidebody

pg 314


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Kidneys

Filter waste from blood

Water, toxins, urea, uric acid, creatinine,metabolic waste, ions

Excretion of waste Homeostasis

Acid-base balance

Blood pressure Plasma volume


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Kidneys: Gross Anatomy

Lie in retroperitoneal,superior lumbar region

Extend from T11 or T12to L3

Laterally convex,medially concave

Hilus Where blood vessels,

ureters, and nerves enterand leave kidney

Adrenal gland On superior portion

pg 325


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Kidney: Gross Anatomy

Separated into lobes

Blood supply

Renal artery and vein

hearts systematicoutput reaches the kidney

Innervation

Branches of renal plexus

pg 323


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Kidney: Gross Anatomy

Supportive tissue Renal capsule

DCT Adheres directly to

kidney surface Maintains shape and

forms barrier

Adipose capsule Perirenal fat Cushions kidney

Keeps kidney in place Renal fascia Pararenal fat

Cushions kidney Keeps kidney in place

Internal

External

pg 322


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Kidney: Internal GrossAnatomy

Cortex

Superficial

Lighter zone

Functional portion

Medulla

Deep

Darker zone Pyramid shaped

Contains collectingtubules

pg 323


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Kidney: Internal GrossAnatomy

Medullary pyramid Makes up the medulla

Base: against cortex

Apex: inward Papilla = tip

Drips urine into minor calyx

Calices Collect urine draining from papillae

and empty into renal pelvis

Major calices Branching extensions of renal pelvis

Minor calices Divisions of major calices

Surround papilla of pyramids

Collect urine from papilla Renal pelvis

Expanded superior part of ureterpg 323


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Kidney: Internal Vasculature

Renal arteries

Segmental arteries

Enter through the

hilus Branch into:

Lobar arteries

Interlobar arteries

Arcuate arteries At border of cortex

and medulla

Interlobular arteries

pg 323


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Kidney: MicroscopicAnatomy

Uriniferous tubules

Produces urine through filtration, reabsorption, andsecretion

2 major part:

Nephron Collecting duct


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Ureters

Carry urine from thekidneys to the bladder

Begins superiorly at L2 as acontinuation of renal pelvis

Opens into the bladder Retroperitoneal

Enters the bladder at anoblique angle This prevents backflow into

the ureters

Increased pressure inbladder lead to the distalend of ureter closing Not only gravity at work

here!!

pg 325


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Ureters: MicroscopicAnatomy

Another tubular organ!!

Mucosa Lamina epithelialis

Transitional epithelium

Stretches when ureters

are full Lamina propria

Muscularis Inner longitudinal

Outer circular

External longitudinal layer(inferior third)

Function in peristalsis

Adventitia CT


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Urinary Bladder

Stores and expels urine

Posterolateral angle receivesthe ureter

Inferior angle drains into theurethra

Located: Inferior to peritoneal cavity On pelvic floor

Posterior to pubic symphysis

Male: Anterior to rectum

Female: Anterior to vagina and uterus

pg 400


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Urinary Bladder

Full bladder expandsinto abdominal cavity

Empty bladder lieswithin pelvic cavity

Vasculature:

Internal iliac branches ofarteries and veins

Innervation:

Branches of thehypogastric plexus

pg 399


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Urinary Bladder: InternalAnatomy

Tubular organ!!!!!

Trigone area

3 layers: Mucosa

Transitional epithelium Lamina propria

Muscular layer Detrusor muscle (smooth);

3 layers:

Inner and outerlongitudinal, middle circular

Adventitia Fibrous CT

Parietal peritoneum onsuperior surfacepg 400


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Urethra

Drains urine frombladder to outside ofbody

Female:

Short tube

Male 3 regions

Prostatic urethra

Membranous urethra

Spongy/penile urethra

Opens at the externalurethral orifice

Also carries ejaculatingsemen

pg 400


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Urethra Landmarks

Internal urethral sphincter At bladder/urethral junction

Thickening of detrusor muscle

Involuntary; keeps urethra closed when urine is not beingpassed

Prevents dribbling!

External urethral sphincter Surrounds urethra within the urogenital diaphragm

Inhibits voluntary urination until ready

External urethral orifice Males:

End of the penile urethra

Females: Anterior to vaginal opening and posterior to clitoris

M l F l


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Males versus Females:

pg 403


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Micturition = Urination

Contraction of the detrusor muscle to raise intra-abdominal pressure

Controlled by the brain

Urine accumulation leads to distention of the bladder

Activates stretch receptors Send sensory impulses to micturition center (MC) in the

pons

MC sends signals to parasympathetic neurons Stimulate detrusor muscle to contract (involuntary)

Internal urinary sphincter opens (also inhibits sympatheticpathways that would prevent urination)


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Micturition = Urination

Other brain receptors (pons, cerebralcortex) can inhibit urination

Relaxing of the detrusor, keeping external

urinary sphincter closed

Voluntary contraction of abdominalwall muscles increases abdominal

pressure Voluntary relaxation of external

urethral sphincter


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Digestive System


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Digestive System

Alimentary Canal Mouth

Pharynx

Esophagus

Stomach Small Intestine

Large Intestine

Accessory Organs Teeth, Tongue

Salivary Glands Gallbladder

Liver

Pancreas

pg 222

i i


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Digestive Processes 6Steps

Ingestion Taking food into the mouth

Propulsion Movement of food through GI tract

Swallowing and peristalsis

Mechanical digestion Prepares food for chemical digestion Chewing, churning, segmentation

Chemical digestion Enzymes break down complex food molecules

Absorption

Digested end products from lumen to blood

Defecation Elimination of indigestible substances


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Alimentary Canal Wall

ANOTHER tubular organ!

Layers:

Mucosa

Epithelium

Lamina propria (MALT)

Lamina muscularis mucosa

Submucosa

CT with elastic fibers, nerves,vessels

Muscularis

Inner circular Outer longitudinal

Creates sphincters

Serosa / Adventitiapg 313


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Peristalsis vs Segmentation

Peristalsis

Propulsion

Adjacent segments of the alimentarycanal contract and relax

Moves food distally along the canal

Segmentation

Part of mechanical breakdown

Food-mixing process

Nonadjacent segments of the intestinealternatively contract and relax

Moves food on and back

Mixes rather than propels


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Innervation

Nerve plexuses Occur within wall of alimentary canal

Parasympathetic, Sympathetic, VisceralSensory fibers

2 types: Myenteric nerve plexus

Between 2 muscle layers of the tunica muscularis

Controls segmentation and peristalsis

Submucosal nerve plexus Between submucosa and muscularis mucosa

Signals glands to secrete and LMM to contract


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pg 313


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Innervtion

Enteric Nervous System (ENS) Internal neurons in wall of canal (100 million!!)

Within the above plexuses

Form independent arcs of sensory, intrinsic,and motor neurons

Controls glandular secretion, peristalsis,segmentation

Autonomic Nervous System speeds up orslows activity controlled by enteric systemAllows the CNS to influence it


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Stomach

J-shaped

Temporary storage tank

Regions: Cardiac

Cardiac orifice

Junction of esophagus Fundus

Under diaphragm

Body Large midportion

Pyloric

Ends at the stomach Pyloric sphincter

Greater curvature

Lesser curvature

pg 272


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Stomach Function

Storage of chyme Food paste

Breakdown of food proteins

Done by pepsin Protein-digestion under acidic conditions

Absorption of nutrients H

2O, electrolytes

Alcohol, other drugs Food remains for about 4 hours

Holds from 1.5 to 4 liters


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Small Intestine

Longest portion of GI tract

Site of most enzymatic digestion andabsorption of nutrients Bile: emulsifier (gallbladder, liver)

Enzymes (pancreas)

Undergoes segmentation Allows for an increase contact with intestinal walls

Peristalsis propels chyme through in about 3

to 6 hours 2.6 to 6 meters long!!


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Small Intestine

Location: From pyloric sphincter

to first part of thelarge intestine

Regions: Duodenum (5%)

Proximal

Jejunum (almost 40%) Middle

Ileum (almost 60%) Distal

pg 274


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Small Intestine

Duodenum C shaped Short, straight Mostly retroperitoneal Receives:

Digestive enzymes from pancreasvia main pancreatic duct Bile from liver via the bile duct

Ileum and jejunum Highly coiled Fewer modifications

Hang by mesentery in peritonealcavity Mesentery Arcades

Arteries + veins Nerves Store fat

pg 283

S ll I t ti I t l


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Small Intestine InternalAnatomy

Intestinal flora produces vitamin K

Epithelium: Simple columnar epithelium

with many modifications forabsorption

Lymph tissue in submucosa Muscularis externa has 2 layers

Innervation: Some parasympathetic

innervation from vagus

Arterial supply: Superior mesenteric

Rt (cranial)pancreaticoduodenal

pg 283


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SI Absorption Modifications

Length More length, more area for

absorption!

Circular folds Plicae circulares

Transverse ridges of mucosa

Increase surface area

Force chyme to slow down

Villi Move chyme and increase contact

Contain lacteals

Remove fat

Microvilli More increasing of the surfcae area

Modifications decrease distally


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Large Intestine

Regions:

Cecum

Vermiform appendix

Colon Ascending

Transverse

Descending

Sigmoid

Rectum

Anal Canal

pg 279


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Large Intestine

Functions:

Absorbs remainingnutrients

Most material largelydigested

Absorbs water andelectrolytes

Forms, stores and expels

feces from body Propulsion is slow and weak

through LI except for massperistaltic movements

pg 283


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LI: Internal Features

Intestinal flora

No intestinal villi or modifications forabsorption

Many goblet cells

Simple columnar epithelium except lower halfof anal canal

Significant lymph tissue in mucosa andsubmucosa

Muscularis mucosae has 2 layers

Some parasympathetic innervation fromvagus


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LI Special Features

Teniae coli 3 Longitudinal strips

Thickenings oflongitudinal muscle layer

Maintain muscle tone

Cause LI to pucker intosacs.

Haustra Saclike divisions

Epiploic appendages Fat-filled pouches of

visceral peritoneum

Hang from the intestinepg 279

Cecum and Vermiform


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Cecum and VermiformAppendix

Cecum Sac-like pouch (blind pouch)

Ileocecal valve 2 raised edges of the mucosa

Sphincter keeps closed until

food in stomach Prevents reflux of feces from

cecum to ileum

Vermiform Appendix Blind tube

Opens into cecum Contains large masses of

lymphoid tissue

pg 276


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Colon Segments

Ascending Right side of posterior

abdominal wall Makes right angle turn

Right colic / hepatic flexure

Transverse Extends left across the

peritoneal cavity Bends downward at the

spleen Left colic / splenic flexure

Descending Left side Sigmoid

S-shaped True pelvis

pg


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Colon Functions

Absorb H2O and electrolytes

Some digestion by bacteria

Mass Peristaltic Movements (2-3xday)

Moves through in 12-24 hours

1.5 meters


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Rectum

Joins with the sigmoidcolon

Descends into thepelvis

Complete and well-developed longitudinalmuscle layer

Rectal valves

3 transverse folds Prevent feces from being

passed along with gas

pg 283


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Anal Canal

Begins where rectum passesthrough the levator animuscle

Releases mucus to lubricatefeces

Internal anal sphincter Made of smooth muscle

Involuntary

External anal sphincter Made of skeletal muscle

Voluntary

Toilet training!!!

Stratified squamousepithelium at lower half

pg 398


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Defecation

Stretching of rectal wall initiates defecationreflex

Mediated by the spinal cord Parasympathetic reflex signals walls of sigmoid

colon and rectum to contract and anal sphinctersto relax

Involuntary

If not ready, reflective contraction ends and

rectum relaxes Reflex initiated again until you actually defecate

Contraction of diaphragm, levator ani andabdominal muscles assist Voluntary


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Accessory Digestive

Organs


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Liver

Largest gland in thebody! Weighs about 3 pounds

Highly vascular

Location: Inferior to diaphragm In right superior part of

abdominal cavity

Mostly upper rib cage

Functions: (Over 500!) Produce bile Pick up glucose

Detoxify poison, drugs

Produce blood proteins

pg 242


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Liver Gross Anatomy

2 surfaces: Diaphragmatic

Visceral

Lobes:

Right lobe Left lobe

Divided by: Falciform ligament on

diaphragmatic surface

Fissure on the visceral

surface Quadrate lobe

Caudate lobe Both part of left lobe and

visceral surface

pg 285

pg 287


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Liver Visceral Surface

Hepatic Vein (intoinferior vena cava)

Porta Hepatis

Hepatic Artery (from

abdominal aorta ) Hepatic Portal Vein

Carries nutrient-rich bloodfrom stomach andintestines to liver

Hepatic portal system = 2

capillary beds!

Hepatic Ducts (carry bile)

pg 286


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Gallbladder

Muscular sac Rests in depression of

right liver lobe

Has many ducts

associated with it Stores and

concentrates bile Breaks down fats

Emulsification

Produced in liver

Stored in gallbladder

Secreted in duodenum

pg 285

pg 287


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Gallbladder

Mucosa Simple columnar

epithelium

Lamina propria

Expandable mucosalfolds

Smooth muscle layer

Thick connective

tissue Covered by serosa inplaces

pg 287


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Bile Ducts

Hepatic duct Carries bile from

liver

Cystic duct

Joins hepatic ductfrom liver to formthe bile duct

Carries bile fromgallbladder

Common Bile duct Empties into the

duodenum

pg 289

pg 290


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Movement of Bile

Bile secreted by liver continuously Hepatopancreatic (Vater) ampulla

common bile + main pancreatic duct meetand enter duodenum

Sphincter of Oddi around it closed when bile not needed for digestion

Bile then backs up into gallbladder via cysticduct

When needed gallbladder contracts, sphinctersopen


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Pancreas

Both exocrine andendocrine gland

Exocrine Produce enzymes that

digest food

Endocrine Produce hormones that

regulate blood sugar(insulin and glucagon)

Secondarily

retroperitoneal Location: Curve of duodenum Extends to spleen

pg 288


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Pancreatic Ducts

Main pancreatic duct Extends length of pancreas Joins bile duct to form the hepatopancreatic ampulla Empties into duodenum

Accessory pancreatic duct

Lies in head of pancreas Drains into the main duct Enters duodenum also

pg 289


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Arterial Blood Supply to


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Arterial Blood Supply toAbdominal Viscera

All branches of Abdominal Aorta

Anastomoses

Left + Middle colic

Left + Right gastric Left + Right gastroepiploic

Cranial + Caudal pancreaticoduodenal

Deep Iliac Circumflex + Adrenolumbar

Remember your zoological roots: YOUMUST KNOW WHAT SUPPLIES WHAT!!


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Names give hints!

Hepato = liver

Pancreatico =pancreas

Cystic = gallbladder Gastro = stomach

Splenic = spleen

Adreno = adrenal gl

Lumbar = lumbarregion

Epiploic =membrane-covered

Mesenteric =

mesentery Duodenal =

duodenum

Ileo = ileum

Colic = colon

Rectal = rectum

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Abdomen and Cavity Grays

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