Gastro

Reduce consumption of milk, or use lactase-treated products (example: yogurt-bacteria has already acted on the lactose and broken it down)

Adult hypolactasia: age-dependent loss of lactase. In some people, DNA variations on chromosome 2 (gene for lactase) causes complete inactivity so lactose cannot be broken down into galactose and glucose

maltase, isomaltase, sucrase and lactase

• vitamin C 
• gastric acid 
• low plasma iron, low ferritin levels-- secondary to blood loss, pregnancy, etc

In the meat form--it is highly absorbable but in the plant based form many things can affect its absorption--if plasma levels are high, oxalic acid in vegetables can bind the Fe and make insoluble complexes, excessive intake of calcium all reduce iron absorption

• both prefer acidic environments (why they wont work in the small intestine) and they work on short and medium fatty acid chains which are predominant in milk)--this helps in patients who do not make pancreatic lipase because there is still a backup system although not optimal

it is secreted by the small intestinal cells--and it is prevented from getting degraded by active trypsin because it is made up of sugars also

Yes--enzyme is located on the intestinal wall--but you might be producing inactive forms of the protein/not producing it at all: not necessarily bc of wall damage

because they are staying in the lumen it will cause more water to enter the lumen (diarrhea) 

bacteria also now get a substrate to ferment off of in the large intestine mainly--and will create lactic acid, gas (CO2, H2)...H2 is acidic so stool ph will be acidic and H2 gas can be measured on a breath test 

• -genetic deficiency, drugs 
• -chemotherapy (impairs the turnover of the intestinal cells-- damaged from acid and enzymes..so function is limited) 
• -intestinal disease-- affects the intestinal walls 

there are enzymes bound to the lumen mucosa which hang onto the disaccharides-- deficiency will prevent them from being broken down

salivary amylase inhibitor (salivary amylase issues will not cause deficiency of the nutrient but works to speed up the digestion) 

• • Slows down digestion of carbohydrates
• • Lengthens the time it takes for the digestion of carbohydrates
• • Keeps blood glucose from rising very high after meals

this medication becomes a problem when you have pancreas problems and cannot secrete pancreatic amylase

it is made with beta bonds-we dont have an enzyme that cleaves this-- it provides bulk and promotes regular BM-- bacteria breaks down cellulose in the large intestine creating flatus

alpha amylase will begin to break down sugars in the mouth by attacking the a-bonds--disaccharides (smallest unit) 

in the SI, you have amylase. and brush border enzymes which break down into monosac (galactose, glucose, and fructose)

the amount of volume that is ingested is only a fraction of the total secretions-- the majority of secretions come from the stomach, pancreas, liver, SI and is absorbed by the small intestine (mainly) and the large intestine 

• the major substance that is released is water which follows ions 
• and mucus 

A little bit can be absorbed throughout the small intestine, but there is a particular location for each nutrient where there is maximal absorption 

(Fat digestion maximal in the duodenum and absorption in the jejunum)

associates with R protein in the saliva and this protects it from the acidic conditions of the stomach-- stomach produces intrinsic factor

the R protein is broken down by trypsin in the small intestine and associates with the intrinsic factor for absorption where it is stored for much time in the liver

(Von Ebner’s glands)

foliate papillae are present in a greater abundance side by side 

• typically: stratified squamous epithelium 
• and then loose connective tissues
• and then skeletal muscle (darker) 

circumvallate papilla- they are laterally surrounded by deep ridges and have keratinized epithelia 

The deep trench surrounding the circumvallate papillae and the presence of taste buds on the sides rather than on the free surface are features that distinguish circumvallate from fungiform papillae.

foliate:

deep ridges, nonkeratinized epithelium-- foliate papillae 

also has long slender fingerlike projections extending from the connective tissue

the connective tissue rises into the papillae and it does not have the deep ridges laterally

• filiform papillae--the epithelial becomes pointy 
• does not contain taste receptors

lingual papillae (filiform, fungiform, foliate and circumvallate) and lingual tonsils.

All lingual papillae, except filiform papillae, contain test buds which include gustatory cells, which detect “flavors”

pepsinogen release--both are directly related--if production of one increases production of the other increases too

in the duodenum if the chyme is: (below) it will prevent gastric emptying, gastric acid/pepsinogen release 

• Hypertonicity 
• Acidity 
• Distention 
• Fatty Acids 
• Amino acids

• Always hypotonic:
• Na and Cl lower than plasma 
• K higher than plasma

volume depends on amount of cells stimulated and the stimuli

Lubricate the bolus for easy swallowing.

Dissolve substances for tasting.

• • Protect the oral cavity, teeth and esophagus (alkaline pH, lysozyme, lactoferrin, and R protein that protects
• vitamin B-12)

•amylase and lingual lipase (produced by Von Ebner's glands on the tongue)

Vasculature supplies the wall not the organs:

internal thoracic: gives the superior epigastric artery and the musculophrenic artery 

external iliac artery give the inferior epigastric artery

**T7-T12 and L1--travel from posterior to anterior bw internal and transverse oblique--innervating skin, muscles and parietal peritoneum of corresponding region  

T10 umbilicus and then count above and below

arcuate line

• First 3/4: covered by an anterior and posterior sheath
• the external and internal give anterior 
• the internal and transverse give posterior 

Last 1/4 does not have a posterior sheath--the external internal and transverse all make the anterior

protect the neurovasculature of the abdomen and provides compression and support to the abdominal organs

• Rectus abdominis: T7-T12
• -bilateral counterparts meet at the linea alba 
• -the muscle itself is sectioned off by tendinous intersections
• -flexion of the trunk  

Rectus sheath--the aponeurosis of the three muscles-- external internal and transverse oblique all meet here and create the sheath

• transversus abdominis: T7-T12, L1
• compresses the abdominal contents 
• both sides join at the linea alba

• internal oblique gives off a cremaster muscle 

• internal oblique- T7-T12 and L1 
• -aponeurosis meets at the linea alba 
• -Unilateral contraction causes lateral bend towards same side and turns the anterior part of the abdomen to the same side 
• -bilateral contraction caues trunk flexion

• External oblique: T7-12
• -end border marks the start of the inguinal ligament--on both sides the aponeurosis connects to form linea alba... 
• -bilateral contraction flexes the trunk and unilateral causes lateral flexion to the same side and anterior side turns to opposite

• -Skin 
• -Superficial fascia: Campers layer-fat layer located above and below the belly button AND Scarpa's layer: located below the belly button  
• -muscles 
• -transversalis fascia 
• -fat
• -parietal peritoneum

extends between the ASIS and the pubic tubercle, marking the end of the abdomen and the start of the thigh

highlighted in green= falciform ligament (ventral mesentery derivative) 

hanging from it is the round ligament of the liver which connects the liver to the umbilicus-- remnant of the umbilical vein)

testicular torsion--when the spermatic cord is tangled and this affects blood supply to the testicles along with the nerves that travel within this cord

• -ilioinguinal nerve (L1)--sensory 
• -genitofemoral nerve (L1 nad L2) contraction of the cremaster muscle to move testicle upwards 

you stroke the inner thigh (sensory input to nerve that causes movement of the testicle)

the deep inguinal ring--inferior epigastric vessels are located medially to the deep ring 

superficial inguinal ring 

• genitofemoral nerve 
• ilioinguinal nerve 

• round ligament of the uterus (women)
• spermatic cord (men)

• • Longest Branch of the celiac trunk         
• • runs along the superior border of the pancreas, posterior to the stomach

• o Left gastric artery → Supplies the lesser curvature of the stomach
•           ▪ Esophageal branch(es) → Supplies the abdominal esophagus

• o Splenic artery → supplies the spleen
•           ▪ Left gastroepiploic artery→ supplies greater curvature of stomach
•           ▪ Short gastric branches → supplies the fundus of the stomach

• o Common hepatic artery
•            ▪ Gastroduodenal artery → supplies the 1st and proximal 2nd part of the duodenum
•                 • Right gastroepiploic (gastro-omental) artery → supplies the pyloric end of the stomach
• and greater curvature of the stomach
•            ▪ Proper hepatic artery
•                 • Right gastric artery → supplies lesser curvature of the stomach
•                 • Right and left hepatic arteries → supply their respective lobes of the liver
•                 • Cystic artery → supplies the gallbladder (usually branches off the right hepatic artery)

duodenojejunal flexure and is surrounded by the ligament of treitz

duodenum:

• superior (right of L1)
• descending (Descendes down on right L1 to L3)
• horizontal (spans across L3)
• ascending -- and goes up to L2

• obesity 
• pregnancy 
• chronic cough 
• constipation

cardia of the stomach herniates through the esophageal hiatus of the diaphragm--can be asymptomatic can cause gerd too

the meeting of esophageal and stomach is marked by the Z LINE and is prone to esophageal cancer because of chronic gerd which causes metaplasia and then dysplasia

T10 esophageal hiatus and the abdomen contains the lower 1/3 of the esophagus

• esophagus 
• stomach
• the proximal part of the duodenum 

spleen 

• gallbladder
• pancreas
• liver

lesser sac: located behind the stomach/lesser omentum-- contains the pancreas, kidney--extends to the IVC 

• everything else is the greater sac 
• and both conjoin at the omentum foramen 

space that is confined amongst the IVC, the duodenum, the hepatoduodenal ligament and part of the liver-- the opening to this space is called the omental foramen (aka foramen of winslow, epiploic foramen 

left and right gastric vessels

• portal vein 
• bile duct 
• hepatic artery

attaches to the greater edge of the stomach and overs the small intestine and the transverse colon--made up of fat and connective tissue 

lesser omentum: attached to the lesser curve of the stomach and contains the hepatogastric and hepatoduodenal ligament

Outer two (red) medial umbilical folds: umbilical arteries 

median: urachus 

and 2 lateral umbilical folds (blue) inferior epigastric arteries and veins

muscular layers

• red: crypts of liberkuhn
• purple: muscularis mucosa 
• blue: bruners glands

duodenum 

• yellow: villi 
• mucosa has interstitial glands (crypts of liberkuhn)
• blue: brunner's glands in the submucosa

connective tissue (wavy more white spots) vs smooth muscle

nerve plexus near to the epithelial wall: Meissner

nerve plexus in the muscle layer-- Auerbachs plexus

enteroendocrine cells (argentarrif) that are stained--somatostatin, gastrin

• metoclopramide 
• domperidone

• – Restricted from CNS (BBB)
• -Withdrawn in US due to cardiac toxicity

Dopamine antagonist 

• – Readily crosses BBB
• – Adverse CNS effects: tremor,
• rigidity, dystonia, akathisia

– Directly stimulates motilin receptors on smooth muscle

• – Activate smooth muscle contraction via M3 receptors
• – Promote gastric, intestinal and colonic emptying

• Dopamine usually inhibits Ach release 
• so if you block dopamine you have more Ach which causes contraction

• opioids
• cholinergics and acetylcholinesterase inhibitors 
• dopamine antagonists

black stools that can be mistaken for blood

-coats ulcers and erosions

-stimulates prostaglandin, mucus, and bicarbonate secretion.

-reduces stool frequency and liquidity in acute infectious diarrhea

binds to prostaglandin receptors to increase mucus and bicarb secretion 

also binds Gi and causes decreased camp which causes decreased acid production 

DON'T GIVE TO PREGNANT FEMALES 

Sucralfate: binds to ulcers and acts as a covering preventing further damage 

protective agents they dont influence acid production

• • Cognitive dysfunction in elderly or patients with liver or kidney failure
• • Androgen receptor antagonist; may cause male gynecomastia, impotence
• • Inhibits CYPs and prolongs activity of other drugs

– Decreased absorption of calcium

-Rise in serum gastrin levels; hyperplasia of ECL and parietal cells and rebound acid hypersecretion

-Inflammation; accelerates gastric gland atrophy and intestinal metaplasia--because the bacteria is not being killed due to acid and subsequent inflammation can cause this

– Contraindicated in renal insufficiency

Particularly useful to treat chemotherapy-induced diarrhea

• – Stimulates motility of small intestine at low doses
• – Inhibits motility and intestinal secretions at high doses

– Cholestryamine, colestipol, colesevelam

used to decrease cholesterol levels but they also are used in treating diarrhea

• – Diphenoxylate
•            – May cause opioid dependence
•             • Combined with atropine to deter misuse
• – Loperamide
•                  – Does not cross BBB
•                  – Lacks analgesic activity
• – Eluxadoline

• Bloody diarrhea, high fever, systemic toxicity

• Classes of these medications 
• – Opioid agonists
• – Bile salt-binding resins
• – Octreotide
• – Anticholinergics

drugs binds the GC which increases cGMP production which adds CFTR receptors on the wall and releases Cl- into the lume

Serotonin binds to 5HT4 receptor to stimulate Ach release which causes motility-- used for treating constipation

cross the BBB

opioids normally prevent the release of Ach, decreased motility, constipation 

antagonists prevent opioids from binding and generating above effect 

• Methylnatrexone 
• Alvimopan

adds cl receptors on the apical side which causes water to enter the lumen--treatment for constipation

Docusate, glycerin suppository, mineral oil

• Psyllium,
• methylcellulose

Bulk-forming Laxatives

Osmotic Laxatives

–Polyethylene glycol--used for colonoscopy prep to clean out the GI Tract

sticky carbohydrate coats ulcers

vestibular-which causes motion sickness

postrema- detects stimuli from the brain or the CSF

GI: irritation in the GI tract sends messages to the brain via vagal nerve connections 

CNS stimuli

• lining in the middle: Taenia coli
• Epiploic (omental) appendages
• Haustra-Sacculations of the colon

• Blue: arcades
• purple: vasa recta

jejunum is redder, more circular folds, and is thicker than the ileum

• • 2/5 of the small intestine not including duodenum
• • Mostly located within the LUQ

• distal 3/5 of the small intestine
• • Mostly located within the RLQ

• • Distal 1/3 of the transverse colon
• • Descending colon
• • Sigmoid colon
• • Rectum
• • Anal canal

• • Distal 2nd, 3rd, and 4th parts of the duodenum
• • Jejunum
• • Ileum
• • Cecum
• • Appendix (if present)
• • Ascending colon
• • Proximal 2/3 of the transverse colon

• uncinate process 

common bile duct and the pancreatic duct meet to empty into the duodenum

left lobe is the smaller lobe

• Fundus: round part 
• body is the middle 
• and neck is the part that connects to the duct

ligamentum venosum is the remnant of the ductus venosus that shunts blood away from the liver during development

quadrate is closer to the gallbladder

• -Portal vein
• • Proper hepatic artery
• • Common bile duct

• -located in the right hypochondrium and
• epigastric regions

• diaphragmatic surface 
• bare surface-that is not covered by peritoneum

• •Foregut and Midgut: vagus nerve (CN X)
• •Hindgut: pelvic splanchnic nerves (S2-4)

• • Foregut: Sympathetic innervation provided by: Greater splanchnic nerve (T5-T9)
• o Ganglion where pre-ganglionic fibers synapse: Celiac ganglion
• • Midgut: Sympathetic innervation provided by: Lesser splanchnic nerve (T10-T11)
• o Ganglion where pre-ganglionic fibers synapse: Superior mesenteric ganglion

• • Hindgut: Sympathetic innervation provided by: Lumbar splanchnic nerves (L1-L2/3)
• o Ganglion where pre-ganglionic fiberssynapse: Inferior mesenteric ganglion

caput medusa-this is rare but when it occurs it is most often due to portal hypertension unlike hemorrhoids and esophageal varicoses that can occur due to other causes

due to blood building up in the rectal anastomoses--can be due to portal hypertension but can also be due to constipation because straining and causes increased abdominal pressure that causes portal venous system to be backed up and causes venous blood accumulation

• Portal venous system: 
• -splenic and superior mesentery veins are tributes to the portal vein 
• -inferior mesentery vein is a tribute to the splenic vein

• • Portal: Superior rectal veins →IMV
• • Caval: Inferior rectal veins →internal iliac vein

• • Portal: Paraumbilical veins →portal vein
• • Caval: Superficial abdominal veins → external iliac vein

• 1. Inferior esophagus
• 2. Rectum
• 3. Umbilicus

Marginal artery: 

-Travels along transverse colon

•middle colic and left colic arteries

•SMA and IMA arterial systems anastomose creating a collateral circulation bw midgut and hindgut

• -Left colic artery
• • Sigmoidal arteries
• • Superior rectal artery

Supplies the hindgut

• • Jejunal and ileal arteries
• • Middle colic artery
• • Right colic artery
• • Ileocolic artery

superior mesenteric artery comes out from underneath the pancreas and overlies the horizontal part of the duodenum

when two vessels are nearby--the thinner one is the vein and the thicker one is the artery

paneth cells

vein

Tongue has two different types of glands: 

• the darker ones: serous glands
• lighter ones: mucous glands

• artery= yellow 
• duct= red

Notice the cellular layering--duct

usually a lymph node has one layer of cells--you wouldn't see doubling like in here--but if there are blood cells in the lumen--then def a vein

capillary

present with hypoglycemia 

weight gain because eating to mantain sugars 

to diagnose: elevated serum insulin in setting of hypoglycemia during 72 hour fast--people who are taking insulin will have high insulin too but because its synthetic your c peptide and proinsulin will be low but in insulinoma they should be high 

isolated antral H pylori infection-- loss of D cells causes unregulated G cell secretion 

retained antrum after gastric surgery--nothing is producing acid 

gastric outlet syndrome 


have to r/o all these causes before giving a diagnosis of Zollingers-- based off a high serum gastrin, basal gastric acid output, and a high secretin stimulation test 

• multiple duodenal ulcers --because of this you can damage protein absorption--also because of the greater acid entering the duodenum, pH will be lower and inactivation of enzymes 
•            chronic diarrhea 
• erosive esophagitis

5-HIAA is a metabolite of serotonin-- serotonin release is increased in these tumors 

octreotide radioactive can be administered because it will bind to somatostain receptors which are present in great quantities in these cancer cells

you can also give octreotide to manage their diarrhea

• flushing 
• pellegra (skin conditions)
• wheezing
• palpitations 
• heart failure 
• diarrhea

receives a significant amount of the cardiac output and decreased blood pressure/flow doesn't affect until SBP falls below 70 because there are collaterals and an Extensive reserve: only 20% capillaries used

autosomal dominant in a tumor suppressor

• -nonfunctional does not secrete any hormones
• -gastrinoma (located in the pancreas or the duodenum)
• -insulinoma is the least common

affects the 

• pituitary (prolactinoma)
• parathyroid 
• pancreatic (there are many different types most common is nonfunctional pancreatic cancer)

-decreases insulin and gastrin release (DM)

-decreases GI motility (including gallbladder) (gallstones) 

-decreases pancreatic secretions (floating poop)

Glucagonoma Necrolytic migratory erythema-- rash that occurs due to decreased amino acids--amino acids are decreased because they are broken down to make more sugar

insulin stores glucose--- glucagonoma promotes gluconeogenesis -- increased blood glucose levels, increased weight loss because of breakdown to make glucose

there are poorly absorbed substances left within the lumen-in VIPoma its not an osmotic diarrhea bc large amounts of diarrhea despite fasting due to the ions moving into lumen

-diarrhea due to more chlorine in the lumen and the negative charge will force positive charge into the lumen also--hypokalemia--unlike the rest of the body, the GI tract has more potassium secretion, elsewhere there is usually sodium

• -inhibits gastric acid production 
• -increases CAMP in crypt cells to aid CL transport into the lumen

muscles that can lead to GI motility issues

mesenteric angiogram

• IV fluids due to the fluid loss 
• also antibiotics because when the mucosal barrier is damaged it is easier for bacteria to travel through the layers and access the bloodstream

Barrier Breakdown: The mucosa acts as a selective barrier, preventing large molecules, such as proteins, from leaking out of the blood vessels into the lumen. With ischemia, permeability increases, proteins escape into the colon.

Leakage into the Lumen: As a result of the weakened barrier, plasma proteins such as albumin leak from the bloodstream into the colonic lumen. This leads to the loss of proteins from the circulatory system.

• thumb printing 

common causes of colon ischemia

non-obstructive causes-- are more common 

• colon-water retention: solids are produced 
• solids exert a greater pressure and so squeeze the blood vessels against other structures

also not as well developed so less tolerable to ischemia

receive blood flow from 2 main arterial inputs and limitation of one of them leads these area more at risk for ischemia 

lower is because the iliac vessels will overlap-- the IMA supplies via the left colic, superior rectum, and the sigmoidal

in the colon---as you get older your inferior mesenteric artery gradually gets sclerotic and you become more dependent on the collaterals for blood flow--some patients don't have the marginal artery but in the cases of gradual scelorosing-- you have time to anastomically dilate... along with SMA, you also have internal iliac feeding in

persist because vasoconstriction in the abdomen has a late onset and late recovery

a surgical procedure that creates a connection between the stomach and the jejunum, the middle part of the small intestine