Section II

General Surgery

C h a p t e r 34

GI Hormones

and Physiology

OVERVIEW

Define the products of the following stomach cells:

Gastric parietal cells

Chief cells

G cells

Mucous neck cells

What is pepsin?

What is intrinsic factor?

HCl

Intrinsic factor

PEPsinogen (Think: “a PEPpy chief”)

Gastrin, G cells are found in the antrum (Think: G Gastrin)

Bicarbonate mucus

Proteolytic enzyme that hydrolyzes peptide bonds

Protein secreted by the parietal cells that combines with vitamin B12 and enables absorption in the terminal ileum

Name three receptors on the parietal cell that stimulate HCl release.

What is the enterohepatic circulation?

Where are most of the bile acids absorbed?

Think: “HAG”:

1.Histamine

2.Acetylcholine

3.Gastrin

Circulation of bile acids from the liver to the gut and back to the liver via the portal vein

Terminal ileum

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How many times is the entire Twice bile acid pool circulated

during a typical meal?

What are the stimulators of gallbladder emptying?

What are the inhibitors of gallbladder emptying?

CHOLECYSTOKININ (CCK)

Cholecystokinin, vagal input

Somatostatin, sympathetics (it is impossible to flee and digest food at the same time), vasoactive intestinal polypeptide (VIP)

What is its source?	Duodenal mucosal cells
What stimulates its release?	Fat, protein, amino acids, HCl
What inhibits its release?	Trypsin and chymotrypsin
What are its actions?	Empties gallbladder
	Opens ampulla of Vater
	Slows gastric emptying
	Stimulates pancreatic acinar cell growth
	and release of exocrine products
SECRETIN
What is its source?	Duodenal cells (specifically the
	argyrophilic S cells)
What stimulates its release?	pH 4.5 (acid), fat in the duodenum
What inhibits its release?	High pH in the duodenum
What are its actions?	Releases pancreatic bicarbonate/enzymes/
	H2O
	Releases bile/bicarbonate
	Decreases lower esophageal sphincter
	(LES) tone
	Decreases release of gastric acid
GASTRIN
What is its source?	Gastric antrum G cells

	Chapter 34 / GI Hormones and Physiology 201
What stimulates its release?	Stomach peptides/amino acids
	Vagal input
	Calcium
What inhibits its release?	pH 3.0
	Somatostatin
What are its actions?	Release of HCl from parietal cells
	Trophic effect on mucosa of the stomach
	and small intestine
SOMATOSTATIN
What is its source?	Pancreatic D cells
What stimulates its release?	Food
What are its actions?	Globally inhibits GI function
MISCELLANEOUS
What is the purpose of the	Reabsorption of H2O and storage of stool
colon?
What is the main small	Glutamine
bowel nutritional source?
What is the main nutritional	Butyrate (short-chain fatty acid)
source of the colon?
Where is calcium absorbed?	Duodenum actively, jejunum passively
Where is iron absorbed?	Duodenum
Where is vitamin B12	Terminal ileum
absorbed?
Which hormone primarily	CCK
controls gallbladder
contraction?
What supplement does a	Vitamin B12
patient need after removal
of the terminal ileum or
stomach?

202 Section II / General Surgery
Name the main constituents	Water, phospholipids (lecithins), bile
of bile.	acids, cholesterol, and bilirubin
What are most gallstones	Cholesterol
made of?
How do opiates affect the	By stimulating sodium absorption and
bowel?	inhibiting secretion in the ileum as well as
	decreasing GI motility by incoordinated
	peristalsis (Therefore, place patients on
	stool softeners when dispensing pain
	medication)

Which type of muscle fibers, smooth or striated, does the esophagus contain?

Which electrolytes does the colon actively absorb?

Which electrolyte does the colon actively secrete?

Which electrolyte does the colon passively secrete?

What is the gastrocolic reflex?

What is the blood supply to the liver?

Both:

Upper third—striated muscle control of motor nerves

Middle third—mixed

Lower third—smooth muscle, primarily under control of vagal motor fibers

Na , Cl

HCO3 (plays a role in diarrhea causing the patient to have a normal anion gap acidosis)

K

Increased secretory and motor functions of the stomach result in increased colonic motility

75% from the portal vein, rich in products of digestion

25% from the hepatic artery, rich in O2 (but each provide for 50% of oxygen)

What are Peyer patches? Nodules of lymphoid tissue with B and T lymphocytes in the small intestine that selectively sample lumenal antigens found in the terminal ileum

Chapter 35 / Acute Abdomen and Referred Pain 203

C h a p t e r 35

What is an “acute abdomen”?

What are peritoneal signs?

Define the following terms: Rebound tenderness

Motion pain

Voluntary guarding

Involuntary guarding

Colic

What conditions can mask abdominal pain?

What is the most common cause of acute abdominal surgery in the United States?

Acute Abdomen

and Referred Pain

Acute abdominal pain so severe that the patient seeks medical attention

(Note: Not the same as a “surgical abdomen,” because most cases of acute abdominal pain do not require surgical treatment)

Signs of peritoneal irritation: extreme tenderness, percussion tenderness, rebound tenderness, voluntary guarding, motion pain, involuntary guarding/ rigidity (late)

Pain upon releasing the palpating hand pushing on the abdomen

Abdominal pain upon moving, pelvic rocking, moving of stretcher, or heel strike

Abdominal muscle contraction with palpation of the abdomen

Rigid abdomen as the muscles “guard” involuntarily

Intermittent severe pain (usually because of intermittent contraction of a hollow viscus against an obstruction)

Steroids, diabetes, paraplegia

Acute appendicitis (7% of the population will develop it sometime during their lives)

204 Section II / General Surgery
What important questions	“Have you had this pain before?”
should be asked when	“On a scale from 1 to 10, how would you
obtaining the history of a	rank this pain?”
patient with an acute	“Fevers/chills?”
abdomen?	“Duration?” (comes and goes vs. constant)
	“Quality?” (sharp vs. dull)
	“Does anything make the pain better or
	worse?”
	“Migration?”
	“Point of maximal pain?”
	“Urinary symptoms?”
	“Nausea, vomiting, or diarrhea?”
	“Anorexia?”
	“Constipation?”
	“Last bowel movement?”
	“Any change in bowel habits?”
	“Any relation to eating?”
	“Last menses?”
	“Last meal?”
	“Vaginal discharge?”
	“Melena?”
	“Hematochezia?”
	“Hematemesis?”
	“Medications?”
	“Allergies?”
	“Past medical history?”
	“Past surgical history?”
	“Family history?”
	“Tobacco/EtOH/drugs?”
What should the acute	Inspection (e.g., surgical scars,
abdomen physical exam	distention)
include?	Auscultation (e.g., bowel sounds, bruits)
	Palpation (e.g., tenderness, R/O hernia,
	CVAT, rectal, pelvic exam, rebound,
	voluntary guard, motion tenderness)
	Percussion (e.g., liver size, spleen size)

What is the best way to have a patient localize abdominal pain?

What is the classic position of a patient with peritonitis?

“Point with one finger to where the pain is worse”

Motionless (often with knees flexed)

Chapter 35 / Acute Abdomen and Referred Pain 205

What is the classic position	Cannot stay still, restless, writhing in pain
of a patient with a kidney
stone?
What is the best way to	Use stethoscope to palpate abdomen
examine a scared child or
histrionic adult’s abdomen?

What lab tests are used to evaluate the patient with an acute abdomen?

What is a “left shift” on CBC differential?

CBC with differential, chem-10, amylase, type and screen, urinalysis, LFTs

Sign of inflammatory response: Immature neutrophils (bands) Note: Many call 80% of WBCs as

neutrophils a “left shift”

What lab test should every Human chorionic gonadotropin ( -hCG) woman of childbearing age to rule out pregnancy/ectopic pregnancy with an acute abdomen

receive?

Which x-rays are used to evaluate the patient with an acute abdomen?

How is free air ruled out if the patient cannot stand?

What diagnosis must be considered in every patient with an acute abdomen?

What are the differential diagnoses by quadrant?

RUQ

Upright chest x-ray, upright abdominal film, supine abdominal x-ray (if patient cannot stand, left lateral decubitus abdominal film)

Left lateral decubitus—free air collects over the liver and does not get confused with the gastric bubble

Appendicitis!

Cholecystitis, hepatitis, PUD, perforated ulcer, pancreatitis, liver tumors, gastritis, hepatic abscess, choledocholithiasis, cholangitis, pyelonephritis, nephrolithiasis, appendicitis (especially during pregnancy); thoracic causes (e.g., pleurisy/pneumonia), PE, pericarditis, MI (especially inferior MI)

206 Section II / General Surgery
LUQ	PUD, perforated ulcer, gastritis, splenic
	injury, abscess, reflux, dissecting aortic
	aneurysm, thoracic causes, pyelonephritis,
	nephrolithiasis, hiatal hernia (strangulated
	paraesophageal hernia), Boerhaave’s
	syndrome, Mallory-Weiss tear, splenic
	artery aneurysm, colon disease
LLQ	Diverticulitis, sigmoid volvulus,
	perforated colon, colon cancer,
	urinary tract infection, small bowel
	obstruction, inflammatory bowel
	disease, nephrolithiasis, pyelonephritis,
	fluid accumulation from aneurysm or
	perforation, referred hip pain, gynecologic
	causes, appendicitis (rare)
RLQ	Appendicitis! And same as LLQ;
	also mesenteric lymphadenitis, cecal
	diverticulitis, Meckel’s diverticulum,
	intussusception
What is the differential	PUD, gastritis, MI, pancreatitis, biliary
diagnosis of epigastric pain?	colic, gastric volvulus, Mallory-Weiss
What is the differential	Ovarian cyst, ovarian torsion, PID,
diagnosis of gynecologic	mittelschmerz, tubo-ovarian abscess
pain?	(TOA), uterine fibroid, necrotic fibroid,
	pregnancy, ectopic pregnancy,
	endometriosis, cancer of the cervix/
	uterus/ovary, endometrioma, gynecologic
	tumor, torsion of cyst or fallopian tube

What is the differential diagnosis of thoracic causes of abdominal pain?

What is the differential diagnosis of scrotal causes of lower abdominal pain?

MI (especially inferior), pneumonia, dissecting aorta, aortic aneurysm, empyema, esophageal rupture/tear, PTX, esophageal foreign body

Testicular torsion, epididymitis, orchitis, inguinal hernia, referred pain from nephrolithiasis or appendicitis

Chapter 35 / Acute Abdomen and Referred Pain 207

What are nonsurgical causes	Gastroenteritis, DKA, sickle cell crisis,
of abdominal pain?	rectus sheath hematoma, acute
	porphyria, PID, kidney stone,
	pyelonephritis, hepatitis, pancreatitis,
	pneumonia, MI, C. difficile colitis
What is the unique differential	In addition to all common abdominal
diagnosis for the patient with	conditions:
AIDS and abdominal pain?	CMV (most Common)
	Kaposi’s sarcoma
	Lymphoma
	TB
	MAI (Mycobacterium Avium
	Intracellulare)

What are the possible causes of suprapubic pain?

What causes pain limited to specific dermatomes?

What is referred pain?

Cystitis, colonic pain, gynecologic causes (and, of course, appendicitis)

Early zoster before vesicles erupt

Pain felt at a site distant from a disease process; caused by the convergence of multiple pain afferents in the posterior horn of the spinal cord

What is gastroenteritis? Viral or bacterial infection of the GI tract, usually with vomiting and diarrhea, pain (usually after vomiting), nonsurgical

What is classically stated to be the “great imitator”?

Name the classic locations of referred pain:

Cholecystitis

Appendicitis

Diaphragmatic irritation (from spleen, perforated ulcer, or abscess)

Constipation

Right subscapular pain (also epigastric)

Early: periumbilical

Rarely: testicular pain

Shoulder pain ( Kehr’s sign on the left)

Pancreatitis/cancer

Back pain

208 Section II / General Surgery

Rectal disease

Nephrolithiasis

Rectal pain

Small bowel

Uterine pain

Give the classic diagnosis for the following cases:

“Abdominal pain out of proportion to exam”

Hypotension and pulsatile abdominal mass

Fever, LLQ pain, and change in bowel habits

Give the test of choice for the following conditions:

Cholelithiasis

Bile duct obstruction

Mesenteric ischemia

Ruptured abdominal aortic aneurysm

AAA

Abdominal abscess

Severe diverticulitis

What is the most common cause of RUQ pain?

What is the most common cause of surgical RLQ pain?

Pain in the small of the back Testicular pain/flank pain Midline small of back pain Periumbilical pain

Midline small of back pain

Rule out mesenteric ischemia

Ruptured AAA; go to the O.R.

Diverticulitis

Ultrasound (U/S)

U/S

Mesenteric A-gram

NONE—emergent laparotomy

Abdominal CT scan or U/S

Abdominal CT scan

Abdominal CT scan

Cholelithiasis

Acute appendicitis

		Chapter 36 / Hernias 209
What is the most common	Diverticulitis
cause of GI tract LLQ pain?
Classically, what endocrine	1.	Addisonian crisis
problems can cause abdomi-	2.	DKA (Diabetic KetoAcidosis)
nal pain?

C h a p t e r 36	Hernias
What is a hernia?	(L. rupture) Protrusion of a peritoneal
	sac through a musculoaponeurotic barrier
	(e.g., abdominal wall); a fascial defect
What is the incidence?	5%–10% lifetime; 50% are indirect
	inguinal, 25% are direct inguinal, and
	5% are femoral
What are the precipitating	Increased intra-abdominal pressure:
factors?	straining at defecation or urination
	(rectal cancer, colon cancer, prostatic
	enlargement, constipation), obesity,
	pregnancy, ascites, valsavagenic (coughing)
	COPD; an abnormal congenital anatomic
	route (i.e., patent processus vaginalis)

Why should hernias be repaired?

What is more dangerous: a small or large hernia defect?

Define the following descriptive terms:

Reducible

To avoid complications of incarceration/ strangulation, bowel necrosis, SBO, pain

Small defect is more dangerous because a tight defect is more likely to strangulate if incarcerated

Ability to return the displaced organ or tissue/hernia contents to their usual anatomic site

Incarcerated	Swollen or fixed within the hernia sac (incar-
	cerated imprisoned); may cause intestinal
	obstruction (i.e., an irreducible hernia)

210 Section II / General Surgery

Strangulated

Complete

Incomplete

What is reducing a hernia “en masse”?

Incarcerated hernia with resulting ischemia; will result in signs and symptoms of ischemia and intestinal obstruction or bowel necrosis (Think: strangulated choked)

Hernia sac and its contents protrude all the way through the defect

Defect present without sac or contents protruding completely through it

Reducing the hernia contents and hernia sac

Chapter 36 / Hernias 211

Define the following types of hernias:

Sliding hernia Hernia sac partially formed by the wall of a viscus (i.e., bladder/cecum)

Littre’s hernia	Hernia involving a Meckel’s diverticulum
	(Think alphabetically: Littre’s Meckel’s
	LM)
Spigelian hernia	Hernia through the linea semilunaris
	(or spigelian fascia); also known as
	spontaneous lateral ventral hernia (Think:
	Spigelian Semilunaris)
Internal hernia	Hernia into or involving intra-abdominal
	structure
Petersen’s hernia	Seen after bariatric gastric bypass—
	internal herniation of small bowel
	through the mesenteric defect from the
	Roux limb
Obturator hernia	Hernia through obturator canal (females
	males)
Lumbar hernia	Petit’s hernia or Grynfeltt’s hernia
Petit’s hernia	(Rare) hernia through Petit’s triangle
	(a.k.a. inferior lumbar triangle) (Think:
	petite small inferior)
Grynfeltt’s hernia	Hernia through Grynfeltt-Lesshaft
	triangle (superior lumbar triangle)

212 Section II / General Surgery
Pantaloon hernia	Hernia sac exists as both a direct and
	indirect hernia straddling the inferior
	epigastric vessels and protruding through
	the floor of the canal as well as the
	internal ring (two sacs separated by the
	inferior epigastric vessels [the pant
	crotch] like a pair of pantaloon pants)

Inferior epigastric vessels

Direct	Indirect
hernia	hernia

Incisional hernia	Hernia through an incisional site; most
	common cause is a wound infection
Ventral hernia	Incisional hernia in the ventral abdominal
	wall
Parastomal hernia	Hernia adjacent to an ostomy (e.g.,
	colostomy)
Sciatic hernia	Hernia through the sciatic foramen
Richter’s hernia	Incarcerated or strangulated hernia
	involving only one sidewall of the bowel,
	which can spontaneously reduce, resulting
	in gangrenous bowel and perforation within
	the abdomen without signs of obstruction

	Chapter 36 / Hernias 213
Epigastric hernia	Hernia through the linea alba above the
	umbilicus
Umbilical hernia	Hernia through the umbilical ring, in
	adults associated with ascites, pregnancy,
	and obesity
Intraparietal hernia	Hernia in which abdominal contents
	migrate between the layers of the
	abdominal wall
Femoral hernia	Hernia medial to femoral vessels (under
	inguinal ligament)
Hesselbach’s hernia	Hernia under inguinal ligament lateral
	to femoral vessels
Bochdalek’s hernia	Hernia through the posterior diaphragm,
	usually on the left (Think: Boch da
	lek “back to the left” on the
	diaphragm)
Morgagni’s hernia	Anterior parasternal diaphragmatic
	hernia
Properitoneal hernia	Intraparietal hernia between the
	peritoneum and transversalis fascia
Cooper’s hernia	Hernia through the femoral canal
	and tracking into the scrotum or labia
	majus
Indirect inguinal	Inguinal hernia lateral to Hesselbach’s
	triangle
Direct inguinal	Inguinal hernia within Hesselbach’s
	triangle
Hiatal hernia	Hernia through esophageal hiatus
Amyand’s hernia	Hernia sac containing a ruptured appendix
	(Think: Amyand’s Appendix)