FIRST AID FOR THE USMLE
COMPREHENSIVE STUDY GUIDE 2026 FULL
QUESTIONS AND SOLUTIONS GRADED A+
◍ Red urine in the morning, fragile RBCs.
Answer: Paroxysmal nocturnal hemoglobinuria
◍ Which sprue affects the Duodenum more? Which sprue affects the I/J
more?.
Answer: Duodenum: Celiac SprueI/J: Tropical Sprue
◍ Back pain, fever, night sweats.
Answer: Pott disease (vertebral TB)
◍ For the following areas of the digestive tract, please provide the relevant
histological
structures:Esophagus:Stomach:Duodenum:Jejenum:Ileum:Colon:.
Answer: Esophagus: non-keratinized stratified squamous
epitheliumStomach: gastric glands-gastric pits=chief cellsDuodenum: villi
and microvilli serve to increase absorptive surface. Brunner glands (HCO3-
secreting cells of the submucosal and crypts of Lieberkuhn. Jejenum: plicae
circulares and crypts of lieberkuhnIleum: peyer patches and crypts of
lieberkuhnColon: crypts of lieberjuhn but no vili; abundant goblet cells
◍ Chronic PancreatitisWhat is it?Causes?Symptoms?Diagnosis?.
Answer: What is it?:- chronic inflammation, atrophy, calcification of the
pancreas- note that CTFR mutations can cause chronic pancreatic
insufficiencyCauses?- alcohol abuse and idiopathicSymptoms?- steatorrhea,
fat-soluble vitamin deficiency, diabetes mellitusDiagnosis?- amylase/lipase
may or may not be elevated (though are always elevated in acute
pancreatitis)
,◍ What is gastroschisis?Results from a defect in what stage of embryonic gut
development?.
Answer: What is gastroschisis?- extrusion of abdominal contents through
abdominal folds (usually right of umbilicus); NOT covered by
peritoneumResults from a defect in what stage of embryonic gut
development?- defect in lateral fold closure
◍ Infant with cleft lip/palate, microcephaly or holoprosencephaly, polydactyly,
cutis aplasia.
Answer: Patau syndrome (trisomy 13)
◍ Small, irregular red spots on buccal/lingual mucosa with blue-white centers.
Answer: Koplik spots (measles; rubeola virus)
◍ Infant with "cherry-red" spot on macula, hepatosplenomegaly, and
neurodegeneration.
Answer: Niemann-Pick disease (genetic sphingomyelinase deficiency)
◍ Walk through the breakdown/recycling of heme from RBCs to various
products by location:.
Answer: RBC ↓Heme ↓ (heme oxygenase)Biliverdin ↓Unconjugated
bilirubin ↓Bound to albumin ↓ (UDPGT)Conjugated Bilirubin ↓ (gut
bacteria)Urobilinogen ↓excreted as feces (stercobilin--OR--Recycled back
to liver--OR--Excreted in urin as urobilin
◍ What region of the brain controls hunger and fullness?.
Answer: The hypothalamus.The lateral hypothalamic area --> controls
sensations of hunger (ie: stimulates feeding)The ventromedial nucleus of the
hypothalamus (VNH) --> controls sensations of fullness (ie: tells a person to
stop feeding)
◍ Polyuria, renal tubular acidosis type II, growth failure, electrolyte
imbalances, hypophosphatemic rickets.
Answer: Fanconi syndrome (multiple combined dysfunction of the PCT)
◍ Visceral vs Parietal Pain.
, Answer: - differential innervation of the visceral and parietal pleura result in
different types of pain Visceral Pain- transmitted via type C fibers- colicky,
cramping, poorly localized painParietal Pain- parietal peritoneum is
innervated by extensions of the peripheral spinal nerves, which carry the
same types of noxious pain sensations as those overlying the
dermatomes-sharp and localizedThus if the pathologic process progresses
from visceral to the parietal region, the referred pain will become localized,
corresponding to the dermatome overlying the affected organ
◍ What is Zollinger-Ellison syndrome?.
Answer: What is Zollinger-Ellison syndrome?- caused by gastrin secreting
neuroendocrine tumors (gastrinomas) that are most commonly located in the
small intestine or pancreas- gastrin produced by these tumors often leads to
excess gastric acid production resulting in multiple peptic ulcers that can be
located beyond the duodenal bulb (closest part to stomach)Can also have:-
abdominal pain- reflux- diarrhea (due to inactivation of pancreatic/intestinal
exnymes by gastric acid)Diagnosis:- secretin stimulation test: basal and
stimulated gastrin levels- also should undergo testing to exclude MEN 1
◍ Which ligament connects the liver to anterior abdominal wall?.
Answer: Falciform ligament
◍ Muffled heart sounds, distended neck veins, hypotension.
Answer: Beck triad of cardiac tamponade
◍ For the following salivary gland tumors, provide their commonality, and
histological features:Pleomorphic adenomaMucoepidermoid
carcinomaWarthin tumor.
Answer: - salivary gland tumors are most commonly benign in the parotid
gland - tumors in smaller glands are more likely malignant- typically present
as a painless mass/swelling- the presence of facial pain or paralysis suggests
malignant involved of CN VIIPleomorphic adenoma:- benign mixed tumor-
most common salivary gland tumor- made of chondromyxoid stroma and
epithelium - recurs if incompletely excised or ruptured
inraoperativelyMucoepidermoid carcinoma:- most common malignant
, tumor- has mucinous and squamous componentsWarthin tumor:- aka
papillary cystadenoma lymphomatomsum- benign cystic tumor with
germinal centers-SMOKERS
◍ What is bile and how is it made?What makes it?What are its primary
functions?.
Answer: What is bile?bile salts (bile acids +
glycine/taurine)phospholipidscholesterolbilirubinH20ionsWhat makes it?-
hepatocytes --> bile is then excreted into the bile
canaliculiRL:cholesterol-7a-hydroxylaseWhat are its primary functions? -
digestion and absorption of lipids and fat-soluble vitamins- cholesterol
excretion (body's ONLY means of eliminating cholesterol)- antimicrobial
activity (via membrane disruption) Note that:- bile is mostly recycled in the
ileum
◍ "Butterfly" facial rash and Raynaud phenomenon in a young female.
Answer: Systemic lupus erythematosus
◍ Bilateral hilar adenopathy, uveitis.
Answer: Sarcoidosis (noncaseating granulomas)
◍ Lynch Syndrome.
Answer: formerly HNPCCAutosomal DominantMutation of MMR-MSI
genesMSH2 and MLH1-->MutS and MutL - proximal colon ALWAYS
involved- abdominal pain? melena?- 80% progress to CRC- associated with
endometrial, ovarian and skin cancers
◍ What is Diverticulum?.
Answer: DIVERTICULUM:- blind pouch protruding from gut tract- most
are acquired and termed "false" because they lack or have an attenuated
muscularis externa- most often in the sigmoid colon"True" diverticulum =
all 3 gut wall layers are involved (Meckels)"False" diverticulum = aka
pseudodiverticulum = only mucosa and the submucosa outpouch. Occur
especially where the vasa recta perforate the muscularis externa
◍ 3. Dubin-Johnson Syndrome.
COMPREHENSIVE STUDY GUIDE 2026 FULL
QUESTIONS AND SOLUTIONS GRADED A+
◍ Red urine in the morning, fragile RBCs.
Answer: Paroxysmal nocturnal hemoglobinuria
◍ Which sprue affects the Duodenum more? Which sprue affects the I/J
more?.
Answer: Duodenum: Celiac SprueI/J: Tropical Sprue
◍ Back pain, fever, night sweats.
Answer: Pott disease (vertebral TB)
◍ For the following areas of the digestive tract, please provide the relevant
histological
structures:Esophagus:Stomach:Duodenum:Jejenum:Ileum:Colon:.
Answer: Esophagus: non-keratinized stratified squamous
epitheliumStomach: gastric glands-gastric pits=chief cellsDuodenum: villi
and microvilli serve to increase absorptive surface. Brunner glands (HCO3-
secreting cells of the submucosal and crypts of Lieberkuhn. Jejenum: plicae
circulares and crypts of lieberkuhnIleum: peyer patches and crypts of
lieberkuhnColon: crypts of lieberjuhn but no vili; abundant goblet cells
◍ Chronic PancreatitisWhat is it?Causes?Symptoms?Diagnosis?.
Answer: What is it?:- chronic inflammation, atrophy, calcification of the
pancreas- note that CTFR mutations can cause chronic pancreatic
insufficiencyCauses?- alcohol abuse and idiopathicSymptoms?- steatorrhea,
fat-soluble vitamin deficiency, diabetes mellitusDiagnosis?- amylase/lipase
may or may not be elevated (though are always elevated in acute
pancreatitis)
,◍ What is gastroschisis?Results from a defect in what stage of embryonic gut
development?.
Answer: What is gastroschisis?- extrusion of abdominal contents through
abdominal folds (usually right of umbilicus); NOT covered by
peritoneumResults from a defect in what stage of embryonic gut
development?- defect in lateral fold closure
◍ Infant with cleft lip/palate, microcephaly or holoprosencephaly, polydactyly,
cutis aplasia.
Answer: Patau syndrome (trisomy 13)
◍ Small, irregular red spots on buccal/lingual mucosa with blue-white centers.
Answer: Koplik spots (measles; rubeola virus)
◍ Infant with "cherry-red" spot on macula, hepatosplenomegaly, and
neurodegeneration.
Answer: Niemann-Pick disease (genetic sphingomyelinase deficiency)
◍ Walk through the breakdown/recycling of heme from RBCs to various
products by location:.
Answer: RBC ↓Heme ↓ (heme oxygenase)Biliverdin ↓Unconjugated
bilirubin ↓Bound to albumin ↓ (UDPGT)Conjugated Bilirubin ↓ (gut
bacteria)Urobilinogen ↓excreted as feces (stercobilin--OR--Recycled back
to liver--OR--Excreted in urin as urobilin
◍ What region of the brain controls hunger and fullness?.
Answer: The hypothalamus.The lateral hypothalamic area --> controls
sensations of hunger (ie: stimulates feeding)The ventromedial nucleus of the
hypothalamus (VNH) --> controls sensations of fullness (ie: tells a person to
stop feeding)
◍ Polyuria, renal tubular acidosis type II, growth failure, electrolyte
imbalances, hypophosphatemic rickets.
Answer: Fanconi syndrome (multiple combined dysfunction of the PCT)
◍ Visceral vs Parietal Pain.
, Answer: - differential innervation of the visceral and parietal pleura result in
different types of pain Visceral Pain- transmitted via type C fibers- colicky,
cramping, poorly localized painParietal Pain- parietal peritoneum is
innervated by extensions of the peripheral spinal nerves, which carry the
same types of noxious pain sensations as those overlying the
dermatomes-sharp and localizedThus if the pathologic process progresses
from visceral to the parietal region, the referred pain will become localized,
corresponding to the dermatome overlying the affected organ
◍ What is Zollinger-Ellison syndrome?.
Answer: What is Zollinger-Ellison syndrome?- caused by gastrin secreting
neuroendocrine tumors (gastrinomas) that are most commonly located in the
small intestine or pancreas- gastrin produced by these tumors often leads to
excess gastric acid production resulting in multiple peptic ulcers that can be
located beyond the duodenal bulb (closest part to stomach)Can also have:-
abdominal pain- reflux- diarrhea (due to inactivation of pancreatic/intestinal
exnymes by gastric acid)Diagnosis:- secretin stimulation test: basal and
stimulated gastrin levels- also should undergo testing to exclude MEN 1
◍ Which ligament connects the liver to anterior abdominal wall?.
Answer: Falciform ligament
◍ Muffled heart sounds, distended neck veins, hypotension.
Answer: Beck triad of cardiac tamponade
◍ For the following salivary gland tumors, provide their commonality, and
histological features:Pleomorphic adenomaMucoepidermoid
carcinomaWarthin tumor.
Answer: - salivary gland tumors are most commonly benign in the parotid
gland - tumors in smaller glands are more likely malignant- typically present
as a painless mass/swelling- the presence of facial pain or paralysis suggests
malignant involved of CN VIIPleomorphic adenoma:- benign mixed tumor-
most common salivary gland tumor- made of chondromyxoid stroma and
epithelium - recurs if incompletely excised or ruptured
inraoperativelyMucoepidermoid carcinoma:- most common malignant
, tumor- has mucinous and squamous componentsWarthin tumor:- aka
papillary cystadenoma lymphomatomsum- benign cystic tumor with
germinal centers-SMOKERS
◍ What is bile and how is it made?What makes it?What are its primary
functions?.
Answer: What is bile?bile salts (bile acids +
glycine/taurine)phospholipidscholesterolbilirubinH20ionsWhat makes it?-
hepatocytes --> bile is then excreted into the bile
canaliculiRL:cholesterol-7a-hydroxylaseWhat are its primary functions? -
digestion and absorption of lipids and fat-soluble vitamins- cholesterol
excretion (body's ONLY means of eliminating cholesterol)- antimicrobial
activity (via membrane disruption) Note that:- bile is mostly recycled in the
ileum
◍ "Butterfly" facial rash and Raynaud phenomenon in a young female.
Answer: Systemic lupus erythematosus
◍ Bilateral hilar adenopathy, uveitis.
Answer: Sarcoidosis (noncaseating granulomas)
◍ Lynch Syndrome.
Answer: formerly HNPCCAutosomal DominantMutation of MMR-MSI
genesMSH2 and MLH1-->MutS and MutL - proximal colon ALWAYS
involved- abdominal pain? melena?- 80% progress to CRC- associated with
endometrial, ovarian and skin cancers
◍ What is Diverticulum?.
Answer: DIVERTICULUM:- blind pouch protruding from gut tract- most
are acquired and termed "false" because they lack or have an attenuated
muscularis externa- most often in the sigmoid colon"True" diverticulum =
all 3 gut wall layers are involved (Meckels)"False" diverticulum = aka
pseudodiverticulum = only mucosa and the submucosa outpouch. Occur
especially where the vasa recta perforate the muscularis externa
◍ 3. Dubin-Johnson Syndrome.
