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Which pancreatic enzymes are secreted in its active form?
α-amylase and lipase
How are inactive pancreatic proenzymes (zygomens) activated?
- 1. Trypsinogen is converted to its active form trypsin by enterokinase/ enteropeptidase, a brush boarder enzyme on duodenal and jejunal mucosa.
- 2. Trypsin activates proenzymes and cleaving of addtional trypsinogen molecules.
What is the action of enterokinase/ enteropeptidase? Where do they work?
Convert trypsinogen to its active form trypsin.
What are the pancreatic proenzymes (zygomens)?
Proteases- includes trypsin, chymotrypsin, elastase, carboxypeptidases
What inhibits activation of trypsinogen?
- Serine peptidase inhibitor kazal type 1 (SPINK1)- impedes activation of trypsinogen and other proenzymes, preventing pancreatic autodigestion.
- Trypsin can serve as its own inhibitor, cleaving other trypsin molecules.
What is the embryological derivative of Rathke pouch (anterior pituitary)?
Where is the anterior pituitary derived from?
- Surface ectoderm
- Rathke's pouch
What is statistical power (1-β)?
- The ability of a study to detect a difference between groups when such a difference truly exists.
- The probability of rejecting the null hypothesis when it is false.
Anti-citrullinated peptide/ proteins are specific for?
Anticentromere autoantibodies are specific for?
Limited scleroderma (CREST syndrome)
Antibodies to double stranded DNA are specific for?
Antinuclear autoantibodies are specific for?
Antibodies to the Fc region of IgG are specific for?
Anti-phospholipid antibodies are specific for?
SLE, anti-phospholipid syndrome.
What is antiphospholipid syndrome?
- ↑Paradoxical PTT
- Recurrent miscarriages (spontaneous abortions)
The presence of which autoantibodies are used to diagnose Rheumatoid arthritis?
- Anti-citrullinated peptide/protein
- Antibodies to IgG Fc region
What is the organism shown below and what disease can it cause?
- Schistosoma hematobium (egg with terminal spine)
- Can lead to squamous cell carcinoma of the bladder (painless hematuria) and pulmonary hypertension
What is the organism and what disease can it cause?
- Schistosoma mansoni (egg with lateral spine)
- Intestinal ulceration
Snails are the host of this infectious organism.
With this infectious organism, cercariae penetrate skin of humans.
Schistosoma. Snails are host.
When do red neurons appear in ischemic brain disease/ stroke?
In ischemic brain disease, what appears 12-48 hours?
- Red neurons
- Eosinophilic neurons. Nissl substance disappears and the nucleus becomes pyknotic (small and deeply basophilic)
What happens at 24-72 hours of ischemic brain injury/ stroke?
Necrosis + Neutrophils
When does necrosis occur in ischemic brain disease?
When do neutrophils appear after ischemic brain disease/ stroke?
What happens on days 3-5 after ischemic brain injury/ stroke?
Macrophages (microglia) appear
When do macrophages (microglia) appear after ischemic brain injury/ stroke?
What side effects are seen with Diphenhydramine?
- H1 blocker
- Antimuscarinic:-pupilllary dilation, dry mouth, urinary retention, constipation (Ach antagonist)
- Anti-alpha adrenergic
Why is it that a patient has infection with H.influenzae despite being immunized?
The strains producing the infection does not produce capsule.
What causes esophageal varices?
Shunting of blood from the portal vein to the left gastric vein→ esophageal vein
What causes Paroxysmal nocturnal hemoglobinuria?
Caused by a mutation in the PIGA gene in population of hematopoietic stem cells that causes absence of the glycosylphosphatidylinositol anchor and associated deficiency of CD55 (Decay-accelerating factor) and CD59 (Mac inhibitory protein) complement inhibitor proteins.
This type of anemia is caused by complement-mediated hemolysis.
Paroxysmal nocturnal hemoglobinuria
This type of anemia acquires its mutation in a hematopoietic stem cell.
Paroxysmal nocturnal hemoglobinuria.
Describe the clinical presentation of Paroxysmal nocturnal hemoglobinuria.
- Coombs - hemolytic aneia
- Aplastic anemia
- Venous thrombosis
- Thrombotic complications (Budd chiari)- due to release of free hemoglobin and other prothrombotic factors.
What is the marker and function of Mac inhibitory protein?
CD59- inhibits complement hemolysis
What is CD59?
- Mac inhibitory protein
- Inhibits complement mediated hemolysis
What is CD55?
- Decay-accelertating factor
- Inhibits complement-mediated hemolysis
What is Factor V Leiden?
- Production of a mutant factor V that is resistant to degradation by activated Protein C.
- MCC of inherited HYPERCOAGULABILITY in whites.
What are the branches of the splenic artery and which is most vulnerable to ischemic injury in the event the splenic artery is blocked?
- The splenic artery gives several branches off to the pancreas and stomach before reaching the spleen.
- 1. Pancreatic artery
- 2. Short gastric arteries- most vulnerable to ischemic injury
- 3. Left gastroepiploic artery- less vulnerable due to strong anastomoses with right gastroepiploic artery
What are the branches of the celiac trunk?
- 1. Common hepatic
- 2. Splenic artery
- 3. Left gastric artery
Where do the short gastic arteries branch from?
- Splenic artery
- They have poor anastomoses if splenic artery is blocked.
Where does the right gastric artery arise from?
- Proper hepatic artery
Where does the gastroduodenal artery arise from?
Common hepatic artery
Where does the right gastroepiploic artery arise from?
- Gastroduodenal artery
- It forms an anastomoses with the left gastroepiploic artery.
Where does the left gastroepiploic artery arise from?
- Splenic artery
- It forms an anastomoses with the right gastroepiploic artery.
What is responsible for testes development (containing Serotoli and Leydig cells)?
SRY gene on Y chromosome codes for testis determining factor which is responsible for gonadal differentiation into testes containing Serotoli and Leydig cells.
What is the function of the SRY gene?
The SRY gene on Y chromosome codes for testis determining factor which promotes development of the testes which houses Leydig and Sertoli cells.
What is the function of Sertoli cells in gonadal development? What happens to genital characteristics if sertoli cells are suppressed in males?
- Sertoli cells secrete Mullerian inhibitory factor which suppress development of paramesonephric ducts. Without sertoli cells or MIF, the paramesonephric ducts go on to develop into the FEMALE INTERNAL GENITALIA (e.g. fallopian tubes, uterus)
- Male has internal male and female genetalia, external male genetalia.
What is the function of leydig cells in gonadal development? What happens to genital characteristics if Leydig cells are suppressed in males?
- Leydig cells secrete testosterone which stimulate the mesonephric (Wolffian) ducts to develop into male internal genitalia (e.g epididymis, vas deferens). Testosterone is converted to dihydrotestosterone which induce development of male external genetalia.
- Underdeveloped male internal and external genetalia.
What is function of H1 histone?
Helps to package the nucleosomes into more compact structures by binding and linking DNA between adjacent nucleosomes.
What is the function of ubiquitin?
Tags proteins for degradation by proteasome.
What is prevalence?
- Measure of the total cases at a particular point in time.
- = # of existing cases/ # of people at risk
Crescent formation on light microscopy is diagnostic for which glomerular disease?
Rapidly progressive (crescentic) glomerulonephritis
What do crescents consist of in RPGN?
- Glomerular parietal cells
- Plasma proteins (e.g C3b)
Which amino acid codes for phenylalanine?
UUU & AUU
What is the action of Menotropin?
Menotropin (human menopausal gonadotropin) acts like FSH, leads to the formation of a dominant ovarian follicle.
What is the use of β-hCG in fertility?
Stimulates LH surge - causes rupture of dominant follicle, leading to ovulation.
What is confounding bias?
Part of the exposure-disease relationship can be explained by another variable.
Matching helps to control which type of bias?
- Confounding bias
- Matching- Use groups that have similar distribution in accordance with the variables (gender, race, age, smoking status)
Describe the pathogenesis and clinical presentation of a gallstone ileus.
- 1. Gallstone obstructs cystic duct
- 2. This causes a fistula to be created between the gallbladder and small intestine.
- 3. Gallstone passes through the fistula and becomes lodged in ileocecal valve.
- 4. Intestinal gas backs up into the gallbladder and biliary tree.
Describe the structure of cilia.
- Cilia is composed of 2 central microtubules, surrounded by 9 microtubule doublets.
- Each microtuble doublet is connected to the adjacent doublet by dyenin arms.
- Dyenin arms contain the dyenin ATPase that generates energy for the dyenin arms to slide past each other, producing ciliary movement.
What complications can arise from Kartagener syndrome?
- Male and female infertility- immotile sperm and dysfunctional fallopian tube cilia
- ↑risk of ectopic pregnancy
- Bronchiectasis- enlargement of lung airways
- Recurrent sinusitis
- Situs inversus (e.g dextrocardia)- Cardiac point of maximal impulse is on the RIGHT
What causes Hyper IgM syndrome?
Defective CD40L/ CD154 on CD4+ T cell → B cell cant undergo class switching from IgM
What causes a persistent truncus arteriosus?
Caused by the abnormal neural crest cell migration through the truncus arteriosus and bulbus cordis to separate the aorta and pulmonary artery.
What causes Transposition of the great vessels?
Failure of the aorticopulmonary septum to spiral due to abnormal migration of neural crest cells.
What causes Tetraology of Fallot?
- Abnormal migration of neural crest cells through the truncus arteriosus and bulbus cordis to separate the aorta and pulmonary artery.
- Results in anterior displacement of the infundibular septum.
Which heart defects are caused by the abnormal migration of neural crest cells?
- Tetralogy of Fallot
- Transposition of the great vessels
- Truncus arteriosus
What does an endocardial cushion defect results in?
- Failure of the atria and ventricles to separate.
- Defect in atrioventricular septum.
Where are thyroid hormone receptors located?
Inside the nucleus
Describe the splitting of an Atrial Septal Defect.
- Wide, fixed spliiting of S2.
- ASD creates a left to right shunt (because of higher pressure in the left atrium).
- This results in increased blood flow through the pulmonary artery, delaying pulmonary closure.
What causes Eisenmenger syndrome?
Uncorrected left-to-right shunt (VDS, ASD, PDA)
causes such ↑ pulmonary blood flow through the pulmonary atery, which results in pathologic remodeling of the vasculature (pulmonary sclerosis).
- The hypertrophied Right ventricle occurs to compensate and the shunt becomes right-to-left.
- Causes late cyanosis, clubbing and polycythemia.
Describe the symptoms of heroin withdrawal.
- Dilated pupils
- Hyperactive bowel sounds/ stomach cramps
Describe the clinical presentation of myasthenia gravis.
- Ptosis- drooping of eyelid
- Eye weakness- tired eyes
- Muscle weakness worsens during course of the day
- Decreased force of muscle contraction with repetitive stimulation
- Associated with thymomma or thymic hyperplasia- presents as ANTERIOR MEDIASTINAL MASS
Where does lymph from the head drain into?
Cervical lymph node
Where does lymph from the esophagus drain into?
Cervical lymph node
Where does lymph from the lungs drain to?
Hiliar lymph node
Where does lymph from the trachea drain into?
Mediastinal lymph node
Where does lymph from the esophagus drain to?
Mediastinal lymph node
Where does lymph from the testes drain into?
Para-aortic lymph node
Where does lymph from the ovaries drain into?
Para-aortic lymph node
Where does lymph from the kidneys drain into?
Para-aortic lymph node
Where does lymph from the uterus drain into?
Para-aortic lymph node
Wher does the popliteal lymph node drain?
- Dorsolateral foot
- Posterior calf
Where does the axillary lymph node drain?
- Upper limb, breast, skin above umbilicus
Where does the celiac lymph node drain?
- Liver, stomach, spleen, pancreas, upper duodenum
What does the superior mesenteric lymph node drain?
- Lower duodenum, jejunum, ileum, colon to splenic flexure
Where does the inferior mesenteric lymph node drain?
- Colon from splenic flexure to upper rectum
Where does the internal iliac lymph node drain?
Where does the superficial inguinal lymph node drain?
- Anal canal (below pectinate line)
- Skin below umbilicus (except popliteal territory)
Where does lymph from the scrotum drain into?
Superficial inguinal lymph node
Where does lymph from the bladder drain into?
Where does lymph from the prostate drain into?
Where does lymph from the anal canal (above the pectinate line drain into?
Where does lymph from the anal canal (below the pectinate line) drain into?
Label the image below
- A- I band
- B- A band
- C- H band
- D- I band
- E- Z line
- F- M lineG- Z line
At this region of the sacomere, myosin filaments are bound to structural proteins.
At this region of the sacomere, actin filaments are bound to structural proteins.
D&F: Z line
At this region of the sacomere, actin does not overlap with myosin.
A: I band
At this region of the sacomere, myosin does not overlap with actin
C- H band
Which bands decrease in size during contraction?
I-band and H-band
This band extends over the entire region of the thick myosin filaments.
B- A band
This band does not change size during contraction.
B- A band
What is sampling bias?
- Non-random sampling of a populationA common example is that severely ill patients are the most likely to enroll in cancer trials, leading to results that are not applicable to patients with less advanced cancers.
What is Allocation bias?
- Can result from the way treatment control groups are assembled.
- It may occur if subjects are assigned to the study groups of a clinical trial in a non-random fashion.
- For instance, in a study comparing oral NSAIDs and corticosteroid injects for the tx of osteoarthritis, obese patients may be preferentially assigned to corticosteroid group.
What is detection bias?
- Refers to the fact that a risk factor itself may lead to extensive diagnostic investigation and increase the probability that a disease is identified.
- For instance patients who smoke may undergo increased imaging surveillance, due to their smoking status, which would detect more cases of cancer in general.
What is Referral (admission rate) bias?
- Occurs when the case and control populations differ due to admission or referral practices.
- For instance, a study involving cancer risk factors performed at a hospital specializing in cancer research may enroll cases referred from all over the nation. However, hospitalized control subjects without cancer may come from only the local area.