UWORLD ROUND 1 Flashcards
by what week of gestation do neural crest cells reach the proximal colon and rectum?
8th week-proximal colon
12th week - rectum
The arrest of migration of neural crest cells during gestation causes which disease?
Hirschsprung disease (rectum is always involved)
Sx of Hirschsprung disease?
- failure to pass meconium within 48 hrs of birth
- sx of intestinal obstruction (bilious vomiting & abd. distention)
- bowel is filled with stool but the rectum is empty
- anal sphincter tone increased
- rectal biopsy reveals an anganglionic segment of bowel
poststreptococcal glomerulonephritis is caused by what type of hypersensitivity?
nephritic syndrome
type III (immune-complex-mediated) hypersensitivity
-deposition of antibody-antigen complexes (IgG, IgM, C3)
pleiotropy
multiple phenotypic manifestations result from a single genetic mutation
local heterogeneity
ability of one disease or trait to be caused mutations in multiple different genes. Ex: familial hypercholesteremia, which can be caused by different mutations affecting cholesterol metabolism (LDL receptor, apo B-100)
alpha 1 receptor:
target organ
effect of stimulation
examples
target organ: peripheral vasculature, bladder, eye
effect: inc. BP (esp. systolic), contraction of internal urethral sphincter, mydriasis (contraction of pupillary dilator muscle)
Ex: Epi, NE, phenylephrine
beta 1 receptor:
target organ
effect of stimulation
examples
target organ: heart
effect: inc. HR, contractility & conductance
Ex: Epi, Dopamine, Dobutamine, Isoproterenol
Beta 2 receptor:
target organ
effect of stimulation
examples
target: peripheral vasculature (smooth muscle), bronchi, uterus
effect: vasodilation, dec. BP (esp. diastolic), bronchodilation, uterus relaxation (tocolysis)
Ex: Isoproterenol, Terbutaline
nonselective beta agonist MOA
inc. myocardial contractility and dec. systemic vascular resistance
Ex: isoproterenol
virulence factor of strep. pneumo
polysaccharide capsule that inhibits opsonization and phagocytosis
MOA of fluorouracil
inhibits thymidylate synthase
clostridium perfringens alpha toxin affects cells and facilitates the spread of gas gangrene via what MOA
splitting lecithin to phosphorylcholine and diglyceride
surface ectoderm derivatives
- anterior pituitary (rathke pouch)
- lens & cornea
- inner ear sensory organs, olfactory epithelium
- nasal & oral epithelial linings, salivary glands
- epidermis, sweat and mammary glands
neural tube (from ectoderm) derivatives
- brain & spinal cord
- post. pituitary, pineal gland
- retina
neural crest (from ectoderm) derivatives
- neural ganglia, adrenal medulla
- schwann cells; pia & arachnoid mater
- aorticopulmonary septum & endocardial cushions
- branchial arches (bones & cartilage)
- skull bones
- melanocytes
mesoderm derivatives
- Muscles (skeletal, cardiac, smooth)
- CT, bone, cartilage
- Serosal linings (peritoneum)
- Cardiovascular & lymphtic system
- Spleen & hemopoietic cells
- Kidney & ureters, internal genitalia
- Adrenal cortex
Endoderm derivatives
- GI tract, liver, pancreas
- Lungs
- Thymus, parathyroid, thyroid follicular cells
- Middle ear epithelium
- Bladder & urethra
- Parafollicular (C) cells
gap junction proteins
proteins: connexins
upregulated by estrogen immediately prior to delivery
tight junction proteins
claudins, occludin
adherens junction proteins
cadherins
desmosome proteins
cadherins (desmogleins, desmoplakin)
hemidesmosome proteins
integrins
what is the diagnostic feature of infectious mononucleosis
reactive lymphocytes:
large, scalloped and have abundant cytoplasm.
They contain cytotoxic granules composed of perforins (create holes in the infected cell’s membrane) and granzymes (enter the cytoplasm of infected cells and trigger cell death), which are released in response to foreign antigens on the surface of MHC I receptors (cytotoxic T cells) of infected host cells
ventral pancreatic bud contributes to which structures?
main pancreatic duct and uncinate process
the dorsal pancreatic bud contributes to which structures?
body, tail, isthmus and accessory pancreatic duct
what embryonic structure composes the pancreatic head?
both ventral and dorsal pancreatic buds
chromaffin cells:
location & function
modified neuroendocrine cells derived from the neural crest and located in the adrenal medulla
-they are stimulated by acetylcholine released by sympathetic preganglionic neurons and secrete catecholamines (80% Epi, 20% NE) directly into the bloodstream to amplify SNS activity
role of cortisol in catecholamine synthesis?
cortisol produced in response to ACTH increases the activity of the adrenal medullary enzyme phenylethanolamine N-methyltransferase, which catalyzes the conversion of NE to Epi
site of thoracentesis
- below 6th rib midclavicular
- below 8th rib midaxillary
- below 10th rib paraverterbrally
**insertion of needle below the 9th rib increases the risk of penetrating abdominal structures
GPCR receptors on pancreatic beta cells:
- M3 - Gq - inc. insulin secretion
- Glucagon - Gs/Gq - inc. insulin secretion
- beta 2 adrenergic & Glucagon like peptide 1- Gs - inc. insulin secretion
**alpha 2 adrenergic, somatostatin 2 - Gi - decrease insulin secretion
sympathetic stimulation’s effect on insulin secretion
pancreatic beta cells contain both alpha 2 and beta 2 receptors, which exert opposite effects. However, alpha 2 mediated inhibitory effect is predominant, causing SNS to lead to overall inhibition of insulin secretion
thayer martin medium
used to identify pathogenic Neisseria organisms:
chocolate sheep blood agar infused with vanocmyocin to inhibit gram positive bacteria, colistin and trimethoprim to inhibit gram negative bacteria and nystatin to inhibit yeast
function of glucagon like peptide 1 (GLP-1)
regulates glucose by slowing gastric emptying, suppressing glucagon secretion and increasing glucose-dependent insulin release
which drugs decrease breakdown of GLP-1?
Dipeptidyl peptidase-4 inhibitors (sitagliptin, saxagliptin) decrease breakdown of GLP-1 and improve glycemic control in patients with type II diabetes
*low risk of hypoglycemia
mechanism of penicillin resistance:
- beta lactamase, ESBL
- mutated penicillin binding proteins
- mutated porin protein
mechanism of vancomycin resistance:
- mutated peptidoglycan cell wall
- impaired influx/increased efflux
mechanisms of quinolone resistance:
- mutated DNA gyrase
- impaired influx/increased efflux
mechanism of aminoglycosides resistance:
- aminoglycoside-modifying enzymes
- mutated ribosomal subunit protein
- mutated porin protein
mechanism of tetracycline resistance:
- impaired influx/increased efflux
- inactivated enzyme
mechanism of rifamycin resistance:
-mutated RNA polymerase
A stepmother treats a child she resents with excessive nurturing and overprotection
reaction formation - replacing a warded-off idea or feeling with an emphasis on its opposite
