NBME 16 Flashcards
(112 cards)
Cystic fibrosis is due to a defect in what
protein structure of the ATP gated Cl- channel
What is the cellular process for muscle atrophy
polyubiquitination
Our body goes through arteriolar vasoconstriction to do what?
MAMMALS IN A COLD ENVIRONMENT
Vasoconstriction also occurs in superficial blood vessels of warm-blooded animals when their ambient environment is cold; this process diverts the flow of heated blood to the center of the animal, preventing the loss of heat.
What does central venous pressure represent?
pressure in the thoracic vena cava near the right atrium (therefore CVP and right atrial pressure are essentially the same)
- it is a major determinant of the filling pressure and therefore the preload of the right ventricle, which regulates stroke volume
What causes hemochromatosis?
- recessive mutation HFE gene C282Y which is a point missense mutation changing cysteine to tyrosine
- this results in abnormal iron sensing and increase intestinal absorption
- can also be secondary to chronic transfusion therapy like in beta-thalassemia major
A 45 year old man is admitted because of CHF. 2 relatives died of dilated cardiopathy and cirrhosis. PE shows hyperpigmentation and elevated glucose. What is the cause?
hemochromatosis
Presents in patients after age 40 when total body iron >20g. Women show signs later because they lose iron through menstruation. Classic triad is: DIABETES, CIRRHOSIS, SKIN PIGMENTATION (BRONZE DIABETES)
In addition to cirrhosis, diabetes, skin pigmentation, what can patients with hemochromatosis present with?
- classically restrictive cardiomyopathy but also dilated cardiomyopathy (reversible)
- hypogonadism
- arthropathy (calcium pyrophosphate deposition especially in MCP joints)
- HCC is common cause of death
How is hemochromatosis treated?
- repeated phlebotomy
- chelation with deferasirox, deferoxamine, oral deferiprone
What are neuroendocrine tumors?
Group of neoplasms originating from Kulchitsky and enterochromaffin-like cells.
Occur in various organs: 1. thyroid: medullary carcinoma 2. Lungs: small cell carcinoma 3. pancreas: islet cell tumor 4. adrenals: pheochromocytoma
Cells contain amine precursor uptake decarboxylase (APUD) and
secrete different hormones (eg, 5-HIAA, neuron-specific enolase [NSE], chromogranin A
What is the MOA of hydralazine?
increased cGMP to cuase smooth muscle relaxation
Vasodilates arterioles > veins; afterload reduction
What is hydralazine used for?
- Severe hypertension (particularly acute), 2. HF (with organic nitrate).
Safe to use during pregnancy.
Frequently coadministered with a β-blocker to prevent reflex tachycardia
What are the SE of hydralazine?
Compensatory tachycardia (contraindicated in angina/CAD)
fluid retention, headache, angina.
Lupus-like syndrome.
Non-selective α-blockers
- phenoxybenzamine
2. Phentolamine
α-1-selective-blockers
prazosin
terazosin
doxazosin
tamsulosin
- zosin ending
α-2-selective-blockers
mirtazapine
β1-selective blockers [β1>β2]
acebutolol (partial agonist) atenolol betaxolol bisoprolol esmolol metoprolol
- SELECTIVE ANTAGONIST MOSTLY GO FROM A to M
nonselective β blockers [β1=β2]
nadolol
pindolol (partial agonist)
propranolol
timolol
Nonselective α1 and β-blocker
carvedilol
labetalol
MOA of Nebivolol
cardioselective β1-blocking with stimulating β3- receptors (activate NOS synthase in vasculature and decreases SVR)
What is cystic hygroma associated with?
Turner syndrome.
What is tracheomalacia?
Tracheal cartilage is soft so that the trachea partially collapses when the person breathes out
can be congenital, compression from vascular rings or acquired during infection
What does the SMA supply
Distal duodenum to proximal 2/3 of transverse
colon
[midgut]
What does the celiac artery supply
Pharynx (vagus nerve only) and lower esophagus
(celiac artery only) to proximal duodenum;
liver, gallbladder, pancreas, spleen (mesoderm)
What does the IMA supply
Distal 1/3 of transverse colon to upper portion of
rectum