Block 3

Question 1

How can the lunate bone be identified on a hand X-ray?

Answer 1

It’s the more medial of the 2 carpal bones that articulate with the radius. it lies immediately medial to the scaphoid bone

Question 2

What is the most common cause of hair loss, demonstrating polygenic inheritance with variable penetrance?

Answer 2

Androgenetic alopecia (male patterned baldness)

Question 3

What is RF?

Answer 3

Rheumatoid factor is an IgM antibody specific for the Fc component of self IgG. It binds IgG and forms immune complexes that circulate in the serum.

Immune complexes activate complement in those locations –> chronic inflammation

Question 4

Describe the role of CD4+ cells in rheumatoid arthritis.

Answer 4

CD4+ T-helper cells become activated by the cartilage proteins and release cytokines that mediate chronic inflammation.

CD4+ cells also induce B-cells to become rheumatoid factor-synthesizing plasma cells.

Question 5

What line does actin bind to? What line is myosin anchored to?

Answer 5

Actin (thin myofilament) binds to Z line. Z-line lies in the center of the lucent region (I band).

Myosin is anchored to M line which is centered on the dark H-band.

“An Interesting Zoo Must Have Mammals”

Question 6

what kind of receptors does myasthenia gravis involve?

Answer 6

nicotinic receptors

Question 7

muscarinic overstimulation from myasthenia gravis treatment can be ameliorated by use of what?

Answer 7

an antimuscarinic agent like scopolamine

Question 8

a form of multinucleated giant cell that plays a role in granulomatous inflammation

Answer 8

Langhans cell

Question 9

dendritic cells found in the skin that act as professional antigen presenting cells.

these cells are derived from the myeloid cell line and they possess characteristic racquet-shaped intracytoplasmic granules known as Birbeck granules

Answer 9

Langerhans cells

Question 10

what are Birbeck granules?

Answer 10

characteristic racquet-shaped intracytoplasmic granules in Langerhans cell

Question 11

an epidermal accumulation of edematous fluid in the intracellular spaces seen with acute eczematous dermatitis (contact dermatitis).

CD4+ T cell response

Answer 11

spongiosis

Question 12

what receptor acts to initiate the extrinsic pathway of apoptosis?

Answer 12

Fas receptor

mutations in Fas increase risk of autoimmune disorders like SLE

Question 13

what is the origin and insertion of the sternocleidomastoid?

Answer 13

origin: medial clavicle and manubrium
insertion: mastoid process of the skull

Question 14

what does the common peroneal nerve do?

Answer 14

dorsiflexion, eversion, sensation over the dorsum of the foot

Question 15

how is nafcillin resistance mediated?

Answer 15

by alterations in PBPs

Question 16

what is the embryologic derivative of melanocytes?

Answer 16

neural crest cells

Question 17

what causes the hypercalcemia associated with squamous cell lung cancer and several other tumors?

Answer 17

the overproduction of parathyroid hormone-related peptide (humoral hypercalcemia of malignancy”

Question 18

what do enzyme deficiencies of the early steps in porphyrin synthesis (prophobilogen deaminase, ALA dehydratase) cause?

Answer 18

neuropsychiatric manifestations without photosensitivity

Question 19

what do late step enzyme derangements in the synthesis of porphyrin (uroporphyrinogen decarboxylase) cause?

Answer 19

porphyria cutanea tarda

photosensitivity

Question 20

“housemaid’s knee,” common in roofers, plumbers, and carpet layers

knee pain, erythema, swelling, inability to kneel on affected side

Answer 20

prepatellar bursitis

Question 21

what enzyme is responsible for the production of the activated ribose necessary for de novo synthesis of purine and pyrimidine nucleotides

increased activity will lead to more purines, increasing the RISK OF GOUT

Answer 21

PRPP synthetase

Question 22

what bacteria causes a late-onset food poisoning characterized by a transient watery diarrhea and gastroenteritis caused by toxin formed when large quantities of spores are injested?

Answer 22

C. perfringens

Question 23

When is glycogen phosphorylase active and what does it do?

Answer 23

Glycogen phosphorylase is active when phosphorylated by glycogen phosphrylase kinase.

It breaks down glycogen

Question 24

How is glycogen phosphorylase inactivated?

Answer 24

Protein phosphatase dephosphorylates glycogen phosphorylase, making it inactive

Question 25

how is phosphorylase kinase activated?

Answer 25

it’s phosphorylated by PKA in response to increased cAMP through binding of epinephrine (in muscle) and glucagon (in liver) to Gs-protein coupled receptors

increased Calcium in cytosol activates phosphorylase kinase which activates glycogen phosphorylase

Question 26

Foreign bodies, like retained sutures, can elicit what kind of immunological response?

Answer 26

granulomatous response

Question 27

what does etanercept do?

Answer 27

reduces the biological activity of TNF-a by acting as a decoy receptor.

Question 28

what is the suffix for kinase inhibitors?

Answer 28

kinase inhibitors = -nib

Question 29

plasma protein that binds free Hb to prevent its renal excretion

Answer 29

haptoglobin

haptoglobin levels decrease with hemolysis (sickle cell)

Question 30

what virus causes Rubella?

Answer 30

togavirus

Question 31

a maculopapular rash that begins on the face and spreads to the trunk and extremities along with POSTAURICULAR LYMPHADENOPATHY is suggestive of…

Answer 31

Rubella

Question 32

Why should PPD skin tests be performed before administration of TNF-a inhibitors?

Answer 32

TNF-a inhibitors used to treat RA could reactivate latent TB

Question 33

Name 3 causes of acne

Answer 33

• after conversion to DHT, androgens promote both follicular epidermal hyperproliferation and ecessive sebum production –> causing acne
• epidermal growth factor recepotr inhibitors
• lithium

Question 34

a common side effect of most diuretics other than the potassium-sparing class

Answer 34

hypokalemic metabolic alkalosis

Question 35

what electrolyte disorder manifests with muscle weakness and cramping?

Answer 35

hypokalemia

Question 36

what is a xanthelasma?

Answer 36

a cutaneous lesion commonly found on the eyelid that contains lipid-laden macrophages (foam cells)

these papules are typically yellow due to the location of the foam cells in the superficial dermis

associated with hyperlipidemia

Question 37

what skin finding can chronic cholestatic processes including obstructive biliary lesions and primary biliary cirrhosis cause?

Answer 37

subsequent hypercholesterolemia –> formation of xanthelasmas