USMLE Pathology

Question 1

PaO2 and SaO2 levels in CO poisoning?

Answer 1

PaO2 normal, SaO2 decreased

Question 2

What cells can only undergo hypertrophy?

Answer 2

Skeletal muscle, heart, neurons

Question 3

What cellular functions stop working with hypoxia?

Answer 3

Na/K pumps = swelling, Ca pumps = Enzyme activation, Aerobic to anaerobic glycolysis = lactic acidosis, lowers pH

Question 4

Where is the electron transport chain located?

Answer 4

Inner mitochondrial membrane

Question 5

What are the three stages of cell death?

Answer 5

Pyknosis (shrinks down), karyorrhexis (nucleus breaks down), karyolysis (broken down)

Question 6

When do you get a red infarct?

Answer 6

When blood reenters an infarcted area (of loosely connected tissue)

Question 7

Why is necrosis in the brain liquefactive?

Answer 7

Because microglial cell enzymes destroy everything

Question 8

What situations do you see liquefactive necrosis in?

Answer 8

Brain ischemia, abscess, pancreatitis

Question 9

How do you distinguish dystrophic calcification from metastatic calcification?

Answer 9

Dystrophic = normal Ca PO4 in serum, will be elevated in metastatic

Question 10

What are the three apoptotic pathways?

Answer 10

1) Intrinsic mitochondrial pathway (Bcl2, cytC)
2) Extrinsic receptor-ligant pathway (FasL, TNF)
3) Cytotoxic T cell pathway (perforin, granzymes)

Question 11

Delayed separation of umbilical cord?

Answer 11

Leukocyte adhesion deficiency

Question 12

What factors mediate pain?

Answer 12

PGE2 and bradykinin

Question 13

What factors mediate inflammation

Answer 13

Mast cells, arachidonic acid, TLRs, complement, Hageman’s factor

Question 14

What are mast cells activated by?

Answer 14

Tissue trauma, C3a, C5a, and cross linking by IgE

Question 15

What factors are responsible for neutrophil chemotaxis?

Answer 15

LTB4, C5a, IL-8, bacterial products

Question 16

What is an important example of TLRs in action?

Answer 16

CD14 on macrophages binds LPS on G-ve bacteria to activate NfKB

Question 17

Features of Chediak Higashi syndrome?

Answer 17

Dysfunctional primary hemostasis
Albinism
Peripheral neuropathy
Infections (pyogenic)
Neutropenia
Giant granules in leukocytes

Question 18

Recurrent infections by catalase positive organisms?

Answer 18

Chronic granulomatous disease

Question 19

How do macrophages continue acute inflamm?

Answer 19

IL-8

Question 20

How do macrophages initiate resolution and healing?

Answer 20

IL-10, TGF-B

Question 21

How are CD4 T cells activated?

Answer 21

TCR to MHC II with antigen and B7 to CD28 on T cell

Question 22

How are CD8 T cells activated

Answer 22

TCR to MHC I with antigen and IL-2 from TH1 CD4+ helper cells

Question 23

What cytokines are produced by CD4+ Th1 cells?

Answer 23

Helps CD8 T cells

IL-2 - promotes T cell proliferation, IFN-gamma: activates macrophages

Question 24

What cytokines are produced by CD4+ Th2 cells?

Answer 24

Helps B cells
IL-4 - switch to IgG, IgE
IL-5 eosinophils and switch to IgA
IL-10 inhibits Th1 subtype

Question 25

How are B cells activated independent of T cells?

Answer 25

BCR binds to antigen and becomes plasma cell expressing IgM, IgD

Question 26

How are B cells activated by T cells?

Answer 26

B cell presents antigen on MHC II to CD4+ Th2 cells, CD40 on B cell binds CD40L on T cell --> IL4/IL5 for class switching

Question 27

What are the key cells in granulomas?

Answer 27

Epithelioid histiocytes (surrounded by giant cells and rim of lymphocytes)

Question 28

How are granulomas activated?

Answer 28

Macrophage presents antigen on MHC II to T helper cell and secretes IL-12 to turn it into TH1 cell. TH1 cell secretes IFN-gamma to turn macrophages into EH cells

Question 29

What is the cause of DiGeorge syndrome?

Answer 29

Microdeletion 22q11

Question 30

High yield cause of SCID?

Answer 30

Adenosine deaminase deficiency (builds up in lymphocytes, kills it)

Question 31

Chronic candida, adrenal failure, hypoparathyroidism. Dx?

Answer 31

Autoimmune polyendocrine syndrome (AIRE deficiency)

Question 32

What receptors are expressed on Treg cells?

Answer 32

CD4, CD25 (IL2-R), FOXP3

Question 33

How do Tregs do their work?

Answer 33

Compete with B7 with CTLA4 and release IL-10/TGF-B to shut down MHC II, DC, macrophages, and B7

Question 34

How does peripheral tolerance work?

Answer 34

Induces anergy if TCR binds MHC II without B7/CD-28 (absent in non-inflammatory states), or self expresses Fas to apoptose

Question 35

Features of IPEX syndrome?

Answer 35

Immune dysfn, polyendocrinopathy, enteropathy, x-linked

Question 36

What causes hyper IgM syndrome?

Answer 36

CD40/CD40L mutation = only IgMs produced, susceptible to pyogenic infections

Question 37

What risks associated with common variable immunodeficiency?

Answer 37

Bacterial, giardia, enterovirus infxns + risk of AI disease/lymphoma

Question 38

What makes up granulation tissue?

Answer 38

Blood vessels, fibroblasts (for T3 collagen), and myofibroblasts

Question 39

T1 collagen?

Answer 39

Bone

Question 40

T2 collagen?

Answer 40

Cartilage

Question 41

T3 collagen?

Answer 41

Granulation tissue, embryonic tissue, blood vessels

Question 42

T4 collagen?

Answer 42

Basement membrance

Question 43

TGF-alpha

Answer 43

Epithelium and fibroblast GF

Question 44

TGF-beta

Answer 44

Fibroblast GF and anti inflammatory

Question 45

PDGF

Answer 45

Endothelium, smooth muscle, fibroblast GF

Question 46

FGF

Answer 46

Angiogenesis and skeletal development

Question 47

VEGF

Answer 47

Angiogenesis

Question 48

What kind of collagen is seen in keloid scars?

Answer 48

T3 collagen

Question 49

Aflatoxins

Answer 49

HCC, in Africa and stored grains

Question 50

Alkylating agents

Answer 50

Lymphoma, leukemia

Question 51

Alcohol

Answer 51

SqCC of oropharynx & upper esophagus, HCC, pancreatic cancer

Question 52

Arsenic

Answer 52

SqCC of skin, lung cancer, angiosarcoma of liver

Question 53

Nitrosamine

Answer 53

Intestinal type stomach cancer

Question 54

Vinyl chloride

Answer 54

Angiosarcoma of liver

Question 55

EBV cancer associations?

Answer 55

Nasopharyngeal cancer, Burkitt lymphoma, CNS in AIDS

Question 56

HHV 8

Answer 56

Kaposi's sarcoma in E. European males, AIDS, transplant

Question 57

HTLV-1

Answer 57

ATLL

Question 58

Ionizing

Answer 58

AML, CML, Papillary thyroid carcinoma

Question 59

Ret

Answer 59

Associated with medullary carcinoma of thyroid in MEN2A/2B

Question 60

PDFG-B overexpression

Answer 60

Astrocytoma

Question 61

What is ABL responsible for?

Answer 61

9:22 translocation seen in CML and adult B-ALL

Question 62

What are you at risk of with germline mutation of Rb?

Answer 62

Bilateral retinoblastomas and osteosarcoma