18.1 Skeletal System Flashcards Preview

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Flashcards in 18.1 Skeletal System Deck (72):
1

What, generally, is achondroplasia?

Impaired cartilage proliferation in the growth plate

2

What is the genetic cause of achondroplasia?

Activating mutation in FGFR3, causing inhibition of cartilage growth

3

What is the inheritance pattern of achondroplasia?

Most are sporadic, but if inherited, AD

4

What are the morphological characteristics of achondroplasia? What causes this phenotype?

Short extremities with a normal sized head and chest
-Long bones undergo endochondral bone formation
-Truncal bones undergo intramembranous bone formation

5

What happens to mental function, lifespan, and fertility with achondroplasia?

Not affected

6

What is the intramembranous form of bone creation? What type of bones undergo this?

Bone is produced from a CT matrix

Bones of the skull, chest

7

What is the endochondral form of bone creation? What type of bones undergo this?

Cartilage produced, dies, and calcifies

Long bones

8

What is the defect in osteogenesis imperfecta?

AD defect in collagen type I synthesis

9

What are the clinical features of osteogenesis imperfecta? (3)

-Multiple fractures
-Blue sclera
-Hearing loss

10

Why are the sclera blue with osteogenesis imperfecta?

Exposure of the choroidal veins

11

What is osteopetrosis?

Inherited defect of bone resorption, resulting in abnormally thick, heavy bone that fractures easily

12

What is the pathogenesis of osteopetrosis?

Carbonic anhydrase II mutation results in lack of acidic environment required for resorption of bone

13

What is rxn that carbonic anhydrase catalyzes?

H2O + CO2 = H2CO3

14

What are the radiological characteristics of osteopetrosis?

Abnormally white and dense bones

15

What is Winter's formula? (from sitting in lecture) What is it for?

pCO2 = 1.5(HCO3)+8 +/- 2

Measures compensation

16

What causes the anemia/ thrombocytopenia, and leukopenia with osteopetrosis?

Encroachment of bone on medulla of the bone

17

What causes the vision and hearing impairment of osteopetrosis?

CN impingement 2/2 ossification

18

What causes the hydrocephalus with osteopetrosis?

Ossification of the foramen magnum

19

What causes the acidosis with osteopetrosis?

Carbonic anhydrase deficiency results in a loss of bicarb in the blood, and an inability to excrete acid into the urine

20

What is the treatment for osteopetrosis?

Bone marrow transplant, which causes new and better osteocyte formation

21

What is the defect in rickets/osteomalacia?

Defective mineralization of osteoid 2/2 low levels of vit D

22

What are the four main causes of Vit D deficiency?

-Decreased sun exposure
-Poor diet
-Malabsorption
-Liver failure and renal failure

23

When does rickets usually present?

Less than 1 year old

24

What are the clinical features of rickets? (4)

-Pigeon breast deformity
-Frontal bossing
-Rachitic rosary
-Bowing of legs

25

What is depositied in abnormal places with rickets?

Osteoid

26

What is osteomalacia?

Low vit D in adults results in weak bone with an increased risk for fractures

27

What happen to serum Ca levels with osteomalacia?

Decreased

28

What happen to serum phosphate levels with osteomalacia?

Decreased

29

What happen to serum PTH levels with osteomalacia?

Increased

30

What happen to serum alk phos levels with osteomalacia?

Increased

31

What is the role of alk phos?

Used by osteoblasts to create an alkaline environment for bone to be laid down

32

What diseases is characterized by a loss of trabecular bone mass?

Osteoporosis

33

What are the three factors that determine the peak bone mass?

1. diet
2. exercise
3. Vit D receptor inheritance

34

What is the age that bone mass peaks?

30 years old

35

The risk of osteoporosis is based on what two factors?

Peak bone mass and rate of bone loss thereafter

36

What are the two most common form of osteoporosis?

Senile
Postmenopausal

37

What are the clinical features of osteoporosis?

Bone pain and fractures in weight bearing areas

38

What happens to serum Ca with osteoporosis?

Normal

39

What happens to serum PTH with osteoporosis?

Normal

40

What happens to serum phosphate with osteoporosis?

Normal

41

What happens to serum alk phos with osteoporosis?

Normal

42

How is bone density measured?

DXA scan

43

True or false: there are no abnormal labs with osteoporosis

True

44

What defines osteoporosis vs osteopenia?

Osteopenia = -1 to -2.4 SDs

Osteoporosis = -2.5 and lower

45

What is the treatment for osteoporosis?

Exercise
Vit D
Calcium

46

What is the MOA of bisphosphonates in treating osteoporosis?

Binds to phosphate in bone, and inhibits osteoclastic action (causes apoptosis of osteoclasts)

47

What is the general pathophysiology of Paget's disease of bone?

Imbalance between osteoclast and osteoblast action--first over osteoclast action, followed by osteoblast action that produce crappy bone

48

When does Paget's disease of bone usually present?

Late adulthood (60s)

49

True or false: Paget's disease of bone usually involves the entire skeleton

False--usually one or more, but not entire skeleton

50

What are the three general stages of Paget's disease of bone?

1. Osteoclastic
2. Mixed
3 .Osteoblastic

51

What is the end result of Paget's disease of bone?

Thick, sclerotic bone that fractures easily

52

What are the histological characteristics of Paget's disease of bone?

Tons of eosinophilic bone, with lines that have not been sealed

("Jigsaw puzzle" pattern)

53

Jigsaw puzzle bone = ?

Paget's disease of bone

54

What are the classic features of Paget's disease of bone?

-Increased hat size
-Hearing loss
-Lion-like facies 2/2 bone malformation

55

What lab is classically elevated in Paget's disease of bone?

Alk phos

56

What are the two major drugs that are used to treat Paget's disease of bone?

Calcitonin
Bisphosphonates

57

What causes the high output cardiac failure with Paget's disease of the bone?

Proliferation of AV shunts in bones increases CO

58

What cancer are patients with Paget's disease at increased risk for?

Osteosarcoma (malignant proliferation of osteoblasts)

59

Where does osteomyelitis usually come from?

Hematogenous spread to bone

60

Where in the bone is osteomyelitis usually seen? (kids, adults)

Metaphysis in kids
Epiphysis in adults

61

Is osteomyelitis usually bacterial, fungal, or viral?

Bacterial

62

What is the most common bacteria that causes osteomyelitis?

Staph Aureus

63

What is the most common bacteria that causes osteomyelitis in sickle cell patients?

Salmonella

64

What are the patients that get osteomyelitis 2/2 pseudomonas?

DM and drug abusers

65

What bone does TB classically infect?

Vertebral bodies

66

What are the clinical features of osteomyelitis?

Bone pain with leukocytosis and fever

67

What are the radiological findings of osteomyelitis?

Lytic focus surrounded by sclerosis

68

How can you diagnose osteomyelitis?

Blood cultures

69

What, generally, is avascular (aseptic) necrosis?

ischemic necrosis of the bone and bone marrow

70

What are the causes of avascular (aseptic) necrosis?

-Trauma/fracture
-Steroids
-Sickle cell
-Caisson's disease

71

What are the major complications of avascular necrosis?

Osteoarthritis
Fractures

72

What is Caisson's disease?

"The bends" 2/2 to a reduction in ambient pressure, resulting in the formation of inert gas bubble in tissues, such as the joints, lungs, or brain