Bone and new markers Flashcards Preview

Clinical Pathology > Bone and new markers > Flashcards

Flashcards in Bone and new markers Deck (55)
Loading flashcards...
1

What part of the bone is corticoid bone?

Hard, out layer

2

What part of the bone is the trabecular bone?

Spongy, inner layer

3

What do osteoblasts do?

Secrete bone

4

What do osteoclasts do?

absorb bone

5

What is the function of the trabecular bone?

Bone marrow -
-Haemopoesis

6

What is the extracellular part of bone composed of?

Inorganic matrix - hydroxyapatite, minerals e.g. calcium, phosphate

Organic matrix - collagen

7

What is bone before it is mineralised?

Osteoid

8

What mineralises bone?

Hydroxyapatite
(calcium-phosphate, hydroxide salt)

9

Why is bone considered a dynamic tissue?

Constantly being remodelling

High vascular

Metabolically active

Osteoblasts produce and secrete metric and help with mineralisation

Osteoclasts reabsorb (both clasts/blast actions = linked)

10

What do osteoblasts do?

Make osteoid (non-mineralised organic matrix - mainly collagen)

Make hormones (osteocalcin), matrix proteins and alkaline phosphatase

11

What are osteoblasts called when buried underneath/trapped within matrix?

Osteocytes

12

What enzymes do osteocytes produce?

Tartrate resistant acid phosphatase (TRAP)

Cathespin K

13

What main hormone is osteoclasts regulated by?

PTH

14

What ligands/proteins helps with osteoclast maturation and activity

RANK (produced by osteoblasts)

Osteoprotegrin

15

What are the function of osteocytes?

Maintain bone matrix turnover

16

What is the bone remodelling process?

Osteocyte -> reabsorption pit -> osteoblast -> produce osteoids -> mineralisation (hydroxyapatite) -> osteocyte

17

Why is reduced bone mass related to menopause?

Loss of oestrogen

18

What also happens as you get older (i.e. osteoclastic - osteoblastic activity)

Osteoclastic activity increases - balance tipped to bone reabsorption

19

What diagnostic test is used to investigate bone gross structure?

X-rays

20

What investigative technique is used to assess bone mass? (I.e. calcium levels)

DEXA scan

21

What biomarkers indicate bone formation (i.e. pro-osteoblastic activity)

Osteocalcin

Pro collagen type I phosphatase (P1NP)

Alkaline phosphatase

22

What markers could be used for bone reabsorption

Cross linked telopeptides of type 1 collagen (CTX/NTX)

23

What markers could be used for osteoclastic activity? (i.e. enzymes)

TARP (tartrate acted resistant phosphatase)

Cathespin K

24

What produces alkaline phosphatase?

Osteoblasts - indicator of bone remodelling

25

When is high levels of all pos observed?

-Fractures
-Hyperthyroidism
-Pagets disease of bone

26

What is pro collagen type I phosphatase an indicator of? what is it a particularly good marker?

Indicates osteoblastic activity

Good because it is a very stable marker - no diurnal variation/no affected by food intake

27

What does cross linked telopeptides of Type I collagen indicate? What can their use be problematic?

Indicates bone reabsorption e.g. adolescence, menopause, hyperthyroidism

However diurnal variation/affected by food intake

28

What are the problems with using bone markers?

Not disease specific

Not specific - type I collagen which is widely distributed in body

Intra-individual variability

29

What is a DEXA scan used to determine? What do the T scores indicate

Bone mass/density

T score - number of SD's away

normal = -1+
Osteopenia = -1 - -2.5
Osteoporosis =

30

What are the risk factors for osteoporosis?

Age
Early menopause
Malnutrition
Alcohol/smoking
Steroids

Decks in Clinical Pathology Class (50):