Lecture 1

Question 1

What is Bone made up of

Answer 1

Type 1 Collagen

Question 2

What is Bone filled with

Answer 2

Hydroxyapatite

Question 3

Calcium management

Answer 3

Skeleton acts as a reservoir for Ca

Question 4

Types of hormones which offer skeletal management

Answer 4

Sex Steroid, thyroxine, corticosteroids and insulin

Question 5

4 cell types relevant to bone formation and metabolism

Answer 5

Osteoblasts, Osteoclasts, Osteocytes, Osteoprogenitor

Question 6

Osteoblasts position

Answer 6

Bone Surface

Question 7

Osteoblasts Feature

Answer 7

Responsible for laying down bone

Question 8

Osteoclasts Position

Answer 8

Bone surface but low numbers

Question 9

Osteoclasts Features

Answer 9

Move across bone surface reabsorbing bone, multinucleated and contain many mitochondria

Question 10

Osteocytes Position

Answer 10

Cannot divide, most abundant cell in bone, networked by canaliculi

Question 11

Osteocytes Features

Answer 11

Cannot divide, most abundant cell in bone. Networked by canaliculi

Question 12

Three Hormones that play vital roles

Answer 12

Calcitrol, Parathyroid Hormone, Calcitonin

Question 13

Calcitrol

Answer 13

Active form of Vitamin D

Question 14

Role of Calcitrol

Answer 14

Increases blood Ca2+

Question 15

How does Calcitriol increase Ca2+

Answer 15

Increase calcium and phosphate absorption from Intestines
Increasing calcium resorption from bone via indirect osteoclast and direct osteoblast stimulation, decreasing urinary excretion of calcium, by increasing calcium reabsorption by kidneys.

Question 16

How does calcitriol act

Answer 16

Bids to nuclear receptor protein on target tissue and regulate gene expression

Question 17

Parathyroid Hormone role

Answer 17

Increase calcium resorption from bone via indirect osteoclast stimulation
Decreasing urinary excretion of calcium, by increasing calcium resorption by kidneys
Increasing urinary excretion of inorganic phosphate, by decreasing Pi reabsorption by kidneys
Stimulating calcitriol production in the kidneys

Question 18

Role of Calcitonin

Answer 18

Decreases blood Ca2+

Question 19

How does Calcitonin decrease Ca2+

Answer 19

Inhibiting calcium resorption from bone via direct osteoblast stimulation
Increasing urinary excretion of calcium and inorganic phosphate by decreasing resorption by kidneys.

Question 20

Bone Mineral Density

Answer 20

g bone mineral per cm^2

Question 21

Peak Bone Mass

Answer 21

The amount of bony tissue present at the end of the skeletal maturation

Question 22

Lower BMD=

Answer 22

Greater chance/ severity of fracture

Question 23

Bone Density decreases Over time

Answer 23

Oestrogen inhibits bone resorption by reducing osteoblast numbers and activity. A lack if oestrogen allows osteoclast to be more active allowing bone resorption to occur.

Question 24

Osteoporosis

Answer 24

BMD lies 2.5 standard deviations or more below the average value for young healthy person (T- score)

Question 25

Osteopenia

Answer 25

T- Score between -1 to -2.5

Question 26

Typical stress points

Answer 26

Spine, Hip and wrist

Question 27

Why are women more at risk

Answer 27

``` Menopausal effect (Oestrogen) Affected by previous pregnancies Women tend to live longer ```

Question 28

Osteomalacia

Answer 28

softening of the bones, typically through a deficiency of vitamin D or calcium.

Question 29

Mothers at risk due to

Answer 29

- Low Ca intake - Low sun exposure - Long periods of lactation

Question 30

Role of Vitamin D3

Answer 30

Bone growth, Cells of the immune system, pancreas, skin

Question 31

Causes in VD deficiency

Answer 31

Poor diet, inability to absorb/ metabolise vitamin D3, low sunlight exposure

Question 32

Vitamin D3 Formation

Answer 32

1. Sunlight (UV), shining on the skin 2. Inactive form of VD travels to the liver and then the kidneys in a 2 step activation pathway. 3. Active VD can then enter cells and stimulate receptor protein to bind to DNA in the nucleus, acting as a regulator for hundreds of genes.

Question 33

How is VD3 deficiency a risk factor

Answer 33

Risk factor for osteoporosis and osteomalacia

Question 34

Why is sufficient Calcium vital for achieving a high peak bone mass

Answer 34

Peak total body BMD and BMC is attained by the age of 22 yrs and 26 yrs During adolescence around 50 % of peak bone mass is laid down