Bone and Cartilage

Question 1

give components of cartilage

Answer 1

chondrocytes that produce extracellular matrix
large ratio of glycosaminoglycans to type 2 collagen in matrix allows for diffusion of nutrients between chondrocytes and blood vessels

the extracellular fluid has hyaluronic acid that makes it strong and pliable.

hyaluronate proteoglycan aggregates are interwoven with network of collagen fibres

Hyaluronate proteoglycan aggregates = proteoglycan monomers (protein + glycosaminoglycans) + hyaluronic acid

Question 2

what are the components of hyalin cartilage matrix? and what produced the matrix

Answer 2

chondrocytes secrete the matrix

proteoglycans
hyaluronic acid
type 2 collagen

Question 3

what are the two layers in hyaline cartilage and what types of growth occur at both?

Answer 3

perichondrium - appositional growth from developing chondrocytes

extracellular matrix - chondrocytes = interstitial growth

Question 4

where can hyaline cartilage be found?

Answer 4

precursor model for bones in the fetal skeleton

at articulating surfaces of bones such as the ribcage, larynx, nose, trachea, and bronchi
and at the epiphyseal growth plates

Question 5

what are the components fo elastic cartilage and what properties does it have?

Answer 5

proteoglycans
hyaluronic acid
type2 collagen

+ elastic fibres

give elasticity to cartilage in addition to the resilience characteristic of hyalin cartilage

Question 6

what can hyalin cartilage do which elastic cartilage cannot?

Answer 6

calcify with age

Question 7

where can elastic cartilage be found?

Answer 7

external ear (pinna)
Eustachian canal
epiglottis

Question 8

describe fibrocartilage

Answer 8

combination fo dense regular connective tissue and hyalin cartilage

cells are distributed in rows and there is no surrounding perichondrium

Question 9

components of extracellular matrix of fibrocartilage

Answer 9

proteoglycans
hyaluronic acid
type 2 collagen

and lots of type 1 collagne - thick between rows of chondrocytes

Question 10

where can fibrocartilage be found and what is its role?

Answer 10

intervertebral discs
menisci of joints
pubic symphysis

shock absorber and resists shearing forces

Question 11

give four functions of bone

Answer 11

mineral storage (e.g. calcium hydroxylapatite crystals)
support
protection
Haemopoiesis

Question 12

define bone

Answer 12

a vascular connective tissue consisting of cells and calcified extracellular matrix.

there are two types spongy and compact.

Question 13

describe the extracellular composition of bone

Answer 13

extracelluar matrix is caclified to act as a store of minerals e.g. calcium hydroxyapatite crystals. and consists of organic matter e.g. T1collagen, sulphated glycoproteins, proteoglycans and bound water.

Question 14

describe the composition of bone in terms of cells

Answer 14

osteoblasts - synthesise and calcify bone matrix, control formation, recruitment and maintenance of osteoclasts, initiation fo bone reabsorption

osteocytes - responsible for short term calcium and phosphate homeostasis of body

osteoclasts - bone resorption

Question 15

define cartilage

Answer 15

an avasular tissue consisting of extensive extracellular matrix in which lie chondrocytes

it is a supporting framework for organs, articulating surfaces of bone and fetal skeleton

Question 16

describe the microstructure of compact bone

Answer 16

denser than cancellous 
lamellar organisation is more precise and thicker 
covered by connective tissue 
marrow lined endosteum 
periostium

Question 17

describe the microstructure of cancellous

Answer 17

surrounded by compact bond
large open spaces for marrow
a network of fine bony columns and plates = trabeculae with several layers of lamellae.

Question 18

what is the cause of achondroplasia and give the morphological features?

Answer 18

point mutation in fibroblast growth factor receptor 3 gene.
autosomal dominant.

narrow epiphyseal growth plate - limbs v short
vault of skull enlarged but face is small. bridge of nose flattened
normal intelligence

Question 19

what are the common risk factors for osteoporosis?

Answer 19

use of steriods
genetic predisposition 
age 
white or asian descent 
women 
diet - insufficient absorption and vit D 
smoking, alcohol and sedentary lifestyle

Question 20

what are the gain in function results of the point mutation of achondroplasia?

Answer 20

poitn mutation in the fibroblast growth factor receptor gene =

decreased endochondral ossification
inhibited growth of chondrocytes in growth plates
decreased cellular hypertrophy
decreased cartilage matrix production

Question 21

define osteoporosis

Answer 21

a metabolic bone disease in which mineralized bone is decreased in mass to the point that it no longer provideds adequate support

there is enhanced bone resorption relative to bone formation

loss of mass in trabecular bone is particularly relevent to increase risk of fracture.

Question 22

describe the affect of 1,25 dihydroxylvitamin D3

Answer 22

increases calcium absorption in the small bowl

promotes mineralisation of bone

Question 23

describe the symptoms of Rickets

Answer 23

insufficient calcium deposition for adequate bone rigidity
long bonds become soft and malformed
distortion fo skull bone
enlargement of costochondral junctions of the ribs

Question 24

describe the symptoms of osteomalacia

Answer 24

bone pain
back ache
muscle weakness