Histology (bone and cartilage)

Bismillahirahmanirrahim

OK.. now I'll share about 'Cartilage' in our body =)

Cartilage arise from mesenchymal. It consist of :

1. Cell (Chondrocyte & Chondroblast)

2.Connective tissue

3. Ground substance (Non vascular. Got nutrient from diffusion)

There are 3 types of cartilage :

1. Hyaline cartilage

2. Elastic cartilage

3. Fibro cartilage

Hyaline and elastic cartilage were covered by 'perichondrium'. 
Perichondrium consist of 2 layers.
1. Outer : vascular connective tissue + type I collagen

2. Inner : chondrogenic that give rise to chondroblast (that secrete cartilage matrix)

Cartilage matrix produce and maintain chondrocyte & chondroblast. Contain large aggregate of proteoglycan and highly hydrated.

Mature cell for cartilage : Chondrocyte (enclose in lacunae)

"Hyaline cartilage"

* Most common : serve skeletal muscle

* Can be replace by bone during endochondral ossification

*Contain type II collagen

*Can be found : 

(TEN BeBaL)

T- Trachea

E-End of Ribs

N- Nose

B-Bronchi

B-Bone

L-Larynx

"Elastic cartilage"

*For structural support & increase flexibility

*Contain : elastic fibre in matrix & highly flexible

* Found in :
(EEA)

E-External ear

E-Epiglottis

A-Auditory tube

" Fibro cartilage"

*Dense bundle of type I collagen

*Function:

(TBR)

 T-Tensile strength

B- Bear weight

R- Resist compression

*Found in :

-Invertebral disc

-Certain joint

-symphysis pubis

"Bone"

Picture above shows 'compact bone'

Info based on picture :

- In compact bone, collagen fibre arranged in lamellae

- Deep to periosteum is circumferential lamellae

-Lamellae surrounding bone marrow

-Osteon also exist and known got 'Haversian system'.

-Between Harversian system : central canal

Bone matrix :

-Highly vascularized (calcified diffusion)

-Major component : Collagen fibre

-Glycoprotein component bind to calcium (mineraliztaion)

Bone usually continually remodal those thing :

1. mineral needs

2. Mechanical stress

3. Thinning/disease

There are 2 hormone involve in this :

1.Thyroid :- Inhibit action of osteocyte. Thus, decrease the bone re-absorption.

2.Parathyroid hormone :- Stimulate osteocyte. Increase bone reabsorption and  release calcium into blood.

Okay.. Now, lets talk about 'cell in bone'

Basically, we need to know 3 things :

1. Osteoprogenitor cell that located in :

(PEOP) 

P-Periosteum

E-Endosteum

O-Osteon

P-Perforating canal

2. Osteoblast :

-It's on bone surface

-Synthesized bone matrix

3. Osteocyte :

-mature cell of osteoblast

- Branch located in lacunae

-Use canaliculi for communication and exchange

-maintain bone & blood homeostasis in terms of calcium and phosphate

Ok.. I hope you enjoying this :)