Bone

Characteristics	Cartilage	Bone
Blood vessels	not supplied	supplied
Nerves	no	present
Repair		can repair
Use	withstand Compression and flexibility at pointy regions	produce blood cells, storage of minerals,strength
Collagen	predominatly *** type 2 *** with elastin and few type 1	only type 1
Cell housing	lacunae with daughter cells	lacunae with no daughter cells
Communication	No communication	Communicates via cannaluci with other Osteo-cyst
Macrophage	no	Osteoclast

Types of Bone formation

Characteristics	Intramembranous Ostification	Endo-chondrial Osteofication
BluePrint	No	Yes, On chondriocytes plan
Bones	Flat Bones	Long bones
Examples	Skull,mandible,maxilla,Clavicle,Pelvis	Femur,Tibia

Formation of bones

1. Intramembranouus Bone Formation

graph TD
    X{Mesenchymal stem cell} ==>|proliferate to site of bone formation| A[turns to OSteo-progenitor cells];
    A ==>|divides to| B[Osteo-blast];
    B ==>|produces ECM then to | C[Osteo-cytes];
    V{Monocytes} ==>|goes to Bone| Y[Osteo-clasts];

1. Endo-Chondrial Ostification

graph TD
    X{initial Cartilage Blueprint } ==>|Surrounded by| A[Peri-Chondrium except the Articular Region];
    A ==>|@ the middle collar site then spreads to both ends| A1[Peri-Chondrium is replaced by Peri-osteum];
    A1 ==> A1a[<ul> Primary Centre for Ostification</ul>];
    A1a ==>|reduction of nutrients to Chondrogenic-cytes| A2[Cell swelling];
    A2 ==> A3[Hypertrophy];
    A3 ==> A4[Calcification of Osteo-cytes cell];
    A4 ==>|recruits Blood vessels| A5[ brings <ul>Osteo-clast and OSteo_progenitor cells</ul>];
    A5 ==>|osteo-clasts eats calcified dead cartilage ,oste-blast of osteo-progenitor forms| A6[<ul>Waven Bone</ul>];
    A6 ==>|this happens at Diaphysis, <ul> at Ephypsis</ul>| A7[Peri-chondrium is replaced to Peri-ostium by above Process and forms Waven bone except the Articular region as it lacks Perichondrium to form Peri-Osteum];
    A7 ==> A8[<ul> Secondary centre of Ostification </ul>];
    A8 ==> A9[ <ul> Both Primary and Secondary Ostification never joins </ul>];
    A9 ==>|leaving a region between them | A10[<ul> Epiphyseal Growth Plate</ul>];
    A10 ==> A11[<mark> Epiphyseal Growth plate grows ,which cause child increase in height </mark>];

Layers of Epiphyseal growth plate

From Secondary Ostification center

• Zone of Reserve
• Zone of Profileration
• Zone of Hypertrophy
• Zone of Calcification
• Zone Of Ostification

Primary Ostification Centre

Development of Waven bone to mature bone

graph TD 
    A{Waven bone = irregular collagen fibres laid } ==> B{lamellar bone  organised layout of Collagen };
    B ==> A1[Spongy bone];
    B ==>A2[compact bone];

Compact bone formation from Waven bone

graph TD
    X{Newly Waven bone} ==> A[destroyed by osteo-c last *** by Tunneling ***];
    A ==> A1[new blood vessels and nerves enters into the tunnel];
    A1 ==> A2[osteo-blast comes via blood];
    A2 ==> A3[osteo-blast secrete osteoium in *** circular fashion from outside to inside *** ];
    A3 ==> A4[osteoblast matures to *** Osteo_clast at each circles];
    A4 ==> A5[At the end leaving out only tiny hole at the middle *** Haversian Canal ***];
    A5 ==>Xx{containes *** Blood vessels.Nerves *** };
    Xx ==>|each HAversian Canals Blood vessels and Nerve joined by | Xav{ *** Volkmann's Canal *** };

Paget's Disease

Have *** Increased osteoclast Acativity *** HAve *** Reduced and Irregular Osteo-blast Activity *** ==> No Circular Depositon of COllagen 1 —->No osteon(no single Haversian system) which leads to weak bone and Compression of Nerves in Haversian Canal.

1. Strength Of Bones

   graph TD
       A[Osteo-blasts] ==>|secretes| B{ECM};
       B ==> B1[Collagen 1 + Ground Substance ]
       B1 ==>|Collagen Binding| D[10% inorganic Substances];
       D ==>|strength = deposition of | D1(calcium and Phosphate to for *** hydroxyapatite *** )

osteogenesis Imperfecta

*** Error in Type 1 collagen gene *** Leads to brittle bones

OSteo-malacia

*** Calcium deficiency which leads to loss of calcium in bone ***

Osteo-Clast

graph TD
    A[osteoblast] ==>|produces| B[ECM = Collagen 1]
    B ==>|calcium and phosphate deposits| C[forms bone *** Spicules ***];
    C ==>|bone spicules joins to form| D[*** Trabeculae ***];
    D ==>|the spaces between the Trabeculae| E[Bone marrow];
    A ==>|osteoblast mature to| A1[osteo-cyst in lacunae];
    A1 ==>|all osteo-cyst *** joins Together *** and forms| A2[Canaliculus *** by cytoplasmic projection *** ];

Mechanism of Osteoclast

• Binds to Bone matrix
• Releases *** Hydrolytic Enzymes *** and releases calcium and Phosphate
• Forms *** Howship's Lacuna *** the site of listing action

Calcium Managment

• 1111

  graph TD
      A{abnormal Calcium} ==>|:octicons-arrow-down-24: blood calcium| 1[Secretion of PTH ];
      1 ==>|in Kidney| 1a1[Conversion of 25-Calciferol to 1,25-hydroxyCalciferol];
      1 ==>|in kidney| 1a2[Increase Calcium re-absorption, reduce Phosphate Reabsorption];
      1 ==>|in Bone| 1a3[Acutely Increase in Osteoblast activity];
      1a3 ==>|cytokines from Osteo-blast| Ax4[Activates Osteo-clast to releases Calcium and Phosphate ];
      1a1 ==> 1a1a[VItamin D to mineralise bone as PTH demineralise bones ];
      1a1a ==>|in GI| 1a1a1[Increase Calcium and phosphate Absorption and Increase Calcium binding Protein CAlbindin @8K];
      1a1a ==>|kidney| Ax1a2[CAlcium and Phosphate reabsortion];
      1a1a ==>|bone| Ax1a3[Increase OSteo-clast activity for new bone formation ];
      A ==>|elavated Calcium| A1[Calcitonin];
      A1 ==> A1a[inhibit osteo_clast ];
  

Osteo-Porosis

Increased Osteoclast activity > osteoblast ==> Weak bones

Bone Covers

graph TD
    X{covers of bone } ==>|outside bone| A[Periosteum];
    X ==>|inside =around spongy bone | B[Endosteum];
    A ==>|on bone| A1[Osteo-genic periosteum,contains Osteo-genic stem cells];
    A ==>|over Osteo-genie Periosteum| A2[Fibrous Peri-osteum,containsblood vessels];
    B ==>|one layer of | B1[osteo-Progenitor Cells];

Bone Repair

graph TD
    X{fracture} ==> A[hematoma formation];
    A ==> A1[recruitment of Chondrio-Progenitor cells];
    A1 ==> A2[hyaline Cartilage];
    A2 ==> A3[Endo-Chondrial Ostification];

Cartilage Repair

graph TD
    X{fracture of Cartilage} ==> A[Damage of Chondrio-cyte];
    A ==>|as Stem cells present only at Ends and no Connection between Chondrio-Cytes, loss of nutrient supply to the centre damaged region| A1[Hypertrophy of Chondrio-cites damaged ];
    A1 ==> A2[Calfication of Chondrio-Cytes damaged];
    A2 ==> A3[Endo-Ostification of Cartilage ];
    A3 ==> A4[loss of Flexibility of cartilage];

Gigantism vs Acromegaly

Abnormal Secretion of Growth Hormone from Pituitary or from a Adenoma

graph TD
    X{ abnormal GH in Children} ==> A[Increase in growth of cartilage and bones];
    A ==> A1[As Epiphyseal plate is not fused];
    A1 ==>A2[Epiphyseal growth plate];
    A2 ==> A3[<mark> Gigantism </mark>];
    Y{abnormal GH in Adults} ==> B[Increase in growth of cartilage and bones];
    B ==> B1[As Epiphyseal plate is fused];
    B1 ==> B2[Increase in width of bones];
    B2 ==> B3[<mark> Acromeagaly </mark>];

Acondrio-plasia

Genetic Disorder in mitosis of Chondrial cells

graph LR
    X(No mitosis of Chondrial cells) ==> A1[no cartilage growth]
    A1 ==>A2[no zone of Proliferation function @ Epiphseal Growth plate];
    A2 ==> A3[No height increase ];
    A3 ==>|Growth Hormone| A4[increase in width of bones];