Osseous Tissue

Question 1

Osseous tissue

Answer 1

A type of connective tissue, contains cells that are surrounded and embedded within an extracellular matrix

Question 2

Extracellular matrix

Answer 2

25% water
25% collagen fibres (give bones some flexibility)
50% crystallised mineral salts (give the bone its hardness)

Question 3

Cell types in osseous tissue

Answer 3

Osteoprogenitor cells
Osteoblasts
Osteocytes
Osteoclasts

Question 4

Osteoprogenitor cells

Answer 4

Unspecialised stem cells
Only bone cell that can divide
Progenitors of osteoblasts and osteocytes

Question 5

Osteoblasts

Answer 5

Synthesise and secrete collagen fibres and other components of the extracellular matrix
They initiate calcification, the crystallisation of mineral salts
Initiate Ossification by
secreting osteoid

Question 6

Osteoid

Answer 6

Unmineralised, organic portion of the bone matrix that is subsequently mineralised

Question 7

Osteocytes

Answer 7

Mature bone cells and most numerous cells
Responsible for the day to day metabolism of osseous tissue (exchange of nutrients and wastes)
Exchange aided by cytoplasmic projections in canaliculi (little canals)
Formed when osteoblasts become surrounded with bone matrix

Question 8

Osteoclasts

Answer 8

Large multinucleate cells
Release enzymes and acids that digest the extracellular matrix
Involved in resorption of osseous tissue
(important for development, maintenance and repair)

Question 9

Compact bone location

Answer 9

Found in diaphysis of long bones, surface or short, flat and irregular bones

Question 10

Compact bone functions

Answer 10

Provides protection and support and resists stress of weight movement

Question 11

Compact bone chracterisitics

Answer 11

Very few spaces

High tensile strength due to the types of materials used and how they are arranged

Question 12

Osteon

Answer 12

Repeating structural unit of compact bone

Consists of central canal containing blood vessels surrounded by concentric lamellae, osteocytes, lacunae and canaliculi

Question 13

Concentric lamellae

Answer 13

Rings of hard, calcified extracellular matrix

Question 14

Osteon location

Answer 14

Arranged along the lies of stress experienced by the bone

In long bones, arranged parallel to changes in stress

Question 15

Lacuna

Answer 15

Small space located between lamellae

Spaces contain osteocytes (maintenance cells of osseous tissue)

Question 16

Canaliculi

Answer 16

Small channels filled with cellular projections and extracellular fluid that radiate from the lacuna
Provide routes for oxygen and nutrients to reach the osteocytes

Question 17

Central canals

Answer 17

Run through the centre of osteons
Connect with perforating canals
Surrounded by concentric lamellae

Question 18

Perforating canals

Answer 18

Allow blood vessels, lymphatic vessels and nerves to enter compact bone

Question 19

Interstitial lamellae

Answer 19

Areas between osteons
Also contain lacuna, canaliculi and osteocytes
Fragments of old osteons that have been broken down during bone remodelling

Question 20

Circumferential lamellae

Answer 20

Lamellae that surround the rest of the bone

Question 21

Spongy bone location

Answer 21

Found in the epipysis of long bone, most short flat and irregular bones

Question 22

Characteristics of spongy bone

Answer 22

Contains lamellae that are arranged in columns (trabeculae)
Spaces between trabeculae make tissue light
Spaces can also contain red bone marrow

Question 23

Trabeculae (small beam)

Answer 23

Contain osteocytes within lacuna
Canaliculi connect lacuna
Orientated along the lines of stress