Lecture 1

What are the four main types of bones in the human body?

Long bones, short bones, flat bones, irregular bones.

What structure surrounds the marrow cavity in long bones?

Diaphysis.

What is the periosteum?

A connective tissue covering the outer surface of all bones except at articular surfaces.

What type of bone structure is primarily found at the ends of long bones?

Epiphysis, which is mostly trabecular bone.

What region sits between the diaphysis and epiphysis?

The metaphysis

What is the endosteum?

The single layer celled inner aspect of bones where bone tissue faces bone marrow

What is the primary function of osteoblasts?

To secrete osteoid and initiate the mineralization of bone matrix.

What is the role of osteocytes in bone tissue?

To maintain bone matrix and sense mechanical strain.

What is the term for the fine processes extending from osetocytes that allow them to communicate with each other

Canaliculi

What are quiescent osteoblasts

Flattened cells covering resting bone surfaces which can differentiate into osteoblasts to initiate bone formation

What is the role of osteoclasts?

They are responsible for bone resorption by degrading bone matrix

What are the 2 phases of bone matrix and their chief cell type

Proteinaceous/organic phase → primarily type I collage

Mineral phase → hydroxyapatite crystals

What defines woven bone?

A haphazard arrangement that occurs during rapid expansion, such as in fetal development.

What is cortical bone

Bone that contains lamallae found as structures called osteon

Why are osteons found in cortical bone

They sit in line with the external forces → better resists the forces acting on the bone

What do Volkmann’s canals connect in bone structure?

They connect adjacent osteons and allow blood vessels to run between the periosteum and Haversian canals.

What process describes the formation of bone from cartilage in long bones?

Endochondral ossification.

What are interstitial lamellae?

Lamellae layers found between the osteons.

What distinguishes lamellar bone from woven bone?

Lamellar bone has a well-organized tissue arrangement, usually in sheets, and seen in mature bones.

What are Howship lacunae?

The resorption pits created by osteoclasts.

Name a type of bone that is primarily formed through intramembranous ossification.

Most flat skull bones.

Put these sentences into order of their occurrence. Which process is this describing ?

1. Condensation of embryonic mesenchyme into cell clusters

2. Formation of trabeculae network

3. Differentiation into osetoblasts

4. Formation of spicules of woven bone

5. Secretion of osteoid

Condensation of embryonic mesenchyme into cell clusters → differentiation into osteoblasts → secretion of osteoid → form spicules of woven bone → gradually forming a network of trabeculae

This process = intramembranous ossification

What is the precusor cell type for osteoblasts

Mesenchymal stem cells

What cells do haemopoietic stem cells differentiate into ?

Osteoclasts

What shape do circumferential lamellae have?

Circular in shape around a central canal.

What kind of blood supply does a typical long bone receive?

Blood from nutrient arteries, penetrating and non penetrating periosteal vessels, and medullary vessels.

What is the name of the circular region that consists of a central blood vessel and nerve branches within an osteon

Haversian canal

What is trabecular bone

It comprises a network (lattice or mesh) of bone plates and rods interspersed with spaces containing bone marrow and blood vessels