Lecture 6 - Bones

Question 1

What is the axial skeleton’s job?
How many bones does it have?

What is the appendicular skeleton’s job?
How many bones does it have?

Answer 1

Organ protection; 80 bones

Movement; 126 bones

Question 2

How is bone classified and what are the categories? Give examples and characteristics of each (5)

Answer 2

By shape

Long - femur, two articulations surfaces and mostly compact bone

Short - wrist, cube shaped and thin layers of compact bone surrounded by spongy centre

Flat - skull, parallel layers of compact bone surrounded by spongy centre

Irregular - vertebrae, thin layers of compact bone surrounded by spongy centre

Sesamoid - patella, embedded in tendon/muscle

Question 3

Describe the structure of the long bone, including sections and what is within them

Answer 3

Proximal epiphysis - articular cartilage, spongey bone, red bone marrow and epiphysial line (allows growth)

Metaphysis - compact bone just below bone knob

Diaphysis - long bit, compact bone;
On the inside is the endosteum (connective tissue, bone forming cells), medullary cavity (yellow bone marrow, triglyceride stores) and artery
On outside is periosteum (connective tissue, bone forming cells; for protection, repair, nourishment, attachment of ligaments and tendons)

Metaphysis again

Distal epiphysis - bottom, articular cartilage

Question 4

What are the two types of bone marrow and the characteristics?

Answer 4

Red - production of RBC’s, platelets and white cells

Yellow - higher fat content, and some white cells

Question 5

There is a conversion of * to * bone marrow as you age

Answer 5

Red to yellow

Question 6

Yellow bone marrow tends to be in ** of bone and red at **

Answer 6

The middle

The ends

Question 7

What can exercise do?

What are marrow adipocytes high in?

What may marrow adipocytes restrict?

Answer 7

Alter ratio of red to yellow bone marrow

Yellow marrow

Haemopoiesis (production of blood cells in bone marrow) and osteoblast activity

Question 8

What does marrow adipose tissue act as to produce?

What are the consequences?

Answer 8

Endocrine organ to increase serum adiponectin

This substance has bad effects on metabolic and cardiovascular outcomes

Question 9

What is the bone structure like inside the metaphysis? (5/6)

Answer 9

Has blood vessels including a central Haversian canal 
Has compact bone on top and spongey bone downwards (light, stress resistant, transfer force and supports/protects bone marrow)
Has trabeculae (partitions formed by bands of connective tissues)
Has osteons (part of Haversian system, repeating units along a line of stress)
Has lamellae (layers)

Question 10

What is the osseous tissue of skeleton made of?

Answer 10

Compact bone - 75-80%

Spongey bone - 20-25%

Question 11

What is the extracellular matrix of bone made from?

What is the majority substance made from?

Answer 11

25% H2O
25% collagen fibres for flexibility
59% crystallised mineral salts (for hardness) - made from calcium phosphate/carbonate and mineral deposition via collagen fibres a.k.a calcification

Question 12

What are the four cell types of bone?

Answer 12

Osteogeneic cell
Osteoblasts
Osteocytes
Osteoclasts

Question 13

Where are osteogeneic cells found and what do they undergo?

Answer 13

Found in inner periosteum, endosteum and bone canals with blood vessels

Undergo cell division to form osteoblasts

Question 14

What do osteoblasts do?

Answer 14

Build bones, make and secrete collagen for the extracellular matrix, initiate calcification and become osteocytes when trapped in extracellular matrix

Question 15

What are osteocytes and what do they do?

Answer 15

They’re numerous mature cells that maintain metabolism and exchange nutrients and waste with blood

Question 16

What are osteoclasts and what do they do?

Answer 16

They’re large cells formed by monocyte fusion, and they breakdown the extracellular matrix by release of enzymes/acids (opposite to osteoblasts)
Control aspects of bone function

Question 17

Where are osteocytes in bone?

Answer 17

In osteons

Question 18

What is the appendicular skeleton made of?

Answer 18

Bones of the upper and lower limbs, and girdles that attach limbs to axial skeleton