Bone, Bone Marrow, Blood And Blood Vessels

Question 1

Name the bones of the axial and appendicular skeleton

Answer 1

Axial skeleton = 80 bones which includes the skull, thoracic cage, and vertebral column.
The Appendicular skeleton contains 126 bones and includes the Shoulder Girdle and upper limbs, as well as the pelvic girdle and lower limbs

Question 2

Explain how the bone is a living tissue

Answer 2

The bone is a living tissue as it is made up of cells (osteoblast, osteocytes, osteoclasts, etc.) and collage outs fibres but unlike other parts it has a hard calcified matrix

Question 3

How is bone formed and how does it undergo remodelling

Answer 3

Bone formation in utero - Flat bones develop directly from mesenchymal tissue, by intro-membranous ossification. Long bones require a cartilage template in order to develop by endochondral ossification
Bones undergo remodelling in two steps:
The osteoclasts make a wide tunnel in the bone (cutting cone)
The osteoblast make a smaller tube of cortical bone (closing cone)

Question 4

Describe the composition of bone in terms of its cells and extra cellular components

Answer 4

There are two types of bone tissue, of different porosity found in the body:
- Compact (dense) bone is hard and forms the generally smooth outer layer of bones
- Spongy (cancellous) bone is found deeper and is porous and highly vascular.
Bone is surrounded on the outside by a tough vascular fibrous connective tissue layer (periosteum), whilst a thin cellular layer (endosperm) that lines the marrow cavity can be found internally

Question 5

Describe the microstructure of compact (cortical) and spongy (cancellous/trabecular) bone.

Answer 5

Cancellous bone forms a network of fine bony columns or plates called trabecular to combine strength with lightness. The spaces are filled with bone marrow.
Compact bone forms the external surfaces of ‘named bones’ and comprises of 80% of the body’s skeletal mass

Question 6

Recognise compact bone (including its cells, lacunae, canaliculi, Haversian and Volkmann’s Canals, lamallae and periosteum), and trabecular bone from photomicrographs

Answer 6

Page 13 body logistics workbook 2

Question 7

Explain the importance of vitamin D in normal bone stability

Answer 7

Vitamin D is important as it is absorbed to produce calciferol, which is used for calcium absorption, to keep the bones strong and stable

Question 8

Where is the bone marrow and what is the function

Answer 8

The central cavity (medullary region), contains bone marrow. There are two types:
- Red marrow where active blood cell formation (haemopoisis) occurs
Yellow marrow which contains adipose (fat tissue) and where haemopoiesis does not occur but acts as an energy source.

Question 9

Describe how the morphology and/or mechanical properties of bone can change in disease

Answer 9

Disease can affect bone stability as it can alter the activity of osteocytes which can affect
- osteitis recycling
- bone depletion
- bone resorption
It can also affect nutrition such as
- Vitamin D deficiency
Vitamin C deficiency
- Vitamin K and Bb12 deficiency

Question 10

Describe the genetic basis and phenotypical changes in osteogenesis imperfecta

Answer 10

It is a mutation in the COL1A gene. It causes incorrect production of collagen 1 fibres. Causes weak bones and increased fracture risk. Causes shortened height and stature. It mostly affects neonates and children

Question 11

Describe the features of bones affected by rickets and osteomalacia, the difference e between the two conditions.

Answer 11

Vitamin D is essential for normal ossification. In its absence a poorly mineralised, pliable matrix (osteosarcoma) is formed, which does not become mineralised properly by hydroxyapatite contains calcium and phosphate.
Affected bones are unable to support individuals body weight and so bend. They make people abnormally prone to fractures. In childhood, growing bones are affected causing rickets. This is seen in a bow shaped leg appearance.
Osteomalacia is a similar process in adults whey bones become pliable during the process of remodelling.

Question 12

Explain the importance of dietary and behavioural factors in the prevention of rickets and osteomalacia

Answer 12

Including vitamin D in the diet and having calcium rich bones, as well as frequently going in the sunlight (provides vitamin D), especially in pregnancy as foetus puts a demand on calcium, can help prevent these diseases

Question 13

Describe the radiological and structural changes occurring is osteoporosis

Answer 13

Osteoporosis is the most common bone condition affected the elderly. There is a list of bone matrix, a loss of structure integrity and demineralisation. This increase the risk of bone fractures, especially in the spine, hip and wrist. Accelerate bone loss occurs in post menopausal women, with the main contributed factors being reduced oestrogen stimulation of the osteoblast and increased osteoclasts activity.

Question 14

How can osteoporosis be delayed/prevented

Answer 14

Bone loss can be abrogated through dietary factors, excessive and good health. The use of oestrogen replacement therapy can delay the decline of bone reabsoption in post menopausal women but it can have its own adverse effects.

Question 15

List the common risk factors and explain the importance of osteoporosis as a risk factor for fractures in the elderly

Answer 15

Age is the main risk factor with bone loss occurring in all individuals after the age of 39. Accelerated bone loss occurs in post menopausal women, with the main contributing factors being reduced oestrogen stimulation of the osteoblast and increased osteoclasts activity.
There are other factors such as genetic, nutrition, activity levels and smoking

Question 16

Outline the cause and morphological features of achondroplasia

Answer 16

One of the most commons forms of short limb dwarfism and is caused by an autosomal dominant point mutation in the fibroblast growth factor receptor 3 gene (FGFR3). Fibroblast growth factors activates Chondrocytes to lag down new cartilage so FGFR3 plays a key role in bone development and maintenance. Point mutation causes a loss of function of the FGFR3 gene causing decreased endochondral ossification, inhibited proliferation of Chondrocytes in growth plate cartilage, decreased cellular hypertrophy and decreased cartilage matrix production.
As a result, the limbs of affected individuals are very short with shortening most prominent in the proximal segment (upper arms and legs) where long bones grow.

Question 17

Describe the characteristic features and functions of long bone

Answer 17

Long bones are longer than they are wide. They include: the femur, and small bones in the finger. Long bines are mostly located in the appendicular Skelton.
The function is to support the weight of the body and facilitate movement.

Question 18

Describe the characteristic features and functions of short bones

Answer 18

Short bones are approximately as long as they are wide. They include: the wrist and ankle joints, the carpals in the wrist (scaphoid) and the tarsals in the ankles (calcaneus)
The function of short bones is to provide stability and some movement

Question 19

Describe the characteristic features and functions of flat bones

Answer 19

Flat bones are somewhat flattened with roughly parallel opposite edges. They include: the skull (occipital), thoracic cage (sternum and ribs), the pelvis (ilium).
The function of flat bones is to protect the internal organs and to also provide large areas of attachment for muscles

Question 20

Describe the characteristic features and functions of irregular bones

Answer 20

Irregular bones vary in shape and do not fit in any other category and often have a fairly complex shape. They include: the vertebra and sacrum.
The function of irregular bone is to protect internal organs. Vertebrae in the ventral column protect the spinal cord and the pelvis (sacrum) protect organs in the pelvic cavity. They provide an important ‘anchor’ points muscle groups

Question 21

Describe the characteristic features and functions of Sesamoid bones

Answer 21

Sesamoid bones are bone embedded in tendons. They are small, round bones found in the tendons of hands, feet and knees, the Patella is an example of a Sesamoid bone - generated post-natally
The function of Sesamoid bones is to protect tendons from stress and damage from repeated ‘wear and tear’

Question 22

Describe the constituents of bone marrow and how they differ from cells in blood in structure and function

Answer 22

Two types of bone marrow
Red marrow is full of developing blood cells. They have a rich blood supply and only found in spongey bone. Their function is to replenish cells in the blood (haemopoisis)
Yellow marrow is full of adipocyes and have a poor blood supply. Their function is a shock absorber and energy source. They can convert to red marrow.
Bone marrow are found in the spaces in Cancellous bone

Question 23

Describe the structure and function of blood vessels from the largest arteries and veins to the end arterioles and venules

Answer 23

Veins - transport blood to the heart. 3 layers - Tunica intima (endothelial cells), Tunica media (elastic fibres and smooth muscle cells), and Tunica externa (elastic fibrous capsule). Can be categorised as pulmonary veins, systemic veins, superifcial veins and deep veins.
Arteries convert blood away from heart. 3 layers - Tunica intima (elastic membrane lining), Tunica media (smooth muscle and elastic fibres), Tunica Externa (composed of collagen and elastic fibres). Walls are much thicker

Question 24

Explain the functional significance of the blood vessels including communicating vessels

Question 25

Name the major blood vessels of the body and determine whether they contain oxygenated or deoxygenated blood or a mixture of both.