The Musculo- skeletal System

Question 1

What are the 5 basic tissues of the musculoskeletal system

Answer 1

Bones
Ligaments
Cartilage
Skeletal muscles
Tendons

Question 2

How many bones are in the skeleton

Answer 2

Made up of 270 bones at birth and merge to become 206.bones adult

Question 3

What are the 5 bone types

Answer 3

Flat bones- sternum
Irregular bones- vertebrae
Sesamoid bones- patella
Long bones- femur
Short bones- metacarpals/tarsals

Question 4

Describe bones

Answer 4

Are highly vascular living structures that are continuously being remodelled
Form a rigid framework to which soft tissues and organs are attached

Question 5

What are the functions of the skeletal system

Answer 5

Providing body framework
Giving attachment to muscles and tendons
Allowing movement of the body as a whole and in parts because of joints
Forming the boundaries of the cranium, thorax and pelvis, and protecting organs
Haemopoiesis (production of blood cells in red bone marrow)
Mineral storage

Question 6

What is spongy bone tissue

Answer 6

Porous
Highly vascularised
“Honeycomb “
Function- reduces bone density, allows end of long bones to compress as a result of repeated stress

Question 7

What is compact bone tissue

Answer 7

Makes up the hard outer layer, compact due to its minimal gaps and spaces
Tissues gives bones their smooth, white and solid appearance, accounts for 80% of total bone mass
Contains nerves and blood vessels

Question 8

What are the long bones

Answer 8

Are elongated, slender bones found mainly in the limbs
Diaphysis (shaft) is composed of compact bone - central medullary canal containing fatty yellow bone marrow
Epiphyses( extremities) - outer covering of compact bone with spongy bone inside

Question 9

What are long bones ( continued)

Answer 9

Hyaline cartilage to prevent damaging bone-bone contact
Vascular membrane
Outer layer is tough to protect bone underneath
Inner layer contains bone cells for bone production and breakdown, repair and remodelling
Main arterial nutrient supply to diaphysis
Epiphysis has own blood supply
Bone is full of nerves- break’s painful

Question 10

What are the other bone structures

Answer 10

Thin outer layer of compact bone
Spongy bone inside containing red bone marrow
Surrounded by periosteum

Question 11

What are the three types of bone cells

Answer 11

Osteoblasts, osteocytes and osteoclasts

Question 12

What are osteoblasts

Answer 12

Bone-building cells= they deposit new bone tissue around themselves, they eventually become trapped in tiny pockets in the growing bone and differentiate into osteocytes

Question 13

What are osteocytes

Answer 13

Mature bone cells= they do not divide and are responsible for bone formation and calcium homeostasis

Question 14

What are osteoclasts

Answer 14

Bone-reabsorbing cells= breakdown bone releasing calcium and phosphate, as new bone cells are made, old ones are destroyed by osteoclasts

Question 15

What are the stages of osteogenesis

Answer 15

Stage 1= osteoblasts secrete osteoid ( replaces cartilage in foetus)
Stage 2= calcium and phosphate laid down ( progressively calcifying it, converting it to hard rigid mature bone)
Stage 3= osteoblasts form a matrix (cells become trapped and become osteocytes)

Question 16

Describe ossification

Answer 16

Bone starts of as a cartilage like rod
Ossification starts in centre and moves from centre outwards
As ossification continues diaphysis lengthen
Blood supply & blood vessels as well as nervous tissue help growth & formation of compact bone
Secondary centres of ossification begin the growth of compact bone in the epiphyses
Spongy bone growth is stimulated by the transformation of osteocytes into a matrix becoming osteoblasts

Question 17

Ossification ( continued)

Answer 17

As we age ( from foetal development to adulthood) the osteoblasts concentrate at the ends of the bone (epiphyses) and compact bone forms a strong, tough outer
Centre of bone is called medullary canal: contains bone marrow

Question 18

What is bone growth

Answer 18

Bone moves outwards from centre
As osteoclasts become osteoblasts see the development of epiphyses plate
The osteoblasts form a matrix and become spongy bone

Question 19

What is the hormonal regulation of bone growth

Answer 19

HGH ( human growth hormone) and thyroxine and tri- iodothyronine promote bone growth in the foetus
During puberty testosterone and oestrogen increase both bone density and mass
Calcitonin and parathyroid hormone control uptake and ensure that bone density is maintained
Calcitonin increases uptake of calcium
Parathyroid decreases uptake of calcium
During menopause women are more at risk of osteoporosis due to oestrogen levels dropping

Question 20

What is the link between exercise and bone health

Answer 20

Once epiphyseal plates have ossified bone growth ceases
However bone can thicken and strengthen throughout life
Osteons laid around the bone periphery by osteoblasts present in the periosteum
Weight bearing exercises can thickening& strengthening and lack can do the opposite
Healthy bones need vitamins A,C,D also calcium& phosphate, iron and manganese

Question 21

What are the different vitamins for healthy bones

Answer 21

Vitamin A - needed for osteoblast activity
Vitamin C - used in collagen synthesis
Vitamin D- required for calcium and phosphate absorption from the gastrointestinal tract

Question 22

What is bone remodelling

Answer 22

Bone constantly being remodelled and regrown due to continued damage through water and tear and trauma
Constant turnover of bone tissue
Where areas are under constant friction are replaced every 3-6 months but overall approx 10% of bone material is replaced every year

Question 23

What are the 4 stages of bone healing

Answer 23

1st stage = haematoma formation
2nd stage = callus formation
3rd stage = bony callus formation
4th stage = re canalisation and remodelling

Question 24

Describe 2nd stage of bone healing

Answer 24

Haematoma stabilised with large amounts of fibrin
This lays framework for granulation
Fibroblasts migrate to site and lay down collagen tissues
Osteoblasts lay down new osteoid and these bone ends join the tissue
Macrophages phagocytoses dead bone and other tissue
New capillaries grow to supply blood and nutrients

Question 25

Describe 3rd stage of bone healing

Answer 25

Approx 2 weeks later bony callus forms as osteoblasts calcify the osteoid
Callus is laid done as spongy bone and brings together ends if broken bones
This supports and splints the fracture

Question 26

Describe 4th stage of bone healing

Answer 26

Process of remodelling converts the external callus to compact bone
Whole process can take months