The Musculo- skeletal System Flashcards
What are the 5 basic tissues of the musculoskeletal system
Bones
Ligaments
Cartilage
Skeletal muscles
Tendons
How many bones are in the skeleton
Made up of 270 bones at birth and merge to become 206.bones adult
What are the 5 bone types
Flat bones- sternum
Irregular bones- vertebrae
Sesamoid bones- patella
Long bones- femur
Short bones- metacarpals/tarsals
Describe bones
Are highly vascular living structures that are continuously being remodelled
Form a rigid framework to which soft tissues and organs are attached
What are the functions of the skeletal system
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
What is spongy bone tissue
Porous
Highly vascularised
“Honeycomb “
Function- reduces bone density, allows end of long bones to compress as a result of repeated stress
What is compact bone tissue
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
What are the long bones
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
What are long bones ( continued)
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
What are the other bone structures
Thin outer layer of compact bone
Spongy bone inside containing red bone marrow
Surrounded by periosteum
What are the three types of bone cells
Osteoblasts, osteocytes and osteoclasts
What are osteoblasts
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
What are osteocytes
Mature bone cells= they do not divide and are responsible for bone formation and calcium homeostasis
What are osteoclasts
Bone-reabsorbing cells= breakdown bone releasing calcium and phosphate, as new bone cells are made, old ones are destroyed by osteoclasts
What are the stages of osteogenesis
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)
Describe ossification
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
Ossification ( continued)
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
What is bone growth
Bone moves outwards from centre
As osteoclasts become osteoblasts see the development of epiphyses plate
The osteoblasts form a matrix and become spongy bone
What is the hormonal regulation of bone growth
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
What is the link between exercise and bone health
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
What are the different vitamins for healthy bones
Vitamin A - needed for osteoblast activity
Vitamin C - used in collagen synthesis
Vitamin D- required for calcium and phosphate absorption from the gastrointestinal tract
What is bone remodelling
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
What are the 4 stages of bone healing
1st stage = haematoma formation
2nd stage = callus formation
3rd stage = bony callus formation
4th stage = re canalisation and remodelling
Describe 2nd stage of bone healing
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
Describe 3rd stage of bone healing
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
Describe 4th stage of bone healing
Process of remodelling converts the external callus to compact bone
Whole process can take months
