The Skeletal System Flashcards
What are the functions of bone & skeletal system
1) Support- structural framework
2) Protection
3) Assisting in movement
4) Mineral homeostasis
5) Production of blood cells- red bone marrow
6) Triglyceride storage - yellow bone marrow
What is Haemopoiesis
Production of blood cells
What does red bone marrow produce?
red blood cells , white blood cells, and platelets
What cells does yellow bone marrow produce?
Adipose cells
Why are triglycerides stored?
As a potential chemical energy reserve
What are the types of bones
Long, short, flat, irregular bones.
Compact and cancellous bone
What is an extracellular matrix composed of?
25% water, 25% collagen fibres, 50% crystallised mineral salts
Describe compact bones
1) Contains few spaces, made up from Osteons
2) Found beneath the periosteum and makes up the bulk of the diaphysis in long bones
3) Provides protection and support and resists the stresses of weight and movement
Describe spongy bones
1)an irregular lattice work of bone
2) Lighter than compact bone so it moves more readily when pulled by skeletal muscle
3) Supports and protects red bone marrow
What is ossification and what are the 4 principal situations in which it occurs
Bone formations. Occurs in 4 principal situations:
1) initial formation of bones in an embryo and foetus
2) growth of bones during infancy and childhood
3) remodelling of bone during lifetime
4) repair of fractures
Describe growth in bone length related to the epiphyseal plate
As bone grows, new cells on the epiphyseal side are formed, while old cells on the diaphyseal side are replaced by bone, so bone grows on the diaphyseal side
Describe growth in bone thickness
You have continual bone formation inside of bone, as well as bone destruction caused by osteoclasts inside the medullary cavity. Bone destruction occurs at a slower rate so the medullary cavity enlarges as the bone increases in thickness
What is bone resorption
Removal of minerals and collagen fibres from bone by osteoclasts (results in destruction of extracellular matrix)
What us bone deposition
The addition of minerals and collagen fibres to bone by osteoblasts (results in formation of extracellular matrix)
What is bone remodelling
The ongoing replacement of old bone with new
Describe bone fractures
- Can be partial, complete, closed (simple) or open (compound)
- Repair involves several steps
-Phagocytes remove dead bone tissue - Chondroblasts form fibrocartilage that bridges the broken ends of the bone
- Fibrocartilage turns into spongy bone
- Remodelling where the spongy bone is converted into compact bone
- Slow process
What are the factors that affect bone growth
- Adequate minerals (Ca, P, and Mg)
- Vitamins A,C and D
- Several hormones ( human GH, Insulin Growth factor, thyroid)
- Weight bearing exercise
Describe the bone’s role in calcium homeostasis
1) Some stimulus disrupts homeostasis by decreasing blood Ca2+ level
2)Parathyroid gland cells detect this (receptors)
3) This causes an increased production of cyclic AMP (control centre)
4) PTH gene turned on
5) Increased release of PTH
6) Effectors - osteoclasts increase bone resorption
Kidneys retain CA2+ in blood & produce calcitriol
7) Increase in blood CA2+ level
What happens to bone tissue during exercise
- Bone tissue alters its strength in response to mechanical stress
- Bone strength is increased as mechanical stress increases deposition of mineral salts and production of collagen fibres
- Removal of mechanical stress weakens bone through demineralisation and collagen fibre reduction
What are the common bone disorders
1) osteoporosis - porous bones due to depletion of calcium in the body
2) rickets & osteomalacia - disorders where bone calcification fails
3) herniated disc
4) hip fracture
What is an isotope bone scan
- radioactive tracer
- tracer uptake related to blood flow to the bone
- hot spots = increased uptake indicating bone cancer, abnormal healing of fracture or abnormal bone growth
- cold spots = degenerative bone disease, decalcified bone, fractures etc
How many bones are there in total and what are axial and appendicular bones
206 in total
Axial: bones that lie around the longitudinal axis of the body (80)
Appendicular: consists of the bones of the girdles and upper & lower limbs
What do the 8 cranium bones in the skull do?
Encloses and protects the brain
What do inner and outer surfaces of the skull do?
Inner surface: attach membranes that stabilise position of the brain, blood vessels and nerves
Outer surfaces provide area for attachment to muscle for head movement
