week 3 Lesson 1- Bone Flashcards
What is the epiphysis
Regions at the end of the bone
Spongy bone converted to compact bone
What is the diaphysis
Middle region bone
What is the medullary cavity
Found in the diaphysis. Hollow part of the bone that contains bone marrow.
What is the epiphyseal line
Region where bone growth terminated in adolescence
What is the periosteum
Double layer membrane around outside of bone (except Cartilage)
Outer fibrous (dense irregular)
Inner osteopenia layer (osteoblasts)
What is the endosteum
A membrane that lines the inner surface of bone tissue
Name the 2 types of bone tissue
Compact (cortical)
Trabecular (spongy)
Describe compact bone tissue
Smooth and solid
Generally cylinder shaped
Describe trabecular bone tissue
Loght porous spongy and mesh like
Structurally similar to honeycomb
What makes up the % of the bone
Organic matrix- protein colllage. 10%
Mag, sodium and bicarbonate. Water 25%
Mineral calcium and phosphate 65%
Name the function and location of osteoblasts
Bone formation
Growing portions of bone, periosteum and endosteum
Name the function and location of osteocytes
Sense mechanical strain
Trapped in matrix
Name the function and location of osteoclasts
Born resorption
Bone surfaces and sites of old injured uneeded bone
What is bone subjected to
Mechanical stress or load from external forces.
Muscle contraction, impact lonading, gravitational forces
What can stress on the bone be
Compressive. Tensile.
What is WOLFS LAW
bone adapts to loads under which it is placed
Describe what happens in bone formation
Osteoblasts dominate
Bone becomes stronger- and eight bearing exercise
Responses to increase stress
What does resorption . Respond to
Decreased stress.
Osteoclasts dominate
Bones become weaker. (Disuse, immobilisation, microgravity)
How is bone constantly remodelled in adults
Older bone replaces by new bone to maintain functional properties
How often is Cory cal and spongy bone replaces
C- 10 years
S- 3-4 ywars
Describe the activation in bone remodelling
Hormonal or mechanical stress timulation detected by osteocytes
Describe the resorption in bone remodelling
Osteoclasts release acid and enzymes to break down bone, creating howships lacunae
Describe the reversal in bone remodelling
Osteoclasts die and osteoblasts precursors enter lacunae
Describe the formation in bone remodelling
Osteoblasts generate new osteoid. Some osteoblasts become buried to become osteocytes
Describe the termination/mineralisation in bone remodelling
Some osteoblasts die and some become osteocytes. Osteoid undergoes calcification
How does “coupled remodelling” occur. Describe this
Activities of daily living produce enough stress so formation and reabsorption are in balance.
Describe uncoupled remodelling
Stress is insufficient and reabsorption dominates and bone mass is loss
Id the stress increases in modelling, how does this affect bone
Formation dominates, bone mass increases
Describe the process of bone development and growth
1) Skelton starts as cartilage model in the womb
2) as it grows, cartilage becomes calcified in diaphysis
3) blood vessels grow in area, bringing nutrients, oxygen and new cells. Osteoblasts and osteoclasts. Osteoblasts convert calcified matrix to spongy bone
4) osteoclasts break down newly formed bone creating medullary cavity
5) new ossification centre develops at epiphysis. Step 1-4 repeat
6) epiphyseal plate develops and cartilage production here and at ends of bone matched by conversion to bone
