Bone Tissue & Microscopic Structure Flashcards
What makes bone a living tissue?
Cells
What do bone cells respond to?
External factors and trauma. If you use your body a certain way (sports) it will make slight adjustments to help with that. It responds to trauma to unite broken bits (that’s why good realignment is important)
What are the two extracellular components that bone has that makes it hard?
Organic = Organic molecules
Inorganic = Mineral (makes bones hard)
What percentage of the extra-cellular matrix (ECM) makes up the organic and inorganic sections on bones?
33% organic
67% inorganic
What makes up the organic percentage of the ECM?
Collagen and Ground substance (what the collagen sits in)
What makes up the inorganic percentage of the ECM?
Mineral component (not sure I need to know the names?)
What is the function of the organic percentage of ECM?
To resist tension (so that the bone is not brittle)
What is the function of the inorganic percentage of the ECM?
Makes the bone hard and resistant to compression
What are the names of the cells that make up the cellular component of the bone?
Osteoblasts, Osteocytes, Osteoclasts, Osteogenic cells (not important, turns into osteoblasts),
What do the three cells do?
Maintain the bones homeostasis by balancing the destruction and formation of bone so that the amount of bone stays the same
What is the function of osteoblasts?
Produce new bone matrix
What is the function of osteocytes?
Recycle protein and minerals from matrix
What is the function of osteoclasts?
To destroy bone matrix
The two types of bone tissue are made of the same thing but structured differently. What are the structures of both?
Osteon structure (compact)
Trabecular structure (cancellous)
What is the anatomy word for holes?
Foramina
What are osteons?
longitudinal unit within compact bone
What is the function of osteons?
to provide a pathway for nutrients to get to the cells in the ECM
What is the central canal?
A canal in the middle of an osteon that contains blood vessels and nerves
What are lamellae?
a series of cylinders formed of ECM around the central canal
What is the function of lamellae?
to form the shape of the osteon and the collagen fibres within the lamellae resist forces
What are lacuna?
Lakes for osteocytes
What are canaliculi?
channels for osteocytes through the extra-cellular matrix (ECM)
What are trabeculae?
Struts of lamella bone. Makes up the cancellous bone structure.
Where is bone marrow found in cancellous bones?
Within the cavities between trabeculae
Why does cancellous bone not have a central canal?
Because there are lots of gaps between trabeculae so it is easy for nutrients to get into the blood stream
Why trabecular bone?
It can take force from multiple directions, it directs the force from body weight in a single direction down the shaft and spreads it distally
How is weight transferred in the hip joint?
trabeculae channel weight around the ilia into femora
How do osteoblasts (formation) and osteoclasts (destruction) work together for bone formation?
Osteoblasts add bone matrix in lamellae to bone surface while osteoclasts remove bone matrix from medullary cavity.
What is bone homeostasis?
The balance of osteoblasts and osteoclasts activity
What does the fact that bone is constantly being destroyed/formed allow for? (called bone remodelling)
It allows the body to mobilise calcium, phosphate and other minerals from the bone matrix (the stuff that has been stored in the bone)
What does the bone remodelling process allow for?
allows bone to respond plastically and allows shape change through life to resist strain etc.
What happens if bone homeostasis isn’t maintained?
You can get an imbalance in osteoblastic and osteoclastic activity, which results in conditions like osteoporosis/osteopenia(less bad version of osteoporosis).
What does osteoporosis look like inside the bone?
Loss of cortical(compact) bone, in cancellous bone it results in trabeculae becoming thinner, compression fractures or vertebrae.
Causes of osteoporosis
Females = loss of oestrogen post-menopause, lifestyle factors (lack of excersise or certain nutrition).
What are the nutritional factors that potentially cause osteoporosis?
Lack of sleep, smoking, drinking, lack of calcium (milk), too much salt, menopause.
How does your starting point effect your risk of osteoporosis?
Peak bone mass in your 20’s and if this is already low then more likely to become osteoporotic, if you already exercise a lot your bones know they need to stay thicker/stronger.
