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Why are bones resilient?
because of their elastic protein matrix, and strong because of mineral salts deposited in this matrix
The 5 functions of the skeletal system are: ___________________
Support surrounding tissues
Protect vital organs
Provide levers for muscles to pull on generating movement
Manufactures blood cells (hematopoiesis)
Stores mineral salts (calcium, phosphorus) and fats
Environment in which bone develops in fetus
found at ends of bones and in joints
Provides smooth surface for bone to bone areas
Step 3: Broken Bones
Osteoclasts are present in bone cavities, derived from the immune system they cause bone reabsorbtion, and remodelling.
Step 4: Broken Bones
Osteoclasts remove bone from the inner side and so remodel bone as after a break and can make a crooked bone straight
The two types of ossification are: _______ and _______
(both result in cancellous and compact bone)
Maintaining Bone requires calcium whose concentration is controlled by 2 hormones of the endocrine system:
Dense connective tissue membrane is replaced by inorganic salts like calcium, forming bones.
This connective membrane becomes the periosteum, over a layer of compact and a layer of spongy bone.
Only cranial bones are formed this way, complete ossification of the skull is not complete until fontanels close after birth.
This is when bone develops inside cartilage environment.
Osteoblasts become completely surrounded by protein matrix and become mature bone cells or osteocytes
Produces all other bones of the body
forming new bones
By end of 3 months fetus skeleton is completely formed but mostly cartilage
Begins ossification and grows as osteoblasts invade cartilage
Dense and strong
Contain "Haversian canals"
Blood vessels run parallel to surface of the bone
These are surrounded by concentric rings of bone (lamella)
Between rings of bone are Lacunae cavities containing osteocyte connected to the central haversian canal by canaliculi.
Horizontal open areas contain blood vessels and fluid that nourish bone cells (osteocytes)
Functions of havesian cannals:
dense and strong with Haversian systems of central canals surrounded by rings of bone. Rings separated by lacunae, connected by canniculi. Horizontally blood vessels run through these canals bathing osteocyte with 02 and food, excreting waste
. Cancellous or spongy bone
Found at ends of long bones and forms the center of all other bones
Spongy appearance created by meshwork of bone (trabeculae) with spaces filled with bone marrow
What else does Cancellous bone do?
Function as open spaces where bone marrow filled with red bone marrow performs hemapoesis. In adults found in vertebrae, sternum, pelvis, end of humerus (upper arm) and femur (thigh). Areas decrease with age.
Red marrow whose functions is...
Hematopoiesis (formation of RBC, WBC & Platelets). Contains blood cells in all stages of development.
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