ANATOMY AND PHYSIOLOGY I
a growth hormone;
produced by the adenohypophysis (anterior pituitary), in response to the growth hormone-releasing hormone GH-RH
What are the 4 types of bone cells and what makes them different from one another?
1. Osteocytes-maintain protein and mineral content of the surrounding matrix by secreting chemicals that dissolve the adjacent matrix, and release minerals into circulation, then rebuild matrix by stimulating new deposits of hydroxyapatite crystals, ALSO participate in the repair of damaged bone if they are released from their lacunae which gives them the ability to convert to an osteoblast or osteoprogenitor
The breakdown of the mineral matrix of bone.
The endocrine gland whose lobes are lateral to the thyroid cartilage of the larynx.
A connective tissue containing specialized cells and a mineralized matrix of crystalline calcium phosphate and calcium carbonate - (CCP and CC); also called BONE.
A cell that produces the fibers and matrix of bone.
^Think of a blast in your head. It looks like a bunch of squiggly fibers like the way you'd draw a firework exploding, doesn't it? Now, just remember that the BLAST produced those FIBERS and also produced a movie, the MATRIX of bone. ^
What are the 5 primary functions of the skeletal system?
1. Support 2. Storage of Minerals and Lipids 3. Production of Blood Cells 4. Protection 5. Leverage
Microscopic passage ways BETWEEN cells
Bile canaliculi carry bile to bile ducts in the liver.
In bone, canaliculi PERMITS THE DIFFUSION of nutrients and waste TO and FROM OSTEOCYTES.
osteocytes (osteo-bone + cytes-cells)
mature bone cells that make up most of the cell population
each osteocyte occupies a lacuna *a pocket sandwiched between layers of matrix*
the basic FUNCTIONAL unit of mature compact bone, aka. the "Haversian sytem"
squamous stem cells that divide to produce daughter cells that differentiate into osteoblasts. Osteoprogenitor cells:
1. MAINTAIN POPULATIONS of OSTEOBLASTS
2. are CRITICAL in REPAIRING a FRACTURE
WHERE ARE THEY? located in the very inner, cellular layer of the periosteum called the ENDOSTEUM, which lines medullary cavities and line passageways containing blood vessels that penetrate the matrix of compact bone
Osteoclasts (osteo bone + clast break)
GIANT cells that Remove and Recycle bone MATRIX.
(derived from the same stem cells that produce monocutes and macrophages, they are NOT RELATED to other osteo-cells AND they function by secreting proteolytic (protein-digesting) enzymes to dissolve the matrix and release stored minerals....what is the name of the process again? OSTEOLYSIS (osteo- bone , lysis- loosening ) which makes sense since Osteolysis can be called an erosion process (as bone loosens, is disintegrates, and gets REABSORBED, which is important in the regulation of calcium and phosphate concentrations in body fluids.)
Osteoclasts vs. Osteoblasts
OsteoCLASTS are constantly REMOVING Matrix and OsteoBLASTS are constantly ADDING to Matrix
^ Easy Way to Remember: Clasts CUT and Blasts BUILD^
CONCEPT APPLICATION CHECK QUESTION:
How would the compressive strength of a bone be affected if the ratio of collagen to hydroxyapatite increased?
Hydroxyapatite composes about 2/3rds of bone tissue, and is made of calcium phosphate, ions, calcium carbonate, etc....it's strong but very brittle.The crystals are hard enough to withstand compression but are so brittle that they can SHATTER when exposed to sudden bending, twisting, or under the stress of a SUDDEN IMPACT. Collagen fibers, about 1/3 of bone weight, is the opposite. It is very flexible proving remarkably strong when twisting, bending, or in re: to tension (pulling). HOWEVER, exposed to simple COMPRESSION, collagen fibers simply BEND OUT OF THE WAY. SOOOO.....I would say that the compressive strength of a bone would be REDUCED if the Collagen to Hydroxyapatite Ratio Increased.