Chapter 6 Flashcards
bones or osseous tissue
BONE/OSSEUS TISSUE
WHAT IS IT, HOW IS IT MADE
connective tissue in which the matrix is hardened by calciumphosphate and other minerals
Diaphysis
the shaft of a bone (also called the Body)
Epiphysis
the end(s) of a bone
Articular (Hyaline) cartilage
covers the ends of moveable bones
Periosteum
fibrous membrane that covers the outer portion of a
bone, tendons attach here, highly innervated
Medullary (Marrow) cavity
space inside bone that contains marrow
Endosteum
the lining of the medullary cavity
Epiphyseal plate
area that contains hyaline cartilage in growing
bone, area that causes bone to elongate, becomes ossified (bone) in adults
Osteogenic cell
a stem cell that differentiates to become an
Osteoblast
Osteoblast
cells that lay down collagen fibers and matrix
to form bone
Osteocyte
mature osteoblast, bone cells, sense the various stressors on bone
Osteoclast
bone dissolving cells
Matrix
- mostly Hydroxyapatite, a calcium phosphate salt, and some calcium
carbonate - organic portion is mostly collagen
Compact bone
- densely packed bone, usually located in the outer diaphysis
Osteon = Haversian System is the
- the basic structural unit of compact bone
Central (Haversian) canal
located at the center of the Osteon, contains vessels and
nerves
Concentric lamellae
- concentric layers of matrix that surround the Central canal
Lacuna
the space that houses a osteocyte
Canaliculi
- “tiny canals” that connect lacuna
Perforating (Volkmann) canal
channels that contain vessels and nerves, connect adjacent osteons and osteons to the outer surface of bone
Spongy bone
loosely packed bone, usually found inside of the epiphysis
a. Trabeculae
- thin plates of calcified tissue that provide a lattice
appearance to spongy bone
Red Bone Marrow
hemopoietic tissue (produces formed elements of the blood,
ex. RBC, WBC, Platelets
Yellow Bone Marrow
Adipose tissue, not hematopoietic
Bone Developmentis is called
Ossification or Osteogenesis = formation of bone
- Two methods:
Intramembranous ossification produces
produces flat bones, ex. skull, clavicle
- bone develops from membranes
Endochondral ossification
produces most bones
- hyaline cartilage matrix is laid down initially, then
ossification occurs replacing this cartilage
Remodeling
The change of the size and shape of bones to accommodate the changing forces applied to the skeleton.
Interstitial growth
Adding matrix. When this occurs in the hyaline
cartilage of the epiphyseal plate, the bone grows in length.
Appositional growth
Deposition onto the surface of bone. Increases the
diameter of a bone.
Calcium and Phosphate Homeostasis.
Normal range of blood calcium = 9.2 to 10.4 mg/dL
Hypocalcemia
low blood calcium, muscle is unable to relax, tetany
Hypercalcemia
high blood calcium, nerves and muscles are slow
torespond; weakness, sluggish reflexes, poss. cardiacarrest
Calcitriol
a form of vitamin D, is stimulated by absorption of UV light
- this hormone raises blood calcium by:
a. Increasing absorption in the Small Intestine.
b. Stimulates calcium removal from bones (Osteoclast).
c. Causing the Kidney to retain calcium in the blood.
Calcitonin
released by the Thyroid gland
- this hormone lowers calcium level in the blood by:
a. Inhibiting Osteoclast.
b. Stimulate Osteoblast (places calcium into bone)
Parathyroid hormone (PTH)
this hormone raises the blood calcium level by:
a. Stimulating Osteoclast.
b. Causing the Kidneys to retain calcium in the blood.
c. Stimulates the production of Calcitriol.
d. Decreases Osteoblast activity.
Fracture
Any disruption in the continuity of a bone.
- During normal fracture repair, the bone forms a hard
callus that is often stronger than the original bone.
Steps associated with fracture repair, step 1
Hematoma forms around fracture site
Steps associated with fracture repair, step 2
Granulation tissue forms
- hematoma becomes infiltrated with capillaries, fibroblasts,
macrophages, osteoclasts, osteogenic cells
Steps associated with fracture repair, step 3
Callus formation
- fibroblasts lay down collagen, “soft callus” is formed
which is made up of fibrocartilage
Steps associated with fracture repair, step 4
Remodeling
- bone tissue is laid down replacing cartilage, this forms
the bony (hard) callus
- initially spongy bone is laid down, the outer portion of
the bone is converted (remodeled) into compact(cortical) bone
Osteoporosis
Loss of bone mass, making them more susceptible to
fracture. Associated with aging.
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