Chapter 6: The Skeletal System Bone Tissue Flashcards
Osteology
Study of bone structure and treatment
Long Bone
Has greater length than width.
Hemopeoesis
Production of RBC, WBC and platelets in red bone marrow.
Bone
Osseous tissue
Hydroxyapatite
Crystal formed from Calcium phosphate combined with calcium hydroxide
Calcification
Initiated by bone building cells called osteoblasts.
Compact bone
Strong form of bone tissue
Composed of osteons.
Contains: Lamellae, lacunae, canaliculi, osteocytes.
Lacunae
Contain osteocytes. Small spaces concentric lamella in compact bone.
Canaliculi
Are filled with extracellular fluid. Radiate in all directions from lacunae.
Interstitial Lamellae
Areas between neighboring osteons contain lamella
Transverse interostenic Canals
Blood vessels and nerves from the periosteum penetrates compact bone through this canal
Circumferential Lamellae
Lamellae arrange around outer and inner circumference of shaft of long bone.
External Circumferential Lamellae
Are directly deep to the periosteum
Perforating (Sharpey’s) Fibers
Connect external circumferential Lamellae (underlying bone) to periosteum. These fibers are thick bundles of collagen.
Internal Circumferential Lamellae
Lamellae that line the medullary cavity
Blood Vessels in Bone
Bone is rich in blood. Found in bone containing red bone marrow.
Ossification
Or osteogenesis
Process by which bone forms
Bone Remodeling
Ongoing replacement of old bone tissue by new bone tissue
Bone Resorption
The removal of minerals and collagen fibers from bone by osteoclast
Bone Deposition
Addition of minerals and collagen fibers to bone by osteoblasts
Parathyroid Hormone
PTH
Increases blood ca2+level
Secretion operates via neg feedback
Calcitriol
Active form of vitamin D. Promotes absorption of calcium rich foods from GI Tract into blood.
Calcitonin
CT
Secreted by thyroid gland
Inhibits activity of osteoclasts, speeds up Ca2+ uptake by bone and accelerates its deposition into bones.
Osteoprogenitor Cells
unspecialized bone stem cells. Derived from mesenchyme. Found in periosteum.
Osteoblasts
Bone building cells. Initiate calcification. Regulates calcium.
Becomes osteocytes when trapped in their own secretions.
Osteocytes
Mature Bone cell.
Main cell in bone tissue.
Osteoclasts
Carve out bound. Found in endosteum. Regulate calcium.
Bone Reabsortion
Breakdown of extracellular matrix in bone
Spongy Bone
Also known as: trabecular
Do not contain osteons
Found in interior of bones, protected by layer compact bone.
Consists of: trabeculae, Lamellae, lacunae, canaliculi
Trabeculae
Found in Spongy bone.
Lamellae arranged in irregular pattern of thin columns.
Vitamin A
Stimulates osteoblasts
Vitamin C
Synthesis collagen, main bone protein.
Vitamin D
Helps build bones by increasing absorption of Ca2+ from GI tract to blood.
Vitamin k, b12
Synthesis of Bone protein
Insulin Hormones
Most important: Insulin, from pancreases.
Promotes bone growth by increase synthesis of bone proteins.
Thyroid Hormones
T3, T4: promote bone growth by stimulating osteoblasts.
Sex Hormones
Estrogen and androgens: increases osteoblasts activity during puberty.
Skeletal System Basic Function
- Support: structural framework, supports soft tissue, provides attachment points for the tendons
- Protection: protects internal organs from injury.
- Assistance in movement: muscles attach to bones, when contracted pull bones to move.
- Mineral Homeostasis: stores minerals- Ca and PO4, contributes to bone strength and bone tissue stores calcium.
- Blood Cell Production: red bone marrow produces RBC, WBC and Platelets
- Triglyceride Storage: yellow bone marrow consists of adipose cells to store triglycerides (potential chemical energy).
Diaphysis
Shaft or body. Long cylindrical main portion of body.
Epiphyses
Growing over. Are the proximal and distal ends of bones
Metaphyses
Between the diaphysis and epiphyses. Contains Epiphyseal growth plate.
Epiphyseal Growth Plate
Layer of hyaline cartilage. Allows diaphysis of bone to grow in length.
Epiphseal Line
When bone ceases to grow in length, cartilage in place is replaced by bone.
Articular Cartilage
Thin layer of hyaline cartilage covers epiphysis where bone forms a joint with another bone.
Lacks perichondium and blood vessels.
Periosteum
Protection of bone, nourishment, repair and growth.
Connective tissue sheath associated with blood supply. Surrounds bone surface when not covered by articular tissue.
2 layers-
1. Outer fibrous layer: dense irregular CT
2. Inner osteopenia layer: cells
Medullary Cavity
Or marrow cavity
Hallow, cylindrical space within diaphysis. Contains fatty yellow bone marrow and blood cells.
Minimizes weight of bones.
Endosteum
Thin membrane, lines medullary cavity
Contains: single layer of bone forming cells and small amount of CT
Long Bone Layer from Outside to Inside
Diaphysis, periosteum, compact bone, endosteum.
Bone Cells in Order
- Osteoprogenitor cells
- Osteoblasts
- Osteocytes
- Osteoclasts
How is Spongy Bone different than Compact Bone
- Spongy bone is light, reduces weight of bone. Allows bone to move more readily when pulled by skeletal muscle
- The trabeculae support and protect the red bone marrow.
Periosteal Arteries
Enter diaphysis through interosteonic canals. Supplies periosteum and outer part of bone.
Nutrient Artery
Near the center of diaphysis. Passes though a hole called nutrient foramen.
Metaphysical Arteries
Enter metaphyses of long bone, together with nutrient artery supply red bone marrow and tissue of metaphyses.
Epiphyseal Arteries
Enter epiphyseal of long bone and supply red bone marrow and bone tissue of epiphyses.
Intramembranous Ossification
Bone formation of flat bones of skull, facial bones, mandible, clavicle and soft spots of fetal skull.
1. Development of ossification center
2. Calcification
3. Formation of trabeculae
4. Development of the periosteum
Endochondral Ossification
Replacement of cartilage of bone. Most bones are formed this way.
1. Development of the cartilage model
2. Growth of cartilage model
3. Development of the medullary cavity
4. Development of the secondary ossification centers
5. Formation of articular cartilage and epiphyseal growth plate
Growth in Length
Involves:
1. Interstitial growth of cartilage on epiphyseal side of plate
2. Replacement of cartilage on the diaphyseal side of plate
Red Bone Marrow
Found in CT. Produces RBC, WBC, and platelets.
Consists of: developing blood cells, adipocytes, fibroblasts, macrophages within a network of reticular fibers.
Yellow Bone Marrow
Stores triglycerides. Potential chemical energy.
Consists of: adipose cells