Flashcards in Chapter 6 - Skeletal: Bone Tissue Deck (87)
What tissues is bone composed of? (6 kinds)
1. Bone (osseous) tissue. 2. Cartilage
3. Dense connective tissue. 4. Epithelium
5. Adipose tissue. 6. Nervous tissue
What process does bone tissue continually engage in?
Remodelling - construction of new bone tissue and breaking down of old bone tissue
What are the six main functions of the skeletal system?
3. Assistance in movement
4. Mineral homeostasis (storage and release)
5. Blood cell production (red bone marrow)
6. Triglyceride storage (yellow bone marrow)
Describe the role of bones in blood cell production.
In certain bones, a connective tissue called red bone marrow produces red blood cells, white blood cells and platelets.
Which bones contain red blood marrow?
The hip (pelvic) bones, ribs, sternum (breastbone), vertebrae (backbone), skull and end of the bones in the humerus (arm) and femur (thigh) bones.
How do red bone marrow and yellow bone marrow differ in composition and function?
Yellow bone marrow consists mainly of adipose cells, which store triglycerides. The stored triglycerides are a potential chemical energy reserve. Red bone marrow produces red, white and platelet cells.
What 7 parts does a long bone consist of? Describe them.
1. Diaphysis - bones shaft or body
2. Epiphyses - proximal and distal ends of the bone
3. Metaphyses - between the diaphysis and epiphyses. Contains a growth plate (epiphyseal plate). When a bones ceases to grow in length, the growth plate is replaced with bone resulting in an epiphyseal line.
4. Articular cartilage - thing layer of hyaline cartilage covering the part of the epiphysis where the bone forms a joint with another bone.
5. Periosteum - tough connective tissue sheath. Some of the cells allow the bone to grow in width but not length. Protects the bone, assist in fracture repair, help nourish bone tissue and serves as an attachment point for ligaments and tendons.
6. Medullary cavity - a hollow cylindrical space within the diaphysis that contains fatty yellow bone marrow and numerous blood vessels
7. Endosteum - thin membrane that lines the medullary cavity. Contains a single layer of bone forming cells and small amount of connective tissue
Why is bone tissue classified as a connective tissue?
Contains an abundant extracellular matrix that surrounds widely separated cells. (15% water, 30% collagen fibres, 55% crystallized mineral salts.
What is hydroxyapatite?
When calcium phosphate is combined with calcium hydroxide to form crystals of hydroxyapatite
What is calcification?
As hydroxyapatite crystals form they combine with other minerals (such as calcium carbonate, magnesium, fluoride, potassium and sulfate). Then these mineral salts are deposited in the framework formed by the collagen fibres of the extracellular matrix, they crystallize and harden.
What bone building cells initialize calcification?
What does the bones hardness depend on? It's flexibility?
Hardness --> crystallized inorganic mineral salts
Flexibility --> collagen fibres, provide tensile strength
What four types of cells are present in bone tissue?
1. Osteogenic cells
What are osteogenic cells?
Unspecialized bone stem cells derived from mesenchyme, only bone cells that undergo cell division - resulting cells develop into osteoblasts. Found along inner portion of the periosteum, in the endosteum and in the canals within bone that contain blood vessels
What are osteoblasts?
Bone building cells. Do NOT undergo cell division.
Synthesize and secrete collagen fibres and other organic components needed to build the extracellular matrix.
As osteoblasts surround themselves with extracellular matrix, they become trapped and become osteocytes.
What are osteocytes?
Mature bone cells. Main cells in bone tissue.
Maintains daily metabolism, such as exchange of nutrients and wastes with the blood.
Do NOT undergo cell division
What are osteoclasts?
Are huge cells derived from the fusion of as many as 50 monocytes (at type of white blood cell) and are concentrated in the endosteum. These cells breakdown the extracellular matrix (resorption) as a normal part of development, maintenance and repair
What is compact bone tissue?
The strongest form of bone tissue b/c it contains few spaces.
Found beneath the periosteum of all bones and makes up the bulk of the diaphyses of long bones.
What structural unit make up compact bone tissue?
Osteons (harvsian systems).
Each osteon consists of concentric lamellae arranged around a central canal. (Resembles growth rings on a tree)
What are concentric lamellae?
Circular plates of mineralized extracellular matrix of increasing diameter, surrounding a small network of blood vessels, lymphatics and nerves located in the central canal.
What are lacunae?
Small spaces between the concentric lamellae, which contain osteocytes.
What are canaliculi?
Small channels radiating from the lacune, which are filled with extracellular fluid. Inside the canaliculi are slender finger like projections of osteocytes
What are interstitial lamellae?
Areas between neighbouring osteons.
Also have lacunae with osteocytes and canaliculi
Fragments of older osteons that have been partially destroyed during bone rebuilding or growth.
What are perforating canals?
Canals that allow blood vessels, lymphatic vessels and nerves from the periosteum to penetrate the compact bone
What are circumferential lamellae?
Arranged around the entire outer and inner circumference of the shaft of a long bone.
Developed during initial bone formation.
Connected to the periosteum by perforating fibres.
What is spongy bone tissue?
Always located in the interior of a bone, protected by compact bone.
Does not contain osteons.
Consists of lamellae arranged in an irregular pattern of thin columns of trabeculae.
Between the trabeculae are tiny spaces filled with red bone marrow or yellow bone marrow.
What does each trabeculae consist of?
Concentric lamellae, osteocytes that lie in the lacunae and canaliculi that radiate outward from the lacunae
How is spongy bone different from compact bone?
1. Spongy bone tissue is light
2. Trabeculae support and protect red bone marrow (where hemopoiesis occurs)
What are periosteal arteries?
Small arteries accompanied by nerves, enter the diaphysis through many perforating canals and supply the periosteum and outer part of the compact bone