Bone Tissue

Trabeculae support & protect what?

Red bone marrow

Calcification is initiated by what cells?

bone building osteoblasts

Which bone minerals are stored & release for homeostasis?

Calcium, Phosphorous, Magnesium

Osteocyte

Maintains bone tissue

Monocyte

Type of white blood cell

What types of cartilage lack perichondrium?

Fibrocartilage and Articular cartilage

The areas between osteons contain ___________ (fragments of older replaced osteons).

Interstitial lamellae

Areas between osteons contain ________ _________. ISL are fragments of older osteons that have been partially destroyed during bone rebuilding or growth.

Interstitial lamellae (lacunae with osteocytes & canaliculi)

Osteocytes (bone cells)

Mature bone cells that maintain daily metabolism and no longer secrete matrix. Do NOT undergo cell division.

Both types of bone formation begin with what type of cell?

Mesenchymal cells

What type of cell becomes osteoblasts which form bone?

Mesenchymal cells

What type of cell transforms into chondroblasts which form cartilage?

Mesenchymal cells

Embryonic connective tissue begins as what?

Mesenchyme

Stress Fracture

Microscopic fissures from repeated strenuous activities

Endosteum

Thin membrane that lines the medullary cavity. Vascular layer contains a single layer of bone-forming cells & a small amount of connective tissue.

Periosteal arteries & nerves enter diaphysis how?

Through many perforating Volkmann's canals

Function of compact bone

To protect and support, it resists stress produced by weight and movement.

Periosteum

Tough sheet of dense irregular connective tissue rich in blood vessels and nerve fibers. Bone forming cells of periosteum enable bone to grow in thickness.

__________ of spongy bone are precisely arranged along lines of stress, helps bones resist stresses and transfer force without braking. Spongy bone tissue tends to be located where bones are not heavily stressed or where stresses are applied from many directions.

Trabeculae

Consists of lamellae arranged in a irregular lattice of thin columns called __________. With in each ___________ are lacunae that contain osteocytes. Canaliculi radiate outward from lacunae. Osteocytes of _______ ________ are located superficial surface of Trabeculae. Receive nourishment directly from blood circulating through medullary cavities.

Trabeculae, Trabeculae, Spongy bone,

What is yellow bone marrow?

Triglyceride storage-mainly adipose cells.

Triglyceride is found where and used for what?

Triglycerides stored in yellow bone marrow is used for potential chemical energy reserve.

*Troponin

Troponin, or the troponin complex, is a complex of three regulatory proteins that is integral to muscle contraction in skeletal muscle and cardiac muscle, but not smooth muscle.

Bone growth in length 4 zones at the epiphyseal plate

Zone of resting cartilage Zone of proliferating cartilage Zone of hypertrophic cartilage Zone of calcified cartilage

Osteogenic cell

Develops into an osteoblast

*Hematoma

A solid swelling of clotted blood within the tissues.

Lacunae contain what?

Osteocytes

*Calcitriol

A form of Vitamin D.

Osteogenic sarcoma (sarcoma= connective tissue tumor) Osteomyelitis (myel/o=marrow/spinal cord) Osteopenia (penia=deficiency)

-Bone cancer that mostly affects osteoblasts. -Infection of bone characterized by high fever, sweating, chills, pain, nausea, pus formation, edema, & warmth over affected bone & rigid overlying mm. (often caused by bacteria staphylococcus through openings from outside the body) fracture, wound, surgical procedure. -Reduced bone mass d.t. decrease in rate of bone synthesis to a level too low to compensate for normal bone resorption; V in bone mass below normal =osteoporosis

Gigantism Pituitary dwarfism Acromegaly

-Over secretion of hGH -Undersecretion of hGH -Over secretion of hGh during adulthood (bones of hands, feet, & jaw thickens & other tissues enlarge, eyelids, lips, tongue & nose enlarge, skin thickens & develops furrows, especially forehead & soles)

Epiphyseal line

At age 18-21, bone stops growing in length & cartilage in epiphyseal plate is replaced by _________________.

Endochondral ossification

1. Development of cartilage model: mesenchymal cells develop into chondroblasts, which form the cartilage model. 2. Growth of cartilage model: growth occurs by cell division of chondrocytes. 3. Development of primary ossification center: in this region in the diaphysis bone tissue replaced most of the cartilage. 4. Development of the medullary (marrow) cavity: bone break down by osteoclasts forms the medullary cavity. 5. Development of secondary ossification centers: these occur in the epiphyses of the bone. 6. Formation of articular cartilage & epiphyseal plate: both structures consist of hyaline cartilage.

Intramembranous ossification

1. Development of ossification center: osteoblasts secrete organic extracellular matrix. 2. Calcification: calcium & other mineral salts are deposited & extracellular matrix calcifies (hardens). 3. Formation of Trabeculae: extracellular matrix develops into trabeculae that fuse to form spongy bone. 4. Development of the periosteum: mesenchyme at the periphery of the bone develops into the periosteum.

Appositional growth (bone growth in thickness)

1. Ridges in periosteum create groove for periosteal blood vessel. 2. Periosteal ridges fuse, forming an endosteum-lined tunnel. 3. Osteoblasts in endosteum build new concentric lamellae inward toward center of tunnel, forming a new osteon. 4. Bone grows outward as osteoblasts in periosteum build new circumferential lamellae. Osteon formation repeats as new periosteal ridges fold over blood vessels.

Functions of Bone Tissue

1. Supports soft tissue & provides attachment for skeletal muscle. 2. Protects internal organs. 3. Assists in movement along with skeletal mm. 4. Stores & releases minerals. 5. Contains red bone marrow, which produces blood cells. 6. Contains yellow bone marrow, which stores triglycerides (fats), a potential chemical energy reserve.

Composition of bone matrix

25% water, 25% collagen, 50% crystallized mineral salts

Development Anatomy 5th, 6th, 7th, 8th wk

5th wk =limb bud appears as mesoderm covered with ectoderm 6th wk =constriction produces hand or foot plate & skeleton now totally cartilaginous 7th wk =endochondral ossification begins 8th wk =upper & lower limbs appropriately named

Closed reduction

=Restores pieces to normal position by manipulation.

Open reduction

=Surgery

*Fibroblasts

A cell in connective tissue that produces collagen and other fibers.

Periosteal

A dense layer of vascular connective tissue enveloping the bones except at the surfaces of the joints.

zone of calcified cartilage

A few cells thick (mostly of dead chondrocytes due to calcification of extracellular matrix), osteoclasts dissolve the calcified cartilage, osteoblasts & capillaries from the diaphysis invade the area. Osteoblasts laydown bone as a result, the zone of calcified cartilage becomes "new diaphysis", this is the only way that the diaphysis can increase in length

*Parathyroid

A gland next to the thyroid that secretes a hormone (parathyroid hormone) that regulates calcium levels in a person's body.

*Somatotropin

A growth hormone secreted by the anterior pituitary gland.

*Calcitonin

A hormone secreted by the thyroid that has the effect of lowering blood calcium.

Epiphyseal (growth) plate is ?

A layer of hyaline cartilage that lets the diaphysis of the bone grow in length.

What is Osteoporosis & what helps prevent it?

A medical condition in which the bones become brittle and fragile from loss of tissue, typically as a result of hormonal changes, or deficiency of calcium or vitamin D. Weight bearing exercise helps prevent osteoporosis (building bone mass; walking, weightlifting)

*Mitosis

A method of cell division, in which the nucleus divides into daughter nuclei, each containing the same number of chromosomes as the parent nucleus Compare prophase, metaphase, anaphase, telophase, meiosis

*Hydroxyapatite

A mineral of the apatite group that is the main inorganic constituent of tooth enamel and bone.

*Callus

A thickened and hardened part of the skin or soft tissue, especially in an area that has been subjected to friction.

*Mitosis

A type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth.

*Phagocyte

A type of cell within the body capable of engulfing and absorbing bacteria and other small cells and particles.

Composition of the matrix contains?

Abundant mineral salts (mostly hydroxyapatite) & collagen fibers.

How to prevent or decrease severity of Osteoporosis.

Adequate diet, weight-bearing exercise, & estrogen replacement therapy (for menopausal women). Behavior when young may be most important factor.

Factors Affecting Bone Growth -Nutrition

Adequate levels of minerals & vitamins. Calcium & phosphorus for bone growth. Vitamin C for collagen formation. Vitamins K & B12 for protein synthesis.

Gap Junctions

Allow cells to communicate.

__________ in bone or any other connective tissue secrete extracellular matrix. __________ in bone, or any other tissue, maintain the tissue. __________ in bone break down extracellular matrix.

Blasts, Cytes, Clasts,

Osteoblasts (bone buds)

Bone building cells, do Not divide, make & secrete collagen fibers that form extracellular matrix of bone tissue. They initiate calcification. As osteoblasts surround themselves with matrix, they become trapped in their own secretion and become osteocytes.

Osteogenic sarcoma (=connective tissue tumor) Osteomyelitis (myelo=marrow/ spinal cord, it is=inflammation) Osteopenia (=deficiency)

Bone cancer that primarily affects osteoblasts. Infection of bone w/ high fever, sweating, chills, pain, nausea, pus formation, edema, & warmth of affected bone & rigid overlaying mm. (often caused by bacteria from outside the body)

Aging & Bone Tissue

Bone density loss with age. Demineralization = loss of minerals (women rapid 40-45 as estrogen levels v) (males after 60). V of calcium from bones d.t. reduced osteoblast activity. V in extracellular matrix protein (mostly collagen fibers) growth synthesis. V in collagen production which gives bone tensile strength, bone becomes brittle & susceptible to fracture

What happens to bone without mechanical stress (lack of exercise). ex: reduced activity (cast), bedridden

Bone does not remodel normally because bone resorption occurs more quickly than bone formation.

Endochondral Ossification

Bone formation w/in hyaline cartilage that develops from mesenchyme.

Intramembranous Ossification

Bone formation w/in mesenchymal cells -arranged in sheet like layers that resemble membranes.

Appositional Growth (bone growth in thickness)

Bone grows in thickness or diameter d.t. addition of new bone tissue by periosteal osteoblasts around outer surface of bone. Periosteum cells differentiate into osteoblasts, which serve matrix. They develop into osteocytes & create ridges w/ room for blood vessels. Periosteum now becomes the endosteum that lines the tunnel. Concentric lamellae are formed by secreting osteoblasts & a new osteon is created. Osteoblasts under periosteum deposit new outer circumferential lamellae, further ^ thickness as additional periosteal become enclosed, the growth process continues. New bone is deposited on outer surface. The bone tissue lining the medullary cavity is destroyed by osteoclasts in the endosteum. The medullary cavity enlarges as the bone ^ in thickness.

Diaphysis

Bone shaft or body.

Mesenchymal cells (development of bone tissue)

Both types of bone formation begin with mesenchymal cells. Mesenchymal cells transform into chondroblasts which form cartilage. Mesenchymal cells become osteoblasts which form bone.

Endochondral Ossification -Step 5. Development of the secondary ossification centers.

Branches of the epiphyseal artery enter the epiphyses. Secondary ossification centers develop. Bone formation is similar to that in primary ossification centers. One difference: Spongy bone remains in the interior of the epiphyses. In contrast to primary ossification, secondary ossification proceeds outward from the center of the epiphysis toward the outer surface of the bone.

Comminuted Fracture

Broken ends of bones are fragmented

Rickets

Calcium salts are not deposited properly. Bones of growing children are soft. Bowed legs, skull, rib cage, & pelvic deformities result.

Skeleton is reservoir of _________ & __________

Calcium, Phosphate

What radiates outward from lacunae?

Canaliculi

How can changes in blood level of Calcium (Ca2+) be deadly? (plasma level < > 9-11mg/100ml)

Cardiac arrest if too high Respiratory if too low

Epiphyseal plate (cartilage growth plate)

Cartilage cells are produced by mitosis on epiphyseal side of plate. Cartilage cells are destroyed & replaced by bone on diaphyseal side of plate. 18-25 epiphyseal plate closes. Growth in length stops age 25. Cartilage cells stop dividing & bone replaces the cartilage (epiphyseal line)

Epiphyseal plate or cartilage growth plate

Cartilage cells are produced by mitosis on epiphyseal side of plate. Cartilage cells are destroyed & replaced by bone on diaphyseal side of plate. 18-25 epiphyseal plate closes, growth in length stops. Cartilage cells stop dividing & bone replaces the cartilage (epiphyseal line).

*Fibrocartilagenous

Cartilage that contains fibrous bundles of collagen, such as that of the intervertebral disks in the spinal cord.

Skeleton tissues.

Cartilage, bone tissue, epithelium, nerve, blood forming tissue, adipose tissue, dense connective tissue.

*Chondroblasts

Chondroblasts, or perichondrial cells, is the name given to mesenchymal progenitor cells which, from endochondral ossification, will form chondrocytes in the growing cartilage matrix. These cells are extremely important in Chondrogenesis due to their role in forming both the Chondrocytes and cartilage matrix which will eventually form cartilage. Chondroblasts are called Chondrocytes when they embed themselves in the cartilage matrix, consisting of proteoglycan and collagen fibers, until they lie in the matrix lacunae. Once they embed themselves into the cartilage matrix, they grow the cartilage matrix by growing more cartilage extracellular matrix rather than by dividing further.

Lamellae that encircle the bone just beneath the periosteum or encircle the medullary cavity are called _________ _________.

Circumferential lamellae

Found beneath the periosteum. BV, lymphatic vessels & nerves penetrate __________ bone through transverse perforating _______ _________. These connect with those of the _________ ________, periosteum & central or _________ __________. Central canals run longitudinally through the bone. Around the central canal are _______ __________ rings of calcified extracellular matrix. Between the lamellae are small spaces called, which contain osteocytes. Radiating in all directions from the lacunae are tiny ___________ filled with extracellular fluid.

Compact (dense) bone tissue, Volkmann's canals, Medullary cavity, Haversian canals, Concentric lamellae, lacunae, Canaliculi

Osteons

Components of compact bone tissue arranged into repeating structural units, aligned in same direction along lines of stress, e.g. In the shaft, they are parallel to the long axis of the bone.

Lamellae

Concentric rings of calcified extracellular matrix around the central canals.

Triglyceride storage (yellow bone marrow)

Consists manly of adipose cells, which store triglycerides. Stored triglycerides are a potential chemical energy reserve.

Compact Bone Tissue

Contains few spaces, strongest form of bone, found beneath periosteum of all bone, makes up shaft of long bone.

Repair of a Fracture -Step 1 Formation of Fracture Hematoma Formation of Fibrocartilagenous callus formation

Damaged blood vessels (BV) clot in 6-8 hrs, bone cells die. Inflammation brings in phagocytic cells for clean-up duty. New capillaries grow into damaged area. Fibroblasts invade the procallus & lay down collagen fibers. Chondroblasts produce fibrocartilage to span the broken ends of the bone.

Osteogenic Cells

Derived from mesenchyme cells, un-specialized stem cells, bone producing cells that divide to replace themselves. Only bone cells to undergo (cell division) and become osteoblasts. Found along inner portion of periosteum, in the endosteum, & in the canals with in bone that contain blood vessel.

Bone scan

Diagnostic procedure -small amount of radioactive tracer compound injected intravenously, degree of uptake is related to amount of blood flow to a bone. Scanning device (gamma camera) measures radiation emitted from bone, info. is translated to a photograph read like an x-ray on a monitor. (bone density screening -important osteoporosis)

7 parts of a long bone

Diaphysis, Epiphyses, Metaphysis, Articular Cartilage, Periosteum, Medullary (marrow) cavity, Endosteum.

Long Bone Structure

Diaphysis-bone shaft Epiphysis-proximal & distal end Metaphysis -neck of the bone Periosteum -hard tissue surrounding the bone (rich in nerve endings -plays important role in recovery) Marrow cavity -hollow, spongy part of the bone Endosteum -membrane surrounding marrow cavity

Periosteum cells __________ into __________, which secrete __________. They _________ into __________ & create __________ with room for the _________ ___________. Periosteum then becomes the __________ that lines the ___________.

Differentiate, Osteoblasts, Matrix, Develop, Osteocytes, Ridges, Blood vessels (BV), Endosteum, Tunnel

Epiphysis

Distal & proximal ends.

Pott's Fracture

Distal fibular fracture

Colles's

Distal radial fracture

Spongy (Cancellous) bone tissue

Does NOT contain Osteons, contains Trabeculae (little beams)

Factors Affecting Bone Growth -Sufficient levels of specific hormones

During childhood need insulin like growth factor. Promotes cell division at epiphyseal plate. Need hGH (growth), thyroid (T3&T4) & insulin.

What type of cartilage can perichondrium be found around the perimeter?

Elastic cartilage & Hyaline cartilage.

Triglyceride (Fat) Storage

Energy reserve (in yellow bone marrow)

Included in the metaphysis of growing bones

Epiphyseal plate - growth plate

Organic collagen fibers provide bones _____________.

Flexibility

Fracture (break in bone) involves?

Formation of a fracture hematoma, a fibrocartilaginous callus, & a bony callus, and bone remodeling.

Endochondral Ossification

Forms all bones except skull, mandible, jaw, clavicle, babys "soft spots-formation of bone within hyaline cartilage

Osteoblast

Forms bone matrix

Intramembranous Ossification

Forms the skull, mandible, jaw, clavicle, babys "soft spots-forms directly from mesenchymal cells

Osteoclast

Functions in resorption, the brake down of bone matrix

*Human Growth Hormone (hGH)

Growth hormone, also known as somatotropin, is a peptide hormone that stimulates growth, cell reproduction, and cell regeneration in humans and other animals. It is thus important in human development. It is a type of mitogen which is specific only to certain kinds of cells. Growth hormone is a 191-amino acid, single-chain polypeptide that is synthesized, stored, and secreted by somatotropic cells within the lateral wings of the anterior pituitary gland.

Interstitial growth

Growth in length from continual cell division of chondrocytes & secretion of matrix

Appositional growth

Growth in thickness from addition of extracellular matrix to the periphery

Factors Affecting Bone Growth -Sex steroids at puberty

Growth spurt & closure of the epiphyseal growth plate. Estrogens promote female changes-wider pelvis.

Mineralization (Calcification) is what?

Hardening of tissue when mineral crystals deposit around collagen fibers.

Spongy bone spaces vs compact bone spaces

Has many spaces vs very few spaces for vessels & bone marrow

Fracture (break) in a bone Is healing faster in bone than cartilage, and why?

Healing is faster in bone than cartilage d.t. lack of blood vessels (BV) in cartilage. Healing of bone is slow process d.t. vessel damage.

Blood cell production

Hemopoiesis (blood making) of platelets, red & white blood cells (occurs in red bone)

Spongy bone tissue & red marrow is found where?

Hip bones, Ribs, Breastbone, Vertebrae, Ends of some Long bones

(Perforating) Volkmann's Canals

Horizontal channels for blood vessels, lymphatic vessels and nerves.

Osteoclasts (bone barkers)

Huge cells formed from fused monocytes (type of White blood cell), break down bone (resorption) to allow for growth, maintenance and repair of bone, resorption occurs at surfaces such as endosteum. Here cell releases lysosomal enzymes & acids that digest protein & mineral components of extracellular matrix.

Endochondral Ossification -Step 6. Formation of articular cartilage & the epiphyseal plate

Hyaline cartilage that covers the epiphyses becomes articular cartilage. Between the diaphysis & epiphyseal (growth) plate, which is responsible for the lengthwise growth of long bones. When bone stops growing it becomes a thin plate.

Inorganic mineral salts are made of what minerals?

Hydroxyapatite (calcium phosphate) & Calcium carbonate

*Mitosis

In cell biology, mitosis is a part of the cell cycle when replicated chromosomes are separated into two new nuclei. In general, mitosis is preceded by the S stage of interphase and is often accompanied or followed by cytokinesis, which divides the cytoplasm, organelles and cell membrane into two new cells containing roughly equal shares of these cellular components. Mitosis and cytokinesis together define the mitotic phase of an animal cell cycle—the division of the mother cell into two daughter cells genetically identical to each other

Matrix of bones is made of what, which provides bone's ______________.

Inorganic mineral salts provide bone's hardness, Hydroxyapatite (calcium phosphate) & Calcium carbonate

Two methods of bone formation?

Intramembranous Ossification, Endochondral Ossification

Ossification (ossi=bone, fication=making) = Osteogenesis What are two methods of bone formation?

Intramembranous ossification (within=membrane) bone forms directly from mesenchymal cells arranged in sheet like layers that resemble membranes. Endochondral ossification (within=cartilage) bone forms within hyaline cartilage that develops from mesenchyme.

Primary Ossification Center of a Long Bone is where & what happens at this site?

Is in the diaphysis. Cartilage degenerates, leaving cavities that merge to form medullary cavity. Osteoblasts lay down bone. Next, ossification occurs in the epiphyses, where bone replaces cartilage, except for epiphyseal plate.

Bone is considered a connective tissue because .................?

It consists of widely separated cells surrounded by large amounts of extracellular matrix.

Medullary Cavity

Known as marrow cavity, contains fatty yellow bone marrow in adults. W/in the diaphysis.

Within each trabecula are _______ that contain ________.

Lacunae, Osteocytes

Trabeculae (little beams)

Lamellae arranged in an irregular lattice of thin columns, like scaffold to support compact bone along lines of stress, may be filled with red bone marrow.

zone of hypertrophic cartilage

Large, maturing chondrocytes arranged in columns.

Calcium Ions are involved in body systems how?

Nerve & mm cell function Blood clotting Enzyme function in many biochemical reactions

Osteomalacia

New adult bone produced during remodeling fails to ossify. Hip fractures are common.

Closed Fracture

No break in skin

Nutrient artery passes through what?

Nutrient foramen

Homeostasis Bones Role in Blood Calcium Regulation

Nutrition important to bone health. Each night we deposit minerals in our bones, that are stored for use by the rest of the body. Mineral supply needs to be replenished equally or faster to prevent osteoporosis.

Bone Remodeling

Ongoing process -osteoclasts carve out small tunnels in old bone tissue & then osteoblasts rebuild it. Osteoclasts release enzymes & acids that degrade collagen fibers & dissolve mineral salts. Dietary minerals -calcium, phosphorus, vitamin C, K, B12 needed for bone growth & < >. Insulin-like growth factor (IGFs) Human Growth Hormone, thyroid hormones, estrogens & androgens stimulate bone growth. Sex hormone slow resorption of old bone & promote new bone deposition.

Bone Remodeling

Ongoing since osteoclasts carve out small tunnels & osteoblasts rebuild osteons. Osteoclasts form leak-proof seal around cell edges. Secrete enzymes & acids beneath themselves. Release calcium & phosphorus into interstitial fluid. Osteoblasts take over bone rebuilding. Continual redistribution of bone matrix along lines of mechanical stress. Distal femur is fully remodeled every 4 month.

Bone is made of what tissues?

Osseous tissue (bone), cartilage, dense connective tissues, epithelium, adipose tissue, & nervous tissue.

The process by which bone forms?

Ossification (osteogenesis)

How does Ossification (osteogenesis) begin?

Ossification begins when mesenchymal cells become transformed into osteogenic cells. They undergo cell division & give rise to cells that differentiate into osteoblasts, osteoclasts & osteocytes.

Bone building cells. Synthesize & secrete collagen fibers & other organic compound needed to build extracellular matrix of bone tissue. They initiate calcification as _________ surround themselves with extracellular matrix they become trapped in their own secretions and become osteocytes.

Osteoblasts

Repair of a Fracture -Step 2 Formation of Bony Callus Bone Remolding

Osteoblasts secrete spongy bone that joins 2 broken ends of bone. Lasts 3-4 month. Compact bone replaces the spongy in the bony callus. Surface is remodeled back to normal shape.

Concentric lamellae are formed by secreting ________ and a new _______ is created. Osteoblasts under the __________ deposit new outer circumferential__________, further increasing the thickness. As additional periosteal blood become enclosed, the growth process continues. New bone tissue is deposited on the outer surface. Bone tissue lining the ________ _________ is destroyed by _________ in the _________. The ________ cavity enlarges as the bone increases in thickness.

Osteoblasts, Osteon, Periosteum, Lamellae, Medullary cavity, Osteoclasts, Endosteum, Medullary

Derived from fusion of many monocytes (white blood cell). Concentrated in the endosteum. On side of the cell that faces the bone surface, the plasma membrane of __________ is deeply folded into a ruffled border. Here cell releases lysosomal enzymes & acids that digest protein & mineral components of extracellular matrix. Brake down of bone (RESORPTION) part of normal growth & bone repair. Regulates blood calcium level.

Osteoclast

Are mature bone cells, & main cell in bone tissue. < > tissue & daily metabolism (exchange of nutrients & wastes) with in blood. DO NOT undergo cell division (divide)

Osteocytes

Are unspecialized stem cells derived from mesenchyme, the tissue from which almost all connective tissue originally formed. Only bone cells to undergo cell division; resulting cells develop into osteoblasts. Found along inner portion of periosteum, in endosteum & in canals within bone that contain BV.

Osteogenic cells

4 principal types of cells in bone tissue

Osteogenic cells Osteoblasts (bone building cells) Osteocytes (< > daily activity of bone) Osteoclasts (bone-destroying cells)

Components of compact bone arranged into repeating structural units. Each ________ is a tubelike cylinder that consists of a central canal with its concentrically arranged lamellae, lacunae, osteocytes, & canaliculi. Aligned in the same direction along lines of stress. In shaft (Parallel to the long axis of the bone) as a result resists bending or fracture with considerable force.

Osteons (havarian systems)

Compact bone consists of ________. Lies on top of ________ ________ __________ in the _________.

Osteons (haversian system) w/ little spaces b/w them. Lies on top of spongy bone tissue in the diaphysis

Spongy bone does not contain _________. Consists of _________ surrounding many_________ _______ _______ filled spaces.

Osteons, Trabeculae, red bone marrow

Hormonal Abnormalities

Over secretion of hGH during childhood produces giantism. undersecretion of hGH or thyroid hormone during childhood produces short stature. Both men or women that lack estrogen receptors on cells grow taller than normal. Estrogen responsible for closure of growth plate

Hormonal Influences on Bone

Parathyroid hormone (PTH) is secreted if Ca2+ levels fall. PTH gene is turned on & more PTH is secreted by gland. Osteoclast activity ^, kidney retains Ca2+ & produces calcitriol (a form of vitamin D). Calcitonin hormone (regulates calcium levels) is secreted fro parafollicular cells in thyroid if Ca2+ blood levels get too high. Inhibits osteoclast activity. ^ bone formation by osteoblasts.

Resorption (brake down of extracellular matrix)

Part of normal development growth, maintenance, & repair of bone. Osteoclast helps regulate blood calcium level.

Greenstick Fracture

Partial fracture

*Peptide

Peptides are biologically occurring short chains of amino acid monomers linked by peptide bonds. The covalent chemical bonds are formed when the carboxyl group of one amino acid reacts with the amine group of another. The shortest peptides are dipeptides, consisting of 2 amino acids joined by a single peptide bond, followed by tripeptides, tetrapeptides, etc. A polypeptide is a long, continuous, and unbranched peptide chain. Hence, peptides fall under the broad chemical classes of biological oligomers and polymers, alongside nucleic acids, oligosaccharides and polysaccharides, etc.

Calcification

Process of laying down minerals which ossify or harden

Functions of Periosteum

Protects bone, assists in fracture repair, helps nourish bone tissue, attachment point for ligaments & tendons, cells of periosteum enable bone to grow in thickness.

Organic collagen fibers

Provide bones flexibility, their tensile strength resists being stretched or torn, remove minerals with acid & rubbery structure results.

Metaphysis

Region where diaphysis joins epiphyses in mature bone. In growing bone each metaphysis includes an epiphyseal growth plate that allows bone to grow in length.

*Tensile strength

Relating to the amount that something (such as a wire) can stretch or be stretched without breaking.

Osteon

Repeating structural units found in compact bone aligned along the lines of greatest stress (vertical alignment) -each compact bone has many osteon's that line up next to each other =dense structure

zone of resting cartilage

Scattered chondrocytes nearest the epiphysis, the cells do not function in bone growth, and anchor the epiphyseal plate to the epiphysis bone.

Bone Classification- Name shapes & locations.

Shape (long, short, sesamoin, & irregular) Location (axial or Appendicular)

Calcification

The process of laying down minerals which ossify (harden)

Spongy bone makes up most of the bone tissue of ?

Short, flat & irregular shaped bones, epiphyseal of long bones & narrow ridge around medullary cavity of diaphysis of long bones.

Open Fracture

Skin broken

zone of proliferating cartilage

Slightly larger chondrocytes arranged like stacks of coins, these divide to replace those that die at the diaphyseal side of the epiphyseal plate.

Canaliculi

Small channels (canals) with extracellular fluid that radiate from the lacunae that allow osteocytes to share nutrition and remove waste.

Lacunae (little lakes)

Small spaces between the lamellae which contain osteocytes.

Where does hemopoiesis occur in adults?

Spongy bone tissue & Red marrow in Hip bones, Ribs, Breastbone, Vertebrae, Ends of some Long bones

How does Spongy bone tissue different from compact bone tissue?

Spongy bone tissue is light, reduces over all weight of bone, so it can move easier when pulled by skeletal mm. Trabeculae of spongy bone tissue support & protect the red bone marrow. (spongy bone tissue in hip bones, ribs, breastbone, vertebrae, & ends of certain long bones where red bone marrow is stored &, thus where hemopoiesis (blood cell production) occurs in adults.

Intramembranous Ossification Step 1. development of ossification center Step 2. calcification Step 3. formation of trabeculae Step 4. development of periosteum

Step 1. Chemical messages cause the mesenchymal cells to cluster & differentiate into osteoblasts. (the site is called an ossification center) Osteoblasts secrete the organic extracellular matrix until they are surrounded by it. Step 2. Surrounded osteoblasts mature into osteocytes. they lie in lacunae & extend their narrow cytoplasmic processes into canaliculi, carrying out daily metabolism. calcium & other mineral salts are deposited & the matrix hardens (calcification) Step 3. As matrix forms, it develops into trabeculae. blood vessels grow into the spaces between the trabeculae. Connective tissue associated with the blood vessels differentiates into red bone marrow. Step 4. Mesenchyme condenses at the periphery of the bone & becomes periosteum. A thin layer of compact bone replaces the surface (spongy bone remains in the center). The newly formed bone is regularly, remodelled (destroyed & reformed) as the bone is transformed into its adult size & shape.

Endochondral ossification 6 steps?

Step 1. Development of the cartilage model Step 2. Growth of the cartilage model Step 3. Development of the primary ossification center Step 4. Development of the medullary (marrow) cavity Step 5. Development of the secondary ossification centers Step 6. Formation of articular cartilage & the epiphyseal plate

Endochondral Ossification -Step 1. Development of the cartilage model.

Step 1. Endochondral ossification -the replacement of cartilage by bone. Mesenchymal cells cluster due to chemical attraction once again & become chondroblasts (cartilage builders). They then arrange in the shape of the bone. a membrane called the perichondrium forms around the outside.

Endochondral Ossification -Step 2. Growth of the cartilage model

Step 2. Chondroblasts become buried in the cartilage extracellular matrix, & mature into chondrocytes. Growth in length is from continual cell division of chondrocytes & secretion of matrix called interstitial growth. Growth in thickness is from the addition of extracellular matrix to the periphery called appositional growth.

Endochondral Ossification -Step 3. Development of the primary ossification center

Step 3. Chondrocytes hypertrophy & the cartilage matrix calcifies. Some chondrocytes die due to poor nutrition circulation & lacunae form & cavities along with the periosteal capillaries grow into the disintegrating calcified cartilage, inducing growth of a primary ossification center. Here bone tissue will replace most of the cartilage. Osteoblasts deposit bone matrix over calcified cartilage, forming spongy bone trabeculae. Primary ossification spreads toward both ends of the cartilage model.

6 main functions of bone

Support, Protection, Assistance in movement, Mineral Storage, Blood cell production, Triglyceride storage.

Perichondrium What type of tissue is perichondrium and what does it consist of?

The perichondrium is a layer of dense irregular connective tissue that surrounds the cartilage of developing bone. It consists of two separate layers: an outer fibrous layer and inner chondrogenic layer. The fibrous layer contains fibroblasts, which produce collagenous fibers. The chondrogenic layer remains undifferentiated and can form chondroblasts or chondrocytes.

Endochondral Ossification -Step 4. Development of the medullary (marrow) cavity

The primary ossification center continues to grow osteoclasts breakdown some of the newly formed spongy bone trabeculae. The medullary (marrow) cavity in the diaphysis forms. Most of the wall of the diaphysis is replaced by compact bone.

Perforating (Sharpey's) Fibers

Thick bundles of collagen fibers that work to attach the periosteum to underlying bone.

Articular Cartilage

Thin layer of hyaline cartilage covering the epiphysis where the bone forms a joint, reduces friction, improves fit & absorbs shock at freely movable joints.

(Central) Haversian Canals

Vertical canals that connect with those of the medullary cavity.

Those at risk of Osteoporosis (v bone mass resulting in porous bones)

White, thin menopausal, smoking, drinking female with family history. Athletes who are not menstruating d.t. v body fat & v estrogen levels. People allergic to milk with eating disorders whose intake of calcium is too low.

Effects of Exercise on Bone

Within limits, bone tissue alters strength in response to changes in mechanical stress. Becomes stronger through increased deposition of mineral salts & production of collagen fibers by osteoblasts (bone building).

Where are osteogenic cells found?

Within the inner layer of the periosteum and endosteum.

Falling on an outreached hand.

Wrist, scaphoid bone, radius, humerus, & clavicle fracture. Where force ultimately ends, will determine location & extent of fracture.

BLASTS =

buds or spouts (blasts in bone or any other connective tissue secrete extracellular matrix)

Cytes =

cell (cytes in bone, or any other tissue <maintain the tissue)

Bones are made of _____ _____ & _____ _____.

collagen fibers, calcium salts

What does Red bone marrow consist of?

developing blood cells, adipocytes, fobroblasts and macrophages w/in a network of reticular fibers. Present developing bones of fetus and some adult bones (pelvic, ribs, breast bone, vertebrae, skull, ends of arm & thigh bones)

Canaliculi connect ________ with one another & with the central canal. Provides many routes for nutrients & oxygen to reach osteocytes & for removal of wastes.

lacunae

Diaphysis of a bone increases in ________ during interstitial growth, because of ______ ________in the epiphyseal plate.

length, cell division

Impacted Fracture

one side of fracture driven into the interior of other side

Bone functions

posture, mm attachment, protection, hematopoetic (creates blood cells)

Bone tissue consists of widely _______ ________ surrounded by large amounts of ________ _______.

widely separated cells surrounded by large amounts of extracellular matrix