Chapter 6- Bones & Bone Tissue Flashcards
The functions of the skeletal system
The functions of the skeletal system
- Support -maintain shape
- Protection- internal organs
- System of levers for movement (muscles “pull” against bone for movement)
- Hematopoiesis -production of blood cells,
- Fat storage-in adults
- Mineral storage- calcium ions & phosphate
- Acid-basic homeostasis
5 Bone Shapes
- Flat Bone: any bone that is broad, flat, & thin
Example: Sternum, Scapula, Cranial, rib - Long Bone: longer than it is wide
Example: humerus, tibia, Ulna, Clavicle, Metatarsal, Femur - Short Bone: about as wide as it is long
Example: carpal, metacarpal,
-Sesamoid Bones: round, flat & found encased within tendon.
Example: patella
- Irregular Bones: any bone that do not fall within any of the pervious categories
Example: sacrum, vertebra
Periosteum
composed of dense irregular collagenous connective tissue that is richly supplied with a lot of blood vessels & nerves
Diaphysis
the shaft of a long bone, marrow cavity
Epiphyses
the end of a long bone
Articular cartilage
the epiphyses (end of long bones) are covered w/ a thin layer of hyaline cartilage, which allow bones to rub together with reduced friction at joints
Marrow (medullary) cavity
the largely hollow interior portion of the diaphysis of a long bone
Compact bone
the hard, dense outer bone, composed of repeating units called osteons; provides weight-bearing strength
Spongy bone(cancellous)
inner, honeycomb-like bone, forms a framework of bony struts that allows it to resist forces in many directions & provides a place for the bone marrow to reside
Endosteum
thin vascular membrane; inner surfaces of spongy bone
Epiphyseal plates (growth plates)
a line of hyaline cartilage from which a long bone grows in length in children & adolescents
Epiphyseal lines
once adulthood is reached; the cartilage is replaced by osseous tissue. Once the epiphyseal plates “close”, the long bone can no longer grow in length
The purpose of red marrow…
responsible for producing blood cells; infants & young children contain mostly red bone marrow b/c their rapid rate of growth requires a constant supply of new blood cells.
- Children: red marrow everywhere
- Adults: Red marrow remains only in the bones of the pelvis, proximal femur, humerus, vertebrae, ribs, sternum, clavicle, & scapulae
The purpose of yellow marrow…
responsible for storing triglycerides; at about age 5 yellow marrow begins to replace some of the red bone marrow. By adulthood, most bone marrow in the body is yellow
General structure of other bone shapes (compact bone and diploe)
“sandwich” made of two thin layers of compact bone and a middle layer of spongy bone housing bone marrow.
-Dipole: the spongy bone in flat bones
Nutrient Arteries
bloods enter the bone via a small hole in the diaphysis
Periosteum
supplies bone with blood vessels & sensory nerve fibers
Components of bone
organic matrix, inorganic matrix, collagen fibers and bone cells (all three)
Organic matrix
ECM ingredients; collagen fibers, proteoglycans, glycoproteins, & bone specific proteins (holds water)
Inorganic Matrix
minerals; mainly calcium phosphate salts (calcium ions, phosphorus, bicarbonate, potassium, magnesium, sodium salts)
Bone cells
three types of cells; osteoblast (builds bone/immmature bone), osteocytes (mature bone), Osteoclast (breakdown bone)
Osteogenic cells
stem cells that make osteoblasts & osteocytes (lacunae)
Macrophages
(immune cell) produce osteoclasts (acid & enzymes)
Ossification
the process of bone formation
-Bone formation begins at about 6 weeks of fetal development
Intramembranous ossification (membrane bone)
(membrane bone) bones build on starting material known as a model that is made of a membrane of embryonic connective tissue
Examples: skull & clavicle (flat bones)
Steps:
- Ossification centers- formation of primary woven between membranes
- Periosteum forms
- Formation of Compact bone plates
- New woven bone matures to spongy bone
Endochondral Ossification (cartilage bone)
(cartilage bone) bones build on a model made of hyaline cartilage; this results in a growth plate
o Examples: all the bones in the body below the head, except the clavicles
o Steps:
1. hyaline cartilage model is formed
2. bone collar & periosteum are formed around the shaft of the model
3. the primary ossification center is formed in the center of the diaphysis
4. the diaphysis is remodeled & the II ossification of epiphyses begins
5. the only cartilage remains at the articular surfaces & at the epiphyseal plate
Appositional Growth
growth in bone width
Interstitial Growth
increase in bone length; inside the tissue
Epiphyseal plate growth
Epiphyeal plate growth:
- Chondrocytes replicate & enlarge (more cells make more matrix)
- Cartilage plate grows, increasing bone length
- Cartilage dies & is replaced by bone
- Epiphyseal plate remains same size, while bone grows
Growth in Bone Length
Growth in Bone Length: structure of the epiphyseal plate
- Zone of reserve cartilage; resting zone (G0)
- Zone of proliferation; actively dividing
- Zone of hypertrophy & maturation; too little oxygen (start to die)
- Zone of calcification; dead chondrocytes
- Zone of ossification; bone cells moved in & made bone
Growth Hormone (GH)
produced by the anterior pituitary, an endocrine gland below the brain. Enhances protein synthesis and cell division. Infancy & childhood
- Increase rate of mitosis, promoting longitudinal growth
- Increases activity of osteogenic cells including their activity in the zone of ossification
- Direct stimulation of osteoblasts in periosteum, triggering appositional growth
Testosterone
male sex hormone
- Increase appositional growth (thinker)& great calcium salt deposits
- Increase rate of mitosis at the epiphyseal plate–>“growth spurts”
- Accelerates the closure of the epiphyseal plates
Estrogen
female sex hormone
- Increases rate of longitudinal bone growth & inhibits osteoclasts–>”growth spurt”
- Increase mitosis & osteogenesis
- Accelerates closure of epiphyseal plates, more potent effect –>women are shorter
Bone Remodeling
the continual process of bone growth & bone loss that takes place within healthy bone. Gives you mature bone.
- Causes: Stress (amount of compression), Tension (stretching force), Pressure (continuous downward force)
- Factors: stress, damage, nutrition, hormones, age
Bone Repair
replacement of primary bone with secondary bone
-Causes: damage
Parathyroid Hormone (PTH)
increases calcium ion level in blood
Calcitonin
produced by the cells of the thyroid gland, located in the anterior neck. Decrease blood calcium ion concentration by stimulating osteoblasts to build bone.
Triggers negative feedback loop when there is an increase in the number of calcium ions
Vitamin D
a steroid synthesized by the body in response to exposure of the skin to UV light; absorbed from the intestines
The process of fracture repair
4 Step:
- Blood clot formation (inflammation)
- Fibrous network forms a soft callus
- Osteoblasts enter the callus & begin cancellous bone formation
- The bone callus is remodeled & primary bone is replaced with secondary bone
Osteopetrosis
(marble bone disease) defective osteoclast that do not properly degrade bone
-disorders of the skeletal system
Osteoporosis
inadequate inorganic matrix in the ECM results in brittle bone
Achondroplasia
(dwarfism) defect in a gene that produces an abnormal growth factor receptor on cartilage
Gigantism
excess growth hormone secreted in childhood before closure of the epiphyseal plates
Acromegaly
excess GH secretion occurs after closure of the epiphyseal plates causes enlargement of bones
Hematopoiesis
formation of blood cells
Yellow marrow
contains adipocytes with stored triglycerides, used as fuel
Red marrow
site of production of blood cells
Long bones
longer than it is wide
Short Bones
about as wide as it is long
Flat bones
any bone that is broad, flat, & thin
Irregular bones
any bone that do not fall within any of the pervious categories
Sesamoid bones
round, flat & found encased within tendon.
Periosteum
composed of dense irregular collagenous connective tissue that is richly supplied with blood vessels & nerves
Endosteum
thin vascular membrane; inner surfaces of spongy bone
Diaphysis
the shaft of a long bone
Epiphysis
the end of a long bone
Medullary (marrow) cavity
the largely hollow interior portion of the diaphysis of a long bone
Articular Cartilage
the epiphyses (end of long bones) are covered w/ a thin layer of hyaline cartilage, which allow bones to rub together with reduced friction at joints
Cancellous (spongy) bone
inner, honeycomb-like bone, forms a framework of bony struts that allows it to resist forces in many directions & provides a place for the bone marrow to reside. Helps distribute stress.
Epiphyseal plate (growth plates)
a line of hyaline cartilage from which a long bone grows in length in children & adolescents
Epiphyseal line
once adulthood is reached; the cartilage is replaced by osseous tissue. Once the epiphyseal plates “close”, the long bone can no longer grow in length
Dipole
the spongy bone in flat bones
Osseous tissue (bone tissue)
primary tissue type found in bones
Hydroxyapatite Crystals
a calcium phosphate- base mineral that makes up the inorganic portion of the osseous tissue ECM
Osteoid
organic matrix of bone, consist of collagen and other proteins
Osteoblasts
build bone
Osteocytes
mature bone cells
Osteoclasts
breaks down bone
Osteoporosis
inadequate inorganic matrix in the ECM results in brittle bone
Osteon (haversian system)
compact bone, consist of concentric rings of bone matrix called lamellae that surround a central canal
Lamellae
the “rings” on the osteon, helps withstand a great deal of stress
Central Canal (Haversian canal)
runs in the center of each osteon, containing blood vessels, lymphatic vessels & nerves
Lacunae
small cavities that are filled w/ ECF & located between lamellae
Canaliculi
small channels thru which osteocytes communicate
Interstitial Lamellae
the matrix between individual osteons
Perforating Canal
connects central canals of neighboring osteons
Trabeculae
spicules of bone that make up spongy bone tissue
Ossification (osteogenesis)
the process of bone formation
Intramembranous Ossification
(membrane bone) bones build on starting material known as a model that is made of a membrane of embryonic connective tissue
Endochondral Ossification
(cartilage bone) bones build on a model made of hyaline cartilage; this results in a growth plate
Appositional Growth
growth in the width
Interstitial growth
growth in length
Chondrocytes
cells found in healthy cartilage
Growth hormone (GH)
produced by the anterior pituitary, an endocrine gland below the brain. Enhances protein synthesis and cell division. Infancy & childhood
Bone deposition
new bone is formed
Bone resorption
old bone is destroyed
Parathyroid Hormone (PTH)
increases calcium ions in blood
Calcitonin
produced by the cells of the thyroid gland, located in the anterior neck. Decrease blood calcium ion concentration by stimulating osteoblasts to build bone.
Vitamin D
a steroid synthesized by the body in response to exposure of the skin to UV light; absorbed from the intestines
Fracture
“broken bone”
Hematoma
“blood clot”, a mass of blood cells & proteins that resembles grape jelly
Soft Callus
(soft skin) mixture of hyaline cartilage & collagenous connective tissue
Bone Callus
(hard callus) osteoblasts within the periosteum begin laying down a collar of primary bone
