Chapter 6
Fracture Healing
1- Hematoma fill gaps 2 - Fibroblasts and chondroblasts infiltrate hematoma and a soft callus forms 3- osteoblasts build bone 4 - callus is remodeled and primary bone is replaced with secondary bone
Growth Hormones do what (3 things)
1- Increase cell division in chondroblasts 2- Increase activity of osteogenic cells 3- Directly stimulates osteoblasts
Summary of BONE CELLS
1- Osteogenic cells differentiate into osteoblasts 2- Osteoblasts deposit bone until they are trapped and become osteocytes 3- Osteocytes maintains bone ECM
Growth Hormone is secreted by which gland and does what
Anterior Pituitary Gland / Enhances protein synthesis
Growth in width is called
Appositional
By which process, as an individual grows to adulthood, is the thickness (diameter) of bone increased?
Appositional Growth
Which is the proper sequence of steps in the healing of a fracture (the steps are listed below but are not in the correct sequence of events):
1. osteoblasts form trabecular bone that joins together the fractured ends of the bone and bony callus replaces fibrocartilage callus 2. bone remodeling occurs and compact bone replaces the spongy bone around the periphery of the fracture site 3. fibroblasts and chondrocytes from the periosteum form the fibrocartilage callus 4. a fracture hematoma forms and bone cells in the region of the fracture die a) 4, 1, 2, 3 b) 4, 3, 1, 2 c) 4, 2, 3, 1 d) 3, 1, 2, 4 e) 4, 3, 1, 2
Inorganic Matrix
35% consisting of minerals such as calcium salts {Hydroxyapatite Crystals} Potassium, Magnesium, Sodium as well
Sesamoid Bones
Specialized bones in TENDONS (Small, flat, oval) Used for leverage
Organic Matrix
65% {OSTEOID} Protein Fibers (Collagen) Proteogylcans, Glycosaminoglycans, Glycoproteins (GLUE)
Which of the following tissues could be found on or within a bone, such as the humerus?
Adipose, Nervous, Cartilage, Osseous
Osteoblasts
BONE BUILDERS / Immature cell found in Periosteum / MADE from osteogenic cells that perform BONE DEPOSITION
Stress and Compression equal what
Bone Deposition
Pressure in bones equal what
Bone Resorption
Testosterone promotes what
Bone deposition
Osseous Tissue
Bone tissue composed of extracellular matrix with small amount of cells
Fracture
Broken bone / Most severe
Which two minerals are stored in major quantities in bone tissue
Calcium and Phosphorous
Long bones add to their length at the epiphyseal plate. In this region which type of cells proliferate, become calcified, and are eventually replaced with mature bone cells, thereby adding to the bone's length?
Chondrocytes
Width growth results in what new layer
Circumferential Lamallae
What is secreted by osteoblasts during bone deposition?
Collagen Fibers
Periosteum
Composed of dense irregular connective tissue, forms a covering that is rich in blood cells and nerves
Yellow Bone marrow
Composed of triglycerides, blood vessels, and adipocytes Increases with age
Red Bone Marrow
Consists of loose connective tissue that supports islands of blood forming, hematopoietic cells Increases with age only found in pelvis, humerus, ribs, vertebrae, etc
Bone Remodeling
Continous formation of bone and loss
Hyaline Cartilage consists of
ECM and Chondrocytes
Epiphyses
ENDS of bones that are lined with Hyaline Cartilage
Bones that form below the head are what type of ossification and occurs within what model
Endochondral / Hyaline Cartilage
Which of the following hormones, in both adult males and females, ultimately ends growth of long bones at the epiphyseal plate? (This happens sooner in women than in men, and so men on average are taller than women)
Estrogen
Spongy Bone (cancellous)
Found inside cortical bone, honey-comb like structure provides a cavity for bone marrow
The process of intramembranous ossification generates bone within a pre-existing template composed of mesenchymal tissue. In contrast, endochondral ossification generates bone within a pre-existing template composed of _____.
Hyaline Cartilage
The first bone formed by both types of ossification
Immature bone (primary bone)
Irregular Bones
Include vertebrae and certain skull bones
Estrogen
Increases Longitudinal growth / inhibits osteoclasts
Testosteron
Increases appositional growth / rate of mitosis
Most of the bones of the skull are formed by this process.
Intramembranous Ossification
Once osteoblasts have surrounded themselves with the Extracellular Matrix of bone tissue, they remain inside a little chamber called the...?
Lacunae
Osteoclasts
Large multinucleated cells derived from fusion of cells formed in bone marrow; Responsible for process of bone resorption (Break down ECM) Secretes hydrogen ions to do so.
The term diploe refers to
Layer of spongy bone sandwiched between compact bone
Length Growth only occurs in
Long bones
Growth in length is called
Longitudinal
Secondary Bone is mature or immature
Mature
Osteocytes
Mature; osteoblasts eventually surround themselves in bone matrix in the small cavity lacuna; they become osteocytes that are no longer actively synthesizing bone matrix
Long Bone
Named for shape not size; longer than wide
Bone Deposition
New bone is formed via osteoblasts
When bones increase in thickness (diameter) as an individual grows to adulthood, which tissue or cells of the bone begin this growth process?
Osteoblasts in the Periosteum
Which is formed from the fusion of as many as 50 monocytes (a type of white blood cell)?
Osteoclast
Parathyroid Hormone stimulates
Osteoclastic activity
Bone Resorption
Osteoclasts secrete H+ ions onto ECM which make it more acidic
What is the correct sequence of development of bone cells?
Osteogenic cells --- Osteoblasts --- Osteocytes --- Osteoclasts
Bone tissue stores 99% of the body's calcium. Calcium plays important roles beyond the mineralization of bones. The exchange of calcium between bone and body fluids (especially the blood) is regulated by several hormones. Which of the following is the most important hormone regulating calcium exchange?
PTH Parathyroid Hormone
Functions of the skeletal system
Protection, Mineral storage, Blood Cell Formation, Fat Storage, Movement, Support
Short Bone
Roughly cubed shaped (ankle & wrist)
Which type of bone is stronger and why
Secondary Bone; it has a higher inorganic matrix
Lacunae
Small cavities filled with ECM located between lamallea
Calcitonin
Stimulates osteoblastic activity
Bones can only assist in providing movement when they are tugged on by the appropriate skeletal muscles
TRUE
In a newborn, all bone marrow is red, which means all of the infants marrow can make blood cells
TRUE
Flat Bone
Thin & Broad Bones (Pelvis, Ribs, Sternum)
Compact bone is composed of units called osteons. In Contrast, spongy bone is composed of..?
Trabeculae
Canaliculi is what
a transport system between lamallea that allows for oxygen and nutrients to be passed along
Which is NOT a part of the events that result in parathyroid hormone's control of blood calcium levels?
a) In response to low Ca2+ levels, cells of the parathyroid gland speed up synthesis of PTH (parathyroid hormone) b) PTH acts on the kidneys to decrease excretion of calcium in the urine c) PTH stimulates the conversion of vitamin D into its active form (calcitriol) *d) PTH acts on the parafollicular cells of the thyroid gland to increase the level of the hormone calcitonin e) PTH increases the number and activity of osteoclasts which dissolve bone matrix and release Ca2+ to diffuse into the blood stream
In terms of bone health, why would a physician advise an older patient to do more weight-bearing activity such as walking, jogging, or use of moderate weights?
a) it promotes normal bone remodeling b) osteoblasts deposit more minerals salts and collagen fibers as a response to mechanical stress c) being sedentary (not physically active) promotes bone loss through resorption by osteoclasts d) bone formation in stressed bones is stimulated by the tug of muscles (when exercising) e) all of these explain why a physician would give such advice to a patient
Which of the following best describes the process of bone resorption in bone remodeling?
acids and enzymes released by osteoclasts degrade collagen and dissolve away minerals, which diffuse through the interstitial fluid into nearby blood capillaries
perforating fibers
anchors periosteum to bone
Estrogen promotes what
decreases osteoclastic activity
compact bone
hard, dense outer region that allows for linear compression, and twisting forces
Bone Formation is called
ossification
Diaphysis
shaft of bone
Bones often become less dense with aging (osteopenia). Bones can also become more brittle (less flexible). This is due to which factor?
with aging, there is a reduction in collagen synthesis by osteoblasts, which means a loss of tensile strength