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