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127 Cards in this Set
- Front
- Back
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What is Osteogenesis?
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The formation of new bone.
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What is Ossification?
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The process of replacing other tissues with bone
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What are the two types of ossification?
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1. Intramembranous
2. Endochondral |
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What is Intramembranous Ossification?
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When bone develops within sheets/membranes of connective tissue.
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What is Endochondral Ossification?
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When bone replaces existing cartilage.
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What does skeletal growth determine?
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Size and proportion of body
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When does skeletal growth begin?
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6 weeks after fertilization
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When does skeletal growth stop?
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Usually stops between ages 16-25
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When does intramembranous ossification begin?
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Begins when osteoblasts differentiate within fibrous connective tissue.
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What does Intramembranous Ossification resemble at first?
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It resembles spongy bone at first. Then, calcifies into compact bone.
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What is an ossification center?
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The place where ossification first appears.
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In intramembranous ossification, what type of bone growth is there?
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Bone growth is active; blood vessels in connective tissue become trapped during embryonicdevelopment and become trapped in bone.
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Where does intramembranous ossification occur?
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In several flat bones of the skull, lower jaw and clavicles.
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How do most skeletal bones form?
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Most form by Endochondral ossification.
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In endochondral ossification, where is the primary ossification center?
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Bone formation begins in the middle at the primary center of ossification.
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In Endochondral Ossification, where is the secondary ossification center?
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In the epipyses.
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What is also referred to as a growth plate?
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Epiphyseal plate.
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In endochondral ossification, when does bone growth accelerate?
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At puberty
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What is Appositional Growth?
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When cells of the periosteum develop into osteoblast forming new matrix; increases the diameter of the bone shaft.
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What are requirements for bone growth?
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Calcium, phosphate, vitamin a and c, vitamin d, and hormones
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What is calcium used for in bone growth?
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Osteogenesis
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What is phosphate used for in bone growth?
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Osteogenesis
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What are vitamin A and C used for in bone growth?
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Bone growth and development
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What is vitamin D used for in bone growth?
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Normal cacium metabolism
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What are hormones used for in bone growth?
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Normal skeletal growth and development.
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What is bone remodeling?
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The process of removing and replacing the protein and mineral components of bone.
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In remodeling, what are formed by osteoblasts and removed by osteoclasts?
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Osteons
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What is the adult turnover rate for remodeling bone?
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18% of protein and mineral components are replaced each year.
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What is deposition?
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To deposit bone tissue
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What is an important mineral reservoir?
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bone
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What are essential to maintaining bone strength and bone mass?
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Stresses applied to bones during exercise.
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What do heavily stressed bones become?
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Thicker and stronger and develop more prominent ridges.
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What occurs in the skeleton after brief periods of inactivity?
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Degenerative changes occur.
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What 3 hormones regulate Calcium Phosphate Homeostasis?
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The parathyroid hormone, calcitriol and calcitonin.
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What does the parathyroid hormone do?
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It increases calcium ion levels in the body, not for bone deposition.
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What hormone is referred to as an "emergency hormone"?
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Parathyroid hormone.
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What hormone does the parathroid hormone work with?
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Calcitrol
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What does the parathyroid hormone do to osteoblast activity?
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Decreases activity
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What does the parathyroid hormone do to osteoclast activity?
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Increases activity
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What does calcitriol do?
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Increases calcium ion levels in body fluid for bone deposition.
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What hormone does calcitriol work with?
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Parathyroid hormone
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What does calcitriol do to osteoclast activity?
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Decreases activity
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What does calcitonin do?
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Lowers calcium ion levels in the blood.
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What is calcitonin secreted by?
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The thyroid gland.
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What does calcitonin do to osteoblast activity?
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Increases/stimulates activity
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What does calcitonin do to osteoclast activity?
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Decreases/inhibits activity.
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How are fractures classified?
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By external appearance, location and the nature of the crack or break.
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What is a fracture?
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A crack or a break in a bone
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What are 4 types of fractures?
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Simple, Compound, Spiral and Compression fractures
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What are simple/open fractures?
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Fracture is completely internal; skin does not break
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What are compound/open fractures?
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Fracture projects through the skin; more dangerous; infection and bleeding possible
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What are spiral fractures?
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Fracture is twisted when broken
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What are compression fractures?
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The bone is crushed on impact.
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How many bones are in the human body?
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206
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What is the skeletal system made of?
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Bones of the skeleton, cartilages, joints, ligaments, and other connective tissues that connect or stabilize them.
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What are the functions of the skeletal system?
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Support, Storage, Blood Cell Production, Protection, Leverage, Muscle Attachment, and Detoxification.
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What are bones major storage areas of?
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Calcium Phosphate and Lipids-in yellow bone marrow.
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What is the structure of bones made of?
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Bone or osseous tissue, supporting connective tissue; fibers and ground substances make matrix
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What in bone matrix gives it a hard stony appearance?
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Calcium salts
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What makes up 2/3's of the weight of a bone and adds strength to it?
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Calcium Phosphate
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What makes up 1/3 of a bone and adds flexibility to it?
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Collagen Fibers
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What are the 4 general bone shapes?
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Long, short, flat and irregular
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What are characteristics of long bones?
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They are longer than they are wide. They have a diaphysis, epiphysis, marrow cavity, hyaline cartilage, periosteum and endosteum
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What is a Periosteum?`
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The layer that surrounds a bone.
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What does the periosteum provide for a bone?
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A route for circulatory and nervous supply.
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What activities does the periosteum participate in?
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Bone growth and repair
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What is the Endosteum?
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The cell layer within the bone that lines the marrow cavity and other inner surfaces.
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When is the endosteum active?
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Active during bone growth, repair and remodeling.
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What are features of short bones?
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Dimensions are pretty much equal. THey are smaller bones.
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What are features of flat bones?
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They are thin and wide
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What are features of irregular bones?
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They do not have definite shapes They have complex, unclassifiable shapes.
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What are two types of bone (osseous) tissue?
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Compact and spongy bone tissues.
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What is an osteon?
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The basic functional unit of compact bones
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What are the parts of an osteon in compact bone tissue?
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Osteocyte, lacunae, lamellae, canaliculi, central canal, and perforating canal.
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What are lacunae?
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The pockets that house osteocytes; located inside lamellae.
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What are lamellae?
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The concentric layers of bone within an osteon; layers of calcified matrix and collagen; have a bulls eye look.
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What are canalculi?
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A branching network of small canals radiating through lamellae interconnecting the lacunae with one another and with the Haversian Canal.
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What is a central canal?
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Also known as a haversian canal. They contain blood and lymphatic vessels that nourish the osteocytes.
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What is a perforating canal?
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Also called Volkmann's Canal. It connects blood vessels of the periosteum to Haversian Canal, delivers oxygen deeper to supply the marrow cavity.
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What are features of compact bone?
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They are dense and solid
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Where does compact bone form?
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Outside the wall of the bone
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Does compact bone contain blood vessels?
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Yes
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What is the function of compact bone?
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To provide strength
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Where is compact bone located?
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It covers bone surfaces except where there is articular/hyaline cartilage.
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What does spongy bone look like?
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It looks like an open network, it contains air spaces.
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Where does spongy bone form?
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On the inside of bone, surrounds marrow cavity
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Does spongy bone have osteons?
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No
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Does spongy bone have trabeculae?
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Yes
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Does spongy bone have blood vessels?
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No
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How muct the nutrients coming to spongy bone get in?
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Diffuse from outermost canaculi through the trabeculae.
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How must the nutrients coming to compact bone get in?
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Through the canal system of the osteon
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Is compact or spongy bone lighter?
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Spngy bone is lighter and less dense
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What does spongy bone consist of?
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trabeculae, and bars of bone adjacent to small, irregular cavities that contain red bone marrow.
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How do canaliculi recieve their blood supply?
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By connecting to adjacent cavities instead of the central canal.
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How are trabeculae organized?
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in a manner that provides the maximum strength
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What way do the trabeculae of spongy bone follow stress lines?
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They follow the lines of stress and can realign if the direction of stress changes.
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What is an osteocyte?
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A mature bone cell that cannot divide.
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What are osteocytes responsible for?
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The maintenance and turnover of mineral content of bone.
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What is the most abundant bone cell?
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Osteocyte.
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What are the functions of osteoclasts?
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To dissolve bone (osteolysis), help regulate phosphate and calcium concentrations and to dissolve fibers and matrix of bone.
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What are the functions of Osteblasts?
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To form bone (osteogenesis), and produce fibers and martix of bone.
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What immature bone cell matures into an osteocyte?
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Osteoblast
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What is found in the spaces of spongy bone?
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Myeloid tissue
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What is myeloid tisse?
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Blood producing tissue
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What does red marrow produce?
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Both red and white blood cells.
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Does red marrow increase in proportion to bone growth?
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No
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What does much red marrow in adults change into?
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Yellow (fatty) marrow
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What does yellow marrow mostly consist of?
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Fat cells.
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Under extreme hematopoietic stress, what can yellow marrow revert to?
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Red marrow
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What do compact bones cover?
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Bone surfaces except in joint capsules.
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What are joint capsules covered with?
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Articular/hyaline cartilage
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What kind of stresses apply to the location of most compact bone?
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Stresses that come from limited ranges of directions.
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When can bones bend?
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In disorders that reduce the calcium salts found in the skeleton. This causes there to be more collagen. Ex: Rickets.
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What kind of stresses apply to the locations of most spongy bone?
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Spongy bone is only found in areas that are not stressed or where stresses come from many directions.
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How does spongy bone contribute to the skeleton?
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It makes the skeleton lighter and easier for muscles to move.
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Is movement a function of the skeletal system?
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No, leverage is a function of the skeletal system that allows the muscle system to move.
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What is matrix?
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The non-living portion of a bone.
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What are structural changes of osteoporosis?
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reduced bone mass, thin, brittle, less calcium, and less trabeculae.
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What can prevent osteoporosis?
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Exercise, therapy injecting hormones, and increasing calcium intake through vitamins and food.
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Why are females more prone to osteoporosis?
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They go through menopause which slows the production of estrogens. Sex hormones are important in maintaining normal bone deposition rates.
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Why do less men have osteoporosis than women?
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Men continue producing androgens throughout their life.
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What are the percents of males and females over 45 with psteoporosis?
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males- 18%
females- 29% |
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What is ossification?
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The process of replacing other tissues with bone. Happens in skeletal and muscle tissue.
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Where is the primary ossification center?
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In the middle of the diaphysis
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Where is the secondary ossification center?
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In the middle of the epiphysis
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What kind of cartilage does bone develop from?
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Hyaline cartilage
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What causes variations in body size and proportions between men and women?
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differences in the amounts of sex hormones.
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