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Week 4
Lecture 3
78
Anatomy
Undergraduate 2
09/25/2014

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Term
What are the functions of the skeletal system?
Definition
support, protection, movement, mineral storage, and blood cell formation
Term
How does the skeletal system aid in support?
Definition
provides support for the entire body
Term
How does the skeletal system aid in protection?
Definition
protection of vital organs: brain
Term
How does the skeletal system aid in movement?
Definition
skeletal muscles pull on bones to create movement
Term
How does the skeletal system aid in mineral storage?
Definition
calcium and phosphate are stored until the body needs it
Term
How does the skeletal system aid in blood cell formation?
Definition
blood cells are formed in bone marrow
Term
What are the two types of tissue found in bone?
Definition
compact and spongy
Term
What is compact bone?
Definition
outer portion of bone; smooth, continuous, dense, solid bone
Term
What is spongy bone?
Definition
inner portion of bone; same material as compact bone, but it's arranged in narrow, irregular bars; not as smooth as compact bone
Term
What are the four types of bones in the body?
Definition
long, short, flat, & irregular
Term
What are the two main parts of a long bone?
Definition
the diaphysis and epiphysis
Term
What is the diaphysis?
Definition
shaft in the middle of the bone, made up of compact bone and a medulary cavity
Term
What is the epiphysis?
Definition
bulbous ends of bones, made up of compact bone surrounding spongy bone
Term
What is the epiphysis made of?
Definition
articular cartilage and an epiphyseal line
Term
What is the purpose of articular cartilage on the epiphysis?
Definition
provides a smooth surface
Term
What is the purpose of the epiphyseal line in the epiphysis?
Definition
marks the spot of an old growth plate
Term
Where are membranes located on the bone?
Definition
inside and outside the bone
Term
What is the periosteum?
Definition
outside membrane of the bone that contains osteogenic cells
Term
What is the endosteum?
Definition
the inside membrane of the medulary cavity and the spicula of spongy bone that contains osteogenic cells
Term
What is the structure of short, irregular, and flat bones?
Definition
thin layer of spongy bone, called diploe, sandwiched between two plates of compact bone
Term
What is red marrow?
Definition
areas where red blood formation occurs
Term
Where is red marrow found in adults?
Definition
within trabecular cavities of select long bones and diploe of flat bones
Term
Where is red marrow found in infants?
Definition
in the medullary cavity
Term
What happens to red marrow after childhood?
Definition
area turns to fat and is referred to as yellow marrow
Term
What is the main component of compact bone?
Definition
osteon
Term
What is an osteon?
Definition
cylindrical structure that makes up the fundamental part of compact bone
Term
What is the lamellae?
Definition
thin, concentric layers that form the osteon
Term
What is the haversian canal?
Definition
central canal of osteon filled with blood vessels that allows the bone to be fed and nourished
Term
What is the volkmann canal?
Definition
transverse canal that connects blood vessels in order to bring blood from external to internal bone
Term
What is an osteocyte?
Definition
the mature bone cell
Term
What are lacunae?
Definition
small cavities that contain the osteocytes
Term
What are canaliculi?
Definition
small canals that connect lacunae and haversian canals
Term
What does canaliculi allow?
Definition
exchange of material between cells and between cells and blood supply
Term
What is interstitional lamellae?
Definition
layers of bone that lie between osteons in order to fill in the space and maintain the integrity of the bone
Term
What is the circumferential lamellae?
Definition
lie outside the osteon clusters and deep to the periosteum and encircle the entire bone
Term
What are perforated (Sharpey's) fibers?
Definition
extend from the fibrous layer of the periosteum into the bony matrix in order to secure and attach the periosteum to the underlying bone
Term
Where are perforated (Sharpey's) fibers especially found?
Definition
where muscles or ligaments/tendons attach
Term
What is the difference between the structure of spongy and compact bone?
Definition
less rigidly organized; don't contain osteons
Term
What is the structure of spongy bone like?
Definition
trabeculae form sort of a lattice work that gives the appearance of a sponge
Term
What happens when a bone is under more stress?
Definition
trabeculae align along lines of stress, so areas of continued stress develop thicker and more dense spongy bone
Term
What are the types of cells found in bone?
Definition
osteogenic, osteoblast, osteocyte, and osteoclast
Term
What are osteogenic cells?
Definition
stem cells which are mitotic, found in the periosteum or endosteum, that may differentiate into osteoblasts
Term
What are osteoblasts?
Definition
bone forming cells that secrete the bone matrix around where they are located
Term
What is included in the bone matrix?
Definition
collagen and calcium
Term
What are osteocytes?
Definition
mature bone cells that were originally osteoblasts; once the osteoblast has secreted enough matrix, it becomes an osteocyte
Term
What is the role of osteocytes?
Definition
responsible for maintaining the bone matrix; act as stress or stress sensors and respond to mechanical stimuli, such as bone loading or deformation
Term
What are osteoclasts?
Definition
bone "destroying"cells; phagocytes within the bone that destroy the matric
Term
What is the purpose of osteoclasts?
Definition
remodeling or growth, and allow calcium or phosphate to be released into the blood stream
Term
What is different about the osteocytes from the other bone cells?
Definition
it was derived from a different sort of stem cell
Term
What is the ground substance of the bone matrix made of?
Definition
called "osteoid"; proteoglycans, glycoproteins, and hydroxyapatites
Term
What are proteoglycans?
Definition
large proteins and carbohydrate groups found in the osteoid
Term
What are glycoproteins?
Definition
small proteins and carbohydrate groups found in the osteoid
Term
What are the fibers commonly found in the osteoid?
Definition
mostly collagen
Term
Describe collagen.
Definition
a helical protein
Term
How does bone tissue vary from cartilage?
Definition
bone is very dense due to low water content
Term
How does having compact bone peripherally and spongy bone centrally effect function?
Definition
it gives bones strength but leaves them lightweight
Term
How does having calcium phosphates as part of the osteoid effect function?
Definition
bones are important stores calcium and phosphate for cellular functions when they are released
Term
How do osteoclasts, osteoblasts, and osteogenic cells effect function?
Definition
they are important for bone development; osteoclasts break down bone for release of minerals and osteoblasts build up the bone
Term
How does having a marrow cavity effect function?
Definition
it gives a space for bone development (more active in childhood)
Term
What is osteogenesis?
Definition
the development of bone that occurs in the fetus
Term
What are the two types of osteogenesis?
Definition
intramembranous (within a membrane)
endochondral (inside cartilage)
Term
Describe the process of intramembranous ossification.
Definition
mesenchyme is the embryonic membrane in which flat bones are typically formed
Term
Describe endochondral ossification.
Definition
ossification that begins with a cartilage template and typically forms long bones
Term
Describe the process of endochondral ossification.
Definition
1) cartilage forms precursor tissue and osteoblasts form bone collar
2) central cartilage calcifies and cavities develop
3) periosteal bud invades and brings osteoclasts with
4) diaphysis elongates, medullary cavity forms, and secondary ossification begins at epiphyseal plate
5) epiphyses ossify leaving cartilate within epiphyseal plate
Term
Do long bones continue to grow?
Definition
yes, after the bone has been laid down within the original hyalin cartilage, long bones will continue to grow until you reach puberty
Term
How does long bone grow in length?
Definition
-cartilage grows at distal ends and epiphyseal plate
-cartilage is replaced by bone from osteroblasts
-osteoclasts follow behind and carve out the medullary cavity
Term
What is appositional growth?
Definition
the growth of a bone width wise
Term
How does appositional growth work?
Definition
periostial osteoblasts lay down bone and secrete matrix outwards
Term
What are the two ways bone function is regulated?
Definition
growth and remodeling
Term
How does growth hormone regulate growth of bones?
Definition
growth hormone secreted by the anterior pituitary gland causes the liver to release a substance called sonatomedins in order to promote cartilage growth at the epiphyseal plate
Term
How does thyroid hormone regulate growth of bones?
Definition
it also works like the growth hormone secreted from the anterior pituitary gland
Term
How do androgenic and estrogenic steroids regulate growth of bones?
Definition
they promote epiphyseal plate closure at puberty
Term
What is remodeling?
Definition
lifelong process where mature bone tissue is removed from the skeleton and new bone tissue is formed
Term
How does remodeling happen?
Definition
resorption, during which osteoclasts digest old bone, and formation, when osteoblasts lay down new bone until the resorbed bone is completely replaced
Term
How does the parathyroid hormone regulate bone remodeling?
Definition
it increases osteoclast activity when the blood calcium levels are low
Term
How does calcitonin regulate bone remodeling?
Definition
it inhibits osteoclasts
Term
What does Wolff's Law state?
Definition
bones grow and remodel in response to mechanical demand
Term
What are the statements of Wolf's Law?
Definition
1) assymetrical limb thickness will occur depending on which limb is dominant
2) there will be increased thickness at curved areas in order to prevent buckling
3) spongy bone forms trusses along lines of compression
4) there are enhanced bony projections at sites of muscle attachment
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