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Lecture 4
The Skeletal System Includes
58
Anatomy
09/28/2010

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Term
the skeletal system includes: (4)
Definition

  1. bones 
  2. cartilage
  3. ligaments
  4. other connective tissues that stabilize and connect bones

Term
functions of the skeletal system (5)
Definition

  1. provide and support framework for
  2. store minerals and lipids
  3. blood cell production
  4. protects
  5. leverage

Term
what minerals and lipids are stored in the bones?
Definition

  • calcium- 98% deposited in skeleton; important for normal concentrations of calcium, phosphorus, magnesium throughout the body
  • yellow marrow- lipid storage (energy source)

Term
the bone cells and ground substance give bone flexibility and strength; the inorganic salts give it hardness
Definition

  • 2/3 calcium phosphate (strong but not flexible)
  • 1/3 protein/collagen fibers (tough, flexible)
  • 2% only - osteocytes and other cells

Term
what are the 4 principle types of bone cells contained within bone tissue?
Definition

  1. osteogenic (osteoprogenitor) cells
  2. osteoblasts
  3. osteocytes
  4. osteoclasts
the classification is based on: 1. orientation fibers in bone matrix 2. woven vs. lamaller

Term
woven
Definition
remodeled
Term
lamaller
Definition
organized, layers, nice pattern
Term
osteoprogenitor
Definition

 

  • also called osteogenic cells
  • not many of these
  • osteoprogenitor cells are undifferentiated cells that divide to produce osteoblasts and when needed (ie. fracture repair trauma)

 

Term
osteoblasts
Definition

  • osteoblasts are immature cells responsible for the production of new bone through a process called osteogenesis
  • secretes an un-miniralized substance that later becomes mineralized, forming bone matrix
  • they are found in areas of high metabolism (ie. periosteum, endosteum)

Term
osteocytes/osteons
Definition

  • osteocytes are mature bone cells derived from osteoblasts that have secreted bone tissue around themselves; located in spaces (or lacunae) between layers (or lamelle) of the hard matrix of the bone
  • small channels connect the lucunae and are called canaliculi; these provide passage for nutrients, waste products , and hormones (diffusion in and out of microcirculation)
  • secretes enzymes and maintain healthy bone and mineral content by regulating calcium release and deposition

Term
osteobasts are immature cells responsible for the production of new bone through a process called __________
Definition
osteogenesis
Term
osteocytes are mature bone cells derived from _________
Definition
osteoblasts
Term
osteocytes secrete enzymes and maintain healthy bone and mineral content by regulating ____________
Definition
calcium release and deposition
Term
osteoclasts
Definition

  • osteoclasts are giant, multinuclear cells that secrete acids that dissolves bony tissue, releasing calcium, phosphate, magnesium and other minerals into the circulatory system to maintain homeostasis for these concentrations in body fluids; this process is called osteolysis
  • the breakdown of bone tissue is n enzymatic process, meaning it requires enzymes for osteolysis to take place
  • this process, osteolysis, is important for bone growth, healing and remodeling

Term
bone-lining cells
Definition

  • cells that are derived from osteoblasts along the surface of most bones in the adult skeleton
  • these cells help regulate the movement of calcium and phosphate into and out of bone matrix

Term
types of osseous tissue
Definition

  • most bones contain both types of bone tissue
  1. compact bone
  2. spongy bone

Term
compact bone
Definition

 

  • dense bone that forms solid outer wall of bone
  • also known as cortex or matrix 
  • contains functional units called osteons that usually run parallel to the long surface

 

Term
compact bone varies in thickness depending on 2 factors ...
Definition

 

  1. stresses on bone
  2. how many directions that stresses come from 

 

Term
osteons contain a central canal (vessels, nerves run here), _____, and _____ with osteocytes (lacunae are linked by _____)
Definition

  • concentric lamellae
  • lacunae
  • canaliculi

Term
compact bone contains interstitial lamellae; these fill spaces between osteons but ______
Definition
have no central canal
Term
structure of a typical long bone (11 things)
Definition

  1. shaft or diaphysis (spongy bone)
  2. medullary cavity
  3. endosteum
  4. yellow bone marrow (ends of long bones)
  5. epiphysis (flaring out)
  6. red bone marrow
  7. articular cartilage (at the ends, allows bones to touch each other)
  8. epiphyseal plate
  9. epiphyseal line
  10. periosteum
  11. perforating fibers

Term
what are the 2 types of connective tissue in the bone?
Definition

  1. endosteum- a thin layer of CT that lines the medullary cavity
  2. periosteum- a dense layer of CT that lines the surface of the bone (superficial to endosteum)

Term
periosteum
Definition

  • outer layer bone that serves as a site of attachment for ligaments and tendons, provides protection, and gives durable strength to the bone
  • this CT is part of deep fascia of body; it invests itself into the compact bone through Sharpey's (or perforating) fibers
  • has 2 layers (1) fibrous other and (2) cellular inner that includes osteoblasts and osteoclasts
  • it covers all surfaces of bone except the inside of the joint capsule; however, it is continuous with the joint capsule fibrous outer layer

Term
4 main funtions of the periosteum
Definition

  1. it separates the bond from the surrounding tissues, but it is continuous with the joint connective tissues and tendons/ligaments
  2. it allows a route for circulatory, lymphatic, and nervous supply (without periosteum bone dies)
  3. is an active part of bone growth and repair (through osteoblast/osteoclast activity)
  4. the periosteum, tendons and ligaments are made part of bond structure by thick bundles of collagen fibers called sharpey's fibers in periosteum cellular layer - very strong bond into matrix of bone

Term
endosteum
Definition

  • a thinner membrane of connective tissue that is internal to periosteum
  • contains osteoblasts and osteoclasts
  • lines the central canal of osteons
  • covers the trabeculae of spongy bones
  • active in bone growth and repair

Term
spongy bone
Definition

  • aka trabeculae
  • an open structure that is surrounded by compact bone
  • surrounds bone marrow or medullary cavity (red and yellow marrow found here)
  • no osteons instead trabeculae which are formed by branching lamellae (from matriz) to form a network-like structure

Term

lamallae are connected to ______ of compact bond for nurtrient and nervous supply

 

Definition
canaliculi
Term
spongy bone is much _____ than compact bone
Definition
lighter! and serves to (1) lessens weight of skeleton, and (2) heightens motion ability
Term
spongy bone is only found where _____ comes from many directions or where there is not a lot of stress on bones
Definition
stress
Term
spongy bone is found at either end of _____ bones where there is articulation with another bone (ie at the epiphyses); the weight is transferred through ______ into diaphysis (ie shaft or long axis)
Definition

  • long bones
  • trabeculae

Term
bone strength is...
Definition
extremely strong in one direction and very weak in another direction (eg. femur, where osteons are parallel to the shaft and a side impact can fracture easily)
Term
we need our skeletal system to have strong _____ support to resist _____ stress due to things like ...
Definition

lateral

 

medial

 

increased bone mass, muscle mass, fibrous mass

Term
bone growth & develpoment
Definition

  • determines the overall size of our bodies
  • occurs from approx. 6 weeks embryologically to approx. 25yrs old
  • as bones grow, hyaline cartilage or embryonic mesenchyme replaced by bone -this is called ossification and it occurs though calcification (ie. the deposit of calcium salts in tissues)

Term
2 types of ossification 
Definition

(1) intramembranous (or dermal) ossification 

 

(2) endochondral ossification

Term
intramembranous ossification
Definition

  • occurs in the fetal period (2months-2yrs)
  • the bone develops when osteoblasts differentiate within fibrous CT
  • usually occurs in the deeper layers of skin or dermis and develops flat bone (ie. skull, mandible, clavicle)
  • generally the structure formed is a spongy bone composition but with thin layers of compact bone surrounding

Term
endochondral ossification
Definition

  • begins with the formation of hyaline cartilage as a structural model during the fetal period (2-25yr)
  • it proceeds to replace the cartilage model with bone
  • bone development proceeds initially from a primary center of ossification, which is usually located in the diaphysis of the cartilage system
  • bone develops around the circumference also 

Term
the  diameter of the bone is increased through _____________
Definition
appositional growth
Term
appositional growth
Definition

the process of adding layers of bone tissue and supporting vessels and innervation to existing bone structures superficially

 

Term
where does appositional growth occur?
Definition
it occurs on the outer surface of the bone where periosteal osteoblast cells differentiate, creating ridges that eventually surround parallel blood vessels
Term
the bony matrix develops and becomes the typical ______
Definition
osteon
Term
osteoclasts may be removing bone matrix at the core for the development of a ________ cavity
Definition
marrow
Term
(1) during osteogenesis, _______ move from the center (_______) of ossification toward the epiphyses (_____)
Definition

osteoblasts

 

diaphysis

 

ends

Term
(2) epiphyseal plate
Definition
the junction where the hyaline cartilage is replaced by bone at the junction between the diaphysis and the epiphyses, it is just beyond the metaphysis (of flared part of the diaphysis, nearest to the epiphyses)
Term
study the process of increasing the length of a developing bone!
Definition
Term
Definition
Term
5 zones
Definition

  1. zone of reserve cartilage
  2. zone of cell poliferation
  3. zone of cell hypertrophy
  4. zone of calcification
  5. zones of bone depostion

Term
the required diet for bone growth
Definition

  • dietary calcium and phosphates
  • dietary vitamin A and C
  • dietary vitamin D

Term
hormonal production to regulate the pattern of growth including
Definition

  • growth hormone (released from the pituitary) and thyroxine (released from the thyroid gland)
  • sex hormones (testosterone, estrogen) - released from reproductive organs, adrenal cortex; responsible for differences in bone growth between sexes

Term
long bones have 3 characteristics..
Definition

  • diaphysis
  • epiphysis
  • marrow cavity/medullary cavity
  • examples include the femur, ulna; found in the appendicular skeleton

Term
short bones
Definition

  • boxier, no visible long axis
  • contains a cortex and spongy bone
  • examples include carpals (found in the hands) and tarsals (found in the feet)

Term
flat bones
Definition

  • flat, thinner, strong and light
  • parallel layers of compact bone sandwiching spongy bone
  • large area for attachment of muscle, and protects underlying soft tissue
  • examples include the skull, sternum, ribs and scapula

Term
irregular bones
Definition

varied structure with surfaces that are short and can be notched ridged or flat

examples include vertebrae, ethmoid bones (located in the skull), and lacrimal bones

Term
sesamoid bones
Definition

  • small, round and flat
  • develops within tendons (patella of knee or knee cap) or sometimes near the joints of the hands and feet

Term
sutural or wormian bones
Definition

  • small, flat; varied shape
  • found between flat bones of skull, invading the suture line
  • variation among people as to the number, size and shape

Term
the adult skeleton consists of approx ____ bones. exact number differs depending on _____
Definition

206

 

age, genetic factors, and bone disorders

Term
the human skeleton can be divided into 2 portions
Definition

  1. the axial skeleton
  2. appendicular skeleton

Term
the axial skeleton (40%) consists of: 6 things
Definition

  1. skull - consists of cranial bones (forms the cranium) and facial bones
  2. 3 auditory ossicles - the "ear bones"
  3. hyoid bone- located above the larynx and below the jaw or mandible. it supports the tongue and assists in swallowing
  4. vertebral column - 26 vertebrae disks (the sacrum can also be considered part of the pelvic girdle
  5. rib cage
  6. sternum (can be considered part of the pectoral girdle)

Term
the appendicular skeleton (60%) consists of 4 things...
Definition

  1. pectoral girdle - consists of the scapulae (shoulder blades) and the clavicle (collarbones) provides attachment for the muscles that move the arm
  2. upper extremities
  3. pelvic girdle- the gipbones; supports the weight of the body and protects the organs within the pelvic cavity
  4. lower extremeties