Bones Ch 6
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The skeletal system is composed of what 3 things to form the internal framework?
bones, cartilage, and joints
What are the functions of bones?
provides shape to the body, attachment sites for muscle, and storage depot for essential minerals
What is cartilage?
connective tissue that aids in support & movement as it cushions bone surfaces & supports body structures and lays down initial skeletal structure.
What is the location and structure of cartilage?
Location? found throughout the body with 8 major body locations. Exernal ear, nasal, articulate cartilage (ends of bones), costal cartilage, larynx cartilage, tracheal cartilage, vertebral discs, and pubic symphysis.
Structure? contains a great amount of water (60-80% water) & low blood vessels and can reshape easily.
What are the 3 types of cartilage?
Hyaline Cartilage, Elastic Cartilage, and Fibrocartilage
What is Hyaline Cartiage?
Location? between joints like the elbows, knees, on the ribs around the sternum, hip joint, nuckles on toes & feet, articulate cartilage, between metacarpels & metatarsals, nose, larynx & trachea, shoulder capsule. Anywhere where joints are bendable there is cartilage.
Structure? looks like glass, has chondrocytes and collagen, resists compresson well because the ground substance can hold large amounts of water, makes up the articular cartilage that covers the ends of adjoining bones in movable joints
Function? lines joints, provides support through flexibility and resilence
What is Elastic Cartilage?
Location? in the outer ear and epiglottis
Structure? has chondrocytes, collagen, & elastic fibers; highly elastic & tolerates repeated bending
What is Fibrocartilage?
Location? intermediate between hyaline & dense regular connective tissue. Found in areas that bear weight; between vertebrates, knees & pubic symphisis
Structure? thick collagen fiber rows alternate with chondrocyte rows, embedded in matrix; withstands high compression & tensionFunction? resists both strong compression & strong tension (pulling) forces
Put the 9 major body locations of cartilage in the cartilage category it belongs
1. external ear
3. articulate cartilage
4. costal cartilage
5. larynx cartilage
6. tracheal cartilage
7. vertebral discs
9. pubic symphysis
- 1. external ear - elastic
- 2. nasal - hyaline
- 3. articulate cartilage - hyaline
- 4. costal cartilage - hyaline
- 5. larynx cartilage - hyaline
- 6. tracheal cartilage - hyaline
- 7. vertebral discs - fibrocartilage
- 8. epiglottis - elastic
- 9. pubic symphysis - fibrocartilage
What does perichondrium mean?
around the cartilage & acts like a girdle to resist outward expansion when the cartilage is subjected to pressure; also functions in cartilage growth and repear
What does appositional growth mean?
growth from outside (outside in)
What does interstitial growth mean?
growth from within (inside out)
What happens to cartilage as you grow and stop growing?
Appositional growth stems from perichondrium towards center while interstitial growth stems from center toward perichondrium. Cartilage stops growing in late teens when the skeleton itself stops growing & there is no more chondrocytes dividing.
What is Calcified Cartilage?
occurs when calcium deposits form within the cartilage and can cause pain or reduce the range of motion of a joint
What are bones?
vascular (has blood vessels) and has bone cells embedded in a matrix that has a high concentration of collagen & minerals, but only has little water.
What are the functions of bones?
- 1. Support - give body shape, hold up the body, bare its weight, & contain organs
- 2. Movement - bone, joints, & skeletal muscle work together with bones to make movements possible
- 3. Protection - surround soft tissue organs to provide support
- 4. Storage - hard matrix that make up bones store minerals like calcium & phosphate
- 5. Blood Formation - contains red (makes blood cells) & yellow bone marrow (site of fat storage)
What are the four classes of bones?
- 1. Long Bone - longer than there are wide, has a shaft plus two disinct ends (most bones in the limbs are long bones and fingers & toes are long bones)
- 2. Short Bone - cubed-shaped (occur in wrist & ankle..also...patella is a short bone)
- 3. Flat Bones - thin, flattened, usually somewhat curved (most cranial bones of skull are flat, as are the ribs, sternum, & scapula (shoulder blade)
- 4. Irregular Bones - varios shapes that do not fit in the above category (examples: vertebrae & hip bones)
What is the structure of compact bone?
external layer appearing as a dense solid mass as seen on the shaft and edges of long bones and holds yellow bone marrow
What is the structure of spongy bone?
internal layer that has a trabeculae structure surrounded by a layer of compact bone found on the end of long bones and holds red bone marrow
What is the structure of a typical long bone?
All the long bones in the body have the same general structure and has both compact & spongy bone.
What is Diaphysis and Epiphyses?
Diaphaysis forms the long axis of a long bone and the Epiphyses are the bone ends
The joint surface of each epiphysis is covered with what?e
a thin layer of hyaline cartilage called articular cartilage
What is articular cartilage?
a thin layer of hyaline cartilage to facilitate joint movement lined with the ends of long bones.
Between the diaphysis and each epiphysis of adult long bone is what?
an epiphyseal line
What is the difference between an epiphyseal line and an epiphyseal plate?
Epiphyseal line is fully grown (adult) and Epiphyseal plate is growth (grows during childhood to lengthen the bone)
What are the main vessels serving the diaphysis?
nutrient artery and nutrient vein = run through a hole in the wall of diaphysis called nutrient foramen (opening)
What is the structure of the nutrient artery?
runs inward to supply bone marrow & spongy bone. Branches than extend outward to supply the compact bone.
What is the structure and location of the Medullary Cavity?
Location? the very center of the diaphysis of long bones
Structure? contains no bone tissue and is filled with yellow bone marrow
What is the Periosteum structure, location, and function?
Structure? richly supplied with nerves & blood vessels; secured to the underlying bone by sharpey's fibers (thick bundles of collagen that run from the periosteum into the bone matrix); Has two sublayers: a superficial layer of dense irregular connective tissue (resists tension placed on a bone during bending) and a deep layer called osteogenic containing osteoblasts & osteoclasts.
Location? around the bone and covers the entire outer surface (compact bone) of each bone except on the ends of epiphyses
Function? provides insertion points for the tendons and ligaments that attach to a bone
What is Endosteum?
Location? within the bone and covers the trabeculae of spongy bone & lines the central canals of osteons.
Structure? It is also osteogenic containing both osteoblasts & osteoclasts
What is the difference between Periosteum and Endosteum?
Periosteum means around the bone covering compact bone externally and Endosteum means within the bone covering spongy bone internally
What is yellow bone marrow and red bone marrow?
yellow bone marrow stores fat held by compact bone and red bone marrow has blood cells held by spongy bone
What is the structure of a flat bone?
consist of a layer of spongy bone with trabeculae sandwiched between two thin layers of compact bone
What is osteoclast, osteoblast, and osteocyte?
Osteoclast are bone destroying cells (bone breakers) that help to release minerals into blood stream
Osteoblast are bone generation cells (bone makers) that lay down more matrix
Osterocyte is a mature bone cell that maintains bone matrix
What is Osteon?
Haversian System that is a group of concentric tubes that in cross-section appear as rings and are made up of lamella (layer of bone matrix with collangen running in one direction). Within the lamella is a network of osteocytes embedded in a lacunae & connected by little canals called canaliculi
What is lamella?
"little plate" - layer of bone matrix with collagen running in one direction with two kinds of lamella (Circular lamella called concentric and paralellel lamella called interstitial lamella)
Within the lamella is a network of what?
osteocytes embedded in lacunae & connected by canaliculi (little canals)
The trabeculae of spongy bone is made up of what?
lamella and osteocytes, but not osteons because trabeculae are so small
What is central canal, perforating canals, and canaliculi?
central canal - middle of osteon
perforating canals - connect osteons (another name - volkmans canal)
calnaliculi - small connections between lacunae that link adjacent osteocytes
What are the organic and inorganic components of bone?
organic (35%) are cells, fibers, and ground substance
inorganic (65%) are minerals, mostly calcium and phosphate
Osteogenesis and ossification are both names for the process of what?
bone-tissue formation (bone framework is first laid down as cartilage and then changes to bone)
What is Intramembranous ossification?
process in which bone is not laid out. First starts in cartilage. Happens in membrane bone that form the skull and clavicle
What week does Intramembranous ossification start and what happens during this week?
week 8 of development cells cluster within mesenchyme membranes and become osteoblast secreting osteoid (bone matrix) forming woven bone tissue that thickens into trabeculae. The outer trabeculae thicken to form compact bone.
What is Endochondral Ossification?
process begins late into second month of development and is completed in adulthood (all bones of the skull down except clavicle are endochondrial bones)
What happens during stage 1, 2, 3, 4, and 5 of endochondrial ossification?
1 - Bone cartilage forms around hyaline cartilage model (by week 8 the cartilage model has perichondrium that becomes bone forming periosteum & a bone collar forms around diaphysis)
2 - Cartilage in the center of diaphysis calcifies and then develops cavities (chondrocytes signal calcification at the center of diaphysis. Calcification of the cartilage deprives the cells of nutrients and once they die, cartilage disintegrates leaving a cavity at the center that influences elongation & provides a space for the primary ossification center)
3 - periosteal bud invades the internal cavities and spongy bone begins to form (primary ossification center forms at diaphysis by third month of development. Periosteal bud includes nutrient blood vessels, bone cells, and bone marrow forming cells)
4 - diaphysis elongates and a medullary cavity forms as ossification continues. Secondary ossification centers appear in the epiphyses in preparation for stage 6. before birth or shortly after, epiphyses forms secondary ossification centers and ends of the bones ossify.
5. epiphyses ossifly and when completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilages
How often does bone remodeling occur for compact bone and spongy bone?
Compact bone is entirely replaced every 10 years and spongy bone every 3-4 years
What is the difference between a simple fracture and a compound fracture?
A simple fracture is when a bone does not pierce the skin (breaks cleanly) and a compound fracture is when the bone does pierce the skin (through skin)
What is a Comminuted Fracture?
3 + fragments - bone fragments into three or more pieces (common in the older age)
What is a Spiral fracture?
due to twisting force - Ragged break occurs when excessive twisting forces are applied to bone (common sports fracture)
What is a depressed fracture?
inward depression - Broken bone portion is pressed inward (typical of skull fracture)
What is a compression fracture?
crushed - bone is crushed (common in porous bones subjected to extreme trauma, as in a fall)
What is an epiphyseal fracture?
plate tears - Epiphysis seperates from diaphysis along with epiphyseal plate (tends to occur where cartilage cells are dying & calcification of matrix is occuring)
What is a greenstick fracture?
partial break - bone breaks incompletly with only one side of the shaft breaking and the other side bending (common in children)
Explain the four ossification steps in a fracture
1. Hemotoma formation - broken blood vessels release blood that form a clot
2. Fibrocartilaginous callus formation - periosteum & endosteum form many bone-forming cells that invade the clot creating a callus containing fibrocartilage & hyaline cartilage
3. Body callus formation - trabeculae form in callus by enchondrial ossification becoming the bony callus (takes about 2 months)
4. Bone remodeling - the callus is removed by osteoclast removing excess bone mass & compact bone is laid out
What is Osteoporosis?
low bone mass due to deterioration and fractures occur easily. Bone reabsorption is faster than bone deposition
What is Osteomalacia?
soft tissue weakening of the bone resulting from lack of Vitamin D or calcium phosphate and occurs in adults
What are Rickets?
soft tissue weakening of the bone resulting from lack of Vitamin D or calcium phosphate and occurs in children (more severe because bones still growing)
What is Paget's Disease?
disorder in newly formed bone where bones become soft & weak because new bone is laid out faster than it matures & less mineralization.(happens before age 40 and may result from a viral infection). Bones thicken irregularly.
What is Osteosarcoma?
bone cancer that affects people 10-25 years old originating in long limb bones with the tumor developing in regions near growth plates.
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