Chapter 6: Bones Flashcards
What are the 5 functions of bones?
support, storage, blood cell production, protection and leverage
how do bones support
framework for attachment of all kinds of softer tissus
what do bones store
minerals and lipids
What do bones produce and where?
blood cell production of all red blood cells and WBCs originate from stem cells in red bone marrow
define hematopoiesis
production of blood cells
How do bones protect
skull bones protect the brain
vertebrae protects spinal cord
ribs protect the heart and lungs
pelvis protects repro and digestive organs
What is leverage of bones?
bones acts as lever to go along with muscle contractions to allow movement
Give examples of long bone
arms, legs, hands, feet fingers and toes
What are flat bones
bones of teh sull cap, sternum, scapulae (shoulder blade)
purpose of flat bones
protection; extensive area for muscle attachment
What is sutural bone
small, flat, irregularly shaped immovable join between flat bone of the skull= sutures
define irregular bone
specialized and unique with complex shapes
examples of irregular bones
vertebrae, hipbones, several skull and facial bones
define short bones
small and boxy bones
give examples of short bones and where they are found
carpals- wrist bones; 8 in each wrist
Tarsals: ankle bones; 7 in each anle
Define sesamoid bones
develop inside tendons; assosciated with joins in hands, feet and knees
How many locations of sesamoid bones are there?
26 locations but varies among people
Give an example of a sesamoid bone
patella
Define articulation
a joint; where two bones come together
define arthritis
inflammation of joints
define process
any projection or bump
Name 4 processes where tendons and ligaments attach
trochanter, tibercle, spine and chest
define trochanter
a large rough process
define tubercle
a small rounded projection
define spine
pointed process
define crest
a prominent ridge
Name 3 processes for articulation with other bones
head (epiphysis), facet, condyle
define head (epiphysis)
expanded and separated from the shaft (diaphysis)by a neck (metaphysics)
define facet
small, flat articular surface (like on a gemstone)
Define condyle
smooth, rounded articular process
Name 2 depressions
fossa, sulcus
define fossa
shallow depression
define sulcus
narrow groove
Name 3 openings
foramen, fissure, sinus
Define foramen
rounded passageway for blood vessels and/or nerves
e.g. of foramen
foramen magnum- where the spinal cord emergences at the base of the skull
define fissure
long cleft (like a crack)
define sinus
a chamber w/in a bone, nomrally filled with air
What is the outside of the bone made of?
compact bone tissue
What is inside the diaphysis of the long bone?
marrow cavity and it has yellow marrow
What is inside the epiphyses of the long bone?
spongy bone
What does spongy bone contain?
trabeculae- branched network of short bone pieces
spaces b/w the trabeculae is red marrow
What is the 2 bone that spongy bone is made of?
trabecular bone and cancellous bone
What is the general set up for bones?
compact bone around the outside
spongy bone on the inside
marrow cavity- space with fat
What is the set up of flat bones?
spongy bone between two compact bones
Define bone matrix
very dense and has minerals
define osteocytes
(bone cells) exists in small places within the matric called launae - organized circular layers that surround blood vessels
Define caniliculi
narrow passageway that connects lacunae to blood vessels and to each other
Define periosteum
mostly dense irregular CT
Where is periosteum not covering?
at joints
How much of the bone mass of the bone matrix is cells?
2 %
What is 1/3 of the weight of bones?
collagen fibers–> stronger than steel when subjected to tension
what is 2/3 the weight of bones?
hydroxyapatite crystals- the minerals in bones
what does the combination of collagen fibers and hydroxyapatite create?
strong flexible and highly resistant to shattering material
define osteocytes
mature bone cells in lacunae
define lamellae
lacunae in circular layers of bone matrix
have long thin cytoplasmic extensions that are contained within canaliculi
function of lamellae
signal other bone cells to build and dissolve bone matrix
participate in bone repair if fractures
define the function of osteoblasts
produce new bone matric- osteogenesis(immature)
mature to osteocytes
define the function of osteoclasts
dissolve bone matrix and releases minerals back into blood circulation–> osteolysis
Describe osteoclasts
giant cells with 50 or more nuclei
related to macrophages
define osteoprogenitor cells
mesenchymal stem cells- divide to produce osteoblasts
assist in fracture repair
Where are osteoprogenitor cells located?
in the inner cellular layer of the periosteum & endosteum
define endosteum
lines surfaces inside fo bones
Effect of minerals as bone matrix is added or subtracted
minerals are added when bone matrix s added
minerals are subtracted when bone matrix is dissolved
What stimulates osteoblasts to build bone matrix?
excercise- weight bearing excercise puts stress on bones–> needed
define bone resorpbtion
same as osteolysis
what is compact bone tissue made out of?
haverian systems/ osteons= consists of several lamelae surrounding a haversian canal aka central canal- contains blood vessels
Define lamella
circular layer of bone matrix; containing lacunae interconnected by canaliculi
define lacunae
contains osteocytes and the canaliculi contains cytoplasmic extensions of the osteocytes
Describe spongy bone tissue structure
more light-weighted than compact bone & able to withstand stresses from many directions
what does spongy bone tissue not have?
haversians/osteons; has concentric lamellae
no central canal or blood vessels
How does spongy bone tissue get its nutrients?
by diffusion from the surrounding bone marrow through canaliculi that open on the surface of the trabeculae
Describe periosteum
has a fibrous outer layer and dense irregular CT and a cellular inner layer
Name 3 functions of periosteum
separates bone from surrounding tissue
a route for circulation and nerve supply to the bone
bone growth and repair
what is on the endosteum?
osteogentitor cells
what does the endosteum line and cover?
marrow cavities, trabeculae, and lines haversian canals
define cartilage models
serve as templates for future bones
when does bone formation start and complete
6 weeks after fertilization and until early adulthood
Two types of ossification
endochondral ossification
intramembranous ossification
define endochondral ossification
starting with cartilage
define intramembanous ossification
starting with a fibrous CT
know steps of endochondral ossification
define articular cartilage
a thin layer of the original cartilage
cushions the end of bones in joints
define epiphyseal cartilage
separates the epiphysis from the diaphysis at metaphysics aka growth plate
describe the process of bone lengthening
- growth of epiphyseal cartilage
2., epiphysis gets pushed away from diaphysis - epiphysis side of the growth plate grows, diaphysis side gets ossified
- growth hormone, sex hormones and thyroid hormones triggers fat bone growth - formation fo bone takes over growth plate- growth stops
- if epiphyseal cartilage is present- still growing
- ossification fo growth plate- visible line in the area is present=epiphyseal line
define late bloomers
kids that spend more time in child phase of growth and ends up being taller than if they have puberty earluer
define appositional growth
bones increase in diamter
- stems in the inner layer of periosteum differentiate into osteoblasts which add layers of circumferential lamellae around the outside of the bone
e.g of bone that does intramembranous ossification
dermal bones;
flat bones of the sull, mandible clavicles, scapulae, hip bones
know steps of intramembranous ossification
process of remodeling
minerals get released from the bone into circulation
minerals are deposited into the bone=shape and internal architecture fo bones are changed
how often does the skeleton get replaced in young adults?
1/5th of the skeleton
issue when heavy metals are in bones
not an issue in bones but if blood can cause problems
radioactive elements in storage of bones
cancer
How does excerise help?
hydroxyapatite crystals in bones develop a small electrical charge when subjected to stress such as exercise resulting in the stimulation of osteoblasts so bones gets stronger in places where there is stress
osteoblasts slow down without exercise
does electricity or stress affect osteoclasts?
no
what happens to the bumps and ridges and tubercles
they get longer to withstand forces due to exercise
define atrophy
bones lose bone mass; reduction in size of a cell, tissue or organ
How much mass does unstressed bones lose?
1/3 of mass
e.g. of unstressed bones
paralyzed, bedridden, astronauts in zero gravity
what happens to unstressed bones
lack of calcium and minerals
bones aren’t doing mineral storage function
e.g of food sources for calcium and phosphorous
milk, cheese, dairy
function of vitamin c
essential for collagen syntheiss and osteoblast differentiation–> specialized and comes into its final form; present in diet
e.g. of foods with vitamin c
citrus fruits
scury disease
vitamin c deficiency; teeth fall otu
function of vitamin D
essential for calcium and phosphorous absorption
define rickets
children deprived of vitamin d; bone don’t develop normally; poorly mineralized flexible bones; bowed legs
define osteomalacia
adults deprived of vitamin d;bones get weaker
define calcitriol
hormone that stiumlates the absorption of calcium and other minerals; absorption from the intestine nd into blood
What creates calcitriol and out of what?
kidneys; out of modified vitamin D molecules
Where does the growth hormone come from?
pituitary gland
Where does the thyroid hormone come from and function?
thyroid gland
essential for normal bone growth throughout childhood
What influences a period of fast bone growth?
effects of GH and thyroid hormones combine with the effects of sex hormones (estrogens and androgens) and epiphseal closure
Define calcitonin?
tones down calcium levels by inhibiting osteoclasts & promotes calcium loss by the kidneys through the urine
What is calcitonin secreted by?
thyroid gland
What does parathyroid hormone do?
raises blood calcium levels through stimulating osteoclasts, decreases rate of calcium excretion by kidney, promotes the synthesis of calcitriol
What are the 3 things that must remain during a fracture?
blood supply to bone, stems in periosteum and endosteum
What is the first step of fracture repair
fracture hematoma: a large blood clot that steops the bleeding but disrupts blood flow and results in some dead bone tissue around the fracture
What is the second step of fracture repair?
cells of endosteum and periosteum divide rapidly
–> results in the formation of internal and external callus
define a callus
made of cartilage and seal over the fracture around the outside and inside of the bone
What is the 3rd step fo fracture repair?
osteoblasts replace the cartilage with spongy bone (cast can be removed about now)
what will new bone tissue always be ?
spongy bone
What is the 4th step of fracture repair?
Osteoclasts & osteoblasts remodel the area, turning the spongy bone into compact bone (several month)
why will the fracture not occur in the same spot again?
can’t break bone in the previously broken spot, maybe different spot
What is a closed or simple fracture?
no break in skin
What are open or compound fracture?
broken bone projects through
risk of excessive bleeding and bad infection
What is a communited fracture?
shattering of a bone
What is a Transverse
fracture?
the break is at a right angle to the long axis of the bone
What is a greenstick fracture?
one side of the bone breaks, while the other side bends; seen in children
define osteopenia
age related reduction is bone mass due to reduction is osteoblast activity while osteoclast activity remains the same
What is commonly affected by osteopenia?
epiphyses, vertebrae, and jaws
fragile limbs, reduced height and loss of teeth
Define osteoporosis
reduction is bone mass so severe that is compromises normal function
What is the vicious cycle
bones broken are typically hip bones, reduction in activity, further bone loss, bones even more easily broken
