Test 3 - Bones and Skeletal Tissues Flashcards
Why are bones considered organs?
because they contain several different tissues
- osseous tissue, nervous tissue, cartilage, epithelial tissue (lining blood vessels), and fibrous C.T lining cavities
functions of bones
- support
- protection
- movement
- mineral storage
- blood cell formation
- energy storage
support
form the framework that supports the body and cradles soft organs
protection
provide a protective case for the brain, spinal cord, and vital organs
movement
provide levers for muscles
mineral storage
reservoir for minerals, especially calcium and phosphate
blood cell formation
hematopoiesis occurs within the red marrow
energy storage
yellow marrow
in embryos, the skeleton is predominantly composed of?
hyaline cartilage
in the adult, most of the cartilage is replaced by?
more rigid bone (ossified cartilage)
a typical piece/structure of cartilage has?
cartilage
perichondrium
cartilage
connective tissue which contains no nerves or blood vessels
perichondrium
a layer of dense irregular ct that surrounds the cartilage
perichondrium acts llike
a girdle to resist outward expansion when the cartilage is subjected to pressure
cartilage consists of?
water (60-80%) and is very resilent
three types of cartilage tissue that occurs in the body
- hyaline cartilage
- elastic cartilage
- fibrocartilage
cartilage is a connective tissue that consists of?
cells called chondrocytes and an abundant extracellular matrix
hyaline cartilage
most abundant type of cartilage
in hyalin cartilage each chondrocyte occupies a cavity called?
lacuna
the only type of fiber in the matrix of hyaline cartilage is?
collagen which forms networks that are too thin to be seen with a light microscope
function of hyaline cartilage
provides support through flexibility and resilience
where are hyaline cartilage found?
articular cartilage costal cartilage nose trachea larynx
elastic cartilage
similar to hyaline cartilage but its matrix contains many elastic fibers along with the delicate collagen fibrils
function of elastic cartilage
very elastic and able to tolerate repeated bending
where are elastic cartilage found?
epiglottis and outer ear
fibrocartilage contains?
rows of thick collagen fibers alternating with rows of chondrocytes, each of which is surrounded by a layer of cartilage matrix
function of fibrocartilage
resist both strong compression and strong tension forces
where are fibrocartilage found
ligaments
intervertebral discs
menisci (knee
a piece of cartilage grows in two ways, what are they?
appositional growth
interstitial growth
appositional growth
- growth from the outside
- chondroblasts in the perichondrium produce the new cartilage tissue by actively secreting matrix
interstitial growth
- growth from within
- lacunae-bound chondrocytes inside the cartilage divide and secrete new matrix expanding the cartilage from within
when does cartilage stop growing
in the late teens when the skeleton stops growing, and chondrocytes stop dividing
skeleton is made up
bones that are connected at joints or articulations
joints or articulations
- the location at which two or more bones make contact
- they allow movement and provide mechanical support
the skeleton is subdivided into two division which are?
axial skeleton
appendicular skeleton
axial skeleton
those bones that lie around the body’s center of gravity
appendicular skeleton
the bones of the limbs or appendages
how many total bones make up the human skeleton
206
the bones of the adult skeleton are composed of ?
two basic kinds of osseous tissue that differ in their texture
- compact bone
- spongy (trabecular) bone
compact bone
dense outer layer of bone
- looks smooth and homogenous
spongy (trabecular) bone
internal network of bone composed of small bars of bone and lots of open space filled with bone marrow
bones are further classified on the basis of their relative gross anatomy into what four groups?
long, short, flat and irregular
long bones
such as the femur and phalanges
- longer than they are wide, generally consisting of a shaft with heads at either end
short bones
- tarsals and carpal
- cube shaped and contain more spongy than compact bone
flat bones
- bones of skull are generally thin with two waferlike layers of compact bone sandwiching a layer of spongy bone
irregular bones
- vertebrae
- bones that do not fall into one of the above categories
structure of a typical long bone
contains:
- diaphysis
- epiphysis
- epiphyseal plates
- epiphyseal lines
diaphysis
shaft of a bone composed of compact bone
epiphysis
- end of long bone
- composed of a thin layer of compact bone that encloses spongy bone
the joint surface of each epiphysis is covered with?
a thin layer of articular cartilage (hyaline)
epiphyseal plates
a disc of hyaline cartilage that grows during childhood to lengthen the bone
once the long bone has stopped growing what happens to epiphyseal plates?
replaced with bone and appear as thin, barely discernible remnants - epiphyseal ilnes
what is the difference between bone and cartilage?
bone tissue is well vascularized
- 3-11% of the body’s blood is in the skeleton
the main vessels serving the diaphysis are?
the nutrient artery and a nutrient vein
nutrient foramen
- opening
- opening into the canal which gives passage to the blood vessels of the medullary cavity of the bone
the nutrient artery
- runs inward to supply the bone marrow and the spongy bone
2. branches outward to help supply the compact bone
medullary cavity
- marrow cavity
- the hollow central cavity of the shaft that is a storage region for adipose tissue or yellow marrow
what blood cells sometimes arise from yellow marrow?
white blood cells
at birth all bone marrow is?
red. witih age more is converted to yellow
within long bones red marrow is located in?
the spongy material
what arises in the red marrow?
RBCs, platelets, and most white blood cells
in case of severe blood loss
the body can convert yellow marrow back to red marrow in order to increase blood cell production
marrow is also contained in the?
the spaces between the trabeculae of spongy bone
periosteum
a connective tissue membrane that covers the diaphysis
what are the 2 sublayers of periosteum
- superficial layer of dense irregular CT which resists tension placed on the bone during bending
- a deep osteogenic (bone produciint) layer that abuts the compact bone and contais two cell types
the two cell cell types of osteogenic
osteoblasts
osteoclasts
osteoblasts
- bone generators
- bone depositing cells
osteoclasts
- bone breakers
- remodel bone surfaces throughout our lives
the periosteum is secured to the underlying bone by?
perforating fibers (sharpey’s fibers)
perforating fibers
- sharpey’s fibers
- thick bundles of collagen that run from the periosteum to the bone matrix
the periosteum also provides?
insertion points for the tendons and ligaments that attach to a bone
- dense perforating fibers
why does it hurt when you break a bone?
it’s innervated
why does a bone break cause profuse bleeding?
its vascularized
the periosteum is richly supplied with?
nerves and blood vessels
- nerves and blood vessels travel through the periosteum and invade the bone
articular cartilage
covers the epiphyseal surface in place of the periostem
articular cartilage is composed of?
hyaline cartilage which provides a smooth surface to prevent friction at joint surfaces
what covers the internal bone surfaces of long bones?
thin connective tissue membrane called endosteum
endosteum
- coves the spongy bone and lines the central canals of osteons
- osteogenic..containing both osteoclasts and osteoblasts
structure of short, irregular and flat bones
have much same composition as long bones
- periosteum covered compact bone externally
- endosteum covered spongy bone internally
specific to structure of short, irregular and flat bones
they lack a diaphysis and a marrow cavity
diploe
the internal spongy bone in flat bones
compact bone appears solid in naked eye bye in microscopic examination?
reveals that it is riddled with passageways for blood vessels, lymphatic vessels, and nerves
Osteon (bone)
- or haversian system
- important structural component of compact bone
- long, cylindrical structures oriented parallel to the long axis of the bone and to the main compression stresses
function of osteon
weight bearing pillars
what is an osteon
group of concentric tubes resembling rings of a tree trunk in cross section
each ring of an osteon is a?
lamella
lamella
a layer of bone matrix in which the collagen fibers and mineral crystals align and run in a single direction
the fibers and crystals of adjacent lamellae always run?
in rougly oppiste directions
- this alternating pattern is optimal for withstanding torsion or twisting stressing
through the core of each osteun runs an?
endosteum-lined canal called the central canal or haversian canal
the central canal contains?
a. blood vessels: supply nutrients to the bone cells of the osteon
2. nerve fibers
perforating canals
- volkmann’s canals
- lie 90 degrees to the central canals and connect the blood and nerve supply of the periosteum to that of the central canals and marrow cavity
osteocytes of compact bone
mature spider-shaped bone cells taht are essential for maintaining bone matrix
osteocytes of compact bone occupies?
small cavities in the solid matrix called lacunae (littles lakes) andn their spider legs occy thin tubes called canaliculi (little canals)
the canaliculi run through?
- little canals
- runs through the matrix connecting neighboring lacunae to one another and the nearest capillaries
structure within canalliculi of compact bone
the extension of neighboring osteocytes touch each other and form gap junctions
how does nutrients diffuse from one osteocytes to the next throughout the entire osteon?
via direct cell transfer
why? because the bone is too hard to diffuse gasses and nutrients
each trabecula of spongy bone contains?
several layers of lamelae and osteocytes but is too small to contain osteons or vessels of its own
the osteocytes receive their nutrients from?
capillaries in the endosteum surrounding the trabecula
chemical composition of bone
has both organic and inorgainc ompotnents
organic components
- 35% of bone tissue mass
- includes: cells, fibers, and ground substance
- contribute to the flexibility and tensile strength that allow bone to resist stretching and twissting
inorganic components
-65% of bone tissue mass
-Consists of hydroxyapatites
(mineral salts)…primarily
calcium phosphate.
-Provide bone with exceptional
hardness (resist compression)
osteogenesis
- ossification
- the process of bone-tissue formation
osteogenesis leads to?
a) the formation of the bony skeleton in embryos
b) bone growth until early adulthood
c) bone thickness, remodeling, and repair in adults
before 8 weeks of embryogenesis
the skeleton of the human embryo
consists only of hyaline cartilage and some membranes of
mesenchyme
Week 8 of embryogenesis
Bone tissue first appears in week 8 and eventually replaces most
cartilage and mesenchymal membranes in the skeleton.
Note: The unborn baby is now called a fetus
intramembranous ossification
when bone develos from mesenchymal membrane without 1st
imtramembranous ossification forms?
membrane bone
- most of the flat bones of the skull and the clavicles
endochondral ossification
when bone forms by replacing hyaline cartilage
endochondral ossification forms?
endochondrial bone
- grow through adolescence via epiphyseal plate
