Module 3A: Skeletal System Flashcards
what are the three types of cartilage in the skeleton?
- hyaline
- elastic
- fibrocartilage
is ALL cartilage resilient?
yes, it resists compression
relative to bone, does cartilage have higher or lower levels of water and minerals?
high level of water and low level of minerals
- this gives its resiliency towards compressive forces
what does hyaline cartilage do for us?
provides support with flexibility and resilience
which cartilage is the most abundant of the skeletal cartilages?
hyaline cartilage
the different types of cartilage have different amounts of?
water and fiber concentration
- this dictates the behavior and responses they have
what dictates the behaviors and responses that cartilage has?
water and fiber concentration
what are the locations of hyaline cartilage on the skeletal system?
- articular
- costal
- respiratory
- nasal
where is our hyaline articular cartilage?
lying within the joints
where is our hyaline costal cartilage?
where your ribs meet your sternum
where is our hyaline respiratory cartilage?
in our larynx, in our voice box
- all the air that comes in and out is coming through cartilage
the respiratory system is based on what?
cartilage, NOT bone
- specifically- HYALINE cartilage
where is our hyaline nasal cartilage?
the nasal area; the nose
- what we can move in our nose is cartilage
which cartilage has more elastic fibers, elastic or hyaline?
elastic
which cartilage is better able to stand up to repeated bending?
elastic
where can elastic cartilage NOT be used? why?
in places that require structural function. because it is not tough enough
what are the locations of elastic cartilage?
- external ear
- epiglottis (peaks out behind the larynx)
what does your epiglottis do
lifts when you breath in
lowers when you swallow something
- blocks trachea when swallowing so it goes down into the esophagus instead of chocking
which cartilage is more prevalent in the body, fibrocartilage or elastic?
fibrocartilage, but still less than hyaline
what is the strongest cartilage? why?
fibrocartilage because it has a lot of thick collagen fibers
- has great tensile strength
fibrocartilage is going to be located in sites that are?
subject to both pressure and stretch
how are the chondrocytes and the collagen fibers arranged in fibrocartilage?
in parallel rows and this gives it its strength and its ability to resist that compression and pressure
where is fibrocartilage located?
- menisci of knee
- intervertebral disc
- symphysis pubis
when we take a step, about how much weight are we putting up through the limb?
1.5x our body weight
when we are running, about how much weight are we putting up through the limb?
3-7x our body weight/ foot contact
what does our symphysis pubis do?
hold the left and right bones of our pelvis together
are bones an organ?
yes
- made up of many types of tissues
what are the functions of bones?
- support
- protection
- anchorage (attachment point for muscles)
- mineral/growth factor storage
- hormone production
Bone Marrow
- blood cell formation
- triglyceride (fat) storage
what are the two main ways that bones are classified?
- location (axial vs appendicular)
- shape
what is our axial skeleton?
- skull
- vertebral column
- ribs
- sternum
- essentially- the axis of the body; where everything else attached
what is our appendicular skeleton
- limbs, pelvis, shoulder girdle
- appendages
what are the different shapes a bone can be?
- long
- short
- flat
- irregular
- sesamoid
what are long bones?
- longer than they are wide
- have shafts with expanded ends
- ex. femur, humerus
what are short bones?
- mostly cube shaped
- about the same length on each side
- ex. wrist and ankle bones (talus, trapezoid)
what are flat bones?
- thin, flattened but usually curved
- ex. sternum, skull bones
what are irregular bones?
- don’t really fit in any other category
ex. vertebrae
what are the sesamoid bones?
- patella
how the bone is set up is related to?
the shape and location of the bone
what is compact bone?
- dense outer layer
- appears smooth and solid
what is spongey bone?
- the internal layer
- it looks like a sponge in a cross section
- trabeculae form honeycomb-like structure
- contains marrow
what is bone marrow?
the soft substance where blood cells are produced or where we store some fat
what is the traditional structure of short, flat and irregular bones?
- no shaft
- no expanded ends
- spongey bone inside with compact on ends
- trabeculae in the spongey bone
what is the traditional structure of long bones?
- have shafts (called diaphysis)
- have boney ends (called epiphyses)
- have membranes
- have articular cartilage
what is the shaft of a long bone called?
a diaphysis
- this is where compact bone is going to surround spongey bone that has trabeculae and will have yellow marrow in an adult
what is an epiphysis?
the ends of the long bones
- proximal and distal
is a diaphysis or epiphysis broader?
an epiphysis
where is yellow marrow?
in the long bones of adults
what is yellow marrow for?
fat storage
where is the articular cartilage of long bones?
covering the outer edge of the bones to act as a cushion and absorb stress
the membranes that cover the long bones contain what?
the bone stem cells (the osteogenic cells) that become bone cells
what is the endosteum?
the delicate connection tissue that covers internal bone surfaces like in the trabeculae
what are the two long bone membranes?
- endosteum
- periosteum
what is the periosteum?
covers the outside of the long bone except for where the hyaline cartilage is
what are the two types of bone marrow?
- red marrow
- yellow marrow
what is red marrow for?
blood cell production
where is red marrow located?
in trabecular cavities (epiphysis only) of long and flat bones
who has all red marrow and who has very little?
newborns have almost all red marrow and adults have very little
what is yellow marrow for?
fat storage
in adults, yellow marrow can do what if the adult has severe anemia?
turn back into red marrow
who has all yellow marrow and who has very little?
adults are almost all yellow marrow and newborns have very little
how much marrow does short bones have?
a negligible amount. this is because they have little spongey bone
which bone, compact or spongey, has lots of passageways for nerves and blood vessels?
compact
what is the structural unit of compact bone?
Osteon (Haversian System)
what is the structure of osteon?
- long-cylinder parallel to axis of bone acting like tiny weight-bearing pillars
- have groups of hollow tubes (lamellae) of bone matrix rings (like the rings of a tree trunk)
what does the collagen within adjacent lamellae run in?
opposite directions
what helps resist the twisting forces applied to bones?
the collagen within adjacent lamellae running in opposite directions
what are the three different types of lamellae?
- complete
- interstitial
- circumferential
which type of lamellae make up full rings around osteon?
complete lamellae
what is between the osteons?
interstitial lamellae
what is circumferential lamellae?
around the outside of the bone between the endosteum and periosteum
what are the outer vessels located in the endosteum and the periosteum?
- The Haversian (Central) canal
- Volkmann’s (Perforating) canals
where are the Haversian (central) canals located?
core of each osteon; contains nerves/blood vessels
where are the Volkmann’s (perforating) canals for?
they connect Haversian canals to outer vessels
what are canaliculi?
canals connecting adjacent lamellae is an osteon
what does bone growth start with?
osteogenic mitotically active stem cells that will develop into type B osteoblasts
- located in the periosteum and endosteum membranes
what are the three stages of bone growth?
osteoprogenitor cell –> osteoblast –> osteocyte
what are osteoblasts?
bone-forming cells that are active mitotically that will secrete bone matrix, collagen and calcium binding proteins
what happens when osteoblasts become completely surrounded by matrix?
they become type C, osteocytes
what are osteocytes?
mature bone cells that monitor matrix and act as stress sensors
what does osteoclasts do?
break down old cells and absorb surrounding matrix
what is ossification?
bone formation
what are the two methods of ossification?
- intramembranous
- endochondral
what is intramembranous ossification?
bone develops from a fibrous membrane
- ex. clavicle, bones of skull
what is endochondral ossification?
when bone replaces hyaline cartilage
- ex. almost all bones in body form this way
what is the first step of the intramembranous ossification?
the development of the ossification center;
at a site where the bone will develop, osteoblasts clump in the fibrous tissue and form spongey bone and these osteoblast secrete extracellular matrix
what is an osteoid?
an immature bone
what are the four steps of intramembranous ossification?
- development of ossification center
- calcification
- formation of trabeculae
- development of the periosteum
what happen at the calcification step of intramembranous ossification?
the secretion stops, the matrix hardens, it calcifies and the cells are now called osteocytes
what happens at the formation of trabeculae step of intramembranous ossification?
extracellular matrix develops into trabeculae that fuse to form into spongy bone and red marrow will appear
what happens at the development of the periosteum step of intramembranous ossification?
mesenchyme at the periphery of the bone condenses and develops into the periosteum and then we get the layer of compact bone
how does bone grow?
osteoclasts break down bone to form larger ones
- breaks down old cells and absorb the surrounding matrix
what cartilage ossifies to bone?
hyaline
what are the steps of endochondral ossification?
(not important)
- development of cartilage model
- growth of cartilage model
- development of primary ossification center
- development of the medullary (marrow) cavity
- development of secondary ossification
- formation of articular cartilage and epiphyseal plate
what are the steps of endochondral ossification?
(important)
- bone grows on outside of diaphysis
- cartilage in the center of the diaphysis will calcify and develop a cavity
- the blood vessels will invade the internal cavity which becomes spongey bone
- the diaphysis will elongate and officially a medullary cavity will form
- a secondary ossification will appear in the epiphyses and the epiphyses will ossify
- then we get the formation of our articular cartilage and our epiphyseal growth plate
how does bone grow?
with endochondral ossification, it will occur at the end of the bone as well as near the epiphyseal plate of interstitial growth
at what age does the epiphyseal plate become ossified? (epiphyseal plate closure)
age 18 to 21
what is the only way that the diaphysis can increase in length?
the activity of the epiphyseal plate
what do the chondrocytes do as the bone grows?
the chondrocytes proliferate on the epiphyseal side of the plate and new chondrocytes replace the older ones that are destroyed by the calcification process
- the change of cartilage to bone
thus, the cartilage is replaced on this side of the epiphyseal plate so the diaphaseal side (the shaft side of the plate) and the thickness of the epiphyseal plate is able to stay about the same as this bone is growing in length
how do bones maintain the same shape and strength when growing longer?
they need to grow in width (bone remodelling)
how do bones grow in width?
osteoblasts secreting new matrix beneath the periosteum in some areas and the osteoclast-reabsorbing bone in other areas to keep the proper width to match the new length
how much of bone mass is recycled per week?
5-7%
how often is spongey bone replaced?
every 3-4 years
how often is compact bone replaced?
every 10 years
what happens to the bones is calcium sits too long in them?
the bones will become brittle
what are the two sites of control we have for the control of bone growth?
- hormonal
- mechanical stress (tension vs compression)
what are the three considerations of a bone fracture?
- position of bone (displaced vs non-displaced)
- completeness of break (complete vs incomplete)
- skin penetration (closed aka simple vs open aka compound)
what is a comminuted bone fracture?
bone fragments into three or more pieces
- common in the elder because of brittleness
what is a compression bone fracture?
bone is crushed
what is a spiral fracture?
ragged break occurs when excessive twisting forces are applied to a bone
what is an epiphyseal fracture?
epiphysis separates from the diaphysis along the epiphyseal plate
what is a depression fracture?
portion of broken bone is pressed inward
- typical in skull fracture
what is a greenstick fracture
bone breaks incompletely. one side of diaphysis is broken and the other side bends
- common in children
what is a closed (external) reduction?
in a displaced bone fracture repair, a physician manually coaxes bone ends back into position
what is an open (internal) reduction?
in a displaced bone fracture repair, bone ends are secured surgically with pins or wires
what are the steps of a fracture healing?
- blood rushes to the area with repair cells
- fibrocartilaginous callus forms
- bony callus forms (remodeling)
what is osteomalacia?
a bone disorder in adults
- soft/weak bones due to poor mineralization
- vitamin d or calcium deficiency
- will leave you “bowl legged”
- same disorder in children is called rickets
what is rickets?
a bone disorder in children
- called osteomalacia in adults
- analogous disease in children
- more dangerous since bones are growing rapidly
- epiphyseal plate cannot calcify so long bones become enlarged
- seen in poverty and in underdeveloped nations (because diets are poor)
- will leave you “bowl legged”
what is osteoporosis?
bone reabsorption happens at a higher rate than the forming of bone (deposition)
- common in older adults
- bones get more brittle
- more common in women
- treatment: Calcium, Vitamin D, Hormone Replacement Therapy
- prevention: adequate nutrition, load-bearing exercise
the amount of bone tissue in the skeleton (bone mass) can keep growing and accumulating until what age?
late 20s
- you’ll reach your maximum strength and density or peek bone mass
- important to have best strength and density
