Chapter 11.6 - Skeletal System Flashcards
Invertebrate skeletons belong to:
organisms without bones, especially backbones
axial skeleton
skull, vertebral column, rib cage
appendicular skeletons
bones in the appendages, pectoral and pelvic girdle
what are the different types of bones in the endoskeletal system?
- flat bones
- short bones
- long bones
- sesamoid
- irregular
Distinct features of long bones
Epiphyses The diaphysis A medullary cavity Metaphyses Epiphyseal plates
Shaft of a long bone is called:
diaphysis
Bumpy ends of long bones
epiphyses
True or false: long bones have a hollow diaphysis
false - filled by medullary cavity containing spongy bone (yellow bone marrow)
Outside of epiphyses have:
articular cartilage. covers compact bone to form synovial joints
How many types of synovial joints are there?
6
Name the types of synovial joints
- ball and socket
- hinge
- plane
- pivot
- condylar
- saddle
Function of hyaline cartilage
cushions joints at the end of long bones, absorbs shock
What structure connects adjacent Haversian systems to the periosteum?
Volkmann’s canals
Which layer(s) of the periosteum contain(s) osteoprogenitor cells?
cambium layer
When is the primary ossification center established?
when osteoblasts invade the calcified center of the cartilage model
How does parathyroid hormone respond during times when blood calcium levels are low?
PTH increases calcium when it is low in the blood by stimulating osteoclasts
What covers the outside portion of the diaphysis?
periosteum
What term describes the canals that connect lacunae and Haversian canals of a single osteon?
canaliculi
Diarthroses
synovial joints between bones that fully move
Where can osteoclasts be found?
howship’s lacunae
What is not a component of a synovial joint?
elastic cartilage
Components of matrix of hyaline cartilage
elastin, chondroitin sulfate, collagen
What type of cartilage is found in the intervertebral discs?
fibrous cartilage
Where do bone cells that are supplied nutrients from Haversian canals reside?
lacunae
What are the components of the cartilaginous matrix secreted by chondroblasts?
collagen; elastin
Where is the Achilles tendon located?
back of lower leg
A basketball player suffers a severe tear in his Achilles tendon. Which of the following will occur at the site of injury?
tendon repair process involves the recruitment of inflammatory cells and fibroblasts from outside the tendon tissue to the injury site
Fibroblasts synthesize:
Extracellular matrix and collagen
___ play a critical role in adhesion formation and wound healing
fibroblasts
A tear in the Achilles tendon results in a weaker connection between:
muscle and bone (not between bone and bone - that’s if a ligament is torn)
What layer covers the surface of cortical bone?
periosteum
If you look inside epiphyses, you would see:
spongy bone with red bone marrow
When do epiphyseal plates ossify?
when pubertal hormones signal for calcification and apoptosis
What direction do epiphyseal plates grow?
towards metaphyses
short bones are ____
cuboidal
Function of short bones
provide support with very little movement
Example of long bone
femur, radius, ulna
Example of short bones
bones in the wrist
Flat bones
cortical bone surrounding spongy bone in the middle
Example of flat bones
sternum, skull
Sesamoid bones are embedded within ____
tendons
Sesamoid bones function
increases muscle’s leverage on the bone it is attaching to
Example of sesamoid bone
patella
Irregular bones composed of:
thin cortical layers surrounding abundant cancellous interiors
Example of irregular bone
pelvis and spine
What allows bones to support our weight?
the density of cortical bone
Microstructures in cortical bone:
Osteons Haversian canals Lamellae Lacunae Volkmann's canals Canaliculi
___ are considered the functional unit of cortical bone
osteons
Describe structure of osteons
multi-layered cylinders that extend parallel to the bone’s long axis
In the center of osteon is:
Haversian canal
Function of haversian canals
contains blood cessels to supply nutrients to various types of bone cells living in lacunae
Lacunae
small spaces between lamellae that house bone cells
True or false: lacunae are independent units
false - they connect to each other/haversian canal via canaliculi
Volkmann’s canals function
connect adjacent haversian systems to the periosteum which supplies the bone with blood and nutrients
____ is the inner network of bones
cancellous bone (spongy bone)
True or false: cancellous bone contains osteons
false
Cancellous bone contains:
web of trabeculae that soap up bone marrow like a sponge
Osteoprogenitors
immature precursor cells that mature into osteoblasts
Osteoblasts have ___ nucleus/nuclei
1 (mononucleate)
Function of osteoblasts
- build bone
- secrete proteins and collagen that make osteoid
- make an enzyme to create hydroxyapatite
Osteoblasts mature into ____ once they:
osteocytes; once they secrete enough bone matrix that they are trapped by it
Osteocytes are:
highly branched cells that communicate with other cells to maintain bone
Where can you find osteocytes?
in lacunae
Osteoclasts have ___ nucleus/nuclei
many (multinucleated)
Osteoclasts are derived from:
monocytes
Function of osteoclasts
chew through bone (resorb bone)
Where are osteoclasts found?
Howship’s lacunae
True or false: once made, bones cease to remodel and stay as is
False - bones undergo lifelong remodeling
Primary mechanisms that affect bone remodeling:
- parathyroid hormone
- Vitamin D (calcitriol)
- Calcitonin
Which mechanisms decrease blood calcium levels?
calcitonin (tones down blood calcium)
Which mechanisms increase blood calcium levels?
- parathyroid hormone
2. calcitriol (vitamin D)
Parathyroid hormone (PTH) is secreted by:
Parathyroid gland
PTH stimulates:
osteoclasts
Calcitonin is secreted by:
thyroid gland
Vitamin D function in blood calcium levels:
increases calcium reabsorption in the intestines, provides negative feedback to PTH secretion
Organic component of bone matrix:
osteoid
Osteoid contains:
type 1 collagen fibers and proteins
Function of osteoid
gives bones slight flexibility and tensile strength
Inorganic component of bone matrix:
hydroxyapatite
Hydroxyapatite is made of:
calcium, phosphate, water crystallized
Embryonic ossification types:
intramembranous and endochondral ossification
Steps of intramembranous ossification
- osteoblasts secrete osteoid, creating osteocytes (ossification center forms in mesenchyme)
- Osteocytes form trabeculae, gets wrapped by blood vessels creating periosteum
- cortical bone begins to grow between periosteum and trabeculae
What bones are formed via intramembranous ossification
Flat bones
Endochondral ossification steps
- cartilage model created at week 8
- center of cartilage model starts to calcify
- week 12 - osteoblasts and capillaries begin to invade calcified center – creates primary ossification center
- secondary ossification created at epiphyses, osteoclasts chew out inside of diaphysis
What bones are made via endochondral ossification
long bones
Fibrous connective tissues include:
tendons, ligaments, periosteum and endosteum
Tendons connect:
muscle to bone
Ligaments connect:
bone to other bones
What is the periosteum?
protective fibrous membrane that covers cortical bone (except at epiphyses where you find articular cartilage)
Periosteum has _ sub layers:
2; fibrous layer, inner cambium layer
True or false: fibrous layer of periosteum is highly innervated and vascularized
true
Cambium layer has ___ that allow for attachment of:
collagen fibers; periosteum to the cortical bone underneath
True or false: fibrous layer of periosteum contains osteoprogenitor cells
false - cambium layer contains osteoprogenitor cells
Endosteum
single layer membrane that lies between cortical and cancellous bone
Endosteum lines the:
- medullary cavity
- surrounding cancellous bone of epiphyses
- lining cavities of Haversian/volkmann’s canals
Cartilage is not:
vascularized or innervated
Chondroblast
build cartilage
When do chondroblasts mature into chondrocytes?
When they become trapped by the matrix they create
Where are chondrocytes found?
cartilaginous lacunae
What do chondroblasts secrete?
collagen and elastin
Types of cartilage:
hyaline, fibrous, elastic
Hyaline cartilage made of:
chondroitin sulfate, collagen, elastin (glassy appearance)
Where is hyaline cartilage found?
between the ribs and sternum, in the nose, and the trachea
Fibrous cartilage function
provides rigidity and resists tension
Where is fibrous cartilage found?
intervertebral discs, knee meniscus
Elastic cartilage
similar to hyaline cartilage but has a lot more elastin proteins
Where is elastic cartilage found?
ears, epiglottis
Synarthroses
dense, fibrous joints between bones that do not move
Amphiarthroses
cartilaginous joints between bones that partially move
Diarthroses
synovial joints between bones that are fully movable
Which type of joint is unstable and accounts for many injuries?
Ball and socket
What do synovial joints contain?
Bones
Articular cartilage covering opposing epiphyses
Ligaments
Fibrous joint capsule
Synovial fluid lubricant within joint cavity
