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What is the study of the skeletal system called?
Osteology
Are bones organs?
Yes
Bones are made of what 3 things?
Bone tissue, Cartilage, & Dense (collagenous) CT
The Skeletal System is made of what 3 things?
Bones + Cartilage + Ligaments
Bundles of dense regular CT that connect to bone are called...
Ligaments!
How many bones do adults have?
206
How many bones do babies have?
270
What are the 3 parts of the axial skeleton?
-Skull
-Vertebral Column
-Sternum & Rib Cage
What are the 4 parts of the appendicular skeleton?
-Shoulder girdle
-Upper appendages
-Pelvic girdle
-Lower appendages
What are the 6 main bone functions?
-Support
-Protection
-Movement
-Electrolyte balance
-Acid-Base balance
-Blood cell production in red bone marrow
The bone matrix is made of...
Calcium Phosphate (Hydroxyapatite) and other minerals which form crystals around collagen fibers
What protein provides tensile strength?
Collagen
Is bone vascular?
Yes (bones can bleed)
Osseous Tissue is...
Bone tissue
Osteogenic cells are...
Mesenchymal stem cells
Osteogenic cells turn into...
Osteoblasts
Osteogenic cells multiply by...
Mitosis
Osteoblasts _______ bone
Build
Osteoblasts become...
Osteocytes
Osteocytes are found in cavities called...
Lacunae
Small channels that connect lacunae are called...
Canaliculi
What do the canaliculi do?
Connect the osteocytes in the lacunae to each other & connect to the blood supply
Osteoclasts _______ bone
Dissolve
Living bone is constantly being ________
Remodeled
Hydroxyapatite is...
Calcium Phosphate
Trabeculae and red marrow are found in...
Spongy bone
Does spongy bone have osteons?
No
Trabeculae are...
Interconnected strips found in spongy bone
What are Osteons?
Dense cylinders that strengthen COMPACT bone
Spongy bone has strength with ___________ weight
Reduced
Which of these does spongy bone not have?
a) Lacunae
b) Osteocytes
c) Osteons
d) Canaliculi
c) Osteons
Does normal stress over time make bone stronger?
Yes
Compact bone have great _______ strength
Vertical
What are the basic functional units of compact bone?
Osteons
The osteon cylinders run parallel to the ______ axis of bone
long (they're up and down)
The Central Canal is located...
In the center (middle) of the osteon
What does the Central Canal contain?
Blood vessels and nerves
What surround the Central Canal?
Concentric Lamellae (layers)
Concentric means...
One inside the other
Lamellae means...
Layers
Perforating Canals run...
Perpendicular (side to side)
Perforating Canals involve...
The passage of blood vessels, lymphatic vessels, and nerves that run between the Periosteum and the deeper parts in the bone
Rings of bone surrounding a central canal are...
Concentric Lamellae (remember concentric lamellae just means layers wrapping around each other)
What are the 2 types of lamellae?
Circumferential & Interstitial
What type of lamellae is located between osteons and has remnants of broken down osteons?
Interstitial
What type of lamellae is located right underneath the periosteum and encircles the bone's circumference?
Circumferential
The periosteum has ___ layers
2
The OUTER layer of the periosteum is made of...
Fibrous Collagen
The INNER layer of the periosteum is...
Osteogenic
The periosteum covers...
The entire bone surface except the articulating surfaces
True or false: The periosteum is involved in bone growth and repair
True
Does the periosteum have blood vessels and nerves?
Yes
Ligaments connect _______ to _______
Bone to bone
Tendons connect _______ to _______
Muscle to bone
The Endosteum is an incomplete, thin layer of....
Reticular tissue
What lines the medullary (marrow) cavity?
the Endosteum
How many bone shapes?
6
What are the 3 main parts of long bone structure?
-Proximal Epiphysis
-Diaphysis
-Distal Epiphysis
Both Epiphysis's (ends) of long bone have...
Articular cartilage
Which end of the long bone has red bone marrow?
The Proximal Epiphysis
What is in the diaphysis (middle) of long bone?
The shaft and medullary (marrow) cavity with YELLOW bone marrow
What is between the Periosteum and Endosteum of long bone?
The Bony Collar
At the center of long bone there is a...
Medullary Cavity
The bony collar is made of mostly...
Compact bone
The structure of flat bone looks like a...
Sandwich
Compact bone sandwiching spongy bone is found in...
Flat bones
The spongy bone with red marrow is called...
Diploe
Cranial bones are usually what bone shape?
Flat
"Intramembranous" means...
Within/between membranes
Ossification means...
Bone formation
Intramembranous Ossification means
The forming of spongy bone filled with marrow between compact bone
Intramembranous Ossification occurs in...
Flat bones
Mandible
Bone that replaces baby fontanels
The 2 types of Ossification are...
Intramembranous & Endochondral
Ossification begins during the _____ or _____ week of embryonic development
6th or 7th
Endochondral Ossification is when...
Cartilage is replaced by bone
Endochondral Ossification forms ______ ____ the skeleton
Most of
True or False: Cartilage becomes bone
False; Cartilage is REPLACED by bone
There are 6 steps of ______________ Ossification
Endochondral
What happens in step 1 of Endochondral Ossification?
The origin of most bones as Hyaline Cartilage
Ossification begins in step ___ of Endochondral Ossification
2
What happens in Step 2 of Endochondral Ossification?
Perichondrium becomes periosteum & bony collar forms
What 4 things happen in Step 3 of Endochondral Ossification?
-Blood vessels grow into cartilage
-Cartilage calcifies and dies
-Medullary (marrow) cavity forms
-Proximal epiphysis forms
What happens in Step 4 of Endochondral Ossification?
-The Medullary (marrow) cavity enlarges
-The distal epiphysis forms
What happens in Step 5 of Endochondral Ossification?
Bones continue to grow at the Epiphyseal plate
What happens in Step 6 of Endochondral Ossification?
Bones stop growing and the Epiphysial plate closes, leaving an Epiphyseal line
Within the Epiphyseal Plate, bone grows from _________ to _____
Bottom to top
Around what age does the Epiphyseal plate stop growing?
Ages 18-20
Growth in width is...
Appositional Growth
During appositional growth, layers are added to the...
Bony collar
What specifically happens in appositional growth?
Periosteal blood vessels lie inside bony ridges and eventually the ridges fold around the vessels (like a burrito)
During appositional growth, new _______ are formed and the __________ _______ enlarges
Osteons; Medullary Cavity
Do bones have homeostasis?
Yes
Bone homeostasis occurs in response to:
-Physical Activity
-Age
-Nutrition
Bone remodeling allows for...
-Healing after fractures
-Changes in response to mechanical stress
-Acid-base balance
-Maintenance of blood calcium & phosphorus
During bone remodeling, ________ _______ are continually removed and replaced
Calcium salts
The pull of _______ and _______ are important for bone health
Muscles and gravity
Lack of mechanical stress leads to...
Bone atrophy
Weight bearing exercises stimulate...
Bone growth & retention of bone mass
True or False: Exercising at ANY age is beneficial
True!
About what percentage of our calcium is in our bones?
99%
Note 
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