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64 terms

Skeletal System

2.2
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Skeleton
our supporting structure
The skeletal system includes:
bones and associated cartilage, tendons and ligaments
Why are bones resilient?
because of their elastic protein matrix, and strong because of mineral salts deposited in this matrix
The skeleton works together with ____
to create movement
muscles
Bones are made of ______ _______
living tissues
The stone like appearance comes from _________________
mineral salts like calcium phosphate
The 5 functions of the skeletal system are: ___________________
Support surrounding tissues
Protect vital organs
Provide levers for muscles to pull on generating movement
Manufactures blood cells (hematopoiesis)
Stores mineral salts (calcium, phosphorus) and fats
Poiesis means: __________
forming
The skeletal systems connective tissues are: ___________
cartilage
ligaments
tendons
Cartilage
Environment in which bone develops in fetus
found at ends of bones and in joints
Provides smooth surface for bone to bone areas
Ligaments
attach bones to bones
Tendons
attach muscles to bones
Bone develops from: _____________
osteoblast cells
Osteoblast cells originate in the: ___________________
periosteum and endosteum of the bone.
Osteoblasts mature to become: ____________
osteocytes
Deposition of bone depends on: ____________
strain or pressure on the bone (exersize)
Step 1: Broken Bones
A broken bone stimulates osteocytes (mature osteoblasts) to proliferate.
Step 2: Broken Bones
They secrete large quantities of protein matrix, to form new bone
Step 3: Broken Bones
Osteoclasts are present in bone cavities, derived from the immune system they cause bone reabsorbtion, and remodelling.
Step 4: Broken Bones
Osteoclasts remove bone from the inner side and so remodel bone as after a break and can make a crooked bone straight
The two types of ossification are: _______ and _______
Intramembranous
Endochondrial
(both result in cancellous and compact bone)
Maintaining Bone requires calcium whose concentration is controlled by 2 hormones of the endocrine system:
Parathormone
Calcitonin
Parathormone
causes calcium release into blood
Calcitonin
results in calcium storage in bones
What happens to excess calcium?
excreted by kidneys and digestive system
Cancellous bone means: _______
spongy bone
Intramembranous Ossification
Dense connective tissue membrane is replaced by inorganic salts like calcium, forming bones.
This connective membrane becomes the periosteum, over a layer of compact and a layer of spongy bone.
Only cranial bones are formed this way, complete ossification of the skull is not complete until fontanels close after birth.
Endochondral Ossification
This is when bone develops inside cartilage environment.
Osteoblasts become completely surrounded by protein matrix and become mature bone cells or osteocytes
Produces all other bones of the body
Ossification
forming new bones
By end of 3 months fetus skeleton is completely formed but mostly cartilage
Begins ossification and grows as osteoblasts invade cartilage
Compact bone
Dense and strong
Contain "Haversian canals"
Blood vessels run parallel to surface of the bone
These are surrounded by concentric rings of bone (lamella)
Between rings of bone are Lacunae cavities containing osteocyte connected to the central haversian canal by canaliculi.
Horizontal open areas contain blood vessels and fluid that nourish bone cells (osteocytes)
Functions of havesian cannals:
dense and strong with Haversian systems of central canals surrounded by rings of bone. Rings separated by lacunae, connected by canniculi. Horizontally blood vessels run through these canals bathing osteocyte with 02 and food, excreting waste
. Cancellous or spongy bone
Found at ends of long bones and forms the center of all other bones
Spongy appearance created by meshwork of bone (trabeculae) with spaces filled with bone marrow
What else does Cancellous bone do?
Function as open spaces where bone marrow filled with red bone marrow performs hemapoesis. In adults found in vertebrae, sternum, pelvis, end of humerus (upper arm) and femur (thigh). Areas decrease with age.
Bone Marrow is found in:
the spaces of certain spongy or cancellous bones
Red marrow whose functions is...
Hematopoiesis (formation of RBC, WBC & Platelets). Contains blood cells in all stages of development.
Red marrow is found in the:
ribs, sternum, vertebrae, and pelvis
Yellow Marrow is:
connective tissue containing fat cells.
Yellow Narrow is found:
chiefly in shafts of long bones.
Bones are classified by these 4 shapes:
Long
Short
Flat
Irregular
Structure of a long bone includes:
Diaphysis
Metaphysis
Epiphysis
Epiphyseal growth line
Diaphysis
shaft filled with yellow marrow
Metaphysis
flared portion
Epiphysis
extremity
Epiphyseal Growth Line
where longitudinal growth occurs
Longitudal growth of bones for girls stops at what age?
15
Longitudal growth of bones for boys stops at what age?
16
Maturation and remodeling of skeleton continues till _____ for women and men.
21 years
Short bones
Lack a long axis- consist of spongy cancellous bone covered by thin compact layer.
Shaort bones have a:
Somewhat irregular shape.
Short bones are NOT:
merely shorter versions of long bones.
Flat Bones:
Thin bones found wherever need for extensive muscle attachment.
The shape of a flat bone is:
usually curved
Where do you find flat bones?
sternum, ribs, scapula, parts of pelvic bones skull
What shape do irregular bones have?
Very irregular
Examples of irregular bones are:
vertebrae, ossicles of ear
Irregular bones are:
Spongy bone enclosed by thin layers of compact bone.
What shape is a Sesamoid bone?
small rounded bones
Sesamoid bones are:
enclosed in tendon and fascial tissue
Sesamoid bones are found:
located adjacent to joints
Examples of the Sesamoid bones are:
Patella is largest, some wrist and ankle bones
Processes are:
any obvious boney prominences
Examples of Processes are:
spine, condyle, tubercle, trochlea, trochanter, crest, line, head, neck
Fossae
any depressions or cavity in or on a bone
suture, foramen, meatus, sinus, sulcus
Functions of fossa and processes include:
muscle attachment, articulation, passageways