SKELETAL SYSTEM Flashcards
thought to be the framework of the body
Skeletal system
The Skeletal System makes up ___% of the body weight.
20
are suited for bearing weight and are the major supporting tissue of the body.
Rigid, strong bones
provides firm yet flexible support within certain structures
Cartilage
are strong bands of fibrous connective tissue that hold bones together
Ligaments
encloses and protects the brain
skull
surrounds and protects the spinal cord
vertebrae
protects the heart, lungs, and other organs in the thorax
rib cage
are strong bands of connective tissue which attach bones to the skeletal muscles to provide movement through contraction
Tendons
are formed when two or more bones come together.
Joints
___ and ___ are the principal minerals stored in the bone and are essential for many physiological activities.
Calcium and phosphorus
are released into the blood when needed and used by other tissues
Lipids
produces red blood cells and platelets and fill the bone cavities of many bones
Red bone marrow
Organic materials of the bone matrix
collagen and proteoglycans
Water-trapping protein molecules that help cartilage be smooth and resilient.
Proteoglycans
Provides flexibility but resists pulling or compression. Essential for the attachment functions of tendons and ligaments and shock-absorption of the cartilage.
Collagen
Component of the inorganic material of the bone matrix
Hydroxyapatite
True or false: the bone becomes brittle if the amount of collagen is reduced.
True
is a rare disorder caused by one of the many number of faulty genes that results in little collagen formation and poor quality collagen
Brittle Bone Disease
3 type of bone cells
osteoblasts, osteocytes, and osteoclasts
Are stem cells which are undifferentiated cells that form into cells suited for specific functions
Osteoprogenitor
Bone building cells for bone formation, repair, and remodeling
Osteoblasts
True or false: osteocytes synthesize collagen and proteoglycans
False - Osteoblasts produces collagen and proteoglycans
Osteoblasts also form ___ which act as templates for hydroxyapatite formation and mineralization of the matrix.
hydroxyapatite crystals
The formation of new bone by osteoblasts
Ossification
Account for 90-95% of bone cells and have a lifespan of 25 years; Produces the components needed to maintain the bone matrix
Osteocytes
houses the osteocyte cell bodies within the bone matrix
Lacunae
are narrow, long spaces housing the osteocyte cell extensions
Canaliculi
Bone destroying cells that break down bone
Osteoclasts
True or false: osteoclasts carry out bone reabsorption which is important in mobilizing crucial Ca2+ and phosphate ions for the use in metabolic processes.
True
are the mature bones which are organized into thin, concentric sheets called lamellae.
Lamellar Bones
Appears porous and has less bone matrix
Spongy bone
True or false: The spaces in between the spongy bone are filled with bone marrow and blood vessels
True
The solid, outer layer surrounding each bone
Compact bone
The ___ or the haversian system is the primary functional unit of the compact bone
Osteon
lined with endosteum and contain blood vessels, nerves, and loose connective tissue
Central canals
Nutrients in the blood vessels are delivered to the ___ and are passed from cell to cell through the canaliculi
Osteocytes
At both ends of this part, growth in length of bones of the arm, forearm, thigh, and leg occurs
Diaphysis
The hollow center of the bone is surrounded by compact bone tissue.
Medullary Cavity
The ends of a long bone composed of mostly spongy bone with an outer layer of compact bone.
Epiphyses
Covers the end of long bones within joints
Articular Cartilage
The growth plate exists between the epiphysis and diaphysis where growth in bone length occurs.
Epiphyseal Plate
Signals the stop in growth of length in bones when it ossifies.
Epiphyseal Line
Site of red blood cell formation and fills the cavities of spongy bone and medullary cavity, especially in fetuses.
Red Bone Marrow
Bone with the largest distribution of red bone marrow
Hip bone
Red Bone Marrow
Yellow Bone Marrow
True or false: Yellow bone marrow completely replaces the red bone marrow in long bones except for the proximal part of arm and thigh bones
True
Connective tissue membrane that covers the outer surface of the bone.
Periosteum
Single cell layer of connective tissue that lines the medullary cavities and smaller cavities of spongy and compact bone. Includes osteoblasts and osteoclasts
Endosteum
Two processes of bone formation
Intramembranous Ossification and Endochondral Ossification
Starts within the embryonic connective tissue membranes; Forms many skull bones, part of the mandible (lower jaw), and diaphyses of clavicles (collarbones).
Intramembranous ossification
locations in membranes where intramembranous ossification begins.
centers of ossification
soft spots that are larger, membrane-covered spaces that have not yet ossified.
Fontanels
All fontanels are closed by ___ years of age
2
Ossifies the cartilage at the 8th week of embryonic development. Develops the bones of the base of the skull, part of the mandible, the epiphyses of the clavicles, and most of the remaining skeletal system.
Echochondral ossification
Processes in intramembranous ossification
osteoblast activity, spongy bone formation, and compact bone formation
Processes in the echochondral ossification
cartilage model formation, bone collar formation, primary ossification, secondary ossification, and adult bone
chondrocytes produce the hyaline cartilage model that has the approximate shape of future bone
Cartilage Model Formation
osteoblasts produce compact bone on the surface of the cartilage model.
Bone Collar Formation
osteoblasts begin to produce bone as they migrate into the calcified cartilage through the blood vessels and transform it into the diaphysis of spongy bone
Primary Ossification
osteoblasts migrate to the epiphysis and continue to form bone to replace the cartilage, except in the epiphyseal plate and articular surfaces.
Secondary Ossification Center Formation
spongy and compact bone are fully developed and the epiphyseal plate becomes the epiphyseal line
Adult Bone
a process where the osteoblasts form a new layer of bone on the surface of old bone.
Appositional growth
Growth in long bones occurs in the ___ which separates the diaphysis from the epiphysis.
Epiphyseal plate
Contains slowly dividing chondrocytes
Zone of Resting Cartilage
Chondrocytes produce new cartilage by dividing and forming columns
Zone of Proliferation
Chondrocytes mature and enlarge
Zone of Hypertrophy
Very thin and contains hypertrophied chondrocytes and calcified cartilage matrix. They eventually die and blood vessels from the diaphysis grow into the area.
Zone of Calcification
Osteoblasts line up on the surface of the calcified cartilage and produce a new bone matrix, which is later remodeled.
Ossified Bone
The closure of the epiphyseal plate to the epiphyseal line occurs between ___ to ___ years of age, depending on the bone and individual
12 to 25
Process where old bone is replaced with new bone
Bone remodeling
Bone remodeling - ___ remove old bone and ___ deposit new bone
osteoclasts, osteoblasts
localized mass of blood released from blood vessels but confined in an organ or a space
Hematoma
mass of bone tissue formed on the fracture site
Callus
Precursor to healed tissue that replaces a clot
Granulation Tissue
mechanism by which the body maintains adequate calcium levels
calcium homeostasis
Critical physiological regulator of many processes to achieve and maintain homeostasis
Calcium
The process of removal of minerals and collagen fibers from the bone matrix in order to be distributed by the blood.
Bone Resorption
Addition of minerals and collagen fibers back into the bone
Bone Deposition
3 regulators of calcium homeostasis
parathyroid, calcitriol, and calcitonin
Secreted by cells in the parathyroid gland. Essential for the maintenance of blood calcium levels within homeostatic limits
Parathyroid hormone
True or false: PTH hormone exerts direct regulatory control of bone cells, especially osteoclasts which are the primary cells for bone-reabsorption
True
___ stimulates the reabsorption of calcium from urine which reduces the amount excreted
Parathyroid hormone
Increases blood Ca2+ levels and is primarily found in the kidney where calcitriol activation occurs
Calcitriol
Increases osteoclast activity and assists PTH in the kidney tubules to prevent Ca2+ removal in the urine
Calcitrol
Inhibits osteoclast formation and activities thus lowering blood calcium levels and decreasing bone-reabsorption
Calcitonin
The average adult has ___ bones.
206
True or false: newborn fetuses have over 400 bones that will fuse later on in life
False: babies initially have 300 bones
4 categories of bone based on shape
Long, short, flat, irregular
Longer than they are wide, they provide movement in the appendages
Long bones
Approximately as wide as they are long, they transfer force between long bones.
Short bones
Relatively thin and flattened, they provide a strong barrier around organs
Flat bones
Have shapes that do not fit into the three categories and have specialized functions such as protection and allowing bending and flexing
Irregular Bones
Main portion of the bone
Body/Shaft
Enlarged (often rounded) end of the bone
Head
Constricted area between head and body
neck
a rounded protuberance at the end of some bones, forming an articulation with another bone
condyle
flat smooth area of the bone which serves as an articular surface
facet
Arm-like bar
ramus
prominent, raised edges of a bone
Crest
Sharp, slender, and pointed area of a bone
Spine
a bulging bony outgrowth of a larger bone
Process
protrusion or eminence that serves as an attachment for skeletal muscles
tubercle/tuberosity
Large tuberosity in the proximal femur
Trochanter
Enlargement near or above the condyle
epicondyle
Narrow ridge that is less prominent
Line
hole in a bone
Foramen
opening or canal in a bony structure
Meatus
Cleft, narrow, and slit-like
Fissure
a depression in a bone which often, but not always, provides stabilization to an adjacent articulating bone
Notch
a furrow or long shallow depression
groove
air-filled cavities in the skull and face bones around the nose
sinus
a depression or hollow usually in between 2 condyles
Fossa
