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What are some components of the skeletal system?
- Bones
- Cartilage
- Ligaments
- Connective tissues
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What are two types of bones?
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What is Compact bone also called?
Dense or cortical bone
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What kind of tissue is primarily found in Compact bone?
Dense Connective tissue
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What is 80% of bone mass?
Compact bone
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What is spongy bone also called?
cancellous or trabecular bone
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What is 20% of bone mass?
Spongy Bone
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Two types of cartilage?
- Hyaline Cartilage
- Fibro Cartilage
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What kind of cartilage attaches ribs to the sternum?
Hyaline Cartilage
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What is the model for formation of most bones?
Hyaline Cartilage
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What cartilage with stands compression?
Fibrocartilage
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What cartilage forms intervertebral discs, pubic symphysis, and cartilage pages of the knees?
Fibrocartilage
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What anchor bone to bone?
Ligaments
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What anchor muscle to bone?
Tendons
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Bones are _______, _________, and are also a _______ for the body.
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Bones serve as attachment sites for
- skeletal muscles
- soft tissues
- some organs
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What is Hemopoiesis?
process of blood cell production
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Where does Hemopoiesis occur in?
Red bone marrow connective tissue
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Red bone marrow connective tissues contain _____ cells that form blood cells and platelets.
Stem
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What is calcium needed for?
- muscle contraction
- blood clotting
- nerve impulse transmission
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Bone stores…
Calcium and phosphate
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The phosphate stored in bones are used for….
- ATP utilization
- Plasma membrane
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Where in the bones are lipids stored?
yellow bone marrow
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What are the four classes of bone?
- long bone
- short bone
- flat bone
- irregular bone
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Flat bones form…
- the roof of the skull
- scaplae
- sternum
- ribs
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What is the medullary cavity?
Hallow, cylindrical space within the diaphysis
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What does the Medullary Cavity contain?
red bone marrow in children
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what is the tough sheath covering the outer surface of bone?
periosteum
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Periosteum if attached to bone by what?
perforating fibers (numerous collagen fibers)
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Where do artery and vein exit from?
Nutrient foramen
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what is bone marrow?
soft connective tissue of bone
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bone marrow has what 2 parts?
red and yellow
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red bone marrow is also known as...
myeloid tissue
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red bone marrow is hemp-______ which means?
- -poetic
- blood cell forming
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what 3 things do red bone marrow contain?
- reticular connective tissue
- immature blood cells
- fat
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where can you find red bone marrow in children and in adults?
- in children in the spongy bone and medullary cavity of long bone
- in adults its in the axial skeleton, proximal epiphyses of humerus and femur
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what produces yellow bone marrow?
red bone marrow degeneration
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what is yellow bone marrow?
fatty substance
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may yellow bone marrow convert back to red bone marrow?
yes
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what is the primary component of bone?
bone connective tissue
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another word for bone connective tissue is...
osseous connective tissue
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what is bone connective tissue composed of?
cells and extracellular matrix
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what four cells of bone are found in bone connective tissue?
- osteoprogenitor cells
- osteoblasts
- osteocytes
- osteoclasts
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what are osteoprogenitor cells?
stem cells derived from mesenchyme
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what do osteoprogenitor cells do?
produce cells that mature into osteoblasts
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where can you find osteoprogenitor cells?
periosteum and endosteum
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what do osteoblast secrete?
osteoid
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what are osteocytes?
mature bone cells derived from osteoblasts
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what detects mechanical stress on bone?
osteocytes
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whats involved in breaking down bone?
osteoclasts
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what is derived from fused bone marrow?
osteoclasts
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osteoclasts are _____-cytic cells
phagocytic
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what is a collagen protein found in the bone matrix and produced by osteoblast?
osteoid
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ground substance of bone?
osteoid
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what are the some components of the bone matrix?
- osteoid
- calcium phosphate
- hydroxyapatite
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what is compact bone composed of?
osteons
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what are osteons?
small cylindrical structure basic unit of mature compact bone
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what lies central of the osteon and allows blood vessels and nerves to travel through it?
central canal
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what are concentric lamellae?
rings of bone connective tissue surrounding the central canal
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osteocytes are found in small spaces between _____ _______ and hel maintain the ______ _______.
- concentric lamellae (lacunae)
- bone matrix
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what are canaliculi?
tiny interconnecting channels within bone connective tissue
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what is something important canaliculi take part of?
allowing the travel of nutrients, minerals, gases, and wastes between blood vessels and osteocytes
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what are perforating canals?
canal containing blood vessels and nerves perpendicular to the central canal
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what is the difference between external circumferential lamellae and internal circumferential lamellae?
external runs immediatelt internal to bone periosteum where as the internal one runs internal to the endosteum
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what is interstitial lamellae?
lamellae found between osteons
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what are some components of spongy bone?
- trabeculae
- parallel lamellae
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what are trabeculae?
open lattice of narrow rods and plates of bones bone marrow filling space between
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what are parallel lamellae?
lamellae parallel where osteocytes rest between lamellae
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what do osteoclast do?
break down bone
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what do osteoblasts do?
secrete osteoid and build bone
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hyaline cartilage contains no...
bone or nerves
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what are the 3 structures of hyaline cartilage?
- chondroblasts
- chondrocytes
- perichondrium
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what are chondroblasts?
produce cartilage matrix
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what are chondrocytes?
chondroblasts that have been encased within the matrix occupy spall spaces called lacunae
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what is perichondrium?
- dense irregular connective tissue
- covers cartilage and helps maintain its shape
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where does appositional growth occur in cartilage?
on the outside edge out
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where does interstial growth occur?
within the internal regions of cartilage
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the formation and development of bone connective tissue is called?
ossification
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when does ossification occur?
embryo
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intramembranous ossification produces....(4)
- flat bone of skull
- central parts of clavival
- some of the facial bones
- mandible
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when does intramembranous ossification occur?
when mesynchyme becomes thickenes with capillaries
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steps of intramembranous ossification.... (4)
- 1. ossification centers form within thickened regions of mesychme
- 2.osteoid undergoes calcification
- 3. periosteum forms
- 4. lamellar bone replaces woven bone
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what is produced by endochondral ossification?
- bones of the upper and lower limbs
- pelvis
- vertebra
- ends of the clavicle
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whats the steps of long bone development in a limb?
- 1. the fetal hyaline model develops
- -chondroblasts begin to secrete cartilage matrix
- 2. cartilage calcifies, periosteal bone collar forms around diaphysis
- -matrix begins to calcify and chondrocytes die
- -osteoblasts develop and begin secreting osteoid
- -form a layer of osteoid around calcified cartilage shaft termed periosteal bone collar
- 3.primary ossification center forms in the diaphysis.
- 4. secondary ossification center form in epiphyses.
- -hyaline cartilage calcifies and egenerates
- -blood vessels and osteoprogenitor cells enter
- 5. bone replaces cartilage, except articular cartilage and epiphyseal plates.
- 6. epiphyseal plates ossify and form epiphyseal lines
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growth in long bone continues until _____ ______ is converted to the ______ ______
- epiphyseal plates
- epiphyseal line
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when does bone growth and remodeling occur?
during embryologic development
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bone growth in length is termed...
interstitial growth
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bone growth in diameter is termed...
appositional growth
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interstitial growth is dependent upon cartilage growth where?
epiphyseal plate
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what are the 5 continuous zones of epiphyseal plate?
- resting cartilage
- proliferation cartilage
- hypertrophic cartilage
- calcified cartilage
- ossification zone
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where does appositional growth occur?
periosteum
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appositional growth happens because of...
the external circumferential lamellae increases in number
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what increases bone mass?
weight-bearing activities
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what decreases bone mass?
reduced collagen formation unstressed bones
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what are hormones?
molecules released from one cell into the blood
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______ can affect bone composition and growth patterns.
hormones
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4 hormones that influence bone growth?
- sex hormones
- thyroid hormones
- growth hormones
- seratonin
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what is calcium required for?
- initiation of muscle contraction
- exocytosis of molecules from cells
- stimulation of the heart by pacemaker cells
- blood clotting
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what two primary hormones regulate blood calcium?
- calcitriol
- parathyroid hormone
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3 steps of vitamin d activated to calcitriol
- 1. uv light coverts precursor molecule in blood to vitamin d
- 2. vit-D circulates through the body
- -converted to calcidiol by liver enzymes
- -addition of -OH group
- 3. calcidiol circulates in blood
- - converted to calcitriol by kidneys
- -OH added again
- -more calcitriol is formed if PTH is present
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_______ stimulates absorption of ____ ions from the ______ ______ into the _____
- calcitriol
- calcium
- small intestine
- blood
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when is PTH released?
in responce to reduced blood calcium levels
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actions of parathyroid hormone and calcitriol are....
- elevate blood calcium
- return calcium levels within homeostatic range
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calcitriol alone increasing absorption of ______ from where?
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calcitonin is released in response to....
high blood calcium levels
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calcitonin inhibits what in bone connective tissue?
osteoclast activity
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calcitonin stimulates what to increase what kind of loose?
stimulates the kidneys to increase the loss of calcium through urine
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two ways aging affects bone?
- decreased tensile strength of bone
- - reduced rate of protein synthesis by osteoblasts
- bone loss of calcium and other minerals
- -thinner and weaker
- -insufficient ossification, termes osteopenia
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what is osteopenia?
decline of osteoblast activity
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what is osteoporosis?
reduced bone mass
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with age can reduced hormones be a thing?
yes
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what is the term for a break in bone?
fracture
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what are some types of fractures? 4
- stress
- pathalogic
- simple
- compound
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what is pathalogic fractures?
weaking in bone by disease
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what is simple fracture?
broken bone not penetrating the skin
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what is a compound fracture?
piercing overlying skin
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what is the healing time for simple fractures?
2-3 months
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four steps of bone fracture repair?
- fracture hematoma
- -blood vessels torn within periosteum
- fibrocartilaginous callus
- -regenerated blood capilaries infiltrating hematoma
- -fibroblasts producing collagen fibers
- -chondroblasts forming dense connective tissue
- hard callus
- -osteoblasts adjacent to callus producing trabeculae
- -callus replaced by this bone
- -forms a hard (bony) callus
- -continues to grow and thicken
- bone is remolded
- -osteoclasts removing excess bony material
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