Skeletal System (Exam 2) Flashcards
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Function: protection
Skull protects the brain
Vertebrae protect the spinal cord
Rib Cage protects the thoracic cavity viscera
Function: storage
Bones are the major support tissue of the body
Cartilage- firm yet flexible support
Ligaments- attach to bones and hold them together
Function: storage
Ca+2- needed for blood clotting and for electrical signaling in the heart
Phosphorous- needed for ATP synthesis and DNA production
Function: blood cell production
Bone marrow- location of the rbc, WBC, and platelet production
Functions
Support Protection Movement Storage Blood cell production
Cartilage
Consists of special cells called chondroblasts that produce new cartilage matrix
Chondrocyte
When the secreted matrix surrounds the condroblast
It matures
Lacunae
The space a chondrocyte occupies
Perichandrium
A double layered connective tissue sheath that covers cartilage
Outer layer- dense regular connective tissue with fibroblasts
Inner layer- made mostly of chondroblasts
Appositional growth
Growth from the outside
Chondroblasts lay down new matrix on the outside of the tissue
Interstitial growth
Growth from the inside
Inner chondrocytes rapidly divide, expanding the cartilage from within
General bone characteristics
206 named bones
Each bone is an organ
Made of living tissue (can grow and repair)
Axial skeleton
Function: protection and support
Skull, rib cage, vertebral column
Appendicular skeleton
Function: movement
Upper and lower limbs, shoulder and pelvic girdles
4 bone shapes
Long
Short
Flat
Irregular
Long bones
Longer than they are wide
Most bones of the upper and lower limbs
Short bones
A wide as they are long
Bones of the wrist and ankle
Flat bones
Thin, flat, usually curved
Some skull bones, sternum, ribs, scapula
Irregular bones
Odd shaped
Vertebrae, patella (sesamoid bone)
Long bone structure
Diaphysis Epiphysis Epiphyseal plate Medullary cavity Periosteum Endosteum
Diaphysis
Shaft that forms the long axis
Formed mostly of compact bone
Epiphysis
Knobs on the end of long bones
Composed mostly of spongy/cancellous bone
Outer covering of compact bone
Epiphyseal plate
Hyaline cartilage between the epiphysis and the diaphysis
Area of growth
At the end of the growth it is transformed into bone and is called the epiphyseal line
Medullary cavity
In the diaphysis of the long bone
Children- contains red marrow
Adults- contains yellow marrow
Periosteum
CT membrane covering the outer surface of bone
Outermost: dense, irregular CT
Innermost: osteoblasts, osteoclots
Sharpey’s fibers
Osteoblast
Bone forming cell
Osteoclot
Bone resorbing cell
Sharpey’s fibers
Secure tendons and ligaments to periosteum
Endosteum
CT membrane lining inner bone surfaces
Flat bone structure
Usually no epiphysis or diaphysis
Contains spongy bone called diploe
Compact bone on the outer surface
Short and irregular bone structure
Spongy bone center (trabeculae and marrow)
Compact one on the outer surface
Osteon
The structural unit of Compact bone
Lamellae
Circular layers of the bone matrix
Compact bone
Haversian canal
Passage way for blood vessels and nerves
Compact bone
Canaliculi
Small canals that connect the lamellae to each other and to the central haversian canal
Allows nutrient and waste exchange for the osteocytes
Compact bone
Ossification (osteogenesis)
Bone development
Begins 8 weeks after conception
Long bones at birth……
Are well ossified except for the epiphyseal plate
Complete ossification at the end of the growth period
Bones of the skull don’t begin to ossify until……
The 10th week of gestation
Not completely ossified at birth
Final ossification at 2 years of age
Fontanels
Fibrous membranes holding the bones of the skull together before ossification
Bone growth
Happens in length
New bone is formed on the surface of cartilage
Occurs at the epiphyseal plate
4 zones of the epiphyseal plate
Zone of resting cartilage
Zone of proliferation
Zone of hypertrophy
Zone of calcification
Zone of resting cartilage
Nearest to the epiphysis
Contains randomly arranged chondrocytes that are slowly dividing
Zone of proliferation
2nd zone
Chondrocytes producing new cartilage through interstitial cartilage growth
Rapid division
Zone of hypertrophy
3rd
Chondrocytes produced in zone 2 (proliferation) mature and enlarge
Zone of calcification
Consists of cartilage matrix mineralized by Ca+2
Hypertrophied chondrocytes die
Blood vessels inner ate the area
CT surrounding blood vessels contain osteoblasts
They deposit new bone matrix on the surface of the calcified cartilage (appositional growth)
Factors affecting bone growth
Nutrition
Hormones
Vitamin D
Needed for absorption of Ca+2 from the small intestine
Deficiency in children can lead to rickets
Adults with the inability to metabolize vitamin D can develop osteomalacia
Rickets
A disease resulting from reduced mineralization of the bone matrix
Causes bones to “bow”
Osteomalacia
Softening of the bones as a result of Ca+2 depletion
Vitamin C
Necessary for collagen synthesis by osteoblasts
Deficiency can result in scurvy
Scurvy
Characterized by ulceration and hemorrhage of skin because of lack of normal collagen in CT
Hormone at regulate the exchange of calcium between blood and bone
Calcitonin
Parathyroid hormone
Calcitonin
Synthesized and secreted by the thyroid gland
Promotes the incorporation of Ca+2 into bone from blood
Sensitive to estrogen levels
Lots of estrogen=lots of calcitonin release=lots of Ca+2 incorporated into the bone
Menopausal women may develop osteoporosis
Osteoporosis
Brittle bones due to a decrease in Ca+2 deposition
Parathyroid hormone
Synthesized and secreted by the parathyroid gland
Signal for release is low plasma calcium levels
Mobilizes Ca+2 from the bone into the blood
