Bone and Cartilage Flashcards
What is the major type of collagen that composes cartilage?
Type II collagen
What is an isogenous aggregate?
A group of 4-7 chondrocytes, separated by septa
What is the most abundant collagen in CT proper?
Type I collagen
What constitutes appositional growth of collagen?
chondroblasts in the perichondrium differentiate into chondrocytes, and add to existing cartilage
What constitutes interstitial growth of collagen?
Proliferation and hypertrophy of existing chondrocytes
Inflammatory factors and MMPs play what role in the cartilagenous matrix?
Matrix remodeling
What is perichondrium?
A sheath of dense irregular CT that is vascular and contains chondroblasts
Where in the body would you find hyaline cartilage?
respiratory passages (larynx, trachea), articular surfaces of bones, and transiently as a skeletal model and at epiphyseal growth plates
What distinguishes hyaline cartilage from other types?
Its glossy appearance due to the high level (75-80%) of ECM that is water weight
Where in the body would you find elastic cartilage?
The auricle of the ear, eustachian tubes, epiglottis and larynx
What distinguishes elastic cartilage from other types?
The high level of chondrocytes, as well as the dark-staining elastic fibers found in the matrix
Where in the body would you find fibrocartilage?
The intervertebral discs, meniscus of some joints, pubic symphysis, as well as areas of cartilage that have sustained recurrent damage and repair
What distinguishes fibrocartilage from other types?
The presence of Type I collagen fibers, as well as the lack of perichondrium
What is perichondritis?
inflammation of perichondrium; often resulting in pus buildup between chondrocytes and perichondrium which can destroy cartilage
What is familial osteochondritis dissecans?
A proteoglycan loss of function mutation causing disorganized and weak cartilage
What do Haversian canals contain?
nerves, blood vessels, and lymphatics
What are osteons?
lamellae of bone surrounding Haversian canals
What structure joins adjacent Haversian canals?
Volkmann’s canals
What is the role of osteoclasts and osteoblasts in bone remodeling?
Osteoclasts degrade old osteons, and osteoblasts generate new osteons
What is the overriding factor in regulation of bone mass?
calcium mobilization
What is the pathology of osteoporosis?
Osteoclast activity outpaces osteoblast activity
What clinical situations are associated with osteoporosis?
Aging, decreased estrogen in PM women, inactivity, and inability to absorb Ca2+
What is Osteopetrosis?
Decreased bone resorption due to defective osteoclasts
What are the clinical results of osteopetrosis?
Reduced marrow cavity, decreased blood formation, leading to anemia and infection
What is endochondral ossification?
The replacement of a cartilage model with bone
What is intramembranous ossification?
The replacement of loose CT with bone
What types of bones develop primarily through intramembranous ossification?
flat bones, the skull, and the mandible
What type of ossification is responsible for the initiation of bone growth at the diaphysis of the bone collar?
intramembranous ossification
What type of ossification is responsible for a growth in diameter of long bones?
intramembranous ossification
What is the effect of calcitonin on osteoclasts?
Decrease activity
What organ secretes calcitonin?
Thyroid
Howship’s lacunae are formed by what type of cell?
Osteoclast
What type of cell resides IN lacunae, BETWEEN lamellae in bone?
osteocytes
What is the main organic component of bone?
Type I collagen
What is the main inorganic component of bone?
hydroxyapatite (Ca2+ and PO4-)
What is the composition and function of primary (woven) bone?
random collagen fiber orientation; temporary bone to be replaced
What is the composition and function of secondary (lamellar) bone?
parallel collagen fibers arranged in layers; to serve as permanent bone (but is continuously remodeled)
What is the overriding factor for bone formation/resorption?
calcium mobilization
What type of bone occupies that outer walls of bone structures?
compact (corticol) bone
What type of bone occupies the interior of bone structures?
spongy (trabecullar/ cancellous) bone
What is a Haversian system?
an osteon
What differentiates compact bone from spongy bone?
Compact bone has osteons, and therefore requires an internal blood supply; spongy bone is usally thin enough to be nourished from the outside (there are exceptions)
What is the function of periosteum?
To cover the outer surfaces of bone, and provide nutrition and osteoprogenitor cells
How is the periosteum connected to the bone? What type of fibers compose these structures?
Through Sharpey’s fibers; Type I collagen
What effect does high serum calcium have on PTH secretion?
Negative feedback; it reduces PTH secretion
What substance would you predict to see increased in the bone of a patient with rickets?
Osteoid
Osteoporosis can largely be prevented by attaining a high peak bone mass by what age?
30
What effect does PTH have on renal PO4 absorption?
Decreased rate of renal PO4 reabsorption
A mutation that affects the ability of osteocytes to acidiby the resorption lacuna results in what?
Osteopetrosis
What is the effect of PTH on vitamin D activation?
PTH stimulates vitamin D activation
What type(s) of tissue replace the hematoma formed in response to a bone fracture?
Hyaline cartilage and loose CT
What is the effect of somatotropin on the epiphyseal growth plate?
It upregulates IGF-1, which causes an increase in the mitotic divisions of chondrocytes; it also induces maturation of chondrocytes
In what disease of the bone would you most commonly see a decrease in the mineral to osteoid ratio?
Osteomalacia (Rickets)
What disease of the bone is most commonly associated with defective osteoclasts?
Osteopetrosis
While fibrocartilage cannot undergo appositional growth, it instead undergoes what growth process?
Interstitial growth
What structure is formed as the initial step in healing a bone after a fracture?
A hematoma
The anterior divisions of the brachial plexus are responsible for innervating what kind of muscles?
Flexors
The posterior divisions of the brachial plexus are responsible for innervating what kind of arm muscles?
Extensors
Which bone composes the floor of the anatomical snuffbox?
The scaphoid bone
Which anatomical structures are contained within the anatomical snuffbox?
The scaphoid bone, the radial artery, and the superficial radial nerve
PTH has what effect on alkaline phosphatase activity?
Decrease in activity
What is Benign Paroxysmal Positional Vertigo (BPPV)?
Sudden vertigo due to rapid head motion
