Cartilage and bone week 2 Flashcards

Question

True or false: The epiphysis of bone typically contains articular cartilage.

Answer 1

red marrow: hematopoietic yellow marrow: is more fatty. increases with age.

Answer 2

spongy aka trabecular, alveolar, cancellous compact aka lamellar, Haversian, cortical, compacta woven: immature. not very well organized lamellar: mature. is well organized

Answer 3

interconnected network of _trabeculae_ or _bone spicules_ that provide a supporting framework beneath or above compact bone. can remodel in response to stress. marrow permeates the space btwn bone spicules. trabeculae contain entrapped osteocytes. a layer of osteoblasts cover the surface and produce a layer of organic matrix called the osteoid on teh surface of mineralized trabeculae. a similar layer of cells on the inner surface of the marrow cavity forms the endosteum (contains osteogenic cells)

Answer 4

dense outer subunits of bone consisting of calcified layers arranged in concentric layers of lamellae (_osteons_, _Haversian systems_) around a core of vessels and nerves. may lack regular Haversian systems in woven bone (immature bone) more detail about above: Haversian systems/osteons are organized around _Haversian canals_ which contain a neurovascular bundle conisiting of an artery, a vein, and a nerve. _Volkmann's canal_: interconnect Haversian canals. are perpendicular to the longitudinal axis of osteons when picturing a step ladder, can think of Haversian canals as long sides of step ladder and Volkmann's canals as the steps osteoclasts: can be found periodically on trabecullar surface or in erosion pits called _Howship's lacunae_. attachments at their perimeter and ruffled border at the bony surface create an acidic microenvironment for demineralization and lysosomal digestion of organic matrix

Answer 5

resorption cavites are sites of bone removal that create larger spaces intersecting the boundaries of osteons. these cavities are often cross sections of tunnels called _cutting cones_ in which osteoclasts spearhead bone removal at the tip of the cone. attach to bone at their perimeter and ruffled border. release H+ (creates acidic environment) to break down mineral and proteases to break down organic components. attach to bones via integrins (heterodimeric calcium dependent integral membrane cellular adhesion proteins)

Answer 6

after osteoclast activity, new osteons are produced by laying down bone within previous sites of erosion so that the lamellae are laid down the outside in with the newest lamellae immediately surrounding the Haversian canal and the oldest at the perimeter. lamella of complete osteons are called _primary lamellae_. if lamellae are partially eroded, they presist as residual or _secondary lamellae_ btwn fully formed primary osteons.

Answer 7

b. appositional growth bc matrix cannot expand from within

Answer 8

endochondral ossification: bone is formed on an existing cartilage template intramembranous bone formation/ossification: bone is laid down directly without cartilage step

Answer 9

bone formation in dense connective tissue membranes (flat bones of the skull, shaft of long bones). osteoprogenitor cells differentiate from mesenchymal stem cells and being to mineralized their surrounding matrix to form bone. process of osteoprogenitor differentiation to osteoblast and osteoblast secretion of inorganic matrix (osteoid) is regulated by a variety of growth factors and hormones such as bone morphogenic progeins, IGF-1, Wnt proteins, etc.

Answer 10

endochondral ossification takes place in fetal bones and in the growing epiphyses of long bones. is replacing of cartilage with bone. cartilage model provides a flexible structure for growth (interstitial and appositional) and remodeling of the immature skeleton. growth of epiphyseal plate: chondrocytes in deeper layers of epiphyseal cartilage can proliferate to produce elongation of bone. as new cells are produced, however, they proceed on a program that leads to their replacement by bone. the steps occur in a series of zones as follows (epiphysis to diaphysis): zone of reserve cartilage zone of proliferation: chondrocytes reproduce. where growth takes place zone of hypertrophy: cells begin to die zone of calcified cartilage: dead cells become calcified zone of vascular invasion, bone deposition, and resorption: where endochondral ossification takes place. causes longitudinal growth. osteoblasts in the marrow cavity lay down bone on residual calcified cartilage

Answer 11

genetics, hormones, growth factors (excess growth hormone leading to IGF-1 and somatomedin excess causes acromegaly). cartilage hypertrophy and death is also regulated by hormones and factors such as thyroid hormone.

Answer 12

Primary centers of ossification are formed from initial invasion of blood vessels. secondary centers of ossification are formed above the epiphyseal growth plate from secondary invasion of blood vessels (occurs a little later in life). secondary centers of ossification are a prelude to the cessation of growth during whic the entire growth plate is replaced with bone. steps in bone growth in secondary center of ossification are the same as in primary center of ossification: cartilage death, calcification of cartilage matrix, invasion by blood vessels that brings in osteogenic cells, then bone formation within cartilage model

Answer 13

Fibrin in the blood clot at the fracture site first produces a scaffold for organization of fibroblasts as in a scar. These generate a _cartilaginous callus or union_. The soft callus undergoes a transformation (same as occurs in ossification-cartilage death, calcification of cartilage matrix, invasion of blood vessels that bring in osteogenic cells, bone formation) to a vascularized bony callus. subsequent remodeling can make the fracture site grossly indistinguishable from orininal bone if fracture is properly reduced. see slide 46 of notes for visual

Answer 14

characterized by chondrocyte death and loss of joint cartilage, inflammation of synovial membranes, narrowing of joint space, thinckened subchondral bone, and development of osteophytes (disease of whole joint). result is a painful non-functioning joint. pain comes from surrounding tissue: bone, synovial membrane (cartilage is avascular)

Answer 15

porous bones. decreased bone mass related to: -decrease in estrogen and decreased bone matrix formation (reason for increased risk of osteoporosis in post-menopausal women bc stop actively making estrogen. estrogen comes from aromatase coversion of androgens to estrogens) decreased vitamin D and calcium absorption in alcoholic cirrhosis decreased vitamin D, hypercalcemia, and secondary hyperparathyroidism in renal disease trabecular areas are more susceptible age related but is also pathological

Answer 16

skeletal disorder associated with thickening and weakening of bones related to disregulation of osteoclastic and osteoblastic activity. have excessive bone turnover and have mostly woven (immature) bone-weaker bones. turnover is localized and area of skin is warm due to cellular activity. etiology is unknown but may be viral

Answer 17

group of disorders characterized by failure to form normal mineralized matrix-excessive osteoid presence-soft bone. is called Ricket's disease in children. due to Vitamin D deficiency.

Answer 18

characterized by hypermineralization of bones. bones are very dense and results in mechanically incompetent limbs

Answer 19

group of inherited disorders due to mutation in type I collagen. can be null allele mutation (Type I, least severe type) or structural mutations (typically substiution of glycine, results in more severe forms-Type II (lethal), Types II and IV). thin delicate bones, short stature, multiple fractures

Cartilage and bone week 2 Flashcards

(46 cards)