Cartilage and Bone Flashcards
Epithelia Tissue
cells which cover free surfaces or form the secretory cells in glands
(skin = stratified squamous)
Muscle Tissue
long thin cells which shorten and cause movement
skeletal, cardiac, smooth (large nuclei, no fibers)
Nerve Tissue
cells with long processes which send impulses around the body
(neurons are the cells that actually transmit the electrical signals, neuroglia are the supporting cells of the neural tissue)
Connective Tissue
Everything else
Varied in structure and function
large number of extracellular fibers (composed of protein collagen)
connective tissue cells secrete all the extracellular matrix components (including collagen)
ex: skin -> faschia, ligament, tendon, fat, bone, blood
Specialized connective tissues
blood
adipose
cartilage
bone
blood
has a fluid extracellular matrix
adipose tissue
lots of cells that store fat
bone
tissue that consists of cells embredded in a mineralized, rigid extracellular matrix
vascular and is constantly undergoing turnover and renewal
Functions of the Skeletal System
structural support - to withstand the forces of gravity and allow upright posture
locomotion - bones and cartilages anchor muscles and act as levers in producing movement
protection - of delicate organs
mineral storage - bones are a resevoir of calcium which is necessry for many metabolic functions in the body. Calcium must be maintained at precise levels and is added to or removed from bones as needed
Blood formation - occurs in bone marrow
Hyaline Cartilage
look for: lacuna (thing in middle) -> cartilage -> matrix with no fibers -> hylaine cartilage (crystal clean)
Semi-rigid tissue consists of cells (chondrocytes) embedded in a rubbery extracellular matrix
Condrocytes are typical protein-secreting cells and secrete the extracellular matrix that surrounds them. They often are poorly preserved in histological preparations and shrink so that they leave an empty space in the matrix
Examples: nose, costal cartilage, trachea
Proteoglycans of cartilage
large, space-filling molecules
highly negatively carged and tightly bind many water molecules
Perichondrium
Layer of dense irregular connective tissue that surrounds the cartilage of developing bone
this layer contains cells which can become new chondrocytes when a cartilage grows
Interstitial Growth
chondrocytes within the cartilage divide and secrete new matrix. The cartilage slowly deforms to accomodate the new matrix. This type of growth occurs mainly in the fetus and children
(cartilage grows in length)
Appositional growth
cells in the perichondrium become chondrocytes and make new cartilage matrix at the surface of the cartilage. This is the main type of growth in adults, but occurs at a very slow rate
(cartilage grows in thickness)
Growth in width of a bone may occur at any time by conversion of cells in the periosteum to osteoblasts
Cartilage
(and aging changes)
avascular - metabolically inactive
nutrition and waste removal occurs by diffusion
this means there is very little turnover of its componenets and has a very poor capacity for repair
aging changes - some cartilages acquaire calcium phosphate deposits in the matrix in older individuals. This makes them brittle and prone to fracture
Elastic Cartilage
similar to hyaline cartilage but has many elastic fibers in matrix (thin)
external ear, epiglottis
thin extracellular fibers
Fibrocartilage
similar to hyaline cartilage but has many more collagen fibers (thick)
has characteristics of both cartilage and dense fibrous connective tissue and is stronger than hyaline cartilage
intervertebral discs and pubic symphysis
osteoblasts
osteoclasts
osteocytes
- bone forming (secrete bone matrix proteins, mostly collagen)
- bone resorbing, secrete enzymes and acid to dissolve the bone matrix
- maintain bones, osteoblasts that become trapped within the matrix, remain in contact with each other through long processes. Mechanosensors (which detect stresses and strains in their own local ara)
intramembranous bone formation
most skull bones form in connective tissues (not really “membranes”)
Bone Matrix
contains collagen and other proteins
calcium phosphate, in the form of hydroxyapatite, precipitates in the matrix several hours after the organic components (proteins) have been secreted
mature bone matrix is about 50% organic material and 50% inorganic minerals
Primary center of ossification
begins in the center of the shaft of a long bone and then moves gradually toward the ends of the bone
Secondary centers of ossification
at the ends of bone
Epiphysial plate
Cartilage between the primary center and the secondary center
All growth in length of a long bone occurs in the epiphyseal plates
Converted to bone after puberty
Outer Bone
Spongy Bone
Bone Marrow
Outer part of all bones is formed by this solid layer
In center, irregular network of spongy bone
Within the spaces of spongy bone, blood-forming bone marrow
Periosteum
Layer of dense irregular connective tissue on the outer surface of a bone. Some osteoblasts are present in this layer
Endosteum
lines the marrow cavity of a bone. Conssits of osteoblasts and osteoclasts.
Lamellae in compact bone
(lamellae –> layers)
Form concentric rings around blood vessels (osteons)
Callus
supports the bone while the fracture is healing
Parathyroid hormone
removes mineral from bone
Calcitonin (from thyroid gland)
causes mineral deposition in bone
Growth hormone
pituitory gland
stimulates growth of the epiphyseal plate cartilage
Estrogen
prevents osteoporoissi in post menopausal women
