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43 Cards in this Set

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Vertebrates have an _____skeleton
endoskeleton, as opposed to the chitinous (fibrous substance consisting of polysaccharides) exoskeleton of arthropods
Five roles of the Vertebrate Skeletal System
1) To support the body
2) Provide the framework for movement
3) Protect vital organs (brain, heart, etc)
4) Store calcium
5) The marrow of flat bones is the location of hematopoiesis, the synthesis of the formed elements of the blood (RBC's, WBC's, platelets)
Two components of the Vertebrate Endoskeleton
1) Axial Component: consists of skull, vertebral column, the rib cage
2) Appendicular Component: consists of all other bones
Connective Tissue
Definition: consists of cells and the materials they secrete
-all connective tissue cells are derived from a single progenitor cell (the fibroblast)
ex: bone
Connective Tissues are derived from
a single progenitor cell (the fibroblast: secretes fibrous material such as collagen, a fibrous protein)
Fibroblast
a single progenitor cell for connective tissue (bone)

the fibroblast: secretes fibrous material such as collagen, a fibrous protein
Examples of fibrous extracellular protein
1) Collagen: a strong fibrous protein
2) Elastin: provides rubber-like elasticity
3 Fibroblast-derived cells
1) Adipocytes: fat cells
2) Chondrocytes: cartilage cells
3) Osteocytes: bone cells
2 Types of Connective Tissue
1) Loose: includes adipose (fat) tissue and material located between cells throughout the body (extracellular matrix)
2) Dense: contain lots of collagen; including: bones, tendons, ligaments
Main Ingredient of the Extracellular Matrix
Proteoglycans: large macropolymers consisting of a protein core with many attached carbohydrate chains (glycosaminoglycans, GAGs), very hydrophilic (always surrounded by a large amount of water)
Why does dehydration result in saggy skin?
Because of decreased hydration of the extracellular matrix
Basement membrane
Definition: sheet of collagen that supports cell layers
-important example of loose connective tissue
Hematopoiesis
The development (via differentiation) of blood cells
2 Primary Bone Shapes
1) Flat- location of hematopoiesis, important for protection of organs
include: scapula, ribs, bones of the skull
2) Long- important for support and movement
include: bones of the limbs
*diaphysis: main shaft of long bone
*epiphysis: flared end of long bone
2 Types of Bone Structure
1) Compact: dense and hard bone
*diaphysis of long bones is a tube composed of compact bone
2) Spongy: porous bone, disorganized structure in which many spikes of bone surround marrow-containing cavities (spikes of bone: spicules or trabeculae)

-most bones: spongy bone surrounded by a layer of compact bone
3 Types of Marrow
1) Bone marrow: non-bony material found in the shafts of long bones and in the pores of spongy bones
2) Red marrow: found in spongy bone within flat bones, is the site of erythropoiesis (formation of RBCs); its activity increases in response to erythropoietin, a hormone made by kidney
3) Yellow marrow: found in the shafts of long bones, is filled with fat and is inactive
Erythropoiesis
formation of RBCs
-occurs in red marrow whose activity increases in response to erythropoietin, a hormone made by kidney
2 Principal Ingredients of Bone
1) Collagen
2) Hydroxyapatite: a solid material consisting of calcium phosphate crystals
-in bone synthesis, collagen is laid down in a highly ordered structure. then, hydroxyapatite crystals form around collagen framework, giving bone its characteristic strength and inflexibility
Basic Unit of Compact Bone Structure
Haversian system or osteon
Microscopic Bone Structure
-in the center of the *osteon=hole called a Haversian (or central) canal- contains blood, lymph vessels, & nerves
-lamellae: surround canal, concentric rings of bone
-canaliculi: tiny channels that branch out from the Haversian canal to spaces (*lacunae)
-osteocyte: in each lacuna, have long processes which extend down the *canaliculi to contact other *osteocytes through gap junctions
Gap Junctions
In bones, allows the *osteocytes to exchange nutrients and waste through an otherwise impermeable membrane
Volkman's Canals
Channels that run perpendicular to Haversian canals to connect *osteons
Cartilage
Strong but very flexible extracellular tissue secreted by cells called *chondrocytes
3 Types of Cartilage
1) Hyaline: strong and somewhat flexible cartilage
ex: larynx and trachea, joints (lined by hyaline cartilage known as articular cartilage)
2) Elastic: found in structures that require support & more flexibility than hyaline cartilage can provide; it contains elastin
3) Fibrous: very rigid and is found in places where strong support is needed
ex: pubic symphysis (anterior connection of the pelvis), intervertebral disks of the spinal column
Unique fact about Cartilage
Cartilage is not innervated and does not contain blood vessels (it's avascular)
Epiphyseal plate
A disk, observed between the diaphysis and the epiphysis during childhood
-cartilage is produced at this plate, epiphysis and diaphysis are forced apart
-@ puberty, androgens or estrogens cause the epiphyseal disk to ossify (& lengthening can no longer occur)
Remodeling
A process by which bone is continually degraded and remade
Osteoblasts
Cells which make bone by laying down collagen and hydrocyapatite
-synthesizes bone until surrounded by bone (space it is left in is *lacuna, and the osteoblast is now an osteocyte)
Osteoclasts
Cells that continually destroy bone by dissolving the hydroxyapatite crystals
-a large phagocytic cousin of the macrophage
What is the result of an increased ratio of osteoclasts to osteoblasts?
Liberation of calcium and phosphate into the bloodstream
What is the result of an increased ratio of osteoblasts to osteoclasts?
Retention of calcium and phosphate in the bones
What do Calcitriol and PTH lead to?
Lead to decreased levels of osteoblasts as opposed to osteoclasts and, thus, Ca2+ increases in serum
Ligaments
Connect bones to other bones
Tendons
Connect bones to muscles
Joint
The point where one bone meets another bone
Synarthroses
Immovable joints
-points where two bones are fused together
Amphitroses
Provide movability and a great deal of support
ex: vertebral joints
Diarthroses
Freely movable joints
ex: ball and socket (hip, shoulder), hinge (elbow)
What are all movable joints supported by?
Ligaments (a short band of tough, flexible , fibrous connective tissue that connects two bones or cartilages or holds together a joint)
Synovial Fluid
Lubricates movable joints
-kept within the joint by the synovial capsule
Articular Cartilage
-Composed of *hyaline cartilage, makes the surfaces of the two bones which contact each other perfectly smooth
What is cartilage susceptible to?
Damage, because it lacks blood vessels
-it is easily damaged by 1) Overuse and 2) Infection
Arthritus
Inflammation of the joints
-leads to destruction of the articular cartilage