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What are the three types of skeletal
cartilages?
Hyaline Elastin Fibrocartilage TERM 2
Describe the structure of skeletal cartilage.
DEFINITION 2 The structure of skeletal cartilage consists primarily of water, making the cartilage resilient; the cartilage contains no nerves, is non-vascular (contains no blood vessels) and is surrounded by a thin membrane called the perichondrium ; a layer of dense, irregular connective tissue that is vascular and contains nerves. TERM 3
What is the function of the perichondrium?
DEFINITION 3 The perichondrium is the source of blood vessels and limits cartilage thickness; surrounding all three types of skeletal cartilage. TERM 4
What cells make up all three types of skeletal
cartilage?
DEFINITION 4 Chondrocytes; cells that secrete the non-cellular matrix of cartilage (cartilage cells). TERM 5
Describe the structure of hyaline cartilage.
DEFINITION 5 The skeletal cartilage known as hyaline cartilage is the strongest type of cartilage, providing some flexibility and is the most abundant type of cartilage found in the body. Chondrocytes are the cells that make up hyaline cartilage. Collagen is the most prominent fiber that makes up hyaline cartilage; providing mainly support, being very strong and somewhat flexible, accommodating some movement.
What are the four locations of hyaline
cartilage?
Articular: a region of cartilage that covers the bone ends of long bones, enabling the formation of joints (creating a movable joint) Costal: a region of cartilage that connects the ribs to the sternum Respiratory: located within the voicebox and trachea; all having hyaline cartilage Nasal: contained within most of the nose TERM 7
Describe the structure of elastin cartilage.
DEFINITION 7 The skeletal cartilage known as elastin cartilage is very flexible (the most flexible of the three skeletal cartilages) and is made up of the fiber elastin. TERM 8
What are the two locations of elastin
cartilage?
DEFINITION 8 The external ear and The epiglottis (the flap that covers the larynx) TERM 9
Describe the structure of fibrocartilage.
DEFINITION 9 The skeletal cartilage known as fibrocartilage is a cross between hyaline and elastin cartilage. The fibers collagen and elastin make up fibrocartilage; the function of fibrocartilage is to resist heavy pressure/stretch. TERM 10
What are the three locations of fibrocartilage?
DEFINITION 10 The knees The vertebrae, in-between vertebral discs and The pubic symphysis
Describe the Axial Skeleton
The axial skeleton forms the long axis of the body; the skull, vertebral column and rib cage. TERM 17
Describe the Appendicular Skeleton
DEFINITION 17 The appendicular skeleton includes the bones of the upper/lower limbs and the pelvis. TERM 18
How are bones classified?
DEFINITION 18 Shape TERM 19
What are the four classifications by shape?
DEFINITION 19 Long Bones Short Bones Flat Bones Irregular Bones TERM 20
Describe Long Bones
DEFINITION 20 Long Bones have an elongated shaft (diaphysis) and two enlarged ends on either end of the shaft (epiphyses; which means to put on), located either proximal/distal or superior/inferior. The location of long bones are all bones of the limbs (including the arms, legs, fingers and toes).
Describe Short Bones
Short Bones are cube-shaped and are located within the wrist and ankle. TERM 22
What are Seasmoid Bones?
DEFINITION 22 Seasmoid Bones are a special type of short bone, defined by the fact that they form within tendons (the patellar tendon within the patella). TERM 23
Describe Flat Bones
DEFINITION 23 Flat Bones are thin, flat and contain small curves; located within the sternum, scapula, ribs and skull. TERM 24
Describe Irregular Bones
DEFINITION 24 Irregular Bones have a complicated shape; located within the hip bones (left and right ilium making up the pelvic girdle) and vertebrae. TERM 25
What are the five functions of bones?
DEFINITION 25 Support Protection Movement; ligaments attach to bones and muscles attach to ligaments; providing movement Mineral Storage; such as calcium and phosphorus Blood Cell Formation (hematopoiecis); within the bone marrow (red blood cells, white blood cells and platelets)
Describe the Diaphysis
The diaphysis is the long shaft made up of compact and spongy bone; in the center of the shaft is the medullary cavity containing yellow bone marrow; two epiphyseal lines occur at either end of the shaft. TERM 32
Describe Ossification
DEFINITION 32 The organic osteoid (liquid matrix); is secreted by osteocytes (bone cells), calcium and phosphorus are added and over time the osteoid hardens (ossification occurs); the organic liquid changes into firm, hard compact bone. TERM 33
Describe the Epiphyses
DEFINITION 33 The epiphyses (meaning: upon) are located on the ends of long bone; either superior/inferior or proximal/distal. The exterior of the epiphyses is compact bone and the interior is spongy bone, containing red marrow elements; articular cartilage is located on top of the epiphyses and is made up of hyaline cartilage, these are the points of articulation for other bones (coming into contact with other bones to form joints). TERM 34
Describe the Epiphyseal Line
DEFINITION 34 The epiphyseal line is found between the epiphyses and diaphysis and is the growth plate of long bones. Mitosis is happening (in children, up to puberty) within the epiphyseal line, where the cells are dividing and pushing away from each other longitudinally forming a transitional/growth zone. If a fracture occurs in children along the epiphyseal plate; the cells die and don't regenerate, causing a limb to remain short. TERM 35
Describe the
Periosteum
DEFINITION 35 The periosteum is a double membrane consisting of an outer and inner layer; the outer layer is made up of dense, irregular connective tissue and the inner layer is the osteogenic layer (the bone-forming layer). The inner layer (osteogenic layer) contains osteoblasts (bone-forming cells) and osteoclasts (bone-destroying cells). The periosteum provides blood vessels and sharpy's fibers; which are anchoring fibers to underlying bone.
Describe the Endosteum
The endosteum is the inner membrane that lines the canals and internal cavities, containing osteoclasts and osteocytes. TERM 37
Describe the composition of short, irregular
and flat bones.
DEFINITION 37 The composition of short, irregular and flat bones consists of compact and spongy bone; containing a dipole ; a inner layer of spongy bone. The composition also contains both a periostium (external membrane) and a endostium (internal membrane). TERM 38
Where is the location of hematopoiectic tissue
in bone?
DEFINITION 38 Hematopoietic tissue (blood cell-forming tissue) is found within the red marrow (spongy bone) of long and flat bones (also, the red marrow cavities within the epiphyses of long bone); red marrow is the active marrow making erythrocytes (red blood cells) (also aiding in the creation of white blood cells and platelets); the red blood cells bind the protein hemoglobin, attached to the hemoglobin is oxygen (which attaches to the red blood cell) and the red blood cell then carries the hemoglobin/oxygen throughout the body with iron. TERM 39
Red Marrow is...
DEFINITION 39 Active TERM 40
Yellow Marrow is...
DEFINITION 40 Inactive
Describe the Haversian Canal (Central) within
Compact Bone.
The haverisan canal contains blood vessels/nerves that serve the osteon's cells; running through the core of each osteon (the length of bone; supplying blood to bone cells). TERM 47
Describe the Volkman's Canal within Compact
Bone.
DEFINITION 47 The volkman's canal (perforating canal) lie at right angles to the long axis of the bone and connect the blood and nerve supply of the medullary cavity to the central canals; connecting the central (haversian canal) to the periostium (full of blood vessels). TERM 48
Describe Osteocytes within Compact and
Spongy Bone
DEFINITION 48 Osteocytes are mature bone cells that occupy spaces called lacunae, that conform to their shape; monitor and maintain the bone matrix (stress or strain sensors responding to mechanical stimuli) (osteocytes come from osteoblasts). TERM 49
Osteogenic cells
are...
DEFINITION 49 Osteoprogenitor Cells; mitotically active stem cells found in the two membranes: periosteum and endosteum TERM 50
Osteoblasts
are...
DEFINITION 50 Osteoblasts are bone-forming cells, that secrete bone matrix; actively mitotic
Osteoclasts
are...
Cells that actively participate in bone-resorption (the breaking down of bone) TERM 52
Describe the Lacunae and Caniculi within
Compact Bone.
DEFINITION 52 The lacunae are hollow spaces occupied by osteocytes and are connected by hair-like canals called caniculi (little canals) (connecting the lacunae to each other and the central canal: haversian canal). Lacunae are how osteocytes receive nourishment and are wrapped around the central canal, in a circular motion (tree rings). The caniculi help transport waste and nutrients from one osteocyte to another, via the lacunae. TERM 53
Describe Interstitial and Circumferential
Lamellae within Compact Bone.
DEFINITION 53 Interstitial and Circumferential Lamellae aren't connected to the osteons, but wrap around to provide the same thing: strong structure. Interstitial Lamellae lie between intact osteons and are incomplete; Circumferential Lamellae extend around the entire circumference of the diaphysis (prevents twisting of long bone). TERM 54
Spongy Bone is made up of...
DEFINITION 54 Several Microscopic Structures of Bone called: Trebeculae Lamallae Osteocytes TERM 55
Spongy Bone provides...
DEFINITION 55 Give to Bone
What is the chemical composition of inorganic
bone?
Inorganic Bone consists of hydroxyapatites (mineral salts); mainly consisting of phosphorus/calcium and some aluminum/other heavy metals. The hydroxyapatites account for the bone's notable hardness; allowing it to resist compression. TERM 62
What does the term osteogenesis mean?
DEFINITION 62 Bone Development; (the formation of the bony skeleton) TERM 63
What are the two types of ossification?
DEFINITION 63 Intramembrane Ossification Endochaondrial Ossification TERM 64
Describe Intramembrane Ossification and it's
Four Steps.
DEFINITION 64 Intramembrane Ossification is bone developing from a fibrous membrane (a membrane bone); forms the bones of the skull and clavicle. The four steps determine what type of cell is being formed and are: Mesenchymal Cells give rise to Blastic Cells; which give rise to another type of cell; Osteoblasts. Osteoblasts secrete osteoid (matrix, the organic part of bone; bone barf), which is then mineralized and then ossified. Osteoblasts give rise to Osteocytes Osteocytes give rise to a trebeculae network; the cavities within spongy bone The trebeculae gives rise to mature spongy bone; the mature spongy bone is then vascularized (blood vessels form) and red marrow elements are brought in (bringing in red blood cells, white blood cells and platelets) TERM 65
Describe Endochondrial
Ossification.
DEFINITION 65 Endochondrial Ossification is bone developing by replacing hyalin cartilage; forming all of the bones except for the skull and clavicle; this form of ossification is more complex, involving the breakdown and modeling or becoming of new bone (not just giving rise to, but taking mature bone tissue and breaking it down) (hyaline cartilage becomes ossified). *The body is constantly breaking down bone and secreting osteoid matrix for new bone. *At birth, the body is all hyaline cartilage, which becomes a fully ossified skeleton through endochondrial ossification (long bones were cartilage, and then replaced with bone)
Describe the five steps of endochondrial
ossification.
- A bone collar forms around the diaphysis of the hyaline cartilage model (the formation of the primary ossification center)2. The cartilage in the center of the diaphysis calcifies and then develops cavities 3. The periosteal bud invades the internal cavities and spongy bone forms The periosteal bud is a collection of elements; a nutrient artery, veins, lymphatics, nerve fibers and red marrow elements. Also within the periosteal bud; osteoblasts begin to form osteocytes and osteocytes begin to function.
- The diaphysis elongates and a medullary cavity forms (the appearance of a second ossification center in the epiphyses, which becomes the epiphyseal plate)5. The epiphyses ossify; leading to the formation of epiphyseal growth plates TERM 67
What is the summary of endochondrial
ossification?
DEFINITION 67 The hyaline cartilage is being eroded and replaced by bony spicules; ossification chases cartilage formation, along the length of the shaft. TERM 68
Describe Post-Natal Growth in the Growth of
Long Bones
DEFINITION 68 The growth in long bones is along the epiphyseal plate; the growth occurs within cartilage cells (chondrocytes), which are dividing and pushing against the epiphysis on either end; causing the bone to elongate. TERM 69
What is the Transformation Zone?
DEFINITION 69 The transformation zone is the calcification of the matrix; transforming from cartilage to bone. The zone is characterized by cells enlarging and as a result, the lacunae erode and cartilage cells die. TERM 70
What is the Osteogenic Zone?
DEFINITION 70 The osteogenic zone is when dead cells are replaced by live bone cells called osteocytes; this involves the invasion of marrow elements. Osteocytes (mature bone cells) begin forming the spongy bone as well as compact bone; which replaces hyaline cartilage.
Explain Dwarfism
Dwarfism occurs when the epiphyseal plate closes to early and is signified by the stoppage of growth, due to a deficit in hormone release. TERM 77
What are the two bone-remodeling units?
Explain each one.
DEFINITION 77 Osteoclasts: chew up bone; sanding down of bone in preparation of new bone; carried out by the release of lysosomal enzymes that break down bone (old bone) Osteoblasts: secrete matrix (osteoid, bone barf); the soft, chemical composition of bone containing protoglyceans, glycoproteins and collagen TERM 78
When does bone deposition occur and what
are it's needs?
DEFINITION 78 The bone is damaged (undergoes calcification for new bone); the needs of injured bones are Vitamin C and D with collagen, makes it possible for bones to absorb calcium (requires ultraviolet light). TERM 79
What is the osteoid seam?
DEFINITION 79 The site of matrix deposit (bone barf) during a break, crack or damage (osteocytes). TERM 80
What is the calcification front?
DEFINITION 80 The calcification front is the area where bone is soft, when the osteoid is laid down; the osteoid doesn't all calcify at once (the osteoid edges harden first, then the middle)
What is bone resorption and what
accomplishes this task?
Bone Resorption is the breaking down of bone accomplishes by osteoclasts; lysosomal enzymes digest the organic matrix and hydroxyapatites (acids) are converted into calcium salts, which become a soluble form; these then dissolve and make their way into the lymph and blood vessels. Phagocytosis Endocytosis Transcytosis (Translocation) TERM 82
What controls the remodeling of bone?
DEFINITION 82 Hormones; respond to high and low calcium levels TERM 83
What does the Parathyroid Hormone regulate
(PTH)?
DEFINITION 83 The parathyroid hormone responds to low calcium levels; if the calcium levels drop or dip then the secretion of PTH occurs, this stimulates osteoclasts to start chewing up bone and through this process; more calcium is released into the blood.These two hormones act as a brake and gas pedal.Below 9mg, PTH activates TERM 84
What does the Calcitonin hormone regulate?
DEFINITION 84 Calcitonin responds to high levels of calcium, which inhibits the release of osteoclasts.These two hormones act as a brake and gas pedal.Above 11mg, Calcitonin activates TERM 85
What two hormones maintain blood Ca2+
(calcium) levels?
DEFINITION 85 Para-Thyroid Hormone Calcitonin *Normal is between 9-11mg per 100ml of blood
What are the two types of skin penetrations of
a fracture?
Did the bone penetrate the skin? Open (Compound): the bone did penetrate the skin, broke the skin (bleeding, hemorrhaging) Closed (Simple): the bone didn't penetrate the skin, didn't break the skin TERM 92
What are the types of healing and the time of
healing for fractures?
DEFINITION 92 Healing involves the realignment of bone. Closed Reduction: bones are coaxed into place by hand Open Reduction: bones are put in place by screws, pins and wires Immobilization: the use of casts or traction The healing time for a simple fracture is 6-8 weeks. TERM 93
What are the four stages of the repair process
of a fracture?
DEFINITION 93
- A hematoma occurs first in a bone fracture A hematoma is a mass of clotted blood The bone cells begin to die The tissue swells, which is the inflammation response; due to prostoglandins
- A fibrocartilaginous callus forms A soft callus (granulation tissue) begins to form after a few days after the fracture Capillaries grow, giving rise to phagocytic cells that clean away bacteria and debris; characterized by the fact the capillaries were destroyed and broken Osteoid (a fibroblast) is secreted by the periosteum and endosteum; beginning to reconstruct the bone Chondroblasts give rise to chondrocytes; which form cartilage where it needs to be Osteocytes forms spongy bone This mass of repair tissue is called the fibrocartilaginous callus; occuring early in the repair process 3. The bony callus forms; characterized by the cartilaginous callus ossifying (becoming hard), giving rise to a hard bony callus after 2- months4. The bone remodels; all excess formation material is removed after three months, and all membranes/surface structures return to normal.The cast comes off early in the healing process of a fracture due to Wolf's Law; bones will break again easier because no stress or demand was put on it. TERM 94
What is the homeostatic imbalance of bone?
DEFINITION 94 The imbalance between bone formation and bone resorption underlie nearly every disease state; disease is lack of ease. TERM 95
Describe
Osteomalacia
DEFINITION 95 Osteomalacia is soft bones; the mineralization is often inadequate (not enough calcium); the osteoid (soft part) is produced, but calcium salts aren't deposited (lack of proper diet or Vitamin D). The result is bones soften/weaken leading to a child being bow- legged due to any weight being put on the bones; often deriving from insufficient calcium and Vitamin D.
Describe Rickets
Rickets is a type of bone growth deformity characterized by bowed legs, an enlarged skull and an enlarged rib cage; often due to a lack of calcium or Vitamin D. The epiphyseal plates if not calcified, will widen and enlarge; deforming the bone. TERM 97
Describe Osteoporosis
DEFINITION 97 Osteoporosis refers to when bone resorption outpaces bone deposit; bones become fragile and weak. The risk factors for osteoporosis are: Petite body form Insufficient exercise to stress the bones A diet poor in calcium and protein Abnormal Vitamin D receptors Smoking (which reduces estrogen levels) *More common in aged, postmenopausal women. TERM 98
Describe Paget's
Disease
DEFINITION 98 Paget's Disease is characterized by excessive and haphazard bone deposit and resorption. The newly formed bone (pagetic bone) is hastily made and has an abnormally high ratio of spongy bone; causing reduced mineralization and a spotty weakening of the bones. Also, late in the disease osteoclast activity wanes, while osteoblasts continue to work; creating irregular bone thickenings or the marrow cavity being filled with pagetic bone (typically involving the skull, spine, pelvis and femur, increased deformation and pain). The cause is unknown, but a virus could trigger it; it rarely occurs before age 40 and affects 3% of elderly people.
