Cartilage & Bone Flashcards

(58 cards)

1
Q

What do chondrocytes manufacture and secreate?

A

Collagenous precurser procollagen–> modified in the ECM into tropocollagen

latter forms various cross-links to form a collagen FIBRIL

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2
Q

Can you see fine fibrillar matrix of cartilage under LM?

A

No

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3
Q

What is the amorphous ground matrix composed of

A

AGGRECAN

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4
Q

Where is the entire amorphous matrix contained?

A

within the spaces between the type 2 collagen fibers

Fibers and amorphous ground substance form a alttice

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5
Q

What is function of collagen and aggrecan?

A

Collagen- provides tensile strength

Aggrecan contains high concentration of negative ions to bind large quantities of water molecules

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6
Q

What is function of cartilage ECM

A

space-holding network ,formed of immobilized water

Serves as a shock absorber, releasing water when under compression and attracting water when the compressive force is removed

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7
Q

Where does cartilage tissue develop from?

A

mesenchymal cells that migrate, aggregate, cndense, and give rise to chondrogenic (precursor) cells

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8
Q

Mesenchymal cells?

A

develop into chondrblasts –> chondroblst secrete ECM around itself –> now completed embedded in ECM in a space called a lacuna!

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9
Q

Mature cell is called?

A

Chondrocyte!

Contain large amounts of RER b/c they manufacture large amounts of collagen

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10
Q

What are the function and location of Hyaline Cartilage? (5)

A
  1. Fetal Skeleton
  2. Anterior Portion of the Ribs (costal cartilage)
  3. Structural support of the trachea and bronchi
  4. Articular surfaces of synovial joints
  5. Epiphyseal (growth) plate in long bone
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11
Q

What is a synovial joint composed of?

A

Fibrous Capsule

synovial membrane (whcih secretes synovial fluid)

Articular surface of hyaline cartilage

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12
Q

Does articular surface have perichondrium?

A

No! It gets diffusion of oxygen and nutrients from synovial fluid

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13
Q

Perichondrium surrounds all cartialge exept where?

A

Articular surfaces

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14
Q

What is the composition of Elastic Cartilage?

A

Type 2 collagen & elastic fibers

Provide an increased amt of flexibility designed to withstand repeated flexiosn and extensions

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15
Q

Where can you find Elastic Cartilage?

A

In structures that must withstand repeated bending,

such as auricle of ear,

external auditory canall,

Estachian tube, epiglottis,

and the larynx

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16
Q

What kind of stain is needed to see Elastic fibers?

A

Not with H&E

Specific Stain is required to definitely identify this tissue, bye staining elastic fibers BLACK

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17
Q

Describe what Elastic cartilage looks like?

A

Covered by perichondrium and contains chondroblasts and chondrocytes in lacunae.

IT also contains the same ECM components as allohter cartalge

Type II colalge, minor colalgens, same amorphous ground substance`

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18
Q

What two components make up elastin fibers?

A

Fibrillin fibers with an elastin core

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19
Q

What kind of fibers are in Fibrocartilage

A

Usual ECM components, also contains TYpe I Colalgen Fibers

Presence of Type I colalgen in fibrocartilage ECM makes it tougher than hyaline or elastic cartilage, but also makes it resistant to compressive forces

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20
Q

Where can you find Fibrocartilage?

A

symphysis pubis

intervertebral disks

menisci of knee joint

attachment points of tendons to bones

Provides resistance to particularly strong forces beign exerted at these locations and it also provides flexibility

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21
Q

What color does it stain?

A

Presence of Type I colalgen fibers makes fibrocartilage stain pink with H&E

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22
Q

Does it have a perichondrium?

A

No

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23
Q

Describe the layers of the intervertebral disck

A

acts as shock abosrber between vertebrae

oval-shaped disk has 2 parts
1. center- nucleus pulposus that contins mesenchymal cells in viscous fluid of hyalaurinc acid

  1. outer regularly arranged concenetrc fibrocartilage layers = annulus fibrosus
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24
Q

In young, how is cartilage repaired?

A

repair form damage occurs through replacement of chondroblasts generated from chondrogenic layer of perichondrium

25
IN adults, ?
Cartilage repair occurs poorly or not at all Hwne cartilage in kenee is torn, natural healing process favors either formatino of scar tissue (Fibrous CT, generated from fibrous layer of perichondrium) or bone deposition
26
Under what conditions favor cartilage formaiton?
when oxygen pressure is low, usually not the case in a wound where blood is bing delivered quickly as part of normal immune and healing repsonses High oxygen concentrations favor development of bone
27
What is a consequence of cardiothoracic surgery?
costal cartilage is severed to open chest ccavity for heart repair-- ribs have to be wired back to sternum one after-effect can be arthritis of rib cage
28
What is bone?
Specialized CT and organ
29
What kind of tissue types are in bone (the organ?)
CT fibers, hemopoietic tissue, nerves, vasculature, lymphatics, fat, cartialge, bone tissue
30
Bone as organs are classified as (4)
1. long bones (upper and lower extremities) 2. short bones (hands and feet) 3. flat bones (skullbones, breastbone) 4. Irregular oones (vertebrae, mastoid bone)
31
What are the functions of bone?
1. Form jointed skeletal system of the bond- ligaments and provide attachemtn sites for sk muscle 2. protect vital organs- skull encase brain, thoracic cage, pelvis protects reproductive 3. Contain bone marrow - new blood cells formed 4. provide reservoir for Ca and Pi ions growth facotrs and other minerals
32
What is the ECM of bone composed of?
1. organic portion that forms template for mineratlized protein
33
What is organic protion called? what does it contain? What kind of fibers ?
Osteoid- contains amorphous ground substance and fibers ground substance is composed of proteoglycans fibers are predominatly Type I collagen
34
Where does their assembly take place?
Extracellulary from precursor molecuels syntehsized and secreted by osteblasts
35
What is the principla mineral component of EC in bone?
Calciumm Phosphate (hydroxyapetite) , present in crystalline form
36
What two methods are used to prepare bone from LM examination?
1. Ground bone method | 2. Demineralization (decalcification)
37
What is the Ground Bone Method?
Bone is thinly sliced and finely ground Calcified matrix is preserved but cellsa re lost
38
What is the Demineralized Method?
bone is fixed, calcium phosphate is removed, and remianing material is embedded, sectioned, and stained with H&E stained Fixation process preserves cells and organic portion of ECM (mostly collagen fibers)
39
What are osteoblasts? waht do they produce?
Basophilic, cuboidal cells taht secrete organic componetn of ECM. Produce ALKALINE Phosphatase, procolalgen, and non-collagenous proteins that have a role in calcification.
40
What stimulates Osteoblasts?
Vitamin D, Calcitonin, estrogen, and grotwht factors The also contain receptors for parathryoid hormone, which inhibits their activity and stimulates osteoclast activity
41
When does calcification begin?
When osteoblast's secretions lower pH around teh cell Alkaline phosphatase rleases free phosphate ions; these combinde with calcium ions and ppt as crystlas of calcium phospahte low pH is required for this step
42
What cells do osteoblasts originate from? Where are they found?
osteoblasts originate from OSTEOPROGENITOR CELLS in teh periosteum and in BM capabe f active cell division Found ining endosteal and periosteal surfaces of actively-growing one and maintain communication with each other by means of gap junction
43
How doe osteoblasts stay in contact? What is prominent in their structure?
Communicate with each otehr thorugh gap unctions and have a prominent Golgi apparatus and rER since they make a lot of cells and rlease large amounts of proteins
44
What are osteoclasts? Function?
Multinucleated macrophae under hormonal control, osteoclast uses low pH and preoteases to digest bone Resorbs bone
45
what do osteoclasts secete?
H+ ions to raise extracellular pH, then secrete acid phosphatase--> dissolves calcium phospahte matrix of bone Also release collagenase which digests old collagen fibers
46
What stimulates osteoclasts?
Stimulated indirectly by Parathyroid hormone (PTH), and inhibited directly by CALCITONIN, which binds to specific receptors on their surface
47
Do osteoclasts begin digestive process extracellulary or intracellulary?
Extracellulary by secreting lysosomal-like enzymes like acid phsophatase and collagenase nto lumen adjacent to their ruffled border
48
What happens during bone remodeling and when does it occur?
Osteoclast resorption, osteoblast activity (matrix formation steoid), mineralization, resting phase Remodleling takes palce during normal bone maintenance, repair of bone fractures and in response to increased bone loading (lifting weights leads to thicker, stronger bones)
49
What are contained in Haversian canacls and Volksmann's canals?
Veins, arteries, lymphatics, nerve processes Broken bones are painful and bone breakage always involves bleeding
50
what are canaliculi
canaclas taht extend between lacunae processes of adjacent osteocytes communicate via gap junctions all osteocytes are conencted to Haverisan canal which provides their nourishemnt
51
What is PERIOSTIEUM
outer covering with two layers, outer, fibrous layer (similar to dense CT0 and inner cellular layer covers external surface of bone, contains a reservoir of osteoblasts for new appositional bone formation attachemtn point for muscles, tendons and ligaments
52
what are Shaerpye's fibers
Type I colalgenous fibers that exend into bone, anchioring it firmly' fibers are found wherever a strong aattachemnt to bone is required attachemtn if furtehr strengthened by thickening of the periosteum wherever bones, tendons, or laigament attach
53
what kind of cellsa re in teh inner layer of periostieum?
contain osteoprogenitor ells which give rise to osteoblasts
54
What are two types of ossificaiton? Two ossficaiton differ with respect to starting material
1 can be mesenhyme | 2. oe XERILfw
55
What does low oxygen levels favor?
development of cartialge
56
What does high oxgyen levels favor?
development of bone
57
What is intramembranous ossification?
bone forms direclty within layer of condensed mesenchyme bone generated from within the MEMBRNAE CARTILAGE is NOT invovled in this process at all Mesencymal cells differentiate directly into OSTEOPROGENITOR celsl (bone precursr ) cells --> osteoblast
58
Periosteal layer
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