1
Q
Fascia
- what is it made of?
- what does it do?
- special note
A
- irregular fibrous connective tissue
- tissue protection
- considered its own system and has own drainage
2
Q
How is it different that tendon/ligament/aponeuroses?
A
-less parallel, more disorganized, more dense
3
Q
Benefits of fascia
A
- allows for vasculature and nerves to pass through
- permeates entire body, allowing for communication
- groups muscles, which reduces friction
- creates compartments; control spread of infection
4
Q
Disadvantages of fascia
A
- permeates entire body, can allow for metastasis and infection to easily spread throughout body
- local damage can eventually lead to systemic damage; (muscle attachment and compensation)
- creates compartments: blocked off areas can be exposed to increased pressure, leading to cut off of blood and nerve supply, leading to cellular death
5
Q
Types of fascia
A
- Faniculous adipose
- Axial
- Meningeal
- Viceral
6
Q
Faniculous adiposis
- other name
- derive from
- location
- function
A
- superficial fascia/ sub cu
- somatic mesenchyme
- covers entire body; adipose layer right under skin
- used for insulation, cushion, outermost layer that binds body together
7
Q
Axial fascia
- other name
- derive from
- location
- function
A
- deep
- somatic mesenchyme
- around muscles; continuous with appendicular fascia; on tendons/ligaments/and bones
- makes up perimysium, epimysium, endomysium of muscles; as well as muscle compartments
- allows for protection and ease of motion by providing surface for muscles to slide over each other
8
Q
Meningeal fascia
- other name
- derive from
- location/subtypes
A
- neural
- lower-mesoderm and upper- neural crest
- duramater, leptomeninges (arachnoid & pia) epineu, rium: fascia that wraps around nerves
9
Q
Visceral
- derive from
- location/subtypes
A
- splanchnic
- surrounds all body cavities
10
Q
What cell types are in fascia?
-name and function (5)
A
- Myofibroblasts: Make collagen, Secrete ground substance, respond to mechanical stress and pro-inflammatory cytokines, helps with contraction, presents antigens
- Macrophages: phagocytic, APC, activate fibroblasts, promote differentiation of myofibrils by secreting cytokines and TGF-beta
- Mast cells: pro-inflammatory (histamine), stimulates fibroblasts, causes worsening fibrosis
- Collagen, lamin, fibronectin: provide structure
- Elastin: allows for flexibility
11
Q
Tissue repair for acute injury
A
injury occurs—transient TGF beta expressed—myofibroblasts develop—increased collagen synthesized—normal wound repair
12
Q
Tissue repair with chronic injury
A
persistent injury occurs—sustained TGF beta expressed—myofibroblasts develop persistently—excess collagen synthesized—fibrosis—restriction of local structures
13
Q
Collagen formation
A
- In ER: synthesis of pre and pro collagen; hydroxylation of lysine and proline, glycosylation, and disulfide bond formation
- In golgi: package and secretion of collagen
- Enzymatic removal of most of non-helical domain of pro-collagen by procollagen peptidase forming tropocollagen
- tropocollagen line up head to tail and lysyl oxidase cross links them forming collagen fibril
- Side by side linking of collagen fibrils by FACIT collagen and proteoglycans forms collagen fibers
14
Q
What is co-enzyme of lysyl hydroxylase?
A
Vitamin C- scurvey acid
15
Q
What is secreted form of collagen type I?
A
Procollagen which is changed into tropocollagen by procollagen peptidase
16
Q
What is FACIT collagen?
A
type of collagen that is also a proteoglycan and forms collagen fibers by linking collagen fibrils
17
Q
Where are elastic fibers found?
A
Lung and elastic arteries
18
Q
Synthesis of elastin
A
- Fibrillin secretes microfibrils
- Microfibrils act as scaffolding upon which elastin is then deposited by fibrillin and accumulates around the microfibrils, making up the elastic fiber,
19
Q
Location of synthesis of elastin
A
- Intracellular: Elastin is transcribed by DNA; prolyl is hydroxylated and then secreted
- Extracellularly: Elastin is excised by tropoelastin protease, tropoelastin is formed by three elastins being bound together forming desmosine, tropoelastin then put on microfibrils; lysyl oxidase crosslinks elastin fibers to microfibrils creating elastic fiber
20
Q
Desmosine
A
- formed when elastin cross links
- formed by condensation of four molecules of lysine into a pyridinium ring.
21
Q
Marfans syndrome
- cause
- effect
A
- caused by dysfunction of firbillin
- usually need aortic valve replacement
22
Q
Role of proteoglycan in ECM
A
- Binds water
- Allows the diffucion of small molecules
- Acts as lubricant
- Barrier
23
Q
What is a somite?
-when is it formed
A
- Segmented unit formed by mesoderm that eventually divides to make different cell tissues of body
- Formed at Day 20 of pregnancy
24
Q
Divisions of a somite?
A
-sclerotome and dermamyotome
25
Divisions of a dermamyotome
- myotome
- syndetome
- sclerotome
26
What produces tendons and ligaments
-syndetome
27
Transcription factor for formation and maturation of tendons from syndetome
-scleraxis: induces COLIa1 and Tendomodulin
28
Tenocyte
- tendon cell, made from elongated fibroblasts
| - cytoplasm is stretched between collagen fibers
29
Fascicle
- bundle of collagen fibers
| - multiple fascicles produce a tendon fascicle
30
Endotenon
- wrap around fascicles
| - consist of thin sheet of connective tissue made up of collagen and elastic fibers
31
Epitenon
-wrap around multiple fascicles (tendon fascicle)
32
Principal collagen in tendon and ligaments
-Type 1--consists of 2 alpha1 chains and 1 alpha2 chain
33
Collagen that regulates structure of tendon/ligament
Type: V, XII, XIV
34
What proteoglycans are present?
Decorin, biglycan, fibromodulin, lumican
35
What glycoproteins are present?
Tenomodulin-- made by scleraxis
| Tanacin-- made by mechanical stress
36
Difference in position of fibers in tendon vs ligament
-tendon collagen fibers must align with tension adjacent to muscle and ligament fibers are arranged in a range of directions because they must resist separation of bones in more than one direction
37
Types of tendon injuries
- acute ruptures
| - chronic degenerative injury
38
Four steps of tendon healing
- main type of collagen used
- time
- Inflammation; includes neutrophils, macrophages, increased circulation; hours to days
- Reparation (proliferation), type III; days to weeks
- Remodeling (consolidation), Type III; weeks to months
- Remodeling (maturation), Type I; months to years
39
Are tendons and ligaments avascular?
-No, except with ACL and PCL which are located in joint and therefore have limited access to tissue since they are surrounded by synovial fluid
40
Enthesis
- function
- made of
- joins tendon/ligament to bone
| - fibrous tissue or fibro cartilage
41
Myotendinous junction
specialized region located at the muscle-tendon interface that represents the primary site of force transmission.
42
Does fibrocartilage have blood supply?
yes, but fairly limited
43
ACL vs MCL
-ACL is intracapsular (will heal slower because surrounded by synovial fluid with limited vascular supply), -MCL is extracapsular (will repair more quickly due to increase of blood vessels, inflammation)
Unit 2: LGS
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