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Body Logistics > Lecture 10: connective tissue > Flashcards

Lecture 10: connective tissue Flashcards

1
Q

Define what connective tissue is by defining its structure.

A

Made ground substance, fibre and cells

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2
Q

Give 3 functions of connective tissue.

A
  • hold & support organs, skin
  • shock absorber
  • heat insulation
  • protect the vital organs
  • separate tissues
  • transporting substances
  • fuel + storage
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3
Q

Name some examples of the main connective tissue cells.

A
  • chondrocytes
  • osteoblasts/cytes/clasts
  • fibroblasts
  • stem cells/progenitor cells/BM/blood/adipocytes
  • reticulocytes
  • macrophages
  • mast cells
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4
Q

What are the main products of connective tissue?

A
  • fibres
  • wax or gel-like substances
  • GS
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5
Q

Name some examples of fibres you can find in connective tissue.

A
  • elastin
  • collagen 1-4
  • reticulin
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6
Q

Name what ground substance (GS) is made out of and identify an example.

A

Proteoglycans: hyaluronic acid

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7
Q

Describe what these suffixes mean…

  • blast
  • cyte
  • clast
A

Blast: create, grow, make…
Cyte: maintain, finished state…
Clast: destroy, break down…

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8
Q

Extracellular matrix is made of 2 (3) substances. What are they?

A

GS + fibre (+cells)

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9
Q

How can connective tissue be classified?

A

Loose/areolar connective tissue

Dense/fibrous/collagenous connective tissue: irregular or regular

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10
Q

Describe the structure of loose connective tissue.

A

Contains many types of cells: fibroblast, macrophages, adipocytes, mast cells, WBCs

Contains fibres: elastin & collagen

Blood vessels, cells, fibres lie in gel-like GS

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11
Q

What are some functions of connective tissue?

A 
Holds vessels that will supply fluid
Permits cell migration 
Becomes involved in the inflammatory pathways
Packaging around organs
Cushions and stabilises organs
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12
Q

Why are fibroblasts important in the immune system?

A

They are cells involved in healing process and responsible for scar formation.

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13
Q

How are myofibroblasts different to fibroblasts?

A

Myofibroblasts are modified fibroblasts that contain actin and myosin. This allows the healing cells to pull together; causing contraction of the wound to close.

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14
Q

What is the role of a macrophage?

A

They are monocyte derivatives that move in areolar loose tissue (not blood) which phagocytose and become APC to T lymphocytes.

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15
Q

What is the role of a mast cell?

A

Contain many granules: histamines, anticoagulants, cytokines.
They mostly react to allergens by crosslinking their IgE & allergen which releases the granules = oedema.

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16
Q

What are the different types of adipose tissue and give their functions?

A

White adipose = 1 lipid droplet with peripheral nucleus which acts as padding, shock absorber, insulation and energy store.
Brown adipose = >1 lipid droplet with central nucleus which provides insulation and energy storage. NOT PROTECTION.

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17
Q

Why would individuals have more brown than white adipose tissue?

A

Neonates/young children release more heat compared to adults. Brown adipose allows uncoupling of oxidative phosphorylation so more heat is generated and lipolysis is quicker. White adipose breakdown is slower so heat is only generated by shivering.

18
Q

Collagen is the most common protein in the entire body & there are 4 types. Discuss each type and where you would find these collagen types.

A

Type 1: Fibrils->fibres->fibre bundles found in tendons, dermis, organs
Type 2: Thin proteins found only as fibrils in hyaline & elastic cartilage
Type 3: (AKA reticulin) Fibrils->fibres around muscle, nerve cells, tendons and within lymphatic tissues.
Type 4: 6 chain structure found in the basement membrane.

19
Q

Out of all 3 fibres, which fibre is absent in areolar tissue?

A

Reticular fibres which would usually provide a supporting framework; not needed in loose tissue.

20
Q

Knowing what mast cells’ function and secretions are, where would you not find them in the body and why?

A

Mast cells cause oedema and so you would not find these in the brain as this will cause serious damage due to pressure build up in the skull.

21
Q

GS is made up of proteoglycans. What are proteoglycans made up of and how do they help the GS with its function?

A

They are macromolecules with core proteins bound to GAGs (glycosaminoglycans).
GAGs attract H2O as they are polysaccharides. Hence it forms a gel which resists compression.

22
Q

What is the most famous GAG and how is its structure suited to its popular use in cosmetics?

A

Hyaluronic acid can form giant hydrophilic macromolecules which attract a lot of water. Therefore, it will retain a lot of water if applied to the skin.

23
Q

Why would hyaluronate be present in GS of cartilage?

A

Cartilage undergoes a lot of pressure and stress. The hyaluronic acid will make the GS more gel-like so that the cartilage resists compression. Hence, less friction and damage will occur in the cartilage.

24
Q

Describe the arrangement of irregular dense connective tissue. Try to relate the structure back to its role.

A

Many collagen bundles packed closely together due to little GS. The multidirectional packing allows the skin to withstand multidirectional tearing.

The elastin allows for some stretch (again prevent tearing) and for the skin to be restored to its original form after bending.

25
Q

How would you be able to distinguish between a micrograph of areolar and irregular dense tissue?

A

Areolar tissue has peripheral nuclei and the fibres tend to be smaller. On the other hand, irregular dense tissue tends to consist of more elastin the fibres are more close together. Thus, the fibres will look a lot ‘bigger’.

26
Q

Describe the histology of dense regular connective tissue and relate it to it function.

A

There are collagen bundles which will be parallel to one another and densely packed (due to very little GS). Fibroblasts are embedded within the fibrils so that they easily produce new procollagen when needed. This allows for the muscles to have great tensile force in line with the muscle.

27
Q

Aside from the densely packed collagen bundles, how do MSK have great physiological strength?

A

Muscle fibres interconnect with collagen bundles at myotendinous junctions. This interaction results in crosslinks being formed so there is great mechanical strength.

28
Q

Tendons are much stronger compared to muscle based on its relative size. If a person decided to do a 100m sprint on a hot day (after 6 months of no exercise), why would their Achilles tendon possibly snap?

A

Tendons are made of collagen, elastin and mostly water. If the tendon is dehydrated, there is less water in the GS so the collagen is less resistant to force. As a result, more friction would occur between the bundles so are more likely to tear then snap.

29
Q

How are ligaments different to tendons?

A

Ligaments are dense connective tissue between bones, whereas tendons are dense connective tissue between bone and muscle.
Ligaments’ collagen fibres are also wrapped in areolar tissue called fascicles.

30
Q

What is fascia and how is it different to ligaments and tendons?

A

All 3 are made up of fibrous connective tissue. However, fascia’s collagen bundles are presented in a wavy pattern which allows an up & down motion: so resists great force until the wavy pattern is straightened out.

31
Q

How is collagen produced?

A
  1. Proline and lysine need to be hydroxylated to make procollagen.
  2. This is done by collagen peptidases which require cofactor Vit. C.
  3. Fibroblasts then secrete procollagen where it is modified into collagen molecules.
  4. Molecules then bind together to form fibrils.
32
Q

What diseases are associated with abnormal collagen synthesis?

A
  • scurvy
  • Marfan’s syndrome
  • osteogenesis imperfecta (brittle bone disease)
33
Q

What causes scurvy and how would it present?

A

Due to Vit. C deficiency so some collagen fibrils aggregate together and some don’t. Consequently, you get thinner (fragile) & thicker fibres. This leads to irregular collagen fibres.

  • gum disease/tooth loss
  • bruising skin
  • hair loss
  • bleeding
  • poor wound healing
  • weakness
  • fatigue
  • impaired bone development in young
34
Q

How would you treat a patient with scurvy?

A

You would give vit. c supplements and advise more fruits and dark leafy greens in diet. They should recover quite quickly.

35
Q

You are a junior doctor on the ward and a patient has come in complaining of chest pains and breathing problems and hip pain. You notice that they are taller than average; are very thin; have very long limbs and fingers. What is your diagnosis?

A

Marfan’s syndrome.

36
Q

What causes Marfan’s syndrome and what complications can occur?

A

Autosomal dominant disorder where the fibrillin 1 gene is affected so the elastin is abnormal. Some problems that can occur is frequent joint dislocation and they are at risk of catastrophic aortic rupture. Abnormal elastin in the aortic walls will cause them to weaken so they are more likely to rupture (aortic aneurysm).

37
Q

What are the 2 components of elastic fibres?

A

Elastin and fibrillin.

38
Q

What is desmosine and isodesmosine and give their clinical relevance?

A

They are AA found only in elastic fibres. Finding them in the urine means that there is a disease regarding elastic break down.

39
Q

Name the layers of a blood vessel from outermost to innermost.

A 
Tunica externa
Tunica media
Internal elastic membrane
Basement membrane
Tunica intima
40
Q

What is the difference between the the tunica: externa, media, intima?

A

Externa: outermost layer that contains mostly fibrous tissue which prevents the vessel from bursting
Media: middle layer made of elastic tissue and mainly smooth muscle.
Intima: thin, squamous endothelial layer that lines the lumen

41
Q

Why do chronic smokers sometimes have difficulty breathing?

A

Chemicals damage the lung tissue. Therefore the immune system’s response is for neutrophils to release enzymes and destroy that tissue. However, that tissue contains a lot of elastin so destroying that means that it will be harder for the lungs to return to its original form.

42
Q

What is osteogenesis imperfecta and how does it present?

A

AKA brittle bone disease which is an autosomal dominant disease. Due to mutated COL1A gene where:

  • mutated collagen fibres don’t interconnect normally
  • not enough collagen is produced
  • both
  • blue sclera
  • short stature
  • fractured/broken bones
  • hypermobile joints
  • hearing loss (due to ear bones)
  • flat/arched feet

Body Logistics (13 decks)

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