Connective Tissues Flashcards

1
Q

What are ‘Connective’/’Supporting tissues’?

A

its supports , binds and connects other tissues and organs providing structural and metabolic support of them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

General Properties of CT

A
  • Strength – tensile strength afforded by structural proteins (e.g. various collagens)
  • Space-filling / volume (due to glycoproteins and complex carbs – retain water
  • Elasticity – can return to original shape after mechanical distortion – due to elastin fibrils
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the constituent elements of Connective tissue?

A
  1. Cells
    1. Extracellular Matrix
      * Ground substance: Hyaluronate and proteoglycan aggregates
    • Fibrillar proteins e.g. Collagen fibres and Elastin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Ground substance: highly hydrated – why?

A
  • Composition: ‘Toilet-brushes’ of a proteoglycan core with covalently-bound glycosaminoglycan (GAG) ‘bristles’.
  • These ‘brushes’ bind to long, linear hyaluronate (HA) molecules, to form hyaluronate - proteoglycan aggregates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is CT derived from?

A

is derived from multipotent embryonic mesenchymal cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The mesenchyme

A

is a type of undifferentiated embryonic connective tissue that develops predominantly in the mesodermal layer of the embryo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is Collagen

A
  • Most abundant human protein – 30% of our whole body protein content
  • 28 types of collagen known in humans

Different collagen types form fibrils and fibre, sheets e.g. Type IV or anchors.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

List of the components of CT

A

1 - Cells: difference types
1. Fibroblasts
2. Macrophages
3. Mast cells
4. Plasma cells
5. Adipose cells
6. Leucocytes

2 - Fibers:
a. Collagenous
b. Elastic
c. Reticular

3 - Matrix:
* The *intercellular substance, in which cells and fibres
* Ground substance Hyaluronate and proteoglycan aggregates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Types Of C.T (Depending On Matrix):

A
  • Soft = C.T Proper
  • Rigid (rubbery , firm) = Cartilage
  • Hard (solid) = Bone
    Fluid (liquid) = Blood
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Fibroblast Cells Structure

A

Flat branched cells (spindle-shaped) with basophilic cytoplasm.
* They can divide.
* Old fibroblasts are called fibrocytes . *fibrocytes are mainly inactive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Function of the plasma cells:

A
  1. Formation of proteins of C.T. fibres.

*the cytoplasm of these cells are rich in ribosomes which on the outer surface of Rough ER.

  1. Formation of C.T. matrix.
  2. Healing of wounds.
  3. Responsible for formation of 3 types of fibres (collagen , elastic , reticular ).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Most common cell and found nearly in all types of C.T. proper?

A

Fibroblasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Macrophages
Structure?

A

Basophilic cytoplasm, rich in lysosomes
▪ Irregular outlines (cell membrane)
*pseudopodia of macrophages is the cause of its irregular outlines.

▪ They can divide.
▪ They originate from blood monocytes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the function of macrophages?

A

phagocytosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Mast cells structure

A

cytoplasm contains numerous basophilic cytoplasmic granules.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Function of mast cells

A
  1. Secrete heparin (anticoagulant)
  2. Secrete histamine (allergic reactions)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Active Plasma Cells Structure

A
  • Basophilic cytoplasm with a negative Golgi image.
    • *negative Golgi image : lack of ribosomes around Golgi apparatus.
    • Nucleus: spherical, eccentric with a clock-face appearance of chromatin.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

function of active plasma cells

A

Function: Secretion of antibodies (immunoglobulins).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Structure of Unilocular Adipose Cells:

A
  • Large spherical , with a single large fat droplet.
  • Thin rim of cytoplasm at the periphery.
  • Nucleus: flattened , peripheral.
    *the large fat droplet squeeze the cytoplasm and nucleus to give them their shape.
20
Q

function adipose cells

A

storage of fat

21
Q

Leukocytes (White Blood Cells) structure

A
  • Appear normally in C.T. proper.
  • Neutrophils increase in acute inflammation.
  • Lymphocytes and monocytes increase in chronic inflammation.
  • Eosinophils and basophils increase in allergic inflammation.
22
Q

types of fibre

A

collagen fibres
reticular fibres
elastic fibres

23
Q

structure and function of collagen fibers

A

Made of collagen type I
* Non-branched fibre , arranged in bundles
* Bundles form the branch.
Acidophilic

24
Q

reticular fibres structure

A

Made of collagen type III
* Branch and form a network
* Stained black with silver

25
Q

elastin fibres function

A

Made of Elastin
Branched
Stained brown with orcein

26
Q

How do cells make collagen?

A

RER
Synthesis of pre-procollagen alpha-chains (glycine every third residue allows helical conformation)

Golgi
* Packing into secretory vessels

Cytoplasm
* Constitute exocytosis

Extracellular environment
* Non-helical terminal peptides cleaved
Collagen molecules assemble into fibrils

27
Q

Some Important examples of collagen types

A

Type 1-5

28
Q

Type 1 collagen fibre

A

90% of all collagen. Fibrils aggregate into fibres and fibre bundles e.g. in tendons, capsules of organs and dermis. Organic component of bone.

29
Q

Type 2

A

fibrils do not form fibres, hence form a very fine mesh present in hyaline and elastic cartilage.

30
Q

Type 3

A

Fibrils form branching fibres, (but not bundles) around muscle and nerve cells, and within lymphatic tissues and organs, where they are called reticulin. Also found in the skin in the papillary dermis.

31
Q

Type 4

A

Type 4 – unique sheet form present in basal lamina of basement membrane.

32
Q

Type 5

A

Type 5 - Anchors basal lamina to underlying reticular lamina.

33
Q

Disorders of Collagen Synthesis:

A
  • Ehlers-Danlos
  • Scurvy
  • Osteogenesis imperfecta
34
Q

Type 1 collagen Assembly

A
  • Each collagen subunit is approximately 300nm long and 1.5nm wide
  • Each fibril is composed of staggered collagen molecules with a periodic banding which repeats every 67 nm.

Fibrils assemble into fibres (which are visible under light microscopy), and fibres can assemble into larger bundles.

35
Q

structure of Dense collagenous C.T.

A

Predominance of collagen fibres + fibroblasts.

36
Q

sites of dense collagenous CT

A

Sites:
1- Dense irregular: e.g. dermis of the skin, capsules.

2- Dense regular: e.g. tendons, ligaments.
Function: tough tissue : resistant to stretch

37
Q

Structure of Elastic tissue (Dense)

A

Predominance of elastic fibres (sheets or membranes) + fibroblasts.

38
Q

Sites and function of Elastic Tissue (Dense)

A

Sites:
Large arteries, e.g. Aorta

Function: elastic tissue : stretchable.

39
Q

Structure Reticular tissue (Loose)

A

Predominance of reticular fibres + reticular cells (specialized fibroblasts).

40
Q

Sites and Function of Reticular Tissue

A

Sites:
Stroma of organs: e.g. liver , lymph node , spleen.

Function: structural support.

41
Q

Structure Unilocular adipose tissue (Loose) (white adipose tissue)

A

Structure:
* Predominance of unilocular fat cells.

42
Q

Sites and Function of Unilocular adipose tissue

A

Sites:
* Subcutaneous tissue , especially in:
1. Buttocks.
2. Abdominal wall.
3. Female breast.
* Around the kidney.

Function:
4. Synthesis , storage and release of fat.
5. Supports organs , e.g. kidney.
Heat insulation.

43
Q

Loose Areolar CT Structure

A

❖ Contains all the main components of C.T.P.

❖ all types of C.T. cells & fibers + abundant matrix.

❖ No predominant element in loose C.T.

44
Q

site of loose areolar CT

A

Sites:
e.g. Subcutaneous tissue.

45
Q

Function of the ECM:

A

The connective tissues non cellular portion is known as the extracellular matrix (ECM), giving the physical scaffolding for the cells.

  • The ECM is able to hold water, provide appropriate hydration of the tissue and form part of a selective barrier to the external environment.
    Composition: ‘Toilet-brushes’ of a proteoglycan core with covalently-bound glycosaminoglycan (GAG) ‘bristles’. These ‘brushes’ bind to long, linear hyaluronate (HA) molecules, to form hyaluronat- proteoglycan aggregates
  • *Highly polar, hence attract water (90% of ECM is water)
  • Gel-like, inflexible and resistant to compression (useful in cartilage)
46
Q

ECM dysfunction can result in various medical conditions:

A

Abnormal remodelling of tissues results in alterations in ECM structure and function, which ultimately promotes the development of common diseases such as fibrosis, osteoarthritis, and cancer.

47
Q
A