Lecture 6 Flashcards

1
Q

Connective tissue Function

A
  1. Connecting framework of the body
    a. Continuous with other basic tissue types
    b. Stroma – connective framework of body organs and glands
    c. Medium for diffusion of metabolites
  2. Supportive framework of the body
    a. Cartilage, bones, ligaments and tendons
  3. Protection and defense
    a. Immune and inflammatory responses
    b. Tissue repair after injury
  4. Fat storage
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2
Q

Connective tissue components

A

• Extracellular matrix (ECM) and cells

• ECM contains:
– Ground substance

– Fibers
– It generally contains blood

and lymphatic vessels

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3
Q

What is depicted by the Green and blue arrows

A
  • Ground substance (Blue)
  • Fibers (collagen and elastic) (Green)
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4
Q

Ground Substance

A
  1. Glycosaminoglycans (GAGs)
  2. Proteoglycans:
  3. Glycoproteins
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5
Q

What are the arrows pointing to

A
  • Collagens: tensile strength
  • Elastic fibers:ability to return to original shape
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6
Q

What type of fiber is shown in the image

A

Collagen I fibers

Light microscopy of type I collagen fibers stained pink. F: fibroblasts.

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7
Q

What type of fiber is shown in the image

A

Collagen I fibers

Electron microscopy of type I collagen fibers:

Fibrils show periodicity at 68 nm (arrow)

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8
Q

What type of fiber is shown in the image

A

Organization of type I collagen fibers

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9
Q

Collagen I fibers

A
  • Flexible with high tensile strength
  • The main structural collagen and is found in fibrous supporting tissue, skin (dermis), tendons, ligaments and bone.
  • When examined with the TEM, collagen fibers appear as bundles of fine, thread- like subunits, the collagen fibrils
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10
Q

Reticular Fibers (type III collagen)

A
  • Formstroma(delicate supporting network) around functional cells (parenchyma) of many organs such as endocrine glands, lymph nodes, bone marrow and liver.
  • StainpoorlywithH&Ebut stain with silver salts
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11
Q

What type of fiber is shown in the image

A

Reticular fibers (arrows, silver stain)

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12
Q

What is depicted in the image and what is the arow pointing to

A

Liver cirrhosis

arrow pointing to collagen build up

Example of fibrosis

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13
Q

Fibrosis

A

Fibrosis is defined by the overgrowth, hardening, and/or scarring of various tissues and is attributed to excess deposition of extracellular matrix components including collagen.

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14
Q

What does fibrosis result from

A

• Results from chronic inflammatory reactions induced by a variety of stimuli including persistent infections, autoimmune reactions, allergic responses, chemical insults, radiation, and tissue injury.

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15
Q

What is depicted in each image shown

A

Elastin fibers (arrows) are seen in the mesentery (a), dermis (b) and in the wall of aorta (c)

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16
Q

Elastic Fibers

A
  • They have rubber-like properties that allow tissues to stretch or bend and recoil
  • Present in large amounts in tissues such as lung, skin, urinary bladder and the wall of blood vessels
  • They are composite of fibrillin which forms a network of microfibrils, embedded in a larger mass of cross-linked elastin
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17
Q

What is shown in the image

A

Electron micrographs of Elastin fibers (E). Arrows show the fibrillin microfillaments

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18
Q

What is shown in the image

A

Fibroblasts (arrows)

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19
Q

What is shown in the image

A

Myofibroblasts (arrows)

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20
Q

Fibroblasts

A
  • Synthesize collagen, elastic and reticular fibers and the complex carbohydrates of the ground substance in the ECM.
  • During wound healing fibroblasts differentiate into myofibroblasts to repair the damaged organ
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21
Q

Permanent supporting (resident cells). They develop and remain in connective tissues

A

– Fibroblasts

– Adipocytes

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22
Q

Transient defense cells develop elsewhere, migrate into connective tissues for surveillance and in response to specific stimuli

A

– Macrophages

– Mast cells
– Plasma cells

– Leukocytes

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23
Q

Macrophages

A
  • Phagocytic cells
  • Blood-born cells that arise from monocytes
  • They have different names in different tissues, e.g. Kupffer cells in the liver, microglia in the CNS, alveolar macrophages in the lung.
24
Q

What is depicted in the image

A

M: acrophages

N: neurophils

BV: blood vessel

25
Q

What is the imagine showing

A

Electron micrograph of a macrophage

26
Q

Mast Cells

A
  • They arise from a pluripotential hemopoietic stem cell (HSC) in the bone marrow
  • After migrating into the connective tissue, immature mast cells differentiate and produce their characteristic granules
  • Granules contain: heparin, histamine, chemotactic factors and leukotrienes They release chemical mediators that promote allergic reactions and inflammation.
  • Absent from the CNS
27
Q

What are the arrows pointing to

A

Mast cell (arrows)

28
Q

What is depicted in the image

A

Electron micrograph of a mast cell

29
Q

Plasma cells

A
  • Plasma cells are antibody- producing cells derived from B lymphocytes
  • The Golgi apparatus is usually prominent because of its relatively large size and lack of staining.
  • The cytoplasm displays strong basophilia because of an extensive rER
  • The nucleus is spherical and typically offset or eccentrically positioned
30
Q

What type of cell is shown in this image

A

Plasma cell

31
Q

What type of cell is shown in this image

A

Plasma Cell

32
Q

Leukocytes

A
  • White blood cells that include lymphocytes (B lymphocytes, T lymphocytes) monocytes and granulocytes (neutrophils, eosinophils,basophils)
  • Transient cells that enter the connective tissue in response to specific stimuli
33
Q

What type of cell is depicted in the image

A

Leukocytes (neutrophils, arrows) normally found in the lamina propria of the small intestine

34
Q

Adipocytes

A
  • Specialize in storage
  • Found isolated or in groups within loose and dense irregular connective tissue
  • Predominate in the adipose tissue:

– Unilocular adipocytes: in white adipose tissue

– Multilocular adipocytes: in brown adipose tissue

35
Q

What type of cell is shown

A

Adipocyte

36
Q

What type of cell is shown

A

a. White adipose tissue b. Higher magnification. A: adipocyte

  • Unilocular: Found in white adipose tissue
  • Contain one huge lipid droplet
37
Q

What type of cell is shown

A

Adipocytes

  • Multilocular: Found in brown adipose tissue
  • Contain many small lipid droplets and numerous mitochondria
38
Q

Embryonic connective: Mesenchyme

A
  • Embryonic connective tissue that produces all types of connective tissue
  • Consists of mesenchymal cells that are:

– undifferentiated cells

– elongated cells with large nuclei

• ECM consists mostly of ground substance rich in hyaluronan (hyaluronic acid) and very little collagen

39
Q

What type of cell is shown

A

Mesechymal cells (arrows)

40
Q

Embryonic connective tissue: Mucous (or mucoid) connective tissue

A
  • Presentinumbilicalcord
  • Gelatinouswithfew fibroblasts and collagen fibers and abundant ground substance known as Wharton’s jelly
  • Manymesenchymalstem cells among fibroblasts
41
Q

What type of tissue and cells are depicted in the image

A

Embryonic connective tissue: Mucous (or mucoid) connective tissue

42
Q

Loose (areolar) connective tissue

A
  • Large amount of ground substance and less collagen
  • Contains numerous fibroblasts
  • Forms a layer beneath the epithelial lining of many organs
  • Fills spaces between muscle and nerve fibers
  • Flexible but not very resistant to stress
  • Well vascularized
  • Site of inflammatory and immune reactions
43
Q

What type of connective tissue is depicted

A

Loose (areolar) connective tissue

44
Q

Dense connective tissue

A
  • Fewer cells but many collagen fibers and less ground substance than loose connective tissue
  • It protects organs and strengthens them structurally
45
Q

What type of tissue is depicted

A

• Dense irregular connective tissue

– Fibers arranged in multiple directions

– Resistance to stress from all directions

46
Q

What type of tissue is depicted

A

• Dense regular connective tissue

– Collagen fibers and fibroblasts arranged in parallel

– Resistance to prolonged or repeated stress from the same direction

47
Q

Elastic connective tissue

A
  • Dense connective tissue rich in elastic fibers
  • Provides resistance to tissue allowing them to recoil after stretching
  • They stain poorly with H&E and require special staining (e.g orcein, fuchsin)
48
Q

What type of connective tissue is this

A

Elastic connective tissue

49
Q

What type of connective tissue is this

A

Elastic connective tissue

50
Q

Reticular connective tissue

A

Contains type III collagen (reticular) fibers produced by specialized fibrobasts (reticular cells)

  • They create a delicate scaffolding (stroma) for lymphoid organs (lymph nodes and spleen), bone marrow and liver
  • Reticular fibers are enveloped by reticular cells.
  • Contains transient cells (macrophages and dendritic cells)
51
Q

What is shown in the images below

A

a) Reticular fibers (arrows). b) Reticular fibers (arrows, silver staining)

52
Q

Adipose Tissue

A
  • Fat-storingcells (adipocytes) predominate
  • Typesofadiposetissue:

– White adipose tissue: contains mostly unilocular adipocytes mostly

– Brown adipose tissue: contains mostly multilocular adipocytes

53
Q

White Adipose Tissue

A
  • It typically forms 20% of the body weight in adults
  • Long-term energy storage
  • Provides thermal insulation for the body
  • Fills spaces between other tissues, helps keeps organ in place, acts as a cushion in regions subject to repeated mechanical stress (e.g. palms, heels)
  • Produces various hormones, growth factors and other important substances
54
Q

Brown Adipose Tissue

A
  • Constitutes 2%-5% of the newborn body
  • Serves for heat production, but not for energy storage
55
Q

What type of tissue is the arrow pointing to, be specific

A

Brown adipose tissue