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ESA1 Callum's cards > TOB S5 - Connective Tissues and Skin > Flashcards

TOB S5 - Connective Tissues and Skin Flashcards

1
Q

What is the embryonic origin of connective tissues?

A

Mesoderm

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2
Q

What are the three basic components of connective tissue?

A

Cells
Extracellular fibres
Amorphous ground substance

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3
Q

What are the basic functions of connective tissues?

A

Supporting organs
Filling spaces between organs
Forming tendons and ligaments

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4
Q

What are the Resident cell types in connective tissues?

A

Fibroblasts/cytes
Mesenchymal cells
Macrophages aka. Tissue histocytes

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5
Q

What are the Visitant cell types in connective tissues?

A

Mast cells
Plasma cells
Adipocytes
Leukocytes

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6
Q

What is the function of fibroblasts/cytes in connective tissues?

A

Synthesise and maintain extracellular matrix (Including collagen, elastic fibres, reticular fibres and ground substance)

Fibrocytes are more mature and less active fibroblasts.

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7
Q

What is the function of Mesenchymal cells in connective tissues?

A

Undifferentiated cells that differentiate into other cells and maintain extracellualar materials

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8
Q

What is the function of macrophages in connective tissues?

A

Ingest foreign material (bacteria, dead cells, cell debris)

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9
Q

What type of cells are macrophages derived from?

A

Monocytes

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10
Q

Give the specific names of monocytes found in:

The Liver
The CNS
Bone

A

Liver - Kupfer cells
CNS - Microglia
Bone - Osteoclasts

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11
Q

What is the function of mast cells in connective tissues?

Give 2 examples of molecules found in these cells.

A

Congregate near blood vessels and release pharmacologically active molecules

Eg Heparin, Histamine found in granules in the cell

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12
Q

What is the function of adipocytes in connective tissues?

A

Found in small clusters or aggregates, they store lipids and act as a insulator and shock absorber (cushioning organs and joints).

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13
Q

What is the function and derivation of leukocytes in connective tissues?

A

Derived from blood cells, responsible for production of immunocompetent cells

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14
Q

How does composition of connective tissue determine function?

A

The constituents of the extracellular matrix define whether the tissue is a loose packing tissue or of primary mechanical importance

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15
Q

What are the three fibres found in connective tissue’s extracellular matrix?

A

Collagen
Reticular
Elastic

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16
Q

In what form does collagen occur in connective tissues?

Where does collagen synthesis occur?

A

Occurs in bundles of non-elastic fibres of variable thickness

RER of cells

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17
Q

What is the most common type of collagen?

A

Type 1

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18
Q

Describe the composition and form of Reticular fibres

A

Made up of type three collagen.

Forms thin branching fibres that form delicate networks around certain structures

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19
Q

Around what structures might a network of reticular fibres be found?

A

Blood vessels, adipocytes, smooth muscle cells, nerve fibres, certain epithelial cells

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20
Q

Around what organs do reticular fibres form a structural framework/supporting mesh?

A

Liver
Spleen
Bone Marrow
Lymphoid organs

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21
Q

Describe the structure and function of Elastic fibres

A

Highly elastic fibres containing amorphous protein and elastin surrounded by fibrillin

Can stretch up to 150% restin length due to high lysine content

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22
Q

Describe the structure and function of the amorphous ground substance in connective tissue

A

Gel like matrix in which fibres and cells are imbedded. Tissue fluid diffuses through it.

Composed of Glycosaminoglycans (GAGs), Proteoglycans and glycoproteins.

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23
Q

Where is loose connective tissue found in organs?

A

Forms the septa (walls) and trabeculae (rods) that make up the framework inside organs

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24
Q

How might loose connective tissue become distended?

A

During Oedema distended by Extracellular fluid (ECF)

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25
Q

Describe the composition of mucous connective tissue (Wharton’s Jelly)
Where it might be found?

A

Large stellate fibroblasts (that will often fuse with similar adjacent cells)

Few macrophages and lymphocytes present

Ground substance has high concentration of Hyaluronic acid and a network of fine collagen fibres

Only found in Umbilical cord and Subdermal connective tissue of the embryo

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26
Q

Where might Areolar connective tissue be found?

A 
Deep under the skin
Submucosa
Below mesothelium of peritoneum
Associated with adventitia of blood vessels
Surrounding parenchyma of glands
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27
Q

In terms of loose connective tisse what are the distinguishing features of areolar connective tissue

A

Contains fibroblasts and macrophages as well as some mast cells

Collagen fibres abundant but elastin fibres also present.

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28
Q

In terms of Loose connective tissue what is unique about the structure of Adipose tissue?

A

Loose connective tissue with adipocytes occuring singularly or in groups between collagen fibres

Adipocytes make up the majority of cells

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29
Q

What are the 4 common types of Loose connective tissue?

A

Areolar
Adipose tissue
Reticular tissue
Mucous connective tissue

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30
Q

How does the structure of Dense connective tissue vary from loose connective tissue?

A

Closely packed fibres
Fewer cells
Less ground substance

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31
Q

What is the defining feature of dense regular connective tissue and how does this relate to function?

Where is dense regular CT found?

A

Fibres oriented in parallel to provide maximum tensile strength

Tendons, Aponeuroses (flattened tendons) and Ligaments

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32
Q

How does fibre arrangement in ligaments differ from tendons?

A

Collagen fibres in ligaments less regularly arranged

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33
Q

In what types of Dense regular connective tissue can fibroblasts be found?

A

All of them

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34
Q

What is an elastic ligament?

A

A ligament where most fibres are elastin

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35
Q

What is a fascicle in a tendon?

A

A bundle of collagen and fibroblasts

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36
Q

Where does Loose connective tissue occur in tendons?

A

Endotendineum (layers of LCT interspersed through collagen)

Peritendineum (outer layer of LCT around tendon)

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37
Q

What surrounds tendons?

A

A fibrous sheath

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38
Q

Describe the structure of Dense irregular connective tissue and relate this to function

A

Collagen fibres criss cross in many directions to counteract multidirectional forces to which the tissue is subjected.

Mostly collagen with some elastic and reticular fibres

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39
Q

Where might Dense irregular connective tissue be found?

A 
Deep fascia of muscles
Dermis of skin
Periosteum
Perichondruim
Dura matter
Capsules, large septa and trabeculae of many organs
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40
Q

What causes Systemic Sclerosis and what does it cause?

A

Excessive accumulation of collagen (fibrosis) in all organs

Causes hardening and functional impairment

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41
Q

What is a keloid scar and why do they form?

A

Scars on the skin caused by abnormal amounts of collagen

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42
Q

What is the result of vitamin C deficiency?

A

Defective collagen synthesis leading to degeneration of connective tissue.

Peridontal ligament is highly affected due to high collagen turnover

Loosening of teeth in their sockets with subsequent loss.

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43
Q

What causes Marfan’s syndrome and what is a major effect of this?

A

Genetic defect in gene coding for fibrillin leading to undeveloped elastic fibres.

Large elastic arteries (eg. Aorta) can rupture due to weakened connective tissue.

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44
Q

What is the result of Ethlers-Danos disease?

A

Deficiency of type 3 collagen causing ruptures in tissue with high reticulin content.

45
Q

What macroscopic features of skin are subject to variation?

A 
Colour
Hair
Thickness
Laxity/Wrinkling
Oiliness
46
Q

What reasons are behind variations in skin colour?

A

Ethnicity
UV exposure
Site (lips/areolar)

47
Q

What reasons are behind variation in skin hair?

A

Site (Armpit vs Palm)
Sex (Facial and more profuse body hair in men)
Age (baldness in men, greying in both sexes)
Ethnicity (colour, character)

48
Q

What are the reason/s behind variation in skin thickness?

A

Site (scalp vs ball of foot)

49
Q

What factors affect skin laxity/wrinkling?

A

UV exposure
Site
Age

50
Q

What factors might affect skin oiliness?

A

Puberty

Site

51
Q

How does variation in skin colour influence presentation of vitiligo?

A

Much less of a problem in fair skinned as it is barely visible.

52
Q

How does variation in skin colour influence susceptibility to skin damage or skin cancer?

A

Fair skinned more susceptible to:

UV induced acute sunburn
Freckling
Ageing
Skin cancer

53
Q

What is the type of cell found in the epidermis?

A

Stratified squamous keratinised epithelium made up mainly of keratinocytes

54
Q

What are the four layers of the epidermis?

Give in descending order.

A 
Horny layer(stratum corneum)
Granular layer(stratum granulosum)
Prickle cell layer(stratum spinosum)
Basal layer(stratum basale)
55
Q

Describe the processes of keratinocyte mitosis and differentiation

A

Keratinocytes from the stratum basale move upwards after undergoing mitotic division to form the stratum spinosum, where terminal differentiation begins

They then lose their ability to divide

56
Q

What do keratinocytes produce?

A

Synthesise Keratins

57
Q

What are the functions of keratins in the skin?

A

Contribute to strength of epidermis

Main constituent to hairs and nails

58
Q

Describe the molecular structure of keratins.

A

Heterodimeric fibrous proteins

59
Q

What changes to keratinocytes occur as they move into the granular layer?

A

Lose their plasma membrane

Begin differentiating into corneocytes (main cells of the stratum corneum)

60
Q

Apart from cells, what is another component of the stratum granulosum?

A

Keratohyalin granules

61
Q

What is the composition of keratohyalin granules?

A

Keratins

Other fibrous proteins (eg Filaggrin, involucrin)

Enzymes which degrade the phospholipid bilayer of cells
E.g. Phospholipases

Crosslink proteins (eg Filaggrin, involucrin)

62
Q

What are the functions of filaggrin and involucrin?

A

Filaggrin: Aggregates keratins

Involucrin: Forms a major part of corneocyte envelope

63
Q

What type do cells make up the stratum corneum?

What is the function of the stratum corneum?

A

Made up of layers of flattened corneocytes

Major function is as a barrier (resists abrasion etc)

64
Q

What is the transit time from stratum basale to stratum corneum for a cell?

A

30-40 days

65
Q

What are melanocytes, what is their embryonic origin and where are they found?

A

Dendritic cells of neural crest origin

Stratum basale

66
Q

What is the function of melanocytes?

How does ethnicity effect their function?

A

Produce melanin

Produces more melanin in darker skin

67
Q

What are Langerhans cells and where are they found?

A

Dendritic cells of bone marrow origin

Scattered throughout stratum spinosum

68
Q

What is the function of Langerhans cells?

A

Present antibodies to T lymphocytes

Mediate immune reactions (Eg allergic contact dermatitis)

69
Q

What is significant about the staining properties of melanocytes and Langerhans cells?

A

Difficult to see without special stains

70
Q

Where is the dermo-epidermal junction and what does it consist of?

A

Just below the stratum basale

Basement membrane

71
Q

What stain is used to best see the dermo-epidermal junction?

A

PAS

72
Q

What are the constituents of the Dermis layer of skin?

A 
Fibroblasts and extracellular matrix
Blood vessels
Lymph vessels
Mast cells
Nerves
73
Q

What is the function of fibroblasts in the dermis?

A

Synthesise the extracellular matrix

74
Q

What does the extracellular matrix of the dermis contain?

A

Collagens (especially type 1)
Elastin
Other extracellular matrix components

75
Q

What is the main component of scar tissue?

A

Collagen

76
Q

What is the result of excessive scar tissue production following wounding?

A

Keloids

77
Q

Describe the form and distribution of blood vessels in the dermis?

A

Small blood vessels in the more superficial dermis
(Mainly capillaries, some small venules and arterioles)
Larger blood vessels in the deeper dermis

78
Q

How do birthmarks arise?

A

Congenital malformation of dermis blood vessels

79
Q

Where are mast cells found in the dermis?

A

Distributed around blood vessels

80
Q

What is the major significant secretory product of mast cells in the dermis?

A

Histamine

81
Q

What is the result of histamine release from mast cells in the dermis?

A

Increased vascular permeability leading to plasma leakage into dermis.

This results in localised oedema that causes urticaria (hives) and angio-oedema in the skin.

82
Q

What is the function of nerves in the dermis?

A

Sensory nerves transmit sensation

83
Q

Name the various skin appendages found in the dermis

A

Hair follicles and sebaceous glands (Pilosebaceous unit)
Sweat glands
Nails
Immediate subcutaneous fat (adipose tissue)

84
Q

What type of glands are sebaceous glands and what type of secretion do they utilise?

A

Branched acinar

Holocrine secretion

85
Q

What is the clinical significance of the sebaceous duct in a Pilosebaceous unit?

A

Acne obstructs flow of secretions through this duct onto hair

86
Q

What are the two types of sweat glands?

A

Eccrine (merocrine)

Apocrine

87
Q

What is the function of Eccrine sweat glands?

Where are they found?

How are they controlled?

A

Major sweat glands found in most areas of the body

Produce a clear, odourless secretion of water and NaCl (NaCl reabsorbed in duct to reduce salt loss)

Active in thermoregulation

Controlled by the hypothalamus

88
Q

Describe the composition of an Eccrine sweat gland

A

Intra-epidermal spiral duct
Straight dermal portion of duct
Coiled acinar secretory portion in the dermis

89
Q

Where are Apocrine sweat glands most abundant?

A

Axillae
Genitals
Submammary area

90
Q

What is the function of Apocrine sweat glands?

A

Produce odourless, protein rich secretions

This function is of no discernible value

91
Q

How is body odour produced?

A

Digestion of protein rich secretions from Apocrine sweat glands by cutaneous microbes

92
Q

What are the main functions of the skin?

A

Barrier
Sensation
Thermoregulation
Pychosexual communication

93
Q

Describe the barrier function of the skin.
How is this relevant to drug administration?

Give an example of a disease that might disrupt the barrier function.

A

Stratum corneum forms a major barrier preventing percutaneous absorption of exogenous substrates

The barrier must be overcome during percutaneous absorption of drugs

Barrier may be seriously disrupted by Psoriasis.

94
Q

Describe the Sensory function of the skin.

A

Sensory nerves of the skin allow a sense of:

Temperature
Touch
Tissue damage (Pain)

95
Q

Give two examples of diseases that affect the sensory function of the skin.

A

Leprosy - Disease of the peripheral nerves

Diabetic sensory neuropathy

96
Q

What are the two methods of thermoregulation employed by the skin

A

Vascular thermoregulation

Thermoregulatory eccrine sweating

97
Q

What are the twin processes involved in vascular thermoregulation and the consequences of each?

A

Dilation of skin blood vessels:
Leads to heat loss

Constriction:
Leads to pallor and heat conservation

98
Q

How is eccrine sweating involved in thermoregulation?

A

Evaporation of eccrine sweat leads to cooling

99
Q

How is the skin involved in psychosexual communication?

A

Appearance manipulated as a means of communication or expression (Eg Tattoos and piercings)

100
Q

Describe the how Psoriasis leads to it’s characteristic scaled appearance

A

Extreme proliferation of stratum basale cells Causing gross thickening of Stratum spinosum and excessive stratum corneum production

Hence leading to the characteristic excess scaling of the skin

101
Q

What proportion of the population experiences Psoriasis in their lives?

A

2%

102
Q

What is the cause of Psoriasis?

A

Exact cause not known

However, it runs in families and so is influenced by genetic factors.

103
Q

What cells are associated with a malignant melanoma?

A

Tumour of melanocytes

104
Q

How is the dermo-epidermal junction significant to maligant melanoma prognosis?

A

Superficial spreading melanoma doesn’t penetrate the basement membrane and is associated with a good prognosis

More penetrating ‘nodular’ melanomas are associated with a very poor prognosis

105
Q

What makes malignant melanomas hard to spot in a clinical environment?

A

The look like moles (benign growths of melanocytes)

106
Q

What is Alopecia areata?

A

An autoimmune attack on hair follicles causing hair loss

107
Q

What is Vitiligo?

A

An autoimmune disease in which the immune system attacks melanocytes causing areas of de-pigmentation

108
Q

What is significant about the distribution of Vitiligo?

A

Usually occurs in symmetrical, localised areas

No known cause for this, possibly under neural control as melanocytes are derived from the neural crest

ESA1 Callum's cards (34 decks)

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