Tissue and Structures Flashcards

1
Q

What tissues is the body made up of?

A
  1. Epithelium.
  2. Connective tissue.
  3. Muscle.
  4. Nerve.
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2
Q

What elements (tissue) is skin made up of?

A
  1. Epithelium.
  2. Connective tissue.
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3
Q

What is the epithelium of skin called?

A

Epidermis.

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4
Q

What type of epithelium is the epidermis?

A

Stratified squamous keratin (variety).

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5
Q

What are the specialised derivatives of the epidermis?

A
  1. Sebaceous glands.
  2. Sweat glands.
  3. Nails.
  4. Hair.
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6
Q

What tissue is the dermis made of?

A

Connective tissue.

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7
Q

What is the origin of the dermis?

A

Mesodermal (in origin).

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8
Q

What does the dermis consist of?

A
  1. Collagen fibres (mainly).
  2. Elastic tissue.
  3. Blood vessels.
  4. Lymphatics.
  5. Nerve fibres.
    (All embedded in ground substance).
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9
Q

What is the uppermost layer of the epidermis called?

A

Stratum corneum.

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10
Q

What is the stratum corneum also known as?

A

It’s the cornified or horny layer.

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11
Q

What does the horny layer consist of?

A

Dead cells (keratin) - these have lost their nuclei. Empty husk.

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12
Q

What happens with the dead cells of the epidermis?

A

The keratin are constantly being rubbed off and replaced by the cells moving up from the deeper layers.

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13
Q

How is dandruff formed?

A

Scaly flakes of the horny layer are trapped by the hairs instead of falling out.

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14
Q

How is the horny layer softened?

A

Greasy secretions of sebaceous glands.

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15
Q

How is the horny layer moistened?

A

Watery secretions of sweat glands.

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16
Q

What’s the importance of keratin having a husk and being linked up and thick?

A

It is so that it is impermeable to water.

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17
Q

What happens to keratin when there is prolonged exposure to water?

A

Keratin is macerated by the water, so it becomes thick, soft and white.

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18
Q

Define thick skin?

A

Increased thickness of cornified layer of epidermis.

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19
Q

Where do you find thick skin?

A

Sole of feet.

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20
Q

In thick skin what happens to the dermis?

A

It is thin.

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21
Q

Define thin skin?

A

Decreased thickness of cornified layer.

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22
Q

In thin skin what happens to the dermis?

A

It is thick.

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23
Q

What is the main factor that determines the colour of our skin?

A

The degree of pigmentation produced by melanocytes.

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24
Q

Where are melanocytes found?

A

Basal layer of epidermis.

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25
Q

What do melanocytes produce?

A

Melanin granules.

26
Q

How do melanocytes produce melanin?

A

Melanocytes make melanin granules, these granules are liberated from the melanocytes, and are ingested by other epidermal cells.

27
Q

How do you distinguish between cells that make melanin and those that have engulfed them?

A

Dopa reaction - DihydrOxyPhenylAlanine is converted by tyrosinase (enzyme) into melanin. The melanocytes have this occur in them.

28
Q

What is the difference between light skin and dark skin (in terms of melanocytes)?

A
  1. Both light and dark have the same number of melanocytes.
  2. Dark skin melanocytes are more active and produce more pigment.
29
Q

What can the sun do to light skin?

A

The sun can activate melanocytes in light skin (ultraviolet), this can cause the skin to become tanned. However, it can also induce cancerous changes, especially in those with fair skins.

30
Q

What is the purpose of dermis (skin) being bound firmly to the underlying aponeurosis in the palm and the sole?

A

To improve grip of the hand and foot.

31
Q

What are the creases in the skin?

A

Flexure lines over joints.

32
Q

What way does the skin fold?

A

Always in the same place.

33
Q

What is the thickness of the flexure lines?

A

Thin.

34
Q

How is the skin bound to the underlying structures?

A

Bound more firmly - classically to deep fascia.

35
Q

How many sweat glands does the skin contain?

A

3 million.

36
Q

Where are the sweat glands distributed?

A

All over the skin except on the following:
1. Margins of lips.
2. Glans penis.
3. Tympanic membranes.

37
Q

Where is the highest concentration of glands?

A

Thick skin of the palms and soles and on the face (including forehead).

38
Q

Describe the histology of sweat glands?

A

Coiled test-tubes that extend below the dermis into the subcutaneous tissue. The ducts are straight when going through the dermis but become corkscrew-like when going through epidermis.

39
Q

What are the type of sweat glands?

A
  1. Eccrine (majority).
  2. Apocrine.
    (The mode in secretion is the same in both).
40
Q

What is the purpose of eccrine glands?

A

Deliver water to the body surface to assist in temperature regulation. Also it’s an emotional response when activated on forehead, palms, soles.

41
Q

Where are the apocrine glands?

A
  1. Axillae.
  2. Areolae of breasts.
  3. Urogenital regions.
  4. Breasts themselves are modified apocrine glands.
42
Q

Which is larger apocrine or eccrine?

A

Apocrine.

43
Q

What is the function of apocrine glands?

A

Scent glands - help for recognition in breeding season.

44
Q

Where do the ducts of the apocrine glands open?

A

Into hair follicles.

45
Q

Is the apocrine secretion odourless?

A

Yes.

46
Q

When do apocrine glands become active?

A

In puberty - due to hormones.

47
Q

Where are sebaceous glands confined to?

A

Skin with hair.

48
Q

Where do sebaceous glands open?

A

Short duct into the side of a hair follicle.

49
Q

What sites do sebaceous glands open?

A
  1. Eyelids.
  2. Lips.
  3. Papillae of breasts.
  4. Labia minora.
    (none on palms or soles).
50
Q

What is hair?

A

Soft keratin.

51
Q

What happens with hair follicles after birth?

A

There is no new development of hair follicles.

52
Q

Where is each hair formed?

A

From the hair matrix - region of epidermal cells at base of hair follicle.

53
Q

How does hair grow?

A

The cells move up inside the tubular epidermal sheath of the follicle, lose their nuclei, and are converted into the hard keratin rod that is hair.

54
Q

How do people get hair colour?

A

Melanocytes in hair matrix impart pigment to the hair cells.

55
Q

Describe the growth period of hair?

A

Hair grows in periods at different sites with a growing phase of 2-3 years, then there is a rest phase for a few months.

56
Q

What happens in the rest phase of hair?

A

Hair falls out form the follicle - this is before the matrix creates new hair.

57
Q

Why does the hair not all fall out together at once?

A

Because the phases occur in different spots next to each i.e. growth next to rest phase. To make i not obvious.

58
Q

What is the growing phase for eyebrows?

A

1-2 months. Longer rest phase.

59
Q

Describe nails?

A

Nails are formed from a nail matrix - similar epidermal specialisation to hair matrices.

60
Q

What is the rule of nines?

A

Related to burns - size of the body parts in proportion to whole:
1. Head - 9%.
2. Upper limb - 9%.
3. Lower limb - 18%.
4. Front of thorax and abdomen - 18%.
5. Back - 18%.

61
Q

What are tension lines?

A

Lines that of the skin that display the pattern of fibre bundles in the dermis.

62
Q

What do crease lines run parallel with?

A

Tension lines.