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Anatomy > The Hair > Flashcards

The Hair Flashcards

1
Q

What is trichology?

A

Trichology is the study of hair.

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2
Q

What is hair and what is it composed of?

A

Hair is an appendage of the skin and it is chiefly composed of the protein keratin.

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3
Q

What areas on the body don’t have hair?

A

Hair is everywhere except the soles of feet, the palms of hands, some areas of the genitals (sex organs), mucous membranes of lips, nipples (areola not included) and the navel.

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4
Q

What areas of the body have the heaviest concentrations of hair?

A

The scalp, axillary region, on the arms, legs, and on and around the genitals are areas with the heaviest concentration of hair.

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5
Q

What is hair important for?

A

Hair has important functions in social functioning.

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6
Q

What do hair follicles do?

A

A hair follicle anchors each hair to the skin.

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7
Q

What forms the base of a hair follicle?

A

A hair bulb forms the base of the hair follicle.

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8
Q

What do living cells do in the hair bulb and how are blood vessels important for hair growth?

A

In the hair bulb, living cells divide and grow to build the hair shaft. Blood vessels nourish the cells in the hair bulb, and deliver hormones that modify hair growth and structure at different times of life.

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9
Q

What are the 3 phases of hair growth?

A

Anagen, Catagen, and Telogen.

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10
Q

What is the anagen phase of hair growth?

A

The anagen phase of hair growth is the growth phase of hair growth. Most hair is growing at any given time. Each hair spends several years in this phase.

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11
Q

What is the catagen phase of hair growth?

A

The catagen phase of hair growth is the transitional phase of hair growth. Over a few weeks, hair growth slows and the hair follicle shrinks during the catagen phase.

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12
Q

What is the telogen phase of hair growth?

A

The telogen phase of hair growth is the resting phase. In the telogen phase over months, hair growth stops and the old hair detaches from the hair follicle. A new hair begins the growth phase (anagen), pushing the old hair out.

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13
Q

How quickly does hair grow?

A

Hair grows at different rates in different people; the average rate is around one-half inch per month.

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14
Q

How is hair colour created and what happens as we age?

A

Hair colour is created by pigment cells producing melanin in the hair follicle. With aging, pigment cells die, and hair turns grey.

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15
Q

What is alopecia areata?

A

Alopecia areata is round patches of total hair loss, usually from the scalp. The cause of alopecia is unknown; the hair usually grows back.

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16
Q

What is male pattern baldness?

A

Male pattern baldness is the most common type of hair loss in men. Male pattern baldness usually includes either a receding hairline, hair loss at the crown or both.

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17
Q

What is female pattern baldness?

A

In women, hair loss usually includes uniform thinning across the scalp, with a preserved hair line. The crown may be affected, but hair loss rarely proceeds to baldness as in men.

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18
Q

What is dandruff? (seborrheic dermatitis)

A

Dandruff is ongoing, mild inflammation of the scalp, resulting in scaly skin that may be itchy and flake off. Seborrheic dermatitis may also affect the ears and face.

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19
Q

What is tinea capitis? (ringworm)

A

Tinea capitis or ringworm is a fungal infection of the scalp, creating round patches of hair loss. Although the patches can appear in a ring shape, no worm is involved in tinea capitis.

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20
Q

What is trichotillamania?

A

Trichotillamania is a mental disorder that includes the irresistible urge to pull out one’s hair. The hair pulling results in patches of noticeable hair loss; its cause is unknown.

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21
Q

What is head lice?

A

Head lice are tiny insects that live on the scalp and feed on blood. Preschool and elementary school-aged children and adults who live with children are most susceptible to catching head lice, which are only spread through close contact.

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22
Q

What is telogen effluvium?

A

Telogen effluvium occurs a month or two after a personal shock (such as surgery, childbirth, or severe stress), hair can abruptly fall out in large patches. Typically new hair starts regrowing right away.

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23
Q

What is postpartum alopecia?

A

Postpartum alopecia is hair loss that occurs after delivering a baby - it is a form of telogen effluvium and usually resolves without treatment.

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24
Q

What is folliculitis?

A

Folliculitis is inflammation of hair follicles, usually due to an infection. Usually a bacterial infection. Acne is a form of folliculitis caused by inflammation.

25
Q

What is piedra? (Trichomycosis nodularis)

A

Piedra is a fungal infection of the hair shaft. Hard nodules made of fungus cling to hair fibres, sometimes causing hair loss.

26
Q

What is hirsutism?

A

Hirsutism is a condition in which women develop male-pattern hair (such as facial hair). An excess of testosterone due to a medical condition is usually responsible.

27
Q

What do hair follicles contain and what can this be tested/used for?

A

Hair follicles contain DNA; hair can be tested to establish paternity or as evidence in a crime investigation.

28
Q

What are the functions of hair?

A

Protection and sensory reception.

29
Q

How does the hair offer protection?

A

Hair has comparatively little protective value in people. However eyelashes, and eyebrows, hairs inside external ears and nostrils, and those around anogenital orificies have useful functions - prevention of entry of germs. When scalp hair is thick and long, it provides some protection from the elements (heat regulation).

30
Q

How does hair assist in sensory reception?

A

All hair follicles are surrounded by sensory nerves, which respond to pressure on the shaft. All human hair follicles, (especially those on the face and anogenital areas,) are well supplied with nerves.

31
Q

What factors influence hair growth?

A

Race, heredity, age, sex, body region, season of year, hormones, nutrition, medication (chemotherapy, steroids), illness, stress level.

32
Q

What is the hair shaft?

A

The hair shaft is the part of the hair above the scalp or skin - emerging from the follicle out of a follicular pore.

33
Q

What does the hair shaft consist of? (histology of hair shaft)

A
  1. Outer cuticle
  2. A central medulla
  3. A cortex between the two
34
Q

What is the cuticle (hair) and what is its function?

A

The cuticle is the outer layer of hair. It is a single layer of overlapping scales and is translucent. Cuticle scales are interlocked with those of the inner root sheath, which anchors the hair in the follicle.

The cuticle holds the cortex together and gives the hair its elasticity.

35
Q

What is the cortex?

A

The cortex is next to the cuticle layer of hair lying closer to the centre of the shaft. Melanin granules are found in this layer, which gives hair its colour. When melanin is absent, hair appears dull, white or translucent. The cortex is made up of more than one layer of keratinized cells.

36
Q

What is the medulla?

A

The medulla is the centre of the hair shaft. It is composed of large, loosely connected horny cells. It may be absent, as in very fine hairs.

37
Q

How many sebaceous glands are attached to each hair and what do they do in relation to hair?

A

Two or more sebaceous glands are attached to each hair. Sebaceous glands drain into every hair follicle, coating hair with sebum, an oil fatty substance.

38
Q

What are the functions of sebum?

A

Lubricates hair, protects hair, keeps hair soft and pliant, keeps scalp soft and supple, prevents excess absorption through skin, prevents excess evaporation through skin, lessens heat loss/fat poor conductor, maintains acid mantle of skin pH.

39
Q

What does the hair follicle consist of?

A

The outer root sheath and the inner root sheath.

40
Q

What is the outer root sheath?

A

The outer root sheath lies farthest from the hair shaft. A bulge in the outer root sheath at the insertion of arrestor pili muscles, houses several types of stem cells, which supply the hair follicle with new cells.

41
Q

What is the germinal matrix of hair?

A

Germinal - in the first stages of growth or development matrix.

The matrix is the living and reproducing part of the hair and nails.

42
Q

What is hair papilla?

A

The hair papilla is a small cone shaped elevation, at the bottom of the hair follicle which houses the blood supply which nourishes the hair matrix.

43
Q

What feeds the cells in the hair papilla and why?

A

Nutrients from the digestive system and O2 from the respiratory system feed the cells for growth and development.

44
Q

What determines pattern of hair growth?

A

Hormones from the endocrine system determine the pattern of hair growth.

45
Q

What is the hair root and what does it contain?

A

The hair root is the part of the hair below the skin. It contains the matrix.

46
Q

What kind of reproduction happens with the cells in the hair matrix?

A

The cells within the matrix reproduce new cells by mitosis.

47
Q

What is the hair bulb?

A

The hair bulb is the inferior and swollen part of the root; base of hair follicle where new hair develops.

48
Q

What are arrestor pili?

A

Arrestor pili are the minute involuntary muscle fibres in the skin attached to the bases of hair follicles; cold or fright causes contraction which pulls hair bolt upright and creates goosebumps.

49
Q

What are nerve endings in relation to hair?

A

Nerve endings are a collar of sensory nerve endings from a single nerve, encircles the follicle, about 1/2 way between base of follicle and skin surface. Nerve endings signal brain if hair is touched.

50
Q

When do hair follicles form? How do they form?

A

Many months before birth hair follicles begin to develop in most parts of the skin. Cells of the epidermis grow down into the dermis, forming a small tube, the follicle. The stratum germinativum develops into the follicles inner most layer and forms at the bottom of the follicle a cap shaped cluster of cells known as germinal matrix.

51
Q

What protrudes into the germinal matrix?

A

Protruding into the germinal matrix, is a small mound of the dermis called the hair papilla a very important structure since it contains blood capillaries that nourish the germinal matrix.

52
Q

What do cells in the germinal matrix do and how is hair formed?

A

Cells of the germinal matrix are responsible for forming hairs, and reproduce rapidly and die. They undergo mitosis repeatedly, push upwards in follicle and become keratinized to form hair. As long as cells of germinal matrix remain alive, hair will regenerate, even when it is cut or tweezed or otherwise removed.

53
Q

How much hair grows in a year on average?

A

The average hair grows a little less that 1/2 an inch per month, or 5 inches per year. However, body hair grows more slowly.

54
Q

What three changes in a women’s life can effect hair growth?

A

Puberty, pregnancy and menopause.

55
Q

How does puberty effect hair growth?

A

Puberty changes hair growth in teenagers.

56
Q

How can pregnancy change hair growth?

A

Pregnancy can activate hair growth making it thicker in certain areas of the body.

57
Q

How does menopause effect hair growth?

A

Menopause can activate male characteristic hair growth in women.

58
Q

What does the colour of hair depend on?

A

The colour of hair depends on melanin, dark pigment made by melanocytes and deposited in some growing hairs. Most hair pigment is in the cortex. If pigment has disappeared, hair looks grey or white. The amount of melanin is genetically determined.

59
Q

How is red hair produced?

A

Red hair is the product of a separate gene. This gene produces red pigment that adds to another colour in a persons hair. True redheads possess only special red pigment.

Anatomy (15 decks)

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