Lecture 19 - Hair, Sweat And Nails Flashcards

1
Q

Hair

A

AKA pili
Flexible strands of dead, keratinized cells produced by hair follicles.
Made of hard keratin

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2
Q

Functions of hair

A

Warning of parasites on skin
Insulating against heat loss
Protecting head against physical trauma
Shielding skin from sunlight

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3
Q

Main regions of hair

A

Shaft - projecting from the skin
Root- embedded in the skin

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4
Q

Hair structure (3 layers)

A

Inner core - medulla (not all hairs have medulla)
Middle layer - cortex
Outer layer - cuticle

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5
Q

Hair pigment

A

Melanins of different colours
Made by melanocytes at the base of the hair follicle and transferred to the cortical cells. Combinations of different melanins create all the hair colours

Red hair- additional pheomelanin in pigment
Gray/white- melanin production decreases and air huddles replace melanin

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6
Q

Structure of hair follicle

A

Hair follicles fold down from the epidermis into the dermis and occasionally into the hypodermis

Deep end of hair follicle is expanded forming a hair bulb, surrounded by sensory nerve endings called hair follicle receptor

Wall composed of dermal sheath, thicker basement membrane from the dermis and inner epithelial root sheath derived from the epidermis

Hair matrix, within hair bulb is a group of actively dividing cells that produce the hair.

Arrector pili muscle, when contraction occurs, hair stands upright

Hair papilla, dermal tissue containing knot of capillaries that’s up lies nutrients to growing hair

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7
Q

Types and growth of hair

A

Pale,fine vellum hairs

Long,coarse terminal hairs

Rate of hair growth varies, influence by factors such as nutrition and hormones

Grow in cycles, grow continuously for 2-7 years, then slow down for 2-3 weeks and rest for 2-4 months before growing begins again

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8
Q

Hair thinning and baldness

A

Follicles have limited number of cycles, and after age 40, hair is not replaced as quickly as it is lost, which leads to hair thinning and some degree of balding, or alopecia, in all humans

True baldness, such as male pattern baldness, is a genetically determined, sex influenced condition caused by a gene that changes the hair follicle in response to the hormone dihydrotestosterone

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9
Q

Factors that induce hair thinning

A

Acutely high fever
Surgery
Sever emotional trauma
Certain drugs ( such as antidepressants etc)
Protein deficient diets
Alopecia areata: immune system attacks follicles

Some hair loss is reversible, but others (burns or radiation) are permanent

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10
Q

Sebaceous (oil) glands

A

Secrete sebum, oily secretion, found all over the body except palms of hands and soles of feet

Function as holocrine glands, secreting their product into hair follicle or to a pore on the surface of the skin

Softens and lubricates hair and skin, slows water loss and is bactericidal

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11
Q

Eccrine sweat glands (merocrine)

A

Produce true sweat and are abundant on the palms of hands and soles of feet and forehead

Ducts connected to pores

Secretion of eccrine glands regulated by sympathetic nervous system and used to prevent the body from overheating

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12
Q

Apocrine sweat glands

A

Confined to axillary (armpit) and anogenital areas

Produce fat and protein rich true sweat
Larger than eccrine sweat glands and have ducts emptying into hair follicles
Begin functioning at puberty

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13
Q

Modified sweat glands

A

Ceruminous glands - modified appocrine sweat glands found in lining of the ear canal, secrete earwax aka cerumen

Mammary glands- modified apocrine sweat glands that secret milk

These glands do not produce true sweat

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14
Q

nails

A

Scale like modification of the epidermis, forms protective covering on the dorsal side of the distal finger or toe

Made of hard keratin, have free edge, nail body attached to skin, and root embedded in the skin

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15
Q

Nail matrix

A

located proximal part of nail bed, epithelium responsible for nail growth, contains dividing cells, which produce new nail cells

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16
Q

Free edge

A

Extends past finger or toe

17
Q

Proximal nail fold and lateral nail folds

A

Where skin covers over the edges of the nail

18
Q

Lunula (“little moon”)

A

The thick, white part of the nail (bottom of nail)

19
Q

Eponychium (cuticle)

A

Stratum corneum of the epidermis at the proximal nail fold

20
Q

Nail root

A

Portion that is not visible

21
Q

Nail body

A

Visible portion of the nail

22
Q

Hyponychium

A

Secures nail to fingertip

23
Q

Distal phalanx

A

Finger or toe bone under the nail