Case 8 SBA

Question 1

What are the layers of the skin?

Answer 1

Cutaneous membrane and subcutaneous layer

Question 2

Accessory structures of the skin

Answer 2

Nails, exocrine glands, hair

Question 3

Layers of epidermis from deep to superficial

Answer 3

basale, spinosum, granulosum, lucidum (thick only), corneum

Question 4

Surface epithelium of epidermis

Answer 4

Keratinised stratified squamous

Question 5

What are the layers of the epidermis made of?

Answer 5

Keratin

Question 6

Stratum basale

Answer 6

divides to produce the rest of the layers

Question 7

Stratum spinosum

Answer 7

spiny protrusions, attached through desmosome, variable number of layers, large amounts of cytoplasmic keratin

Question 8

Stratum granulosum

Answer 8

differentiated, contain granules, secrete lipid layer between cells

Question 9

Stratum lucidum

Answer 9

thick skin only, translucent, no nucleus

Question 10

Stratum corneum

Answer 10

thickest layer, continually shedding

Question 11

What do keratinocytes undergo instead of apoptosis?

Answer 11

Cornification

Question 12

Specialised cells in the epidermis

Answer 12

Melanocytes, langerhans, merkel cells

Question 13

Describe melanocytes

Answer 13

specialised cells responsible for pigmentation. Have cytoplasmic projections that transfer melanin granules into keratinocytes. Melanocytes cover the nucleus of cells with melanin to protect from UV rays.

Question 14

Describe langerhans cells

Answer 14

phagocytes that migrate to lymph nodes when activated

Question 15

Describe Merkel cells

Answer 15

in the basal layer, responsible for fine touch and pressure sensing, high density in thick skin and lips

Question 16

Describe papillary layer of dermis

Answer 16

made of collagen, projects into stratum basale of epidermis to form finger-like dermal papillae which form epidermal/papillary ridges which in turn form fingerprints

Question 17

What does the papillary layer of skin contain?

Answer 17

fibroblasts, adipocytes, blood vessels, phagocytes, lymphatic capillaries, nerve fibres, and Meissner corpuscles (touch sensors)

Question 18

Describe reticular layer of dermis

Answer 18

much thicker than papillary layer, composed of dense irregular connective tissue (collagen and elastin), well vascularised, rich sensory and sympathetic nerve supply.

Question 19

Describe hypodermis

Answer 19

well-vascularised, loose areolar connective tissue and adipose tissue that provides insulation and cushioning. Connects skin to underlying fascia of bones and muscles.

Question 20

Terminal hair

Answer 20

pigmented and coarse, found on head, armpits, and groin

Question 21

Vellus hair

Answer 21

fine and unpigmented, found everywhere else on the body except for palms of hands and soles of feet.

Question 22

Lanugo hair

Answer 22

fine and pigmented, normally only found on new-borns, but is also seen on the arms/back of people with anorexia as a response to disrupted thermoregulation in an attempt to insulate the body

Question 23

Structure of hair

Answer 23

made of keratinised epithelial cells. Consist of a follicle (the living part under the skin’s surface) and hair shaft which is outside.

Question 24

Describe hair matrix

Answer 24

The hair matrix, containing the proliferating cells that generate the hair and internal root sheath, is found just above the dermal papilla and is separated from it by a basement membrane. The cells in the matrix proliferate and move upwards, gradually becoming keratinised to produce the hair

Question 25

Structures associated with hair

Answer 25

sebaceous glands, arrector pili muscles, and apocrine sweat glands, dermal papilla contains blood supply at base of follicle

Question 26

Layers of the hair matrix

Answer 26

From external to internal: outer root sheath, inner root sheath, cuticle (flattened squamous), cortex (compressed cuboidal) and medulla.

Question 27

Functions of hair

Answer 27

thermoregulation, protection, sensory input, and cosmetic/social aspects

Question 28

Hair growth phases

Answer 28

anagen, catagen, telogen, hair falls out, return to anagen

Question 29

Anagen phase

Answer 29

active growth phase, mitosis of matrix cells, lasts 2-6 years

Question 30

Catagen phase

Answer 30

regressing/transition phase, lasts 1-2 weeks

Question 31

Telogen phase

Answer 31

resting phase, dermal papilla separated from follicle, lasts 5-6 weeks

Question 32

Hair loss

Answer 32

anagen hairs is usually due to drugs e.g. chemotherapy – left with wispy telogen hairs until they fall out max. three months later.
Loss of telogen hairs usually after severe illness – left with bald patches.

Question 33

Pilo-sebaceous unit

Answer 33

made of hair, arrector pili muscle, and sebaceous gland

Question 34

Describe arrector pili muscle

Answer 34

small smooth muscle that connects obliquely to upper dermis and base of follicle, sympathetic innervation, contraction of muscles causes hairs to stand up, squeezes sebaceous gland so sebum is released to protect the hair

Question 35

Describe sebaceous gland

Answer 35

produces sebum in a holocrine process

Question 36

Holocrine process of sebaceous gland

Answer 36

cells rupture and disintegrate as they release sebum

Question 37

Describe sebum

Answer 37

lipid and oil rich, waterproofs and lubricates