Structure of skin

Question 1

Layers of epidermis in order top to bottom

Answer 1

Stratum corneum (horny layer)
Stratum lucidum (clear)
Stratum granulosm (granular)
Stratum spinoseum (prickle cell)
Stratum germinativum (basal or germinating)

Question 2

Describe Stratum Corneum

Answer 2

Outer layer made up of scale like cells that continually shed (cornflakes)

Question 3

Describe Stratum Lucidum

Answer 3

Made of small transparent cells through which light can pass. Only present in palms and soles of feet.

Question 4

Describe Stratum granulosum

Answer 4

usually 1-3 layers thick. Cells have distinct granules and keratin is produced in this layer

Question 5

Describe Stratum spinosum

Answer 5

3-6 layers thick cells are constantly dividing

Question 6

Describe Stratum germinativum

Answer 6

Single basal layer of cells which contain melanocytes that produce the pigment melanin. The cells of the epidermis are produced in this layer and each has a distinct nuclei. These cells divide continuously by a process known as mitosis.

Question 7

How does hyper pigmentation occur?

Answer 7

When the melanocytes over secrete.

Question 8

What happens if melanocytes under secrete or stop secreting?

Answer 8

hypo-pigmentation or vitiligo

Question 9

Description of dermis.

Answer 9

2 layers papillary and reticular. Good blood and lymph supply provided by lymph capillaries, arterioles and venules. Made up of connective tissue.

Question 10

Description of papillary layer.

Answer 10

lies directly under the epidermis. Quite thin and has cone like projections called papillae. Provides nutrients and oxygen to the germinating layer of the epidermis.

Question 11

Description of reticular layer

Answer 11

lies below papillary main section of dermis. Contains collagen and elastin These fibres are produced by fibroblasts and all held together in a ground substance. While the network is strong the skin will remain youthful and firm but as the fibres start to harden and split the network collapses and the ageing process starts to become visible. The appendages are also located in the dermis.

Question 12

Description of the subcutaneous layer

Answer 12

under the dermis mainly made up of fat cells (adipose tissue) This fatty layer provides the plump contours of the body protection, insulation and support and food supply if needed.

Question 13

Description of sweat glands

Answer 13

sudoriferous glands extend from the epidermis in to the dermis found all over the body, Regulate body temp. esp. numerous in palms and soles.

Question 14

What are the two types of sweat glands

Answer 14

Aprocrine - larger and deeper found in the groin and under arms. Under hormonal control become active at puberty.
Eccrine - found all over the body secrete in response to heat.

Question 15

what is the hair follicle?

Answer 15

Indentation of epidermis with the walls of the follicle being formed from a continuation of the cellular layer of the skins surface.

Question 16

what is the inner root sheath?

Answer 16

Layer of the follicle closest to the hair has scale like cells that interlock with the cuticle to hold the hair firmly in place. The hair and the inner root sheath grow upwards together. the inner root sheath is made up of three layers - cuticle of inner root sheath, Henley’s layer and Huxley’s sheath

Question 17

What is the outer root sheath?

Answer 17

This is the follicle wall does not grow upwards but remains stationary.

Question 18

What is the connective tissue sheath?

Answer 18

surrounds the rest of the follicle and the sebaceous gland. Extension of the papillary layer of the dermis and provides a sensory nerve and blood supply.

Question 19

what is hair?

Answer 19

Dead structures made of keratin (hardened protein). Keratin provides the body with a protective toughness for it’s entire surface.

Question 20

Three areas of the hair?

Answer 20

Shaft - lies above the skin surface and runs through the centre of hair.
Root - lies under the skin inside the follicle.
Bulb - The large base at the bottom of the root and this encases the dermal papilla. the matrix is the lower region of the bulb where the cells divide rapidly to produce the new hair and follicle structure.

Question 21

The three layers of the hair?

Answer 21

Cuticle - outer layer of scale like keratinised cells. No pigment protects hair.
Cortex - Main part. Elongated cells. Colour here. Strength thickness elasticity are held together.
Medulla - middle spongy. Not in vellus or fine terminal hair.

Question 22

How is blood supplied to skin?

Answer 22

by capillaries. Arterioles supply oxygenated and venules remove waste. Capillaries also help maintain body temp by dilating and constricting.

Question 23

What is dermal papilla and what is it’s function?

Answer 23

Blood supply for hair and its follicle. It provides food and oxygen essential for growth of hair. A separate organ.

Question 24

Function of arrector pilli?

Answer 24

Muscle attached to follicle contracts when you are cold or frightened causing hair to stand up. this traps layer of warm air.

Question 25

What are sebaceous glands?

Answer 25

Found all over body except palms of hands and soles of feet produce sebum. Gland attached to upper part of follicle duct enters directly in to the hair follicle. More active at puberty due to levels of androgen. Men secrete more and they become less active as we get older.

Question 26

Function of sebum?

Answer 26

Bactericidal and fungicidal prevents against infection provides protection and stop skin dry out.

Question 27

How sensory nerve endings work?

Answer 27

detect changes in environment send messages to the central nervous system which will send messages back via the motor nerves to stimulate a response.

Question 28

Functions of the skin?

Answer 28

Sensation, Heat regulation, absorption, Protection, Excretion, secretion, vitamin d production.

Question 29

Characteristics of black skin

Answer 29

usually looks shiny. thicker epidermis. Produces more sebum and sweat. Less hair. Desquamates quicker skin looks grey. erythema looks purple. Hair follicles curved. Prone to irregular pigmentation after waxing.

Question 30

Characteristics of Asian skin

Answer 30

irregular pigmentation around eyes mouth, Sweat glands larger and more numerous, Skin usually ages well.

Question 31

Characteristics of white skin

Answer 31

premature ageing. Thin prone to freckles. Fewer and less active sebaceous glands.

Question 32

Characteristics of Chinese skin

Answer 32

more melanin that white. not many blemishes sebaceous glands less active. scarring more likely to occur resulting in unevenness, hyper-pigmentation and pitting.