Biology of Skin

Question 1

Name the 3 main layers of skin

Answer 1

1) Epidermis
2) Dermis
3) Subcutis/hypodermis

Question 2

What structure of cells make up the epidermis

Answer 2

keratinised stratified squamous epithelium, cornified

Question 3

Name the layers of the epidermis in order of outer most surface first

Answer 3

1) Cornified layer
2) Granular layer (stratum granulosum)
3) Spinous layer (stratum spinosum)
4) Basal layer (stratum basale)

Question 4

What is the function of the basal layer?

Answer 4

Contains stem cells of the epidermis.

Question 5

What is the function of the spinous layer

Answer 5

thicker layer of the epidermis. desmosomes (tight junctions) between cells gives epithelia their properties of things like high electrical resistance

Question 6

What two molecules does the granular layer contain and what is their function?

Answer 6

Keratohyalin granules (contain keratin) and lamellar bodies (contain lipids) which provide a hydrophobic barrier to water.

Question 7

what is unique about cells in the cornified layer

Answer 7

cells undergo apoptosis to form the tough surface layer of the skin. shed in a process called desquamation

Question 8

What is the name of the cell responsible for skin pigmentation and protection against UV damage?

Answer 8

Melanocytes

Question 9

What are Langerhans cells

Answer 9

antigen presenting cells of the epidermis

Question 10

What do merkel cells do?

Answer 10

in association with nerve fibres responsible for fine touch sensation

Question 11

What are the two layers of the dermis called?

Answer 11

papillary dermis and reticular dermis

Question 12

what type of fibres make up the papillary dermis?

Answer 12

collagen and elastin fibres - gives skin its flexibility

Question 13

Which part of the dermis do you find fibroblasts and what do they secrete?

Answer 13

in the reticular dermis.

they secrete collagen

Question 14

What part of the skin do you find various skin appendages such as hair follicles and glands?

Answer 14

Reticular dermis

Question 15

What is the hypodermis predominantly made up of and what is its function

Answer 15

adipose tissue. functions as insulator, protector and E source

Question 16

What is sweat comprised of?

Answer 16

water, sodium ions, chloride ions, urea and some low mol. wt. metabolites

Question 17

by what type of secretion is sweat secreted?

Answer 17

Merocrine secretion

Question 18

Where are apocrine glands found on the body?

Answer 18

axillae, mammary and groin regions

Question 19

What do aprocrine glands secrete?

Answer 19

viscous, cloudy secretion which may contain pheromones and cause body odour upon reaction with skin bacteria

Question 20

What do sebaceous glands secrete and what is the purpose of this substance?

Answer 20

Sebum, a lipid containing substance which coats hair keeping it soft, supple and waterproof

Question 21

What method of secretion do sebaceous glands use?

Answer 21

Holocrine secretion - acinar cells become distended with increasing lipid contents and die, releasing their contents

Question 22

Name the 5 physiological functions of skin

Answer 22

1) Thermoregulation
2) Sensation
3) Vitamin D synthesis
4) Immunological Role
5) Protection against UV radiation

Question 23

Name the 5 phases of healing involved in deep wounds that extend into dermis

Answer 23

1) Haemostasis
2) Inflammation
3) Fibroplasia
4) Epithelialisation
5) Remodelling

Question 24

What layers would you find fluid filled lesions such as blisters?

Answer 24

Within epidermis or at epidermis-dermis junction

Question 25

Define scaling

Answer 25

shedding of cornified layer

Question 26

Define callus

Answer 26

hyperplasia of epidermis following pressure or friction

Question 27

define erosion

Answer 27

loss of superficial epidermis

Question 28

define ulcer

Answer 28

loss of epidermis and papillary layer of dermis

Question 29

define bruising

Answer 29

leakage of blood into dermis