Anatomy of the Skin Flashcards
How many layers of the skin are there?
3
What are the three main layers of skin called?
-Epidermis
-Dermis
-Hypodermis
What is the epidermis mainly formed from?
Keratinocytes undergoing terminal maturation
What other cells occupy the epidermis?
-Melanocytes
-Langerhans cells
-Merkel cells
What are melanocytes responsible for?
The are responsible for melanin production and pigment formation
What are Langerhans cells?
Antigen-presenting dendritic cells
What are Merkel cells?
Sensory mechanoreceptors
What is the epidermis divided into?
Layers of keratinocytes
What are the different layers of the epidermis?
-Stratum basale
-Stratum spinosum
-Stratum granulosum
-Stratum lucidum
-Stratum corneum
Which layer of the epidermis is the deepest from the surface?
Stratum basale
What occurs in the Stratum basale layer of the epidermis?
Mitosis of keratinocytes
How are keratinocytes joined in the Stratum spinosum layer of the epidermis?
Joined by tight intercellular junctions called desmosomes
What occurs in the Stratum granulosum layer of the epidermis?
Cells secrete lipids and other waterproofing molecules
What occurs in the Stratum lucidum layer of the epidermis?
Cells lose nuclei and drastically increase keratin production
What occurs in the Stratum corneum layer of the epidermis?
Cells lose all organelles and continue to produce keratin
How many days does a keratinocyte take to travel from the Stratum basale to the Stratum corneum?
30-40 days
Where is the dermis found?
Right below the epidermis
How many layers does the dermis have?
2
What are the two layers of the dermis called?
-Papillary Layer
-Reticular Layer
What function do the thicker bundles of collagen fibres have on the reticular layer of the dermis?
Provides durability
What helps provide the reticular layer of the dermis durability?
Thicker bundles of collagen fibres
What are some of the cell types and structures found in the dermis layer?
-Fibroblasts
-Mast cells
-Blood vessels and cutaneous sensory nerves
-Skin appendages
What is the function of a fibroblast?
Cells which synthesis the extracellular matrix
What are fibroblast composed of?
-Collagen
-Elastin
What are mast cells?
Histamine granule-containing cells of the innate immune system
What are some examples of skin appendages?
-Hair follicles
-Nails
-Sebaceous and sweat glands
What do hair follicles and sebaceous glands combine to form?
Pilosebaceous Unit
Where is the hypodermis layer found?
Immediately below the dermis layer
What is found in the hypodermis layer?
Adipose tissue
What is another word for adipose tissue?
Body fat
What are all the functions of the skin?
7
-Defence against infections and infestations
-Protection against irritants, ultraviolet irradiation and injury
-Controlling water and heat loss
-Important sensory organ which distinguishes pain, touch, itching, vibrations, heat and cold
-Maintain body temperature
-Vitamin D is also synthesised in the skin
-Important organ of social communication and sexual contact.
