Skin Flashcards
Recall points for ‘skin’
Intro Epidermis Dermis Features of skin Glands
What is the skin ?
The largest organ in the body which contains its own nerve and blood supply
Why is the skin important clinically ?
- First organ you notice in a patient
- It has its own pathology
- It can provide evidence of underlying conditions
Examples of pathology of the skin
Sunburn
Acne
Eczema
Melanoma
Example of underlying conditions which can be seen in the skin
liver disease
What are the functions of the skin ?
Immune surveillance
UV protection
Energy store
Sensory information
What are the two layers of the skin ?
Epidermis
Dermis
What is the basic function of the epidermis ?
Prevents water loss from the surface through evaporation
What is the basic function of the dermis ?
Reduced risk of external injury
Maintains epidermis by its blood supply
permits body cooling
What is the hypodermis ?
Layer found under the dermis but not skin as it is just adipose tissue.
What is the function of the hypodermis ?
Anchors skin to underlying structures
Describe the significance of the thickness of the epidermis
Thickens varies around the body depending on the function.
Skin is thick on the hands while it is thin on the abdomen.
Which layers of the skin vary the most in thickness?
Stratum corneum and the dermis.
What are the names of the 4 cells found in the epidermis ?
Keratinocytes
Melanocytes
Langerhans cells
Merkel cells
Describe the role of Keratinocytes in the epidermis of the skin
Most frequent, contains keratin, is hard and resistant to abrasion.
Extruding lipids mean that it is water proof.
Continually dividing to repair from damage
Describe the role of Melanocytes in the epidermis of the skin
Pigment formation
Describe the role of Langerhans cells in the epidermis of the skin
Immune surveillance
Describe the role of Merkel cells in the epidermis of the skin
Touch receptors
Name the 5 layer of the epidermis
Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale
Describe the Stratum corneum
no organelles, flat dead cells containing keratin
Describe the Stratum lucidum
Where keratohyalin is converted to keratin.
It has a 15-30 day turnover.
Describe the Stratum granulosum
contains granules that are made of keratohyalin
Describe the Stratum spinosum
Preparation layer for keratinisation
Describe the Stratum basale
Contains tall columnar cells interspersed with melanocytes and Merkel cells,.
It is bound to BM by hemidesmosomes and forms an irregular interface with the dermis creates dermal papillae which strengthens the join between the two layers.
What is kertinisation ?
Organic process whereby keratin is deposited in cells and these become horny as in dead skin, nails, hair
What are the names of the two layers of the dermis ?
The papillary layer
The reticular layer
Describe the papillary layer
it contains loose connective tissue and cells such as macrophages.
It has an irregular interface with the epidermis.
What are the functions of the papillary layer?
- Protects against pathogens
- Contains blood vessels for thermoregulation
- Contains nerve endings which allow the skin to be a sense organ
Describe the reticular layer
It is a layer of dense tissue which contains elastic fibres which are found in three planes to skin the skin support. The elastic fibres are then lost in old age
List the features of skin
Colour Hair Nails Sense organ Thermoregulation Glands
Describe the skin feature of colour
Skin colour depends on the flow of blood through it and the carotene consumed in the diet.
The skin colour also is dependant on the melanin found in it which protects against UV.
Which layer is hair derived from ?
Epithelial layer
What is the practical use of hair ?
Used in skin repair
How does a hair follicle develop ?
A hair follicle is formed by the downward growth of epithelial cells. This follicle is then invaded by blood vessels and the hair begins to grow
What are two important structural features of the skin ?
- The arrector pili muscle
- Sebaceous glands
Describe the arrector pili muscle
This is a muscle which is attached to the follicle root and base epidermis. It is at an angle and when it contracts it pulls the hair straight.
Describe the sebaceous gland
A sebaceous gland forms between the follicle and the arrector pili muscle. It secretes sebum and its function is uncertain.
What is a nail plate made of ?
Keratin
What part of the finger does a nail plate grow out of?
A nail bed
What is the nail bed made of ?
Specialised epithelium which has the same four layers are the normal epithelial. Here the stratum corneum is the nail plate.
What is another name for the cuticle ?
The eponychium
Describe the eponychium
Thickened layer of skin surrounding the fingernails and toenails which functions to protect the area between the nail and epidermis from exposure to bacteria
What is the hyponychium ?
The area of epithelial particularly the thickened portion underlying the free edge of the nail plate
What are the four types of sensory receptor found in the skin
1. Meissner’s corpuscles - light touch - fingertips 2. Paccinian corpuscles - vibration & pressure 3. Pain receptors 4. Thermoreceptors
The skin is used for thermoregulation. What things allow for this regulation ?
Sweat glands
Blood vessel dilation
Hair
There are glands in the skin. What are the two types ?
Sebaceous
Sweat glands
Describe sebaceous glands
Hair follicles
Holocrine glands
Secretes sebum
Describe sweat glands
Eccrine - Normal
Apocrine - Pubic
What are the structural features of sweat glands ?
Simple tubular glands Located in the dermis Coiled secretory portion Coiled and straight duct in dermis Spiral channel in epidermis Watery secretion Thermoregulation
What kind of cells makes up the epidermis the of the skin ?
Stratified squamous epithelial
What kind of cell make up the stratum basel of the skin?
Tall columnar epithelium
What kind of tissue is the dermis of the skin ?
Loose connective tissue
