Skin Flashcards
What are 7 functions of the skin?
- Excretion via sweat
- Physical protection
- Water retention
- Sensory information
- Barrier against UV
- Temperature regulation
- Manufactures vitamin D
What are the 2 layers of the skin?
- Epidermis
2. Dermis
What are the 2 types of skin?
- Thick Skin
2. Thin Skin
Where is thick skin found?
Palms of the hand and soles of the feet
Besides thickness, what is the major difference between thick and thin skin?
Absence of hair follicles on thick skin
What type of tissue is the epidermis?
Stratified squamous keratinising epithelium
What are the 4 cell types present in the epidermis?
- Keratinocytes
- Melanocytes
- Merkel Cells
- Langerhans Cells
What is the function of keratinocytes?
Produce keratin
What is the function of keratin?
Helps with water retention and waterproofing of skin
What is the function of melanocytes?
Synthesise pigment melanin
What is the function of melanin?
Protect against UV
Where are melanocytes found?
Basal layer of the epidermis
Where is melanin stores?
Melanosomes
What is the function of Langerhans cells?
Part of the immune system
What is the function of Merkle cells?
Function as mechanoreceptors i.e. detect shape
What are the 5 strata of the epidermis in ascending order?
- Stratum Basale
- Stratum Spinosum
- Stratum Granulosum
- Stratum Lucidum (Thick Skin only)
- Stratum Corneum
What cells are found in the stratum basale?
Single layer of cuboidal cells
What binds stratum basale to the basal lamina and dermis?
Hemidesmosomes
At what strata of the skin does active cell division take place?
Stratum basale
What cells are found in the stratum spinosum?
2-8 layers of prickle cells
What causes cells to have a prickle appearance in stratum spinosum?
Desmosomes hold cells together but the rest of the membrane contracts
What cells are found in the stratum granulosum?
2-3 layers of squamous cells
At what strata does the nucleus being to break down?
Stratum granulosum
What cells are found in the stratum corneum?
Cells with no organelles composed almost entirely of keratin
What is the function of the lamellar body?
Produce lipids which are secreted to waterproof skin
What type of tissue is the dermis?
Dense Irregular Connective Tissue
Name 5 elements contained within the dermis
- Fibroblast
- Collagen fibres
- Elastic fibres
- Nerve fibres
- Blood and lymphatic vessels
What are the 2 layers of the dermis?
- Papillary
2. Reticular
What is the papillary layer of the dermis?
Superficial region which interdigitates with epidermal ridges
What is the reticular layer of the dermis?
Deeper region which is attached to underlying hypodermis
What is the function of collagen fibres in the dermis?
Provide high tensile strength
What is the function of elastic fibres in the dermis?
Provide elasticity and recoil of skin
What is the hypodermis?
Connective tissue layer immediately deep to skin
Name 3 epidermal appendages
- Sweat glands
- Hair follicles
- Sebaceous glands
What are the 2 types of sweat gland?
- Merocrine
2. Apocrine
What is the arrector pili muscle?
Muscle found at the base of hair follicle which allows it to stand
What is the function of the sebaceous gland?
Secrete sebum onto hair follicle
Name 3 functions of sebum
- Soften and lubricate hair
- Slow water loss
- Bactericidal function
What word best describes sebaceous glands with regards to their release of sebum
Holocrine
