The Integumentary System (/Skin) Flashcards
What are the five functions of the integumentary system?
- Protection
- Synthesis and storage or nutrient (Vitamin D3 synthesis)
- Temperature maintenance
- Sensory reception
- Excretion and secretion
What does the integumentary system consist of?
Skin and accessory strucutres
How many layers does the skin have?
Epidermis, dermis, hypodermis
Examples of accessory structures
Glands (2 sweat glands, sebaceous gland), hair, nails
What are the two types of skin?
Thick skin and thin skin
Where might thick skin be found and give some characteristics?
Palm of hands, sole of feet
No hair 5 layers (stratum)
stratified, squamous, keratinised epithelium
Where is thin skin found and how many layers does it have?
Rest of the body
4 layers
Which layer of skin regenerates throughout life?
Epidermis
Epidermis and keratinocytes
Keratinocytes are born in the lower layer and migrate upwards during their life
Where are dead keratinocytes found?
On the very lateral of the epidermis
What are the five stratum in the epidermis?
Basal Spinosum Granulosum Lucidum Corneum
What 3 cell types are found in stratum basale?
Keratinocytes - majority, mitotic in this strata
Melanocytes - responsible for skin colour
Tactile (/Merkel) cells - connected to sensory nerves and participate to the sense of touch
Give 2 examples of pigments from melanocytes
- Eumelanin: brown insoluble pigment
- Pheomelanin: red soluble pigment
What is the thickets layer of the epidermis?
Stratum spinosum
Stratum spinosum characteristics
Keratinocytes - still mitotic
- higher content in keratin
- cells detach from the basement membrane and migrate apically
What is the last layer of the epidermis to have cells containing nuclei?
Stratum granulosum
How many layers of flat keratinocytes does stratum granulosum contain?
3-5
Stranum granulosim characteristics
Keratinocytes- post mitotic, make large amount if keratin and a glycolipid
Keratin forms filaments that are durable
Glycolipid spreads over keratinocytes and make the skin water-resistant
Which strata only exists in thick skin?
Stratum lucidum
What are the keratinocytes like in stratum lucidum?
Densely packet and contain no nuclei or organelles
Which strata is the most superficial layer?
Stratum corneum
Stratum corneum characteristics
15-30 layers of dead, keratinised cells
- high lipid content –> permeability barrier
What happens to cells at the surface of stratum corneum?
Cells at the surface flake off
Mnemonic to remember layer (inwards to outwards)
Basic spiny grans look corny
Is the dermis or epidermis thicker?
Dermis
How many layers does the dermis have and what are they?
- Papillary layer
- Reticular layer
In which of the 3 layers are blood vessels present?
Dermis
Which layer is also called the subcutaneous layer?
Hypodermis
What does the hypodermis consist of?
Connective tissue with adipocytes
Examples of cutaneous glands
mammary glands, ceruminous glands, sebaceous glands, sweat glands
Two types of sweat glands
Apocrine and merocrine
Where do apocrine glands secrete product?
These sweat glands secrete products into hair follicles of armpits
Which sweat glands secrete product into hair follicles of armpits?
Apocrine glands
Which sweat glands are heavily involved in thermoregulation?
Merocrine glands
Three ways in which skin is a barrier
Physical - toughness of keratin
Biochemical - Sebum contains bactericidal substances and sweat bring the pH down
Immunological - Langerhans cell in epidermis trigger immunological response during infection
Which strata are Langerhans cells present in the epidermis?
Stratum spinulosum
Which strata is vitamin D3 produced in?
Stratum basale and spinulosum
Where is vitamin D3 further processed? What does this produce?
In the liver and kidneys to produce the cofactor of VDR (vitamin D receptor) that acts as a transcription factor
