Organ-specific immunity: SKIN Flashcards
In what 4 ways does the skin act as a barrier?
Physical, microbiota, chemical, immune
Why do people that suffer from food allergy also often suffer from itchiness?
There is a skin-gut axis due to similar homing molecules
What are the main skin functions? (6)
- Protection/defense
- Signal reception
- Thermoregulation
- Communication
- Secretion
- Absorption
How does the skin thermally regulate the body?
Sweating, vasoconstriction/dilation
What is sebum?
A sticky, oily substance produced by the sebaceous glands
What can skin absorb?
Light, pharmaceutics
What are the three main layers of the skin?
Epidermis, dermis, hypodermis
What does the epidermis consist of?
Keratinocytes in 5 stratum layers:
- Corneum
- Lucidum
- Granulosum
- Spinosum
- Basale
Where are langerhans cells located?
The stratum spinosum
What does the stratum basale consist of?
Basal cells (stem-cell like keratinocyte precursors), Merkel cells and melanocytes
What do lamellar granules do in the skin
Play a role in keratinization
What is the function of the stratum lucidum?
Water resistance and barrier
What does the stratum corneum consist of?
Dead cells
What is the site of entry of microbiota?
The glands and hair follicles
What prevents invasion of microbiota into the hair follicles and glands?
Monocytes and Tregs
How do keratinocytes attach to the basal lamina?
Hemidesmosomes
What does the basal lamina consist of?
Type IV collagen, laminin and proteoglycans
What do desmosomes do?
They interconnect keratinocytes to each other, provide structural integrity but still allow passage of substances
How is transport of substances limited in the epidermis?
Tight junctions, particularly in the stratum granulosum, enforcing cytoplasmic uptake
Is all keratin expressed in skin cells the same?
No, different cells have different types of keratin made up of heterodimers of keratin with different functions (barrier, metabolism, differentiation, etc)
How is photoprotection provided?
- Melanocytes produce melanin and form melanosomes
- Melanosomes are exocytosed
- Melanosomes are endocytosed by keratinocytes
- Exposure to sunlight causes migration of melanosomes to apical side of keratinocytes to protect
What do Merkel cells do?
They are specialized epithelial cells especially present in thick skin. They are in close contact with sensory nerves and aid in perception of light touch
What is the reticular dermis?
Makes up the bulk of the dermis, made up of tight connective tissue
What are the two dermis layers?
Papillary dermis and reticular dermis