Tissues 10-11 Flashcards
Functions of the skin?
- Protection
- Waterproofing and fluid conservation
- Thermoregulation
- Absorption of UV and vitamin D production
- Sensory organ
- Cosmetic
What is toxic epidermonecrolysis?
Rare condition whereby keratinocytes undergo mass apoptosis.
What is psoriasis?
Common skin condition (15%) due to excess keratinocytes.
Where does the herpes-zoster virus live?
Dorsal root ganglions
How many layers are there to the epidermis?
4
What are the four layers of the epidermis?
1) Stratum corneum
2) Stratum granulosum
3) Stratum spinosum
4) Stratum basale/parabasale
What is a markel cell?
Involved in touch and sensation. Located in basement membrane.
What are melanocytes?
Cells that produce melanin (a pigment giving us our skin colour) to protect the keratinocytes from UV damage. 1:5 ratio.
What does the basement membrane do?
Join the epidermis and dermis
What is eccrine?
Watery sweat that is distributed all over the body.
What is apocrine?
Thick, viscous sweat that is secreted in certain areas such as the groin and axillary regions. Prone to bacterial metabolism and therefore odour.
What is the embryology of the epidermis?
Ectoderm
What is the embryology of the dermis?
Mesoderm
What is the embryology of melanocytes?
Neural crest
What are the functions of hair?
- Protection against UV damage
- Sensation
- Thermoregulation
- Communication
Where are the only places with no hair?
Palms and soles of the feet
When does hair start growing in pregnancy?
Third trimester
What is lanugo hair?
Long, wispy hair that is common in young children and anorexics.
What is vellus hair?
Body hair (unpigmented and wispy)
What is terminal hair?
Pigmented, coarse hair found on the scalp and in facial hair
What are the four stages of the hair cycle?
Anagen - growing phase
Catagen - regression phase
Telogen - resting phase
Exogen - shedding phase
When does hair growth become asynchronous?
After the first exogenous phase.
What is the cause of male-pattern baldness?
Decrease in androgens.
What is hirsutism?
Excessive hair growth due to high levels of androgens.
What are the function of nails?
- Cosmetic
- Grip
- Weapons
- Touch
What do clubbed fingers indicate?
Cardiovascular or respiratory disease.
What is koilonychia?
Spoon-shaped nails that indicate iron deficiency anaemia.
