Intro to Derm Flashcards
true/false - skin is the largest organ in the body
true
what sort of structures does skin contain
adnexal (skin associated) structures - eg hair, nails, glands, sensory structures
from the outside to inside what are the three layers
- epidermis
- dermis
- hypodermis (subcutis)
what is structure and function of the the sub cutis layer
fat energy store, fibrous bands anchor skin to fascia, insulation
what is the structure of the dermis layer
collagen and elastin matrix with mucopolysaccharide gel - fibroblasts, dermal dendritis cells and macrophages
what is the structure of the epidermis
5 layers (in-out)
- stratum basale
- stratum spinosum
- straum granulosum
- stratum lucidum
- stratum corneum
what are the three main cell types in the epidermis
- keratinocytes (skin cells)
- melanocytes (pigment-producing cells)
- langerhans cells (immune cells)
what is the role of langerhans cells
process antigens and migrate to lymph nodes to induce an immune response
what is the role of melanocytes
make melanosomes (collections of melanin) - excreted and phagocytosis into keratinocytes where they sit above the nucleus
how does the epidermis get its nutrients
through diffusion as it is a-vascular
what occurs at the stratum basale
cells divide by mitosis and some of the newly formed cells become the cells of the more superficial strata
what occurs at the stratum spinosum
keratin fibres and lamellar bodies accumulate
what occurs at the stratum granulosum
keratinohyalin and a hard protein envelope form - lamellar bodies release lipids - cells die
what occurs at the stratum lucidum
dead cells lie within dispersed heratohyalin
what occurs in the stratum corneum
dead cells with a hard protein envelope - cells contain keratin and are surrounded by lipids - cells slough off
how would a melanoma at the nail matrix present
a dark strip going along the nail from matrix to hyponychium
what are the three stages in the hair cycle
- anagen
- catagen
- telogen
what is the anagen stage
active growing stage - 80-90% of hair
what is the catagen stage
2-3 week phase where growth stops/follicles shrink - 1-3% hair
what is the telogen stage
resting phase for 1-4 months - up to 10% of hair in a normal scalp
what are the functions go skin
- thermoregulation
- skin immune system
- barrier
- sensation
- vit D synthesis
- interpersonal communication
how does the skin thermoregulate
- insulation, heat transfer
how is the skin part of the immune system
innate - eg sweat, non-pathogen specific mechanism
adaptive - antigen presenting cells, antibody production
how is the skin a barrier
protects against mechanical, chemical, microorganisms and UV light
keeps in water and electrolytes, macromolecules
