week 19 (skin) the integumentary system Flashcards
what is the largest organ in the human body
skin
name some key roles the skin plays
protection from external environment
sensory
absorption (IV = vit D synthesis)
secretion (sweat, electrolytes, sebaceous oils, pheromones)
body temperature regulation (high surface area to body volume)
body reservoir
aesthetics
how many layers are there in the skin
3
what are the three layers of the skin (outer to innermost
epidermis
dermis
hypodermis
name 4 characteristics of the epidermis
outermost layer
epithelial
non vascular
protective
name 5 characteristics of the dermis
fibrous connective tissue
epithelial gland structures (sweat and sebaceous glands)
smooth muscle
vascular
sensory
what type of tissue is the dermis
fibrous connective tissue
what are the 2 epithelial gland structures in the dermis
sweat glands
sebaceous glands
which of the three layers in the epithelial system is not actually skin
hypodermis
name 4 characteristics of the hypodermis
not skin
protective
adipose and loose
connective tissue
structure of epidermis is composed of what kind of epithelium
thick keratinised squamous epithelium
how many layers are there in the epidermis
5
in the epidermis, it is consisted of how many epithelial cell types
4
what are the 5 layers in the epidermis (innermost to outermost)
stratum basale
stratum spinosum
stratum granulosum
stratum lucidum
stratum corneum
what are the 4 cell types in the epidermis
keratinocytes
melanocytes
Langerhans cells
merkel cells
in the stratum basale what occurs
cells divide by mitosis and some of the newly formed cells become the cells of the superficial strata
what occurs in the stratum spinosum
keratin fibres and lamellar bodies accumulate
what occurs stratum granulosum
keratohyalin and a hard protein envelope form; lamellar bodies release lipids and die
what is the envelope that is formed in the stratum granulosum (within the epidermis) composed of
keratohyalin and a hard protein envelope
in the stratum lucidum what do the dead cells contain
dead cells containing dispersed keratohyalin’s
what occurs in the stratum corneum
dead cells with a hard protein envelope - the cell contain keratin and are surrounded by lipids
in the epidermis, what is the role of keratinocytes
produce keratin and are the primary cell os epidermis
keratinocytes are the key cell involved in what
wound healing
keratinocytes are connected by what
desmosomes
filaggrin causes keratin fibres to what
dimerise (keratinisation)
what protein causes keratin to dimerise (keratinisation)
filaggrin
mutations in profilaggrin cause what condition
eczema
in the epidermis, the granule layer is composed of what 3 types of keratin
1, 2, 10
in the spinous layer, as cells grow upwards, they express what enzyme to cross link junction complexes
transglutaminases
in the spinous layer, as cells grow upwards they express transglutaminases which does what
cross link junction complexes
in the cornified layer within the stratum corneum, cells die and the cornified layer forms. Fillagrin is hydrolysed to what
amino acids
in the cornified layer within the stratum corneum, cells die and the cornified layer forms. Fillagrin is hydrolysed amino acids which form what
a protective water proof barrier
in the epidermis, what is the role of melanocytes
produce pigment - melanin
where are melanocytes located
stratum basale
what are merkel cells
neuroepithelial cells associated with sensory nerve ending
what do merkel cells act as
mechanoreceptors
what neurotransmitter are used by merkel cells
glutamate
what are merkel cells sensitive to
shear and pressure
where are langerhan’s cells made (and where do they migrate to)
bone marrow and migrate to epidermis
how do langerhans cells function
as macrophage like antigen presenting cells (activate T cells)
how is melanin synthesised
tyrosinase
conversion of tyrosine through multiple reactions to o-Quinone and ultimately melanin
when melanin is converted from tyrosinase where does this occur
melanocytes
in what step in melanin synthesis decides if you are black/white
dopaquinone (lack of enzymes)
in melanin synthesis production of eumelanin ends in what colour
black
in melanin synthesis production of pheomelanin end in what colour
red
does UVA or UVB have a longer wavelegth
UVA
UVA penetrates what layer of the skin
dermis
what layer of the skin does UVB causes sunburn and penetrates what layer of the skin
epidermis
how is alpha melanocyte stimulating hormone synthesised and released
damaged dermal cells
how many transmembrane subunits are there in the MC1R
7
MC1R activated MITF transcription factor where
in melanocytes
In melanocytes, MC1R activates what
MITF transcription factor
where us the alpha melanocyte stimulating hormone produced
dermis
the MC1R drives expression of what
tyrosinase, DCT, and TRP1 (favouring eumalanin black synthesis
how can you develop carotene
from diet
deposited in stratum corneum and fatty tissue of hypodermis as a yellow-orange colour
how can you develop erythema
re-direction of blood flow to superficial skin capillaries due to irritation, infection or as part of a response to fever
how does blushing occur
catecholamines induced vasodilation which pushes blood to skin surface in well perfused areas of skin
how do you develop jaundice
liver disease releases bile pigments to blood which are deposited in the hypodermis and the cornea of the eye giving a yellow colour
how does bruising develop
injury to capillaries of dermis and hypodermis results in deposits of bilirubin in skin which cause colours of bruise (blue/orange/green)
the strength of the dermis comes what 2 layers
papilary and reticular
in what direction is eccrine (merocrine) secreted
exocytosis
what does apocrine secrete
lipid, protein, and amino acid laden
what skin appendage gland is often waxy
holocrine
nails are composed of what
keratin
what do nails do
protects tips from damage and aids in precision of movement
what are the three phases of hair growth
rest (telogen)
growth (anagen)
cessation (catagen)
how many phases are there in hair growth
3
what is hair composed of
keratin
what does hair aid in
thermoregulation
how many skin glands are there
5
what are the 5 types of skin glands
eccrine sweat glands
apocrine
sebaceous glands
ceruminous glands
mammary glands
