W2 - Layers of Skin Flashcards
List layers of skin from most external to most internal
Epidermis, dermis, hypodermis/subcutis
The keratinocytes in the epidermis undergo upward migration during maturation, list the order of layers
Basal layer, stratum spinosum, granular layer, stratum corneum
Why is there an upward migration of keratinocytes in the epidermis?
The cells at the surface are constantly shed so they need to constantly proliferate
How many layers is the basal layer and what do the cells look like?
1 layer - cuboidal or low columnar
How many layers is the stratum spinosum and what do the cells and nuclei look like?
Multiple layers - irregular cell shape, oval nuclei
What happens in the granular layer of the epidermis and are the granules basophilic or acidophilic?
Keratinisation, basophilic
What happens during keratinisation?
Cells undergo their final differentiation stage, keratin polypeptides are synthesised and are formed into keratin intermediate filaments
What are the water repellent cells called in the stratum corneum and what is special about their contents?
Keratin squames - no nuclei or organelles
What are the two layers of the dermis called? Most to least external
Papillary dermis and reticular dermis
What are the peaks towards the surface and towards internal surfaces of papillary dermis called?
Surface - dermal papillae, Internal facing - rete ridges
What is the difference between the collagen fibre bundles + elastic fibres in the papillary and reticular dermis?
They’re thicker in the reticular dermis
The papillary dermis has looser connective tissue and is what?
Highly vascular
Where can sensory receptors on nerve endings be present?
In the papillary dermis
What is the intercellular substance of tissues called?
Ground substance
What makes up the hypodermis/subcutis in terms of tissue?
Adipose tissue and fibrous bands (septa)
Thickness and ………… (done by septa) varies from site to site in the subcutis
Partial compartmentalisation
Where are there usually no hair follicles or apocrine glands?
Subcutis/hypodermis
What is mesenchymal tissue?
Embryological tissue from which all connective + supportive tissues are derived
What two shapes can mesenchymal tissue cells be?
Stellate and fusiform
What two supportive tissues does mesenchymal tissue have?
Collagen and reticulin
Definition of Epidermis
Stratified squamous keratinised epithelium divided into 5 strata
Definition of dermis
Dense irregular connective tissue that supports epidermis
Definition of hypodermis/subcutis
Loose connective tissue with adipose tissue
Definition of the dermal papillary layer
Papillae that project into the dermis
What does the dermal papillae do?
Increases adhesion between epidermis and dermis
Definition of the dermal reticular layer
Dense, irregular connective tissue
What do the keratinocytes in the granular layer contain?
Basophilic keratohyalin granules
What do the keratinocytes in the stratum spinosum attach by?
Desmosomes on spiny processes
What are the keratinocyte cells called in the basal layer of the epidermis?
Germinal cells
Are keratin squames living or dead?
Dead
