Integumentary Flashcards
What is the outer layer of skin and what is its cell type?
Epidermis
Stratified cellular epithelium
What layer is beneath the epidermis and what cell type is it?
Dermis
Connective tissue
What skin layer is described - Ectoderm cells form single layer periderm, gradual increase in layers of cells and periderm cells cast off?
Epidermis
What is the dermis formed from?
Mesoderm below the ectoderm
What are pigment producing cells from neural crest?
Melanocytes
What are developmental growth patterns of skin - not following vessels, nerves or lymphatics?
Blaschko’s lines
Name four skin appendages?
- Nail
- Hair
- Glands
- Mucosae
What makes up skin and is predominantly fat?
Sub-cutis
Does the skin consist of dermo-epidermal junctions?
Yes
What is stratified squamosu epithelium, 1.5mm thick?
Epidermis
What is 95% of the epidermis?
Keratinocytes
What do keratinocytes contain?
Structural keratins
What are three other cell types in the epidermis?
Melanocytes (basal and suprabasal) Langerhans cells (suprabasal) Merkel cells (basal)
What are the four epidermal cell layers?
- Keratin layer
- Granular layer
- Prickle cell layer
- Basal layer
What three factors control regulation of epidermal turnover?
Growth factors
Cell death
Hormones
Name two situations where regulation of epidermal turnover is lost?
Skin cancer and psoriasis
What takes 28 days and involves keratinocytes migrating from basement membrane as well as continuous regeneration of epidermis?
Differentiation
What layer is usually one cell thick and small cuboidal?
Basal layer
The basal layer is highly metabolically active and has lots of what substance?
Intermediate filaments (keratin)
What layer has larger polyhedral cells?
Prickle cell layer
In the prickle cell layer there are lots of desmosomes - what connects to them?
Intermediate filaments
What layers does the granular layer consist of?
2-3 layers of flatter cells
What layer contains large keratohyalin granules?
Granular layer
What contains structural filaggrin and involucrin proteins and is present in the granular layer?
Large keratohyalin granules
What layer has odland bodies, high lipid content, cell nuclei lost and is the origin of “cornified envelope”?
Granular layer
What are overlapping non-nucleated cell remnants called and what layer do they occur in?
Corneocytes
Keratin layer
What makes up 80% of the keratin layer?
Keratin and filaggrin
What do lamellar granules release in the keratin layer?
Lipids
What layer is a tight waterproof barrier?
Keratin layer
What mucosa is present in lacrimal glands, eye lashes and sebaceous glands?
Ocular mucosa
Where do melanocytes migrate to in the first 3 months of foetal development?
From the epidermis to neural crest
What are pigment producing dendritic cells?
Melanocytes
What are the organelles in melanocytes called?
Melanosomes
What are the two types of melanin pigment made from tyrosine by melanocytes?
- Eumelanin (brown or black)
2. Phaeomelanin (red or yellow)
Does melanin absorb light?
Yes - neutral density filter
How are full melanosomes transferred to adjacent keratinocytes?
Via desmosomes
What do melanocytes form a protective cap over?
Nucleus
What represents an autoimmune disease with loss of melanocytes?
Vitiligo
In what disorder is there a genetic partial loss of pigment production?
Albinism
What disorder involves melanin stimulating hormone produced in excess by the pituitary gland?
Neslons Syndrome
What is a tumour of the melanocyte cell line?
Malignant melanoma
What cells come from mesenchymal origin - bone marrow?
Langerhans cells
What level are Langerhans cells found in?
Prickle cell level in epidermis - also found in dermis and lymph nodes
What cells found in the prickle cell level are antigen presenting cells?
Langerhans cells
What cells are basal, between keratinocytes and nerve fibres and act as mechanoreceptors?
Merkel cells
What type of infection is merkel cell cancer caused by?
Viral
What appendages have adjacent sebaceous glands?
Hair follicles
Hair pigmentation occurs via what?
Melanocytes above dermal papilla
What are the three phases of hair follicles growth?
Anagen - growing
Catagen - involuting
Telogen - resting
Name a hormone that influences hair growth?
Thyroxine
What are the three types of hair follicles?
Lanugo (in utero), vellus, terminal
What phase of hair follicles growth is the shedding phase?
Telogen
In humans what is the telogen phase?
Asynchronus
What is the interface between the epidermis and dermis called? It also has a key role in epithelial-mesenchymal interactions including support, anchorage, adhesion, growth and differentiation of epidermal cells. Also semi-permeable membrane acting as a barrier and filter.
Dermo-epidermal junction
What are inherited skin fragility diseases of the DEJ due to?
Mutation in one of the proteins in the DEJ.
Name three acquired (auto-antibodies to proteins in DEJ) diseases of the DEJ.
- Pemphigus
- Pemphigoid
- Dermatitis herpetiformis
Name two inherited skin fragility.
Epidermolysis Bullosa simplex
Epidermolysis Bullosa dystrophica
Name an acquired blistering disorder?
Bullous pemphigoid
What are these cells components of: mainly fibroblasts, macrophages, mast cells, lymphocytes, Langerhans cells?
Dermis
What two fibres make up the dermis?
Collagen and elastin
Is ground substance present in the dermis?
Yes
What do fibroblasts secrete?
Collagen
Name some cells in the dermis which antigen present?
Langerhans cells
Name the cells in the dermis which are chemical messengers?
Mast cells
What substance do mucopolysaccharides and glycosaminoglycans make up in the dermis?
Ground substance
Are the blood vessels in horizontal or vertical plexi?
Horizontal
Name a condition caused by localised overgrowth of blood vessels?
Port wine stain “stone marks” (capillary or cavernous haemangiomas)
What do smaller non-contractile lymphatic vessels lead to?
Larger contractile lymphatic trunks
What gives continuous drainage of plasma proteins, extravasated cells and excess interstitial fluid?
Lymphatic vessels
What do the special receptors pacinian and Meissners corpuscles detect?
Pressure and vibration
What are the three types of skin glands?
- Eccrine gland
- Sebaceous gland
- Apocrine gland
Where are the largest sebaceous glands present?
On the face and chest
What four things make up sebum?
Squalene, wax esters, triglycerides and free fatty acids
What produces sebum?
Sebaceous glands
Give two functions of sebaceous glands?
Controls moisture loss and protects against bacterial and fungal infection
What occurs as a result of increased sebum, blocked ducts and bacterial activity?
Acne
What do apocrine sweat glands develop as a part of?
Pilosebaceous unit
In what two locations are apocrine sweat glands found?
Axillae and perineum