Dermatology 1 Flashcards by Pavan Khatkar

How is the skin embryologically formed?

Juxtaposition of the ectoderm (epidermis) and the mesoderm (dermis)

How well did you know this?

Not at all

Perfectly

What happens in week 4 of development?

Epidermis forms from a single basal layer of cuboidal cells

How well did you know this?

Not at all

Perfectly

What happens in week 5 of development?

Periderm develops along with the Vernix caseosa

How well did you know this?

Not at all

Perfectly

What happens in week 11 of development?

Basal layer proliferates to from 4 more superficial strata

How well did you know this?

Not at all

Perfectly

What happens in week 9-13 of development?

Hair follicles + lanugo hair form in the stratum germinatium

How well did you know this?

Not at all

Perfectly

How do we get the formation of melanocytes?

Derived from neural crest to melanobasts and then differentiation and dorsal migration to epidermis, dermis and hair follicles to form melanocytes

How well did you know this?

Not at all

Perfectly

When do melanocytes form?

Week 12-13

How well did you know this?

Not at all

Perfectly

What else aside from melanocytes can melanoblasts form?

Melanocyte stem cells for replenishment

How well did you know this?

Not at all

Perfectly

How are melanocytes regulated?

MC1R gene (Melanocortin 1 receptor) - regulates the quantity and quality of melanin produced

How well did you know this?

Not at all

Perfectly

How does ACTH affect MC1R?

Upregulates MC1R expression

How well did you know this?

Not at all

Perfectly

How does a-MSH affect MC1R?

alpha melanocyte stimulating hormone activates MC1R and stimulates a melanogenic cascade and eumelanin production

How well did you know this?

Not at all

Perfectly

How does Agouti Signalling protein affect MC1R?

Antagonist - reverse the effects and elicits pheomelanin production

How well did you know this?

Not at all

Perfectly

How does UV affect melanocytes?

Exposure leads to increase in MITF. expression and downstream melanogenic proteins. UV exposure also increases PAR2 in keratinocytes to increase melanosome uptake and distribution in keratinocytes

How well did you know this?

Not at all

Perfectly

What is the epidermis made up of?

Keratinocytes

How well did you know this?

Not at all

Perfectly

Where does division in the epidermis take place?

Basal layer

How well did you know this?

Not at all

Perfectly

What are the layers of the epidermis?

Basal layer
Stratum spinosum
Stratum granulosum
Stratum corneum

How well did you know this?

Not at all

Perfectly

What layer of epidermic may not always be present?

Stratum lucidum - present in between granular and corneum

How well did you know this?

Not at all

Perfectly

What is different about the startup corneum and other epidermal layers?

No nuclei or organelles

How well did you know this?

Not at all

Perfectly

How long does the process of cells progressing from basal layer to corner layer take?

30 days - alters with skin disorders

How well did you know this?

Not at all

Perfectly

What does the keratinocyte cytoskeleton compose of?

Actin with microfilaments
Tubulin with microtubules
Intermediate keratin filaments

How well did you know this?

Not at all

Perfectly

What is the role of keratins?

Structure
Cell signalling 
Stress response
Apoptosis 
Wound healing

How well did you know this?

Not at all

Perfectly

What intercellular junctions are found between keratinocytes?

Tight junction
Adherens
Gap junction
Desmosomes

How well did you know this?

Not at all

Perfectly

What is the role of desmosomes?

Anchor keratin and bridge adjacent keratinocytes. Have a role in allowing the cell to withstand trauma

How well did you know this?

Not at all

Perfectly

What is the role of gap junctions?

Intercellular channels
Connect adjacent keratinocyte cytoplasms
Essential for cell synchronisation, differentiation, growth and metabolic coordination

How well did you know this?

Not at all

Perfectly

What is the role of adherens?

Transmembrane | Engage with actin skeleton

What is the role of tight junctions?

Barrier integrity | Cell polarity

What other cells do we find in the epidermis?

Melanocytes Langerhans cells Merkel cells Mast cells

What are melanocytes?

Dendritic cells that distribute melanin in melanosomes to keratinocytes

What are langerhans cells?

Dendritic, antigen presenting cells

What are Merkel cells?

Mechanosensory receptors

What are mast cells?

Immune response

What is the basement membrane?

Dermal-epidermal junction

What is the basement membrane made up of?

Proteins and glycoproteins (collagen IV and VII), laminins and integrins

What is the role of the basement membrane?

Cell adhesion | Cell migration

What is the role of the dermis?

Supporting (ECM) that provides resilience

What are the main 2 layers of the dermis?

Papillary | Reticular

Describe the papillary dermis

Superficial Loose connective tissue Vascular

Describe the reticular dermis

Deep Dense connective tissue Forms the bulk of the dermis

What is the dermis made up of?

Proteins Glycoproteins Ground substance

What proteins make up the dermis?

Collagen (I and III) -80% | Elastic fibres elastin and fibrillin - 3%

What glycoproteins make up the dermis?

Fibronectin Fibulin Integrins

What is the role of glycoproteins in the dermis?

Facilitate cell adhesion and motility

What ground substances are found in the dermis?

Glycosaminoglycan | Proteoglycan

Where are ground substances found in the dermis?

Found between dermal collagen and elastic tissue

What is the primary cell of the dermis?

Fibroblasts

What other cells are found in the dermis?

Histiocytes, mast cells, neutrophils, lymphocytes, dermal dendritic cells.

What types of blood supply do we have to the skin?

We have deep and superficial blood supply to make up 3 different vascular plexuses

Where is the vascular plexus/blood supply found?

Subcutaneous plexus is found in the hypodermis Reticular plexus is found in the reticular dermis Superficial plexus found in papillary dermis Does not cross into the dermis.

What innervation do we have in the skin?

Sensory and autonomic

What type of autonomic innervation do we have in the skin?

Cholinergic: eccrine seat glands Adrenergic: eccrine and apocrine

What areas do we find the most highly innervated at the skin?

Extremities, face and genitalia

What types of afferent nerves do we have?

Corpuscles and free nerve endings

What are corpuscular afferent nerves?

Encapsulated receptors restricted to dermis

What are free afferent nerves?

Non encapsulated crossing into epidermis

Describe meissner's corpuscle

Encapsulated unmyelinated mechanoreceptor found in the papillary dermis. It's responsible for sensing light touch (+ slow vibration) and is found in most thick hairless skin e.g. the finger tips.

Describe Ruffini's corpuscle

``` Slow acting mechanoreceptor Spindle shaped Deeper in dermis Found in finger nails Monitors skin stretching and slippage of objects ```

Describe Pacinian (lamellar) corpuscle

Encapsulated mechanoreceptor Rapid acting Egg shaped Senses deep pressure and vibration

Describe Merkel Cells

``` Non-encapsulated Oval shaped Mechanoreceptor Found in epidermis Detects light or sustained touch and pressure ```

Where do we find modified epidermal cells?

Stratum basal above the basement membrane. Most commonly found in the finger tips however also in the palms, soles, oral and genital mucosa.

What does the skin microbiome consist of?

Viruses Fungi Bacteria Composition varies with environment

What are the main bacteria we find in the microbiome of skin?

Actinobacteria Firmicutes Bacteroidetes Proteobacteria

What is the role of the skin microbiome?

Immune modulation and epithelial health | Disease

What are the 6 main functions of the skin?

``` Immunological barrier Physical barrier Thermoregulators Sensation Metabolism Aethetic appearance ```

How does the skin act as an immune barrier?

Langerhans cells act as sentinel cells and contribute to immune tolerance. However they extend their dendritic processes through intercellular junctions to monitor the external environment

What happens when langerhans cells detect no threat?

They will promote expansion and activation of Treg cells.

What happens when langerhans cells detect PAMPs?

This means they sense danger therefore rapidly activate the innate immune response and induce and adaptive immune response with specific T cells.

What other cells are involved in immune defence of the skin?

Tissue resident T cells, macrophages, dendritic cells also carry out immune surveillance and provide rapid backup tif the epidermis is breached

How does the skin act as a physical barrier?

Stratum corneum and cornfield cell envelope restrict water/protein loss

How might we get visceral problems from extensive skin disease?

Loss of water and protein may be attributed to renal failure/ high output cardiac failure.

What is the role of sub-cutaneous fat in the skin and its physical barrier?

Cushion trauma.

Explain thermoregulation in the skin

Vasodilation/constriction of deep or superficial plexuses to regulate heat loss Eccrine sweat glands also provide a cooling effect Role in fluid balance

Explain metabolic functions of the skin?

Vitamin D synthesis | Subcutaneous fat acts as a calorie reserve and releases leptin to act on the hypothalamus and stimulate satiety.

What is the role of basal keratinocytes with melanin in the physical barrier of the skin?

Protect against UV induced damage.

Dermatology 1 Flashcards

(73 cards)