Basic Science Flashcards
What is used to rank how much melanin pigment is produced by the skin
Fitzpatrick scale
Fitzpatrick scale
- Skin type 1 features
- Exposure to sunlight
Features: v pale white skin, blue/green eyes
Sunlight exposure: never tan, always burn
Fitzpatrick scale
- Skin type 2 features
- Exposure to sunlight
Features: pale white/fair skin
Sunlight exposure: rarely tans, burn easily
Fitzpatrick scale
- Skin type 3 features
- Exposure to sunlight
Features: darker white skin
Sunlight exposure: tans uniformly, burn turns to tan
Fitzpatrick scale
- Skin type 4 features
- Exposure to sunlight
Skin features: light brown skin
Sunlight Exposure: tans easily, burns minimally
Fitzpatrick scale
- Skin type 5 features
- Exposure to sunlight
Features: brown skin
Sunlight exposure: tans v easily, very rarely burns
Fitzpatrick scale
- Skin type 6 features
- Exposure to sunlight
Features: dark brown/black skin
Sunlight exposure: never burns
How many main layers of skin + name them (from superficial to deep)
3 main layers
1. Epidermis
2. Dermis
3. Hypodermis (subcutaneous layer)
Epidermis
- type of epithelium it is made up of?
- is it vascular or avascular
- made up of keratinised stratified squamous epithelium
- completely avascular
How many layers in epidermis + name them (from deep to superficial)
4 or 5 depending on location
- Basal layer (Stratum basale)
- Prickle cell layer (Stratum spinosum)
- Granular cell layer (stratum granulosum)
- Keratin later (stratum corneum)
5th layer in palm of hands + soles of feet called the stratum lucidum (in between corneum and granulosum)
Hypodermis contents
Adipocytes
Nerves
Blood vessels
What is the pilosebaceous unit
Structure consisting of:
- the hair
- hair follicle
- arrector pilli muscle
- sebaceous gland
Normal hair cycle
- how many phases
- name the phases
3 phases
1. Anagen (growing)
2.Catagen (involuting)
3. Telogen (resting)
How long does anagen phase last
3-5 years
How long does involution phase last
2 weeks
How long does telogen phase last
3 months
What happens during telogen phase of hair growth
Hair remains in the follicle but doesn’t grow anymore
What rate does hair grow
1cm/month
3 types of skin glands
- sebaceous glands
- apocrine glands
- eccrine glands
Eccrine glands
- what do they do
- where are they found
- what are they under control of
- regulate body temp by secreting salty solution that evaporates on skin surface causing cooling
-found on entire skin except lips and genitals (most commonly found on palms and soles) - sympathetic nervous system
Apocrine glands
- what do they do
- where do they develop
- produce oily fluid that becomes colonised by anaerobic bacteria causing body odour
- as part of pilosebaceous unit in axillary and perineal regions (nipples and genitals)
Sebaceous Glands
- where found
- what do they do
- what type of glands are they
- all over body except palms, soles and dorsum of feet (mostly concentrated in face and scalp)
- produce + secrete sebum to protect skin from dehydration + have antibacterial properties
- holocrine glands
EMBRYO
What is the dermis derived from
The mesoderm
EMBRYO
What forms the dermis of the back
Paraxial mesoderm
EMBRYO
What forms the dermis of the face and neck
Neural crest cells
EMBRYO
What forms the dermis of the body wall and limbs (minus the face neck and back)
Lateral plate mesoderm
EMBRYO
What are Blaschko Lines
Lines that cover surface of body that represent natural migration of epidermal cells during embryological development
EMBRYO
- When does the epidermis develop during gestation?
- What does it develop from?
- What is it called at this time?
- Near end of week 4
- Develops from single layer of surface ectoderm
- Called basal layer
how do terminal parts of sweat ducts appear in histology
Helical structures
When do apocrine glands develop and what do they open into
at puberty
open into hair follicles
Function of arrector pili
Pull hair perpendicular to skin during cold/fright (goose bumps)
Purpose of connective tissue in dermis
Provide tensile strength + elastic qualities of skin
NERVOUS TISSUE
Meissner’s corpuscles
- Where are they found
- What are they for
- Found just below epidermis in dermis + abundant in tactile areas of fingers and toes
- Tactile sensation
NERVOUS TISSUE
Pacinian corpuscles
- What are they for
- Where are they found
- Deep pressure
- Found deep in dermis, often seen in finger pulp sections
NERVOUS TISSUE
Free Nerve Endings
- Where found
- What for
- Basal layer of epidermis
- Pain
Hair structure
- Central medulla
- Cortex
- Outer cuticle
- Internal root sheath
- External root sheath
- Connective tissue sheath
HAIR
Central medulla of hair follicle contains what
soft keratin
HAIR
outer cortex and cuticle of hair follicle contains what
hard keratin
Hair bulb
- Where is it found
- What does it contain
- Found at base of follicle
- Contains hair matrix + dermal papilla (Bulge at base)
HAIR
Papilla contains
Multiple vascular channels
HAIR
Matrix region contains
Keratin producing cells
NAILS
Structure
- Nail plate (Sits on nail bed)
- Matrix (cells divide and then produce hard keratin)
- Cuticle (extension of skin fold covering nail root)
- Hyponychium (Secures free nail edge)
What is primary intention wound healing
edges are approximated by stitches causing rapid healing
What is secondary intention wound healing
3 stages of healing
1. Inflammation
2. Proliferation + Tissue remodelling
3.Tissue Remodelling
Explain secondary intention healing stage 1
- Platelets from initial clot + release inflam mediators
- Leucocytes debride wound (they phagotise bacteria and capture debris)
- Inflammation decreases as keratinocyte proliferation + new tissue formation becomes predominant
Explain secondary intention healing stage 2
- Cells divide to re-epitheliase wound surface
- Granulation tissue formation is formulated
- Firboblasts lay down matrix + contract wound (fibroplasia)
- Endothelial cells develop into new blood vessels (angiogenesis)
Explain secondary intention healing stage 3
- New tissue is converted into mature scare tissue over months
- Fibroblasts lay down collagen to improve the tensile strength of the scar + restore normal dermal matrix
What are burns
Thermal injury to skin
Classifications of burns
1st degree => Epidermis only
2nd degree/Partial thickness => epidermis + dermis
3rd degree/full thickness=> extends beyond dermis
Deep burns presentation
White or black + charred
Dry + numb
Superficial burn presentation
Erythematous
Wet
Extremely painful
What is a chronic wound
Those present >6 weeks
Common presentation of chronic wound
SURFACE SLOUGH
- Mixture of dead cells, polymorphs + bacteria that appears yellow/green
- Adherent to underlying tissue
Does surface slough help or inhibit wound healing + what is done with it
Inhibits so should be removed chemically, physical or larval therapy
Pressure sore development stages
- Skin is unbroken but has pink/redish area that could be tender, itchy or painful
- Skin is red, swollen + painful. Broken/intact blisters may be present. Upper layers of skin start to die
- Sore broken thru skin + wound extends down to deeper layers of skin tissue. Crater-like ulcers are present and wound is prone to infection
- Sore extends past skin into fat, muscle + bone tissue. Blackened dead tissue (eschar) can be seen in deep open wounds
Which condition is spongiosis commonly seen in
acute dermatitis
histological signs of psoriasis
- parakeratosis (more purple nuclei seen keratin layer)
- micro-abscesses (accumulation of inflammatory cells in upper epidermis
- thicker + longer rete pegs
SKIN functions
- prevents water loss
- Prevents entry of unwanted substances
- Metabolism + detoxification
- Immune defence
- Sociosexual/Sensory functions
Layers of dermis
- Papillary Dermis - superficial layer made up of highly vascular loose connective tissue
- reticular dermis - deep thick layer of dense connective tissue
Components of dermis not done
Fibres - collagen (gives skin touch properties) + elastin (elastic properties)
Ground substance (
Are blaschko lines visible
Normal population - no
Some conditions
EMBRYO
- Walk me through epidermis development
- week 4: single layer of cuboidal shaped basal layer develops from single layer surface of ectoderm
- week 5: now a squamous non-keratinised layer of cuboidal cells called the periderm (or epitrichium) forms over the basal layer
- second half of gestation: desquamitisation then casting of cells in periderm causing vernix caseosa to be formed
- by 20 weeks gestation: remaining basal layer develops till it becomes stratum basale which proliferates + differentiates until epidermis splits into its 4 layers
EMBRYO
What is vernis caseosa
Substance that coats the foetus to protect it from both amniotic fluid + bacteria within the birth canal as it descends during labour
- What is the dermoepidermal junction
- What does the dermoepidermal junction do
- semipermeable membrane that acts as a barrier to invading microorganisms
- important in support, anchor, adhesion , growth and differentiation of basal cells
Cells of epidermis
- Keratinocytes
- Melanocytes
- Merkel Cells
- Langerhans Cells
