Integumentary system Flashcards
What is the integumentary system?
The skin and its accessory organs
What is the structure of the skin?
Epidermis
Dermis
Hypodermis
What is the function of the hypodermis?
Anchors the dermis to the epidermis
What are the 2 zones of the dermis?
Papillary layer
Reticular layer
Structure and function of papillary layer?
Thin region of loose connective tissue (areolar)
Allows mobility of leukocytes, mast and macrophage cells
Structure and function of the reticular layer
Thick layer of dense irregular connective tissue
Adipocyte clusters
Stretches skin in weight gain
Function of a fibroblast
Produces laminin and fibronectin
What are the accessory organs of the dermis
Hair
Nails
Oil
Sweat glands
What are some specialisations of the dermis?
Rich layer of blood and lymphatic vessels
Nerve endings
Arteriovenous anastomoses
What is an arteriovenous anastomoses?
Direct connections between small arteries and small veins
Aids in thermoregulation
Structure of the dermal-epidermal boundary?
Wavy boundary of finger like projections
Dermal papillae and epidermal ridges
What do tall dermal papillae facilitate?
Nerve fibres reaching close to the dermal epidermal boundary in highly sensitive areas
What type of epithelium is the epidermis?
A keratinised stratified squamous
Name the 4 layers of thin skin
Stratum Basale
Stratum spinosum
Stratum granulosum
Stratum corneum
Where is ‘thick’ skin found?
Palms and feet
Name the 5 layers of thick skin
Stratum corneum
Stratum lucidium
Stratum granulosum
Stratum spinosum
Stratum Basale
What is the self-regeneration time for the epidermis?
2-4 weeks
What cells does the stratum basale contain?
Keratinocytes
Melanocytes
Tactile/Merkel cells
Where are keratinocytes mitotically active?
Basement membrane
What pigment does pheomelanin give off?
Red soluble pigment
What pigment does eumelanin give off?
Brown insoluble pigment
Function of tactile/Merkel cells
Connect to sensory nerves to give sense of touch
What are dermal papillae interdigitated with?
Epidermal rete ridges
At the junction of tissues
What is melanin?
UV absorbent antioxidant
Radical scavenge
What does melanin pigmentation depend on?
Carotene pigments
Amount of blood and haemoglobin
Where are carotene pigments found?
In subcutaneous fat
Stratum corneum
What are melanosomes phagocytosed by?
Keratinocytes to surround the nucleus
What is the thickest ‘thin’ skin layer?
Stratum spinosum
What is the thickest ‘thick’ skin layer?
Stratum corneum
What are 3 specialisations of the stratum spinosum?
Produce keratin filaments causing cells to flatten
The deepest cells are mitotic, pushed upwards and cease to divide
Tight junctions ensure water retention
What are keratinocytes linked to in stratum spinosum?
Desmosomes
What are keratohyalin granules?
Dark staining
Bind to cytoskeleton and are converted keratin
How many layers is the stratum granulosum?
3-5 layers of flat keratinocytes
What stage of the cell cycle is stratum granulosum in?
Post mitotic
Specialisation of stratum granulosum
Produce glycolipid filled vesicles which sit between the stratum spinosum for waterproofing
What is the name for conversion of keratohyalin to keratin ?
Transglutaminases
What is the structure of the stratum lucidium?
2-3 cell layers
What cells are found in stratum lucidium?
Dead keratinocytes
Cytoplasmic granules of eleidin
What are cytoplasmic granules of eleidin?
A product of keratohylain
Structure of stratum corneum
15-30 layers
Upper layer is terminally differentiated with dead keratinocytes
Specialisation of the stratum corneum
Has a cornified envelope
Resistant to abrasion, penetration and water loss
How is an iron deficiency displayed in nails?
Flat or concaved
How is long term hypoxemia displayed in nails?
Clubbed
Structure of nails
Dead scaly cells densely packed with hard keratin fibres
Derived from stratum corneum
Structure of hair
Slender filament of keratinised cells from follicle
What are the 3 stages of hair?
Lanugo
Vellus
Terminal
What are the 3 layers of the hair follicle?
Medulla
Cortex
Cuticle
Name the 5 types of skin glands
Merocrine
Apocrine
Sebaceous
Ceruminous
Mammary (female only)
Function of merocrine gland
Sweat gland
Secretes watery perspiration to skin
Associated with myoepithelial cells
Function of Apocrine cells
Sweat glands
Scent glands responding to stress and sexual stimulation
Structure of physical barrier
Cross linked keratin layer on a scaffold of keratinocytes
Describe the biochemical barrier
Slightly acidic
Contains bacteriocidal agents
What bactericidal agents are in the biochemical barrier?
Saturated and unsaturated fatty acids (inhibit growth)
Lysozyme (cleaves cross links in bacterial cell wall)
Describe the immunological layer
Langerhans cells (in stratum spinosum) take up and process antigens.
They migrate to lymph nodes and present antigens to the skin lymphocytes which circulate to secondary lymphoid organs.
Where are the warm and cold receptors found?
The preoptic anterior hypothalamus
Where does counter current heat exchange occur?
Between arterial and venous blood in the dermis
Blood flow at 250ml/min dissipates heat at …
80kcal/hr
