L19: Skin structure and function Flashcards
What is the general structure of the skin?
Epidermis
Dermis
Hypodermis
What are the key features of each layer?
Epidermis→ superficial, stratified squamous kertinised epithelium, avascular, split into layers
Dermis→ Deeper, provides support for epidermis, contains connective tissue element, part of skin appendages, nervous structures and vascaulature
Hypodermis→loose connective tissue with adipose tissue, sweat and sebaceous glands and larger blood vessels
What is the function of the skin?
- Protection against microbial attack
- Prevention of fluid loss
- Temperature regulation
- Fine control of excretion and absorption
- Regeneration of skin tissue
- Sensation (fine touch and grip control)
What is the main structure of the hypodermis?
Fat cells
Loose connective tissue→ fibroblasts, macrophages, mast cells and fibres
Adipose tissue→ neurovascular bundle and lymphocytes
How does the thickness of the hypodermis vary between males and females?
Males→ thickest abdomen and shoulder
Females→ thickest in hips, thighs and buttocks
Both thick in palms of hands for cushioning
Thinning in ageing causes wrinkles to form and hypothermia
What are the functions of the hypodermis?
- Provides energy store→ provides fuel for heat for cells under hypodermis
- Insulation for heat generation
- Shock absorber→ cushioning impact
- Connects skin to underlying muscle and bone
- Makes hormones
What is the structure of the dermis?
Between the hypodermis and epidermis
3 layers
- Papillary layer→ hold epidermis in place
- Reticular layer→ dense loose connective tissue
- Dermal papillae layer→ interdigitating between epidermal ridges
What are the functions of the dermis?
Contains hairs and sweat glands → thermoregulation
Contains sensory structures→ mechanoreceptors
Gives structure to skin
What is the structure of the epidermis?
Thin and thick skin
Thin→ four layer
Thick→ five layers
Laterally held together by adherens junction
Layers held together by desmosomes
Some nerve terminal found in these layers
NO blood vessels
What is the function of the epidermis?
- Prevents water loss
- Absorbs water
- Prevent entry of pathogens
- Synthesis keratin
- Prevents underlying abrasion (loss of tissue)
What are the different layers of the skin?
Come Lets Get Sun Burnt Stratum Corneum (horny cell layer) Stratum Lucidum (transparent layer) Stratum Granulsum (granular layer) Stratum Spinosum (spinous layer) Stratum Basale (basal cell layer)
What is the stratum corneum?
Outermost cell layer
Made of squames (dead keratinocytes)
Thick on palms and soles of feet- prone to injury
Continuously shed
What is the stratum lucidum?
Transparent cell layer
Only on palms and soles of feet
What is the stratum granulosum?
Stratified squamous epithelium
Lamellar granules (filament associated proteins that assemble keratin fibrils and secrete them)
Tonofibrils (bundles of keratin filaments and keratohyalin granules) made by lamella bodies
What is the stratum spinous?
Cuboidal epithelium arranged in 3 layers (held together by desmosome)
Producers of lamellar bodies (keratin factories)
Cells contain golgi apparatus→ allowing proteins to be modified before secretion