lecture 1 - anatomy of the skin 1 Flashcards
What does the skin protect underlying tissues and organs from?
Impact, abrasion, fluid loss and chemical attack
What glands in the skin excrete salts, water and organic wastes?
Integumentary glands.
What are the 4 types of integumentary glands?
sweat, sebaceous, ceruminous, mammary
What are integumentary glands?
Exocrine glands of the skin/body’s that secrete salts, water and organic wastes
How does the skin maintain body temperature?
Insulation or evaporative cooling
How does the skin protect against ultraviolet radiation?
By producing melanin
What is the function of keratin in skin?
Protein that protects against abrasion and repels water
How is the skin involved in calcium homeostasis?
It is involved in the synthesis of vitamin D3 - which is involved in regulation of the uptake of Calcium by the body
How does the skin store lipids?
In apidocytes that make up the hypodermis
What 4 types of tissue make up skin?
Epithelial, connective, muscle, nervous
What is the dominant tissue type in the epidermis of the skin?
Epithelial
What are the 3 primary layers of the skin?
Epidermis, dermis, hypodermis
What is the outer layer of the skin?
Epidermis
What is the middle layer of the skin called?
Dermis
What is the innermost layer of the skin called?
The hypodermis
What is the structure of the epidermis?
Avascular, Stratified barrier made up of keratinocytes.
What is the structure of the dermis?
Connective tissue layer with collagen and elastin protein fibres for strength and elasticity, and is vascular. Contains secondary structures, such as hair follicles, glands, nerves
What is the structure of the hypodermis?
Adipose/fat tissue from adipocytes
What 2 layers make up the cutaneous part of the skin?
Epidermis and dermis
What layer makes up the subcutaneous layer of the skin?
Hypodermis
What are the 2 types of epithelial tissue cellular structure?
Simple and stratified
What are the 3 forms of simple or stratified epithelia?
Squamous, cuboidal, columnar
What is simple epithelia?
Epithelial tissue consisting of a single layer of epithelial cells.
What is stratified epithelia?
Epithelial tissue consisting of a stacked layers of epithelial cells.
What is the shape of squamous epithelial cells?
Flat and wide
What is the type of epithelial tissue that dominates the epidermis?
Stratified squamous epithelium
What are the layers of the epidermis (4)?
Stratum corneum, Stratum granulosum, stratum spinosum, stratum basale
What is the alternative name for the stratum corneum?
Horny layer
What is the alternative name for the stratum granulosum?
granular layer
What is the alternative name for the stratum spinosum?
Spinous, spiny or prickly layer
What is the structure of the stratum corneum?
Upper layer of the epidermis made of dead, dried out hard cells with no nuclei. Contains keratin.
What is the structure of the stratum granulosum?
2nd most superficial layer of the epidermis. Contains granules that promote dehydration of the cells and keratin fibre cross linking.
What is the structure of the stratum spinosum?
Layers of cells that become increasingly squamous shaped as they move upwards through the layer. Cells linked by intercellular bridges called desmosomes.
What is the structure of the stratum basale?
Made up of columnar regenerative/stem cells that divide to give daughter cells that migrate upwards to replenish the layer above
What are desmosomes in terms of the skin?
Junctions that anchor neighbouring cells in the epidermis
What are hemidesmosomes in terms of the skin?
Junctions that anchor the stratum basale (of the epidermis) to the dermis
What is the difference between desmosomes and hemidesmosomes, in the skin?
Demsosomes anchor neighbouring cells within the epidermis, while hemidesmosomes anchor the stratum basale of the epidermis to the underlying dermis.
Where is thick skin found?
On the palms of the hands and soles of the feet
Does thick or thin skin have hair?
Thin
What is the extra epidermal layer of thick skin?
Stratum lucidum
Where is the stratum lucidum of thick skin located?
Below the stratum corneum
Is the dermis shed?
No
What are the 2 layers of the dermis?
Papillary and reticular
What features are common to both the papillary and reticular layers of the dermis?
Blood vessels, lymphatics, sensory nerve fibres and accessory structures.
What is the structure and function of the papillary layer of the dermis?
Highly vascularised to provide nourishment to the epidermis above
What is the structure and function of the reticular layer of the dermis?
Mesh-like structure of collagen and elastin fibres which provides strength to the skin
What are plexuses of the dermis?
Networks of blood vessels
What are the 2 plexuses of the dermis?
Cutaneous plexus and Sub-papillary plexus.
What is the structure of the cutaneous plexus of the dermis?
Network of blood vessels at the junction of the dermis and hypodermis.
What is the function of the cutaneous plexus of the dermis?
Supplies the hypodermis and deeper dermis with blood, including the capillaries for hair follicles and sweat glands.
What is the structure of the sub-papillary plexus of the dermis?
Branches from the cutaneous plexus and lies underneath the papillary layer of the dermis
What is the function of the sub-papillary plexus of the dermis?
Provides oxygen and nutrients to the upper dermis and epidermis.
What is the hypodermis?
The subcutaneous layer of the skin, made predominantly of subcutaneous fat
What is the dominant cell type in the hypodermis, and what do they make?
Adipocytes, which produce subcutaneous fat.
What is the function of subcutaneous fat?
Stores energy as fat and provides insulation for thermoregulation
What layer of the skin do subcutaneous injections inject into, and why?
Hypodermis, which has limited vascularity
What are the 3 types of burns?
1st, 2nd and 3rd degree
What layers of the skin are damaged by 1st degree burns?
Outer layers of the epidermis (superficial)
What layers of the skin are damaged by 2nd degree burns?
Epidermis and varying amounts of the dermis
What layers of the skin are damaged by 3rd degree burns?
Epidermis, dermis and hypodermis. Can even extend down into muscle/bone
What are the characteristics of 1st degree burns?
Red/pink colour, dry, painful, usually no blistering.
In 1st degree burns, is the water and bacterial barrier intact?
Yes
How long does it take for 1st degree burns to heal approximately?
3-10 days
What are the characteristics of normal 2nd degree burns?
Painful, moist, red, blistered.
How long do normal 2nd degree burns take to heal?
1-2 weeks approx.
How long do deeper 2nd degree burns take to heal?
Approximately a month
What are the characteristics of deeper 2nd degree burns?
May include white, waxy areas. Some loss of sensation and scarring
What are the 2 types of 2nd degree burns?
Normal and deep
What are the characteristics of 3rd degree burns?
Varied colour - waxy white to red to black
Why do 3rd degree burns have little pain?
Nerve endings in the skin are destroyed, resulting a lack of sensation.
What is treatment for severe 3rd degree burns?
Skin grafts
How long does it take for 3rd degree burns to heal?
Months to years, with permanent scarring
