Flashcards in The Skin Deck (76)
What is the heaviest single organ of the body and what percentage of the total body weight does it constitute for?
The skin makes up 16% of the total body weight
What are the four major functions of the skin?
4. Metabolic functions
What does the skin protect against?
Against UV, mechanical and chemical insults, microorganisms and dehydration
How does the skin play a thermoregulatory role?
Due to the hair and deep fatty tissue
What metabolic functions does the skin play?
Tryglycerides (fat) stored within deep tissue and vitamin D is synthesised in this organ
What are the four layers of the skin?
2. Basement membrane
4. Subcutis (hypodermis)
Does the epidermis layer of the skin have blood vessels?
No, it is avascular - nourished by diffusion from the dermis
List four types of cells present in the epidermal layer of the skin
Keratinocytes, melanocytes, Langerhans cells, Merkel cells
What is the main constituent in terms of cells of the epidermal layer of the skin?
Keratinocytes which make up around 95% of the epidermis
What are rete ridges?
They are epidermal thickenings that extend downward between dermal papillae
What is the basement membrane in the skin?
The multilayered structure forming the dermoepidermal junction
What is the dermis layer of the skin?
The area of supportive connective tissue between the epidermis and the underlying subcutis (hypodermis)
List six structures the dermis layer of the skin contains
1. sweat glands
2. hair roots
3. Nervous cells
6. Lymph vessels
What is the subcutis (hypodermis)?
The layer of loose connective tissue and fat beneath the dermis
What type of epithelium cell makes up the epidermis layer of the skin?
Keratinising stratified squamous epithelium
What is the function of the keratinising stratified squamous epithelium cells that make up the epidermis layer of the skin?
To withstand abrasion and desiccation due to tough non-living surface layer composed of protein keratin wrapped in plasma membrane
As the keratinising stratified squamous epithelium making up the epidermis layer of the skin matures, what happens to the individual cells?
Their nucleus is eventually lost
How many layers of the epidermal layer of the skin can be identified easily?
What are the four layers of the epidermal layer of the skin that can be identified easily. Start listing from the top.
1. Stratum corneum
2. Stratum granulosum
3. Stratum spinosum
4. Stratum basale
What is the cell layer in the epidermal layer of the skin which is hardly seen in microscopy except possibly in the tissue from the soles of feet?
What is the stratum corneum?
The outermost layer of the skin consisting of keratinised cells
What is the stratum lucidum?
The stratum lucidum (Latin for "clear layer") is a thin, clear layer of dead skin cells in the epidermis named for its translucent appearance under a microscope. It is readily visible by light microscopy only in areas of thick skin, which are found on the palms of the hands and the soles of the feet.
What is the stratum granulosum?
The stratum granulosum (or granular layer) is a thin layer of cells in the epidermis. Keratinocytes migrating from the underlying stratum spinosum become known as granular cells in this layer.
What is the stratum spinosum?
The stratum spinosum (or spinous layer/prickle cell layer) is a layer of the epidermis found between the stratum granulosum and stratum basale.
What is the stratum basale layer in the epidermal layer of the skin?
The stratum basale (basal layer, sometimes referred to as stratum germinativum) is the deepest layer of the five epidermis layers, which is the outer covering of skin in mammals.
Describe what the stratum corneum layer would look like under a microscope
15-20 layers of flattened non-nucleated keratin material
Describe what the stratum granulosum layer would look like under a microscope
Coarse basophilic keratohyaline granules
Describe what the stratum spinosum would look like under a microscope
Large pale nuclei, prominent nucleoli. Intercellular bridges or tonofilaments seen
What type of division occurs in the stratum basale that results in regeneration and how often does the human epidermis renew?
Mitotic division leads to regeneration and human epidermis renews every 15-30 days