Integumentary system Flashcards
Name the 3 layers of the skin
epidermis, dermis and hypodermis
Explain the role of the epidermis
It is a stratified epithelium that contains keratinocytes which produce keratin fibres, they are tied together by desmosomes which create a long sheet that provides the epidermis with strength. The epidermis also acts as a physical barrier preventing entry of pathogens (primary defense)
The epidermis contains: keratinocytes, Merkel cells, melanocytes and dendritic cells
What is a desmosome
They are cell junctions which fuse cells together in tissues exposed to mechanical forces
Function of melanocytes
Are specialised cells involved in the production of melanin, (skin pigmentation) it acts as a sunscreen for keratinocytes and protects us from UV rays
Function of merkel cells
These cells are associated with nerve endings as they are involved in touch, texture and light response
Function of dendritic cells
These are antigen presenting cells (APC), they digest pathogens, rips them apart. They are a primary defense and activate the immune system, found deep within the skin
Name the layers of the epidermis from top to bottom
Stratum corneum
Stratum granulosum
Stratum spinosum
Stratum basale
Function of the basal membrane in the epidermis
It pushes the older dead cells to the top to be sloughed
Function of the stratum spinosum
They produce keratin from keratinocytes found in this layer, they also contain Langerhans cells which engulf and digest bacteria
Function of stratum granulosum
Consists of 4-6 layers of cells, they start to spread/flatten out, keratin is accumulated. Acute lamellae help keratin become waterproof
Function of stratum corneum
Consists of 20-30 layers of cells, thickest layer, these cells are programmed to die, as they become keratinised. This causes them to become very resistant to chemicals, water and mechanical pressures. Forms a solid physiological and biological barrier
Define & explain the process of sloughing
Sloughing is the shedding of cells, a normal part of the skin cycle, 50000 skin cells are lost per minute
This is a protective feature as we lose bacteria, flora from the skins surface. This is how the body physically cleans itself
occurs every 21-45 days
Describe the structure of the dermis layer
It contains: BV’s, elastic fibres, collagen, nerve endings, sweat glands and hair follicles
Has a papillary layer which provides a large SA of diffusion of nutrients, enhances the sense of touch
the reticular layer of the dermis provides elasticity and flexibility to the dermis (elastic & collagen fibres)
What are the main functions of the skin?
-primary defense
-physical barrier for bacteria, chemicals, water and mechanical pressures
-thermoregulation
-prevents UV damage
-secretion of sebum to waterproof skin
Purpose of sweating
Sweating allows the body to cool itself, to lower body temp, hair erector muscles relax and so hair lies flat. sweat is secreted from eccrine gland, water in the sweat then evaporates off skin surface, providing a cooling effect. Sweat also produces antibodies on skins surface in attempt to control microbiome