Structure of the skin - The Epidermis Flashcards
The Integument as an organ is also known as :
Skin
The Integumentary system includes :
Skin and skin derivatives(Hair, Nails, Sweat glands)
The integumentary system is the ________ system in the body.
largest
The integument is made up of two parts:
Cutaneous membrane and Accessory structures
Cutaneous membrane consists of :
Epidermis and Dermis
Epidermis
Superficial epithelium
Dermis
Underlying cutaneous tissue with blood supply
Accessory structures consists of :
Hair, Nails, Exocrine glands
Functions of integumentary system (PASSIFS)
Protection Absorption Secretion Sensation Ion Transport Fluid Filtration Slippery Surface
Functions of the integument as protection
- Acts as first line of defense against bacteria and viruses.
- Protects underlying structures from UV radiation and Dehydration
Function of the integument as secretion
Small amounts of waste products are lost through perspiration.
Function of the integument as sensation
Sensory receptors detect temperature, pressure, pain and itch.
Body temperature regulation if it is too hot
- Dermal blood vessels dilate.
- Vessels carry more blood to surface so heat can escape.
Body temperature regulation if it is too cold
- Dermal blood vessels constrict.
- Prevents heat from escaping.
3 structural layers of the skin
Epidermis
Dermis
Hypodermis
Describe epidermis
It is a stratified squamous epithelium.
Most abundant cells in epidermis
Keratinocytes
Number of layers of thin skin
4 layers of keratinocytes
Number of layers of thick skin
5 layers of keratinocytes
Thick skin are found in :
the sole of the feet and the palm of the hand.
The five strata of keratinocytes in thick skin
Stratum Basale Stratum Spinosum Stratum Granulosum Stratum Lucidum Stratum Corneum
The four strata of keratinocytes in thin skin
Stratum Basale
Stratum Spinosum
Stratum Granulosum
Stratum Corneum
Stratum basale is attached to ________ by _______.
basement membrane; hemidesmosomes
Stratum basale forms
epidermal ridges
Stratum basale contains
dermal papillae
Cells found in stratum basale
Keratinocytes
Melanocytes
Merkel cells
Stratum spinosum is a spiny layer produced by _______ of _______.
division; stratum basale
In stratum spinosum, ________ shrink until ________ stick out(spiny).
cells; cytoskeleton
Cells found in stratum spinosum
langerhans cells
Stratum granulosum is a _______ layer and is the layer where _______ stop _______.
grainy; cells; dividing
The layer that starts producing keratin
Stratum granulosum
Keratin
A tough, fibrous protein which makes up hair and nails.
The layer that covers stratum granulosum
Stratum lucidum
Stratum lucidum is a ______ layer found only in _____ skin.
clear; thick
Stratum corneum is the _____ layer which is the exposed ______ of the ______ .
horn; surface; skin
Layers of keratinized cells in the stratum corneum
15 to 30 layers
The stratum corneum is _______ resistant.
water
The stratum corneum is shedded every _________.
2 weeks
Layer of the epidermis where mitosis takes place
Stratum germinativum/basale
The innermost layer of the epidermis
Stratum basale
Process of mitosis in stratum basale
New cells are continually being produced, pushing the older cells toward the skin surface.
The cells of stratum basale produces
Keratin
Location of Merkel cells in the epidermis layer
Stratum germinativum
Merkel cells are responsible for
the sense of the touch
The anti-microbial peptides that living keratinocytes sysnthesize are called
Defensins
When are defensins produced?
They are produced following any injury to the skin, as part of the process of inflammation.
Function of Defensins
Defensins will rupture the cell membranes of pathogens such as bacteria that may enter the body by way of breaks in the skin.
What vitamin does the living portion of the epidermis produces?
Vitamin D
Importance of Vitamin D
It is important for absorption of Calcium & Phosphorus.
Outermost epidermal layer
Stratum corneum
Stratum corneum consists of
Dead cells that have only keratin
Which protein in the skin is relatively waterproof?
Keratin
________ prevents the entry of water in the stratum corneum.
Keratin
Which epidermal layer acts as barrier to pathogens and chemicals
Stratum corneum
Which substance inhibit the growth of microorganisms in skin
Sebum
Which cells are able to phagocytize foreign material, such as bacteria that enter the body through breaks in the skin?
Langerhans cells
Melanocytes produces another protein called
Melanin
Which two parts of the eye obtain their color from melanin?
Iris, and Interior Choroid layer of the eyeball.
Dark hair contains
True melanin
Blond and red hair result from types of melanin that contain
Sulfur and Iron
When does hair goes gray?
When melanocytes age and lose the enzyme necessary to produce melanin.
Genetic condition resulting in a total lack of melanin
Albinism
Type of tissue in the dermis
Irregular fibrous connective tissue.
What happens to our elastic fibers when we get increasingly old?
The elastic fibers degrades causing the skin to lose its elasticity.
The uneven junction of the dermis with the epidermis is called
Papillary layer.
Capillaries are only found in the
Dermis
Hair follicles are made up of
Epidermal tissue
Functions of human hairs
- Eyelashes and eyebrows help to keep dust and perspiration out of the eyes.
- Hairs inside the nostrils help to keep dust/pollens out of the nasal cavities.
- Hair of the scalp does provide insulation from cold for the head.
