Skin Flashcards
What is the largest organ in the body?
Skin
Skin comprises about 16% of the body’s weight and has a surface area of approximately 1.8 m².
What is the thickness of the skin on the palms of hands and soles of feet?
0.8-1.4 mm thick
The skin on eyelids is much thinner at about 0.05 mm.
Name the three main layers of the skin.
- Epidermis
- Dermis
- Hypodermis
What type of cells predominantly make up the epidermis?
Keratinocytes
The epidermis is a stratified squamous epithelial layer.
What is the primary function of the dermis?
Supportive connective tissue matrix
It is made up of fibroblasts and immune cells.
What is the hypodermis primarily composed of?
Adipose tissue
It provides insulation and energy reserves.
What are rete ridges?
Structures that increase surface area between the epidermis and dermis
They help prevent blister formation.
How does skin adapt to frequent abrasion?
By producing more skin
This adaptation involves the development of more robust epidermal layers.
What is the role of melanocytes in the skin?
Synthesize melanin
Melanin absorbs UV radiation and protects against DNA damage.
What is the primary function of Langerhans’ cells?
Act as antigen-presenting cells
They help in the immune response by processing microbial antigens.
What are the two layers of the dermis?
- Superficial papillary layer
- Underlying reticular layer
What is the function of fibroblasts in the dermis?
Produce collagen and elastin
They provide tensile strength and flexibility to the skin.
What is the composition of sweat?
- Mainly water
- Minerals
- Urea
- Lactate
- Fatty acids
What type of sweat glands are most numerous on the palms and soles?
Eccrine sweat glands
They are under thermal control for thermoregulation.
What distinguishes apocrine sweat glands from eccrine glands?
Apocrine glands are primarily located in specific areas like the armpits and are associated with hair follicles.
What happens to the basal layer cells after a cut?
They produce more skin, which can lead to scar formation
Darker skin types may produce keloid scars.
What is keratinocyte maturation important for?
- Normal epidermal turnover
- Wound healing
- Prevention of skin cancer
What is the role of the cornified layer of the skin?
Forms a protective surface
It consists of terminally differentiated cells that are flattened.
How does skin maintain homeostasis regarding temperature?
Vessels dilate and sweat is produced
This helps cool the body when overheated.
What is the significance of the granular layer in the epidermis?
Contains keratohyalin granules and lipid-filled lamellar granules
These contribute to waterproofing the skin.
What are the two types of hair?
- Vellus hairs
- Terminal hairs
What is the primary function of nails?
Protect fingers with densely packed keratin
Nails are composed of a dense plate of cells.
What is the mechanism of sensation in the skin?
Nerves in the epidermis and dermis provide perception
Includes Merkel cells and various corpuscles for touch and pressure.
Fill in the blank: The epidermis is made up of _______.
[keratinocytes, melanocytes, Merkel cells]
True or False: The dermis varies in thickness, being thinnest on the eyelids.
True
What are the primary functions of skin?
- Acts as a barrier
- Prevents water absorption
- Prevents injury
- Mechanism of sensation
- Thermoregulation
What is the role of sebaceous glands?
Produce oily sebum
Sebum protects hair and skin from dehydration.
