What is the epidermis made out of and where is it thickest?
Stratified squamous keratinizing epithelial tissue and thickest on psalms and soles
The protein keratin is produced and surface cells are dead
What are squamous epithelial tissue?
- Made of many layers of flat cells
- Mitosis takes place in the lower layers to replace the skin that has worn out at the top layer
What happens in the stratum germinativum?
- Lowest layer
- Mitosis takes place here, pushes older cells toward the skin surface
What are Merkel cells?
They are receptors for the sense of touch
Why are the cells at the top dead?
Because they have moved to far from the the capillaries and have no nutrients
How is vitamin D produced?
- It is produced by living keratocytes who produce a cholesterol
- that with exposure to UV light turns to vitamin D
What do you call the outer most layer?
What makes the skin water proof?
The presence of keratin as it prevents the entry of water
What is a first degree burn?
- A burn where only the superficial skin is burnt
- Appears red due to vasodilation in the damaged area
What is a second degree burn?
What are Langerhans cells?
They are dendritic cells
Where are melanocytes found
in the lower epidermis?
What is the function of melanocytes?
Produce a protein, pigment called melanin on exposure to UV light
The function of dendritic cells?
They are antigen-presenting cells, they present it to the surface of t-cells
- Phagocytize foreign material
- and stimulate an immune
- response by lymphocytes
What is the dermis made up of?
An irregular type of connective tissue
Strength and elasticity are characteristics
What do the call the junction between the dermis and epidermis?
- the papillary layer
- Capillaries are abundant here to nourish not only the
dermis but also the stratum germinativum.
Name all the layers of the integumentary system
Stratum corneum, lucidum, granulosum, spinosum, basale
What is the appearance and function of the stratum spinosum
Appears to be covered in thorn like spikes, providing the skin with strength and flexibility
What is the appearance and function of the stratum granulosum?
- Site of keratin formation
- has keratinocytes
- keratohyalin gives it it's granular appearance
Where is the stratum lucidium found?
- In the soles, palms and fingertips.
- Made up of dead keratinocytes
What provides water repellent action?
the Lamellar granules, they are continuously shed and replaced
What do langehanns cells do?
- Regulate immune reactions in the skin
- Ingest antigens and present them to the cells of the immune system
What is the dermis tissue composed of?
Connective tissue, blood vessels, nerves, glands and hair follicles
What are the cells in the epidermis?
- Merkel cells
- Langerhans cells
What do the elastic fibres in the dermis help with?
strength and elasticity
What is the subcutaneous tissue made up of?
an insulating layer of fat and blood vessels
What is the function of the subcutaneous tissue?
Maintain body temperature and offers protection to all the organs
What are the sweat glands used for?
What is the function of hair?
Protection, thermoregulation and sensing light touch
What is hair composed of?
elongated dead keratinized cells that are bound by extracellular proteins
Where is hair not found?
Found everywhere on human body except palms, soles, lips, nipples, parts of external genitalia, and distal segments of fingers and toes
What is the hair shaft?
the superficial portion that extends out the skin
What is the hair root?
the portion that penetrates the dermis