TEAS Integumentary

What are the functions of skin?

Homeostasis, temperature regulation, fluid balance, barrier against pathogens, vitamin D synthesis, sensory function

What are the three main layers of skin from outermost to innermost?

Epidermis, dermis, hypodermis

Does the epidermis have blood vessels?

No — only the dermis contains blood vessels

What is the hypodermis made of?

Primarily adipose tissue — provides insulation — connects skin to underlying bone and muscle

What is the order of epidermal layers from outermost to innermost?

Stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale — mnemonic: Come Let's Get Some Beer

What is the stratum corneum?

Outermost layer — dead cornified cells that constantly slough off

What is the stratum lucidum?

Found only in thick skin — palms and soles of feet

What is the stratum granulosum?

Keratinocytes flatten and accumulate granules — forms a waterproof layer

What is the stratum spinosum?

Contains Langerhans cells that act like macrophages — consuming worn cells and bacteria

What is the stratum basale?

Deepest epidermal layer — single layer undergoing constant mitosis — contains melanocytes and Merkel cells

What do melanocytes do?

Produce melanin — provides skin color and UV radiation protection — located in stratum basale

What are Langerhans cells?

Immune cells in stratum spinosum that consume worn out cells and bacteria

What are keratinocytes?

Main cells of the epidermis — produce keratin — migrate upward from stratum basale

What do fibroblasts do?

Produce collagen and elastin in the dermis

What does collagen do in the dermis?

Provides structural support

What does elastin do in the dermis?

Provides elasticity — allows skin to return to shape after stretching

What do sebaceous glands produce?

Oil (sebum) — waterproofs and lubricates skin and hair

What is the most common skin cancer?

Basal cell carcinoma — from stratum basale cells

What is the most aggressive skin cancer?

Melanoma — from melanocytes

What causes squamous cell carcinoma?

UV radiation — arises from squamous cells in the outer epidermis

What are the four degrees of burns?

First: epidermis only — Second: epidermis and upper dermis — Third: full epidermis and dermis — Fourth: down to muscle and bone

Why do third and fourth degree burns hurt less?

Nerve damage from deep tissue destruction reduces pain sensation