How much area does the skin cover?
about 2 square meters (22 square feet)
How much does the skin weigh?
4.5-5 kg (10-11 lb)
What are the 2 layers of skin?
Epidermis and Dermis
What is the epidermis derived from?
the embryonic ectoderm
What is the dermis derived from?
the embryonic mesoderm
What layer is found beneath the dermis?
hypodermis (the subcutaneous tissue)
What is the function of the hypodermis?
it anchors the skin loosely to the underlying tissues (muscle)
What does the skin do when its hot?
Receptors in the skin send signals to the hypothalamus which will trigger the skin to release water and sodium which will cool the skin via convection
What does the skin do when its cold?
Blood vessels constrict to prevent heat loss, there is involuntary muscle contraction (shivering), and the subcutaneous fat preserves heat
What is a dermal papilla?
a cone shaped protrusion at the base of the follicle which feeds blood and therefore nutrients to the hair bulb
What is a sebaceous (oil) gland?
a gland that lubricates and keeps the hair healthy and shiny
What is an arrector pili?
a tiny muscle anchored to the follicle that contracts and make the hair stand up straight
What 2 types of stimuli do arrector pili respond to?
scary and cold stimuli
What type fiber types are found in the dermis?
collagen and elastin
What is the function of the dermis?
It provides skin tone and accounts for the strength and toughness of the skin
What structures are found in the dermis?
Afferent nerve endings
What is the hypodermis composed of?
mainly adipose tissue plus some areolar tissue
What are the 3 types of burns from least sever to most?
1) 1st degree (superficial)
2) 2nd degree (partial thickness)
3) 3rd degree (full thickness)
What layers of the skin are damaged in a 1st degree burn?
just the epidermis (sunburn)
What layers of the skin are damaged in a 2nd degree burn?
the epidermis and into the superficial part of the dermis
What is characteristic of a 2nd degree burn?
What layers of the skin are damaged in a 3rd degree burn?
The entire epidermis and dermis are destroyed, and part of the hypodermis is damaged
What is characteristic of a 3rd degree burn?
loss of bloodplasma by exudation and often times blackened skin
What is required in order for a 3rd degree burn to heal?
a skin autograph
What is cyanosis?
It is a blue discoloration of the skin caused by an excess of deoxygenated hemoglobin in the blood or a structural defect in the hemoglobin molecule
If a person suffers a burn on the forearm that destroys the epidermis and a portion of the dermis would you expect to find hair growing in the area of the injury after it heals?
Yes, because it does not damage the subcutaneous layer where the hair receives it’s blood supply and nutrients