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What is the integumentary system?
your body’s outer layer designed to protect you
How much of an adult’s body mass is dedicated to the integumentary system?
16%
What are the two major components to the integumentary system?
dermis and epidermis
What is the “3rd” component?
hypodermis
What types of cells are in the epidermis?
keratinocytes and melanocytes
What do keratinocytes do?
produce keratin and repair skin
What do melanocytes do?
provide melanin and protection from UV radiation
How thick is the epidermis?
very thin, like a plastic bag
What is the difference between thick and thin skin?
thick skin contains stratum lucidum, thin skin does not
Where can you find thin skin?
almost everywhere on the body
Where can you find thick skin?
palms of your hands and soles of your feet
What are the five layers of skin (top to bottom)?
stratum corneum
stratum lucidum
stratum granulosum
stratum spinosum
stratum basale
What does the stratum corneum do?
prevents unwanted materials from entering, and excessive loss of water from exiting the body
What does the stratum lucidum do?
extra layer of protection, and prevents friction between corneum and granulosum
What does stratum granulosum do?
makes lots of keratin and kills cells, which creates densely packed protection
What does stratum spinosum do?
still alive, reacts to invaders
What does stratum basale do?
locks in epidermal ridges and dermal papillae to create a strong connection
Which layer is present in thick and thin skin, but is thicker in thick skin?
stratum corneum
Which layer is only present in thick skin?
stratum lucidum
What are skin pigments?
chemicals that are designed to absorb or reflect different wavelengths of light
What are the main skin pigments?
melanin and carotene
What is melanin’s purpose?
protects the body from UV radiation
How does melanin help block UV radiation?
it reduces the penetration of UV through the epidermis
How does melanin get its chemicals into cells?
melanocytes produce it, then send it into melanosomes and send it to epidermal cells
Why is UV radiation good?
helps create cholecalciferol (vitamin d3)
Why is UV radiation bad?
can cause cancer
What is the dermis?
the layer of skin between the epidermis and hypodermis
What are the defined layers?
papillary layer and reticular layer
What does the papillary layer do?
supplies nutrients to select layers of the epidermis and regulates temperature
What does the reticular layer do?
strengthens the skin, providing structure and elasticity
What is the reticular layer made of?
collagen and elastic fibers
Why are collagen and elastic fibers important?
they give the dermis strength and flexibility
How does water affect the dermis?
the turgor of the dermis allows it to resist stretching
What is turgor?
the ability to retain water
What is a stretch mark?
when collagen fibers are damaged
What are cleavage lines?
a map of the skin’s fibers
Why do surgeons care about cleavage lines?
if you cut along a cleavage line, it will leave minimal scarring, and if you cut across cleavage lines, it will damage fibers and scar a lot
What is a bruise?
when damage to the dermis ruptures the blood vessels in it
What structures exist in the papillary layer?
blood vessels, lymph, and sensory neurons
What are accessory structures?
tissues located in the dermis and epidermis that are not considered skin
What types of accessory structures are there?
hair, nails, and glands
What is hair?
an accessory structure that projects from the dermis to the outer environment
Where is hair located?
everywhere, except palms, bottom and sides of feet, lips, and parts of genitals
What are the three purposes of hair?
insulate the skin
protect the skin from damage
sense changes to the skin from the environment
What is a hair follicle?
the point where hair originates, surrounded by connective tissue (root hair plexus) and smooth muscle (arrector pili)
What is the hair root?
the part below the surface that anchors the hair into the skin
What is the hair shaft?
the part above the surface that is exposed to the environment
What is vellus hair?
hairs that are located all over the body and are less thick and lightly colored
What is terminal hair?
heavy and darkly pigmented hair
What are nails?
platelike, keratinous, translucent structures that consist of highly specialized epithelial cells
How do nails help us?
protect the exposed dorsal surfaces of fingers and toes, and provide protection when gripping an object by providing a backing so the cells don’t distort
What is the nail body?
the visible portion of the nail that covers part of your finger
What is the nail bed?
the part of your finger covered by the nail body
What is the nail hyponychium?
provides a seal to protect the nail body, located at the far distal edge of the nail
What is the nail root?
an epidermal fold where the nail grows from
What is the cuticle?
a section of nail root that comes over the exposed surface of the nail
How do nails tell us about our health?
yellow nails can be a sign of various disorders, so can pitted nails (low iron) or clubbed nails (low oxygen levels)
What are the two types of glands?
sebaceous and sweat glands
What do sebaceous glands do?
discharge an oily secretion
What do sweat glands do?
release a watery liquid
What is sebum?
the lipids produced by sebaceous glands (made of cholesterols, triglycerides, proteins, and electrolytes)
What are the two types of sebaceous glands?
sebaceous glands (associated with a hair follicle) and sebaceous follicles (not associated with a hair follicle)
What are the two types of sweat glands?
apocrine (secrete products onto hair follicles and where there is skin to skin contact) and merocrine (secrete products onto skin)
Where are apocrine sweat glands located?
arm pits, nipples, genitals (produce a sticky, oily secretion and become active at puberty)
Where are merocrine sweat glands located?
everywhere (watery sweat meant to cool you down)
What is the hypodermis/ subcutaneous layer
lowest layer, important in stabilizing skin
What tissues make up the hypodermis?
adipose and areolar tissue
Is there blood flow to the hypodermis?
yes, a lot of it
What happens if the blood flow in the hypodermis is constricted?
people will turn white and can faint
What is baby fat?
excess adipose tissue designed to prevent heat loss and protect vital organs as children
What do males and females have in common when it comes to adipose tissue
both will have more on the abdomen and butt
How do males and females differ when it comes to adipose tissue?
men generally have more on the neck, arms and lower back and women have more on the hips, breasts, and thighs
What is a hypodermic needle?
a delivery system designed to administer medicine to the hypodermis
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