Integumentary System

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)?

1. stratum corneum

2. stratum lucidum

3. stratum granulosum

4. stratum spinosum

5. 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?

1. insulate the skin

2. protect the skin from damage

3. 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