anatomy 1 exam 3

the integument of an organism refers to its

outer layer of tissue

the integument is the

skin

the integumentary system includes the

tissue of the skin and the organs embedded in it

some examples of what is embedded in the integumentary system

blood vessels, nerves, glands and appendages like hair and nails

the integumentary system performs the following life functions

1. maintaining boundaries

2. responsivness

3. homeostasis

4. metabolism

5. excretion

the skin is a protective barrier between the body and the outside environment

maintaining boundaries

the skin has a variety of receptors for the senses of touch, pain, temp, and more

responsiveness

the skin is involved in the homeostasis of body temp called thermoregulation

homeostasis

the skin is important in storing and metabolizing energy, nutrients, and vitamins

metabolism

the skin removes waste in products in sweat and skin oil

excretion

outer layer of skin

epidermis

outer layer consists primarily of

stratified squamous epithelial tissue

middle layer of skin

dermis

middle layer of skin consists of

2 layers of fibrous connective tissue

inner layer of skin

hypodermis

the inner layer of skin consists of

adipose tissue

epidermis has 2 major functional regions

1. keratinized layers

2. regenerative layers

20-30 layers of dead squamous epithelial cells filled with the protein keratin

keratinized layers

layers of living cells that grow and develop new cells to replace those lost from the keratinized layer

regenerative layers

dermis has 2 major regions

1. papillary layer

2. reticular layer

thin “wavy” layer immediately underneath the epithelium made of areolar CT

(has equal collagen and elastin)

papillary layer

thick lower layer immediately underneath the papillary layer made of dense irregular CT (bundles of collagen has the strength to resist physical forces in multiple directions)

reticular layer

made of adipose tissue, highly vascular, connects the skin to bones and to the muscles

hypodermis

all the vessels that bring blood to the dermis and epidermis come from the

hypodermis

intradermal injections are done at

a low angle to keep the injected material stuck in the dermis (slow absorption)

subcutaneous injections are done at

a 45º angle to place injected material near the blood vessels of the hypodermis (fast absorption)

intramuscular injections are done at

90º angle to place injected into muscle tissue (fastest absorption)

keratinocytes make up the

vast majority of the cells of the skin

keratinocytes name come from the fact that during their development they become

completely filled with keratin proteins

keratinocytes are made in the

bottom-most parts of the regenerative layers

the keratinocytes migrate upward over about

30-40 days as they develop into keratinized cells

epidermal stem cells (ESCs) are responsible for

producing the cells that develop into keratinocytes

ESCs are located in the

bottom-most layers of the regenerative layers

ESCs are closest to the blood vessels found in the

dermis

the location of ESCs are important for providing

the nutrients necessary for powering mitosis

melanocytes are named because they produce

packets of the molecule melanin

like ESCs the melanocytes are found only in the

bottom-most layers of the regenerative layers

melanocytes constantly produce and secrete

small packets of melanin called melanosomes

melanosomes are absorbed by

developing keratinocytes

highly sensitive receptors for touch

tactile cells

each tactile cell is attached to a

nerve from the dermis

tactile cells are found in large numbers around

hair follicles and in touch-sensitive areas of the skin

ex. palms, fingertips, and lips

dendritic cells are not truly “skin cells, they are

cells of the immune system

dendritic cells identify

micro-organisms and other non-human materials

dendritic cells identifying micro-organisms and other non-human materials allows them to

activate the immune system to fight off infections

immune cells like dendritic cells are not unique and are found near

every epithelial layer that faces the environment

the skin boundary is one of the body’s most important

protective barriers

skin resists the entry of

micro-organisms and toxic chemicals into the body

skin resists the

loss of water to the outside of the body

skin protects sensitive tissues underneath the skin from

physical damage

skin protects body tissues from

exposure to UV radiation from the sun

dozens of layers of epithelial cells form a

physical protective boundary

normal physical wear and tear of the skin slowy

removes the keratinized layers of the epidermis

regenerative layers constantly grow new keratinized cells to

replace those that are lost

the function of regenerative layers helps to prevent/resist damage to living tissues underneath by having those

damaged be absorbed by dead, replaceable cells

the cells of the epithelium are sealed together using

cell junctions

cell junctions are built using proteins that are

cell adhesion molecules

spaces between the junctions are so small that only

water and other very small molecules can move between the cells

cell junctions connect epithelial cells in a giant

network that has enhanced physical strength and resits physical damage

the cells of the keratinized layer are filled with

keratin proteins

extremely strong, fibrous protein

keratin

cells in the keratinized layer will produce keratin protein until

their cytoplasm becomes completely filled with bundles of keratin fibers

bundles of keratin make the keratinoctye that are

water-resistant and extremely durable against physical forces

keratinocytes in the top-most regenerative layers make

lamellar granules

lamellar granules are filled with a wide variety of

lipid-based hydrophobic molecules

the lipid-based hydrophobic molecules are secreted into

the space between keratinocytes

the chemistry of the the secretions into the space between keratinocytes create 2 important conditions in the skin:

1. together with the cell junctions they form a water-resistant epidermal water barrier

2. the acidic pH (around 5) of these molecules gives the keratinized layer an anti-microbial barrier called the acid mantle

connective tissues of the dermis enhance

the strength of the skin

the reticular layer of the dermis contains

dense irregular CT

dense irregular CT has

large bundles of collagen arranged randomly in the ECM

this dense arrangement of collagen in dense irregular CT gives the skin the strength to

stand up to physical forces from any direction

the ability to stand up to physical forces from any direction makes the physical barrier of the skin

resistant to damage and breakage

epidermal cells are filled with packets of

melanin

melanin does not form a physical boundary, it instead forms a

photoprotective boundary

sun exposure causes exposure to UV radiation that can

damage the DNA of cells

if UV radiation damage is repeated over a long period of time, the accumulated DNA damage can lead to

cell death or development of cancer

melanin pigments can safely absorb

UV radiation

key job for any healthcare-related profession is maintaining the

skin integrity of pt/clients

the maintenance of the complete and intact physical structure and a healthy chemical environment for the skin

skin integrity

skin integrity allows pts/clients to constantly maintain a

healthy boundary between their body and the environment

because there are a large number of ways that the skin forms a boundary, there are a large number of ways that

skin integrity can be comprised

5 ways skin integrity can be compromised

1. wounds

2. prolonged pressure or friction

3. excessive dampness

4. excessive dryness

5. burns

complete break of the skin’s boundaries in that location

wound

while the wound heals the break, we must use wound care methods to

temporarily close the break and promote natural healing

prolonged exposure to physical forces can wear away the

skins physical protective barrier over time

bony structures that are in close contact with the skin

pressure points

the spot where the skin tissue wears away is called a

pressure ulcer or bedsore

prolonged exposure to water causes the skin to soften and swell which

reduces its physical strength and increases risk of pressure ulcers

excessive dampness also alters the chemical environment of the skin by

removing skin oils and stripping molecules out by diffusion

the removing of skin oils and stripping molecules out by diffusion increases the risk of

infection

excessively dry skin will

crack or break open the skin’s physical barrier

excessively dry skin can be caused by

prolonged exposure to dry air or loss of skin oils

skin oil loss can be caused by

harsh detergents/cleaners, excessive washing, certain medications, certain skin disorders

burns will

break the physical barrier of the skin in the same way as wounds

burns increase the risk of

infection

severe burns can cause

dehydration due to the loss of water-resistant skin layers and low body temp (hypothermia) due to the loss of insulating fat of hypodermis

skin is home for the 3 main types of body sense receptors

touch, pressure, and vibration

thermoreceptors sense

temperature

nociceptors sense

pain

the sensitivity of the skin to the three senses is determined by the

density of skin receptors in each region