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For more information, please see full course syllabus of Anatomy & Physiology
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Lecture Comments (17)

2 answers

Last reply by: Berry Adams
Mon Nov 28, 2016 9:48 AM

Post by Berry Adams on October 22, 2016

How does the structures of the epidermis allow it to provide immediate and indirect protection to underlying tissues?

2 answers

Last reply by: Berry Adams
Sat Oct 22, 2016 3:04 PM

Post by Berry Adams on October 22, 2016

What would be the consequences if a person's skin glands stopps functioning?

1 answer

Last reply by: Bryan Cardella
Mon Jan 5, 2015 10:39 AM

Post by Javier Lopez on January 4, 2015

Melanin is the product of melanocytes. This protects the organism especially from UV Rays as well from other situations,such as an irritation. So then What race was first?
¨African¨- have a high production of Melanin(maybe because of the UV Rays that affected DNA)
¨Albino¨-Have in active melanocytes (unnecessary function because of style of life or change in environment)

2 answers

Last reply by: ye Chaoran
Sun May 14, 2017 7:08 AM

Post by Emma Brun on December 11, 2014

Why doesn't my scalp bleed if i pull a hair out (considering there are capillaries at the roots of the hair)?  

1 answer

Last reply by: Bryan Cardella
Tue Jul 1, 2014 6:04 PM

Post by David Gonzalez on June 30, 2014

Were scabs something created specifically by the body to help protect a cut from further infection? Or did they just occur on their own and ended up being really beneficial?

1 answer

Last reply by: Bryan Cardella
Fri Apr 4, 2014 1:56 PM

Post by Kayla Steiner on April 3, 2014

Why is it that some people can grow their hair to their belly button, when others can only grow it to their shoulders?

1 answer

Last reply by: Bryan Cardella
Tue Feb 4, 2014 10:17 AM

Post by Okwudili Ezeh on February 3, 2014

can i get the transcripts of the A&P lectures.

Related Articles:

Integumentary System (Skin)

  • The functions of skin include protection, absorption, secretion, heat regulation, and aesthetics
  • Major layers of skin include the epidermis, dermis, and subcutaneous layer (hypodermis)
  • The epidermis (most superficial layers) contains keratin-producing cells and melanin-producing cells, separated from the dermis by the stratum basale
  • The dermis (middle layers of skin) has blood flow, hair (follicles/shafts), glands (sebaceous, eccrine, apocrine), arrector pili muscles, nails, and nerve endings
  • The subcutaneous layer (deepest part) contains fat storage and arteries and veins that supply blood flow to the layers superficial to it
  • Cuts are healed through a 4-step process (inflammation, migration, proliferation, and maturation)
  • Burns are caused by heat, chemicals, electricity, or friction and they can be as minor as 1st degree, or 2nd, 3rd, or 4th degree at the worst
  • The Rule of Nines helps emergency medical personnel communicate quickly about how extensive burns are to a person’s body
  • Skin conditions/disorders include scars, moles, freckles, melanomas and carcinomas
  • Did you know…
    • Q: My friend sweats a lot more than the average person…and in the oddest places too. She sweats from her lower legs even when her body heat is not that extreme. Is there a way to correct this or a surgery that will turn off these glands?
    • A: Yes, laser surgery can actually disable sweat glands. These would be done sparingly because turning off too many sweat glands would cause massive overheating in the body. In places like the lower legs where the average person does not sweat that much (compared to the forehead, armpits, or upper back) sweat glands could be disabled to make a person feel more comfortable and less self-conscious about profuse sweating.

Integumentary System (Skin)

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • Functions of the Skin 0:07
    • Protection
    • Absorption
    • Secretion
    • Heat Regulation
    • Aesthetics
  • Major Layers 3:50
    • Epidermis
    • Dermis
    • Subcutaneous Layer (Hypodermis)
  • The Epidermis 5:56
    • Most Superficial Layers of Skin
    • Epithelial
    • Cell Types
    • Cell Type: Melanocytes
    • Cell Type: Keratinocytes
    • Stratum Basale
    • Helps Form Finger Prints
  • Dermis 11:54
    • Middle Layers of the Skin
    • Blood Flow
    • Hair
    • Glands
    • Sebaceous Glands
    • Sweat Glands
    • Arrector Pili Muscles
    • Two Main Kinds of Hair: Vellus and Terminal
    • Nails
    • Cutaneous Receptors (Nerve Endings)
  • Subcutaneous Layer 25:00
    • Deepest Part of the Skin
    • Composed of Connective Tissue
    • Fat Storage
    • Blood Flow
  • Cuts and Healing 26:33
    • Step 1: Inflammation
    • Step 2: Migration
    • Step 3: Proliferation
    • Step 4: Maturation
  • Burns 32:44
    • 1st Degree
    • 2nd Degree
    • 3rd Degree
    • 4th Degree
    • Rule of Nines
  • Skin Conditions and Disorders 40:02
    • Scars
    • Moles
    • Freckles/ Birthmarks
    • Melanoma/ Carcinoma
    • Acne
    • Warts
    • Wrinkles
    • Psoriasis
    • Eczema/ Rosacea
    • Vitiligo

Transcription: Integumentary System (Skin)

Hi and welcome back to

This is the lesson on the integumentary system also known as the skin.0002

When we look at the skin, it has several functions that keeps us alive and maintain homeostasis.0006

Protection is a major one that we think about the outside or superficial portion of our integumentary system are all epidermis stratified squamous epithelium.0013

If you watch lesson 2 on tissues.0024

It helps protect us, think about all the bacteria and viruses that will quickly get into our body if it was not for this outside protective layer.0027

It is one of the first line of defense in protecting our body from pathogens or foreign invaders.0037

Absorption, is not just absorption of sunscreen or nicotine.0042

One natural absorption that happens everyday is when you are outside and the sunlight is hitting you,0047

the UV of the sun is penetrating into the layers of your skin causing degeneration of vitamin D from that UV radiation.0055

You can absorb other things, there is slight absorption of water into the layers of your skin.0064

Your skin is not really water proof but it is water resistant.0069

The regulation is how much is absorbed and you can thank your skin for that.0074

Secretion a lot of products are secreted.0079

It is the opposite of absorption.0082

Secretion is not just sweat but it is a major one.0083

Sweat is mostly water but there are little particles in the water too.0087

Electrolytes are what you lose when you sweat a lot.0091

That is why people drink energy drinks full of electrolytes or eat bananas to replace the potassium that is lost.0095

Secretion is one way of getting the sweat out in terms of regulating body heat and releasing some waste products through sweat.0102

Speaking of body heat not just in terms of cooling the body down through sweating but the opposite it is preventing the body from getting too cold.0112

Every time you get goose bumps or goose pimples that is because the pores in your skin are stimulated to close and the hairs in those pores stands straight up.0123

Thanks to muscular action in your dermis.0131

You do not consciously control those muscular contractions but that is part of keeping heat in when you get those goose bumps.0134

Aesthetic means beauty and if you find someone attractive when you look at them, what your eyes is seeing is the light reflecting off their epidermis.0141

That is what we notice when we look at someone, that is the outer portion of the skin.0154

If you are attracted to them, thank their skin for their aesthetic quality.0159

This is a lovely diagram from Grey’s Anatomy, not like the TV show but it is a play on word that is why that TV show is called that.0165

The show on TV Grey’s Anatomy is named after a puny way from Gray which is a famous anatomical text book.0170

It is used a lot of medical schools because it has so many good diagrams and details in terms of labeling the body parts and describing their functions.0184

This is a classic look from the Gray’s Anatomy and you can tell that this particular font is common in Gray’s Anatomy and the style of drawing.0191

This drawing is to look at the different layers of skin.0201

Up here superficially we got the epidermis, here you see dermis, it is very thick layer of skin, and hypodermis or the deepest levels or the subcutaneous layer.0205

Here is a little bundle of fat associated with that.0223

Here is a great drawing of where the major layers of the skin are separated.0228

First we will talk about the epidermis.0238

You could see that the epidermis exist from the most superficial portions and the top layers stratum corneum and down to the end of this purple section.0242

Down here is the deepest part of the epidermis.0253

You could see how it is wavy this is the stratum basale which I will talk about in the future.0262

This is the basement membrane that anchors all the epidermal cells.0269

You have a few different cell types in there mostly epidermis is dead and the parts that are not are near the blood flow.0274

The blood flow comes up to the most superficial portions of the dermis.0284

Just deep to the dermis is a very thick layer exist here.0289

The actual border between the dermis and hypodermis or subcutaneous layer is not well defined.0297

The border between the epidermis and dermis is well defined by the stratum basale.0304

You could see that depending of what portion of the skin you are in the amount of yellow stuff in here is going to vary in terms of how deep or superficial it is.0309

The border between the dermis and hypodermis is not as well defined as the one on top.0318

In the dermis you got a lot going on, hair, sweat glands, blood flow, neurons, all kind of stuff that we will cover a little bit in the lesson.0323

Like I said the subcutaneous layer also known as hypodermis meaning under or below that is mostly fat bodies0334

and major blood vessels in terms of the veins and arteries that are feeding your skin to superficial portions of it with oxygen and nutrients.0345

Let us start with epidermis, the most superficial layer of skin.0356

It is not just one layer.0361

People tend to think that the epidermis is just one layer on the outside.0363

It tends to be 10-30 cells thick.0366

I wrote epithelial here because if you saw lesson 2 on the different types of tissues, epithelium lines the outside of organs0370

and the innermost cavities of the organs where you have space or passageways.0378

All of the epidermis is basically composed of stratified squamous epithelium those stacks of round, plate like cells from the bottom to the top.0383

Depending on where you are on the body it may be 10 cells, 30 cells, or more.0396

Let us take the eyelids, this is one of the thinnest part of your skin in your entire body.0400

You will imagine the amount of epidermal cells significantly less than the palm of your hands or the soles of your feet.0406

You can feel that the skin is thicker here and you develop that callous that is even greater thickening of the skin0414

in response to friction whether you are swimming or lifting something.0419

The extra friction that you experience on daily basis with your hand touching things and your feet walking0425

it is the reason why you will get extra epidermal development there.0430

The two main kinds of cells that you would see in the epidermis are the melanocytes and the keratoncytes.0435

Let us start with melanocytes.0445

Melanocytes tends to be scattered in the stratum deranitivum layer, the deepest part of the epidermis.0447

Let me draw what it looks like and I will explain what these little finger like projections are.0456

That is a melanocyte and underneath that you would see the basement membrane also known as the stratum basale0467

which is the well defined border between the epidermis and the dermis underneath it.0481

You tend to see melanocytes along the deepest parts of your epidermis.0485

The melanin that is produced is the pigment that ends up in your skin, hair, iris of the eyes that gives color.0494

The more melanin you produce that darker your skin is going to be.0501

You got production of melanin in the melanocytes, and cyte means cell.0506

Those melanin deposit ends up in these little cellular extensions of the melanocytes that go out more superficially.0516

They allow depositing of melanin in cells that are bit higher up in the epidermal layers.0526

The darker you skin is the more melanin your melanocytes are producing.0537

Even you are an albino, somebody who has no hair pigment you are still filled melanocytes0542

because it is natural to have this cell in the epidermis but their melanocytes are inactive.0550

They do not produce melanin that is why they have this pale look and they are more sensitive to UV radiation and getting skin cancer.0555

Melanin not only provides color to your skin but also protective in terms of shielding your skin cells from their DNA getting harmed by UV radiation.0563

Keratinocytes these produce keratin.0578

Keratin is a protein that is meant to be protective for you skin and helps your skin in terms of water resistance.0581

They are scattered through the epidermis.0592

The ones in the deeper parts are resulting from cell division from the mitosis.0596

As the keratinocytes are pushed up farther they get more dead because they are getting pushed away from the blood flow from all the capillaries of the dermis.0603

The way that the epidermis gets nutrients is through diffusion up into those layers of the epidermis but the farther away they are completely dead0614

and they are jam packed with keratin with this protein that is giving your skin protection and helping shield it from too much water getting in and out.0630

When I do this I am brushing off many cells and thankfully I am going to produce more skin cells to take the place of the ones that has been brushed off from the top portions.0639

The stratum basale is that layer here that separates the epidermis from the dermis.0654

From lesson 2 that is the base membrane of this epithelium.0664

One more thing the stratum basale helps form the finger prints.0669

Identical twins who have the same DNA from their parents do not have the same finger prints.0675

They will make different finger prints when you take them and the reason is as their skin is developing in the uterus0681

while they are in the womb the way that their early skin is affected by the moving in the amniotic fluid0685

and rubbing against the inside of the amniotic sac that they are in that manipulates how the stratum basale is formed in terms of the exact peaks.0694

That formation in the womb results in finger prints and that is why even identical twins have different finger prints.0704

On to the dermis, the dermis is the middle layer of the skin and a lot thicker than the epidermis.0712

This is where you have all the stuff going on anatomically and physiologically from deeper in terms of0720

blood vessels and neurons coming up to your skin to allow you sense your environment.0727

The middle layer of skin has lots of cells and what you have here is blood flow.0734

Here is a little reminder of what we are looking at and I am going to explain in a bit what this is.0740

This is the epidermis down here we are talking dermis and finally deep to that you will see subcutaneous layer.0755

You are going to have capillaries coming up to this area.0765

Once oxygen is given to all these cells you will get blue blood and that will go back the thicker veins that are much deeper.0768

Here is a small artery down here that is feeding the more superficial layers.0779

Here is a small branch and this is a capillary you are going to have oxygen and nutrients being given to all these cells here.0790

Like I have mentioned before capillaries will go all the way up to the stratum basale but not protrude in the epidermis.0797

That is why you were cutting vegetables and the knife slipped and you expect blood to come up but it never did it is because you just severed this part of the epidermis.0805

You did not end up cutting through capillaries and blood vessels.0818

If the cut is deep enough you are going to cut through millions of capillaries that you will find in your integumentary system.0822

Blood flow into the dermis is important for feeding the dermis and the superficial layers of the epidermis.0830

Hair is the next one.0838

We are going to draw little hair shaft coming out of here.0842

We will say it is a dark hair.0847

The hair shaft is the actual is the hair that is generated by the hair follicle.0854

The follicle is this whole thing that includes the cells that helps produce a new hair if this hair shaft comes up.0864

The average person loses about 50 hairs per day mostly from the head.0872

If you are losing a 100 or 200 per day you maybe heading towards baldness before someone else0877

because the rate that you produce new hairs underneath these hair shafts has a lot to do with genetics and nutrients.0884

Feeding this follicle you will have little capillaries coming in and feeding these cells that helps produce hair shafts.0893

It is true that hairs are mostly dead.0903

When we are talking down here at the root it has blood flow and cells are nourished but as cells0906

are pushed higher up all these cells or apex or going to be entirely dead cells.0912

The outside of the hair is known as the cortex.0924

The inside is the medulla.0926

Those terms are going to come up later on in lessons as well.0928

Follicle this entire thing and the hair shaft is the specific hair that is produced within the follicle.0931

The first gland that I am going to mention has something to do with hairs.0940

You are looking at the sebaceous glands here.0946

Sebaceous glands are made up of glandular epithelium and sebaceous help produce and secrete an oily substance that helps nourish the hair.0949

If it was not for your sebaceous glands your hair is would not be as healthy.0962

If you have not washed your hair or used shampoo for a while you are going to get a greasy look in our hair because of that extra sebum that is produced.0966

Sebum is what is secreted by the sebaceous glands.0976

Sebaceous gland is associated with hair follicles and secreting oily substance in the hair shaft.0984

Sweat glands there are couple of different kinds, the ecrine and apocrine.0992

The other nickname you are going to see for ecrine glands is merocrine glands.0999

Apocrine glands they are actually other kind of merocrine when they are first discovered scientist thought that1006

they are producing apocrine secretions but turns out they are producing merocrine ones.1013

Since enough that is written and enough studies have been done that is why they kept the name the same.1018

If you are wondering what merocrine glands are, that is mentioned I lesson 2 on tissues.1025

Ecrine glands are scattered all over the body.1030

Let me show you what they look like1033

Just like hair shafts going through the pores on the surface of the skin, sweat glands do as well.1036

You see like this crazy bundling of the sweat gland material here.1043

The interesting thing is if you took a single ecrine sweat gland and you unravel the whole thing they are pretty long in terms of length but they are tightly coiled.1051

The production of sweat in the tubes here and sweat gets secreted when needed.1061

Ecrine glands is mostly associated with heat regulation in terms of getting rid of water which is a way to cool down the body.1067

Ecrine glands are found all over the place especially the palms, bottoms of feet, forehead, neck, places you tend to sweat when your heart rate goes up and body heat goes up.1075

Ecrine mostly have to do with regulating your heat level in your body and getting rid of some waste products.1088

Apocrine is a bit different.1095

Structurally they look similar but they tend to be activated in puberty and they are associated with the armpits, around the nipples, and groin region.1097

Secretion from apocrine glands it is going to happen when your body heat goes up but there is a correlation with puberty than the implication of that.1108

There are theories that humans are secreting feromones to their apocrine glands.1119

Feromones are those airborne chemicals that attract the sexes to each other.1123

If you fall in love with someone at first sight and they are not your normal type that you are visually attracted to,1133

it might be the pheromones from their body that you brain notices on and unconscious level.1141

Pheromones are fascinating.1150

Those are more associated with apocrine sweat glands.1153

Arrector pili muscles which is arrector meaning stand straight up and pili muscles has to do with the hairs.1156

Here is an arrector pili muscle and it is not considered as a skeletal muscle because it is not connected to the bones and you do have conscious control over these.1170

The arrector pili muscle is associated with the hair shaft like I have mentioned before with your pores closing and the hair standing straight up.1180

It is your arrector pili muscle contracting to do that.1187

That is the process of closing a pore and keeping heat inside your body.1190

Speaking of hairs, there are 2 main kinds of hair found in the body.1194

They are vellus hairs and terminal hairs.1197

Vellus hairs are those little fuzz hairs you find all over the body.1213

If you look closer on my forearm I see this little whitish here all over the place.1218

Right here on my hand I see them scattered all over the place.1224

Those vellus hairs are the light ones that we do not notice very much but they are all over the body.1228

Typically you will see them on the palms, bottom of your feet, eyelids, and on your lips.1233

Terminal hairs are the darker ones.1242

Even if you are blonde they tend to be darker than the vellus hairs.1246

Those tend to be more concentrated on the head, armpits, pubic region, depending whether you are male or female and hormone levels.1251

You are going to see them elsewhere even on the forearm.1259

Vellus hairs all over the body and terminal not quite everywhere in the body but you do have a lot of them especially on the head.1263

Speaking of vellus versus terminal, there is a misconception that a chimpanzee or an ape has way more hairs than us.1271

They are close to same amount because even though at first glance it looks like humans has a lot less hair1279

if you add up all the vellus and terminal hairs we have a lot too.1286

The vellus hair is not just as visible but they are scattered all over the body.1291

Our hair compared to ape is not just as thick and not as long in general.1295

Since we are mammals, nails came from our mammalian ancestors.1301

Here is a top view of a nail.1314

Here is the lunula it is named after the fact that it looks like a crescent moon.1319

The white part that you see in the thumb this is located right next to the root of the nail1331

which is covered by parts of your skin so you cannot quite see the parts that are helping to make your nails.1334

There are always mitosis happening here that is why you have to keep cutting your nails.1342

The lunula just has some extra shielding that you cannot see the blood flow that is why it looks white.1346

The rest of your nail if you press down on it you can see that pink look that goes away temporarily because we are squeezing blood underneath the nail plate.1354

The lunula on the average person is not on every finger.1367

It is not visible on every finger.1370

On me I can see my lunula on my thumb but not on the rest of my digits.1372

Some people you cannot se them at all but it is rare.1376

The nail bed is what the actual nail itself is resting on and the nail plate is this highly keratinized super hard part known as the nail.1381

The side view here is looking like that.1393

The nail bed would actually be that nourishing part that is underneath it.1402

You are going to have blood flow to the nail bed and the nail plate itself is that looking down on it and this.1412

Here is the nail plate itself.1420

Cutaneous receptors are the last major item that you are going to see in the dermis.1425

They are nerve endings allowing you to notice the stimuli that are coming to your body.1431

Whether it is touched, some of them response to touch, pressure changes, even biometric pressure changes in the atmosphere could have and impact.1438

It is also pressure changes in terms of feeling pressure on you.1449

Humidity the amount of water vaporizing the air is going to affect certain nerve ending in your dermis.1453

The heat that is being experienced is going to correspond to the activation of the ecrine glands.1463

If you have been cut you are going to feel pain and it is going to be registered on the brain.1471

Chemical changes having certain chemicals heat may cause allergic reaction.1477

Even if you do not get an allergic reaction the cutaneous receptors are going to respond to that.1482

In addition to these parts of the dermis, you are going to see a lot of connective tissues scattered through out the dermis,1487

anchoring these particular tissues and keeping it arranged.1492

In the subcutaneous layer, the deepest level of the skin and this part right here you got mainly connective tissue.1497

This specific kind of tissue are for fat storage, adipocytes, this means cells that store lipids.1508

It is your adipose tissue.1516

Depending on what part of body you are in, the actual adipose storage will vary.1518

The place like your eyelid not have a significant amount of adipose tissue but a place like your rear1522

or buttocks you are going to have a lot more adipose storage in the adipocytes.1530

You are specifically storing fats or lipids in these little yellow lumps.1537

Blood flow is obvious here you can see vein and artery.1542

You also have lymph vessels and you are going to hear about those in the lymphatic system or your immune system.1546

You have those major arteries much deeper even deeper to the subcutaneous layer.1556

Major arteries feeding the arm like the brachial artery and vein, they are going to branch into tinier arteries that will feed those superficial layers.1562

When you watch the blood vessel lessons you are going to see that vein tends to be more superficial to arteries and that helps regulate your heat levels in your body.1571

Blood flow and branching into these tiny blood vessels is what you would find subcutaneously.1582

Cuts and healing,1591

Cuts happen, sometimes you are going to get a scar other times you do not.1594

It depends on how severe the cut is.1600

There are 4 main steps in terms of healing that cut and preventing you from bleeding out and dying from blood lost and getting the skin to as normal as possible.1602

First one is inflammation.1613

Let me draw a picture for you.1616

Here is the epidermis and here is the dermis, because the cut has gone to the dermis you are going to get bleeding because you cut into the blood vessels of the dermis.1618

Blood pours in.1644

The first response to getting a cut is of course blood is going to pour in there but inflammation happens.1648

The blood vessels that are physically feeding the dermis are going to be stimulated to expand.1666

It sounds ironic because you got blood coming out why do you want to expand?1677

Your body wants to get more white blood cells and other cells that are going to help protect this area and regenerate it.1681

Getting more blood flow to this area through expanded blood vessels is a part1688

of the inflammatory response associated with your immune system and cardiovascular system.1693

You are going to have inflammation occurring and mast cells are going to be stimulating that.1698

Mast cells are kind of connective tissue that are going to secrete histamine which causes the inflammation occur1706

and heparine makes new blood and make it not clot.1713

You are going to be clotting this area because you do not want to be bleeding out continuously.1719

After a few hours you will get migration but the exact amount of time depends on how significant this cut it depends on the size and width.1726

That is inflammation.1737

What is migrating?1739

You are going to get certain fibroblasts migrating to this area.1740

Let me draw fibroblasts.1747

I am going to raise some of these.1749

As your blood vessels form little clots, the amount of blood coming to this area is going to be reduced so that less blood will be coming out of the wound.1756

You are going to get fibroblasts secreting connective tissue fibers to help rebind the areas that have been separated.1775

What is migrating here is fibroblasts.1785

They are coming to that area and helping out here.1788

You are also going to get phagocytosis happening.1790

Phagocytosis means cellular eating and what is doing the cell eating is called macrophages.1794

Macrophages are bigger cells that are going to be eating up cellular debris, the damaged cells from the particular laceration or cut.1807

The little bits of blood cells that they come across that have been leaked space.1821

As those clean up the debris through swallowing up that stuff you are going to get these fibroblasts secreting fibers and helping reconnect this area.1826

Fast forward in a few days, we are going to get proliferation.1838

You are going to get a scab after a few hours.1843

That is part of the clotting blood exposed to the air that is dried out and it is a nice shield for what is going on under this.1852

If you pick of a scab prematurely it is harder for your body to heal and you are more likely to get a scar if you keep on picking on scab.1863

You are going to get what is called proliferation next.1871

There is slightly less of this clotted blood here but what you are going to get is continued fibroblasts production,1875

getting continued connecting together of these damaged parts of the skin by secreting those collagen fibers.1887

You are going to get increased fibroblasts and the amount of phagocytosis is going to be1894

reduced significantly because you already cleaned up most of that debris at this point.1902

Maturation at this point the scab is gone and hopefully not a scar.1908

Often times when it fist heals, what is remaining after the scab falls off sometimes is a little bit indented1919

but as you get continued maturation of this newly formed area of skin sometimes it will get pushed up a little bit more as time goes on.1931

The scar is a little bit less visible as time goes on1945

Some people call it kelloids which are elevated scars even with tiny cuts and we think there are genetic factors associated with that.1948

These are the 4 main ways that you heal a cut and prevent yourself from bleeding out.1956

Another main issues of the skin are burns.1962

They are not just caused by fire or heat.1967

That is the main way that burns are cause but chemical burns can happen.1969

Strong acids that hit your skin like base and alkaline can harm your skin.1974

Electricity burns getting shocked by electricity or lightning, that is going to cause a burn and not just the skin but also the internal organs and can be fatal.1981

Friction whether it is a rug burn or blister has developed from lifting weights without wearing gloves or swinging a bat, those were friction burns.1994

I have a friction burn on the bottom of my feet because I have been walking around in sandals2002

and yesterday I have walked around 10 miles in sandals and walking briskly.2010

When I was done I have a blister on one of my foot because so much rubbing and inadequate support and cushioning caused a second degree burn.2016

I will tell you more about that momentarily.2027

First degree burns and we can really say there are 4 degrees of burn.2029

1st degree if burn is primarily affecting the epidermis.2034

Most classic one would be a sun burn.2038

Those heal quicker because if you are just burning and harming your epidermal cells they are very easily replaced.2043

You are constantly shedding them and you are not damaging any parts of the epidermis.2053

Typically a sun burn goes away within a few days or a week.2059

It depends on the severity of the sun burn.2063

Also you can get a minor heat burn not from the sun or minor friction but also can be considered a 1st degree burn as long as it does not penetrate the epidermis.2065

Next up is 2nd degree burn is harming not only the epidermal cells but also the dermal cells.2075

It could be a severe sun burn or hot water spilled on you.2084

It could be a friction burn.2090

Often times it is not just redness associated with second degree burn but blisters are waxy like can appear.2092

Blisters a very common because think about how many fluid filled little chambers there are2100

in the dermis, not only blood vessels but also sweat glands.2106

In those tissues get damaged pulling the fluid in form of blisters and takes longer to heal.2108

3rd degree burn can be more fatal depending on how extensive the 3rd degree burns are that is getting down into the hypodermis.2117

Like getting burn with fire, getting such a bad chemical burn that damaged the epidermis to the hypodermis all the way down.2128

You are going to require skin graphs typically because if you damage all the dermis that is where2136

all these major tissues are housed and you can not easily get those back once you damaged them.2143

Damage down to the hypodermis is permanent but skin graphs from your own body or skin from a cadaver.2148

They will give you drugs to calm down your immune system so you can accept that skin from a cadaver if it is from another body.2161

The danger of a 3rd degree burn is if you do not get a skin graph quickly the chances of infection is very high.2169

Think about all of the protective parts that you have lost because of that 3rd degree burn.2176

Somebody who have a 3rd degree burns over their body is very susceptible to infections.2181

4th degree burns I do not know those existed until about a year ago.2186

It is a term not used often because you rarely see them but that is damaging even down through all of the hypodermis down to the muscle or bone.2190

Those are incredibly fatal if they are over a lot of the body.2202

In terms of burns with communicating quickly and adequately between emergency and paramedics and hospital staffs2208

you are going to find nurses, surgeons, doctors, there is this rule of 9 that is interesting2218

in terms of approximating how widely distributed the burn is on the surface of the skin.2225

Someone figure out the percentage of skin covering the body relative to the areas that it is on.2229

They came up with the rule of 9.2236

Let us say somebody burns all of an arm, an entire arm is burned 2nd or 3rd degree.2238

All of this is 9% approximately and that is the entire thing.2247

Both arms together, if you burned just the arms in their entirety you burned 18% of your skin.2251

Burning from here down is 4 ½ % or 5%.2258

Each arm is about 9% of your skin.2266

The legs if you think about it they have twice as much skin on average because they are longer and thicker.2269

A leg is actually twice as much skin as an arm.2279

If you burn just half of leg that is 9%.2285

If you burn the bottom half of both legs that is 18%.2292

If you burn all of both legs that is 36%.2297

Your torso as a whole, the chest and parts of your pelvic area that is about 36%.2302

Burning all of the front of your chest, the ventral portion or anterior portion of your chest is 18%.2315

Burning just the back is 18% and the whole thing will be 36%.2323

The entire head, all of your head is going to be 9% approximately.2328

If you burn all of your face you can say 4 or 5%.2338

The perineum is the part of the skin associated with the groin area.2342

It is only 1% not much of your skin but it is the exception to this rules of 9 in terms of multiples of 9.2351

If you add all of this 9 × 2, 18 × 2, 36 + 9 + 1 you will get 100% of your skin.2359

This is a way for a paramedic to quickly communicate with the ER that they are taking this person for surgery and skin graphs.2372

It enables them to quickly prepare on how severe this is.2381

Let us say we have a person with 9% of their body burn with 2nd degree burns that is not severe.2386

But if we say 3rd degree burns on 45% of their body that is more severe.2394

That is how the rule of 9 is applied.2399

For some skin conditions and disorders, we have mentioned scars a little bit earlier and how cuts heal but this one is a kelloid, this is an elevated scar.2401

It is not common but some people get them wherever they get cut there is an elevated scar2414

from additional production of your fibers in skin cells in response to the cut.2421

The average scar is a remnant of where you had a cut and depending on how wide or deep it is2429

you are likely to get a permanent mark that your skin could not repair to look like before.2436

The thickness of it has to do with it because a thick and deep cut and the reason they tell you that you need stitches2444

it is because by binding together where you get the cut it is helping the skin produce collagen2452

and connective tissues to get it back together and heal effectively.2461

A deep wide cut without stitches is going to make a more severe scar once it is done healing.2465

Moles tend to be elevated but not always, extra melanated part.2471

Let me draw a mole.2481

A mole can look like that.2483

The darkness of it varies on the person.2484

Some moles will be the exact same color surrounding the skin.2487

Other will be a little bit more melanated.2491

The difference between a mole and a freckle is a mole tends to be a very concentrated, smooth, circular edge2494

on terms of how the melanocytes on the area are producing that extra melanin.2501

A freckle is not elevated and tends to be more random in terms of how they are produced.2507

The occurrence of freckles has a lot to do with genetics.2515

Some people are born with more freckles than others and extra exposure to UV radiation from the sunlight can make the freckles more obvious as well.2519

A birth mark tends to be a bunch of freckles together in one area.2527

Some people are born with birth mark on the face, or on the back.2535

I was born with a birth mark on the back of my neck and as I grew it stretched as my skin grew and my body grew in size.2538

It stretched out so thinly now you can hardly tell it is there.2548

When I was a baby it was a bit darker and smaller.2552

Some birth marks do stretch out but others are darker and more permanent as you where to surgically get rid off it.2555

Melanoma and carcinoma are forms of skin cancer.2563

Melanoma as you can tell form the melano part has to do with melanocytes.2567

Those cells that produce melanin in the deepest parts of the epidermis if too much radiation from the sun2572

or other source has damaged the DNA there they will grow out of control.2579

It is when like a mole starts changing in terms of the border.2584

They usually say A, B, C, D in terms of how it develops.2589

If it is A symmetrical the mole starts looking not like a perfect circle that could be a problem2600

if it starts looking like jagged edge on one side and nice round on the other, that is sign it is growing out of control and maybe home to some cancerous cells.2611

If the border of it is not nice little circle, that is sign that it is not doing so well.2620

If the color is off, if one part of the mole is darker or lighter than other part that is a sign that part of that related to the melanocytes underneath might have cancer cells.2630

If the diameter of the mole starts changing in size meaning it is growing actively and obviously, if any of these are true go to a skin doctor and get it checked out.2646

They will take a biopsy and see if it is cancerous.2654

Treating melanomas early is what is going to save your life because melanoma is the most deadly form of skin cancer.2663

Get it taken care of.2670

Carcinoma not as deadly, the basal cell carcinoma is a common type.2672

They tend to not to look as dark but once again it is cancerous cell developing at the base of your epidermis.2677

That carcinoma is also from too much sun exposure over a period of time.2686

Carcinoma will be a little section that looks like it does not belong there.2691

Over a period of time you will notice it is growing in size and looking darker over time get it checked it out.2698

It is not quite as deadly but if either of these spread in your lymphatic tissue meaning in your modified blood vessels that has to do2707

with your immune response then the cancer cells can migrate into another vital organ and that can result in death.2714

Acne is not just in teenagers or people going to puberty but adults can experience acne as well.2721

There is a misconception that it is related to dirt or bacteria.2728

Sometimes that has to do with acne but there are some genetic factors and hormones that have a lot to do with acnes.2733

Some people will keep their face extremely clean on a daily basis but still they get acne.2739

Puberty and hormonal changes can trigger acne on the face, on the back, parts of the chest2746

but keeping your face and body clean is going to minimize the chances of acne happening.2754

If it is related to bacteria the way it happens is bacteria getting into one of the pores in your skin causing inflammation2761

and migration of white blood cells into that area to eat up the bacteria that is dividing and that is how you get little white head or pus forming.2768

This is kind of disgusting but also fascinating.2778

The little pus is dead white blood cells that sacrificed their lives to protect you from that bacteria.2781

They do recommend that you do not pop a pimple because you are popping a little bit of capillaries under there.2790

You are more likely to have a scar in effect if you do that a lot but acne often times will subside.2800

It would not be as apparent or wide spread when someone transitions into adulthood.2807

Sometimes when I shave I do get little pimples and that is because the razor has cut off2813

some of those superficial skin cells and allowed bacteria go into my pores easily.2820

Keeping your face clean is going to help a bit out with acne but they are genetic factors associated with it.2828

Warts come from a papilloma virus.2834

HPV, DSTD is a different term of how it is spread but warts in general contact with someone else skin2839

who has a wart could allow the virus to hop into your skin and into your blood stream.2851

Warts sometimes you will have them over a period of time.2857

I had a wart for a while on my hand in high school now I do not have them and I have not produced them for years.2860

What happened was the wart right here I went to the dermatologist and they froze it off.2867

They had a cold material killed the cells that have the wart virus in it down to the root and eventually fell off.2872

If I still have the virus in my body it is dormant because wart is caused by this virus and it definitely manipulates how skin develops in that area.2882

Wrinkles, when someone ages their strength and stability of the collagen that is producing is not quite as strong.2893

It is a little bit more saggy and weak and that kind of less young quality of how well you are able to produce collagen is what makes wrinkles.2901

The amount of sun exposure you have can impact them and you will get little spots where2913

the wrinkles you get from getting expressions and in this area can enhance that look on how collagen is less tight.2922

Psoriasis, eczema, rosacea, all are similar to each other but there are some differences.2933

With all of these you will get inflammation consistently.2939

These are disorders associated with the skin in terms of extra inflammation, itchiness, irritation, and redness.2944

Psoriasis, the sign of that is excess production of flaky skin.2951

One of my professors in college said that her husband had psoriasis severely2957

that she would find giant flakes of skin on the couch or rug that her husband has shed.2963

He took medication to lessen the negative effects but there is no cure.2970

A store cream or medication that can reduce the look of psoriasis.2976

Eczema and rosacea definitely redness and irritation.2981

Rocasea tends to be on the face mostly.2985

Eczema comes and goes.2991

People who have eczema breaks out then it will go away but it is something that lasts.2993

Sometimes infants will have eczema for a little while but as they age they will not experience it quite as much.2999

Vitiligo is the death of melanocytes in terms of them completely being inactive not making melanin anymore.3008

People think of Michael Jackson with this but almost anyone can get it.3017

They think there are genetic factors associated with it but there could be environmental triggers as well.3024

One example is I have a relative who is on a certain of a cholesterol medication3029

and one of potential side effect was bleaching of the skin meaning causing vitiligo on part of the body.3034

She took this medication for months and noticed that she started losing pigment in her hands and finally stopped when it crept down here.3041

To this day her hands are completely bleached and the rest of her body looks tan.3050

She had complete destruction of melanocytes and she is not going to get it back.3057

A medication can cause vitiligo.3062

It is not just genetic factors.3064

It causes bleaching of the skin and once you are not making melanin you are not going to get skin pigment anymore.3066

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