Anatomy and Physiology of the Skin, Animation

(USMLE topics) Structure of the skin, layers of the epidermis, skin barrier and pigmentation.
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Voice by: Ashley Fleming
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The skin covers the body and protects it from the external environment. It also prevents water loss, provides sensory function, plays a role in body temperature regulation, and is the site of vitamin D synthesis.
The skin is composed of 2 layers: the outer epidermis and the deeper dermis. The dermis is connected to underlying structures via a subcutaneous tissue, the hypodermis, which is not technically considered part of the skin.
The epidermis provides barrier and protection, it consists mainly of the protein keratin, a tough and water-insoluble structural protein.
The dermis constitutes the bulk of the skin, it provides support and flexibility. The dermis consists mainly of collagen, and to a lesser extent, elastin fibers. Loss of collagen and elastin, such as with aging, causes the skin to slack. The boundary surface between the epidermis and dermis is not flat but wavy, meaning the 2 tissues interlock, strengthening their connection. With age, this boundary flattens and the skin becomes more fragile. The dermis is well vascularized and contains sensory nerves, hair follicles, sebaceous glands and sweat glands. It has 2 zones: the upper papillary dermis with loose connective tissue, and the lower reticular dermis with denser connective tissue. The dermis houses immune cells and allows inflammatory response to activate upon exposure to invading organisms.
The hypodermis is composed of loose connective and adipose tissues. This is where most of the body fat is stored. The hypodermis provides thermal insulation, padding and serves as the body main energy storage.
The thickness and proportion of the epidermis and dermis vary greatly depending on their location on the body, but the skin is classified as thick or thin based on the thickness of the epidermis alone. Thick skin is found only in areas where there is a lot of abrasion: palms, soles, digits; and has 5 epidermal layers. Thin skin is everywhere else and has 4 epidermal layers.
Most cells of the epidermis are keratin-producing cells, or keratinocytes. New cells are constantly produced by mitotic cell division in the basal layer. They then move towards the skin surface as they age and differentiate, changing shape, from cuboidal to flat. The distinct epidermal layers represent different stages of keratinocyte differentiation, from their birth to their death.
The spinous layer is characterized by presence of abundant desmosomes which connect keratin filaments of adjacent cells, anchoring them together, providing resistance to physical stress.
The granular layer is loaded with keratohyalin granules. These granules release several substances that cross-link keratin filaments, converting them into an impermeable keratin matrix. This process is known as cornification or keratinization, the result of which is the most superficial layer, the cornified layer, about 30 cells thick. These fully keratinized dead cells form the skin barrier. They are shed periodically from the surface as new cells are moving up. The entire epidermis is replaced every 30 to 40 days. The renewal process becomes slower with age but faster in injured skin, when cell proliferation is accelerated for wound healing.
The epidermis also contains immune cells, touch sensory cells and melanocytes. Melanocytes produce the pigment melanin and transfer it to keratinocytes. The amount of melanin produced is the major determinant of skin color. Melanin synthesis is stimulated by UV light and is thought to be a protective mechanism against UV radiation damage.

[@Alilamedicalmedia]

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[@yeboahrebecca9571]

1

[@SilenceInTheBliss]

Gettin' the job done in under 5 minutes. You are a goddess.

[@umutkaratekin4662]

Thanks for brilliant explanation about our skin. Lots of love from Turkey.

[@Alilamedicalmedia]

Glad it was helpful!

[@itsmatthewalvarado]

This is such a great clip for me at the moment! Thank you for putting it together and presenting in a digestable form.

[@suebeawho6537]

Me too

[@franciscocasas5897]

This is really helping me prepare for my anatomy exam, thanks!

[@vanessankcellnobtchute9120]

I love those animations, so BEAUTIFUL!

[@umeyyeyazicioglu66]

thank you for this video. it was enjoyable to watch...to meditate on the incredible amount of care and wisdom in the design of our skin

[@petersilwimba1013]

This video is educative and help in understanding of the skin function

[@powerbrain840]

the epidermis looks the most cleanest of all of the layers of the skin.

[@meghasa8416]

It's so beautiful :) Thank you very much 💜

[@abdifatahfarahhamud6426]

Your videos are very amazing !!! Good job guys 👏

[@abcd0038]

I am very clear with this skin structure which i confused while studying tissue level of organisations.

[@Beautifullife_7]

I am starting my Asthetics program in three days and want to be ahead of the game.

[@alexirom3834]

Hello creator, we are all grateful to you, for your beneficial efforts for us. One thing i have need to ask kindly mention the level on your lectures like for which classes it is for, it will create an ease for us.

[@Alilamedicalmedia]

Hi, most of our videos cover the basics. Only the "ECG/EKG" playlist is more advanced.

[@alexirom3834]

@@Alilamedicalmedia i am student of Matric class, does this video perfect for me or should i go more advance?

[@Alilamedicalmedia]

At any level you will need the basic first, then you may need more. Moreover, our videos do not replace your lectures/books, they only help you understand your lectures better.

[@alexirom3834]

@@Alilamedicalmedia ok thanks for your precious time.

[@almasakic1148]

This was so helpful as I'm studying the physiology of skin for my CSI friction ridge lessons!

[@tooba5182]

Great job

[@tooba5182]

🎉

[@abisolaoyewumi6497]

Thank you

[@radheyshyamsharma5074]

Helpful video for students with short and understandable.

[@ryanjackson3539]

I have a question. What are these almost cotton like fibers you can pull out of your skin under the top layer? I notice them while trying to remove a cyst like ball from skin with tweezers but missed and it just pulled at the skin in the wound and out stretched these fibers. I tested it on a different spot by breaking the skin and pulling at the area with tweezers again and i kept pulling out these fibers that sometimes seemed like a layer of transparent like film before breaking off.

[@suebeawho6537]

May I barf now? Lol Yikes!

[@MelodyMwiinga-ov9rw]

This is so helpful guys

[@nguyenhongsonnnguyen7360]

I would like to ask, does the skin in sensitive parts such as the lips and genitals have a natural skin turnover cycle like skin elsewhere?

[@MAX_TV99]

Beautiful ❤❤❤Thank you so much 🙏🏽

[@madhurimadhar7735]

Thank you so much it's very helpful video ❤😊

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Admirable

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This disease is curable or not? Because iam suffering from this disease what should I do for this solution plz help 🙏😣😣

[@vdr4849]

Thank You excellent Video 🙏👌

[@nsg2425]

What is the average distance of subcutaneous layer from epidermis❓

[@mohanoorislam7696]

please make more video like this on newer topic

[@karencanaviri1173]

Wonderful

[@JavanKibet-lv7kw]

SHORT AND SWEET

[@sandratogneri9982]

In my NVQ 3 ....I studded Pressure Areas ....Amazing the Skin .... It Can Break Down in Such a Short Time ....XXX A Lovly Millary Trand Nurse Tought me as well are Others with my Studies...but Wow did she make it interesting XXX ♥️♥️♥️

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My eyelids are not fully closed, and I need to extend the levator muscle of my upper eyelid. Where can I buy materials for human fascia? And I need materials that are not rejected by the human body to replace the levator muscles. I don't want to take my own materials. I am afraid that it will damage my human body and leave scars.

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great info

[@salonisoni5027]

I am watching every video. But plz provide in hindi also. Your animations and way of speaking is really perfect.

[@Alilamedicalmedia]

We dont know Hindi. We rely on our viewers to provide subtitles in other languages.

[@salonisoni5027]

If you will try it in hindi I am very sure that your subscribers will be double and more. I share these videos with my friends but they say that these are in high tech English and they are unable to understand so they wouldn't watch.

[@Alilamedicalmedia]

You could help translate and add subs in Hindi :) Our videos are translated by people like you, for their friends. Thank you in advance!

[@VidarrKerr]

@@salonisoni5027 We all have to learn English now, whether we want to or not. It would be useless to study medicine and science without knowing English. All of the leading research and work and publications are in English. You won't know any of it without English. You also will never be able to publish anything, if you even make it that far.

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Awesome❤️

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Nice

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Good

[@ramendrakumar6329]

Then where is epithelial tissue is found?

[@Pathologyformedicalstudents]

Epithelial tissues line the outer surfaces of organs and blood vessels throughout the body, as well as the inner surfaces of cavities in many internal organs

[@alexismarquez3674]

ASSESSING THE SKIN: BY COLOR, POSSIBLE CAUSE, TEMPERATURE/MOISTURE AND POSSIBLE CAUSE - 1. PINK - NORMAL COLOR, WARM, NORMAL CONDITION; 2. ASHEN/PALE FACE/SKIN/SKIN ON EXTREMITIES - HYPOVOLEMIA/HYPOXIA - HOT (TEMPERATURE/MOISTURE), - FEVER, SUNBURN, HYPERTHERMIA, HEAVY EXERCISE AND SWEATING, 3. GRAY BLUE (CYANOTIC) - INSUFFICIENT GAS EXCHANGE HYPOXIA - COOL (TEMPERATURE/MOISTURE), EARLY SHOCK, HEAT EXHAUSTION (POSSIBLE CAUSE), 4. FLUSHED - HIGH BLOOD PRESSURE, CARBON MONOXIDE POISONING, SIGNIFICANT FEVER, HEATSTROKE, SUNBURN, ALLERGIC REACTION, COLD (TEMPERATURE/MOISTURE), PROFOUND SHOCK, HYPOTHERMIA, FROSTBITE (POSSIBLE CAUSE), 5. JAUNDICE - LIVER DISEASE OR DYSFUNCTION , DRY, CLAMMY, DAMP OR MOIST (TEMPERATURE/MOISTURE), NORMAL CONDITION/SHOCK -, POSSIBLE CAUSE . ASSESSMENT SCALE FOR PITTING EDEMA IS ALSO IMPORTANT ❤️ (LEVEL/DESCRIPTION). - 1+ - SLIGHT PITTING, NO VISIBLE DISTORTION, DISAPPEARS RAPIDLY, 2 + - SOMEWHAT DEEPER PIT THAN 1 + , NO READILY DETECTABLE DISTORTION, DISAPPEARS IN 10-15 SECONDS, 3+ - PIT IS NOTICEABLE DEEP, MAY LAST MORE THAN 1 MINUTE, DEPENDENT EXTREMITY LOOKS FULLER AND SWOLLEN, 4+ - PIT VERY DEEP, LAST 2-5 MINUTES , DEPENDENT EXTREMITY GROSSLY DISTORTED. - THE BODY MASS INDEX (BMI) - BMI = WEIGHT (KG)/HEIGHT (m)2 OR BMI = WEIGHT (lb) x 704.5/height (In)2 - BODY SURFACE AREA (BSA) - √Ht (cm) x Wt(Kg)/3600 or Ht (in) x Wt (lb)/3131 - WAIST TO HIP RATIO - RATIO = WAIST MEASUREMENT/HIP MEASUREMENT.

[@dylanziesing6122]

Underwear is part of the Skin Layer? Lol.

[@powerbrain840]

yeah, it was better to take off those two, so we can understand and concentrate a bit more well,

[@muhammadafrasiab9188]

Poor thinking

[@maureengardiner3627]

Get the joke but it’s kind of a dad one. You keep doing you though❤

[@infirence]

😂😅🤣 nice

[@Moni_ma009]

What you expect bruh 😂😂

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eyw 🙌❤

[@sandratogneri9982]

Finger toes .....need to be protected...especially if you have Diabetes...careful if testing the blood XXX

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Woah

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👌👌

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❤️❤️❤️

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Hi

[@thomasfields7902]

And the times of this ignorance God winked at; but now commandeth all men every where to repent: (Acts 17:30) The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance. (2 Peter 3:9) And as it is appointed unto men once to die, but after this the judgment: (Hebrews 9:27)

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*ahem* B E A N S

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gross beans

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I am.

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