Sistema tegumentario

The Integumentary System

Epidermis - keratin (epithelial tissue)

• cellular types: keratinocyte, melanocyte, langerans, merkel
• stratum: corneum, lucidum - thick skin, granulosum, spinosum, basale

Dermis - collagen, elastine (connective tissue)

• blood vessels, nerv fibers, hair follicles
• papillary layer, reticular layer

Hypodermis: subcute

• adipoise cells

Skin, hair, nails, oil glands, sweat and mammary

Functions:

1. protection - against infection and extreme temperatures with barrier,
2. excretion
3. synthesis vitamin D - solar light through liver and kidneys (calcitrol) -> vitamin D
4. maintains body with the balance of fluids
5. blood storage - 5% of blood is retained in skin
6. sensation

insensible perspiration -> 1/2 L

sensible perspiration -> fino a 12 L

• cyanosis -> blue skin
  • may indicate heart failure
  • poor circulation
  • severe respiratory issues
• jaundice -> yellow skin
  • may indicate liver disorder
• erythema -> red skin
  • fever
  • inflammation
  • allergy

The Integumentary System

oponi sensoriali neurom sensoriali raccolgono stimoli ambientali centro d'integrazione (encefalo, midollo) nervi motori risposta organi effettori

periferia SNP SNC (scatola cranica, encefalo)

Epidermis

• keratin (epithelial tissue)

cellular types: keratinocyte, melanocyte, langerans, merkel

stratum: corneum, lucidum -> thick skin, granulosum, spinosum, basale

Dermis

• collagen, elastine (connective tissue)

• blood vessels, ner fibers, hair follicles
• papillary layer, reticular layer

Hypodermis

• subcute

• adipose cells

Skin, hair, nails, oil glands, sweat and mammary

Functions

1. protection = against infection and extreme temperatures with barrier
2. excretion = rid waste and water
3. synthesis vitamin D = solar light through liver and kidneys (calcitrol) -> vitamina D forma attiva
4. maintains body with the balance of fluids
5. blood storage: 5% of blood is retained in skin
6. sensation

insensible perspiration -> traspirazione 1/2 L

sensible perspiration -> sudorazione fino a 12 L -> pneumopatia

• cyanosis -> blue skin
  • may indicate heart failure
  • poor circulation
  • severe respiratory issues
• jaundice -> yellow skin (itero)
  • may indicate liver disorder
• erythema -> red skin
  • fever
  • inflammation
  • allergy

la pelle grazie a una luce del sole sintetizza la vitamina D ma attiva, e nel passaggio dal rene e fegato si attiva diventando calcitriolo o calcitonina

Skin Appendages

• hair, nails, sweat glands, sebaceous (oil) glands

shaft = fusto del pelo -> keratinization is complete

root = radice -> keratiniation is not happening

root of nail -> parte viva

nail body -> parte visibile non cheratinizzata

nail bed

You've got up to 3 million tiny sudoriferous or sweat glands scattered throughout your body

Eccrine Sweat Glands

• palms, forehead, foot soles

You have about 2000 aprocrine glands they start corris _[corris?] around puberty

Ghiandole Sudoripare

• ECRINE (secernanon sudore acqueoso)
• APOCRINE (secernano sudore contenente sostanze con la presenza grassi e proteine)
• ingluine, ascelle
• ghiandole mammarie
• il latte è una specie di sudore secreto

Un essere vivente che ha pelo e ghiandole mammarie si chiama mammifero

Ghiandole Sebacee

• producono sostanze che rendono morbida ed impermeabile la pelle -> la pelle è acida (PH 5.5)
• così non ci vivono batteri e funghi
• sono associate al pelo

Look at all this stuff - soaps, lotions, conditioners, polishes, all from that huge section of your local store that's dedicated solely to the grooming of your skin, hair and nails. Some might see these things as the trappings of vanity , but me...I see them as the tools for the care, maintenance and sure sometimes decoration of the integumentary system. Now true, in spite of what the cosmetics industry may lead you to believe, your integumentary system is more than just a place to put eye-shadow and hair product in the hopes of attracting a mate. This collection of resilient tissues, ranging from the sharp and hard to the soft and fluffy, serve a whole panoply of functions, the majority of which you never even notice. But when you do notice what your integumentary system is doing, the results are often uncomfortable, or ugly, or both, and that is what this stuff is mostly for. Your sweat glands can make you smell, you oil glands can give you zits, your skin can become either scaly or greasy and in rare cases it can even change color. And hair...well, let's just say it takes a lot of science to tame this man! But each of these tissues, frustrating as they may be at times, has a purpose, and without them you'd be cold, and vulnerable, and...dead. I'm not gonna lecture you on personal hygiene today, but hopefully by the end of this you'll understand the important functions of your integumentary system, and maybe why it's worth a little bit of time and effort to keep it healthy. And hey...I might even score you a date!

01:21 protection

If you recall a recent run-in with rogue nails or tattoo needles, you probably remember that the first and most vital purpose of your integumentary system is to act as a protective barrier. Your skin, hair, nails and sweat and oil glands, all work together to shield you from all the things out there that are out to get you – excess of sunlight, infections, abrasions, and just...you know...getting poked by sharp sticks and stuff.

01:41 sensation

But beyond that, the system is also vital to how you sense the world around you. Your skin is loaded with structures that are largely part of the nervous system called cutaneous sensory receptors. They are what receives stimuli from the outside environment and send them to your brain. These receptors, or corpuscles as they are sometimes called, register all the different sensations that you associate with touch. Your tactile corpuscles, for instance, are what make you constantly aware of the tag that's scratching on the back of your neck, while your lamellar corpuscles register the sense of pressure, like when someone put their hand on your shoulder. Your hair follicles have receptors too, which is why you feel a slight breeze on your skin or through your hair.

02:16 excretion

Now on the less sexy front, your integumentary system also plays a role in the excretion of waste, though not as big as a role as we are often led to believe. Most nitrogen-containing waste — like urea, ureic acid and ammonia — are disposed off through your urine, but small amounts are eliminated through your skin in sweat. But despite what you may be told at the beginning of your hard yoga class, there isn't much evidence suggesting that heavy sweating actually rids your body of any extra toxin – say, if anything, you are just losing more water.

02:42 blood storage

When you do exercise though, you call on another of your skin's lesser known functions as a handy blood storage unit. About 5 percent of your entire blood volume is retained in your skin at any given time, and when you suddenly need more blood supply to your organs, like when you are working out, your nervous system constricts your dermal blood vessels to squeeze that extra blood into circulation.

03:06 temperature regulation

Now when it's time for exertion, both your blood and sweat glands work together to perform a key function regulating your body temperature. Even without exercising, your body oozes out about half a liter of sweat per day in an effort to keep you at a comfortable temperature. That's your normal, barely noticeable sweat, called insensible perspiration. But on a hot day or if you are on the dance floor exerting yourself, that sweat become much more noticeable. Such sensible perspiration could produce as much as 12 liters of sweat per day. Now if the temperature gets chilly, the surface of your skin can lose a lot of heat because it has so much warm blood behind it. To regulate that heat loss, your dermal blood vessels constrict causing your blood to head deeper into your tissues and help keep vital organs warm. When things heat up, those vessels in the skin gradually relax and allow that blood to return to the surface. You probably noticed that if you are cold for too long, your skin may lose some of its color or even turn pale blue if you are light skinned, as that blood retreats from the surface.

03:54 signs of poor health

And in facts like a Lightman's test for your body, changes in the color of your skin may indicate a number of homeostatic unbalances. Blue skin or cyanosis In Caucasian people may indicate heart failure, poor circulation and severe respiratory issues — that's because blood that has been depleted of oxygen turns darker in color, and when seen through the tissues of lips or skin, it can look bluish. A yellowing of the skin called jaundice usually signifies liver dis-

order, as yellow bile starts accumulating in the bloodstream. Reddening skin or erythema could indicate a fever, inflammation or allergy. All of these conditions cause blood vessels to expand and more blood to flow to the skin surface. Of course human skin color spans a pretty wide spectrum, so some of these conditions are easier to diagnose by looking for discolorations of other tissues, like mucous membranes and beds of finger and toe nails. 04:39 – melanin and vitamin D Synthesis

However light or dark your skin color is though, you can thank your melanin for it. You remember that melanin is a pigment produced by the melanocyte cells in your epidermis. Melanin has two forms producing pigments that range in color from reddish yellow to brownish black. Because its main job is to protect us from the Sun’s ultraviolet rays, it makes sense that in the distant past the distribution of these different skin tones was not at all random. Historically, where solar radiation is more intense, higher concentration of deep colored melanin became an advantage for the protection it provided. But closer to the Poles, where the solar rays are weaker and more diffuse, lower concentration allowed people to collect what sunlight was available to manufacture vitamin D, because of the fact that we all need some level of sunlight to hit our skin to survive. Your bones require vitamin D to keep producing new bone cells, and it’s the only vitamin that your body can actually produce in its own. Your skin cell contain a molecule that converts to vitamin D when it comes in contact with UV light. From there, the vitamin heads through your bloodstream to your liver and kidneys, where truly becomes activated D, also called calcitriol, which is circulated to all the bones of your body. 05:39 – skin appendages

(...) your integumentary system also involves your so called skin appendages – your hair, nails, sweat and sebaceous or oil glands, which can each be fascinating as well as frustrating in its own way. If you are like some people I know and you spend a fortune on hair conditioner; that’s because your cuticles are out of control. All your hairs or pili are basically these flexible strands of dead keratin protein cells like your fingernails. And the outermost layer of these dead cells, called the cuticle, looks like it’s made of overlapping roof shingles. So what you are paying the conditioner *to do is even out the rough surface between these cells of the cuticle to make it look smooth. Now if you pluck out a strand of your hair, you’ll be in pain, but you will also have the opportunity to notice the it has two main regions: the shaft, where the keratinization is complete, and the root, the part inside the follicle where the keratinization is still happening. Each follicle is just a tube of epidermal cells, and just like in your epidermis the cells at the bottom of the follicle are young and fresh and continually dividing and pushing older cells up through the skin and into the open air. And your finger and toe nails pretty much grow in the same way, starting at the back of the nail bed, where the new cells divide, at the root, and get pushed forward creating the scaly, hard keratin that you paint with polish and keep trimmed during the flip-flop season. But there’s probably no other part of the integumentary system that you spend more money on trying to control than your sweat and oil glands. You’ve got up to three million tiny sudoriferous or sweat glands distributed throughout your body. These guys secrete your salty, watery sweat and they come in two types, eccrine and apocrine. Your eccrine sweat glands are more abundant than the other – in your palms, forehead and in the soles of your feet. They are just simple coiled tubes that start at the dermis, extend through a duct, and open into a pore on the surface of your skin. Your apocrine sweat glands are a slightly different story. You only have about 2000 of these, and they start cooking around puberty, emptying into the hair follicles around your armpits and groin. These glands secrete a kind of deluxe sweat with fats and proteins, and it’s more viscous and sometimes yellowish in color. When bacteria on the skin get a hold of this sweat, it gets odorific, creating what we generally call body odor. Deodorants don’t affect how much you sweat, but they do reduce your smell by attacking the stinkmaking bacteria, while antiperspirants do the opposite, using ingredients like aluminum to block your sweat glands and actually keep you from perspiring. Some researchers believe that these glands may be the human equivalent of the other animals’ musky sex-scent glands – so while you might not wanna stink up a whole room, a little bit of body odor might actually get you a mate! Mammary glands, which secrete milk in lactating people, and ceruminous glands, the ones that make your cerumen or earwax, are two types of modified apocrine sweat glands. Finally, your sebaceous or oil glands are found everywhere but in the thick skin in your palms and foot soles. Their ducts are smaller on your limbs but they are pretty big on your face, neck and upper chest. Most of your sebaceous glands secrete their sebum, on oily substance, into hair follicles, where it can travel to the surface of your skin. And well, yes…they can cause wicked pimples. Their primary goal is to soften and lubricate your skin and hair and help slow water loss from the skin in dry environments (...) The irony here is that about the half of the products that I showed you at the beginning of this episode are used to wash away our natural protective, moisturizing oils, while the other half are there to add them back through lotions and conditioners. Deodorant though...I think we are all glad it exists!