Chapter 5 Lecture C Skin Functions Cancers Burns

The integumentary system is going to
function as a barrier but they’re also other functions as well
those are going to include protection there is thermoregulation regulation of body temperature there is cutaneous sensation so this would
be primarily by nerve receptors there is metabolic function this would be
mainly the synthesis of vitamin D and there’s also blood reservoirs and this idea of the blood reservoir is referring to the fact that
a lot of the blood is actually going to be present and stored in
the dermal blood vessels and there is excretion so there
are six different functions that you should be aware of our next slide is showing protection and the three types of protection are either chemical physical or mechanical
and also biological the chemical is going to be due to the
skin secretions and this would be predominantly sebum which is secreted from the sebaceous oil glands and the sebum is going to be responsible
or one of the factors responsible for the idea of an acid mantle the acid mantle refers to the
fact that there is a low pH of our skin that actually prevents the growth of bacteria and there’s also
melanin which is going to be protecting the fragile DNA which is found in the
nucleus so those are all chemical the physical or mechanical is primarily going to be due to the keratin which
remember is a tough fibrous protein thats present in the
keratinocytes and then the biological barrier is going to be found by such cells as
the epidermal dendritic cells as well as the macrophages and the macrophages are found in the dermis but both of these
are going to provide an immune protective function and then
there’s also the DNA itself there’s electrons in DNA that are going
to absorb ultraviolet radiation and actually by doing this the DNA converts the potentially destructive
radiation into harmless heat then the second important
function is thermoregulation body temperature regulation so what
happens when we’re in a hot environment and a very
cold environment so we’re well aware of the first example
in Florida because of the heat and when this
happens one way that our body cools itself is dilation of the dermal blood vessels and
so this is going to allow for perspiration and there is about a half liter of perspiration per day that we actually do
not notice so .5 liters is 500 milliliters and this would be the unnoticeable perspiration that we don’t see however
the noticeable perspiration that we do see the visible output would be on a very hot day and
this visible output is as you would expect called sensible perspiration or sensible water loss because we can
actually see it now on a very cold day the opposite is going to happen so in order for
our body to warm itself there’s going to be constriction of
these dermal blood vessels and the blood is actually going to be
shunted to deeper organs to help to warm us and as you know one of the other mechanisms to also that happens as we
start to shiver so our skeletal muscles are going to start to contract in
this case the third function is cutaneous
sensation and so this is going to be due to the exteroceptors and the exterocepters are the receptors that are on the integumentary system the external part of our body and we have the Meissner’s or the tactile corpuscles and these are going to be
found very superficial and they’re in the dermal papillae which
remember is the most superficial region of the dermis there’s also a deeper region or deeper exteroceptors and these are
the Pacinian corpuscles or the lamellar corpuscles and this is
going to require deep pressure in order to be
able to activate that so these are located much more
deeply than the Meissner’s corpuscles are the fourth function is the
metabolic function and this would be primarily the synthesis of vitamin D from cholesterol and in order for this
to happen in order for the cholesterol to be synthesized into vitamin D one of the requirements for this is sunlight
and there can be disorders that result from a lack of
vitamin D because then the calcium is not going to be absorbed into the body so this could actually affect the the bones as well there’s some other examples where
there are chemicals that are actually converted to
protect us chemical conversions of carcinogens and
some hormones and the fifth function is the
blood reservoir and it’s important to remember that up to five percent of the body’s blood volume is actually
stored in the dermal blood vessels so the dermis has
a great ability to to move blood to where it’s needed the
most then the sixth and final function is
excretion this would be the the elimination of nitrogen waste
from the body nitrogenous waste compounds and these
would be things like ammonia ammonia is NH3 there is also urea and there’s uric acid now they do a test in the hospital which is called the BUN and that stands for blood urea nitrogen and so if the BUN result is
too high this means that the kidney is not doing
its job by getting rid of important nitrogen but also the integumentary system we
know can also be one of the excretory systems and it can also get rid of nitrogen
containing compounds now the next section of your chapter is on
skin cancers these are homeostatic imbalances that you do need to be aware of and the first
type is the basale cell carcinoma and this one is the least
malignant and it’s also going to occur when the cells in the stratum basale are cancerous then there’s the squamous cell carcinoma
which is the second most common behind the basal cell carcinoma and then the worst is melanoma which is
quite rare but this would in this case this would
be cancer of the melanocytes now when we talk
about cancer the word cancer really just means
it’s an abnormal growth of a damaged cell if it starts to spread the term for spreading is called metastasize most of the time though these growths these tumors are actually benign and
so benign means harmless so when they identify something
that they suspect of possibly being cancer they’re going to
remove it and biopsy it to see if it is in fact cancerous one of the reasons that this could
actually occur is we have a gene called the p53 gene and this gene is a tumor suppression gene so it’s naturally going to have the
ability to suppress cancers so if there is something like
ultraviolet radiation that actually disables this very important gene then that could be a risk factor for
cancer one interesting medical discovery that they’ve made is that
there are actually certain skin lotions that can fix the damaged DNA and the interesting thing about that is these skin lotions are going to have enzymes within them and these enzymes are going to repair DNA mutations so there’s a lot of potential especially
for this type of lotion for future medical breakthroughs so this next slide is I’ve added some pictures here as well but one
of these pictures is in your textbook of the basal cell carcinoma and the
basal cell carcinoma as I mentioned previously is the least malignant and the most
common skin cancer it results for up to eighty percent of the cases and in this case the stratum basale
cells are going to going to grow they’re going to proliferate
and invade the dermis and the hypodermis but full cure for this happens usually in 99 percent of the cases as long as surgical excision is used and what you need to notice about this
cancer is the abnormalities that you see with the
border and the border is going to be one of the important characteristics to to identify whether something could be
possibly cancerous the squamous cell carcinoma is the
second most common skin cancer and in this case it arises from the keratinocytes of the stratum spinosum and so remember that this is the layer
that is just superficial to the stratum basale and what you see here again is the irregularity in color all
throughout this is a micrograph but you can see
certainly there’s different colors on the picture that you
see on the left of your slide and so it often is found in places
like the scalp, the ears and the lower lip but if it’s caught
early and removed surgically or by radiation therapy the prognosis is quite good and then the third type is the melanoma and the melanoma is cancer of the melanocyte itself and this is the most rare and it’s going to account for about two
to three percent of skin cancer but the it is quite growing is increasing by about 3 to 8 percent per year
in the United States and there’s poor survival if the size is greater than four millimeters so
again the size that we see here is going to be another important factor to
identify whether it could be a melanoma so these letters that are in your textbook are going to
be important in helping you helping to identify whether something
could be a melanoma so we’re going to use ABCDE rule and we are going to apply the E as well so you should know what these
letters stand for the first is that if it’s asymmetrical
so if the two sides of the pigmented area do not match so instead of
having a perfect circle we have one side of a circle and maybe a
squiggly line on the other that’s a possible indication then the border
if it is irregular and does exhibit indentations which we see in this one as
well color and you’ve seen the color example
in the previous slides with the squamous carcinoma the squamous cell carcinoma and then also
the diameter so if it’s larger than six millimeters the size of a
pencil eraser and remember in melanoma as you can see here
if it’s greater than four millimeters then there is a poor survival rate and then the last one would be the elevation
off of the skin so the last part of the chapter that you need
to know about is the burns and a burn is any sort of tissue
damage that does occur and this tissue damage can result from things like heat,
electricity radiation or certain chemicals and the
reason this can be so bad is that it’s going to denature or destroy proteins that are in the cell and eventually lead to cell death and
one of the the reasons this can be so bad is the immediate threat would be loss
of fluids so dehydration can happen very very quickly there can be electrolyte imbalances
so this could really damage the cardiovascular system or
possibly the nervous system it could lead to
kidney shut down renal shutdown or the person could even even go into shock if they’ve lost
enough blood volumes so there are lots of very very serious results
from burns that could happen now in order to diagnose whether there is a
how bad a burn is kind of a general rule that is used is called
the rule of nines and the rule of nines is going to
divide the body into 11 areas and its going to more or less give a general
estimate the severity at the burn so each area is
going to account for about 9 percent of the total body area so the anterior head is 4.5 so the total posterior and anterior head
would be nine percent the each limb would be a total of nine
percent the anterior trunk would be 18
percent posterior trunk 18 as well and so on the perineum is going to
be the additional one percent so it accounts for a total of one hundred-percent but one of the more important problems is again is immediate loss immediate loss of calories so a burn
patient needs to be provided with a lot of additional
calories a lot of times this is going to be applied this is
going to be supplied through gastric tubes in IV lines because depending on how bad the burn is the patient would not be able sometimes to eat all of these calories another possible threat beyond what we’ve already discussed here would
be sepsis and there’s a lot of deaths that
happen because of sepsis the word sepsis is referred to as a widespread bacterial infection so bacteria certainly one of the big
fears that happen with burnt skin so great care has to be
taken especially with a full thickness burn so there are three
different types of burns that you need to be aware of the first type is a partial thickness
burn and this applies to both first degree burns and
second-degree burns and a sunburn is usually a
first-degree burn you can see this shown on your slide here there’s a
1st degree burn on the fingertips and then a second degree burn on the
palm of the hand but in the 1st degree burn there’s
usually going to be epidermal damage only it’s localized
redness there is swelling, edema and there certainly would be pain that occurs and in this case in the first degree
burns there is actually no blisters so
blisters are going to be one of the main characteristics of second degree burns and a second-degree burn is going to damage the
epidermis and also the upper dermis as well and so the blisters
are actually going to occur due to the separation of the dermis and the dermis and then the third degree burns are going
to be referred to as full thickness burns these are involved in the entire
thickness of the skin so this is the worst and you can see a terrible looking
picture here on your slide there’s no initial edema or pain but
that’s only because the nerve endings are destroyed but as soon as the
nerve endings start to grow back then there is extreme pain that happens skin grafting is going to be necessary
at this point the first thing that they need to do
is to isolate the patient so they isolate the patient and they’re going to place them in an oxygen tent but they want to definitely you know
prevent the bacteria from growing they’re going to be doing skin grafts and because remember this means the
entire dermis is also damaged so it’s really the whole skin is damaged that’s why they it’s referred to as a full thickness burn
and in general burns are considered very very critical if any other following apply: so if 25 percent of the body has second degree burns or if 10 percent of the
body has third-degree burns or if there are
third-degree burns that are on very important areas like
the face, hands or the feet and the reason this can be so deadly so damaging is because if there’s damage to the face chances
are there could be damage to the beginning of the digestive tract the inside the mouth and so on important
mucosal membranes so this would mean that the burn is
particularly critical in these three situations and so the rest of your chapter is on
developmental aspects the skin and you not responsible for the
developmental aspects of the integumentary system you want to
definitely use the outline that’s at the end of chapter 5 to help you study and the review questions

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