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A&P 1 Unit 5: Integument

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D.J. Hennager

on 12 February 2018

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Transcript of A&P 1 Unit 5: Integument

There are three major pigments that contribute to skin color. Melanin provides the brown seen in tanning and darker skin colors, carotene can give an orange coloring (and eating a lot of carrots will turn you skin color a bit). Hemoglobin makes skin more pinkish. In fact, if someone has very pink skin and a Pulse Ox reading of 100%, this is likely due to hemoglobin being loaded with carbon monoxide in CO poisoning. The skin will also turn red with inflammation and increased blood flow due to the hemoglobin in the blood.
Chapter 5: Integument
Accessory Structures
Skin Appearnace
Basal Cell Carcinoma
Squamous Cell Carcinoma
Partial Thickness
Full Thickness
Rule of Nines
As we learned in histology, the epidermis is composed of keratinized stratified squamous epithelia. The main type of cell is the keratinocyte but there are also other cells like melanocytes, Merkel cells and Langerhans cells.
Keratinocytes produce keratin and are the major cell of the skin. Langerhans cells are macrophages, cells that engulf debris and alert the immune system to threats from pathogens. Melanocytes produce the brown pigment melanin that protects the skin from UV rays from the sun, and Merkel cells are touch receptors.
There are four layers of the epidermis. There is a fifth in thick skin like the palm of the hands and the soles of the feet.
The next layer up is the stratum spinosum. Cells contain a web of intermediate filaments to add strength. The cells contain protective melanin granules and there are Langerhans cells that provide immune protection.
In the palm and in the soles of the feet, there is a lucidum layer that is transpartent, consists of a few rows of flat dead keratinocytes.
To remember basal, think that the basement is the lowest level of a building. The basal layer is deepest, firmly attached to the dermis, contains a single rose of young keratinocytes and is undergoing rapid division.
The outermost layer of skin is called the stratum corneum. This layer composes 75% of the epidermis and it functions in waterproofing, protection from abrasion and penetration, and prevents biological, chemical and physical penetration.
Melanoma is, by far, the most concerning type of skin cancer. Melanoma is both highly metastatic but it is also resistant to chemotherapy.
There are four (or five) main characteristics that can help you differentiate a mole from a melanoma. The characteristics line up as the ABCDE rule. If what looks like a mole is asymmetric (larger on one side versus the other), if the mole as a bumpy border, if there are multiple colors (rather than a uniform color) or if the diameter is larger than a pencil eraser, the mole could be melanoma. E, sometimes stands for elevation though often moles will grow outward beyond the skin with time. E, sometimes stands for evolving as changing over time. If a mole is elevating rapidly or changing over time, it could be melanoma.
Here is a bit of a closer look at the ABCD (and E) rule.
In an interesting example of anatomical variability, the location where melanoma is likely to develop differs in males and females. You might practice mastery thinking by trying to think of reasons for these differences.
Melanoma is treated by surgical excision, immunotherapy, and radiation. The chance of survival decreases rapidly with the thickness of the lesion.
A pretty important topic when discussing the skin is skin cancer. While most skin tumors are benign and do not spread, there are three major types of skin cancer we will cover. A crucial risk factor in skin cancer is a functioning p53 gene. p53 alerts a cell that there is damage to the cell's DNA, usually caused by UV radiation, and so the cell should not divide. If p53 malfunction, a damage cell can replicate and may continue to replicate causing the unchecked growth of cancer.
A functioning p53 gene will detect damaged DNA and prevent a cell from replicating, resulting in its ultimate destruction.
The three major types of skin cancer are basal cell carcinoma, squamous cell carcinoma, and melanoma.
As mentioned earlier, the first threat to life with a burn is fluid and protein loss. When protein is lost, is cannot be used to make other proteins so it may affect the ability of the liver to make proteins necessary to prevent edema (like albumin). To predict how much fluid might be lost, there is the rule of nines.
Essentially, areas of the body are assigned values that are multiples of nines. If more than 25% of the body has second degree burns, the patient should be considered to have critical wounds. If more than 10% of the body has full thickness or third degree burns, the patient is considered critical.
A full thickness burn will damage all layers of skin and will result in gray-white, cherry red, or black damage. Often there is no initial pain or edema because blood vessels and nerves have been destroyed. Skin grafting is usually necessary to treat full thickness burns.
Squamous cells carcinoma arises from keratinocytes in the stratum spinosum. This cancer arises most often on the scalp, ears and lower lip. It grows rapidly and will metastasize if not removed though the prognosis is good if removed surgically or radiated.
Notice that squamous cell cancer does tend to penetrate more deeply into the skin and thus is more likely to spread if not treated expeditiously.
Next, we will cover burns. Burns are classified in multiple ways by either "degree" or by "thickness.
Next up for us is integument (or skin).
Skin is protective becuase it is a chemical (keeps out chemicals) physical, keeps out things, and mechanical behavior (prevents cuts). The skin regulates temperature becasue when you are hot, blood enters the skin to get rid of heat or when one is cold, blood leaves the skin to avoid loss. Also, skin has sweat glands to provide evaporative cooling. The skin also senses touch and pain to provide the nervous system with information about the external world.
The skin helps with metabolism in that it synthesizes vitamin D to assist in calcium homeostasis. The skin is where we store extra blood when it isn't necessary. The skin also excretes things like ammonia and other toxins.
Hair is made of hard keratin, as opposed to the soft keratin found in the skin. As mentioned before, hair consist aa medulla, cortex, and cuticle. Pigment from melanocytes at the base of hair is responsible for the color in hair.
Hair keeps us warm, provides an immune function by alerting us to insects, and guards against cuts that might let bacterial in. Hair is distributed across the entire body.
Just a picture that shows the various anatomy of the hair follicle.
A close up of the anatomy shows the sebaceous glands and hair bulb.
When the immune system attacks bacteria near the head, white blood cells will accumulate and die resulting in the puss of a white head. If dirt can enter the whitehead, it results in a blackhead.
There are two types of hair. Vellus hair is the find body hair on children and females. Terminal hair is the coarser hair that covers the scalp, makes the eyebrows, and makes armpit and pubic hair.
A partial thickness burn will cause damage to the epidermis and the upper dermal region and will result in blistering.
Burns are now more recently classified by how deep the burn penetrates the tissue. the older method of classification was charachterized by degrees (1st through 3rd degree). A superficial partial thickness burn will only damage the epidermis and results in redness, edema and pain.
We will next cover some accessory structures of the skin like nails, hair, and sebaceous glands.
Hair is made of a harder version of keratin. We will add a few more details momentarily.
Hair has three primary regions, the medulla in the middle, the cortex, and then the cuticle.
Alopecia is a kind of loss of hair due to the immune system attacking hair follicles. True hair loss is baldness.
Basal cell carcinoma is the least malignant but it is the most common. This cancer arises from the basal cells and is slow to grow and slow to spread. In 99% of cases, basal cell carcinoma can be cured by surgical cancer
Notice that basal cell carcinoma tends to spread superficially and is one of the reasons it is less likely to metastasize (whereas melanomas tend to grow deeper into the tissue where it can reach blood vessels and spread).
Nails are pretty simple. You may note the specific anatomy if you are interested but you will not be tested over the hyponychium or proximal nail fold.
There are two main types of glands, sweat glands and sebaceous glands
Adding to these two division, there are four different types of sweat glands. Eccrine gland are in the palms, soles of the feet and forehead. Apocrine glands tend to have more oil in the sweat, which encourages bacterial growth and is the reason sweat from these areas is more odoriferous. Ceruminous glands make wax as in the ear. Lastly, mammary glands are sweat glands the secrete milk.
Sebaceous glands are all over the body and release an oil called sebum
The next layer down is the hypodermis.
The hypodermis is below the dermis.
The hypodermis is made of adipose and areolar connective tissue. The hypodermis is not technically part of the skin, it is more of the basement layer of the skin. The hypodermis contains a layer of fat to smoothen out the skin and provide some temperature insulation.
Nails are a scale like modification of the epidermis that covers the tips of the fingers and toes.
We will point out two things when it comes to skin appearance, Langer's lines and skin color. Langers lines are due to collagen fibers running in organized bundles. Since collagen provides strength to the skin, paying attention to Langer's lines when the skin is cut in surgery can allow skin to heal more readily.
The skin is composed of two layers; the epidermis and dermis. The hypodermis is not considered part of the skin but we will cover it in this section as it makes sense to cover it now. The epidermis is the outermost layer. The dermis is the next middle region. The hypodermis is the deepest region.
We next move in to the dermis.
The dermis is below the epidermis and above the hypodermis.
The dermis is composed of strong, flexible, connective tissue and includes several different cells including fibroblasts to make cartilage, macrophages for immune function, mast cells for inflammation, and white blood cells for additional immunity. The dermis is composed of two layers, the papillary and reticular layer.
The reticular layer accounts for 80% of the reticular layer. It has collagen fibers that add strength and elastin that allows stretchiness. If you pinch your skin and release it, elastic fibers allow it to pop back into space. If you try to pinch your skin and pull a patch off, collagen fibers are what prevent it.
The papillary layer is made of areolar connective tissue. The papillary layer is called because it has peg like structures that push up into the reticular layer. In the papillary layer are Meissner corpuscles that sense touch and free nerve endings that sense pain.
Mastery Thinking
Mastery Thinking
Mastery Thinking
Mastery Thinking
Mastery Thinking
There is not a whole lot of complexity to integument
Our main mastery thoughts when it comes to skin is skin cancer and burns. The first threat to life with a burn is fluid and protein loss. The main functions of th integumentary systems are protection, body temperatrue regulastion, cutaneous sensation, metabolic functions, blood reservoirs, and excretion.
The main functions of the skin are protection, body temperature regulation, sensation, metabolic assistance, reservoir for extra blood and excretion.
The next layer up sithe granulosum layer. Here, cells begin to die and dry out so there are drastic changes in the appearance.
The next layer up is the granulosum layer. Here, cells begin to die and dry out so there are drastic changes in the appearance.
Hair is made of a harder version of keratin. We will add a few more details momentarily.
There are a few types of glands that we will cover in a moment.
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