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The Integumentary System: How it Works and What Can Go Wrong
Transcript of The Integumentary System: How it Works and What Can Go Wrong
*Regulate Body Temperatures- Dermal vessels dilate (to cool) and constrict (to warm). Sweat glands also secrete more to cool the body.
*Sensation- receptors sense pain and touch.
*Blood Reservoir- blood vessels in the skin can store up to 5% of the body's blood.
*Metabolism- vessels in Dermis synthesis Vitamin D.
*Excretion- Certain wastes can be expelled from the body through sweat. The Integumentary System: How it Works and What Can Go Wrong By: Steven Malouff
Anatomy and Physiology Take a moment and look at the people around you. If you were told to describe their physical features, what would you say? Maybe you would talk about their hair length, or the color of that hair. Maybe you would talk about their complexion, or the tone of their skin. Maybe you would be observant enough to notice abnormalities on the skin, or perhaps the person's finger nail length. All of these are features of the Integumentary System. While it is often, though unintentionally, overlooked, the Integumentary System is an important part of the Human Body. This system, like the others, has certain responsibilities for maintaining the body. Consequently, it also has major problems when these responsibilities are not withheld. Introduction: The Epidermis The Epidermis is the outermost layer of the skin (the closest to the outside world). The Epidermis, from the surface going deeper, contains the following layers: Horny, Clear, Granular, Prickly, and Basal. Horny Layer The outermost layer of the skin. The Horny Layer (scientifically known as Stratum Corneum) is comprised of dead keratin cells. This layer accounts for 75% of the thickness of the Epidermal, and is constantly being replaced by new dead cells (which causes protection and waterproofing). Clear Layer The next deepest layer is the Clear Layer (Stratum Lucidum). This is a very thin, transparent layer that is only a few keratinocytes thick. It is only common in thicker skin (such as the hands or feet, as they encounter the most abrasion). Granular Layer This layer, also referred to as Stratum Granulosum, is very thin. The Granular Layer is the layer in which the skin cells begin to die. The skin cells will continue rising until they reach the Horny Layer. The Granular Layer is also the location of accumulated lipid (fat) and keratin granules. Prickly Layer The second deepest layer of the Epidermis is the Prickly Layer, or Stratum Spinosum. This layer is a system of filaments, and contains "bundles" of what will become keratin. In this layer, melanin and Langerhans' cells are abundant. Basal Layer The Basal Layer, Stratum Basale, is the deepest layer of the Epidermis. It is attached to the Dermis (the second Epidermal Layer). Its primary function is the rapid division of cells, which is then used to supply the entire Epidermis layer. The Epidermis contains four types of cells:
*Keratinocytes- produce keratin protein (makes hair, fingernails).
*Melanocytes- produces brown melanin pigment, which controls skin color.
*Langerhans' Cells- help activate the immune system.
*Merkel Cells- Function as touch receptors/nerve endings. The Epidermis: A Visual Representation The Dermis The Epidermis is the next major layer of the skin. It primarily consists of flexible connective tissue. The Dermis contains two layers: the papillary layer and the reticular layer. The Dermis contains the following cells:
*Fibroblasts- help provide the structure for connective tissue.
*Macrophages- cells with the goal of digesting foreign substances (immune system).
*White Blood Cells- cells that help fight disease (immune system). Papillary Layer The Papillary Layer is the more superficial (closest to surface) of the two Dermal Layers. It is comprised of collagen and elastic fibers woven into a connective tissue, as well as what projections called dermal papillae. (They contain nerves and capillary loops, which make you blush). Reticular Layer This layer is comprised of collagen fibers that add strength and make the skin resilient. It also has elastic fibers that allow the skin to stretch. The Reticular Layer makes up 80% of the skin's thickness. A Picture of the Skin The Hypodermis Of the layers of the skin, the Hypodermis is the deepest. It is only comprised of a single layer, and contains adipose and connective tissue. The main function of the Hypodermis is to insulate and maintain body temperatures. See the previous slide for a picture of the Hypodermis. Functions of the Integumentary System Skin Pigment There are three primary pigments that determine skin color:
*Melanin- yellow to red-brown to black. Pigment responsible for dark skin colors, as well as freckles/moles (which are just accumulations of pigment).
*Carotene- yellow to orange. Mainly found on palms and feet.
*Hemoglobin- red pigment responsible for "pinkish" skin hue (absent in albino people). Sweat Glands There are many types of sweat glands that secrete different substances:
*Eccrin- produce sweat to cool the body. Is found in palms, feet, and forehead.
*Apocrine- produce sweat to cool the body. Found in limbs and axillary body parts.
*Ceruminous- produce cerumen (earwax). Found in the ear canal.
*Mammary- produce milk. Found in the breasts of women. Sebaceous Glands There are other types of glands in the body known as Sebaceous Glands. These are found all over the body. They are stimulated by hormones, and secrete an oily substance called sebum. These are the glands that are responsible for acne in teenagers. Nails The nail is a modification of the epidermis. It is found only on the surface of fingers and toes. Rapid reproduction of cells in the nail fold lead to the outward growing of the nail. Refer to the diagram below: Hair Hair, to put it simply, is strands of dead keratinized cells that are produced by hair follicles. These cells contain hard keratin, which is more durable than the keratin in the skin. At the base of the hair are melanocytes, which determine hair color. Functions of hair include maintaining warmth, guarding the body from sunlight, and alerting the body to the presence of foreign objects on the skin (such as insects). Diagram of a Hair Follicle Below is a diagram of what a hair shaft looks like. The "Arrector Pili" you see is a small muscle that causes hair to stand straight up, which helps in maintaining warmth. Cancer The three main types of skin cancer are: basal cell carcinoma, squamous cell carcinoma, melanoma.
The former two are the least malignant, and easily cured. Melanoma, however, is the most dangerous type, and should thus receive the most attention. Melanoma This cancer type involves the mutation of melanocyte cells, especially in Caucasian individuals (as they have less melanin to protect them from harmful UV rays). It is very resistant to chemotherapy, and is highly metastatic (meaning it can spread. Melanoma often leads to other cancers because of its quick spreading. It can be treated if it is noticed early on, and accompanied by surgery. How Can You Tell? The "ABCDE Rule" can be used to identify Melanoma, as it displays the following characteristics:
A: Asymetry (if cut in half, the sides would not be identical).
B: Border (border is irregular and not smooth).
C: Color (affected area is black, brown, or occassionally red or blue).
D: Diameter (larger than 6mm).
E: Evolving (the affected area will change shape/location over time). Burns Burns are another major concern as they can lead to dehydration, infection, and permanent damage. Types of Burns The severity of a burn is classified into one of three types:
*First Degree- swelling and redness, but only the epidermis is damaged.
*Second Degree- swelling, redness, and blisters, with epidermis and upper regions of dermis are damaged.
*Third Degree- No initial pain (as there are no nerves left), with all skin layers damaged. How do you know how Severe a Burn is? A system called the Rule of Nines is used to determine burn severity. In this system, each limb is given a percentage. Viewed as critical if over 25% has second degree burns, 10% has third degree burns, or hands/feet/face have third degree burns. Rule of Nines diagram is on the following slide. Rule of Nines In Closing... What are the layers of the human skin? What components comprise the Integumentary System? What conditions can the skin undergo, and why is it important to understand them? These are the answers that you should know as you finish this presentation. After all, it is important to understand the Integumentary System, how it works, and what can go wrong! Here is a picture of the skin. Take notice of the Dermal Papillae, the Reticular Layer, and the location of the Dermis compared to the other skin layers.