So we continue or way through the study of our body. Next we come to the Integumentary system!
So when you hear someone talking about the integumentary system they are talking about your skin. Our skin is made up of three major regions:
-Epidermis: This is the outermost superficial region.
-Dermis: This is the middle region.
-Hypodermis: This is the deepest region. It is also referred to as the superficial fascia.
The Epidermis is made of keratinized stratified squamos epithelium. It consists of four distinct cell types and around four or five layers.
The cell types in the Epidermis include:
-Keratinocytes: These produce the fibrous protein keratin
-Melanocytes: These produce brown piment melanin
-Langerhans' cells: These are epidermal macrophages that help activate the immune system.
-Merkel Cells: These function as tough receptors in association with sensory nerve endings.
The outer protion of the skin is exposed to the external environment. It functions in protection.
The epidermis is split into different layers!
The first layer is the Stratum Basale or the Basal Layer. This is the deepest layer and is firmly attached to the dermis. The basal layer consists of a single row of the youngest keratinocytes. These cells undergo rapid division. (FUN FACT: It's alternate name is Stratum Germinativum!)
The next layer of the Epidermis is the Stratum Spinosum. It is also called the Prickly layer. The cells contain a weblike system of intermediate filaments attached to demosomes. Melanin granules and Langerhans' cells are very abundant in this layer.
Next comes the Stratum Granulosum, also known as the granular layer. This layer has around three to five cell layers, where drastic changes in keratinocyte appearance occurs. It is a thin layer where keratohyaline and lamellated granules accumulate.
The next layer is know as the Stratum Lucidum, or also called the clear layer. This layer is a thin, transparent band superficial to the stratum granulosum. It has a few rows of flat, dead keratinocytes. (FUN FACT: This layer is only present in thick skin!)
The top, or outermost layer of keratinized cells, layer of the epidermis is the Stratum Corneum, or the Horny layer. This layer accounts for three quarters of the epidermal thickness. This layer has three different functions; Waterproofing, protection from abrasion and penetration, and rendering the body relatively insensitive to biological, chemical, and physical assaults.
The next layer of skin is the Dermis.
This is the second major skin region. it contains strong, flexible connective tissue. The cell types in the dermis can include fibroblasts, macrophages, and occasionally mast cells and white blood cells.
The Dermis is split into two layers!
The Papillary layer is areolar connective tissue with collagen and elastic fibers. This layer's superior surface has peglike projections that are called dermal papillae. The dermal papillae are made of capillary loops, Meissner's corpuscles, and free nerve endings.
The next layer in the dermis is the Reticular layer. This layer makes up around 80% of the thickness of the skin. The collagen fibers found in this layer add strength and resiliency to the skin, The elastin fibers stretch-recoil properties.
The next major layer of the skin is the Hypodermis. This is the subcutaneous layer deep to the skin. It is made of adipose and areolar connective tissue.
Everyone has different skin colors. We have three pigments that contribute to what color skin we have.
-Melanin: This is a yellow to reddish-brown to black pigment. It is responsible for dark skin colors. Freckles and pigmented moles result from local accumulations of melanin.
-Carotene: This is a yellow to orange pigment. It is most obvious in the palms and soles of the feet.
-Hemoglobin: This is a reddish pigment responsible for the pinkish hue in the skin.
Now everybody sweats but did you know we have different types of sweat glands that prevent the body from overheating.
-Eccrine Sweat Glands are found in the palms, soles of the feet, and the forehead.
-Apocrine Sweat Glands are found in axillary and anogenital areas.
-Ceruminous Glands are modified apocrine glands in the external ear canal that secrete cerumen.
-Mammary Glands are specialized sweat glands that secrete milk.
Our body also has another kind of gland: Sebaceous Glands. These are simple alveolar glands that are found all over the body. They secrete an oily secretion called sebum. They also soften the skin when its stimulated by hormones. (FUN FACT: You can blame these little guys for acne!)
FUN FACT: Have you ever wondered about your nails!? Well nails are a scalelike modification of the epidermis on the distal, dorsal surface of the fingers and toes!
Most girls love to have great hair! Some guys too! But do you really know everything there is to know about hair?!
Your hair is filamentous strands of dead keratinized cells that are produced by hair follicles. It has hard keratin! (FUN FACT: Hard keratin is tougher and more durable than soft keratin of the skin!) Your hair is made up of the shaft projecting from the skin and the root embedded in the skin. It also has a core called the medulla, a cortex, and an outermost cuticle. Your hair is pigmented by melanocytes at the base of the hair. (in other words that how you get your hair color!) You hair also has different functions!
-It helps to maintain warmth
-It alerts your body when insects are on your skin
-It guards the scalp against physical trauma, heat loss, and sunlight.
You can find hair anywhere on your body except for palms, soles, lips, nipples, and portions of the external genitalia.
Your hair grows from hair follicles on your scalp. A hair follicle is a root sheath extending from the epidermal surface into the dermis. The deep end is expanded forming a hair bulb. Wrapped around each hair bulb is a knot of sensory nerve endings, also known as a root hair plexus. If you bend a hair it can stimulate these endings. Our hairs act as sensitive touch receptors.
Our Integumentary System has different functions as a whole. Our skin is there for protection. It is a chemical, physical, and mechanical barrier. It also regulates our body temperatures. It can do this by Dilation, cooling, and constriction, warming, of the dermal vessels. Our exoreceptors can also sense touch and pain, which is known as the cutaneous sensation. Our skin also has metabolic functions and synthesis of vitamin D in dermal blood vessels. Our skin blood vessels store up to 5% of the body's blood volume. Our skin also goes through excretion where limited amount of nitrogenous wastes are eliminated from the body through sweating.
Our skin can get three major types of skin cancer; Basal cell carcinoma, squamos cell carcinoma, and melanoma. Melanoma, or the cancer of melanocytes is the most dangerous type of skin cancer. This is because Melanoma is highly metastic and is resistant to chemotherapy. You can tell if someone has melanoma by using the ABCD rule.
-A: Asymmetry; The two sides of the pigmented area do not match
-B: Border; It is irregular and exhibits indentations.
-C: Color; The pigmented area is black, brown, tan, and can sometimes be even red or blue.
-D: Diameter; The diameter is larger than 6mm, or the size of a pencil eraser.
This cancer is treated by wide surgical excision accompanied by immunotherapy. The chance of surviving is very poor if the lesion is over 4 mm thick.
Now its time to talk about burns.
In first-degree burns only the epidermis is damaged. The symptoms include localized redness, swelling, and pain.
In second-degree burns the epidermis and upper regions the dermis are damaged. The symptoms mimic first degree burns but blisters also appear.
In third-degree burns the entire thickness of the skin is damaged. The burned are appears gray-white, cherry red, or black. Your nerve endings are destroyed so there is no initial edema or pain.
The Rule of nines estimates the severity of burns. Your burns are considered critical if:
-Over 25% of the body has second-degree burns
-Over 10% of the body has third-degree burns.
-There are third-degree burns on face, hands, or feet.
Now I know what you're thinking...OH MY GOSH THAT WAS LONG! I bet you never thought there was that much involved in your skin. Well trust me there's even more information to know that I don't even know! Well I hope you now know more about our skin then you did before.
Be looking for my next very very very long post about our Skeletal System!!
