It can spread practically anywhere. It may be difficult to determine whether a mole, bump or sore has developed into cancer, or which cancer. Muilenburg recommends using the ABCDE test to help evaluate whether an abnormal growth may be melanoma:. Make a difference in the fight against cancer by donating to cancer research. Call us anytime. What's the difference in skin cells? Muilenburg recommends using the ABCDE test to help evaluate whether an abnormal growth may be melanoma: A is for asymmetry: Does the mole have an irregular shape?
B is for border: Is it rough or notched around the edges? C is for color: It is changing shade or color? D is for diameter: Is it larger than the size of a pencil eraser? E is for evolution or elevation: Is the spot growing in height or width? Related Articles Cancer: When good cells go bad. The sebaceous glands found in the dermis secrete a substance called sebum that helps to lubricate and protect our skin from drying out.
Beneath the dermis is the deepest layer of our skin. It is alternatively termed hypodermis, subcutis, or subcutaneous tissue. It contains many collagen cells as well as fat. Fat, in particular, helps insulate our body from the cold and act as a cushion for our internal structures such as muscles and organs when something hits us. Fat can also be called upon by the body in times of great need as an energy source.
Given the alternative names for this layer, it should come as no surprise that this is the layer where subcutaneous injections are given into via a hypodermic needle. Skin sensory receptors: Those nearest the surface of the skin include receptors that detect gentle pressure, temperature, and vibrations, as well as naked nerve endings dendrites that detect pain.
Deeper in the dermis are naked dendrites that wind around the bases of hair follicles and detect motions of the hairs, as well as receptors such as Pacinian corpuscles that respond to strong pressure and vibrations.
Skin color is determined largely by the amount of melanin pigment produced by melanocytes in the skin. Skin color is largely determined by a pigment called melanin but other things are involved.
Your skin is made up of three main layers, and the most superficial of these is called the epidermis. The epidermis itself is made up of several different layers. Melanocyte: Cross-section of skin showing melanin in melanocytes. The deepest of the epidermal layers is called the stratum basale or stratum germinativum. In this layer lie important cells called melanocytes.
Their name is derived from two parts: melano-, which means black or darkness, and -cyte, which means cell. Melanocytes are irregularly shaped cells that produce and store a pigment called melanin. The most abundant type of melanin is called eumelanin. This pigment is stored in organelles called melanosomes. Eumelanin is responsible for the brown and black pigmentation of human skin or the lack thereof if little of it is produced.
The production of melanin is called melanogenesis—genesis means formation or development. Regardless of background, every person has largely the same number of melanocytes, but the genetics of each person is what determines how much melanin is produced and how it is distributed throughout the skin.
For example, light skinned individuals may have darker places like nipples and moles. Conversely, dark skinned individuals have a lighter tone to the palms of their hands. Another critical factor, exposure to sunlight, triggers the production of melanin as well. This is what gives us a tan. People with darker skin have more active melanocytes compared to people with lighter skin.
However, the pigment of our skin also involves the most abundant cells of our epidermis, the keratinocytes. While melanocytes produce, store, and release melanin, keratinocytes are the largest recipients of this pigment.
The transfer of melanin from melanocytes to keratinocytes occurs thanks to the long tentacles each melanocyte extends to upwards of 40 keratinocytes. Tanned Skin: Exposure to UV radiation through tanning causes changes in the pigmentation of the skin by increasing melanin production. Privacy Policy. Skip to main content. Integumentary System. They are mostly found in thick skin, on the palms of hands and soles of feet.
They are difficult to tell apart from Melanocytes. These look like 'onion' bulbs, and are commonly found in the dermis and subcutaneous tissue. The afferent nerve ending at the centre is enveloped by multiple concentric layers of flattened cells and an external capsule of connective tissue. These are pressure sensitive. Clinical significance Abnormal keratinocyte desquamation contributes to the development of acne. Sunburn : apoptosis of keratinocytes Blistering skin disorders e.
Dendritic processes transfer melanosomes to adjacent and distant keratinocytes. Langerhans cells Definition : : macrophages of the skin ; a type of dendritic cell Location : : stratum spinosum Characteristics Langerhans cells act as antigen-presenting cells APCs. Characteristics Rich in keratin filaments, desmosomes , and small, dense blue granules Merkel cells are connected to enlarged axon terminals via synapse -like junctions.
The Merkel cell-neurite complex is known as a Merkel disc receptor. Hair shaft Extends above the epidermis Connects to the hair root in the deep dermis Hair bulb Root of the hair follicle ; located deep in the dermal papilla Receives blood and nutrients from a capillary network of vessels to sustain hair growth Arrector pili muscle Description: obliquely directed smooth muscle fibers that attach to the dermal sheath surrounding hair follicles Function Contraction, which is responsible for piloerection goosebumps Conservation of body heat Innervated by the sympathetic autonomic nervous system Glands Sebaceous glands Sweat glands Eccrine sweat glands Apocrine sweat glands Description Exocrine holocrine branched glands Composed of a secretory unit called glomerulum or acrosyringium; surrounded by myoepithelial cells The combination of sebaceous gland , arrector pili muscle , and hair follicle is known as the pilosebaceous unit.
Exocrine glands with a spiral duct acrosyringium and secretory ducts that open into sweat pores Exocrine glands with a secretory unit glomerulum and excretory ducts that open into hair follicles Location and distribution Dermis Predominantly located on the face and scalp Absent on palms and soles Deep in the dermis and hypodermis Most areas of the body Absent in lips , ear canal, clitoris , labia minora , and glans penis Mostly axilla , perineum , areola of the nipple , and external ear Function Secretion of sebum An oily, waxy substance which is a lubricant and a waterproof layer for the skin and hair Has photoprotective, antimicrobial, and antioxidant properties Secretion of sweat thermoregulation Modified apocrine cells produce ear wax or breast milk.
References Fuchs E. Scratching the surface of skin development. Lookingbill and Marks' Principles of Dermatology. Saunders Elsevier ; Layers of the Skin. Updated: May 15, Accessed: May 15, Zhang S-X. An Atlas of Histology.
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