Integumentary System - Editable PPT

 Functions of the skin: Protection from water, air, infection, chemicals, UV radiation Sensations such as pressure, heat, cold, & pain Temperature regulation- body can be heated or cooled by sweat and blood flow near surface Excretion of waste through sweat  The top layer of the...

 Functions of the skin: Protection from water, air, infection, chemicals, UV radiation Sensations such as pressure, heat, cold, & pain Temperature regulation- body can be heated or cooled by sweat and blood flow near surface Excretion of waste through sweat  The top layer of the skin Composed of stratified squamous epithelial tissue Stratum corneum- Layer of dead cells 20-30 thick. Thick, keratinized cells protect the deeper layers. Regularly shed from the body. Stratum lucidum- (clear layer)- a thin layer of translucent cells only found in thick skin of the palms and soles of feet Stratum granulosum- Cells here begin to flatten and disintegrate. Accumulate keratin granules, responsible for water- proofing the skin. Stratum spinosum- “Spiny layer”. Named for the irregular shape of the cells. Several cells thick. Contains pre-keratin filaments. Stratum basale- Constantly dividing and pushing up cells into the next layer.  Melanocytes are spider-shaped epithelial cells found in the bottom 2 layers of the epidermis (stratum basale & stratum spinosum) Melanocytesproduce a pigment called melanin, which is absorbed by the nearby epidermal cells. Darker-skinned people have the same number of melanocytes as light-skinned people. The difference is in the amount of melanin produced.  Melanin protects the skin against harmful UV rays. When UV radiation mutates a skin cell’s DNA, the cells begin to divide uncontrollably. This is called skin cancer. Types of skin cancer: Melanoma- uncontrolled division of melanocytes Basal cell carcinoma- uncontrolled division of cells in the stratum basale layer Squamous cell carcinoma- uncontrolled division of cells in the stratum spinosum layer The skin has several functions, but primarily protects the body. The epidermis is the top layer of the skin and it grows from the stratum basale towards the surface. Melanocytes produce melanin, protecting the body from UV radiation which can cause mutations that result in cancer.  The dermis is composed of dense irregular connective tissue It contains nerves, blood vessels, sweat glands, and hair follicles  The boundary between the epidermis and the dermis is a wavy layer called the dermal papillae. This irregular surface is the cause of your fingerprints (or epidermal ridges).  These ridges increase friction allowing us to pick up objects more easily.  The dermis is composed of 2 layers: The papillary layer made of loose connective tissue The reticular layer made of bundles of collagen fibers The arrangement of the collagen fibers cause lines of cleavage or lines of tension.  Lines of cleavage are important to surgeons. Cuts should be made parallel to the lines of cleavage for quicker healing and less scar tissue formation.  During exercise, the blood vessels in the dermis swell causing skin to appear red. This allows heat from the blood to dissipate, cooling the body. When blood supply to the skin is restricted for a prolonged time, decubitus ulcers (bedsores) can form.  Hypodermis is also known as the subcutaneous layer  Not actually a part of the skin  Composed of loose, fatty connective tissue that connects the skin to muscle or bone  The dermis is found just deep of the epidermis and contains blood vessels and nerves. It has a papillary layer and a reticular layer made of collagen that forms lines of cleavage. The hypodermis or subcutaneous layer attaches the dermis to the underlying organs.  There are 2 types of glands found in the skin: Sudoriferous (sweat) glands Sebaceous (oil) glands  More than 2.5 million per person There are 2 types: Eccrine:Merocrine sweat glands that are abundant and often found on the palms, soles of feet, and forehead Apocrine: found almost exclusively in the armpit and genital areas  Eccrine sweat glands are long tubes that open into pores on the surface of the skin. Sweat is 99% water with trace amounts of salts, vitamins, wastes, and an antimicrobial peptide called dermcidin. Sweat is generally acidic.  Apocrine sweat glands contain all the traditional components of sweat PLUS fatty substances and proteins. Originally odorless, but bacteria begin to break down fat & proteins causing body odor. Increase during puberty & may be similar to scent glands of animals.  Produce sebum (oil) Sebaceou Because sebum is usually s gland secreted onto hair, there are more oil glands on the scalp and face and none on palms or soles of feet Sebaceous glands are holocrine glands (whole burst cells) Function: lubricates skin and hair, kills bacteria The amount of oil produced is based on inheritance, but usually increases during puberty. The sudoriferous glands are long tubes that release sweat. If they also produce fats and proteins, they are apocrine glands. Sebaceous glands are found near hairs and produce sebum (oil).  Hair& nails are made of hard keratin We have millions of hairs on most parts of our body Functions: Head hair keeps in heat and protects us from the sun Body hair alerts us to insects Eyelashes protect the eyes Nose hair prevents the entry of foreign objects  Hair The part of the hair shaft that sticks out of the skin is called the shaft. It is protected by the Hair follicle outermost layer called a cuticle.  The Hair hair follicle (root) is shaft located in the dermis Hair cells divide within the follicle in a region called the hair bulb. The cells are filled with Hair keratin and pigments. follicle These dead cells are continually pushed out as new cells are formed. Tiny arrector pili muscles attach to the hair shaft to make hair “stand on end”. The texture of the hair (curly, straight, wavy) is based on the shape of the hair follicle opening. Hair color is determined by the amount of melanin present at the base of the hair follicle.  Nailsare protective and useful as tools. Ex: picking things up, scratching Nails have 4 basic parts: Free edge free edge visible Body nail body Root not visible Nail bed  The nail matrix nail nail produces heavily body matrix keratinized cells, which become the nail body. The nail is Lateral nail folds protected on three sides by nail folds. Lunula- “little moon”; whiter lunula due to thickness of nail Proximal nail fold  Eponychium= cuticle Provides a protective seal for the nail matrix. eponychium (cuticle) root of nail nail body nail matrix free edge Hair and nails provide protection due to their high keratin content. Hair grows from the hair bulb, while nails grow from the nail matrix.