Integumentary System Unit Intro
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School
El Camino Real High School**We aren't endorsed by this school
Course
SCIENCE HONORS
Subject
Biology
Date
Dec 17, 2024
Pages
9
Uploaded by AmbassadorPrairieDog2211
Integumentary System Unit IntroEpidermisP much ur skin Skin is largest organFunctions of skin include:★Protection (from water, air, infection, UV radiations, etc), ★Sensations (such as pressure, heat, cold, and pain), ★Temperature regulation (body can be heated/cooled by sweat and blood flow near surface)★Excretion of waste through sweat ★Productionof Vitamin D (go touch grass) Layers of the skin:1. Epidermis- Superficial region2. Dermis - Middle region3. Hypodermis- Deepest region-Subcutaneous layer deep to skin (not technically part of skin) -Mostly adipose tissue Epidermis: ● Keratinized stratified squamous epithelium
● Cells of epidermis○ Keratinocytes - produce fibrous protein keratin ○ Melanocytes■ 10-25% of cells in lower epidermis■ Produce pigment melanin● (Langerhans) cells = macrophages that help activate immune system ● Tactile (merkel) Cells - touch receptors What are the layers of epidermis?●The top layer of the skin● Composed of stratified squamous epithelial tissue
★Stratum lucidum is only on palms and soles of ur feet (NOT EVERYWHERE) Dermis:
How do melanocytes protect the body?★Melanocytes are spider-shaped epithelial cells found in the bottom 2 layers of the epidermis (stratum basale and stratum spinosum).★Melanocytes produce a pigment called melanin, which is absorbed by the nearby epidermal cells.★Darker skinned people have the same number of melanocytes as light-skinner people. The difference is inthe amount of melanin produced from those cells. ★Melanin protects the skin against harmful UV rays.★WhenUV radiation mutates a skin cell’s DNA, the cells begin to divide uncontrollably. ★This is calledskin 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 layerDermis What are the characteristics of the dermis? ★Composed of dense irregular connective tissue ★Containsnerves, blood vessels, sweat glands andhair follicles.★The boundary that separate theepidermis anddermis is a wavy layer called thedermal papillae ★This irregular surface is the cause of your fingerprints(epidermal ridges) ★These ridges increase friction allowing us to pick up objects more easily.
Dermis● Strong, flexible connective tissues● Cells include fibroblasts, macrophages, and occasionally mast cells and white blood cells.● Two layers: ○ Papillary○ ReticularThe dermis is composed of 2 layers: ● The papillary layeris made of loose connective tissue ● Thereticular layeris made of bundles of collagen fibers
● The arrangement of the collagen fibers causes lines of cleavage or lines of tension.Layers of the Dermis: Papillary layer:● Areolar connective tissue with collagen and elastic fibers and blood vessels ● Dermal papillae (folds) contain○Capillary loops○ Touch receptors○ Free nerve endings (detect pain) Layers of the Dermis: Reticular layer:● Reticular layer○ Around 80% of the thickness of dermis○ Dense irregular connective tissue○ Collagen fibers provide strength and resilience○ Elastic fibers provide stretch-recoil propertiesWhy are the lines of cleavage important?● Lines of cleavage are important to surgeons ●Cuts should be made parallelto the lines of cleavage for quicker healing and less scar tissue formation Skin color:
Three pigments contribute to skin color:1. Melanin■ Yellow to reddish brown to black, responsible for dark skin colors ■ Produced in melanocytes; migrates to keratinocytes where it forms “pigment shields”for nuclei ■ Freckles and pigmented moles 2. Carotene ● Yellow to orange, most obvious in the palms and soles 3. Hemoglobin ● Responsible for the pinkish hue in skin ● Because of blood How can blood flow in the dermis change?●During exercise, the blood vessels in the dermis swellcausing skin to appear red.● This allows heatfrom the blood to dissipate, coolingthe body.● When blood supply to the skin is restricted for a prolonged time, decubitus ulcers(bedsores) can form
What are the characteristics of hypodermis?Hypodermis - also known as the subcutaneouslayer ● Not actually a part of the skin ● Composed of loose, fatty connective tissue that connects the skin muscle or bone ● Also insulatesand stores nutrients.