Unit 4 Study Guide

Topics: Bone, Epidermis, Skeletal system Pages: 15 (2346 words) Published: March 12, 2013
Unit 4 Lecture Study Guide
Use the lecture folder to help you complete this guide. The more detail you can provide the better prepared for the test you will be.

1. What is the integumentary system and its primary characteristics?

- the skin and its derivates (sweat and oil glands, hairs and nails)

- provides external protection for the body

2. Describe and give at least one example of each of the functions of the integumentary system.

1. Protection- skin secretions

2. body temperature regulation- production of copious amounts of sweat to dissipate heat

3. coetaneous sensation- nerve endings- detect painful stimuli

4. Metabolic Functions- chemical conversion of many substances

5. blood reservoir- vasoconstriction and vasodilatation

6. Excretion- elimination or nitrogen- containing wastes, salt and water

3. Differentiate between chemical, physical/mechanical and biological barriers provided by the integumentary system. Be sure to provide a minimum of one example for each.

1. Chemical Barriers (skin secretion and melanin)
1. Skin secretions (acid mantle)
a. Low pH and sebum slow bacterial growth on skin surface b. Human defensin – natural antibiotic
c. Cathelicidins – proteins that prevent Strep A infection in wounded skin 2. Melanin – chemical pigment that prevents UV damage
2. Physical/Mechanical Barriers – continuity of the skin and hardness of keratinized cells 3. Continuity prevents bacterial invasion
4. Glycolipids prevent diffusion of water and water-soluble substances between cells 5. Substances that are able to penetrate the skin:
a. Lipid-soluble substances (i.e., oxygen, carbon dioxide, steroids, and fat-soluble vitamins) b. Oleoresins of certain plants (ex. Poison ivy and poison oak) c. Organic solvents (ex. Acetone, dry cleaning fluid, and paint thinner) d. Salts of heavy metals (ex. Lead, mercury, and nickel) e. Penetration enhancers

3. Biological Barriers – Langerhans’ cells, macrophages, and DNA 6. Langerhans’ cells in epidermis present antigens to lymphocytes 7. Dermal macrophages (2nd line of defense) – attack bacteria and viruses that have penetrated the epidermis 8. DNA structure – the electrons in DNA absorb UV radiation and converts it to heat

4. Create a chart that helps you differentiate the epidermis and dermis. Be sure to include things such as cell composition, cell populations and layers.

1. Epidermis

i. Composed of epithelial tissue (keratinized stratified squamous) ii. Cell population:
1. Keratinocytes (majority) – produce keratin a. Keratin – fibrous protein; waterproofing b. Keratinocytes arise from the stratum basale c. Dead cells in the upper portions of the epidermis 2. Melanocytes – synthesize melanin

a. Found in the deepest layer of the epidermis b. Melanin pigments are taken up by keratinocytes and accumulated on the superficial side of their nuclei; protects the cells’ nuclei from UV radiation. 3. Langerhans’ cells (aka epidermal dendritic cells) – macrophages a. Arise from the bone marrow

b. Most abundant in the stratum spinosum 4. Merkel cells – sensory reception
a. Located at the epidermal-dermal junction iii. Outermost portion of the skin
iv. Subdivided into four or five distinct layers
1. Stratum basale (aka, stratum germinativum) – deepest layer a. Attached to the dermis
b. Single row of rapidly dividing keratinocytes c. Melanocytes and occasionally Merkel cells are found in this layer 2. Stratum spinosum...
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