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ODU BIOL 109N - Tissue Part 2

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BIOL 109n 1st Edition Lecture 7Outline of Last Lecture I. Cell JunctionsII. MembranesIII. Connective Tissue Membranes IV. Organs and organ systems Outline of Current Lecture I. Skin: An Organ System - Integumentary System - Skin LayersII. Derivative of the skin- Hair, nails, sweat glands, oil glands, wax glandsIII. Skin color - Melanin- Types of cancer - ABCDEs of Melanoma- Health issues- Albinism- Carotene and Hemoglobin - Basal Cell Carcinoma- Squamous Cell Carcinoma- MelanomaIV. Homeostasis - Feedback Mechanisms- Hypothalamus and body temperatureCurrent Lecture- The skin is the largest organ - Functions of the skin I. Protects against bacterial invasion, UV radiation, and physical and chemical stressII. Prevents water lossIII. Regulates body temperature IV. Receives stimuli- Skin layers- has three principle layers. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.1. Epidermis (Epi. On, over) – the thin, outer layer, which forms a protective barrier against environmental hazards. It’s composed of several layers of epithelial cells. Deepest layer of rapidly dividing cells. The outer layer skin that we see it made up of dead cell. These dead cells are constantly being shed. It lacks blood vessels. Cells receive nourishment from the dermis, but die as they move toward the surface. 2. The dermis – is a much thicker layer than the epidermis. It lies just beneath the epidermis and consists primarily of connective tissue. It contains blood vessels, sweat glans, oil glands and sensory structures. It does not wear away. (tattoos) Dermis is laced with nerves and sensory receptors. Mostly connective tissue. Collagen and elastic fibers are found in the lower layer, which allows the skin to stretch and return to its original shape. 3. Hypodermis – or subcutaneous layer. Layer of loose connective tissue jus below the epidermis and dermis. Anchors skin to tissue of organs underneath, fat storage, temperature regulation, protection, not considered part of the skin.- Derivative of the skinIntegumentary system – consists of nails, sweat glands, and oil glands. It is considered to be an organ system because the skin and its derivatives function together to provide many services. - Hair- primary function is protection, grows over most of the body, components: shaf-extends above the skin surface and root- extends into the dermis or hypodermis where itis embedded in a follicle. - Nails – protects the tips of out toes and fingers. Nails are embedded in very sensitive tissue, they also function as sensory antennas. - Glands 1. Oil glands – found all over the body except the palms of the hands and soled of the feet. Oil lubricates hair and skin and contains substances that inhibit bacteria 2. Sweat glands- produce sweat that helps in the regulation of body temperature. Some metabolic wastes are excreted in sweat. 3. Wax glands- modified sweat glands found in external ear canal. Wax protects the ear by trapping small particles.- Skin color Two interacting factors produce skin color: I. The quality and distribution of pigment II. Blood flowThe pigment called melanin- protects the body by absorbing solar radiation. It produces cells called melanocytes at the base of epidermis. Melanocytes produceand secrete melanin pigment and responsible for skin color. Inside the cell melanosome produces melanin. Melanocytes absorb light, it protects and forms a layer over the nucleus to protect your DNA. Located in the bottom layer of epidermis. Keratinocyte – produces keratin protein, which makes the skin tough. - Sunburns: there are 2 types of UV (ultraviolet) radiation:I. UVA – goes deeply into the cell and changes melanin to a darker colorII. UVB- causes sunburn, does not penetrate as deeply but causes more damage causing a rapid production increase in melanin, which could form a tumor. - Types of cancer: there are 3 types of cancer:I. Basal cell carcinoma – the most common form of skin cancer, arises in the rapidly dividing cells of the deepest layer of epidermisII. Squamous cell carcinoma- the second most common form of skin cancer, arises in the newly formed skin cells as they flatten and move towards the skin surfaceIII. Melanoma- is the least common and most dangerous type of cancer. It arises in melanocytes, the pigment-producing cells of the skin. When left untreated metastasize spread rapidly throughout the body. - ABCDEs of cancer: I. A- asymmetry, irregular shapeII. B- border , unclear borderIII. C- colors such as red, white, blueIV. D- diameter, no more than 5mm. - Health Issues: I. Avoid prolonged exposure to the sun II. Wear a hatIII. Use sunscreen IV. Avoid tanning salon - Albinism: a genetic defect that makes the body unable to produce or distribute melanin. (Each person has the same amount of melanin, 5 million) The more melanin you produce the more protected you are. Albino people lack an enzyme called tyrosine, which produced melanocytes. - Carotene – yellow to orange pigment. Most obvious in palms and soles, accumulated in stratumcorneum and hypodermis, can be converted to vitamin A for vision and epidermal health. Yellowish-tinge of some Asians - Hemoglobin – pinkish hue of fair skin 1. Homeostasis- is the constant adjustment made by the organ systems to respond to changes in the internal and external environments while limiting too large variations of the internal condition required for life. Depends on the nervous and endocrine systems, which are responsible for internal communication. Maintained primarily through negative feedback mechanism- Negative feedback mechanism – corrective measures that slow or reverse a variation from the normal value of a factor, such as blood glucose level or body temperature, and return thefactor to its normal value. These are the steps: - Stimulus – produces a change to a variable (the factor being regulated) drinking a soda- Receptors- detects the change. The receptor monitors the environment and responds to change (stimuli). Blood sugar goes up- Control center (such as brain ) – information travels among the pathways to the control center. The control center determines the appropriate response and course of action. Pancreas output of insulin - Effector (such ash a muscle or gland) – information sent from the control center travels down the efferent pathway to the effector. Blood sugar goes down, a response


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