BIO 240 1st Edition Lecture 8Outline of Last LectureE. Specialized Connective Tissue i. Cartilageii. Boneiii. BloodI. Membranes Outline of Current Lecture I. Membranes A. TypesB. Cutaneous membraneC. Regions of the skinD. Details of the epidermisE. HairF. GlandsCurrent LectureI. Membranes  The smallest organs by complexity, because they’re only made up of two tissue types. A. 4 types of membranes in the body1. Serous membranes  Secretes serous fluids to reduce friction a. Pericardium  Membrane surrounding the heartb. Pleura  Membrane surrounding the lungs. c. Peritoneum  Lines the abdominopelvic cavity2. Mucous membrane  Secretes mucus and lines structures that open to the outside. 3. Synovial membrane  Secretes synovial fluid and lines synovial joints.4. Cutaneous membrane  “Skin”B. Cutaneous Membrane 1. Forms the integumentary system (an organ system contains 2 or moreorgans)2. Epidermal derivatives are the other things embedded in skin; the epidermal derivatives plus the skin equal the integumentary systema. Examples of epidermal derivatives: hair, fingernails, exocrine glands, horns claws 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.b. The epidermis makes these derivatives and then pushes them down into the dermis. 3. Characteristics of Cutaneous Membranea. Largest organ in the body by volume, making up about 7% of your total body weight. b. Serves as a protective barrier from bacteria, viruses, UV, and water. c. Synthesizes vitamin Di. Too many UV rays are bad, but some is necessary to activate the synthesis of vitamin D.ii. Vitamin D is necessary for the absorption of calcium. d. Secretes nitrogenous waste through sweat glands. e. Has millions of sensory inputs. C. Regions of the skin (2+1)1. Epidermis – Composed of keratinized stratified squamous epithelial tissue consisting of 5 layers in some places of the body (thick skin) and4 layers of the body in most places (thin skin). 2. Dermis – Composed of connective tissue in 2 layers3. Hypodermis – Layer below the dermis that is entirely adipose tissue. Sometimes called superficial fascia.D. Details of the epidermis1. Epidermis layers from deepest to most superficiala. Stratum Basale  Typically simple cuboidal cells that are mitogenic. Reproduces cells and pushes them upwards. Maintain their cuboidal shape because can receive nutrients by diffusion from the capillaries below.b. Stratum Spinosum  Cells from the basale layer that start to shrink because of a lack of nutrients. They are huge holders of keratin.c. Stratum Granulosum  Little granular balls of keratin. Cells are often referred to a keratinocytes because they have so much keratin. Look spotted or grainy. d. Stratum Lucidum  This is the extra layer that is found in only thick skin on the palms of the hands and soles of the feet. It is a thick layer of cells that gives thick skin its rough texture. e. Stratum Corneum  Flattened keratinocytes. This region can be multiple layers thick. 2. Cells of the epidermisa. Keratinocytes make up 90% of all the cell layers of the epidermis. b. Melanocytes  Cells of the epidermis only found in the stratum basale layer. About 20% of the cells in the stratum basale are melanocytes. There is the same number ofmelanocytes in the stratum basale across all races; skin tone is dependent on the amount of melanin produced, not the number of melanocytes. These cells give us our skin pigment by producing melanin, which gives us all colors from red to brown to black. Melanin shields us from UV and is what gives us our skin tone. c. Some of the cells migrate down from the stratum basale to form the epidermal derivatives. E. Hair1. Cuticle  Is the hardest outside layer of hair that is solid keratin. 2. Cortex Hardened keratin injected with melanin. This is the section of hair that contributes to hair color. 3. Medulla  Air in the hollow center of each hair follicle. This air is easyto heat up and can warm up to help with insulation. 4. Arrector pili muscle  This is not an epidermal derivative, it is a muscle. It is a small muscle attached to the base of the hair follicle. It contracts when we are cold making the hair stand straight up and giving us goose bumps. 5. Papilla  The cells at the base of the follicle. They are mitogenic and contribute to the growth of the hair. 6. Texture of hair:a. Straight – There is a round diameter to the shaft of the hair. b. Curly – There is an oval diameter to the shaft of the hair. The more curly it is the more exaggerated the oval is. 7. Color of hair:a. Black/brown – There is mostly eumelanin deposited in the cortex. The more eumelanin, the darker. b. Red – There is mostly pheomelaninc. Blonde – There is most pheomelanin but with some eumelanin. d. Gray – There is no melanin; the melanocytes in the cortex have stopped producing melanin, so when light hits the hair the air in the medulla is reflected. F. Glands1. Sebaceous gland – Oil glands. Present everywhere except on the palms of the hands and soles of the feet. 2. Sweat glands – Present everywhere3. Ceruminous glands - In your ear; wax. Specialized form of sebaceous gland. 4. Mammary glands – Produce milk. There are two in humans and more in most other