BIO 253, Week 6 Notes Chapter 5 Integumentary System
BIO 253, Week 6 Notes Chapter 5 Integumentary System Bio-253-06
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This 8 page Class Notes was uploaded by Talia Ali on Friday September 16, 2016. The Class Notes belongs to Bio-253-06 at Jackson College taught by Proefessor Brandon Cooley in Fall 2016. Since its upload, it has received 13 views. For similar materials see Human Anatomy and Physiology in Human Anatomy and Physiology I, Biology at Jackson College.
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Date Created: 09/16/16
Jackson College Fall Semester 2016 Professor: Mr. Brandon Cooley Anatomy and Physiology 1 Integumentary System ___ Notes Introduction: Epidermis The epidermis is the layer of skin that is above the dermis and hypodermis. Epi = Outside. The study of the skin is DERMATOLOGY. Skin is the body’s largest organ. DON’T FORGET. ● The cells that are in the epidermis include: ○ Keratinocytes - Proteins that protect the skin ○ Melanocytes - Give the skin pigment/color that protects the skin from UV rays ○ Intraepidermal Macrophages or Langerhans Cells - Remember that macrophages often have to do with the immune system, so these cells help the skin and body fight disease. ○ Tactile Epithelial Cells or Merkel Cells - Help you feel or sense touch. (Tactile = Touch) The skin is a big helper when it comes to protecting the body, as well as secreting oils, absorbing water, and stopping the absorption of UV rays. DON’T FORGET that CYTE means CELL. Stratums ● These layers transition from having living cells at their bottoms to dead cells at their tops: ○ Stratum Granulosum ○ Stratum Spinosum ● This layer is not available where the skin is thin: ○ Stratum Lucidum ● This layer is made of dead cells, and all keratinization is complete: ○ Stratum Corneum ● This layer is where tissue is grown and healed: ○ Stratum Basale A callus is formed when the epidermis thickens unusually. This can occur as a result of something rubbing hard against the skin, for example, violinists often have callouses on all of their fingers as a result of pressing down on the metal strings on their violins. A callus is like a scar, and often times if you press on that spot you can’t feel anything. Epidermal growth happens in the Stratum Basale as a result of mitosis. Calluses form because of the skin being worn away constantly so the rate of mitosis increases. Introduction: Dermis The dermis is the layer of skin below the epidermis but above the hypodermis. It is made out of dense irregular connective tissue, made of collagen (strength) and elastin (flexibility), and it also houses sweat glands, hair follicles, vessels, nerves and oil glands. There are two regions in the dermis layer. These would be: ● The Papillary Region - gives us the ridges and folds that makeup our fingerprints. Dermal papillae cause the folds. This region is made of areolar connective tissue. Includes: ○ Meissner Corpuscles - Sense of touch ○ Free Nerve Endings - Sensing differences in temperature, sensing pain, tickling, and itching. ● The Reticular Region - Thickest part of the dermis. ○ Epidermal Ridges = Fingerprints Introduction: Hypodermis The hypodermis is directly below the dermis and is made up of subcutaneous tissue (cutaneous means skin, maybe think of CUTting the skin) which is also made up of areolar connective tissue and adipose connective tissue. (Adipose means fat, and there is fat underneath the skin.) Introduction: Skin Color - (What Makes It Up and Why We Have It) The skin color and tone each person has is made up as a result of melanin pigments that protect skin cells. Melanin is made up of two structures, one that is black or brown, and the other that ranges from yellow to red. Melanin is used to absorb UV radiation. People get tans as a result of more sunlight exposure because more melanocytes are needed to block the extra radiation, which is why people get darker. NOTE: Every person has the same amount of melanocytes but genetically different levels of activity. Carotene (think carrot) has the ability to turn your skin orange, which is why after you eat a ton of carrots you might see your skin change colors. Hemoglobin is what give cells their bright red color, and also help the blood cell carry oxygen through the bloodstream. Albinism is the medical term for having little to no melanin or melanocytes. Introduction: Accessory Structures of the Skin The accessory structures of the skin are found in the epidermis. ● Hair ○ Made up of the cuticle, cortex, and medulla. ○ Shaft - Visible ○ Root - Not Visible ○ Follicle - Part of the epidermis that goes into the dermis and surrounds the root ○ Bulb - Located at the base of the follicle ● Matrix ○ Mitosis ● Arrector Pili Muscles ○ Causes the hair to stand up, also known as goosebumps. ● Hair Root Plexuses ○ Sends messages to the brain when movement is detected. ● Growth of Hair ○ Hair grows using mitosis in the bulb of the follicle. The growth occurs in a cycle, the end being the hair falling out. ● Color of Hair ○ Melanocytes in hair bulb move melanin into the shaft, the more melanin means the darker the hair. White hair occurs because of air bubbles in the hair’s medulla. ● Function of Hair ○ Keeps you warm. ○ Protects you from sunburn. ○ You feel the touch sensation of light. Introduction: Skin Glands ● Sebaceous Glands ○ Produce oil (sebum) at the base of hair glands, lubricates the skin, and is waterproof. ● Sudoriferous Glands ○ Produce sweat, obviously increased activity during warm weather. Sweat has proteins that are similar to the ones found in plasma. Two types of sweat glands are: ■ Eccrine - it is not found near hair, and is almost everywhere on the body. You produce 0.6 Liters of sweat from these glands a day to 4 Liters an hour maximum. ■ Apocrine - Empties into the hair follicle. These glands can be found in the nose, ear, armpits, urogenital areas. This gland is involved with infant bonding and the secretion of hormones and pheromones. ● Ceruminous Glands ○ Trap and carry out debris within the ear. These keep your eardrum lubricated and stops it from being dry. These is also flexible and water resistant. ● Lacrimal Glands ○ Clears debris from your eyes, produces tears. Introduction: Nails Nails are broad plates of keratin and stratified squamous epithelium that give protection to the fingertips. Introduction: Physiology of Skin ● Thermoregulation ○ Circulates blood above the hypodermis and removes thermal heat away from the body. ● Blood Reservoir ○ Regulates the body’s blood pressure. For example, when blood pressure gets too high, blood is moved above the hypodermis to prevent a stroke. ● Cutaneous Sensations ○ Feeling temperature change, pressure and pain. ● Excretion and Absorption ○ Excrete : Lose Absorb : Gain ● Creates Vitamin D ○ The body needs vitamin D to absorb calcium for the bones. Introduction: Maintaining Homeostasis of the Skin ● Easy to heal because it has a strong vascular (blood) supply and access to stem cells. ● Epidermal Wound Healing is when an abrasion happens only to the epidermis. ○ Contact Inhibition: Epidermal cells fill up a space and stop filling it when they come into contact with each other. ● Deep Wound Healing happens when there’s an injury below the epidermis. The stages are: ○ Inflammatory ○ Migratory ○ Proliferative ○ Maturation ● Fibrosis is when the skin scars up. It means that there is an abundance of collagen fibers. Introduction: Skin and Aging Most changes to the skin during aging happen in a person’s early 40s. Aging changes the proteins in the dermis. Collagen fibers begin to disappear, leaving saggy skin. Elastin fibers begin to break down, which causes wrinkles. Introduction: Skin Disorders There are three types of skin cancer: ● Basal Cell Carcinomas aren’t really something to be worried about as they rarely metastasize. They make up 78% of all skin cancers. ● Squamous Cell Carcinomas are moderately dangerous. They could metastasize and they could not. These cancers come from stratum spinosum. They make up 20% of all skin cancer. ● Malignant Melanomas are deadly and come from melanocytes. Introduction: Skin Burns There are five types of burns: ● Partial Thickness burns are pretty gentle, the epidermis can heal itself with no problems. ● First Degree burns only appear on the surface of the epidermis, there shouldn’t be blisters and usually a good flush with cold water should do the trick. ● Second Degree is bad, but not terrible, it destroys the epidermis and a part of the dermis. ● Third Degree completely destroys the epidermis and dermis. You may go numb on that part of the body.