Integumentary System Study Guide PDF

INTEGUMENTARY SYSTEM Topic Outline 1. Layers of the skin 2. Appendages of the skin 3. Skin receptors and blood vessels 4. Functions of the skin Learning Objectives After studying this topic, you will be able to: ...

INTEGUMENTARY SYSTEM Topic Outline 1. Layers of the skin 2. Appendages of the skin 3. Skin receptors and blood vessels 4. Functions of the skin Learning Objectives After studying this topic, you will be able to:  Name the two major layers of the skin and the tissue of which each is made  State the location and describe the functions of the stratum germinativum (basale) and stratum corneum  Describe the function of the Langerhans cells, melanocytes, and melanin  Describe the functions of hair and nails  Describe the functions of the secretions of sebaceous glands, ceruminous glands, and sweat glands.  Name the tissues that make up the subcutaneous tissue, and describe their function. Anatomy & Physiology Introduction The integumentary system includes the skin, hair, nails, and associated glands. It acts as the body's first line of defense against environmental hazards, regulates temperature, and prevents water loss. The skin, the body's largest organ, consists of multiple layers: the epidermis (outer layer), dermis (middle layer), and hypodermis (deepest layer). Its functions include protection, sensation, vitamin D synthesis, and excretion. Hair and nails provide additional protection, while glands (sweat and sebaceous) help in thermoregulation and maintaining skin health. This study guide describes the integumentary system, which consists of the skin and the subcutaneous tissue. Each part is made of specific tissues that have very specific functions. Amazing Facts of the Skin 1. The skin is the body's largest organ, covering about 20 square feet. It protects against pathogens and UV radiation. 2. The skin regenerates every 28-30 days, replacing its outer layer to repair damage and maintain protection. 3. Packed with nerve receptors, the skin detects touch, temperature, and pain, helping us interact with the environment and avoid harm. 4. The skin regulates body temperature through sweating and blood vessel adjustments, cooling us when hot and retaining heat when cold. 5. The skin acts as a waterproof barrier, preventing moisture loss and shielding against harmful substances and injuries. Discussion of Key Concepts Skin - the body’s largest organ. It is approximately 1.6 to 1.9 m2 in average-sized adults. The integumentary system consists of the skin and its accessory structures & the subcutaneous tissue. Major Layers of the Skin 1. Epidermis: thin outer layer of skin. Is made of stratified squamous epithelial tissue and is thickest on the palms and soles. Keratinocytes: a cell of the epidermis that produces the protein keratin. There are no capillaries (blood vessels) in the epidermis. a. Stratum Germinativum (basale): the innermost epidermal layer where mitosis takes place. New cells are continually being produced, pushing the older cells toward the skin's surface. 1 All information contained in this module are property of UCU and provided solely for educational purposes. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of UCU, is strictly prohibited.  b. Stratum Corneum: outermost epidermal layer, consists of mainly dead keratinized cells; all that is left is their keratin. The protein keratin is relatively waterproof and prevents the evaporation of body water. The stratum corneum is also a barrier to pathogens and chemicals. c. Langerhans cells: a mobile, phagocytic cell of the epidermis. d. Melanocyte: cell found in the lower epidermis. Produce a pigment-protein called melanin, a dark pigment that colors the skin. UV rays stimulate melanin production; melanin prevents further exposure of the stratum germinativum to UV rays by darkening the skin. 2. Dermis: the inner thicker layer of the skin. Made of an irregular type of fibrous connective tissue. Fibroblasts produce both collagen and elastin fiber. Collagen fibers are strong and elastin fibers are able to recoil after being stretched. a. Papillary layer: the uppermost layer of the dermis; contains capillaries to nourish the stratum germinativum (epidermis). Contains also the dermal-epidermal junction. 3. Subcutaneous Layer: connects the skin to the surface muscle. Made of areolar connective tissue and adipose (fat) tissue. It functions to provide some insulation from the cold, cushion bony prominences; and contains stored energy. The major blood vessels that supply the skin run through the subcutaneous layer. Anatomy & Physiology Appendages of the Skin 1. Sweat glands or sudoriferous glands: are coiled-like structures located in the dermis and the subcutaneous tissue. Has an excretory tube that extends to the surface where it is open into a pore. Important in the maintenance of body temperature. 2. Ceruminous glands: modified sebaceous gland located in the dermis of the ear canals and produces cerumen “ear wax”, preventing drying of the eardrum. 3. Sebaceous glands: are sac-like structure and their ducts open into the hair follicle or directly to the skin. Produce sebum, a lipid substance that prevents drying of the skin and hair and inhibits the growth of bacteria. 4. Hair a. Hair follicles: a sheath in which each hair grows and develops. Are made of epidermal tissue. b. Hair root: located at the base of a hair follicle where mitosis takes place. The new cells produce keratin, get their color from melanin, then die and are incorporated into the hair shaft. 5. Nail a. Nail follicles: found on the ends of fingers and toes. Mitosis takes place in the nail root, and the cells produce keratin (a stronger form of protein than found in the hair) and then die. Skin Receptors The sensory receptors in the dermis are for the cutaneous senses: touch, pressure, heat, cold, and pain. The purpose of receptors and sensations is to provide the central nervous system (CNS) with information about the external environment and its effect on the skin. This information may stimulate responses. The sensitivity of the skin depends on the number of receptors. Blood Vessels Besides capillaries in the dermis, the other blood vessels of great importance are the arterioles. Arterioles: are small arteries, and the smooth muscle in their walls permits them to constrict and dilate. This is important in the maintenance of body temperature. Vasoconstriction in cold temperatures decreases dermal blood flow to conserve heat in the body's core. Vasodilatation in warm temperatures increases dermal blood flow to bring heat to the surface to be lost. Regulation of the diameter of arterioles in response to temperature changes is controlled by the nervous system. Functions of the Skin 1. Protection of deeper tissue against drying and against invasion of pathogenic organisms and chemicals. 2. Regulation of body temperature by dissipation of heat to the surrounding air. 3. Sensory receptors provide information about the external environment. 2 All information contained in this module are property of UCU and provided solely for educational purposes. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of UCU, is strictly prohibited. Other Functions of Skin 1. Excretion: small amounts of urea (the waste product of protein metabolism) and sodium chloride are excreted in sweat. 2. Formation of vitamin D. There is a form of cholesterol in the skin that on exposure to UVR, is changed to Vitamin D. Vitamin D is important in the absorption of calcium & phosphorus from food in the intestine & promotes deposition in the bone. Lack of vitamin D is either from poor diet, lack of sunshine, or both. Activity Write your answer on a separate sheet of paper. 1. Name the functions of the skin. 2. Name the layers of the skin starting at the deepest to the most superficial layer. 3. Name the glands associated with the skin and name the product each of these glands secretes. Interactive Link https://tinyurl.com/ywkbtah9 Anatomy & Physiology Key Terms 1. Ceruminous gland - an exocrine gland in the dermis of the ear canal that secretes cerumen 2. Dermis - part of the skin next to the epidermis 3. Epidermis - the outermost layer of the skin 4. Hair follicle - the structure within the skin in which hair grows 5. Keratin - a protein produced by epidermal cells, found in the epidermis, hair, and nails 6. Melanin - a protein pigment produced by melanocytes. Absorbs ultraviolet light; gives color to the skin, hair, iris, and choroid layer of the eye 7. Receptors - peripheral beginning of a sensory neuron's dendrites 8. Sebaceous glands - are oil-producing glands 9. Sweat glands - are sweat-producing glands 10. Stratum corneum - the outermost layer of the epidermis, consisting of dead cells 11. Stratum germinativum (basale) - the innermost layer of the epidermis 12. Subcutaneous tissue - the layer of connective tissue between the dermis and the deeper tissue Summary The integumentary system is the outermost organ system of the body. The skin protects the body against pathogens and chemicals, minimizes loss or entry of water, blocks the harmful effects of sunlight, and produces vitamin D. Sensory receptors in the skin provide information about the external environment, and the skin helps regulate body temperature in response to environmental changes. The subcutaneous tissue is a secondary line of defense against pathogens, a site of fat storage, and the other metabolic functions of adipose tissue. Review Questions 1. The outermost portion of the skin is the: a) Hypodermis c) dermis b) Subcutaneous layer d) epidermis 2. All of the following are functions of the skin except: a) Protection c) temperature regulation b) vitamin B synthesis d) sensation 3. Which of the layers of the epidermis contains hardened keratinized cells? a) Stratum lucidum c) Stratum granulosum b) Stratum basale d) Stratum corneum 4. Which of the following chemicals is responsible for skin color? a) Keratin c) Vitamin D b) Melanin d) Collagen 3 All information contained in this module are property of UCU and provided solely for educational purposes. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of UCU, is strictly prohibited.  5. Vitamin D is synthesized in the skin by the action of ______ a) Melanin c) Keratin b) UV radiation d) Vitamin A 6. The primary function of hair is: a) Protection c) to increase surface area b) sensory perception d) temperature regulation 7. A structure located in the dermis that allows for hair to stand on end is known as: a) Arrector pili muscle c) Tertiary protein b) Levator papillae muscle d) Erector muscle 8. Perspiration is the substance produced by: a) ceruminous glands c) sebaceous glands b) sudoriferous glands d) oil glands 9. Which layer contains blood vessels? a) Epidermis c) stratum corneum b) stratum basale d) dermis 10. Which of the following should not happen in response to a lower-than-normal body temperature? a) Shivering c) Closing of sweat glands b) Vasoconstriction in extremities d) Opening of sweat glands Anatomy & Physiology Critical Thinking 1. A woman has stretch marks on her abdomen, but she claims she has never been pregnant. Is this possible? 2. Pulling on hair can cause significant pain, yet cutting hair is painless. Why does this occur? Readings and References  Tortora, G. J. (9th Ed.). Introduction to the Human Body: The Essentials of Anatomy and Physiology. Wiley.  Mader, S. S. (7th Ed.). Understanding Human Anatomy and Physiology. McGraw-Hill Education.  Memmler, R. L., Cohen, B. J., & Woods, M. A. (7th Ed.). Structures and Function of the Human Body. Lippincott Williams & Wilkins.  Scanlon, V. C., & Sanders, T. (5th Ed.). Essentials of Anatomy and Physiology. F.A. Davis Company.  Thibodeau, G. A., & Patton, K. T. (8th Ed.). Anatomy and Physiology. Mosby.  Regan, J., & Russo, A. (9th Ed.). Seeley’s Essentials of Anatomy and Physiology. McGraw-Hill Education.  Marieb, E. N. (11th Ed.). Essentials of Human Anatomy and Physiology. Pearson. 4 All information contained in this module are property of UCU and provided solely for educational purposes. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of UCU, is strictly prohibited.