Human Anatomy and Physiology PDF

Human Anatomy and Physiology Topic 5 The Integumentary System Anatomy & Physiology for Health Professions: An...

Human Anatomy and Physiology Topic 5 The Integumentary System Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Learning Objectives Identify the main anatomical portions of the integumentary system. Discuss the functions of the integumentary system. List and describe the layers of the skin. Explain how the body regulates temperature through the integumentary system. Describe common disorders of the integumentary system. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  System Overview The integumentary system is the system made up of the skin and its accessory components including hair, nails, and associated glands. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Functions of the Integumentary System The integumentary system performs several vital functions: – Protects from pathogens – Protects against abrasion by producing keratin that serves as a water repellant – Balances fluid levels by excreting of organic wastes, salts, and water via the integumentary glands – Stores lipids in the adipocytes of the dermis – Produces vitamin D - this steroid is converted to calcitriol, a hormone vital for normal calcium metabolism Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Functions of the Integumentary System The integumentary system performs several vital functions (cont.): – Provides sensory input - detects stimuli (pain, pressure, temperature, and touch) and relays this information to the nervous system – Protects underlying tissue from ultraviolet (UV) radiation by producing melanin – Helps to regulate body temperature via insulation or evaporative cooling (see next slides) Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Role of the Integumentary System in Regulating the Body Temperature When temperature increases: – Vasodilation of the blood vessels in the skin exposes heated blood to external cooling air. – Sweat glands excrete water onto the skin’s surface, allowing cooling through evaporation. When temperature decreases: – Vasoconstriction keeps cooling of blood to a minimum. – Shivering causes muscle activity that produces heat. – Hairs on the skin stand erect when arrector pili muscles contract; hence creating a dead space insulating the body from cooler surroundings. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Figure 8-7 Integumentary regulation of body temperature. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  The Skin The skin is the largest organ, weighing approximately 20 pounds (~9Kg) in an adult. A cross section of skin reveals three layers: – Epidermis – also called superficial epithelium – Dermis – Subcutaneous fascia/layer – also called hypodermis Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved. Memorize the underlined only The three layers of the skin. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Colbert Ankney Lee Copyright ©2011 by Pearson Education, Inc. All rights reserved.  Epidermis Outermost layer of the skin. Made up of 4 to 5 layers of squamous epithelial cells - keratinized stratified squamous epithelium. Deepest layer of epidermis is the stratum basale. The epidermis is not vascularized (except for the stratum basale) - nutrients must diffuse through dermal blood vessels and tissue fluid to reach the epidermis. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Epidermis Cells on the surface are constantly shedding, being replaced with new cells that grow and arise from the stratum basale every 2-4 weeks. – Cells in this layer divide and grow – Move toward the skin surface and away from the dermis below – As they move upward, they receive fewer nutrients and eventually die – Older cells are called keratinocytes, which harden with age through keratinization (keratin protein fills the cytoplasm of these cells, which collectively form the stratum corneum layer) – Dead skin cells in this layer are eventually shed from the body Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Skin Color Melanin is a brown, yellow-brown, or black pigment produced by spider-shaped specialized cells called melanocytes. Melanocytes are located deep in the epidermis and are responsible for skin color. Regardless of race, all human beings have about the same number of melanocytes. Variation in skin color is the result of the amount of melanin produced and how it is distributed, not the number of melanocytes. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Skin Color Also contributing to skin color are the pigments carotene and hemoglobin: – Carotene is yellow to orange, present in the stratum corneum and the hypodermic fatty tissue. – The color of carotene is easily seen in the palms and soles, especially in lighter-skinned individuals, where the stratum corneum is thicker. – Carotene, along with variations in melanin, contributes to the skin color of people from certain Asian countries. – Hemoglobin is the red pigment inside red blood cells. – As it circulates throughout the dermal capillaries, it gives off a pink color that is easily seen in people with fairer skin. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Dermis Component of the skin - thicker layer below the epidermis. Contains the following: – Capillaries – Collagenous/elastic fibers – Involuntary muscles – Nerve endings – Lymph vessels – Hair follicles – Sweat glands – Sebaceous/oil glands Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Dermis Nerve fibers allow us to sense what is happening in the environment. Vasodilation of capillaries in this layer causes blushing. Collagen and elastic fibers allow for the elasticity of skin, preventing tearing of skin with movement, and allowing it to return to normal shape during periods of rest. – Older people lose some of this elasticity, leading to wrinkles. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Subcutaneous Fascia/Layer - Hypodermis The innermost layer of the skin – sometimes NOT considered as part of the skin. Also known as superficial fascia. Located below the dermis - binds the skin to the organs underneath, mainly muscles. Allows the skin to slide. Mainly composed of adipose (fatty) tissue, and elastic and fibrous connective tissue. Lipocytes (fat cells) produce the fat needed to: – Provide padding to protect the deeper tissues of the body. – Act as insulation for temperature regulation. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Accessory Structures of the Integumentary System Accessory structures of the integumentary system include: – Sweat glands – Sebaceous glands – Nails – Hair and hair follicles Most accessory structures are located in the dermis and protrude through the epidermis to reach the surface of the skin. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved. Accessory Structures - Sweat Glands Also called sudoriferous glands. Sweat glands consist of a small tube originating as a coil in the deep dermis. Coiled portion is lined with sweat-secreting cells. Sweat is carried out of the skin by tubes called pores that open at the skin surface. It is made up of 99% water as well as salts, including sodium chloride. Sweat has a normal acidic pH of between 4 and 6. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved. Memorize the underlined only Figure 8-2 Sweat and sebaceous glands. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved. Accessory Structures - Sweat Glands Sweat contains dermicidin, which is a peptide that kills microbes. Sweating prevents overheating: it begins on the forehead, spreading inferiorly to the rest of the body. When sweating is caused by nervousness or fright (cold sweating), it starts on the palms, axillae, and soles before spreading throughout the body. Sweat has no odor, but bacteria degrade substances in the sweat into chemicals that give off strong smells commonly known as body odors. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved. Accessory Structures - Sweat Glands The skin contains two types of sweat glands: Merocrine (eccrine) glands: – Predominant type of sweat glands – 2-5 million in adults – Located all over the skin, are found in greater numbers on the palms, soles, neck, back, forehead, and upper lip – Are important in the regulation of temperature Apocrine sweat glands: – Become active around puberty – number ~2,000 – Mostly found in the groin, anal region, and armpits – produce smell as they come into contact with skin bacteria – Are believed to act as sexual attractants Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Accessory Structures - Sebaceous Glands and Follicles Sebaceous glands are also called oil glands. Primary located near hair follicles. Are largest on the face, neck, and upper chest. Secrete sebum, an oily mixture of fatty material and debris from cells. Sebum is secreted through small hair follicle ducts. Functions of the sebum: – Keeps hair and skin pliable and waterproof. – Inhibits bacterial growth, protecting the keratin of the hair shafts. – Lubricates the hair and skin, keeping the hair supple and slowing the loss of water from the skin. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Accessory Structures - Sebaceous Glands and Follicles Sebaceous follicles are large sebaceous glands. Their ducts discharge sebum directly onto the epidermis. They are found on the face, chest, nipples, back, and external genitalia. When sebaceous glands become overactive, usually on the scalp, an inflammation may develop around them. This is known as seborrheic dermatitis, which is a common cause of dandruff. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved. Memorize the underlined only Figure 8-2 Sweat and sebaceous glands. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Accessory Structures - Nails Nails protect the ends of the fingers and toes. Consist of a nail plate above a skin surface called nail bed. A nail is a modification of the epidermis that contains hard keratin. Part of the nail plate (nail body) that grows most actively is covered by a whitish, half-moon–shaped lunula or lunule, where epithelial cells divide and become keratinized. Nails normally appear pink in color because of underlying capillaries, with the white crescent-shaped lunula above the nail matrix. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Accessory Structures - Nails Fingernail anatomy. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved. Accessory Structures – Hairs and Hair Follicles There are ~ 2.5 million hairs on the human body, of which over 75% is on the body surface - not the head. Hairs (pili) project above the skin surface over most of the body, except for the sides and soles of the feet, palms of the hands, sides of the fingers and toes, lips, and parts of the external genitalia. They consist of a large amount of dead keratinized cells, dominated by hard keratin. Hairs are structures produced in organs called hair follicles. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Accessory Structures – Hairs and Hair Follicles Memorize the underlined only The human hair can be divided into three sections: – Bulb: a thickening of the hair at the end of the hair follicle. – Root: extends from the bulb to the skin’s surface. – Shaft: the section of the hair extending out from the skin’s surface. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved. Accessory Structures – Hairs and Hair Follicles Hair grows at an average rate of 2.5 mm per week, but this varies with sex, age, and body regions. Approximately, 90 scalp hairs are lost per day. Hair color is reflected by genetics and variations in the pigment produced by melanocytes at the hair papilla: – Darker hair has more eumelanin (which is brownish-black). – Lighter hair has more pheomelanin (which is reddish-yellow). – The different forms of melanin give hair a wide variety of shades, ranging from dark brown to yellow-brown to red. – White hair results from a lack of pigment along with the presence of air bubbles in the medulla of the hair shaft. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved. Accessory Structures – Hairs and Hair Follicles Hair color and texture. Hair colors are shown with the corresponding type of melanin; textures, with the corresponding shape of hair-shaft cross section. All three layers of the hair shaft are shown. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Burns to the Skin Caused by heat, chemicals, electricity, or radiation. Two factors affect assessments of damage: – Depth: relates to the layer(s) of skin affected by the burn – Total surface of skin damaged Portion of dermis Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee Do not memorize table All6-1. rights reserved.  First Degree Burn It is a burn that involves only the epidermis. Most common type of burn. Symptoms include redness, pain, and swelling (edema). Pain subsides in 2-3 days. Usually does not leave scars. Most sunburns are first-degree burns. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Second Degree Burn Also called partial-thickness burn. Involves the entire depth of the epidermis and a portion of the dermis. May appear red, tan, or white with blisters. Symptoms: redness, pain, and blistering. Very painful, are slow healing, and may leave scars. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Second Degree Burn Extent of blistering depends on the depth of the burn. Blisters heal within 10-14 days if there are no complications - deeper second-degree burns taking 1-3½ months. Scarring in second degree burns is common. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Third Degree Burn Also termed full-thickness burns. Affects all three layers of the skin - epidermis and dermis are completely destroyed, and deeper tissue is damaged. Skin can repair itself only from the edges of the wound. These burns often require skin grafts - if left to heal on their own may result in abnormal connective tissue fibrosis and severe disfigurement. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Third Degree Burn Surface of the burn has a leathery feel and will range in color from black, brown, tan, red, or white. Patient feels no pain because pain receptors are destroyed. Sweat and sebaceous glands, hair follicles, and blood vessels are also destroyed. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.  Figure 8-3 (continued) Assessing the degree of the burn. Anatomy & Physiology for Health Professions: An Interactive Journey, Second Edition Copyright ©2011 by Pearson Education, Inc. Colbert Ankney Lee All rights reserved.