Presentation on theme: "Chapter 6 Skin and the Integumentary System You will be able to: ACOS 5 Identify anatomical structures and functions of the integumentary system Identify."— Presentation transcript:
Chapter 6 Skin and the Integumentary System You will be able to: ACOS 5 Identify anatomical structures and functions of the integumentary system Identify accessory organs Recognize diseases and disorders of the integumentary system (examples: decubitus ulcer, melanoma, psoriasis)
Integumentary system: skin and its accessory organ Includes two distinct layers 1.epidermis—outer layer composed of stratified squamous epithelium 2.dermis—inner layer thicker than the epidermis contains dense connective tissue consisting of collagenous and elastic fibers, epithelial tissue, smooth muscle tissue, nervous tissue, and blood
A basement membrane anchors the epidermis to the dermis and separates these two skin layers. Beneath the dermis are masses of loose connective tissue and adipose tissues that bind the skin to the underlying organs called the subcutaneous layer (or hypodermis). –This is beneath the skin and not a true layer of skin. –It also serves as a shock absorber or insulator.
Epidermis Composed of five zones or strata –stratum basale *deepest cell layer *close to the dermis and is nourished by dermal blood vessels *constantly undergoing cell division –stratum spinosum –stratum granulosum
Keratinization The older cells being pushed toward the surface harden in a process called keratinization. The cytoplasm fills with strands of tough, fibrous, waterproof keratin protein. As a result, many layers of tough, tightly packed cells accumulate in the outermost areas, stratum lucidum and stratum corneum.
–stratum lucidum *found only on hands and soles of feet –stratum corneum *outermost layer *20 to 30 cell layers thick *dead cells that form this layer eventually are shed
Melanin pigment that ranges in color from yellow to brown to black produced by special cells called melanocytes found mostly in the stratum basale Freckles and moles are concentrated spots of melanin. How do we tan? What happens when we receive excessive exposure to the sun?
Skin Color Differences in skin color result from differences in the amount of melanin that melanocytes produce and in the distribution and size of the pigment granules. Skin color is mostly genetically determined—if genes instruct melanocytes to produce abundant melanin, then the skin is dark.
William Bryant Stafford—with jaundice (sun tanning)
Dermis strong, stretchy envelope that helps hold the body together (your “hide”) dense, fibrous connective tissue of the dermis consists of two major regions 1. papillary layer—upper region 2. reticular layer—deepest skin layer
1. Papillary Layer dermal papillae—fingerlike projections from the superior surface of the papillary layer that cause it to be uneven; contain capillary loops, pain receptors or touch receptors Meissner’s corpuscles—touch receptors Papillary patterns are genetically determined. Fingerprints are unique, identifying films of sweat caused by the ridges of the fingertips.
2. Reticular Layer contains blood vessels, sweat and oil glands, and deep pressure receptors called Pacinian corpuscles contains many phagocytes that act to prevent bacteria that have gotten through the epidermis from penetrating any deeper into the body contains collagen and elastic fibers abundantly supplied with blood vessels that play a role in maintaining body temperature What are decubitus ulcers? Blue Box page 116
Subcutaneous Layer (Hypodermis) consists of loose connective tissue and adipose tissue no sharp boundary between the dermis and subcutaneous layer provides insulation, helping to conserve body heat and impeding the entrance of heat from the outside
Accessory Organs of the Skin—Nails scalelike modification of the epidermis has a free edge, a body (visible attached portion), and a root (embedded in the skin) nail folds—skin folds that overlap the borders of the nails cuticle—thick proximal nail fold nail bed—stratum basale that extends beneath the nail nail matrix—thickened proximal area responsible for nail growth lunula—region over the thickened nail matrix that appears as a white crescent
Accessory Organs of the Skin—Hair millions scattered all over the body serves only a few functions—guarding the head from bumps, shielding the eyes, and helping to keep foreign objects out of the respiratory tract produced by a hair follicle parts of a hair: 1. medulla—central core 2. cortex—bulky layer that surrounds the core 3. cuticle—outermost layer that encloses the cortex; formed by a single layer of cells that overlap one another
Hair Follicle root—part of the hair enclosed in the follicle shaft—part of the hair projecting from the surface of the scalp or skin hair bulb matrix—growth zone at the end of the follicle where hair is formed by the division of stratum basale epithelial cells arrector pili—small bands of smooth muscle cells that connect each side of the hair follicle to the dermal tissue
Sebaceous (Oil) Glands found all over the skin expect palms of the hands and soles of the feet ducts usually empty into a hair follicle but some open directly to skin surface sebum—mixture of oily substances and fragmented cells that acts as a lubricant to keep skin soft and moist and prevent hair from becoming too brittle sebum contains chemicals that kill bacteria so it acts as a protectant
Sudoriferous (Sweat) Glands widely distributed in the skin—more than 2.5 million per person two types: A. eccrine glands—far more numerous and found all over the body; produce sweat when hot B. apocrine sweat glands—largely confined to the axillary and genital areas of the body; activated at puberty
Regulation of Body Temperature—page 120 Write and answer the following questions. What is the normal temperature of deep body parts? What body part plays a key role in regulating body temperature? How does the body react when the body temperature rises? How does the body react when the body temperature drops? Where does 80% of the body’s heat escape?
Healing of Wounds—pages 120-121 inflammation: when a wound becomes red and swollen due to fluids entering the damaged tissues scab: blood clot and dried tissue fluids that cover and protect underlying, damaged tissue scar: connective tissue that forms on the surface of the skin of extensive wounds granulations: small, rounded masses consisting of a new branch of a blood vessel and a cluster of collagen-secreting fibroblasts