Chapter 4: Skin and Body Membranes PDF

Essentials of Human Anatomy & Physiology Thirteenth Edition Body Membranes (1 of 2) Global Edition Functions of body...

Essentials of Human Anatomy & Physiology Thirteenth Edition Body Membranes (1 of 2) Global Edition Functions of body membranes – Cover body surfaces – Line body cavities Chapter 4 – Form protective sheets around organs Skin and Body Classified according to tissue types Membranes Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Body Membranes (2 of 2) Epithelial Membranes (1 of 5) Two major categories – Epithelial membranes Epithelial membranes are simple organs ▪ Cutaneous membranes Also called covering and lining membranes ▪ Mucous membranes These membranes contain both: ▪ Serous membranes – Epithelial tissue layer – Connective tissue membranes – Connective tissue layer ▪ Synovial membranes Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Membranes (2 of 5) Cutaneous membrane = skin – Dry membrane – Outermost protective boundary – Consists of two layers ▪ Epidermis is composed of keratinized stratified squamous epithelium ▪ Dermis is mostly dense (fibrous) connective tissue Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.1a Classes of Epithelial Membranes Epithelial Membranes (3 of 5) Mucous membranes (mucosae) – Moist membranes – Some mucosae secrete protective, lubricating mucus – Line all body cavities that open to the exterior body surface – Adapted for absorption or secretion – Consists of two layers ▪ Epithelium type depends on site ▪ Loose connective tissue (lamina propria) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.1b Classes of Epithelial Membranes Epithelial Membranes (4 of 5) Serous membranes (serosae) – Line compartments in the ventral body cavity that are closed to the exterior of the body – Occur in pairs, separated by serous fluid, with a visceral and parietal layer – Consists of two layers ▪ Simple squamous epithelium ▪ Areolar connective tissue Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.1c Classes of Epithelial Figure 4.1d Classes of Epithelial Membranes Membranes Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Epithelial Membranes (5 of 5) Connective Tissue Membranes Specific serous membranes Synovial membranes – Peritoneum – Loose areolar connective tissue only (no epithelial ▪ Cover organs in the abdominal cavity tissue) – Pleurae – Line fibrous capsules surrounding joints ▪ Surround the lungs ▪ Line bursae – Pericardia ▪ Line tendon sheaths ▪ Surround the heart – Secrete a lubricating fluid to cushion organs moving against each other during muscle activity Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.2 A Typical Synovial Joint Integumentary System Integumentary system consists of the: – Skin (cutaneous membrane) – Skin appendages ▪ Sweat glands ▪ Oil glands ▪ Hair ▪ Nails Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Functions of the Integumentary Functions of the Integumentary System (1 of 2) System (2 of 2) Insulates and cushion deeper body organs Regulates heat loss as controlled by the nervous system Protects the entire body from: – Mechanical damage (bumps and cuts) Acts as a mini-excretory system; sweat aids in the – Chemical damage (acids and bases) loss of – Urea – Thermal damage (heat or cold) – Ultraviolet (UV) radiation (sunlight) – Salts – Water – Microbes (bacteria) – Water loss Synthesizes vitamin D Secretions create a protective acid mantle Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Table 4.1 Functions of the Table 4.1 Functions of the Integumentary System (1 of 2) Integumentary System (2 of 2) Functions How accomplished Functions How accomplished Protects deeper tissues from Physical barrier contains keratin, which toughens Aids in body heat loss or heat retention Heat loss: By activating sweat glands and by cells; fat cells to cushion blows; and both pressure (controlled by the nervous system) allowing blood to flush into skin capillary beds so Mechanical damage (bumps) and pain receptors, which alert the nervous system that heat can radiate from the skin surface. to possible damage. Heat retention: By not allowing blood to flush into skin capillary beds. Chemical damage (acids and bases) Has relatively impermeable keratinized cells; contains pain receptors, which alert the nervous Aids in excretion of urea and uric acid Contained in perspiration produced by sweat system to possible damage. glands. Microbe damage Has an unbroken surface and “acid mantle” (skin Synthesizes vitamin D Modified cholesterol molecules in skin converted secretions are acidic and thus inhibit microbes, such to vitamin D in the presence of sunlight. as bacteria). Phagocytes ingest foreign substances and pathogens, preventing them from penetrating into deeper body tissues. Ultraviolet (UV) radiation (damaging effects Melanin produced by melanocytes offers protection of sunlight or tanning beds) from UV damage. Thermal (heat or cold) damage Contains heat/cold/pain receptors. Desiccation (drying out) Contains a water-resistant glycolipid and keratin. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Structure of the Skin (1 of 11) Figure 4.3 Skin Structure (1 of 2) Two kinds of tissue compose the skin – Epidermis – Dermis Subcutaneous tissue (hypodermis) – Anchors the skin to underlying organs – Not technically part of the integumentary system – Composed mostly of adipose tissue – Serves as a shock absorber and insulates deeper tissues Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Structure of the Skin (3 of 11) Structure of the Skin (2 of 11) Summary of strata (layers) of the epidermis from Epidermis—outer layer deepest to most superficial – Composed of stratified squamous epithelium – Stratum basale – Most cells are keratinocytes which produce a fibrous protein called keratin – Stratum spinosum ▪ Keratinization makes the epidermis tough – Stratum granulosum ▪ Desmosomes connect keratinocytes together – Stratum lucidum (thick, hairless skin only) – Avascular – Stratum corneum – Composed of five layers (strata) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Structure of the Skin (4 of 11) Stratum basale (stratum germinativum) – Deepest layer of epidermis – Lies next to dermis – Wavy borderline with the dermis anchors the two together – Cells undergoing mitosis – Daughter cells are pushed upward to become the more superficial layers Stratum spinosum – Cells become increasingly flatter and more keratinized Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.4 The Main Structural Features Structure of the Skin (5 of 11) of the Epidermis Stratum granulosum Stratum lucidum – Formed from dead cells of the deeper strata – Occurs only in thick, hairless skin of the palms of hands and soles of feet Stratum corneum – Outermost layer of epidermis – Shingle-like dead cells are filled with keratin (protective protein prevents water loss from skin) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Structure of the Skin (6 of 11) Structure of the Skin (7 of 11) Melanin Epidermal dendritic cells – Melanin is a pigment produced by melanocytes – Alert and activate immune cells to a threat – Melanocytes are mostly in the stratum basale (bacterial or viral invasion) of the epidermis Merkel cells – Color is yellow to brown to black – Associated with sensory nerve endings – Serve as touch receptors called Merkel discs Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Structure of the Skin (8 of 11) Dermis – Connective tissue – Underlies the epidermis – Two regions ▪ Papillary ▪ Reticular Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Structure of the Skin (9 of 11) Structure of the Skin (10 of 11) Two regions of the dermis Two regions of the dermis – Papillary layer (upper dermal region) contain – Reticular layer (deepest skin layer) projections called dermal papillae ▪ Dense irregular connective tissue ▪ Areolar connective tissue ▪ Blood vessels ▪ Indent the epidermis above ▪ Sweat and oil glands ▪ Many projections contain capillary loops, and ▪ Deep pressure receptors (lamellar corpuscles) others house pain and touch receptors ▪ On palm and sole surfaces, papillae increase friction and gripping ability ▪ Fingerprints are identifying films of sweat Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.5 Light Micrograph of the Two Layers of the Dermis 100 times Structure of the Skin (11 of 11) Other dermal features – Cutaneous sensory receptors – Phagocytes – Collagen and elastic fibers – Blood vessels – Nerve supply Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Skin Color (1 of 2) Skin Color (2 of 2) Three pigments contribute to skin color Redness (erythema)—due to embarrassment, 1. Melanin inflammation, hypertension, fever, or allergy ▪ Yellow, reddish brown, or black pigments Pallor (blanching)—due to emotional stress (such as 3. Carotene fear), anemia, low blood pressure, impaired blood flow to an area ▪ Orange-yellow pigment (also found in some vegetables) Jaundice (yellow cast)—indicates a liver disorder 4. Hemoglobin Bruises (black and blue marks)—hematomas ▪ Red coloring from blood cells in dermal capillaries ▪ Oxygen content determines the extent of red coloring Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Appendages of the Skin (1 of 10) Cutaneous glands are all exocrine glands – Sebaceous glands – Sweat glands Hair and hair follicles Nails Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.3 Skin Structure (2 of 2) Appendages of the Skin (2 of 10) Sebaceous (oil) glands – Located all over the skin except for palms and soles – Produce sebum (oil) ▪ Makes skin soft and moist ▪ Prevents hair from becoming brittle ▪ Kills bacteria – Most have ducts that empty into hair follicles; others open directly onto skin surface – Glands are activated at puberty with increased androgens Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.6a Cutaneous Glands Appendages of the Skin (3 of 10) Sweat (sudoriferous) glands – Produce sweat – Widely distributed in skin Two types of sudoriferous glands 1. Eccrine glands 2. Apocrine glands Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Appendages of the Skin (4 of 10) Figure 4.6b Cutaneous Glands Eccrine glands – More numerous, located all over the body – Open via duct to sweat pores on the skin’s surface – Produce acidic sweat ▪ Water, salts, vitamin C, traces of metabolic waste – Function in body temperature regulation Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Appendages of the Skin (5 of 10) Appendages of the Skin (6 of 10) Apocrine glands Hair – Ducts empty into hair follicles in the armpit and – Located body-wide except for palms, soles, genitals nipples, lips – Begin to function at puberty – Produced by hair follicle – Release sweat that also contains fatty acids – Root is enclosed in the follicle and proteins (milky or yellowish color) – Shaft projects from the surface of the scalp or – Play a minimal role in body temperature skin regulation – Consists of hard keratinized epithelial cells – Melanocytes provide pigment for hair color – Hair grows in the matrix of the hair bulb in stratum basale Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.7a Structure of a Hair Root and Follicle Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.7b Structure of a Hair Root and Appendages of the Skin (7 of 10) Follicle Hair anatomy – Central medulla – Cortex surrounds medulla – Cuticle on outside of cortex ▪ Most heavily keratinized region of the hair – Melanin provides color Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Figure 4.7c Structure of a Hair Root and Follicle Appendages of the Skin (8 of 10) Associated hair structures – Hair follicle ▪ Composed of an inner epithelial root sheath and an outer fibrous sheath ▪ Dermal region provides a blood supply to the hair bulb (deepest part of the follicle) ▪ Arrector pili muscle connects to the hair follicle to pull hairs upright when we are cold or frightened Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.7d Structure of a Hair Root and Follicle Appendages of the Skin (9 of 10) Nails – Heavily keratinized, scalelike modifications of the epidermis – Stratum basale extends beneath the nail bed, which is responsible for growth – Lack of pigment makes nails colorless Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Figure 4.8 Structure of a Nail Appendages of the Skin (10 of 10) Parts of a nail – Free edge – Body is the visible attached portion – Nail folds are skin folds that overlap the edges of the nail; the cuticle is the proximal edge – Root of nail is embedded in skin – Growth of the nail occurs from nail matrix of nail bed Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Homeostatic Imbalances of Skin (1 of 13) Infections and allergies – Athlete’s foot ▪ Caused by fungal infection (Tinea pedis) ▪ Itchy, red peeling skin between the toes – Boils (furuncles) and carbuncles ▪ Caused by inflammation of hair follicles ▪ Carbuncles are clusters of boils caused by bacteria – Cold sores (fever blisters) ▪ Caused by human herpesvirus 1 ▪ Blisters itch and sting Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Homeostatic Imbalances of Skin (2 of 13) Infections and allergies – Contact dermatitis ▪ Caused by exposure to chemicals that provoke allergic responses ▪ Itching, redness, and swelling of the skin – Impetigo ▪ Caused by bacterial infection ▪ Pink, fluid-filled raised lesions around mouth/nose – Psoriasis ▪ Triggered by trauma, infection, hormonal changes, or stress ▪ Red, epidermal lesions covered with dry, silvery scales that itch, burn, crack, or sometimes bleed Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Homeostatic Imbalances of Skin (3 of 13) Figure 4.9 Cutaneous Lesions Burns – Tissue damage and cell death caused by heat, electricity, U V radiation, or chemicals – Associated dangers ▪ Protein denaturation and cell death ▪ Dehydration and electrolyte imbalance ▪ Circulatory shock – Result in loss of body fluids and infection from the invasion of bacteria Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Homeostatic Imbalances of Skin (4 of 13) Extent of a burn is estimated using the rule of nines – Body is divided into 11 areas for quick estimation – Each area represents about 9 percent of total body surface area ▪ The area surrounding the genitals (the perineum) represents 1 percent of body surface area Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.10a Burns Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Homeostatic Imbalances of Skin (5 of 13) Homeostatic Imbalances of Skin (6 of 13) First-degree burn (superficial burn) Third-degree burn (full-thickness burn) – Only epidermis is damaged – Destroys epidermis and dermis; burned area is painless – Skin is red and swollen – Requires skin grafts, as regeneration is not possible Second-degree burn (superficial partial-thickness – Burned area is blanched (gray-white) or black burn) – Epidermis and superficial part of dermis are damaged Fourth-degree burn (full-thickness burn) – Skin is red, painful, and blistered – Extends into deeper tissues (bone, muscle, tendons) – Regrowth of the epithelium can occur – Appears dry and leathery – Requires surgery and grafting – May require amputation Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.10b Burns Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Homeostatic Imbalances of Skin (7 of 13) Homeostatic Imbalances of Skin (8 of 13) Criteria for deeming burns critical (if any one is met): Skin cancer – Over 30 percent of body has second-degree burns – Most common form of cancer in humans – Over 10 percent of the body has third- or fourth-degree – Most important risk factor is overexposure to burns ultraviolet (UV) radiation in sunlight and tanning beds – Third- or fourth-degree burns of the face, hands, feet, or Cancer can be classified two ways genitals 1. Benign means the neoplasm (tumor) has not spread – Burns affect the airways 2. Malignant means the neoplasm has invaded other – Circumferential (around the body or limb) burns have body areas occurred Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Homeostatic Imbalances of Skin (9 of 13) Most common types of skin cancer Concept Link – Basal cell carcinoma Recall that mitosis gone wild is the basis for cancer – Squamous cell carcinoma (Chapter 3, pp. 104–105). These cells lack normal – Malignant melanoma control of cell division and divide quickly, resulting in errors during DNA replication, mitosis, or both. Cells experiencing rapid, uncontrolled growth become cancerous and can metastasize (spread) to other parts of the body. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.11a Photographs of Skin Homeostatic Imbalances of Skin (10 of 13) Cancers Basal cell carcinoma – Least malignant and most common type of skin cancer – Arises from cells in stratum basale that are altered so that they can no longer make keratin – Lesions appear as shiny, dome-shaped nodules that develop a central ulcer Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Figure 4.11b Photographs of Skin Homeostatic Imbalances of Skin (11 of 13) Cancers Squamous cell carcinoma – Believed to be induced by UV exposure – Arises from cells of stratum spinosum – Lesions appear as scaly, reddened papules that gradually form shallow ulcers – Early removal allows a good chance of cure – Metastasizes to lymph nodes if not removed Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Homeostatic Imbalances of Skin (12 of 13) Homeostatic Imbalances of Skin (13 of 13) Malignant melanoma Malignant melanoma – Most deadly of skin cancers, but accounts for – A = Asymmetry only 5 percent of skin cancers ▪ Two sides of pigmented mole do not match – Cancer of melanocytes – B = Border irregularity – Metastasizes rapidly to lymph and blood vessels ▪ Borders of mole are not smooth – C = Color – Detection uses A B C D E rule for recognizing ▪ Different colors in pigmented area melanoma – D = Diameter ▪ Spot is larger than 6 m m in diameter illi eters – E = Evolution ▪ One or more of the ABCD characteristics is evolving Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 4.11c Photographs of Skin Developmental Aspects of Skin and Cancers Body Membranes (1 of 2) Lanugo, a downy hair, covers the body by the fifth or sixth month of fetal development but disappears by birth Vernix caseosa, an oily covering, is apparent at birth Milia, small white spots, are common at birth and disappear by the third week Acne may appear during adolescence Pimples, scales, and dermatitis are more common with aging skin Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Developmental Aspects of Skin and Body Membranes (2 of 2) In youth, skin is thick, resilient, and well hydrated With aging, skin loses elasticity and thins Skin cancer is a major threat to skin exposed to excessive sunlight Balding (alopecia) and/or graying occurs with aging; both are genetically determined; other factors that may contribute include drugs and emotional stress Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  THANK YOU Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.