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Download Integumentary System - Gantner Avenue Elementary School
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Integumentary System CHAPTER 4 Body membranes Cover surface Line body cavities Form protective sheets around organs 2 major categories: 1. epithelial membranes 2. connective tissue membranes Epithelial Membranes Cutaneous membrane(skin) Mucous membranes Serous membranes Even though we call them epithelial- they are not only composed of epithelial tissue They are epithelial tissue and connective tissue Cutaneous Membrane Skin Superficial epidermis is composed of a keratinizing stratified squamous epithelium Underlying dermis is dense fibrous connective tissue Exposed to the air and is a dry membrane Mucous membrane Composed of epithelium rest on a loose connective tissue membrane called lamina pretrial Lines all body cavities that are open to the exterior Ex: lines the hollow organs of the respiratory system, digestive system, urinary system, and reproductive tracts Most contained stratified squamous epithelium or simple columnar epithelium. Wet or moist membranes that are bathed in secretions Adapted for absorption or secretion. Serous membranes Serosa membrane Composed of a layer of simple squamous epithelium resting on a thin layer or areolar connective tissue. Line body cavities that are closed to the exterior. Occur in pairs Parietal layer lines a specific portion of the wall of the ventral body cavity Parietal layer folds on itself and forms the visceral layer Visceral layer- cover the outside of the organs in the cavity Serous membranes Serous layers are separated by a thin, clear fluid called serous fluid Serous fluid is secreted by membranes Serous fluid allows organs to slide easily across the cavity walls of one another without friction as they carry out routine functions. Serosa lining abdominal cavity- peritoneum Serosa around the lungs- pleura Serosa around the heart- pericardium Connective tissue membranes Composed of soft areolar connective tissue Contain no epithelial cells at all Line fibrous capsules of surrounding joints Provide a smooth surface between joints Secrete lubricating fluid Line small sacs of connective tissue called bursae and tubelike tendon sheaths Basic Skin Functions Keeps water and precious molecules in. Keeps water and bacteria out. The capillary network and sweat glands offer regulation of heat loss. Insulates and cushions the deeper organs. Protects the entire body from mechanical damage and UV radiation. Houses our cutaneous sensory receptors. (part of the nervous system) Structure of the skin The skin is composed of two kinds of tissue Stratified Squamous Epithelium makes up the EPIDERMIS. (This epithelium is capable of keratinizing.) 2. Dense Connective Tissue makes up the DERMIS. These two layers are firmly connected . 1. A layer of Adipose Tissue lies beneath the skin and is called the subcutaneous tissue, or HYPODERMIS. It connects the skin to underlying organs EPIDERMIS The epidermis is composed of 5 layers which are avascular called strata. The cells of the epidermis are keratinocytes – they produce the fibrous protein keratin. The deepest layer of the epidermis is the STRATUM BASALE, which is the only layer that receives nourishment by diffusion from the dermis. The Stratum Basale undergoes constant division, pushing new cells upward to become part of the next layer. Layers of the epidermis 5. STRATUM BASALE 4. STRATUM SPINOSUM 3. STRATUM GRANULOSUM 2. STRATUM LUCIDUM 1. STRATUM CORNEUM The cells become flatter and increasingly full of keratin as they move away from the dermis. The accumulation of water repellent keratin, and increasing distance form the blood and nutrient supply ultimately kills the cells. dermis The dermis is a strong stretchy envelope that helps hold your body together. It varies in thickness in different locations of the body. Layers of the dermis 1. Papillary Layer 2. Reticular Layer The papillary layer lies just below the epidermis. It is uneven and has fingerlike projections from its superior surface called DERMAL PAPILLAE. The Dermal Papillae contains small blood vessels called capillary loops, pain receptors, and touch receptors. The reticular layer is the deepest layer of the skin. It contains blood vessels, sweat and oil glands, and pressure receptors. Collagen and Elastic fibers are found throughout the dermis and are responsible for its toughness. Skin color Amount and kind (yellow, reddish brown, or black) of melanin in the epidermis Amount of carotene deposited in the stratum corneum and subcutaneous tissue Carotene is orange-yellow pigment found in carrots and other yellow-orange vegetables Amount of oxygen bound to hemoglobin in the dermal blood vessels. Skin appendages 1. Cutaneous Glands (Sebaceous Glands and Sweat Glands) 2. Hair and Hair Follicles 3. Nails Skin appendages 1 Cutaneous Glands The cutaneous glands are all exocrine glands that secrete their secretions to the skins surface via ducts. They fall into 2 groups: A. SEBACEOUS GLANDS B. SWEAT GLANDS Sebaceous glands A. Sebaceous Glands (oil glands) – their ducts usually empty into a hair follicle, but some open directly onto the skin. These glands produce SEBUM. ( a mixture of an oily substance and fragmented cells) Sebum keeps the skin soft and moist and prevents the hair from becoming brittle. It contains chemicals that kill bacteria. Sweat glands B. Sweat glands – are found all over the body, there are two main types. 1. Eccrine Glands produce SWEAT which reaches the skins surface via a duct called a PORE. Eccrine glands are an important and highly efficient factor in heat regulation. They are supplied with nerve endings which sense internal and external temps. 2. Apocrine Glands Usually confined to the axillary and genital areas. Skin appendages 2. Hair and Hair Follicles Today hairs only serve a few minor functions (eyelashes, nose hairs) A HAIR is flexible epithelial structure produced by a HAIR FOLLICLE The part of the hair enclosed in the follicle is called the ROOT. Each hair consists of a central core called the MEDULLA surrounded by a bulky CORTEX which is surrounded by the CUTICLE. SKIN Appendages 3. Nails Nails are a scale like modification of the epidermis that is similar to a hoof or claw of other animals. Nails have a free edge, a body, and a root which imbedded in the skin They are transparent and nearly colorless but appear pink because of the blood supply in the dermis below. Homeostatic Imbalance Overexposure to the sun The appearance of aging skin Bed Sores Blushing- Turning Blue Acne Allergies and Infections Burns Cancer Homeostatic imbalances of skin Infections and allergies Burns Skin cancer Athletes Foot Itchy, red, peeling condition of the skin Appears between the toes Results from a fungus infection Tinea pedis Boils and Carbuncles Inflammation of hair follicles and sebaceous glands Common in dorsal neck Carbuncles- composite boils typically caused by a bacteria infection Cold Sores Fever blisters Small, fluid-filled blisters that itch and sting Caused by a herpes simplex infection Virus localizes in a cutaneous nerve where it remains dormant until activated by emotions upset, fever, or UV radiation Usually occur around the lips and oral mucosa of the mouth Contact Dermatitis Itching, redness, swelling of the skin Progressing to blistering Caused by exposure of the skin to chemicals that provoke allergic responses in sensitive individuals Impetigo Pink, water-filled, raised lesions (commonly around the mouth and nose) Develop a yellow crust and eventually rupture Caused by a highly contageous staphlycoccus infection Common in elementary school-ages children Psorasis Chronic condition Characterized by reddened epidermal lesions covered with dry, silvery scales May be disfiguring when severe Cause is unknown: may be hereditary in some cases Attacks often triggered by trauma, infection, hormonal changes, and stress Burns Skin is only as thick as a paper towel When skin is severely damages, nearly every body system suffers Metabolism accelerates or may be impaired Changes in the immune system occur Cardiovascular system may falter Burn- tissue damage and cell death caused by intense heat, electricity, UV radiation (sunburn), certain chemicals (such acids) Burns When skin is burned and its cells destroyed, two life- threatening problems result. 1. body loses its prescious supply of fluids containing proteins and electrolytes as these seem from the burned surfaces 2. dehydration and electrolyte imbalance follow- this can lead to a shutdown of kidneys and circulatory shock Rule of the nines Divides the body into 11 areas, each counts for 9 percent of the total body surface area Additional 1% is accounted for by the area surrounding the genitals Volume of fluid lost can be estimated indirectly by determining how much of the body surface is burned by using this rule. Developmental aspects of skin and body membranes During the fifth and sixth month of fetal development the infant is covered with a downy type of hair called lanugo. Lanugo has usually been shed by birth. When a baby is born the skin is covered with vernix caseosa White, cheesy-looking substance Produced by sebacous glands Protects the baby’s skin while it is floating in water-filled sac inside the mother Newborn skin is very thin and you can see blood vessels through it Developmental aspects of skin and body membranes Milia- white spots that appear on the baby’s nose and forehead Accumulations in the sebaceous glands Usually disappear by 3 weeks after birth During adolescence skin and hair become more oily Sebaceous glands are activated Acne may appear Acne usually subsides in early adulthood and skin reaches optimal appearance when we are in our 20s and 30s. Visual changes appear in skin as we are exposed to sun, wind, abrasion, chemicals, and other irritants Developmental aspects of skin and body membranes When skin pores become clogged with pollutants and bacteria pimples, scales, and various kinds of dermatitis(skin inflammation) become visible. During old age: Amount of subcutaneous tissue decreases which leads to intolerance to cold Skin becomes dry Thinning skin make it more susceptible to bruising and other types of injuries Sunlight causes loss of elasticity Developmental aspects of skin and body membranes Hair loses its luster as we age By age 50 the number of hair follicles has dropped by 1/3 A bald man is not really hairless – he does have hairs in the bald area The hair follicles have begun to degerate Hairs are colorless and very tiny These hairs are called vellus
