Objectives To explain the function of the integumentary system. To identify the components of the epidermis. To list the strata of the epidermis.
Definitions Epi upon, on top of Hypo under Derm skin Serous membrane membranes that line the body cavities Mucous membrane membranes that open to the outside of the body Synovial membrane Membranes in our joints
The Integumentary System: An Overview
Introduction Organs are body structures composed of two or more different tissues. The skin and its accessory organs make up the integumentary system
Parts of the integumentary system Skin largest organ in our body Body membranes Hair Nails
Functions: Protective covering Helps regulate body temperature (homeostasis) Retards water loss from deeper tissues Houses sensory receptors Synthesizes biochemicals Excretes small quantities of waste
Consists of Cutaneous membrane Epidermis Outermost layer Dermis Middle layer Accessory structures- hair, sweat glands, sebaceous glands etc. Subcutaneous layer (hypodermis) innermost layer
Components Figure 5.1
Cutaneous Membrane Cutaneous membrane is another word for skin. Dry membrane Act as protective covering from. Mechanical damage (bumps) Chemical damage (acids and bases) Bacterial damage UV radiation Thermal damage Desiccation (drying out)
Cutaneous Membrane Regulate body temperature Prevent water loss House sensory receptors Send signals to your brain about what you can feel Synthesize various biochemicals Like Vitamin D
3 Layers of Cutaneous Membrane Epidermis: Structure: Top layer; stratified squamous tissue Function: protection Dermis: Structure: middle layer, largest layer. Hair, sweat glands, nails, oil glands Hypodermis: Structure: Bottom layer. Loose connective tissue and adipose tissue. Function: Insulation, houses major blood vessels.
The Epidermis
Thin Skin and Thick Skin The epidermis is composed of layers of keratinocytes- cells that produce keratin Thin skin = four layers (strata) Thick skin = five layers Figure 5.2
The Epidermis Composed of stratified squamous epithelium Lacks blood vessels Older cells are pushed to the top and harden in a process called keratinization.
Layers of the epidermis: From deep. Stratum basale/ germinativum (cells undergoing mitosis) Stratum spinosum Stratum granulosum Stratum lucidum (only occurs in thick, hairlss skin of palms and hands and soles of feet) Stratum corneum (cells filled with keratin to protect and prevent water loss from skin) to superficial
The Structure of the Epidermis Figure 5.4
Epidermis Cell Layers Germinative Basal cells (stem) are reproducing Spinosum- spiny layer Granulosum- grainy layer Stops dividing, start producing keratin Lucidum The clear layer found only in thick skin Corneum Exposed to surface and shed every 2 wks.
Skin color depends on Genetics Differing amounts of melanin and size of melanin granules Blood supply Interrupted blood supply leads to cyanosis- blue! Carotene Orange-yellow pigment found in orange vegetables Melanin Yellow-brown pigment Protects deeper cells from UV radiation Produced by melanocytes
Melanocytes Figure 5.5a, b
Epidermal cells Synthesize vitamin D3 (cholecalciferol) when exposed to UV Aids in absorption of calcium and phosphorus- needed for bone strength Respond to epidermal growth factor Growth Division Repair Secretion
Objectives The explain the components of the dermis. To understand why tattoos are permanent. To identify accessory organs of the integument and explain their function.
The Dermis
Dermal Organization Located between epidermis and subcutaneous layer Consists of connective tissue with collagen and elastic fibers within a gel-like substance Anchors accessory structures- hair follicles, sweat glands, blood vessels etc. Carry nutrients to upper layers of skin and help regulate temperature. Two components: Outer papillary layer Deep reticular layer
Layers of the Dermis Papillary layer Areolar tissue Contains blood vessels, lymphatics, sensory nerves of epidermis Reticular layer Dense irregular connetive tissue Contains network of collagen and elastic fibers to resist tension
Stretch Marks Caused by excessive stretching of the dermis Patterns of collagen and elastic fibers form lines of cleavage
Lines of Cleavage of the Skin Figure 5.7
Hypodermis (subcutaneous) Elastic areolar tissue and adipose tissue Stabilizes skins position against underlying organs and tissues Shock absorber and insulator Few capillaries and no vital organs Subcutaneous injection is useful to administer drugs
Structures Hair papilla Connective tissue containing capillaries and nerves Root Anchors hair into skin Shaft Part we see on the surface Consists of three layers Cuticle- overlapping shingle layer Cortex- underlying layer- pigments Medulla- core of hair
Structures Contd. Sebaceous Glands Also called holocrine glands Associated with hair follicles Discharge oily substance into hair follicles (waterproofs and moisturizes the hair shafts) Inhibits growth of bacteria Activated at puberty Arrector pili muscle Pulls on follicle, forcing the hair to stand up Cold or emotional states- goosebumps
Anatomy of a Single Hair Figure 5.9
Hair Follicles and Hair
Hair Follicles Figure 5.10a-c
Hair
Hairs Individual hairs develop from cells at the base of the hair follicle, an invagination of the lower epidermis that dips down into the dermis. As new cells are formed, old cells are pushed outward and become keratinized, forming the hair shaft. Project deep into the dermis and often into the hypodermis
Hair Color Melanin produced by melanocytes at the hair papilla Red hair also contains the pigment trichosiderin Determined by genetics
Function of Hair Head Protection from UV light Cushion a light blow to head Insulation Nostrils, ears, and eyes Prevent entry of particles Sensory Sensory nerve fiber at base of every hair
Appendages of the Skin
Appendages of the Skin
Exocrine Glands- Reach Outside Sebaceous glands (Oil glands) Associated with hair Secrete sebum, which lubricates and inhibits bacteria growth Acne- condition when they are clogged Sweat glands (Watery Glands) 2 kinds Hormonal- armpits, groin, nipples All over body
Sweat Glands Eccrine respond to body temperature; open via duct to pore on skin surface Apocrine responds to body temperature, stress, and sexual arousal; ducts empty into hair follicles Ceruminous glands modified sweat glands that secrete wax in the ear canal Mammary glands modified type of sweat glands that secrete milk
Sebaceous Glands and Hair Figure 5.11
Sweat Glands
Figure 5.12 Sweat Glands Figure 5.12a, b
Sweat and Its Function Composition: Mostly water Salts and vitamin C Some metabolic waste Fatty acids and proteins (apocrine only) Function: Helps dissipate excess heat Excretes waste products Acidic nature inhibits bacteria growth Odor is from associated bacteria
Regulation of body temperature Heat may be lost to surroundings from the skin. Body responds to excessive heat by dilation of dermal blood vessels and sweating. Body responds to excessive cooling by constricting dermal blood vessels, inactivation sweat glands and shivering.
Nails Keratinized cells that protects the tips of fingers and toes Stratified squamous overlying the nail bed Lunula is the most actively growing region of the nail root
Structures Nail Body Covers an area of the epidermis called the nail bed Nail Root Where nail production occurs Not visible on surface Cuticle Portion of stratum corneum
Structure Contd. Lunula Pale crescent area near the root were blood vessels are absent
Figure 5.13 The Structure of a Nail Figure 5.13
Loss of Homeostasis in Skin
Skin Homeostatic Imablance Infections Athlete s foot (tinea pedis) fungal infection Boils and carbuncles bacterial infection Cold sores caused by virus
Skin Homeostatic Imbalance
Skin Homeostatic Imabalance Burns Tissue damage and cell death caused by heat, electricity, radiation, or chemicals Associated dangers Dehydration Electrolyte imbalance Circulatory shock
Severity of Burns First-degree burns Only epidermis is damaged Skin is red and swollen Second-degree burns Epidermis and upper dermis are damaged Skin is red with blisters Third-degree burns Destroys entire skin layer Burn is gray-white or black
Severity of Burns
Critical Burns Burns are considered critical if Over 25% of the body has second-degree burns Over 10% of the body has third-degree burns There are third-degree burns on the face, hands, or feet
Healing of Wounds Inflammation blood vessels dilate and become more permeable Causes tissues to become red and swollen This is the body s normal response to injury Superficial cuts are filled in by reproducing epithelial cells Deeper cuts are closed off by clots, covered by scabs and eventually filled in by fibroblasts, making connective tissue. Blood vessels extend into the area, the injured tissues are replaced, and the scab falls off. Large wounds leave scars and helping may be accompanied by the formation of granulations.
Skin Cancer Cancer unregulated mitotic cell division producing abnormal mass Classified in two ways Benign does not spread Malignant metastasized (moves) to other parts of the body Skin cancer is the most common type of cancer!!
Basal Cell Carcinoma Least malignant Most common type Arises from stratum basale
Squamous Cell Carcinoma Metastasizes to lymph nodes if not removed Early removal allows a good chance of cure Believed to be sun-induced Arises from stratum spinosum
Malignant melanoma Most deadly of skin cancers Caner of melanocytes Metastasizes rapidly to lymph and blood vessels Detection uses ABCD rule
ABCD rule A = Asymmetry Two sides of pigmented mole do not match B = Border irregularity Borders of mole are not smooth C = Color Different colors in pigmented area D = Diameter Spot is lager than 6 mm in diameter
The Skeletal System The Skeletal System provides structural support The Integumentary System synthesizes vitamin D 3, essential for calcium and phosphorus absorption (bone maintenance and growth) Copyright 2010 Pearson Education, Inc.
The Muscular System The Muscular System s facial muscles pull against skin of face, producing expressions important in communication The Integumentary System synthesizes vitamin D 3, essential for normal calcium absorption (calcium ions play an essential role in muscle contraction) Copyright 2010 Pearson Education, Inc.
The Nervous System The Nervous System controls blood flow and sweat gland activity for thermoregulation; stimulates contraction of arrector pili muscles to elevate hairs The Intergumentary System s receptors in dermis and deep epidermis provide sensations of touch, pressure, vibration, temperature, and pain Copyright 2010 Pearson Education, Inc.
The Endocrine System Copyright 2010 Pearson Education, Inc. The Endocrine System includes the sex hormones that stimulate sebaceous and apocrine gland activity, and develop secondary sexual characteristics; suprarenal hormones alter blood flow to skin and mobilize lipids from fat cells The Integumentary System synthesizes vitamin D 3, precursor of calcitriol, a hormone produced by the kidneys
The Cardiovascular System The Cardiovascular System provides oxygen and nutrients; delivers hormones and cells of immune system; carries away carbon dioxide, waste products, and toxins; provides heat to maintain normal skin temperature The Integumentary System s mast cells produce localized changes in blood flow and capillary permeability Copyright 2010 Pearson Education, Inc.
The Lymphatic System Copyright 2010 Pearson Education, Inc. The Lymphoid System assists in defending the integument by providing additional macrophages and mobilizing lymphocytes The Integumentary System provides physical barriers that prevent pathogen entry; macrophages resist infection; mast cells trigger inflammation and initiate the immune reponse
The Respiratory System The Respiratory System provides oxygen and eliminates carbon dioxide The Integumentary System s hairs guard entrance to nasal cavity Copyright 2010 Pearson Education, Inc.
The Digestive System The Digestive System Provides nutrients for all cells and lipids for storage by adipocytes The Integumentary System synthesizes vitamin D 3, needed for absorption of calcium and phosphorus Copyright 2010 Pearson Education, Inc.
The Urinary System The Urinary System excretes waste products, maintains normal body fluid ph and ion composition The Integumentary System assists in elimination of water and solutes; keratinized epidermis limits fluid loss through skin Copyright 2010 Pearson Education, Inc.