Integumentary System - PDF

The Integumentary System Image: Essentials of Human Anatomy and Physiology, 12th Edition, Marieb and Keller Slides Source: homepage.smc.edu › wissmann_paul › IntegumentarySystem Slide Source Immune System: https://www.cirm.ca.gov › files › files › about_stemcells › Unit_4_Lesson...

The Integumentary System Image: Essentials of Human Anatomy and Physiology, 12th Edition, Marieb and Keller Slides Source: homepage.smc.edu › wissmann_paul › IntegumentarySystem Slide Source Immune System: https://www.cirm.ca.gov › files › files › about_stemcells › Unit_4_Lesson Vikram Sharma, SoBS Immune System Slides: web.iitd.ac.in › ~vperumal The Integumentary System Definition? Two distinct regions  Epidermis  Dermis Functions of skin Protection Synthesizes vitamin D with UV Homeostasis Sensory reception (nerve endings) Epithelium: layers (on left) and cell types (on right) Remember… Four basic types of tissue Epithelium – epidermis just discussed Connective tissue - dermis Muscle tissue Nervous tissue Dermis Strong, flexible connective tissue: your “hide” Cells: fibroblasts, macrophages, mast cells, WBCs Fiber types: collagen, elastic, reticular Rich supply of nerves and vessels Critical role in temperature regulation (the vessels) Two layers (see next slides)  Papillary – areolar connective tissue; includes dermal papillae  Reticular – “reticulum” (network) of collagen and reticular fibers *Dermis layers *Dermal papillae * * Epidermis and dermis of (a) thick skin and (b) thin skin (which one makes the difference?) Fingerprints, palmprints, footprints Dermal papillae lie atop dermal ridges Elevate the overlying epidermis into epidermal ridges Are “sweat films” because of sweat pores Genetically determined Flexion creases The dermis is the receptive site for the pigment of tattoos Deep dermis, from continual folding Fibers Collagen: strength and resilience Elastic fibers: stretch-recoil  Striae: stretch marks Tension lines (or lines of cleavage)  The direction the bundles of fibers are directed Hypodermis “Hypodermis” (Gk) = below the skin “Subcutaneous” (Latin) = below the skin Also called “superficial fascia” “fascia” (Latin) =band; in anatomy: sheet of connective tissue Fatty tissue which stores fat and anchors skin (areolar tissue and adipose cells) Different patterns of accumulation (male/female) Skin color Three skin pigments  Melanin:the most important  Carotene: from carrots and yellow vegies  Hemoglobin: the pink of light skin Melanin in granules passes from melanocytes (same number in all races) to keratinocytes in stratum basale  Digested by lysosomes  Variations in color  Protection from UV light vs vitamin D? Skin appendages Derived from epidermis but extend into dermis Include  Hair and hair follicles  Sebaceous (oil) glands  Sweat (sudoiferous) glands  Nails Nails Of hard keratin Corresponds to hooves and claws Grows from nail matrix Hair and hair follicles: complex Derived from epidermis and dermis Everywhere but palms, soles, nipples, parts of genitalia *“arrector pili” is smooth muscle * Hair bulb: epithelial cells surrounding papilla Hair papilla is connective tissue________________  Functions of hair  Warmth – less in man than other mammals  Sense light touch of the skin  Protection - scalp Parts  Root imbedded in skin  Shaft projecting above skin surface Make up of hair – hard keratin Three concentric layers  Medulla (core)  Cortex (surrounds medulla)  Cuticle (single layers, overlapping)  Types of hair  Vellus:fine, short hairs  Intermediate hairs  Terminal: longer, courser hair Hair growth: averages 2 mm/week  Active: growing  Resting phase then shed Hair loss  Thinning – age related  Male pattern baldness Hair color  Amount of melanin for black or brown; distinct form of melanin for red  White: decreased melanin and air bubbles in the medulla  Genetically determined though influenced by hormones and environment Sebaceous (oil) glands Entire body except palms and soles Produce sebum by holocrine secretion Oils and lubricates  Sweat glands Entire skin surface except nipples and part of external genitalia Prevent overheating 500 cc to 12 l/day! (is mostly water) Humans most efficient (only mammals have) Produced in response to stress as well as heat  Types of sweat glands Eccrine or merocrine  Most numerous  True sweat: 99% water, some salts, traces of waste  Open through pores Apocrine  Axillary, anal and genital areas only  Ducts open into hair follices  The organic molecules in it decompose with time - odor Modified apocrine glands  Ceruminous– secrete earwax  Mammary – secrete milk Disorders of the integumentary system Burns  Threat to life Catastrophic loss of body fluids Dehydration and fatal circulatory shock Infection  Types First degree – epidermis: redness (e.g. sunburn) Second degree – epidermis and upper dermis: blister Third degree - full thickness Infections : Direct Contact, Vector Borne, Wounds Skin cancer Burns First-degree (epidermis only; redness) Second-degree (epidermis and dermis, with blistering) Third-degree (full thickness, destroying epidermis, dermis, often part of hypodermis)  Estimate by “rule of 9’s” Critical burns Over 10% of the body has third- degree burns 25 % of the body has second- degree burns Third-degree burns on face, hands, or feet Tumors of the skin Benign, e.g. warts Cancer – associated with UV exposure (also skin aging)  Aktinickeratosis - premalignant  Basal cell - cells of stratum basale  Squamous cell - keratinocytes  Melanoma – melanocytes: most dangerous; recognition: A - Asymmetry B - Border irregularity C - Colors D - Diameter larger than 6 mm  Skin Cancer Sqaumous cell carcinoma Basal cell carcinoma Melanoma Discussion What happens when we contract an infection or a disease Basic Organization and Function of the Immune System The immune system is the body’s response to disease and injury  Nonspecific response (innate immunity)  Specific response (acquired immunity) T-cell (part of the specific immune response) The immune system A functional system – NOT an organ system: Complex system – includes Skin – physical barrier Lining of mucus membranes – physical barrier Secretions – tears, mucus etc - antimicrobial Blood cells and vasculature – WBCs Bone marrow Liver – makes complement proteins Lymphatic system and lymphoid organs Most tissues – have resident immune cells The Immune System Overview of the Immune System Immune System Innate Adaptive (Nonspecific) (Specific) 1o line of defense 2o line of defense Interactions between the two systems  A typical immune response INNATE IMMUNITY ACQUIRED IMMUNITY Rapid responses to a Slower responses to broad range of microbes specific microbes External defenses Internal defenses Skin Phagocytic cells Humoral response Mucous membranes Antimicrobial proteins (antibodies) Secretions Inflammatory response Invading microbes Natural killer cells Cell-mediated response Complement (pathogens) (cytotoxic lymphocytes)  Innate immunity vs Adaptive Immunity Innate Immunity Adaptive Immunity (first line of defense) (second line of defense) No time lag A lag period Not antigen specific Antigen specific No memory Development of memory Anatomical Barriers - Mechanical Factors Skin Mucociliary escalator Flushing action of saliva, tears, urine Anatomical Barriers – Chemical factors Antimicrobial HCl in Lysozyme in tears Peptides in sweat stomach /saliva  Anatomical Barriers – Biological factors Normal flora – microbes in many parts of the body Normal flora – > 1000 species of bacteria Normal flora – competes with pathogens for nutrients and space Innate immune system internal defenses Innate immune system: components of Blood Complement proteins Coagulation proteins Extracellular Cytokines WBCs  White blood cells (WBCs) Macrophages B-lymphocytes T-lymphocytes Natural killer(NK) cells Mast cells Neutrophils in innate immune response Most abundant WBCs (~50-60%) Efficient phagocytes Most important cells of the innate immune system Phagocytosis Phago = to eat Cyte = cell WBCs (eg. Neutrophils) – find, eat and digest microbes ! How do neutrophils find microbes ? https://youtu.be/I_xh-bkiv_c https://www.youtube.com/watch?v=ZUUfd P87Ssg How do neutrophils eat and digest microbes ? Granule s What’s in the granules ? Lysozyme – digests bacterial cell wall; other antimicrobial proteins Additional role of neutrophils Triggers inflammatory response Monocytes Monocytes (~5% of WBCs) Migrate into the tissues and become Macrophages Lung Bone Liver Brain intestine Macrophages “Big eaters” Phagocytosis of microbes in tissue (neutrophils are present only in blood) Antigen presentation Natural killer cells Not B-lymphocytes / T- lymphocytes Important part of the innate immune system Kill virus /bacteria infected cells (Intracellular pathogens) Kills cancer cells NK cells differentiate choose cells to kill ? Uninfected cell / Normal cell Microbe infected cell / cancer cell Some cell surface proteins are miss How does the killer kill ? Kills both host cells and microbe Release of granules with perforins and proteases Toll-like receptors (TLRs) Transmembrane proteins Present on macrophages / few other cells Conserved across vertebrates Important part of innate immune system TLRs – What do they do ? They look out for microbes (or their components) They bind to the microbes (or their components) They trigger a cascade of events to kill or protect against pathogens THEY ARE INNATE IMMUNE SENSORS TLRs – look out for microbes TLRs – bind to microbes / components of microbes Summary: innate response – internal defenses – Cellular (WBCs) Come into play when the external defenses are breached Neutrophils Monocytes /macrophages NK cells TLRs Innate immune system: components of Blood Complement proteins Coagulation proteins Cytokines WBCs Cytokines Small proteins – secreted by cells of the immune system Affect the behaviour of other cells signalling molecules Key players in innate and acquired immunity Which cells release cytokines ? Cells of the immune system: Neutrophils – when they encounter a pathogen Macrophages – when they encounter a pathogen TLRs – bind to microbe / components of a microbe NK cells – on encountering a microbe infected cell /tumour cell Lymphocytes – when they are activated Examples of cytokines Interferons Interleukins Tumour necrosis factor (TNF) Interferons (IFN) Signalling proteins produced by by virus infected monocytes and lymphocytes Secreted proteins – Key anti-viral proteins “Interfere” with virus replication Warn the neighbouring cells that a virus is around... If we did not have IFNs – most of us may die of influenza virus infection How does IFN warn the neighbouring cells ? 61 The infected cells release IFN antiviral state antiviral state antiviral state antiviral state 62 Virus infects the neighbouring cells antiviral state antiviral state antiviral state antiviral state 63 Prewarned cells are able to quickly inhibit the virus antiviral state antiviral state antiviral state antiviral state 64  How do interferons inhibit viruses ? Inactive host protein Induction Virus ds-RNA Activation Host protein Active host protein Cascade of events Inhibition of host protein synthesis Virus cannot replicate Interleukins Interleukins – 1-37 Not stored inside cells Quickly synthesized and secreted in response to infection Key modulators of behaviour of immune cells Mostly secreted by T-lymphocytes & macrophages What to interleukins do ? Proliferation of immune cells Interleukin s Increase antibody production Inflammation Activation of immune cells Tumour necrosis factor (TNF) TNF Killing of Fever cancer Inflammation Complement (C`) a large number of distinct plasma proteins that react with one another (C1 thro’ C9) Complement can bind to microbes and coat the microbes Essential part of innate immune response Enhances adaptive immune resposne (taught later)  Complement proteins: role in innate immune systemC`protei ns Facilitates Direct lysis of pathogens Inflammation phagocytosis How do C` proteins facilitate phagocystosis ? Bacteria coated with Neutrophils have C` receptors C` Initiation of phagocytosis How do C` proteins lyse pathogens? Membrane attack complex formed by c` proteins Coagulation proteins Coagulation: mechanism to stop bleeding after injury to blood vessels Complex pathway involves Platelets Coagulation factors Vitamin K How does blood clot ? Coagulation: Delicate balance Coagulation proteins Anticoagulants Blood clotting Prevent blood clotting Inflammation Inhibit inflammation Apoptosis (prog. Cell Inhibit apoptosis death) Too much of clotting – Problem Maintenance of a balance Too little clotting - Problem Coagulation and innate immunity Pathogens and cytokines Anticoagulants Coagulation proteins Increased inflammation and increased apoptosis of infected cells Summary: what happens when external defenses fail ? INNATE IMMUNITY ACQUIRED IMMUNITY Rapid responses to a Slower responses to broad range of microbes specific microbes External defenses Internal defenses Skin Phagocytic cells Humoral response Mucous membranes Antimicrobial proteins (antibodies) Secretions Inflammatory response Invading microbes Natural killer cells Cell-mediated response (pathogens) (cytotoxic Complement lymphocytes) Summary: innate response – internal defenses Cellular Extracellular Neutrophils Cytokines Monocytes /macrophages Complement NK cells Coagulation TLRs What is an antibody? Produced by Plasma cell (B-lymphocytes producing Ab) Essential part of adaptive immunity Specifically bind a unique antigenic epitope (also called an antigenic determinant) Possesses antigen binding sites Members of the class of proteins called immunoglobulins Antibody: structure and function Fab – fragment antigen binding Fc- Fragment constant Antibody: Fab Fab region Variable region of the antibody Tip of the antibody Binds the antigen Specificity of antigen binding determined by VH and VL Antibody: Fc Fc region Constant region Base of the antibody Can bind cell receptors and complement proteins Antibodies exist in two forms Antibodies occur in 2 forms  Soluble Ag: secreted in blood and tissue  Membrane-bound Ag: found on surface of B-cell, also known as a B-cell receptor (BCR) Specific Response Antigen-antibody relationship (acquired immunity) Vaccinations depend on this Model of an antibody Involves lymphocytes (B, T and plasma cells) T-cells, made visible by fluorescent dye Key Points Integumentary System- Skin and its appendages Skin formed of different layers Critical for defense/homeostasis Immune System- Functional System Innate and Adaptive Immunity