MICR290_Chapter 15_AFernando .pptx

Page 1: Introduction

• Title: Microbiology with Diseases by Body System - Chapter 15

• Author: Robert W. Bauman

• Lecture Prepared By: Mindy Miller-Kittrell

• Institution: North Carolina State University

• Edition: Third Edition (2012)

Page 2: The Body’s First Line of Defense

• Definition: Structures, chemicals, and processes that prevent pathogens from entering the body.

• Structures:

  • Skin

  • Mucous membranes (respiratory, digestive, urinary, reproductive systems)

• Chemicals:

  • Natural proteases

• Processes:

  • Phagocytic cells (cells that can engulf pathogens)

Page 3: Skin

• Layers: Composed of two layers:

  • Epidermis: Outer layer

  • Dermis: Inner layer

• Defensive Chemicals:

  • Perspiration (sweat) that contains salt, inhibiting pathogen growth

  • Antimicrobial peptides

  • Lysozyme (destroys bacterial cell walls)

  • Sebum (keeps skin pliable, lowers skin pH)

Page 4: Mucous Membranes

• Location: Line all body cavities open to the environment.

• Layers: Two distinct layers:

  1. Epithelium: Thin outer covering, living cells, tightly packed to prevent pathogen entry.

  2. Deeper Connective Tissue Layer

• Functions:

  • Continual shedding of cells to carry away microorganisms

  • Mucus traps microbes and contains antimicrobial chemicals

• Relevant Structures:

  • Nasal cavity, pharynx, epiglottis, larynx, esophagus, trachea, bronchi, bronchioles

Page 5: Lacrimal Apparatus

• Function: Produces and drains tears.

• Tear Mechanism: Blinking spreads tears, washing the surface of the eye.

• Chemical Defense: Lysozyme in tears breaks downt peptidoglycan in Gram-positive bacteria, protecting against infections.

• Note: Most eye infections are from Gram-negative bacteria.

Page 6: Normal Microbiota and Innate Immunity

• Microbial Antagonism: Normal microbiota outcompete potential pathogens.

  • Compete for nutrients and create an unfavorable environment for pathogens.

  • Stimulate the body’s second line of defense and provide vitamins beneficial to the host.

Page 7: Antimicrobial Peptides

• Presence: Found in skin, mucous membranes, and neutrophils.

• Function: Act against various microbes through several mechanisms.

Page 8: The Body’s Second Line of Defense

• Operation: Activated when pathogens penetrate skin or mucous membranes.

• Components: Composed of cells and antimicrobial chemicals, many originating in the blood.

• Key Component: Plasma.

Page 9: Defense Components of Blood

• Plasma: Mostly water with electrolytes, dissolved gases, nutrients, and proteins.

  • Serum: Fluid remaining when clotting factors are removed. Contains iron-binding compounds, complement proteins, and antibodies, but not fibrinogen.

Page 10: Defense Components of Blood - Formed Elements

• Definition: Cells and cell fragments in plasma.

• Types:

  • Erythrocytes: Carry oxygen and carbon dioxide.

  • Platelets: Involved in blood clotting.

  • Leukocytes: Defend against invaders (granulocytes and agranulocytes).

Page 11: Formed Elements of Blood

• Visual Representation:

  • Red Blood Cells

  • Monocyte

  • White Blood Cells (Lymphocytes, Eosinophil, Basophil, Neutrophil)

Page 12: Hematopoiesis

• Definition: Production, multiplication, and specialization of blood cells in the bone marrow.

• Cell Types: Include erythrocytes, platelets, granulocytes (basophils, neutrophils, eosinophils), monocytes, lymphocytes.

• Functions: Involvement in clotting, inflammation, gas transport, innate immunity, and adaptive immunity.

Page 13: Defense Components of Blood: Granulocytes

• Definition: Cells with large granules that stain different colors.

• Types:

  • Basophils: Stain blue with basic dye.

  • Eosinophils: Stain red/orange with acidic dye.

  • Neutrophils: Stain lilac with mixed dyes.

• Functions: Phagocytize pathogens and kill bacteria by non-phagocytic means.

Page 14: Defense Components of Blood: Agranulocytes

• Appearance: Cytoplasm appears uniform under a microscope.

• Types:

  • Lymphocytes: Involved mostly in adaptive immunity.

  • Monocytes: Mature into macrophages in tissues, act as phagocytic cells.

Page 15: Definitions

• Chemotaxis: Movement of a neutrophil in response to a chemical stimulus.

• Diapedesis: Passage of blood cells through capillary walls into tissues (squeezing).

Page 16: Lab Analysis of Leukocytes

• Differential WBC Count: Can indicate disease.

  • Increased eosinophils: allergies or parasitic infections.

  • Bacterial infections: increased leukocytes and neutrophils.

  • Viral infections: increased lymphocytes (for virus killing).

Page 17: Phagocytosis

• Definition: Process carried out by phagocytes to engulf pathogens.

• Stages:

  1. Chemotaxis

  2. Adherence

  3. Ingestion

  4. Killing

  5. Elimination

Page 18: Phagocytosis Process

• Stages Explained:

  1. Chemotaxis toward microbes.

  2. Adherence to microbes.

  3. Ingestion by phagocytes.

  4. Fusion with lysosomes for killing microbes.

  5. Elimination through exocytosis.

Page 19: Host Defenses: Phagocytosis Mechanism

• Visual: Animation illustrating the process of phagocytosis.

Page 20: Nonphagocytic Killing: Eosinophils

• Function:

  • Attack and secrete toxins on parasitic helminths.

  • Elevated eosinophils indicate helminth infestation.

• Mechanism: Eosinophil DNA can form structures that kill some bacteria.

Page 21: Nonphagocytic Killing: Neutrophils

• Functions: Produce chemicals that kill invading pathogens.

• Mechanism: Generate extracellular traps (NETs) that bind and kill bacteria.

• Fact: Both eosinophils and neutrophils can kill bacteria via phagocytic and non-phagocytic means.

Page 22: Nonphagocytic Killing: Natural Killer Lymphocytes

• Definition: NK Cells or Natural Killer Cells.

• Function: Secrete toxins onto the surface of infected cells and tumors, differentiating between normal and abnormal cells.

Page 23: Chemical Defenses Against Pathogens: Interferons

• Function: Released by infected cells to inhibit viral spread.

• Types:

  • Type I (alpha and beta)

  • Type II (gamma)

Page 24: Interferon Mechanism

• Process: Viral infection triggers interferon release by infected cells, protecting neighboring cells through AVP activation.

Page 25: Chemical Defenses Against Pathogens: Complement

• Definition: A set of serum proteins that lead to the lysis of foreign cells.

• Activation Pathways:

  • Classical pathway

  • Alternative pathway

  • Lectin pathway

• End result: Triggers inflammation, attracts phagocytes, and kills microbes by MAC attack.

Page 26: Complement Cascade Process

• Visual Diagram: Classical pathway and complement cascade with steps of activation and effects on pathogens.

Page 27: Membrane Attack Complex

• Visual Representation: Structure and function of membrane attack complexes (MAC) against pathogens.

Page 28: Inflammation

• Definition: Nonspecific response to tissue damage, characterized by redness, heat, swelling, and pain.

• Types:

  • Acute: Quick, beneficial response.

  • Chronic: Long-lasting.

• Role in Defense: Involves dilation, permeability increase of vessels, migration of phagocytes, and tissue repair.

Page 29: Vascular Changes During Inflammation

• Visuals: Illustrate changes in blood vessel permeability and fluid movement during inflammation.

Page 30: Fever

• Definition: Body temperature over 37°C, triggered by pyrogens.

• Mechanism: Pyrogens stimulate the hypothalamus to increase core temperature; includes various pyrogens like bacterial toxins.

Page 31: Questions?

• Discussion: Open for any questions regarding the material covered.