Chapter 15

• First line of defense: Structures,chemicals,and processes that protect the body from pathogens
• Epidermis: outer layer of the skin that is made up of dead cells
• Dendritic cells: Defense cells and eat pathogens
• Collagen fibers help skin resist abrasions
• Sweat glands produce perspiration which includes Salt, antimicrobial peptides, and lysozymes
• Sebum: Reduces skins pH to 5 and helps it stay soft and oily
• Epithelium: ▪ Tightly packed, thin layer, prevents pathogen entry

  ▪ Continual shedding of cells removes microorganisms

  ▪ Dendritic cells phagocytize pathogens

  ▪ Goblet and ciliated columnar cells help remove

  invaders
• Goblet cells: Secrete mucous
• Ciliated columnar cells: Help move the mucous
• Mucous: Mucins(glycoproteins)
• Lacrimal Apparatus: Produces and drains tears from the eye
• Microbiome: Competes with potential pathogens
• Tears contain lysozyme (enzyme that breaks down bacterial cell walls)
• Plasma: Mostly water with electrolyses, dissolved gases, nutrients and proteins.
• Serum: liquid portion of blood that remains after the clotting process is complete
• Hematopoiesis: Process by which the division of stem cells in the bone marrow produce three types of “formed elements”
• Erythrocytes: Red blood cells, contain haemoglobin, transport oxygen around the body
• Leukocytes: White blood cells, phagocytic cells, defend against microbes
• Platelets: Blood clotting
• Diapedesis: ability to leave the blood vessels and find foreign invaders
• Phagocytosis: engulfing pathogen into cell membrane
• Chemotaxis: The movement of cells in response to chemical stimuli.
• Apoptosis: a form of programmed cell death that occurs in response to a variety of stimuli
• Granulocytes: Contain large granules that stain different colors
• Basophils: No phagocytosis. Release inflammatory chemicals
• Eosinophils: Phagocytic, but not as effective as neutrophils. Responsible for allergies
• Neutrophils: Both Eosinophils and Neutrophils phagocytize pathogens
• Agranulocytes: Monocytes and lymphocytes
• Monocytes: ”wandering” or specialized white blood cells that are the precursors of macrophages
• Lymphocytes: white blood cells that produce antibodies and help the immune system fight infection.
• Macrophage: A type of cell derived from monocytes that engulf foreign particles such as bacteria.
• Differential white blood count: Can signal disease by increased eosinophils, leukocytes, and lymphocytes
• Six stages of Phagocytosis: Chemotaxis, adhesion , Ingestion, maturation, killing, and elimination
• Chemotaxis is when phagocyte moves towards chemoattractant (chemical attractants) released by damaged tissue or microbes
• Adhesion is when phagocyte attaches to surface of pathogen using receptors on its membrane
• Ingestion is when phagocyte surrounds pathogen with pseudopodia and forms phagosome
• Maturation: Lyzomes that break down the invader
• Killing: Lyzomes kill it
• Elimination: Cell expels excess stuff from the cell by breaking down the stuff and eliminating it from the cell.
• Nonphagocytic killing: Eosinophils attack parasites by adhering to surface, and secreting toxins