Thymus • One of the few glands to shrink with age, 70 grams to 3 grams • Contained within a capsule • Invaginations of the capsule are called trabeculae and form thymic lobules just like the RLN • The dark outside layer is the cortex and where the initial T cell programming occurs • The lighter center called the medulla is the final program area for maturing pre-T cells occurs
Thymus continued • Other cells in the thymus include dendritic cells derived from monocytes and act as antigen presenting cells • Also epithelial cells function to secrete thymic hormones to assist in T cell programming, and form the framework of the thymus • Thymic corpuscles are located in the medulla and manufacture keratohyaline and keratin of unknown function
Spleen • Largest lymphatic organ • Also contains a capsule with trabeculae • In this case the outside layer is the stroma containing reticular and fibroblast cells • The parenchyma contains the splenic artery of white pulp that houses a high number of lymphocytes (B and T cells) • The splenic vein forms the red pulp containing RBCs, macrophages for phagocytosis of old RBCs, and 1/3 rd of all the bodies platelets • Look up the word splenunculi
Non-specific disease defense mechanisms • AKA innate • First line of defense that is both physical and chemical • Does not need programming centers
Normal microbiota • Takes up: – Space – Nutrients – Gases like oxygen – Vitamins • Release bacteriocins – The vast majority are toxic to other organisms such as other microbes and of course humans – The few that are not toxic to humans can possibly be used as antibiotics
Skin • Skin is a pressure vessel • Shedding completely every two weeks • Oil and sweat is bacteriostatic • The skin is waterproof • The skin is dead • Clotting stops bleeding but also entraps microbes
Interesting facts • Microbes vary on area and person • Some are coccoid others are bacilli • Hand washing with antibacterial is a risk for infection • 8 hour to recolonize • Triclosan is a trichlorinated bi-phenolic
Eyes • We always cry • Drains into the acid pit • Tears flush • Tears also contain lysozyme • Lysozyme disrupts the formation of bacterial cell walls undergoing division • Lysozyme is also found in saliva and mucous in general
Ear wax • Cerumen is long chain fatty acids • Also an as yet unknown agent that is bacteriostatic • Interesting note is that genetically people are either hard of soft wax secretions
Gastrointestinal • Acid and alkaline environment • Many digestive enzymes also kill microbes • Initial microbiota is important • Oral antibiotics have made a mess of the microbiota of a lot of people
Respiratory system • At a high risk: because the lungs are: living, thin, high surface area, and exposed • Conchae AKA nasal turbinates • Mucous lined • Smart cilia • Vibrissae • Epiglottis • High number of RLNs and macrophages
You've reached the end of your free preview.
Want to read all 98 pages?