Anatomy Chapter 12 Lymphatic System and Body Defenses PDF

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Lymphatic System and Body Defenses Lymphatic System – consist of two semi-independent parts: (1) meandering network of lymphatic vessels and (2) various lymphoid tissues and organs scattered throughout the body *Osmosis – movement of water into greater concentration* ~The hydrostatic and osmotic pressures operating at the capillary beds force fluid out of the blood at the arterial ends of the beds and cause most of the expelled fluid to be reabsorbed at the venous ends ~ ~ Lymphatic vessels is to form a elaborate drainage system that picks up this excess tissue fluid, now called lymph (clear water), and returns it to the blood ~ Right Lymphatic Duct – drains the lymph from the right arm and the right side of the head and thorax Thoracic Duct – receives lymph from the rest of the body; both ducts empty the lymph into the subclavian vein on their own side of the body Lymph Nodes – helps the body by (1) removing foreign material such as bacteria and tumor cells from the lymphatic stream and (2) producing lymphocytes that function in the immune response *L ymphadenopathy - a disease affecting the lymph nodes* * Lymphadenitis – inflammation of the lymph nodes; infected * *Macrophages – within the lymph nodes in which engulf and destroy bacteria, viruses and other foreign substances in the lymph before it is returned to the blood* ~ The outer part of the node, its Cortex, contains collections of lymphocytes called Follicles, many of which have dark-staining centers called Germinal Centers~ ~These centers enlarge when specific lymphocytes (the B Cells) are generating daughter cells called Plasma Cells which release/produces antibodies ~ ~ The rest of the cortical cells are lymphocytes “in transit”, the so-called T Cells that circulate continuously between the blood, lymph nodes and lymphatic stream performing their surveillance role ~ ~ Phagocytic macrophages are located in the central Medulla of the lymph node ~ Spleen – is a soft, blood-rich organ that filters blood - *Largest among all lymphatic organ - *Cemetery of dead/abnormal cells *Splenomegaly - abnormal enlargement of the spleen* *Hepatomegaly - abnormal enlargement of the liver* The Immune System Innate (nonspecific) defense mechanism 1st line Defense Skin Mucous Membrane Secretions of skin and mucous membranes

2nd line Defense Phagocytic cells Antimicrobial proteins The Inflammatory response

Adaptive (specific) defense mechanism 3rd line Defense Lymphocytes (B & T) Antibodies Macrophages

Thymus Gland – is a lymphoid mass found low in the throat overlying the heart - *if it persists it can cause cancer Tonsils – are small masses of lymphoid tissue that ring the pharynx (the throat), where they are found in the mucosa Tonsillitis – inflammation of the tonsils and congested with bacteria Mucosa-Associated Lymphatic Tissue (MALT) – acts as a sentinel to protect the upper respiratory and digestive tracts from the never-ending attacks of foreign matter entering those cavities * Typhoid Fever - an infectious bacterial fever with an eruption of red spots on the chest and abdomen and severe intestinal irritation*

~ The body defenders against these tiny but mighty enemies are two systems, called the innate and the adaptive defense systems, together they make up the immune system ~ Innate Defense System (non-specific defense system) – responds immediately to protect the body from all foreign substances, whatever they are Adaptive Defense System (specific defense system) – mounts the attack against particular foreign substances ~Most important of the immune cells are the lymphocytes and macrophages~ ~The body’s first line of defense against the invasion of disease-causing microorganisms is like the skin and mucous membranes~ Protective Secretions: 1. Acidic pH skin secretions 2. Stomach mucosa 3. Saliva and lacrimal fluid contains lysozome 4. Sticky mucus ~Second line of defense, the body uses an enormous number of cells and chemicals to protect itself, and these defenss rely on the destructive powers of phagocytes and natural killer cells~ ~A phagocyte, such as a macrophage or neutrophil engulfs a foreign particle much the way an amoeba ingest a food particle~ Natural Killer (NK) cells – police the body in blood and lymph, and are a unique group of lymphocytes that can lyse and kill cancer cells and virus-infected body cells well before the adaptive arm of the immune system is enlisted in the fight~ Inflammatory response – is a nonspecific response that is triggered whenever body tissues are injured 4 Cardinal signs of Inflammation: heat - color swelling - tumor

pain- dolor

redness - rubor

When cells are injured, they release inflammatory chemicals, including histamine and kinins that (1) cause blood vessel in the involved area to dilate and capillaries to become leaky (2) activate pain receptors, and (3) attract phagocytes and white blood cells to the area *Chemotaxis – movement of an organism in response to a chemical stimulus; attracts move of inflammatory cells* Diapedesis – a process when neutrophils are squeezing through the capillary walls *Abscess – swollen* *Pus - mixture of dead or dying neutrophils; nana* Antimicrobial Proteins – enhances the innate defense either by attacking microorganisms directly or by hindering their ability to reproduce Complement – refers to a group of at least 20 plasma proteins that circulate in the blood in an inactive state Opsonization – a term that refers to an immune process where particles such as bacteria are targeted for destruction by an immune cell known as a phagocyte Interferon – can be a defense mechanism; interferon molecules diffuse to nearby cells and bind to their membrane receptors Fever – abnormally high temperature, and is a systemic response to invading microorganisms Pyrogens – chemicals secreted by white blood cells and macrophages exposed to foreign cells or substances in the body ~Bacteria require large amounts of iron and zinc to multiply, but during fever the liver and spleen gather up these nutrients, making them less available~ These 1. 2. 3.

landmark experiments revealed 3 important aspects of the adaptive defense” It is antigen specific It is systemic It has “memory”

Humoral Immunity – also called antibody mediated immunity, is provided by antibodies present in the body’s “humors” or fluids

Cellular Immunity- also called cell mediated immunity; lymphocytes themselves defend the body immunity because the protective factor is living cells Antigen – any substance capable of mobilizing our immune system and provoking an immune response Nonself – foreign intruders Self-antigens – don’t trigger an immune response in us, they are strongly antigenic to other people Incomplete antigen (hapten) – troublesome small molecule Penicillin Reaction – the immune system mounts such a vicious attack that the person’s life is endangered...