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immunity or resistance
is the ability to ward of damage or disease through our defenses
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susceptibility
vulnerability or lack of resistance
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innate (non-specific) resistance
refers to defences that are present at birth. It acts against all microbes in the same way. It does not have a memory component, that is it can not recall a previous contact with a specific microbe. Designe to prevent microbes from gaining access into the body
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adaptive (specific) immunity
refers to defences that involve specific recognition of a microbe once it has breached the innate immunity defences. It is based on a specific response to a specific microbe, that is it adapts or adjusts to handle a specific microbe. It is slower to respond but it does have a memory component. It involves lymphocytes
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lymphatic system
consists of a fluid called lymph, vessels called lymphatic vessels that transport the lymph, a number of structures and organs containing lymphatic tissue and red bone marrow, where stem cells develop into the various types of blood cells including lymphocytes
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lymph
after interstitial fluid passes into lymphatic vessels it is called lymph. The major difference between the two is location
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lymphatic tissue
is a specialized form of reticular connective tissue that contains large numbers of lymphocytes
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Functions of the lymphatic system
drains excess interstitial fluid and drains it to the blood, and transports dietary lipids, carries out immune responses
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lymphatic capillaries
these tiny vessels which are located in the spaces between cells, are closed at one end. they converge to form larger ones which resemble veins in structure but have thinner walls and more valves. They have a unique one way structure that allows interstitial fluid to flow in but not out.
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lacteals
in the small intestines, specialized lymphatic capillaries called this, carry dietary lipids into lymphatic vessels and ultimately into the blood
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chyle
the presence of these lipids causes the lymph to appear creamy white, elsewhere lymph is pale
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lymphatic vessels
thinner walls with more valves. At intervals, lymph flows through lymph nodes, encapsulated bean shaped organs consisting of b-cells and t-cells
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thoracic duct
the main duct for the return of lymph to blood
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right lymphatic duct
receives blood from the upper right side of the body. From here the lymph drains into venous blood at the junction of the right internal jugular and right subclavian veins
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primary lymphatic organs
are the sites where stem cells divide and become immunocompetent, that is, capable of mounting an immune response. The primary organs are red bone marrow and the thymus
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secondary lymphatic organs and tissues
are the sites where most immune responses occur. They include lymph nodes and the spleen and lymphatic nodules (follicles). All are considered organs except the lymphatic nodules
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lymph nodes
located along lymphatic vessels are 600 bean shaped nodes. they are scattered throughout the body. A lymphatic organ
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thymus
is a bilobed organ located in the mediastinum between the sternum and aorta. A lymphatic organ
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spleen
is the largest single mass of lymphatic tissue in the body. It is located in the left hypochondriac region between the stomach and diaphragm.
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white pulp
is lymphatic tissue consisting mostly of lymphocytes and macrophages arranged around branches of the splenic artery. Blood flowing in enters these and B and T cells carry out immune functions
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red pulp
consists of blood-filled venous sinuses and splenic cords that contain red blood cells, lymphocytes, macrophages, plasma cells.
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lymphatic nodules
are egg shaped masses of lymphatic tissues that are not surrounded by a capsule.
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mucous-associated lymphatic tissue
Because they are scattered through out the mucous membranes of connective tissue lining the GI tract, urinary and reproductive tracts and the respiratory air ways, lymphatic nodules in these areas are referred to as this.
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tonsils
usually five of them, which form a ring at the junction of the oral cavity and oropharynx and at the nasal cavity and nasopharynx. They participate in immune responses against inhaled or ingested foreign substances
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pharyngeal tonsils or adenoid
only one. it is embedded in the posterior wall of the nasopharynx
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palatine tonsils
two of them. They lie at the posterior region of the oral cavity. One on either side. these are the tonsils usually removed
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lingual tonsils
located at the base of the tongue, may also require removal during a tonsillectomy
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