They Lymphatic System

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They Lymphatic System Body Defenses

• Human Anatomy Physiology
• Unit 6

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Lymphatic Vessels

• The function of lymphatic vessels is to pick up
  the excess tissue fluid (called lymph clear
  water) and return it to the blood stream
• These vessels form a one-way system and only flow
  towards the heart
• Lymph capillaries spider web through the body
  tissues to collected leaked fluid

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Lymphatic Vessels

• Like veins, lymphatic vessels have valves to
  prevent the fluid from flowing backwards
• While, blood stays relatively free of bacteria,
  viruses and cancer they can easily enter the
  lymphatic vessels
• This creates a problem because bacteria, viruses
  and cancer can then easily travel to other parts
  of the body
• To solve this lymph nodes are throughout the body
  to examine and cleanse (if needed) by the
  immune system

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Lymph Nodes

• They work along with the immune system to protect
  the body
• As the lymph is transported to the heart it makes
  several stops through lymph nodes to be checked
  before it reaches the heart
• A collection of lymphocytes are located in lymph
  nodes to respond if a foreign substance is
  detected
• This is why most of us will get swollen glands
  during an active infection

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Lymph Nodes

• Most lymph nodes are kidney shaped and less than
  one inch long
• There are two regions of lymph nodes in the body
  the right lymphatic duct and the thoracic duct
• The neck and head drain into the right duct and
  the rest of the body goes through the thoracic
  duct (within these regions are thousands of lymph
  nodes)

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Other Lymphoid Organs

• Spleen helps to filter the blood and destroy
  worn-out red blood cells to they can be
  reabsorbed by the liver
• The thymus gland functions at peak performance
  during youth produces thymosin a hormone to
  create certain lymphocytes to heighten their
  protective roles
• Tonsils their job is to trap foreign pathogens
  before they enter the body

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Body Defenses

• Every second of everyday hostile bacteria,
  viruses and fungi are trying to invade our system
• There are two approaches to body defenses
  nonspecific and specific defense system

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Nonspecific Defense System

• This system responds immediately to ALL foreign
  substances
• First line of defense is the skin, mucous
  membranes and secretions of the skin
• The second line is phagocytic cells,
  antimicrobial proteins and an inflammatory
  response

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Nonspecific Body Defenses

• Examples of Surface Membrane Barriers
• Skin is a physical barrier
• Mucous membranes line all body cavities to act as
  a physical barrier
• Vaginal secretions of adult females are very
  acidic
• The stomach produces HCl to kill pathogens
• Saliva can kill some pathogens
• Tiny hairs in the nasal cavity trap inhaled

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Nonspecific Body Defenses

• Examples of Cells and Chemical Defenses
• A fever will help increase the rate at which
  defense cells work
• Phagocytes will engulf a foreign particle
• Natural killer cells will target any foreign
  particle and attack the cell's membrane (the cell
  will then shortly disintegrate)
• Inflammatory response will trigger redness, heat,
  swelling and pain
• The redness and heat is caused by the increase of
  blood to the site, the swelling and pain is
  caused by the bodys attempt to prevent movement
  and promote healing

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Specific Defense System

• This is commonly called the immune system
• The most important immune cells are they
  lymphocytes and macrophages
• A proper working immune system will protect the
  body from bacteria, viruses, transplanted organ
  or blood and even our own cells that have turned
  against us

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Specific Body Defenses

• The two main types of immune cells are B-cells
  and t-cells
• Within the B-cell family and T-cell family there
  are several types and each have their own job
• Memory B-cells
• Memory T-cells
• Helper T-cells
• Plasma cells
• Suppressor T-cell

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Specific Body Defenses

• Active immunity can occur two ways naturally or
  artificially through immunizations
• The immune system has the ability to remember
  some diseases
• Passive immunity occurs when the protection is
  borrowed
• For example, a mother to fetus or through breast
  milk (the immune system does not remember using
  passive immunity)

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Disorders of Immunity

• Allergies
• The body fights off a perceived threat that would
  otherwise be harmless (basically, the immune
  system overreacts)
• Allergies are rarely fatal however, when the
  reaction enters the blood stream it circulates
  rapidly through the body
• This is call anaphylactic shock and can be fatal

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Disorders of Immunity

• Immunodeficiency (both congenital and acquired)
• Basically, there is little to no immune response
• Severe combined immunodeficiency disease (SCID)
  congenital
• Acquired immune deficiency syndrome (AIDS)

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Disorders of Immunity

• Autoimmune Diseases
• Multiple sclerosis (MS)
• Myasthenia gravis
• Graves disease
• Type 1 diabetes mellitus
• Systemic lupus erythematosus (commonly called
  lupus)
• Rheumatoid arthritis

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