Lymphatic System
Instructions: Read chapter 13 (pp. 254-271). While you are reading, please complete the graphic organizer. This will serve to help you summarize the key points of this system.
Functions:
1. Fluid Balance: pulls fluid from tissues into lymph capillaries to avoid edema.
2.Fat Absorption – taken care of by the lymph capillaries embedded in the intestines (fats and fat soluble vitamins)
3.Defense – WBC’s (Lymphocytes and Macrophages)
Primary Organs and their Roles:
Red Bone Marrow-in the epiphysis of long bones; area where hemopoesis occurs and where B cells differentiate.
Thymus Gland-within the thoracic cavity; superior to the heart; bi-lobed gland responsible for the differentiation of T cells – also produces thymus hormones that help T cells mature. This gland shrinks as you get older which may be why you are more prone to disease as you age.
Secondary Organs and their Roles:
Lymphatic Vessels-contain lymph (fluid) to combat edema – vessels and capillaries – capillaries have simple squamous -these vessels can assist tumors in metastasis
Lymph Nodes-swollen areas of vessels contain T, B cells and macrophages.
Spleen-located near stomach – two areas red and white pulp – full of macrophages and lymphocytes which react to pathogens in the blood and help to clean out old red blood cells.
Lymphatic Nodules-tonsils, peyers patches, and appendix – concentrated area of lymph tissue.
Defense:
Nonspecific
Briefly describe the Barriers to Entry and their link to this system.
Mechanical barriers like mucous membranes in the respiratory system, digestive system etc block pathogens. Oil glands in the integument block bacteria colonization and the acid pH of the stomach kills pathogens that may enter on consumed food.
Describe the Inflammatory Reaction.
Symptoms are redness, heat, swelling, and pain. White blood (Basophils) cells release histamine causing blood vessels to dilate becoming permeable to fluids. Increased blood flow results in red, warm skin. Dilated capillaries cause proteins and fluid to enter tissues causing swelling. Swollen tissues push on nerves resulting in pain.
Neutrophils and Monocytes (monocyte = Macrophages) are stimulated to come to the inflamed area and phagocytose the bacteria and dead tissue due to the trauma.
Natural Killer Cells
Lymphocytes that kill virus-infected cells and tumor cells by cell to cell contact. May also be cells involved in the aging process – may be involved in apoptosis (programmed cell death).
Specific Response to Antigens (Lock and Key systems)
B-cells and Antibody Immunity
B lymphocytes give rise to plasma cells that create antibodies for specific antigens. The body has the ability to recognize its own cells and distinguish it from trespassers. Antibodies are proteins shaped like the antigen receptor and capable of combining with and neutralizing specific antigens on the surfaces of cells.
T-cells and Cell Immunity
Lymphocytes are capable of recognizing an antigen because they have antigen receptors which are plasma membrane proteins that combine with a specific antigen. In this way they can target and connect to invader cells.
Induced Immunity
Define:occurs naturally through infection or is brought about artificially through medical intervention.
Active ImmunityBody creates its own antibodies in response to antigens of invading cells. Vaccines induce this process.
Passive ImmunityIndividual given prepared antibodies. It is a temporary immunity. (Breastfeeding)
Aging and the Lymphatic System
Disappearing Thymus Gland
B cells don’t form clones
Response to vaccines not as good
Questions:
- Describe how the lymphatic system helps maintain homeostasis in the respiratory and cardiovascular systems.
Respiratory: Non-specific defenses like mucous membranes and cilia which trap debris and move it out of the system. Tonsils sit superior to the respiratory passages to trap any inhaled or ingested pathogens. Leukocytes actively create antibodies for any inhaled pathogens which will help fight infection. Inflammatory responses help maintain homeostasis of the sinuses during respiratory illnesses and allergies.
Cardiovascular: Leukocytes in the blood stream identify the foreign antigens and actively create antibodies to attack such antigen. Histamine produced by Basophils increases capillary permeability to allow for inflammatory responses. Blood is moved to sites that need it due to infection.
- Discuss how allergies, tissue rejection and auto immune diseases result.
An allergy is a hypersensitivity to substances that normally do not elicit a response from the body. An immediate allergic reaction is when the body creates an inflammatory response to the foreign antigen on the allergen (pollen).
Tissue rejection occurs because the body does not recognize the antigens on the transplant tissue and the T-cells target the tissue killing it.
Autoimmune disease is when antibodies from a body attack its own cells. It is unknown what causes these. Auto immune diseases are often found in multiples in people that exhibit them. There isn’t a cure, but many can be controlled with drugs.
- Describe what happens to a person who has an autoimmune disease.
Their antibodies attack the bodies own cells as in Diabetes where the cells in the Islets of Langerhans are destroyed by the T-cells causing Insulin to not be made by the body.