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 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 (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:

  1. Describe how the lymphatic system helps maintain homeostasis in the respiratory and cardiovascular systems.
  2. Discuss how allergies, tissue rejection and auto immune diseases result.
  3. Describe what happens to a person who has an autoimmune disease.

Inflammatory Response:

  1. Histamine (protein complex) causes tissue capillaries to become more permeable.
  2. Increased blood flow to enlarged capillaries causes skin to become red and warm.
  3. Capillaries cause proteins and fluids to escape into nearby tissues- puts pressure on exposed nerves. (causes pain!)
  4. WBC’s engulf pathogens contained within the fluids (pus)

Symptoms  Redness, swelling, pain, heat at the site, itchiness

3 Effects of inflammation temporary repair, barrier against pathogens; retard the spread of pathogens into surrounding tissues; mobilization of local and systemic defenses of the body.