KIN 3304 1nd Edition Exam 3 Study Guide Lectures 18 21 Chapter 23 The Lymphoid System pg 607 The Vaccine Wars Link http video pbs org video 1479321646 Lecture 18 October 13 The Lymphatic System has several components Lymph the fluid connective tissue transported by this system o Consists of Interstitial fluid that resembles blood plasma but with less proteins Lymphocytes Macrophages Lymphatic vessels the vessels that carry lymph o Originate in the peripheral tissues o Deliver lymph to the venous system o Run parallel to blood vessels Lymphocytes the cells in the liquid o Responsible for immune response Lymphoid Organs produce lymphocytes Lymphoid Tissues adjust the composition of lymph There are lymph nodes found throughout the body and they are easily palpable during infection and disease Exercise can help the immune system There are 3 primary functions of the Lymphoid System 1 Produce maintain and distribute lymphocytes 2 Maintain normal blood volume and eliminate variations in the chemical composition of the interstitial fluid 3 Provide an alternate route for the transport of hormones nutrients and waste products 1 Lymphocytes are produced within the spleen thymus and bone marrow There are primary and secondary classifications The thymus and the bone marrow are the primary lymphoid organs Although in mice the spleen is considered primary a Primary lymphoid structures are the thymus and the bones marrow They are responsible for developing and maturing lymphocytes So T cells originate in the bone marrow and then go to the thymus to get educated b Secondary lymphoid structures are where most immune responses begin This is where lymphocytes divide to produce more of the same type Secondary structures are located at the front lines where invading bacteria are first encountered such as lymph nodes and tonsils Thymus Is at its maximum size during puberty and decreases in size thereafter The functional cells are replaced by connective tissue fibers This degeneration process is called involution Involution increases susceptibility to novel pathogens It has a blood thymus barrier that is similar to BBB and prevents leakage of cells It is separated into 2 thymic lobes a right lobe and a left lobe The septa divided the thymus into little compartments known as lobules The lobules contain an outer cortex and a central medulla o The outer cortex is where lymphoid stem cells divide rapidly that produce daughter cells that mature and migrate to the medulla During maturation any daughter cells that are too sensitive to normal antigens are destroyed because it is highly selective and about 2 survive selection There is such thing as a nude mouse that has no thymus which means no immune system SCID severe combined immunodeficiency in which an example is the bubble boy that had no protection Spleen Largest lymphoid organ Attached to the stomach by the gastrosplenic ligament 3 Functions o Removes abnormal blood cells through phagocytosis o Stores iron by recycling broken down red blood cells o Initiates immune responses by B cells and T cells 2 The BP at the proximal end of a systematic capillary is 35 mm Hg and this BP forces water and solutes out of the plasma and into the interstitial fluid About 3 6 L day of blood volume enters the interstitial fluid each day This helps put H2O back into the blood supply a Lymphedema is when a lymphatic vessel is blocked or if it is damaged Drainage will slow or even stop which leads to swelling This is why some people wear sleeves to pump fluid 3 It also functions as an alternate route for hormones nutrients waste immune cells cytokines and etc For example lipids absorbed by the digestive tract will be carried to the blood stream by lymphatic vessels versus being absorbed across capillaries Lymphatic Capillaries form a complex network within the peripheral tissues They differ from vascular capillaries in several ways They are larger in diameter They have thinner walls because their endothelial cells lack a continuous basal lamina They have an irregular outline They have anchoring filaments that help keep passageways open during increasing pressure They have overlapping endothelial cells that are not tightly banded that act as a one way valve Lymphatic Capillaries absorb interstitial fluid and dissolved solutes but they also absorb any viruses or anything abnormal such as bacteria or cell debris that are present in damaged or infected tissues This is why lymphatic capillaries contain evidence about the health of the surrounding tissue There are two types of Lymphatic Collecting Vessels Superficial Lymphatics o Travel with superficial veins and are found in these locations In the subcutaneous layer next to skin In the loose connective tissue of mucus membranes that line the digestive respiratory urinary and reproductive tracts In the loose connective tissues of serous membranes that line the pleural pericardial and peritoneal cavities Deep Lymphatics o They accompany the deep arteries and veins o They collect lymph from skeletal muscles and organs TQ Know the distribution of lymphoid tissues and lymph nodes Cervical LN monitor lymph of the head and neck Axillary LN filter lymph arriving at the truck from the upper limbs In women the axillary nodes also drain lymph from mammary glands Popliteal LN filter lymph arriving at the thigh from the leg o Inguinal LN monitor lymph arriving at the trunk from the lower limbs Thoracic LN receive lymph from the lungs respiratory passageways and mediastinal structures Abdominal LN filter lymph arriving from urinary and reproductive system The lymphoid tissue of Peyer s Patches the intestinal LN and the mesenterial LN receive lymph originating from the digestive tract Lymphomas are malignant tumors that consist of cancerous lymphocytes or lymphocytic stem cells There are about 61 000 cases per year in the US and is very common in dogs Hodgkin s Diseases o Accounts for 1 of 7 lymphoma cases It is common in the ages of 15 35 and over 50 The reason for this pattern is unknown Even though the cause of this disease is unknown an infectious agent probably a virus may be involved Non Hodgkin s Lymphoma NHL o This is when there are abnormalities in chromosomes 85 of the time NHL is associated with this Figure 23 4 pg 611 Look at the type of drainage of the thoracic duct Lymphocytes are the primary cells of the lymphoid system and are responsible for specific immunity They respond to Invading organisms bacteria viruses Abnormal body