Unit 9: The Lymphatic and Immune Systems NURSING PHYSIOLOGY (NRSG237)

Transcription

1 Unit 9: The Lymphatic and Immune Systems Dr. Moattar Raza Rizvi NURSING PHYSIOLOGY (NRSG237) Functions: Transports Excess Interstitial Fluid Back to Bloodstream Lymphatic vessels collect lymph from loose connective tissue Carry fluid to great veins in the neck Fluid flows only toward the heart 1

2 Functions: Distributes hormones, nutrients, and waste products Functions: Houses Lymphocytes 2

3 Components of the Lymphatic System Main structures of the lymphatic system Lymphatic vessels Main components of the immune system Lymph Lymphocytes Lymphoid Nodules (Tonsils) Lymphoid Organs 3

4 1. Lymph capillaries Smallest lymph vessels Orders of Lymphatic System First to receive lymph 2. Lymphatic collecting vessels Collect from lymph capillaries 3. Lymph nodes Scattered along collecting vessels 4. Lymph trunks Collect lymph from collecting vessels 5. Lymph ducts Empty into veins of the neck Lymph Capillaries Lymphatic Trunks Lymphatic Collecting Ducts Lymphatic Ducts Lymphatic Vessels 4

5 Lymphatic vessels The walls of lymphatic vessels are similar to those of veins but have thinner walls and more valves. Lymph vessels in the skin follow veins. Lymph vessels in the viscera follow arteries. Lymph vessels are NOT found in avascular tissue, CNS, parts of spleen and red bone marrow. Lymphatic Capillaries Located near blood capillaries Receive tissue fluid from CT Increased volume of tissue fluid Minivalve flaps open and allow fluid to enter Highly permeability allows entrance of Tissue fluid Bacteria, viruses, and cancer cells 5

6 Location and Structure of Lymphatic Capillaries Lacteals Lacteals specialized lymphatic capillaries Located in the villi of the small intestines Receive digested fats Fatty lymph chyle 6

7 Lymphatic Collecting Vessels Accompany blood vessels Composed of the same three tunics as blood vessels Contain more valves than veins do Helps direct the flow of blood Lymph propelled by Bulging of skeletal muscles Pulsing of nearby arteries Tunica media of the lymph vessels Lymph Trunks Lymphatic collecting vessels converge Five major lymph trunks Lumbar trunks Receives lymph from lower limbs Intestinal trunk Receives chyle from digestive organs Bronchomediastinal trunks Collects lymph from thoracic viscera Subclavian trunks Receive lymph from upper limbs and thoracic wall Jugular trunks Drain lymph from the head and neck 7

8 Overview of the Lymph Nodes, Trunks The Lymphatic Trunks 8

9 Lymphatic System Right lymphatic duct Right subclavian vein Left subclavian vein Lymph capillaries converge to become collecting vessels and end up as either Thoracic duct or right lymphatic duct Thoracic (left lymphatic) duct Cysterna Chyli Lymphatic Ducts The right and left (thoracic duct) lymphatic duct empties directly into the left subclavian vein 9

10 Lymphoid Nodules Tonsils and Peyer s patches These organs don t filter but do contain macrophages & lymphocytes. Peyer s patches Found in small intestine Small organs known collectively as GALT (gutassociated lymphatic tissues). Prevent pathogens in the respiratory and digestive tract from going through the mucous membrane lining Lymphoid Nodules (Tonsils) The pharyngeal tonsils are found in the Nasopharynx Figure

11 Tonsils 11

12 Lymphoid Organs Primary lymphatic organs - site of B and T cell production bone marrow - produces B cells, pre-t cells thymus gland pre-t cells migrate to thymus gland and mature in thymus gland Secondary lymphatic organs - site of most immune responses lymph nodes, spleen surrounded by connective tissue capsule lymphatic nodules not surrounded by capsule Lymphoid Organs largest 12

13 Bone Marrow: Lymphopoiesis Lymphocytes are later also produced in thymus, spleen and tonsils B- and T- Lymphocytes 13

14 B and T cells Thymus Gland Located in pleural cavity Between sternum, heart 2 lobes Atrophies with Age Composed of cortex and medulla Functions strictly in lymphocyte maturation Thymus Gland Largest lymphatic organ in a child is thymus gland 14

15 Spleen largest mass of lymphoid tissue in body Left side of body between stomach/diaphragm thick fibrous capsule organ function: immune function removal of worn out or damaged RBC s storage of platelets production of RBC s during fetal life Lymphatic Tissue - Spleen Spleen White pulp produce lymphocyte (B and T cells) which carry out immune function. Red pulp functions concerning RBCs; phagocytize senescent (old) cells 15

16 Lymph Nodes Cleanse the lymph of pathogens Human body contains around 500 Lymph nodes are organized in clusters Lymph Nodes 16

17 Microscopic Anatomy of a Lymph Node Fibrous capsule surrounds lymph nodes Trabeculae connective tissue strands Lymph vessels Afferent lymphatic vessels carrying fluid towards lymph node Efferent lymphatic vessels: carrying fluid away from the lymph node Cranial cavity is an area where lymph nodes is not present Function of a Lymph Node Function Lymph percolates through lymph sinuses Most antigenic challenges occur in lymph nodes Antigens destroyed and activate B and T lymphocytes 17

18 Immune System The Immune System - includes all parts of the body that help in the recognition and destruction of foreign materials. White blood cells, phagocytes and lymphocytes, bone marrow, lymph nodes, tonsils, thymus, and your spleen are all part of the immune system. 2 Type of Immunity: Innate & Acquired Innate/Natural/ Nonspecific present from birth operates against any substance not enhanced by prior exposure Acquired/Adaptive/Specific defense mechanisms tailored to individual pathogens enhanced by prior exposure 18

19 Innate Immune System: First Line of Defense Refers to various PHYSICAL, CHEMICAL, and CELLULAR attributes that collectively represent the first line of defense against infectious disease. Skin acts as a barrier to invasion Sweat has chemicals which can kill different pathogens. Tears - have lysozyme which has powerful digestive abilities that render antigens harmless. Saliva also has lysozyme. Mucus - can trap pathogens, which are then sneezed, coughed, washed away, or destroyed by chemicals. Stomach Acid destroys pathogens WBC: Macrophages/Lymphocytes White blood cells called macrophages trap and engulf cell debris and pathogens. Other white blood cells, called Lymphocytes - are a type of white blood cell capable of producing a specific immune response to unique antigens. They produce antibodies which are chemicals that mark pathogens for destruction. 19

20 Lymphocytes Immunity is the result of the action of two types lymphocytes, the B lymphocytes and the T lymphocytes. B cells become plasma cells and produce antibodies that are secreted into the blood and lymph. T cells attack the cells that have antigens that they recognize. Active Immunity Active Immunity occurs when when one makes his/her own antibodies. This type of immunity is long term. Getting the disease : If you get an infectious disease (like Chicken Pox), often times, that stimulates the production of MEMORY cells which are then stored to prevent the infection in the future. 20

21 Vaccination A vaccination artificially acquired active immunity A vaccination is an injection of a weakened form of the actual antigen that causes the disease. The injection is too weak to make you sick, but your B lymphocytes will recognize the antigen and react as if it were the "real thing". Thus, you produce MEMORY cells for long term immunity. Passive Immunity Passive Immunity occurs when the antibodies come from some other source. This type of immunity is short term. Breastmilk : Milk from a mother's breast contains antibodies. The baby is acquiring passive immunity. These antibodies will only last several weeks. 21

22 Gamma Glubulin Gamma Globulin: A Gamma Globulin shot is purely an injection of antibodies to provide temporary immunity. You might receive an Gamma Globulin shot if you travel outside of the country. Artificially acquired passive immunity could be the result of gamma globulin injection. Antibodies An antibody is a protein produced in response to an antigen. Antigens are macromolecules that elicit an immune response in the body. The most common antigens are proteins and polysaccharides. 22

23 Antibodies Antibodies - Immunoglobulin There are 5 classes of antibodies: IgG most abundant; about 80% of all antibodies in the blood; can cross the placenta from mother to fetus, giving newborns immune protection IgA makes up 10-15% of antibodies in the blood; levels decrease during stress IgM makes up 5-10% of antibodies in the blood; first secreted by plasma cells IgD makes up only about 0.2% of antibodies in the blood IgE makes up less than 0.1% of all antibodies in the blood; involved in allergic reactions 23

24 1. What is the functions of Lymphatic system? 2. Give the order of Lymphatic system? 3. Where can you find the lymphatic capillaries? 4. Where do the lymphatic fluid flows, towards the heart or away from the heart? 5. What are lacteals? 6. Which has more valves the veins or lymphatic collecting vessels? 7. Explain the 5 major types of lymphatic trunk found in human? 8. Write short notes on lymphoid organs and their functions? 9. Give the location and function of thymus gland? 10.What is the function of spleen? 11.What is the function of lymph node? 12.Write the difference between innate and acquired immunity? 13.Write the components of first line of defense in innate immunity? 14.Write the function of B-cells and T-cells? 15.What is gama globulin? 16.Write the 5 classes of antibodies and their function? 24