How do we protect ourselves? Flashcards
What are the functions of the lymphatic system?
Functions of the Lymphatic System
-Fluid balance
o Excess interstitial fluid enters lymphatic capillaries and becomes lymph (30L from capillaries into interstitial fluid, 27L return leaving 3L, called lymph).
-Fat absorption
o Absorption of fat and other substances from digestive tract via lacteals.
-Defence
o Lymphatic system – fights infection. Microorganisms and other foreign substances are filtered from lymph by lymph nodes and from blood by spleen.
Name the anatomy of the lymphatic system
- Lymph
- Lymphatic vessels
- Lymphatic tissue
- Lymphatic nodules
- Lymph nodes
- Tonsils
- Spleen
- Thymus
What is Lymph?
-Water plus solutes from two sources
o Plasma: ions, nutrients, gases, some proteins
o Cells: hormones, enzymes, waste products
-Returns to circulatory system via veins; essential for fluid balance.
What is the function of the lymphatic vessels?
-Carry lymph away from tissues
-Lymphatic capillaries
o More permeable than blood capillaries Epithelium functions as series of one-way valves Found in all parts of the body except nervous system, bone and avascular tissues (without blood vessels - cornea, epidermis).
-Lymphatic capillaries join to form lymphatic vessels
-Lymphatic vessels: have valves that ensure one-way flow (beaded appearance)
-Lymph nodes: distributed along vessels and filter lymph
-Lymphatic trunks: jugular, subclavian, Broncho mediastinal, intestinal, lumbar
-Lymphatic ducts: drain tissues of body and move lymph into major veins
o Right lymphatic duct: drains right side of head, right-upper limb, right thorax
o Thoracic duct: drains remainder of the body
What are the lymphatic tissues & organs?
-Lymphatic organs contain lymphatic tissue (lymphocytes, macrophages, dendritic cells)
o Lymphocytes: B & T cells - white blood cells derived from bone marrow.
o Fine network of reticular fibres. Produced by reticular cells. Act as filter to trap microorganisms and other particles
o May be encapsulated (in a CT capsule)
- Encapsulated- lymph nodes, spleen, thymus
- Nonencapsulated- mucosa-associated lymphoid tissue (MALT). Found beneath epithelium as first line of attack against invaders.
What is diffuse lymphatic tissue & lymphatic nodules?
- Diffuse lymphatic tissue: dispersed lymphocytes, macrophages; blends with other tissues.
- Lymphatic nodules: denser aggregations. Numerous in loose connective tissue of digestive (Peyer’s patches), respiratory, urinary, reproductive systems.
What are lymph nodes, what do they remove and what are they organised into?
-Only structures to filter lymph
-Substances removed by phagocytosis or stimulate lymphocytes to proliferate.
o Cancer cells often migrate to lymph nodes, are trapped there, and proliferate. Can move from lymphatic system to circulatory system spreading cancer through the body.
-Afferent and efferent vessels
-Organized into cortex and medulla with dense connective tissue capsule surrounding.
What are the parts and function of the tonsils?
-Large groups of lymphoid tissue in nasopharynx and oral cavity
-Provide protection against bacteria and other harmful material.
o Palatine (tonsils)
o Pharyngeal (adenoids)
o Lingual
What are the functions of the spleen, what are red pulp associated with & what are white pulp associated with?
-Red pulp associated with veins (75%) – Fibrous network of macrophages and RBCs.
-White pulp associated with arteries (25%) – lymphatic tissue.
Functions
o Monitors blood, detects and responds to foreign antigens.
o Destroys defective red blood cells
o Regulates blood volume
o Limited reserve of RBC
-Can be ruptured in traumatic abdominal injuries.
-Splenectomy.
What is the thymus the site of and what is its location?
- Located in superior mediastinum.
- Cortex (numerous lymphocytes) and medulla (fewer lymphocytes)
- Site of maturation of T cells: many T cells produced here, but most degenerate.
- Those that remain can react to foreign substances.
- Endocrine functions.
What is tonsillitis, lymphoma & hodgkins disease as disorders?
- Tonsillitis – Inflammation of the tonsils – bacterial infection.
- Lymphoma – cancer (benign or malignant) of the lymphoid tissue or cells, often begins in the lymph nodes, immune system suppressed.
- Hodgkin’s disease – Malignancy in lymphoid tissue (malignant B cells). Chemotherapy /radiation
What is Non-hodgkins lymphoma & Bubonic plague as disorders?
- Non-Hodgkin’s lymphoma – any cancer of lymphoid tissue – except Hodgkin’s. Can affect cells, nodes or organs. Young vs Old.
- Bubonic plague (The Black death) – severe bacterial infection (fleas/rats), enlarged lymph nodes, septicaemia.
What is a pathogen, what do they introduce & what do antigenic receptors recognise?
- Pathogen – foreign agents
- Pathogens introduce foreign (non-self) proteins into the body called antigens
- Antigenic receptors on T cells and B cells recognize these foreign proteins as not being “self” (i.e. as being “foreign”, and aims to remove them from the body
What is immunity, what can it distinguish (internal/external) & what are the categories?
-Ability to resist damage from foreign substances and internal threats
-Can distinguish between “self” and “non-self”
o External – micro-organisms e.g. bacteria, virus, fungi, toxins
o Internal – cancer cells
-Categories
o Innate or nonspecific immunity
o Adaptive or specific immunity
-Innate and adaptive immunity are fully integrated in the body
What is the lymphatic systen?
- Transport system for cells of the immune system and antigens (foreign substances/cells) to move around the body.
- Tissues where cells of the immune system “hang out”
