Lymphatics and Immunity Flashcards
When and where does the lymphatic start budding from?
In the 5th week, it starts to bud from the vein development around the subclavian area where it then moves inferior and superior
When are the lymphoid organs developed?
Spleen and thymus are developed before birth and the rest are after birth where there is a build up of lymphocytes which then parallels the immune system.
What is the function of the lymphatic system?
Waste products being flushed out. Drainage and transport of interstitual fluid back into the venous blood circulation. Intestines-absorb food fats and is part of bodys immune system
What do the lymphatic organs produce?
They produce lymphocytes
What are the main roles of the lymphatic system?
To collect and recycle fluid that has leaked out of blood capillaries, to phagocytize bacteria (old red blood cells, impurities such as toxins and cellular waste), to absorb lipids from intestines and production and activation of lymphocytes
What is the formation of a lymph?
The blood in capillary is under high pressure forcing some plasma out through the pores in capillary walls bathing the body cells. The plasma is interstitual fluid (no red blood cells or platelets, few WBC), the lymphatic system collects interstitual fluid in vessels. The fluid is called lymph
What type of tissue is lymphatic tissue and what does it contain?
It is loose connective tissue (reticular) and contains fibres, fibroblasts, macrophages and lymphocytes
Where can lymphatic tissue be found?
Widely distributed but in gastrointestinal, respiratory, urinary and reproductive tracts.
How can lymph tissue be arranged?
In small masses called nodules or nodes
What are lymph nodules?
Small masses of lymph tissue that produces lymphocytes
What do lymph nodules do?
They are distributed to defend the body against disease producing organisms penetrating the lining of the passageways that communicate with the outside of the body
What are Peyers patches and why do they differ from most lymphatic nodules?
Peyers patches are large masses of lymph nodules found in the small intestine. Most lymph nodules are small and solitary but can be found in large clusters
How does lymph get to lymph nodes?
They do not have vessels but may have germinal centres containing immature lymphocytes surrounded by a cortex
What are tonsils in relation to lymphatic system?
Tonsils are lymph nodules found in oral cavity and pharynx. Produce lymphocytes against invading bacteria however this invasion may cause tonsils to swell
Where is the thymus located and what colour is it?
The thymus is located above the heart and behind the sternum between lungs. It is a pinky-grey organ
What are the major lymph node areas?
Temporal, thoracic, inguinal, axillary, abdomen and clavivlarism
Where is the spleen located and how big is it?
It is the largest lymphatic organ at 12cm long and found in abdominal cavity, posterior lateral to stomach and protected by 9, 10 and 11 rib
What does the spleen do?
It removes bacteria, worn out blood cells, platelets and debris from general circulation. Works as extramedullary hemopoeisis occurs by liver and spleen causing enlargement of spleen. Can inflamme due to overworking
What does the thymus do?
Plays key role in immunity and produces t-lymphocytes that respond to disease
Where are b-lymphocytes made?
In the bone marrow
What are the largest central lymph vessels and where do they get lymph from?
Lumbar, jugular and intestinal and take lymph from inner organs, extremities and trunk quadrant
From the trunk, where does lymph drain into?
Either the right lymphatic duct or larger thoracic duct. From the ducts they drain into the venous system at the subclavian vein
What does the thoracic duct drain?
Legs and pelvis, lower trunk quadrant, intestines (cisterna chyli) and left upper quadrant (left side of head)
What does the right lymphatic duct drain?
Right side of head, neck, arm and lungs and right upper quadrant
What is oedema and what can is result in?
Swelling caused by accumulation of large amounts of fluid in intercellular spaces. Its visible and palpable (pitting). If not resolved early, secondary damage to lymphatic system can occur
What can cause oedema?
Cardiac insufficiency, immobility and chronic venous insufficiency
What are the 4 types of insufficiences with oedema?
High volume insufficiency, Low volume insufficiency, Safety valve insufficiency and right cardiac insufficiency (renal disease)
What is right cardiac insufficiency with oedema?
Weak muscles of right ventricle of heart cause blood to be left behind in ventricle, congestion then spreads to right atrium then to vena cava and veins. Venous pressure increases and causes more lymph to produce and less lymph is reabsorbed into veins. Emptying of lymph into veins is difficult due to increased venous pressure and result is reduced transport capacity and increase lymph load exceeding transport capacity and results in congestive heart failure
What is immunity?
The body providing protection against foreign substances including disease producing organisms or pathogens
What are antigens?
Stimulates production of antibodies by an immune responsiveness (bacteria, penicillin, poison ivy)
What are antibodies?
Function of body stimulated by antigens
What is the first line of defence in non specific immunity?
Skin/mucous membranes, keratin (resistance against acids, alkalis and bacterial enzymes), nasal hairs, cillia and urine
What is the second line of defence in non specific immunity?
Phagocytes (nuetrophil/macrophages which eat invading substances by engulfing and destroying), Natural killer cells (destroy cancer and virus infected cells by ordering cell to self suicide), inflammation (removes injurious effects of harmful substances ) and Antimicrobial proteins (interferons-proteins secreted by virus infected cell to protect non-infected cell and complement-proteins that enhance immunity) and fever
What is a fever and what does it do?
High temperature that is set off by pyrogens (chemicals released by leukocytes when they encounter foreign substances). Prompts spleen and liver to hold onto iron and zinc which bacteria needs in order to multiply. Destroys micro-organisms that replicate better at 35 degrees
What are interferons?
Group of proteins produced by certain types of cells that become infected by intracellular parasites, bacteria, fungi or protazoa but mainly viruses. They stimulate other cells to produce antiviral proteins, which prevent the cell from manufacturing macro molecules required by virus. Virus is less effective at infecting cells and also stimulates natural killer cells which destroy cells that have been infected by virus
How do cells distinguish between self and non self?
All cells have MHC (major histocompatibility complex) proteins located on surface which are highly specific for each individual. They act as tags indicating self. When immune cells come in contact with proteins that are not recognisable they start and immune attack against foreign substance. All cells constantly checked for self or not
What are the types of lymphocytes?
B-cells, T-cells and antigen presenting cells
What are Antigen presenting cells and where are they found?
They engulf antigens and present part of it to T cells who will start a cell mediated response or stimulate a humeral response (by triggering B cells). They are found mostly in connective tissue and skin but also macrophages and B cells
What are the types of antibodies? (Gammed)
IgG-most abundant, crosses placenta IgA- found mostly in mucous IgM- first antibody released in blood IgM and IgG-only one that can fix complement IgE- involved in allergies IgD Always bound to B cell surface M-modem and G-gone
How do antibodies bind to antigens to become a complex? (PLAN)
P- precipitate the antigens (make less soluble) and phagocytes can destroy them more easily
L-Lysis- Attract complements that lyse (break down) the complexes
A- Agglutinate. Form clumps so that phagocytes can get to them more easily
N-Neutralise the dangerous sites on antigens that often release toxins to the body until phagocytes get to them
What does HIV mean with cells?
Helper T cells destroyed.
What are the 2 types of immunity on immune response?
Humoral (antibody mediated) immunity and cell mediated immunity.
What is humoral (antibody mediated) immunity?
Activation of B cells requires helper T cell which produce lymphokines that activate B cells. This activation leads to differntiation into plasma cells and formation of memory Bcells . Plama cells produced and secrete antibody specific for antigen. It occurs mainly against extracellular pathogens, encapsulated pathogens and pathogens that produce exotoxin`
What is cell mediated immunity?
Has 2 distinct components helper T cell-mediated immunity and cytotoxic T cell-mediated immunity. Involves T cells
What is helper T cell-mediated immunity?
Macrophages are activated by IFNy produced by helper T cell. Activated helper T cell is aided by activated macrophages mediate cellular immunity and delayed type hypersensitivity. Main defence against intracellular pathogens -fungi and protozoa and may be involved in tumour immunity
What is Cytotoxic T cell mediated immunity?
Destroys virus-infected cells and main defence against viruses. Also destroys tumour cells and cells in tissue graft.
What are the types of immunity on mode of acquirement?
Active and passive
What do b cells mature to?
Become immunocompetent (antigen specific receptors on surface)
What do t cells mature to?
Helper T cells, Cytotoxic cells or other types
Why are immunocompetent lymphocytes special?
They are able to bind to foreign substances
