The Lymphatic System & Immune System Flashcards
What is the structure of the lymphatic system?
- lymph
- lymphatic capillaries
- lymphatic vessels, trunks and ducts
- lymph nodes (glands)
- lymphatic organs
- lymphatic nodule
Where are lymphatic nodules found?
- GI tract
- respiratory airways
- urinary tract
- reproductive tract
- tonsils
- Peyer’s patches )in the ileum of small intestine)
- appendix
Lymphatic nodules
= mucosa-associated lymphoid tissue strategically positioned to protect the body from pathogens (inhaled, digested or entered vis external openings).
Where is the thymus gland, and what is its purpose?
- located in mediastinum behind the sternum and lungs
- produces thymosin hormone for development of T cells
Lymph nodes (glands)
= filters the lymph before it returns to the bloodstream; also produce lymphocytes for immune response
Lymphatic vessels, trunks and ducts
= carry lymph from lymphatic capillaries through a number of lymph nodes and into large vessels (called trunks and ducts)
Lymphatic capillaries
= close-ended vessels with larger diameter than blood vessels that permits fluid into them but not out of them (found throughout body except CNS, splenic pulp and bone marrows).
Where is the spleen, and what is its purpose?
- located in abdomen behind the left part of the stomach
- doesn’t filter the lymph, instead it filters and stores platelets and blood as well as lymphocytes
- largest single mass lymphatic tissue
Lymph
= clear water derived from interstitial fluid, which contains proteins, lipid, foreign particles (bacteria) and cell debris from damaged tissues and lymphocytes.
What are the (4) functions of the lymphatic system?
- drains interstitial fluid
- transportation of dietary lipids
- protection against invasion
- transports clear, straw-coloured fluid from interstitial spaces surrounding to the blood
What are the lymphoid structures in humans?
- thymus
- spleen
- red bone marrow
- cervical lymph nodes
- auxiliary lymph nodes
- inguinal lymph nodes
- Peyer’s patches
What are common pathologies of the lymphatic and immune system
- Chronic fever of unknown origin
- Recurring fever with night sweats and weight loss
- Anaphylaxis – severe allergic reactions
Antibody-mediated (humoral) immune response (AMI)
= antibodies bind to antigens and inactivate them
(e.g.; B cells develop into plasma cells which secrete antibodies which binds onto antigen and destroys it.)
Common response to body fluids and pathogens such as bacteria that have multiplied in body fluids.
Cell-mediated (cellular) immune response (CMI)
= ’cells attack cells’ e.g., CD8+ T cells reproduce into killer cells which leave lymphatic tissues to seek out and destroy antigens (fungi, parasites, viruses and some cancer cells).
What are the 2 types of immune response?
- cell-mediated (cellular) immune response (CMI)
- antibody-mediated (humoral) immune response (AMI)
What are the 2 types of T cells?
CD4+ cells
CD8+ cells
T cells
= develop in red bone marrow and migrate to thymus glands to mature; T cells develop antigen receptors
B cells
= matures in red bone marrow; develop into plasma cells and secretes antibodies
What are the 2 types of lymphocytes?
- B cells
- T cells
Fever
= abnormally high body temperature caused by toxins released by microbes. Increase in temperature intensifies the effects of body’s own antimicrobial substances, inhibits microbial growth and increases the growth of tissue repair
Natural killer cells (NK cells)
– type of lymphocytes that can kill variety of microbes as well as tumour cells
- found in spleen, red bone marrows, lymph nodes and blood.
What are the 2 main types of phagocytes?
- neutrophils
- macrophages
What are some examples of chemical barriers to disease (non-specific)?
- Sebum
- Perspiration
- Gastric juices (e.g: hydrochloric acid)
- Vaginal secretions
What are (4) non-specific resistance of disease
- mechanical barrier
- chemical barriers
- inflammation
- fever
Phagocyte
= a cell that engulfs or digests microbes which includes macrophages and some types of white blood cell
Pathogen
= disease-causing microorganism
Microbe
= microorganisms (e.g: bacteria, fungus, virus, protozoa)
What are some examples of mechanical barriers to disease (non-specific)?
- The skin
- Mucous membranes – traps microbes and moves it away from vital areas
- Lacrimal apparatus – produces tears to wash away microbes and dirt
- Saliva
- Urination, defecation and vomiting
Macrophage
= scavenger cells that engulfs and destroys microbes
Lymphocyte
= type of white blood cell involved in immunity (e.g: B cells and T cells)
Inflammation
= body’s response to tissue damage
Antigen
= foreign substance in the body
Antibody
= specialised protein that destroys specific antigen
Epidemiology
= the study of how diseases spread and affect populations and how to control them
What does the first line of defence of innate immunity against pathogens consist of?
- skin
- mucous membranes
What does the second line of defence of innate immunity against pathogens consist of?
- antimicrobial proteins
- natural killer cells
- phagocytes
What are substances that are recognised as foreign and provoke immune responses known as?
antigens
What are the (8) steps involved in cell-mediated immune response to an exogenous antigen?
- Antigen processing by dendritic cells, macrophages, or B cells
- Migration of antigen-presenting cells to lymphatic tissue
- Presentation of antigen to helper T cells
- Recognition of antigen fragments associated with MHC-II molecules by T-cell receptors
- Co-stimulation and activation of helper T cells
- Proliferation and differentiation of helper T cell to produce a helper T cell clone
- Secretion of cytokines such as interleukin-2 by activated helper T-cells
- Activation of cytotoxic T cells
- Elimination of invaders through the release of granzymes, perforin, granulysin, or lymphotoxin or by attraction and activation of phagocytes
Red bone marrow
produces pre-T cells and B cells found in flat bones and epiphyses of long bones
Thymus
responsible for the maturation of T cells
Lymph nodes
- encapsulated bean-shaped structures located along the length of lymphatic vessels
- contain T and B cells, macrophages, and the follicular dendritic cells
- filter lymph
Spleen
the single largest mass of lymphatic tissue in the body
- consists of red and white pulp
Mucosa-associated lymphatic tissue
lymphatic nodules associated with mucous membranes of the digestive, urinary, reproductive and respiratory systems
Lymphatic nodules
nonencapsulated clusters of lymphocytes
Tonsils
clusters of lymphatic nodules involved in immune responses against inhaled or ingested foreign substances
Active helper T cells
- secrete cytokines as co-stimulators
- display CD4 proteins
Cytotoxic T cells
recognise foreign antigens combines with MHC-I molecules on the surface of body cells infected by microbes, some tumour cells, and cells of a tissue transplant, display CD8 proteins
Memory T cells
programmed to recognise the reappearance of previously encountered antigen
B cells
differentiate into plasma cells that secrete specific antibodies
NK cells
- lymphocytes that have the ability to kill a wide variety of infectious microbes plus certain spontaneously arising tumour cells
- lack antigen receptors
Phagocytes
ingest microbes or any foreign particulate matter; include neutrophils and macrophages
Antigen-presenting cells
process and present exogenous antigens, include macrophages, B cells and dendritic cells
Where is the cubital lymph node?
lies above the medial epicondyle of humerus
