Topic F - autoimmune disorders and the eye Flashcards
what is the body defense/immune system?
- like “army” in the body to fight “disease” by attacking/kill them. protection against pathogens and antigen
- when it senses these foreign invaders, it sends out an army of fighter cells to attack them. it can identify threats, mount attacks, eliminate and remember them
- it can tell the difference between foreign cells and own cells
- immune system is made up of: organs, tissues, cells, molecules
- *two types : non-specific (innate) and specific (adaptive)
what are the meanings of pathogen, antigen and antibodies?
pathogen
= bacteria/virus/microorganisms
eg covid-19
antigen
= toxin/foreign substances/protein found on the surface of pathogens
- both are a threat to the immune system and stimulates immune response
antibodies
= a protein-like substance produced by the immune system in response to and destroy/counteract a specific antigen (pathogen)
what is the clinical insight of bacteria vs virus ?
the 2 most common pathogens affecting human
bacteria
- very small, single-cell organism, does not have a nucleus and other complex cellular organelles
- their DNA is concentrated
- *causes diseases by releasing toxins (poisons), enzymes that damages healthy cells or enters/destroy healthy cells
- treatment: antibiotic
virus
- ultrasmall particles of nuclei acid and protein (>1000x smaller than bacteria)
- not organisms, not alive
- simply composed of DNA or RNA molecule coated by protein
- *causes diseases by dismantling metabolic machinery of host cells and destroys them
- attaches to cells surface receptor and penetrates into the cell,taking over the cell DNA and metabolic machinery,causing the cells to replicate 200x/1000x of viruses and burst the cell to destroy - then it attacks other cells
- antibiotic is not effective in treating viral infections
*** important
what are the 5 non-specific(innate) immune systems?
(before pathogen enters bloodstream, no memory )
~not directed against a specific pathogen
- mechanical barrier
- chemical actions
- phagocytosis
- inflammation
- fever
*** important
what is the mechanical barrier immune system? and what are their methods of providing non-specific resistance against disease?
intact mucous membrane
- has closely arranged cells retard entrance of pathogens ; not as effective as intact skin
mucus
- traps pathogens in digestive and respiratory tracts
saliva
- washes pathogens from oral surfaces
tears (when blinking)
- washes pathogens from the surface of the eyes
urine
- washes pathogens from urethra
*** important
what is the chemical action immune system? and what are their methods of providing non-specific resistance against disease?
components :
-acid pH of the skin, gastric juice, interferon, lysozyme
- tears, saliva, nasal secretions, perspiration will produce enzymes called lysozyme that kills bacteria
- gastric juice has low PH and an enzyme called pepsin also kills microbes
- lymphocytes and macrophages produce interferon to kill viruses
- interferon is now used as an injection to kill viruses
*** important
what is the phagocytosis immune system? and what are their methods of providing non-specific resistance against disease?
- is the engulfing and destruction (by destroying) or microorganisms, damaged cells, and cellular debris by granulocytic leukocytes and macrophages (large leukocytes)
- it “swallows” microorganisms etc and workers with helper T cells
- this happens in the spleen, lymph nodes, liver, brain , bone marrow
*** important
what is the inflammation immune system? and what are their methods of providing non-specific resistance against disease?
- in the event of infection, cells release chemicals such as histamine and prostaglandin which causes dilation of arterioles and increases the permeability of capillaries of the affected area. it increases blood flow and produces redness and heat, and tissue swelling due to the movement of fluids from capillaries
- white blood cells (WBC)/leukocytes, are attracted to the affected area
- neutrophil and macrophages actively phagocytize the pathogen and damaged cells
- the accumulated mass of living and dead leukocytes, tissue cells, and bacteria may form pus
- the continued action of leukocytes brings the infection under control and the dead pathogens/cells are cleaned up by phagocytes. new cells are now produced by cell division to repair the damage
*** important
what is the fever immune system? and what are their methods of providing non-specific resistance against disease?
- the abnormally high body temperature in an event of serious infections
- it inhibits the growth of certain pathogens and increases rates of body processes, including those that fight infection
what is the process of phagocytosis?
- macrophages and granulocytic leukocytes are a type of phagocytes, which will then kill and ingest the pathogens via a process known as phagocytosis
- if the situation does not turn better, helper T cells will release cytokines, a type of hormone, to the lymph nodes, which will activate the immune response
*** important
what is the specific (adaptive) immune system?
(after pathogen entering the bloodstream, has memory)
- this is also called “immunity/immune response”
- it is directed at specific pathogens and foreign cells
- it produces a specific cell and substance to attack a specific invader
- for the second encounter, the immune response will be faster and stronger
eg B cells and T cells
** important
what are the B cells and T cells? and what are their functions?
B cells
= anti-body mediated immunity
- attacks antigen by producing antibodies
T cells
= cell-mediated immunity
- attack pathogen/foreign cells by chemical/physical means (with phagocytosis)
what are B and T cells ( B and T lymphocytes)
- lymphocytes are formed in red bone marrow during fetal development
- they will mature and turn into B and T cells and participate in immunity
- B and T cells will be carried by the blood to lymphatic organs eg lymph nodes, spleen, tonsils where they are divide and multiply and are then release back into the blood
- about 75% of circulating lymphocytes are T cells and 25% are B cells (thousands/millions of them)
- they have specific receptors to recognize antigens/foreign cells and are named differently
- ~ B cells, memory B cells, helper T cells, cytotoxic T cells, memory T cells etc
what are the immune responses?
- when an antigen is encountered, it stimulates B and T cells to produce clones that attack and destroy antigen -> primary immune response, memory cells are produced (able to recognize the antigen)
- if another invasion of the same antigen occurs, the memory B and T cells recognize it and launch a -> secondary immune response (faster and stronger)
antigen recognition -> T/B cells activated -> clone formation and memory cells -> action
*** important
what are the immune responses of the cell-mediated immunity/T cell activation?
- antigen recognition
- T cells (Tc or Th) binds to the antigen and are activated. they develop a memory of their antigen in case it appears again - clone formation
- the activated T cell divides by itself and form clone cells (Tc or Th) and memory cells (Tm) - action
- Tc directly attacks and destroys pathogen
- Th binds itself to antigen, is activated and releases cytokines, which promotes the activity of B and Tc cells, activates phagocytosis/macrophages in the event of inflammation and fever
- Tm cells launch a secondary response (stronger and faster) if the antigen reappears
