What are pathogens
Pathogens are organisms that cause disease.
Pathogens can be either bacteria, fungi, protozoa, viruses.
Bacteria- single celled organisms that replicate frequently and release toxins that can cause swelling and inflammation.
Fungi- Eukaryotic organism that releases mycelium under the sjin surface , which enters tissues and disrupts their function
Viruses- aren’t a real cell, acellular, enters a cell and takes over the host cell , then is released causing the cell to break from the virus or budding through the cell membrane
Protozoa- attached to intensine lining anf prevents them from absorbing nutrients.
Immune system can distinguish between body cells (self) and pathogens/foreign materials ( non self) and foreign materials causes an immune response to become produced.
Two types of responses: specific + non specific
Types of transmission
Direct contact- flus/colds through hand shaking, MRSA
Airbourne- Flus/colds influenza
Covid, measles
Foodbourne-salmonella
Waterborne-cholera
Vectorborne- Malaria, yellow fever
Transplacental - syphillis, HIV/AIDS, gonnorehea
Innate immunity pt1.
This is the immunity thats present from birth, includes first and second line of defence.
Intact sjin- acts as a mechanical barrier , and prevents the entry of pathogen
Sjin secretions- sweat/ sebum which makes the epidermal surface acidic, this prevents the growth of any bacteria.
Nasal hair-Traps any pathogens and filters air
Cillia-propels mucus away from digestive and respiratory tracts
Mucus- traps microorganisms in resp and digestive tracts
Gastrict juice- contains hydrochloric acid + protein digesting enzyme
Saliva- lubricates mouth and contains lysozyme
Lacrimal secretions (Tears)- lubricates eyes and contains lysozyme and which destroys microorganisms
Urine- acidic, inhibits the growth of bacteria
Vaginal activity- acidic, inhibits the growth of bacteria aswell as fungi
Macrophages
Macrophages are another type of phagocyte, these cells travel as monocytes and when it reaches the lymph node it becomes mature.
Macrophages engulfs a pathogen anf then pushes the antigen to the surface, so it can become an antigen presenting cell, so it is able to trigger adaptive innunutity
Why does a second line of defence happen
- innate immunity
Happens when the first line of defence is brecahed , so chemical defences are made
Neutrophils
Most common type of phagocyte to be released during infection
Neutrophil binding to opsonin on the pathogen, pathogen is then engulfed bt the neutrophil -phagosome
Lysosomes fuse to the phagosome and releases lyrtic enzymes into i
After digested , harmless products are then absorbed
Types of leukocytes
Neutrophils- involved in phagocytosois, common attached to the walls in blood vessells + prevents pathogens entering
Monocytes- mature into macrophages which they carry phagocytosis of any dead cell to become an antigen presenting cell.
Eosinphills- involved in combatting allergies, worjs by trapping substances ehen moving to inflamed areas + releases enzymes from the cyptoplasm to destroy pathogens
Lymophcytes- concentrated within the lymphatic system
B cells - can differentiate into B memory cells/antibody cells
T cells can either become T-killer cells whete they bind to cells and would kill the cell or it becomes regulatory or memory cells - stimulating B cells into becoming plasma cells
Basophila - A type of white blood cells that are responsible for co-ordinating Innune responses such as the release of heparin- prevents blood clotting
Histamine- vasodilation
Mast cells - involved in first line of defence , located in the ephitlelial cells and causes inflammation responses when foreign substances are detected
Adaptive immunity/specific innunnity
Refere to the long term immunological memory, takes considerably long
B-lymphpcytes can divide and differentiate into B-plasma cells which secretes specific antibodies
T helper cells can either differentiate into T-killer cells or T memory cells
T helper cells can also help activate B cells.
B cells can only be activated by T independent antigen sometimes + can respond to the antigen independently
T dependent antigens can only stimulate
