Non-specififc Immune Responses Flashcards
What is the immune system?
The immune system is a group of cells,tissues, organs and mechanisms that defend an organism against pathogens and other foreign substances.
What is a pathogen?
A pathogen = a disease causing organism
What is an immune response?
An immune response is a complex series of specific and non-specific processes involving a range of cells and chemicals§
What are the primary defences?
The primary defences are those that attempt to prevent pathogens from entering the body.
Are the primary defences specific or non-specific?
They are non-specific as they just prevent the entry of the pathogen.
What primary defences do we have?
- the skin
- clotting
- mucous membranes
- stomach acid
- tears/saliva
- nasal hair/ear wax
-expulsive reflex
-inflammation
8 primary defences
What is the body covered with?
The body is covered with skin which is our main primary defence. Skin mainly acts as a physical barrier to prevent the entry of microorganisms.
What is the outer layer of the skin called?
The epidermis
What does the epidermis consist of?
The epidermis consists of layers of cells called KERATINOCYTES
Where are the keratinocytes produced?
Keratinocytes are produced by mitosis at the base of the epidermis.
Where do keratinocytes then migrate to?
KERATINOCYTES then migrate to the surface of the skin
What happens as the keratinocytes migrate?
As the keratinocytes migrate they then dry out and the cytoplasm is replaced by the protein keratin.
What is the process by which keratinocytes migrate and dry out and the cytoplasm is replaced with keratin known as?
The process by which keratinocytes migrate, then dry out and the cytoplasm is replaced by keratin is known as KERTANISATION is tasked about 30 days/
What damage the skin and open the body to infect?
Abrasions or laceration damage the skin and open the body to infect
After abrasions and lacerations occur what must the body do to prevent excess blood loss?
When abrasions and lacerations occur the body must prevent excess blood loss by forming a CLOT
What is a clot?
A clot is a temporary seal that prevents infect and allows time for the repairing of skin.
Blood clotting is a complex process, what does it involve?
Blood clotting involves calcium ions and at least 12 factors called clotting factors
Where are many of these clotting factors released from?
Many of these clotting factors are released from PLATELETS and FROM DAMAGED TISSUE.
What do these clotting factors which are released from platelets and damaged tissue used for?
These factors activate and enzyme cascade that leads to a clot.
What are platelets?
Platelets are a component of the blood
whose function is to stop bleeding
by clumping and clotting blood vessel injuries.
NB:
PLATELETS ARE FRAGMENTS OF CYTOPLASM
That are derived from cells found in the bone marrow that enter the circulation
What are areas such as the airways, the lungs and digestive system protected by?
The AIRWAYS, LUNGS and DIGESTIVE SYSTEM are protected by MUCOUS MEMBRANES.
How many types of cells does the epithelial layer contain?
The epithelial layer contains 2 types of cells which help trap and remove mucus:
1. Mucus-secreting cells = goblet cells, these secrete mucus which traps,microorganisms,dust and pollen
2. Cilia- these are fine hair like organelles which can move in a coordinated fashion to help waft the mucus along.
In the lungs they waft the mucus up to the trachea where it can be swallowed and killed by the acidity of the stomach
Where are cilia found?
Cilia are found inside the trachea, bronchi and large bronchioles
Where are goblet cells found?
Goblet cells are found in large bronchioles
What is the role of stomach acid?
Stomach acid (gastric juice) helps kill pathogens/parasites that enter the stomach
What is the role of tears and saliva?
Tears and saliva help kill bacteria and contain an antibacterial agent (enzymes)
What is the role of nasal hair and ear wax?
Nasal hair and ear wax help trap pathogens/parasites and stops them entering the nose
What is the role of expulsive reflex?
Reflex e.g. Cough which allows you to react to a stimuli that could be dangerous
What specialised white blood cells detect the presence of microorganisms in the tissue?
The presence of microorganisms in the tissue is detected by specialised white blood cells called mast cells.
What is the name of the cell signalling substance which mats cells release once the presence of microorganisms in the tissue has been detected?
Mast cells release a cell signalling substance called HISTAMINE
What is the main effect of histamine?
The main effect of histamine is to cause VASODILATION in capillaries near the site of infection. Due to the histamine the capillaries near the area become leaky.
What is the point of inflammation?
Inflammation means more fluid leaves the capillaries in the area of infection (Causing redness or swelling) and allows phagocytes/neutrophils to leave the blood and enter the surrounding tissue fluid
Also inflammation means more tissue fluid is drained into the lymphatic system. This leads the pathogen towards the macrophages waiting in the lymph nodes and helps initiate the specific immune response.
What type of defence are phagocytes involved in?
Secondary defence - if pathogens do get through the bodys outer defences, they will need to be recognised and destroyed before they cause the symptoms of disease.
Secondary response is involved AFTER the pathogen has entered the body.
How many types of phagocytes are there?
2
Describe neutrophils?
- neutrophils have a multi-lobed nucleus
- neutrophils are manufactured in the bone marrow
- neutrophils are short-lived and often die after taking in and destroying bacteria
- neutrophils travel in blood and often squeeze out of the blood into tissue fluid (when histamine is released)
Describe macrophages?
Macrophages are larger and can therefore engulf a greater number of pathogens
Macrophages are manufactured in the bone marrow
Macrophages travel in the blood as Monocytes
Monocytes tend to settle in the body’s organs particularly the lymph nodes where they develop into macrophages
Macrophages play an important role in specific responses
How are phagocytes able to pass from the blood into the tissue fluid?
They have a lobed/narrow nucleus
They can change shape
They can squeeze/ fit between cells in walls of capillaries
How are phagocytes involved in the non-specific immune response?
Phagocytes engulf and destroy pathogenic cells
They are non specific as phagocytes are able to digest/engulf a range of many different pathogens
How phagocytes work?
Step 1: pathogen is recognised as being foreign due to chemical markers on its outer membrane known as antigens
Step 2: phagocyte attaches to bacteria
Receptor on phagocytes attaches to antigen on bacterium
Step 3: bacterium engulfed - enters phagocyte by ENDOCYTOSIS
Formation of phagosome/phagocytic vacuole
Step 4: lysosomes fuse/move towards phagosome by cytoskeleton
Lysosomes release HYDROLYTIC enzymes/lysins/hydrogen peroxide/free radicals (into phagosome)
Step 5: bacterium is hydrolysed
To amino acids/ sugar/ glucose
Any useful products are absorbed into cytoplasm by diffusion
What is a phagosome?
Phagosome - wrapping of cytoplasm around the pathogen
What can enhance phagocytosis?
Phagocytosis can be enhanced by the action of OPSONINS
What is an opsonin?
An opsonin is any molecule that BINDS to a PATHOGEN and increases/enhances the likelihood of phagocytosis by marking an antigen for an immune response.
Give an example of an opsonin?
antibody
Macrophages play an important role in initiating the specific response to a disease ?
1) a phagocyte engulfs a bacteria
2) parts of the bacteria (antigen) goes to the surface of the macrophage - ANTIGEN PRESENTING CELL
3) the macrophages presents the antigen to a T helper cells
4) The T Helper cell is now activated
