Immunity Topic 7 1st year Flashcards
What are microbes/pathogens?
Disease causing organisms which can live on or inside our body
Name some examples of microbes
Bacteria
Viruses
Fungi
Name some diseases which these microbes cause
Bacteria : meningitis or tubercolosis
viruses: hepatitis or small pox
fungi: athlete’s foot
Mention a type of beneficial bacteria and where it can be found
Symbiotic bacteria which is found in the large intestine of humans which produces vitamin K and B12
What are the 3 main body barriers which prevent these harmful microbes from invading the body?
3 lines of defence
Primary barriers: These are physical barriers which keep microbes out of the body
Non-specific internal defences: attack “all microbes no matter what it is” and a general response is produced by the body
Specific internal defences: combats specific microbes
Give examples of structures which form part of the 1st line of defence
Skin
mucous membranes
secretions
cilia
Why is the skin an excellent habitat for these microbes to live on the skin?
Because the skin is warm ,moist and has a good source of nutrients for these microbes
How is the skin adapted to prevent the entry of pathogens?
The skin is hardened,slightly acidic and salty and is impermeable to water due to a substance called sebum secreted by the epidermal cells
True or false.
There is beneficial bacteria on the skin.
True.
These beneficial bacteria can even eliminate much more harmful bacteria which are on the skin
True or false
Not every single part of the body has dead keratin impregnated cells which prevent the entry of microbes, because there are several opening present. Therefore the body produces secretions to try and prevent these pathogens from entering the body
True
Give some examples of how the body further protects the body from invading it which forms part of the first line of defence.
1) In the mouth there is the secretion of the lysozyme enzyme to kill any potential bacteria. If the bacteria manage to survive the lysozyme attack the stomach produces hydrochloric acid for additional bacterial breakdown.
2)In the ears there is the secretion of wax.
3) In the nasal cavity globlet cells produce mucous, and the presence of cilia help to beat the mucous containg pathogens in it where they will be sneezed .
4) Eyes contain lysozymes that digest bacteria,keeps the eyes sterile.
If there are any cuts present in the skin, how does the body heal it to ensure that no pathogens can enter it?
Cuts are any unnatural gaps found in the skin. The skin cells will close these gaps with the help of plasma proteins and platelets. The skin cells will also regenerate to dry and heal the wound. The seal will prevent the entry of pathogens
What will happen if the first line of defence is not enough in order to prevent microbes from entering the body?
The second line of defence comes into play
How is the second line of defence divided?
Non-specific immune response
Specific immune response
Describe the specific immune response
The immune response is specific and relies on prior experiences and encounters with the microbe. specific substances are released to kill the microbes
Describe the non-specific immune response
Consists if an inflammatory reaction against the disease. It also includes white blood cells that digest the microbes
What biological term do we use to describe non-specific immune responses?
Passive immunity
What biological term do we use to describe specific immune responses which form part of the 2nd line of defence?
Acquired Immunity
A new-born is born. However initially the immune system of the baby is not yet in full fight mode. Why?
Because the baby received some antbodies from its mother (passive immunity). But then as the baby continues to grow,the immune system of the baby can distinguish between self and non self. This is called active immunity.
How can we further divide the types of “attacks” regarding the non-specific immune responses?
Inflammation
Fever
Phagocytes
Natural killer cells
What is inflammation?
A local response to tissue damage
What causes an inflammation?
It could be caused by microbial invasion, irritants containing harmful chemicals, cuts and other types of physical damage to the tissues.
What chemicals and type of hormone does the damaged tissue release when there is an inflammation?
Chemicals: prostaglandins and
the hormone histamine.
What is the function of histamine and prostaglandins during an inflammation?
They will cause the arterioles to vasodilate to increase the blood flow towards the damaged area. And the permeability of capillaries also increases
What will happen to the capillaries due to the increased permeability?
Larger amount of blood flow, this will also cause swelling, redness and the temperature to rise. This can lead to pain in the damaged area.
What is the purpose of the permeability in the capillaries?
This will allow white blood cells like macrophages and other phagocytic cells to squeeze through the pores to fight the pathogens. Phagocytes will engulft the bacteria and digest them.
What is pus?
The material which ooes out of a healing wound,which consists of dead white blood cells,microbes and tissue debris,they are both living and dead.
How do the white blood cells know that there is a damaged area in the body ?
Because the damaged area and the microbes themselves will release chemicals which are going to attract the macrophages to get to the injured site.
Which types of white blood cells are responsible to carry out phagocytosis?
Phagocytes
Neutrophils and macrophages
What are neutrophils?
Neutrophils are types of phagocytes and they are the first types of white blood cells to arrive on site. They are able to squeeze through capillary walls and tissue spaces.
What are macrophages?
White blood cells that patrol in tissues and can be found in the liver,spleen or lymph nodes.
From which cells do macrophages develop from?
Monocytes
What will the macrophages do when after they have digested the bacteria?
Some breakdown products are presented on the memebrane of the macrophage itself,to stimulate the action of lymphocytes.
Describe more in detail the characteristics of phagocytes
Phagocytes they engulf bacteria and remove debris or dust in the body for example the lungs.
They show ameboid movement (move by their cytoplasm) (ameboid structure and function)
They are able to recognize invading microbes and can detect where tissue damage has occurred.
After some phagocytes broke down the bacteria,what will some phagocytes do with the ingested material?
The phagocytes which have broken down the bacterium, will present the ingested material on the surface of the cell as antigens in order for them to be recognized by other white blood cells called lymphocytes (specific immune response)
Name the structures in a white blood cell
lysosome
nucleus
cytoplasm
cell membrane
(for the phagocytosis diagram)
Very briefly explain what happens in phagocytosis with a food particle
The organism will ingest the food particle
The food particle will form into a food vacuole
Then the lysosome will digest the food vacuole
What are natural killer cells?
They are another type of white blood cell. However they are a type of lymphocyte which look a lot like T and B cells but they are NON-SPECIFIC in their action
What do natural killer cells mainly target?
They are cells which target cancer and viral cells
Natural killer cells secrete chemicals on the membranes of infected cells
True or false
Natural killer cells conduct phagocytosis
FALSE
They secrete chemicals onto the membranes of infected cells.
They will secrete enzymes onto the memebranes of incfected cells,this will cause the membranes to become leaky and it will kill the bacterium