Immunity- pathogens and immunity

Question 1

are microorganisms always harmful? give an example

Answer 1

-no
-some can even be beneficial e.g. many types of bacteria and fungi are used in decomposition

Question 2

what are 4 types of microorganisms?

Answer 2

-bacteria
-fungi
-Protoctista
-viruses

Question 3

what is the term used to describe bacteria that is harmful?

Answer 3

-pathogen

Question 4

what happens if a pathogen gains entry to the body?

Answer 4

-it can cause significant harm or even death

Question 5

what is the bodies primary defense mechanism against these pathogens?

Answer 5

-try to prevent entry which is the body’s first line of defense

Question 6

what is the body’s secondary defense mechanisms?

Answer 6

-specific and non specific response

Question 7

what does non specific defense mechanism mean?

Answer 7

-these are not specific to individual types of pathogens

Question 8

what is an example of a non specific defense mechanism?

Answer 8

-phagocytosis

Question 9

what does specific immune response mean?

Answer 9

-this type of response does distinguish between individual pathogens and the response is tailored to the specific pathogen at hand

Question 10

how long does specific immune response take and why is this?

Answer 10

-it takes a loner time to work compared to non specific but tend to provide long term immunity

Question 11

what type of white blood cell is involved with specific immune response?

Answer 11

-lymphocytes

Question 12

what are the 4 natural barriers to pathogen entry?

Answer 12

-an outer protective covering(skin)
-the enzyme lysozyme
-epithelial lining covered in mucus e.g. respiratory tract
-hydrochloric acid in the stomach

Question 13

why is the skin a natural barrier to pathogen entry? when is the skin not an effective barrier?

Answer 13

-the skin provides a tough physical barrier that most pathogens cannot penetrate
-its not effective when its punctured e.g. cut or if its not in its healthy condition

Question 14

what are the three liquid in which the enzyme lysozyme is secreted in?

Answer 14

-tears
-saliva
-sweat

Question 15

how is the enzyme lysozyme used as a natural barrier to pathogen entry?

Answer 15

-its anti-bacterial as it is able to hydrolyze bacteria cell walls
-tears can also wash away debris and pathogens from the front of the eye which is very delicate

Question 16

how is epithelial lining which is covered in mucus an effective barrier to pathogen entry?

Answer 16

-the mucus traps pathogens and prevents them penetrating the underlying membranes

Question 17

what is a structure in the respiratory tract that prevents pathogen entry?

Answer 17

-cilia which sweep the pathogens back up the trachea

Question 18

how is hydrochloric acid in the stomach an effective barrier to pathogen entry?

Answer 18

-this kills most pathogens that are in food
-it provides a very low pH that denatures the enzymes of the pathogens

Question 19

what white blood cells are involved in phagocytosis?

Answer 19

-phagocytes

Question 20

what do capillaries do as part of the inflammatory response?

Answer 20

-the capillaries in the area affected begin to leak plasma
-infected areas become swollen with dead pathogens and cell debris (pus)
-inflamed areas appear red due to increased blood flow to the area

Question 21

inflammation causes the area to become hot, why is this good?

Answer 21

-the raised temp helps reduce infection by denaturing enzymes in the pathogen

Question 22

what are the 2 types of phagocytes involved with phagocytosis?

Answer 22

-polymorphs which are the first to arrive
-macrophages which develop from monocytes and are larger and longer lived than the polymorphs

Question 23

what are the 6 steps of phagocytosis?

Answer 23

-phagocyte moves to pathogen as its attracted by the chemicals it produces
-the phagocyte membrane invaginates to enclose the pathogen
-as pathogen is engulfed, the invaginated phagocyte membrane forms a vesicle around the pathogen
-lysosome move to vesicle and fuse with it
-hydrolytic enzymes within lysosome are released into the phagosome, these enzymes hydrolyze/ digest the pathogen
-the soluble digested products are absorbed into the cytoplasm of the phagocyte

Question 24

how is specific immune response triggered?

Answer 24

-the responses are triggered by the body being able to recognize foreign cells

Question 25

what are the two types of cells in the body?

Answer 25

-self and non self

Question 26

what are non self tissues?

Answer 26

-cells that are not recognized by the body, if detected the body will produce an immune response

Question 27

what part of non self tissues does the body recognize as foreign? what type of molecule mostly are these? what is the general term to describe these?

Answer 27

-a cluster of molecules that form part of the cell surface membrane that are recognized as foreign
-they are often proteins but can also be polysaccharides, glycolipids or glycoproteins
-antigens

Question 28

why is the immune response specific to different non self tissues?

Answer 28

-because different pathogens have different antigens

Question 29

why are lymphocytes used in specific response to tissues?

Answer 29

-lymphocytes have a receptor on its cell surface membrane that is complementary in shape to the antigen
-like lock and key theory

Question 30

what is the definition of an antigen?

Answer 30

-chemicals/ molecules capable of producing a specific immune response

Question 31

how do lymphocytes know what is self and non self?

Answer 31

-millions of lymphocytes with millions of receptors that are complementary to antigens

Question 32

why is self specific immune response a slow process? (fetal example)

Answer 32

-in foetus these lymphocytes make contact with other foetal self cells
-the lymphocytes that are complementary in shape with foetal cells are switched off so that by the time the baby is born the functional lymphocytes that remain are those that are not complementary to self cells
-because there are millions of these lymphocytes remaining there is only a few of each type so this is the reason why specific immune response is slow