Mod 7 IQ 10

Question 1

What are protective barriers in plants

Answer 1

physical barriers 
such as thick cell walls, 
thick cuticles and the presence of a secondary cell wall or thick bark, 
while chemical barriers include 
antimicrobial compounds

Question 2

What are protective barriers in animals

Answer 2

physical barriers such as
thick fairly tough skin and other epithelial surfaces
chemical barriers include
the pH of the skin, along with body fluids

Question 3

What are protective barriers in humans

Answer 3

Skin mechanical unbroken skin protects other tissues
The surface of the body covered by microbes which as physical barriers to reduce the area available for pathogens to attach
Mucous membrane traps pathogens
Cilia beat in one direction to sweep mucus containing pathogens and small particles out of the lungs
Chemical barries (acid) pH on the skin discourages the growth of microbes the stomach juices are highly acidic (pH 2 )
Thick mucus lining makes it difficult for microbes to colonize the stomach

Question 4

What are some adaptations of intercellular pathogens to facilitate entry into the host

Answer 4

some bacteria enter host cells by phagocytosis like tuberculosis which has adapted to survive and replicate inside macrophages
Fungi use camouflage and shedding bits of its cell wall to avoid being detected

Question 5

The response of Eucalyptus to pathogens

Answer 5

Physical barriers 
	Thick cuticle 
	Thick bark 
	Waxy leaves 
	Dry leaf surfaces 
	Vertically hanging leaves prevent the formation of moisture on the leaf which provides some protection from water molds
Chemical barriers  
	Stored oils function as performed chemical defenses, not only against defoliating animals but as antifungal and antibacterial agents or for priming of defenses in both the host and neighboring plants 

The formation of barrier zones in new tissue produced by the vascular cambium these zones protect the healthy sapwood from damage by separating it from the adjacent or damaged tissue; in some Eucalypts these barrier zones contain gum

The development periderm, which separates damaged tissue from healthy tissue prevents the spread of disease(s) secretion of any protective gums that seal the wound from further infection

Question 6

Physical barriers

Answer 6

 Epithelial surfaces e.g. thick, dry and /or scaly skin
 Mucous membranes of internal epithelia helps prevent pathogen from adhering to surfaces
 Amphibians and fish have mucous covering their skin

Question 7

Cellular level physical barriers

Answer 7

 Cell membrane
 Nuclear envelope
 Compartmental borders

Question 8

Chemical barriers

Answer 8

Antimicrobial substances produced by the epithelia e.g. antibacterial enzyme is secreted in saliva and tears.
Acid pH of the stomach and digestive enzymes Antibacterial and antifungal peptides (defensins) produced in the lower intestinal tract ( antimicrobial peptides play an important role in the immune defenses of animals, including insects)
At a cellular level, chemical barriers include plasma membrane of cells and lysosomes

Question 9

Physical and chemical changes in the presence of a pathogen

Answer 9

recognised by phagocytes called macrophages. Macrophages and neutrophils recognise, ingest and destroy pathogens, macrophages and neutrophils produce a number of toxic chemicals that help kill the engulfed microorganism, the macrophages are activated to release cytokines. Cytokines along with other chemicals such as histamine set up the inflammatory

Question 10

What are the three key roles of the inflammatory response

Answer 10

To bring plasma proteins and phagocytes to the site of infection to help kill the pathogen
To provide a physical barrier to prevent further spread if the infection and make the host aware of the infection
To promote the repair of damaged tissue

Question 11

What is the result of the inflammatory response

Answer 11

 An increase in the diameter of blood vessels
 An increase in permeability of blood vessels
 An increase in temperature of the tissues and body temperature

Question 12

What are the chemical changes caused by the inflammatory response

Answer 12

 Toxic hydrogen peroxide superoxide and nitric oxide produced by phagocytes help kill the pathogen
 Production of cytokines(that set up inflammatory response)
 Secretion of adhesions during the inflammation response
 Secretion of chemicals that bring about blood clotting

Question 13

What are the first, second and third line of defenses

Answer 13

The first line of defense (non-specific )
Physical, chemical and microbial barries e.g. intact skin, lysozyme in tears and normal flora
The second line of defense (Non-specific)
Inflammation
white blood cells (neutrophils and macrophages)
The third line of defense (specific resistance )
White blood cells (B and T lymphocytes)
Antibodies

Question 14

What is the innate immune system

Answer 14

The innate immune system is non-specific. Therefore its main role is to prevent pathogens from entering and spreading in the body. The system provides a frontline defense by engaging pathogens directly and acting immediately. It is unaltered in its ability to fight the same or different pathogens time and time again.

Question 15

What is the innate immune system made up off

Answer 15

The innate immune system in the human body is made up of:
 the skin and all mucous membranes (epithelial surfaces), which form external and internal barriers
 defense cells formed from white blood cells (leukocytes) such as phagocytes
 various substances circulating in the blood and in body fluids, such as cytokines and anti-microbial peptides( defensins)
 complement system
 natural killer (NK) cells; if natural killer cells

Question 16

What are lymphocytes

Answer 16

non phagoctic cells

T cells and B cells are two different types of lymphocytes responsible for adaptive immune response in the human body,

Question 17

B and T cells

Answer 17

Those lymphocytes that continue their development are called B cells ( B for bone marrow) . Those that migrate from an immature state from the bone marrow and continue their development in thymus are called T cells ( T for thymus ) .

Question 18

What does the bone marrow produce in response to infection

Answer 18

more white blood cells

Question 19

What is the role of macrophages

Answer 19

 Macrophages are the first phagocytes to encounter pathogens in the tissues but they are soon reinforced by neutrophils. Macrophages and neutrophils can recognize pathogens by means of cell surface receptors that distinguish self from non-self

Question 20

What are neutrophils

Answer 20

 Neutrophils are short-lived cells that die soon after phagocytosis. Dead and dying neutrophils are a major component of the pus that forms in some infections

Question 21

What does the complement system do

Answer 21

The complement system enhances (complements) the immune defense mechanism
 Clear microbes and damaged cells
 Disrupt membranes of microorganisms
 Mark pathogens, making them more attractive for phagocytes
 Attract macrophages and neutrophils from the blood
 Activate local phagocytes and local mast cells that release granules containing histamine
 Help trigger an inflammatory response
 dissolve the cell walls of bacteria so they lose fluids and minerals, resulting in their death
 Fight viruses directly by destroying the virus envelopes, or indirectly by destroying cells infected by a virus

Question 22

What is innate immunity

Answer 22

is naturally present and does not involve a response to an antigen and does not confer long term immunity

Question 23

what is active immunity

Answer 23

immunity to a disease is achieved through the adaptive immune system which produces memory cells after the primary contact with the pathogen (antigen) remembers hence if a second infection occurs the immune system will immediately recognize it releasing necessary antigens needed to fight it.

Question 24

What is passive immunity

Answer 24

is provided when a person is given antibodies

Question 25

What are antibodies and how do they work

Answer 25

Antibodies work by
 neutralizing the pathogen by either attaching directly to the surface through the antigen-antibody complex or by attaching to the toxins produced by bacteria
 Activating other defense cells(e.g. phagocytes in the tissue and mast cells) which is responsible for any allergic reactions; phagocytes can fight pathogens better if they are packed with antibodies around them
 Activating the complement system

Question 26

What are the disadvantages of Passive immunity

Answer 26

Difficult and costly to produce

• Antibodies must be harvested from the blood of hundreds or thousands of human donors
• Or they have to be taken from immune animals which cause serious allergic reactions
• Given via intravenous injection which is more time consuming and complicated than vaccines
• Does not create long-lasting memory cells

Question 27

What do helper T cells do

Answer 27

Stimulate the production of antibodies by B cells and their dispersal through the bloodstream and therefore the entire body, meaning that the infection can be fought on many fronts

Question 28

What do regulatory T cells do

Answer 28

Slow down the workings of the body’s defences so that the immune system ‘calms down’ again after the infectious agent has been destroyed

Question 29

Killer T cells

Answer 29

Can directly destroy bacteria or cells that have been infected by a virus or have become cancerous

Question 30

Memory T cells

Answer 30

Remember information about the pathogen and have the ability to recognise the original invading antigens for a longer time; memory T cells can pass on this information immediately if there is another infection, resulting in a quick response