Mod 7 IQ 10 Flashcards
What are protective barriers in plants
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
What are protective barriers in animals
physical barriers such as
thick fairly tough skin and other epithelial surfaces
chemical barriers include
the pH of the skin, along with body fluids
What are protective barriers in humans
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
What are some adaptations of intercellular pathogens to facilitate entry into the host
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
The response of Eucalyptus to pathogens
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
Physical barriers
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
Cellular level physical barriers
Cell membrane
Nuclear envelope
Compartmental borders
Chemical barriers
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
Physical and chemical changes in the presence of a pathogen
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
What are the three key roles of the inflammatory response
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
What is the result of the inflammatory response
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
What are the chemical changes caused by the inflammatory response
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
What are the first, second and third line of defenses
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
What is the innate immune system
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.
What is the innate immune system made up off
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
What are lymphocytes
non phagoctic cells
T cells and B cells are two different types of lymphocytes responsible for adaptive immune response in the human body,
B and T cells
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 ) .
What does the bone marrow produce in response to infection
more white blood cells
What is the role of macrophages
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
What are neutrophils
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
What does the complement system do
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
What is innate immunity
is naturally present and does not involve a response to an antigen and does not confer long term immunity
what is active immunity
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.
What is passive immunity
is provided when a person is given antibodies
What are antibodies and how do they work
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
What are the disadvantages of Passive immunity
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
What do helper T cells do
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
What do regulatory T cells do
Slow down the workings of the body’s defences so that the immune system ‘calms down’ again after the infectious agent has been destroyed
Killer T cells
Can directly destroy bacteria or cells that have been infected by a virus or have become cancerous
Memory T cells
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
