Bio 275 Central Piedmont Community College Lecture Homework 4 Word document titled HW4 is the assignment.Other Documents and powerpoint are the study mater

Bio 275 Central Piedmont Community College Lecture Homework 4 Word document titled HW4 is the assignment.Other Documents and powerpoint are the study materials that should be used to answer the questions.Please stick the lecture material as she is very particular about this. Unit 3 Lecture 2: Human Defenses
FA19
Human Defenses (ch18)
We have talked about these microbes; described their structures and basic functions of the structures. We have
talked about how they can help us stay healthy and what is involved in their ability to cause disease. Now we turn
our attention to how our body defends itself from these invading microbes.
Levels of Defense:
We find that our defenses can be divided into 3 levels: surface level, non-specific internal level and specific internal
defenses.
Surface Level Defenses:
I.
The first level of defense is the surface level defenses. We have talked about them throughout the
semester, but we will list them to help you keep them contained. There are 3 surface level defenses;
Structural barrier such as your skin, mechanical barriers such as your mucociliary system and
biochemical barriers. Examples of the biochemical barrier can include body secretions like the salts and
lysozymes in your tears. Lactoferrin is another example that is found in your secretions. It inhibits the
formation of biofilms by chelating iron. The microbes need iron to create surface motility essential for
aggregating into biofilms. (Isn’t it interesting to see that bacterial cells need iron… hmm, so do we. We
use it for different functions, but you can see a competition for iron within our bodies once they have
invaded, right?)
Non-specific Internal Defenses
II.
The 2nd level of defense, non-specific internal defenses includes 4 mechanisms; inflammation,
phagocytosis, complement system and interferon. These defenses begin when the first line of defense
has been overcome by the invading microbes.
Four mechanisms:
1. Inflammation is our body’s reaction to injury or infection. Inflammation activates and co-ordinates the other
interior defenses. As you have studied or know by experience, inflammation symptoms manifest as pain,
redness, heat and swelling. Inflammation must be stimulated (or turned on). This happens by several different
molecules such as bacterial by-products, complement fragments and/or histamine. The process of
inflammation begins once one of these molecules (also known as mediators) triggers the capillaries to dilate.
This increases the blood supply to the inflamed tissue. Next the increased blood flow to the area causes
erythema or redness and warmth. The endothelial cells that make up the capillary vessel itself allow
leukocytes (white blood cells) to leave the capillaries and enter the inflamed tissue. Now we find edema or
swelling and pain due to the increased fluid and cells in the area pushing on the pain centers in the tissue (this
is a bit of review from anatomy).
2. Phagocytosis involves the leukocytes we just mentioned. There are several types of leukocytes. We will mention
just 3 of them. Macrophages are phagocytes that also produce granules that they can release. The releasing of the
granules is called degranulation. These granules are toxic chemicals to kill the invading cells and also are used as
inflammatory mediators. Neutrophils are granule producing phagocytes that are designed to attack bacteria.
Eosinophils are leukocytes that also produce granules that when released, are toxic to protozoans, fungi and
worms. These cells will not do phagocytosis. They are designed to defend the body against these eukaryotic
parasites and these parasites are too big for the eosinophil to engulf. The steps in phagocytosis include:
o
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Activation of the leukocyte by inflammatory mediators
Chemotaxis – chemicals that draw the leukocyte to the infected area
Recognition and Opsonization – the phagocyte must recognize which cell they are to attack. Once they
recognize the cell, they have to be able to get a hold of the cell. This occurs when another protein
molecule called an opsonin attaches to the surface of the microbe and/or the leukocyte. The opsonin is
like a piece of double stick tape. Your text may refer to them as linking molecules that bridge the 2 cells.
Once the phagocyte has a hold of the microbe (by using the opsonin) they ingest the microbial cell.
The phagocyte now kills the microbe and digests it.
Lastly, the phagocyte expels any indigestible debris.
3. The complement system is a set of 30 different proteins that our body produces. The system of proteins has 3
main functions: They produce inflammatory mediators, they produce opsonins needed by the phagocytes in
phagocytosis and they form a Membrane Attack Complex that lyses cells. The system works like a cascade
effect (or like the falling of dominoes). As with the other non-specific internal defenses, this system must be
activated before these functions appear. This cascade of events can be activated in 2 different ways. We call
them pathways. One path is called the Classical pathway. This path is activated by an antigen-antibody
complex. An antigen is a molecule that provokes a response from a leukocyte. In this case, the antigen is
attached to the microbe’s surface. An antibody is a protein molecule produced by our B cells in response to a
specific antigen. Antibodies (for our class) look like inverted Y shaped molecules. ( What is a complex?) Here we
see that our non-specific defense is dependent and interactive with our specific internal defenses – our immune
system. The other pathway is called the Alternative path. It is activated when 4 appropriate molecules (4
specific proteins that are part of the set of 30 proteins) come together on the surface of the cell. It does not
require the antigen-antibody complex. Both pathways will activate more inflammation and produce opsonins
for phagocytosis. The last part of the cascade is known as the Cytolysis. Multiple complement proteins set
themselves on the surface of the cell in a circle called the Membrane Attack Complex. The complex punches a
hole in the cell (lysing and killing the cell).
4. The 4th mechanism of the non-specific internal defenses, Interferon, helps us with viral infections. We will
mention only two classes of interferons: alpha interferon and beta interferon. When a virion enters our body and
infects a host cell, the infected cell is triggered to produce and release a molecule called Interferon. The interferon
then contacts surrounding healthy cells and triggers the healthy cells to produce anther protein called anti-Viral
Protein. The infected host cell has been taken over and forced to produce new virions (remember this from the last
test material?). The new virions are released and then move to the surrounding cells and infect them. The cells that
contain the anti-Viral Protein will not synthesize new virions. The anti-viral protein inhibits viral synthesis.
When we discovered this mechanism, we thought we had discovered our greatest defense. But we quickly also
found that interferon is toxic especially to the heart, liver, kidneys and red bone marrow. Interferon is also effective
for only a short time. When we tried to use interferon as a drug therapy, we found side effects like nausea, fatigue,
headache, vomiting, weight loss and fever. We have made progress in altering the molecule to be able to use it as a
drug therapy. We use alpha interferon for genital herpes and hepatitis that involves Hepatitis B and Hepatitis C.
Beta interferon has been found to slow the progression of Multiple Sclerosis.
You should be able to answer Review Questions # 6,7,9,12,15 and Self-Test Questions # 1,5-7 from Chapter 18 in your text.
Specific Immunity, Vaccines (ch 19,21)
The 3rd line of defense is our specific internal defenses or our immune system. We find the immune system to have
two types of immunity: active immunity and passive immunity. Active immunity involves the development of B
and T cells from a naturally occurring infection or in response to a vaccine. Passive immunity involves only our
antibodies. We can take antibodies made by one individual and inject them into another individual who may not
have these antibodies. Another example is a mother that nurses her infant will pass her antibodies to her baby in
the breast milk. The baby is not making these antibodies. In both cases, individuals have these antibodies for
protection for a short time. Watch the difference in protection in active immunity.
The immune system has 3 essential tasks; Recognition of the foreign invader, Activation such that the entire system
prepares to fight the invader and Response where the system acts to either eliminate the invaders or at least
contain the invaders.
We can see that the B cells and T cells will act differently, but together as an entire system, they are quite effective.
B cell immunity (Humoral Immunity):
B cells have antibodies on their surface and move through your body where ever there is fluid (Humors = fluid).
Recognition occurs when the antibody on the surface of the B cell matches the surface receptor (antigen) of the
invading cell.
Activation happens in 2 parts. The B cell will trigger the production of plasma cells. These cells produce the same
antibodies that were on the surface of the B cell and secrete the antibodies as they are produced. The antibodies
can now float through the blood and attach to other antigens. The other part of activation is that the B cell will
trigger the production of “memory” cells. These cells are designed to quickly combat any future identical invaders.
The response of the B cell comes in the form of the antibodies binding to the antigen. The antibody now becomes a
“tag” to have this antigen destroyed.
T cell immunity (Cell Mediated Immunity):
T cell immunity involves your tissue. There are 2 main classes of T cells: T4 (helper cell) and T8 cells. The T4 cell acts
to co-ordinate T cell activity with the B cell activity. They will tell the T8 cell what to do. The T8 cell can become a
suppressor cell or a “killer” cell, depending on the instruction of the T4 cell. The T4 cell contains specific receptors
on its surface that are designed to recognize “self” cells. These cells move through your tissue and when they match
your cells, that is good. When there is no match, it is now Recognition of a foreign cell. (Pay attention to which T
cell is involved in which task)
Activation of the T cells also happens in 2 parts. The T4 will tell the T8 cell to become a “killer” cell and instruct it to
look for the “tagged” cells. The T4 will also trigger the production of “T memory” cells for fighting future identical
invading cells.
Response occurs when the T8 cell actually kills the “tagged” cells. (Where did the tag come from?) See if you can
draw diagrams of these tasks and compare them to each other.
From what we have talked about in this unit, we can appreciate the importance and amazing qualities of our
immune system. We have been able to develop many advances in health care as well as recognizing a few
problems. We’ll look at an example of a problem and then look at some advances. One of the problems with our
immune system occurs when our immune system malfunctions and produces inappropriate or inadequate immune
responses. One of these types of disorders falls under hypersensitivity. Hypersensitivity disorders involve
misdirected immune response where the immune system actually does damage to our own human tissue. We
either have experienced or know someone with an allergy. This is a misdirected immune response that can, at
times, become life threatening. In a systemic allergic reaction, our body releases histamines that cause blood
vessels throughout your body to dilate. These histamines will also cause the constriction of bronchial passageways.
Within 20 minutes, this rapid loss of fluid from your circulatory system can lead to a fall in blood pressure and even
death.
One of the advances in health care comes in our ability to vaccinate individuals to protect them against infectious
pathogens. We also had mentioned earlier in the semester that one of the ways we can identify bacteria is to use
serology. We are actually looking for antibodies (part of our immunity) to identify the microbe. We will look a little
more at this in lab using an agglutination test.
Vaccines (ch21)
Vaccines have come under much debate in recent years and I think it would be good for us to spend a little time
understanding a little more about vaccines: what they are, how they are made, how they work. A vaccine is a
suspension of bacteria or viruses that have been weakened or killed and are used to induce immunity. (Notice this
is just bacteria or viruses. We do not have vaccines for the other microbial groups.) From our understanding of how
the immune system works, we can see how we can trigger active immunity by injecting bacteria or virus into us to
cause our B and T cells to develop and make memory cells. It almost sounds crazy. Why would we actually want to
inject ourselves with a known pathogen? Wouldn’t that make us sick or possibly kill us?
Two Types of Vaccines:
We will only look at 2 types of vaccines to see what they are and how they work. The first one is what is classified
as whole agent vaccines. These can be either inactivated or attenuated. The attenuated vaccine is bacteria or
viruses that have been weakened. It can reproduce; to be in our system long enough for a full response of our
immune system, but will not be able to create the parts that are lethal to us. Inactivated vaccines are ones that the
bacteria or viruses have been killed. When we compare the two types of whole agent vaccines, we can see a
difference in the type of immunity they trigger and what it requires of us. The inactivated vaccine will trigger the B
cells where the attenuated will trigger both B and T cell immunity. The inactivated vaccine requires multiple
boosters where the attenuated vaccine usually requires only one booster. Can you give examples of an attenuated
and inactive vaccine and show their booster requirements? A second type is classified as purified antigen vaccines.
These vaccines are a very specific and purified antigen. It could be a very specific piece of a bacterial cell wall or
viral capsid or even a specific toxin that is produced by a particular pathogen.
We don’t want to leave this subject without at least mentioning some of the risks associated with vaccines. We all
are aware that there can be side effects to any one of the vaccines that are offered. Many people perceive risks to
be greater than the benefits of the vaccine. This has farther reaching dangers for our population as a whole. People
are choosing not to have their children vaccinated because of fear: they hear stories of side effects. What they are
not realizing is that they have no fear of the actual diseases themselves. We will spend the fourth unit on bacterial
diseases. Several of them I have chosen because they are ones that we immunize against and we don’t know (as a
public) what the disease looks like. If the people that are raising opposition to mandatory immunization continue to
sway larger and larger numbers of people in our population it will set the entire population at risk of suffering from
diseases that we need not suffer from. Read about this more in your epidemiology chapter (herd immunity).
You should be able to answer: Review Questions # 12, 13 and Self-Test Questions #8 from Chapter 17 in the text.
Review Questions # 1,7, 8 and Self-Test Questions 6,9,11 from Chapter 19 in the text. Self-Test Questions # 1-5
from Chapter 21 in the text.
Human Defenses Worksheet
1. Inflammation begins when it is _______________ by _____________________. The ___________________ are
triggered to ________________. This causes increased ____________________ to the _______________tissue.
This will cause _____________ and ___________. The capillary now allows _________________ to enter the area.
This will cause ______________and __________________.
2. Phagocytosis begins when it is ________________ by __________________. ___________________ draws the
phagocytes to the infected tissue. The phagocyte then __________________ the pathogen and must use
_______________ to help them _____________ to the pathogen. The phagocyte now _________ the pathogen and
_______________ it. After _________________ the pathogen, the phagocyte will ______________ indigestible
debris.
3. The Complement system functions include _________________________, _____________________ and
______________________________. The system is activated by the _____________________ path or the
____________________ path. The ________________________ requires an _________________________
complex to form on the surface of the pathogen. The ______________________________ requires
______________ molecules to land on the surface of the pathogen. Once activation has occurred,
_______________________ and _________________ will be produced. At the end of the ________________,
multiple __________________ forms a _____________________________________________ on the surface of
the pathogen. This will now _______________________ the pathogen.
4. Interferon is a ___________ molecule that is ___________________ by a cell that has been
___________________ by a __________. The Interferon molecules are _______________ and _____________to
cells that are _______________. These cells will now ____________________ another protein called
_______________________. When new virions are released, they will _____________________ cells with
_______________________ but ________________________.
5. Specific Immunity is _____________________________________________________.
6. B cell tasks:
1. Recognition occurs by _____________ on the ________________ of the _____ cell _________ the
receptor of the _____________ cell.
2. Activation occurs when the _____ cell triggers ________________ of __________cells. These cells in turn
produce and ___________________ the identical ____________________. The ___ cell will also trigger
___________________ of ___________________cells.
3. Response occurs when the _________________________________ the ___________ cell.
7. T cell tasks:
1. Recognition occurs by ________________ on the ______ cell NOT __________ a cell.
2. Activation occurs when the ____ cell triggers the ____ cell to become a ________ cell. The ___ cell will also
trigger ____________________ of ________________ cells.
3. Response occurs when the ______________cell ________ the ___________cell.
8. Vaccines
1. What is a vaccine?
2. Complete the chart
Types of Vaccines
Whole Agent:
Composition of Vaccine
Boosters Required
Type of Immunity
Triggered
Requires multiple
boosters
Whole Agent: attenuated
_______________
Bio 275 Lecture Homework 4
FA19
Instructions:
a. Create an ANSWER SHEET using a Microsoft WORD document.
b. Number your paper and type your answers on that ANSWER SHEET. I do NOT want flow charts. Including
flow charts will result in loss of points!
c. Use complete sentences and your own words.
d. ** #6 and 7** will require you to draw your own diagrams. For these two questions:
a. Draw and label your diagrams.
b. Take a picture of your diagrams. Make sure the picture is clear and easy to read.
c. Paste your picture to your answer sheet. Crop out anything that is not needed so that the answer
sheet is not any longer than it needs to be.
1. Complete the chart. With the TYPES of Defense that are studied in this lecture. (24pts)DO NOT INCLUDE CHART!
2. A. Identify the parts labeled in this diagram. B. What defenses would be working here? (10pts)DO NOT INCLUDE
DIAGRAM
A
D
B
C
3. Complete the flow chart to identify the components of the Complement System (12 pts)
4. Identify the parts of each of these diagrams to show your understanding of the Interferon Defense. (25pts)
Part A. Identify the blue cells, red cell and black object. What has happened in this part of the Interferon
Defense process?
Part B. Identify the blue cells, red cell, black object and purple objects. What has happened in this part of the
Interferon Defense process?
Part C. Identif…
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