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By the end of this section, you will be able to:
  • Explain the development of immunological competence
  • Describe the mucosal immune response
  • Discuss immune responses against bacterial, viral, fungal, and animal pathogens
  • Describe different ways pathogens evade immune responses

Now that you understand the development of mature, naïve B cells and T cells, and some of their major functions, how do all of these various cells, proteins, and cytokines come together to actually resolve an infection? Ideally, the immune response will rid the body of a pathogen entirely. The adaptive immune response, with its rapid clonal expansion, is well suited to this purpose. Think of a primary infection as a race between the pathogen and the immune system. The pathogen bypasses barrier defenses and starts multiplying in the host’s body. During the first 4 to 5 days, the innate immune response will partially control, but not stop, pathogen growth. As the adaptive immune response gears up, however, it will begin to clear the pathogen from the body, while at the same time becoming stronger and stronger. When following antibody responses in patients with a particular disease such as a virus, this clearance is referred to as seroconversion (sero- = “serum”). Seroconversion is the reciprocal relationship between virus levels in the blood and antibody levels. As the antibody levels rise, the virus levels decline, and this is a sign that the immune response is being at least partially effective (partially, because in many diseases, seroconversion does not necessarily mean a patient is getting well).

An excellent example of this is seroconversion during HIV disease ( [link] ). Notice that antibodies are made early in this disease, and the increase in anti-HIV antibodies correlates with a decrease in detectable virus in the blood. Although these antibodies are an important marker for diagnosing the disease, they are not sufficient to completely clear the virus. Several years later, the vast majority of these individuals, if untreated, will lose their entire adaptive immune response, including the ability to make antibodies, during the final stages of AIDS.

Hiv disease progression

This graph shows the concentration of HIV viral particles in blood over time in years.
Seroconversion, the rise of anti-HIV antibody levels and the concomitant decline in measurable virus levels, happens during the first several months of HIV disease. Unfortunately, this antibody response is ineffective at controlling the disease, as seen by the progression of the disease towards AIDS, in which all adaptive immune responses are compromised.

Everyday connection

Disinfectants: fighting the good fight?

“Wash your hands!” Parents have been telling their children this for generations. Dirty hands can spread disease. But is it possible to get rid of enough pathogens that children will never get sick? Are children who avoid exposure to pathogens better off? The answers to both these questions appears to be no.

Antibacterial wipes, soaps, gels, and even toys with antibacterial substances embedded in their plastic are ubiquitous in our society. Still, these products do not rid the skin and gastrointestinal tract of bacteria, and it would be harmful to our health if they did. We need these nonpathogenic bacteria on and within our bodies to keep the pathogenic ones from growing. The urge to keep children perfectly clean is thus probably misguided. Children will get sick anyway, and the later benefits of immunological memory far outweigh the minor discomforts of most childhood diseases. In fact, getting diseases such as chickenpox or measles later in life is much harder on the adult and are associated with symptoms significantly worse than those seen in the childhood illnesses. Of course, vaccinations help children avoid some illnesses, but there are so many pathogens, we will never be immune to them all.

Could over-cleanliness be the reason that allergies are increasing in more developed countries? Some scientists think so. Allergies are based on an IgE antibody response. Many scientists think the system evolved to help the body rid itself of worm parasites. The hygiene theory is the idea that the immune system is geared to respond to antigens, and if pathogens are not present, it will respond instead to inappropriate antigens such as allergens and self-antigens. This is one explanation for the rising incidence of allergies in developed countries, where the response to nonpathogens like pollen, shrimp, and cat dander cause allergic responses while not serving any protective function.

Questions & Answers

ഫസ്റ്റ് ചാപ്റ്റർ ഇംപോർട്ടൻസ് പോസ്റ്റ്
Reshma Reply
Yes....
Loving
nhi samjh aya
Anshika
Nhi wt is this
Loving
I don't know
Anshika
Okk wre frm u r
Loving
what is mean of? reshma
Asad
D bone in d ankle joint re what ?
Ifunanya Reply
can one define a cell as a basic unit of a living organism
Michael Reply
Which of the following hormones are responsible for the adolescent growth spurt? estrogen and testosterone, even in women?
Kepa Reply
estrogen
Farhana
Estrogen!
Jazil
estrogen hormone
Michael
yes estrogen hormone
Anshika
yes
Sale
What is sling give d characteristics of sling uses of sling
adamu Reply
a sling a rope used in hunting ie throwing of rocks
Michael
I went to learn anatomy of joints
Arman Reply
me 2
adamu
joint have 3 cartilaginous joint fibrous joint synovial joint U can reserch in Google can explain U well
sopheaktra
define sling
adamu
To throw with a circular or arcing motion
real
what is respiration
Osele Reply
what is respiration
Paul
Respiration is the process by which oxygen is taken in and carbon dioxide is given out.
Md
Respiration is the combination of inhalation and exhalation.
Khim
inhalation is the taking in air from environment to lung and exhalation is taking out sir from the lung to environment ..
Khim
is the process by wich gases(oxygen and carbon(IV)oxide go through the nose, trachea and the lungs to the blood stream
Michael
what is holistic
Kibrom Reply
Holistic means encompassing the whole of a thing, and not just the part. Holistic medicine looks at the whole person for answers, not just at physical symptoms. You might have heard of holistic medicine, which tries to treat someone as mind and body, instead of treating only the part of the patient
I want to learn one by one system like skeleton system... muscular system
Mary Reply
i want to learn this
Kibrom
what is the difference between regional anatomy and system anatomy
David
system anatomy is when we study the system like digestive, circulatory, reproductive, but regional anatomy is studying the anatomy by regions of body like anatomy of neck, thorax, head etc. Regional anatomy may include system anatomy...
Biplav
yes
Anshika
explain in details factors that affects bone development
Precious Reply
describe the process of bone healing
Precious
out line factors that delays bone healing
Precious
actually,for the bone formation they must be sufficient level of calcium,phosphorus and vitamin D in the body for it to happen smoothly.
lucky
the above mentioned substances are the ones able for the formation and repairing of bones.
lucky
explain in details factors that affects bone development
Precious
what are tissue
muki Reply
a lots of cells make tissue and a cell body is tissue
Rabab
cells come together to form a tissue and tissues come together to form an organ
Adoma
what is appendicular skeleton
OSE Reply
appendicular skeleton is upper limbs and lower limbs
sopheaktra
what is decompression sickness?
Japhar Reply
It occurs in Scuba divers when they rise too quicky to the sea surface , their oxygen tanks have oxygen mixed with N2 gas which has a high solubility at sea level , when the diver rises the N2 gas bubbles out of plasma and this causes Air Ebolism
Siphiwesihle
if a single part if Nervous system doesn't function like synapse? what will occur
Lilian Reply
no transmission of impulses no respond cause mechanical damage
Komolika
what happens when calcium ion channel is blocked
Jachike
a MORAH /MORAH
Kechi
meaning?
Jachike
transmission of impure
sopheaktra
when calcium ion channels block . lightheadedness Low blood pressure. Slower heart rate. Drowsiness. Constipation. Swelling of feet ankles and legs. Increased appetite. Gastroesophageal reflux disease (GERD
sopheaktra
I'm not sure about it
sopheaktra
low blood pressure
Anshika
what is this substance
Peng Reply
In the human body, there are no atoms as separate entities. Instead, they constantly interact with other atoms to form and break down more complex materials. To fully understand anatomy and physiology, you must understand how atoms are involved in such interactions. The key is to understand the beha
Warid
what are functions of muscle cell
Veronicah
please can someone help with ten functions of the following hormones 1.Gastrin 2. Adrenal sex hormone 3. Secretin 4. Follicle Stimulating Hormone 5. Glucagon 6. Progesterone
Har
4.produces the oetrogen and bursts open to release egg cells.
Komolika
5.regulates the level of glucose in the blood and it is secreted when glucose low in the blood.
Komolika

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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