IMMUNE SYSTEM, HIV & CANCER Flashcards
immune system is compoesed of…
various organs, cells, enzymes, and hormones that provide protection against infection-causing microorganisms.
concomitant disease
A concomitant disease is a second illness occurring at the same time as a primary illness
Innate immunity
the general and nonspecific immunity that your body possesses to fight various diseases.
It comprises defense barriers such as the skin, hair, sebum, saliva, neutrophils, monocytes, and other enzymes that immediately detect and destroy the pathogens.
It’s a rapid response system that acts as the first line of defense against infections.
You are born with the components of innate immunity, and it can’t be learned, created, or produced- hence the name “innate”.
Since bacteria and viruses multiply quickly, innate immunity is crucial in providing protection until the second line of defense, or adaptive immunity, starts involving in the process.
In addition to providing the first line of defense against disease-causing microorganisms, the innate immune system activates, directs, and instructs components of the adaptive immunity.
It also regulates inflammation and maintains equilibrium among various immune system processes.
Adaptive immunity (acquired immunity)
comes into play when innate immunity is breached.
Adaptive immunity isn’t very helpful in protecting your body when a specific bacteria, virus, or any other microorganism enters your body for the first time.
Its components function by learning the pathogen and then developing immunity against it.
Adaptive immune responses are continually refined and adjusted throughout your lifetime.
Antigen
Foreign substance recofnized by your body in the form of an outsider protein.
An antigen triggers the production of antibodies, which attack the antigen to destroy it. A specific type of white blood cell (WBC) called the lymphocyte is a major cell of the adaptive immune system.
Lymphocytes are further classified as?
T lymphocytes (T cells)
B lymphocytes (B cells)
Vaccines
Are manufactured based on the adaptive immune system function. An antigen derived from a particular disease-causing bacteria or virus is manufactured, then introduced into the body in the form of a vaccine.
Vaccines are administered to healthy individuals to trigger the adaptive immune response and produce antibodies against that antigen without causing the disease.
Three types of granulocytes
neutrophils
eosinophils
basophils
Neutrophils
Are the most prevalent types of WBCs.
They respond to bacterial infections, such as pneumonia or urinary infections, by engulfing the bacteria through the process of phagocytosis and are often referred to as phagocytes.
If the infection is moderate to severe, the bone marrow will produce extra neutrophils. Neutrophils are observed during the early stages of acute inflammation.
Eosinophils
Are predominantly involved in allergic reactions.
Their concentration may be elevated after allergic reactions to food or drugs.
Eosinophils also help fight parasitic infections.
Basophils
Like the other granulocytes, are involved in the process of inflammation.
They’re the rarest of leucocytes.
Basophils help combat allergic reactions by releasing two chemicals:
Histamine
Heparin
Agranulocytes
Produced by the bone marrow.
Don’t contain secretory granules in their cytoplasm.
Two types of agranulocytes: Lymphocytes & Monocytes
They’re part of innate immunity and are the important first responders to infection.
The bloodstream helps by continuously circulating immune cells throughout the body.
B cells produce….
antibodies
T cells …..
participate in cell-mediated immune response against bacterial and viral infections.
T cells don’t produce antibodies. They simply attack atypical or abnormal cells, causing death of the diseased cell by activating macrophages or by inducing a series of chemical reactions that encourage the cell to die (apoptosis).
Main function monocytes
Like neutrophils, To engulf and digest the damaged cells and pathogens.
Monocytes function as part of innate immunity.
Antibodies, or immunoglobulins function:
Specifically bind with pathogens to deactivate them or tag them to be destroyed by specific WBCs. Producing antibodies against a known antigen is your body’s way of providing future protection from infection by the same pathogen.
Cytokines
Proteins produced by various cells, including the immune cells. Cytokines play an important role in the immune system by sending and receiving signals to carry out various immune system processes.
Cytokines communicate with immune cells to help regulate, direct, and amplify the immune response.
thymus
a small endocrine gland located in the upper chest area.
The main function of the thymus gland is to develop a newborn’s immune response; in adults, the thymus continues to be important in the maturation of lymphocytes, specifically T lymphocytes.
While the bone marrow is responsible for the production of lymphocytes from stem cells, only B cells mature there.
T cells, on the other hand, mature in the thymus.
First, the bone marrow sends some immature lymphocytes out to the blood to be deposited in the thymus gland.
Here, the immature lymphocytes become thymocytes and further mature to become T lymphocytes or the T cells.
The thymus gland is considered a part of the lymphatic system.
apoptosis
T cells don’t produce antibodies. They simply attack atypical or abnormal cells, causing death of the diseased cell by activating macrophages or by inducing a series of chemical reactions that encourage the cell to die (a process known as apoptosis).
lymphatic system
Is a network of vessels and tissues that carry lymph throughout your body.
This system is also composed of the thymus gland and lymph nodes.
Similar to blood, lymph is an extracellular fluid that continuously circulates throughout your body. Immune cells are carried through the lymphatic system and stored in the lymph nodes, which are found throughout your body.
This network transports excess fluid from the tissues back to the circulatory system, filters bacteria, acts as an emergency reservoir of blood, destroys and removes old red blood cells, and produces monocytes and T lymphocytes for the immune system. The lymphatic system also absorbs fats from the small intestine and delivers them into the bloodstream. Lymph nodes serve as spots where stored immune cells may detect a foreign pathogen and initiate the immune response against the pathogen. Thus, swollen lymph nodes are usually indicative of your body’s active immune system.
lymph
is an extracellular fluid that continuously circulates throughout your body.
Immune cells are carried through the lymphatic system and stored in the…….?
lymph nodes
Location of the spleen
on the left side of the abdomen, just below the diaphragm.
Spleen function
The spleen also stores immune cells and activates these cells to respond to disease-causing pathogens.
It stores lymphocytes and other blood cells, and it filters out bacteria and viruses from the arterial blood circulation.
As the blood passes through the capillary network in the spleen, it comes into contacts with lymphocytes that clear the blood of any infected cells that may be there.
T cells, as you’ve learned, work to destroy atypical, infected, or defective cells.
B cells produce antibodies that will work to destroy future infections when they’re recognized again.
In a fetus, one of the main functions of the spleen is to produce lymphocytes and red blood cells.
Before the long bones are fully formed and able to produce cells, the spleen is where the blood cell formation occurs.
Once the bones take over production, the spleen focuses on storing and filtering blood and fighting infection.
Examples of autoimmune diseases :
- Myasthenia gravis (MG)
- Rheumatoid arthritis (RA)
- Insulin-dependent diabetes mellitus (IDDM)
- Multiple Sclerosis (MS)
- Lupus (SLE)
HIV
is a virus that causes AIDS, a disease that suppresses the body’s natural immune system. The virus destroys the T lymphocytes (T cells) that fight infections, leaving patients prone to deadly infections. In some cases, the immune system is suppressed using medications to protect against autoimmune diseases and certain cancers. It’s also sometimes done to prevent organ rejection after an organ transplant.
How can HIV be transmitted?
blood transfusions
intravenous drug use
male-to-female sexual contact female-to-female sexual contact mother to baby
exposure in the workplace from patient to healthcare worker
HIV is most commonly found in….
Blood
Semen
Vaginal Secretions
mid-stage period of HIV infection
Is persistent generalized lymphadenopathy, in which enlarged lymph nodes, skin rashes, chronic fatigue, and weight loss occur. Finally, full-blown AIDS strikes, rendering the immune system powerless. The patient becomes subject to opportunistic infections such as Kaposi’s sarcoma (KS), Pneumocytis carinii pneumonia (PCP), and lymphoma.
Persistent generalized lymphadenopathy
Persistent generalized lymphadenopathy (PGL) is enlarged, painless, non-tender lymph nodes occurring in a couple of different areas for more than three to six months for which no other reason can be found.
Kaposi’s sarcoma
Kaposi’s sarcoma (KS) is a type of cancer that can form masses on the skin, in lymph nodes, in the mouth, or in other organs.[4][6] The skin lesions are usually painless, purple and may be flat or raised.[6][8] Lesions can occur singly, multiply in a limited area, or may be widespread.[6] Depending on the sub-type of disease and level of immune suppression, KS may worsen either gradually or quickly
Pneumocytis carinii pneumonia
Pneumocystis pneumonia (PCP), also known as Pneumocystis jirovecii pneumonia (PJP), is a form of pneumonia that is caused by the yeast-like fungus Pneumocystis jirovecii.
The HIV life cycle
- Binding- HIV binds to the CD4 cell surface.
- Fusion- HIV and CD4 cell membrane fuse.
- Reverse Transcription- HIV, using its enzyme reverse transcriptase, converts its RNA into DNA. DNA then enters the CD4 cell nucleus.
- Integration- Another HIV enzyme, integrase, facilitates the insertion of the HIV DNA into the CD4 cell DNA.
- Replication- Now as part of the CD4 DNA, HIV begins to replicate its own RNA and other HIV proteins.
- Assembly- New HIV RNA, along with other viral proteins, produces an immature HIV.
- Budding- Immature HIV comes out of the CD4 cell and uses its own enzyme called protease to become a mature and infectious HIV.
PJP
Is a type of lung infection, or pneumonia, caused by a microorganism called Pneumocystis jirovecii. It’s the most common and life-threatening infection in HIV-infected patients. PCP prophylaxis with the following medications is recommended for patients with HIV infection:
Sulfamethoxazole/Trimethoprim (Bactrim)
Dapsone (Dapsone)
Atovaquone (Mepron)
Pentamidine inhalation (Nebupent)
MAC
MAC is a group of bacteria that can cause serious and deadly infections of the lungs, bones, and blood in HIV patients. MAC infection is generally considered an end-stage complication of AIDS. MAC prophylaxis with the following medications is recommended for patients with HIV infection:
Azithromycin (Zithromax)
Clarithromycin (Biaxin)
Rifabutin (Mycobutin)
The three types of organ rejection:
Hyperacute
Acute
Chronic
Hyperacute rejection
Cccurs within minutes of implanting a new organ. One of the main causes of this type of rejections is mismatched blood type or other markers. Hyperacute rejection usually requires removal of the new organ.
Acute rejection
Occurs within two or three weeks of the organ transplant. It’s a T-cell mediated immune response to specific markers on the donor organ.
Chronic rejection
Usually occurs after three or more months of the organ transplant. It’s a B-cell mediated response that produces antibodies against the donor organ.
Immunosuppression
Is a phenomenon of decreased or total lack of immune response in the body.
It may be caused by diseases such as cancer and HIV infection. Immunosuppression may also be induced during an organ transplant and then be continued as maintenance therapy to prevent chronic rejection.
Patients on immunosuppressive medications after an organ transplant are at higher risk of contracting infections.
Patients are generally instructed to practice good hand hygiene, avoid close contact with the sick, and stay away from crowded places.
Induction immunosuppressive therapy
To prevent acute organ rejection, induction immunosuppressive therapy is administered before, during, or immediately after the organ transplant.
Induction therapy works by depleting functional lymphocytes to prevent an immediate immune response against the new organ.
The following medications are commonly used as induction therapy to eliminate all antibodies against the new organ:
Antithymocyte globulin (Atgam or ATG, and rATG)
Muromonab-CD3 (OKT3)
Anti-interleukin-2 (IL-2)
Basiliximab (Simulect)
The following medications are commonly used to avoid chronic rejection:
Cyclosporine (Sandimmune, Neoral)
Tacrolimus (Prograf)
Methylprednisolone (Solu-Medrol)
Prednisone (Prelone)
Azathioprine (Imuran)
Mycophenolate (CellCept)
METASTASIS
When cancer cells break away from the initial, or primary, site of the disease, a secondary metastatic growth can develop in another part of the body.
If cancer proceeds to grow exponentially, it will start invading the tissues of the surrounding area. Further progression starts attracting the lymph system to pick up damaged cells from the cancerous site to bring them to the lymph nodes to destroy. Since cancerous cells multiply rapidly, the lymph nodes often become overwhelmed and inflamed by the number of abnormal cells collected in them.
For this reason, lymph nodes are routinely checked when cancer is suspected. When the lymph system becomes overwhelmed, it’s unable to get rid of all the abnormal cancer cells.
Abnormal cells will move along with the lymph until they’re deposited again into the venous system. The lymph becomes plasma and moves along the bloodstream, where it’s deposited into tissues as interstitial fluid. This process, called metastasis, allows cancer to spread easily to various locations.
Metastasis Example
If a cancer has metastasized to another area of the body, the patient isn’t considered to have two different kinds of cancers. Consider this example:
The cells in the breast are different from lung cells. If a patient has a primary breast cancer tumor and, during treatment, another tumor is discovered in a lung, the pathologist can identify the cancer from the cell type. There are two possibilities. If the tumor is found to have cells of the type that are found in the breast, then this is metastatic breast cancer, or breast cancer that has traveled through the lymph system and continued to produce malignant cells within the lung. However, if the pathologist finds that the tumor is composed of cells that are consistent with other cells in the lung, but abnormal, then the patient would be considered to have primary lung cancer as well as primary breast cancer and this would not be a case of metastasis.
In cases of advanced cancer, the cells may be so undifferentiated that it’s difficult to tell where they came from. Thus, there are several systems of grading and staging tumors that can help to pinpoint the degree of disease from which the patient is suffering.
neoplasms
Cells in your body are constantly growing and dividing. Sometimes, cells begin to multiply in an uncontrolled fashion and develop an abnormal tissue or growth. The abnormal cells or growth have no useful physiological purpose in the body and can cause irreparable damage. These abnormal growths are called neoplasms.
The study of neoplasms
Oncology
Two types of neoplasms
Benign
Malignant
Both types of neoplasm can cause a lump to form in the tissue, called a
Tumor
benign neoplasm also called
benign tumor
A malignant neoplasm is called
Cancer
The following characteristics differentiate benign tumors from cancerous tumors:
Benign tumors grow slowly; cancer grows rapidly
Benign tumors are often enclosed by a well-defined membrane border; cancerous tumors are non-capsulated, with an ill-defined membrane border, and project into surrounding tissues
Benign tumors don’t usually cause harm to the body unless they’re large and interfere with the proper functioning of surrounding tissue. For example, due to the limited space in the cranium, benign brain tumors may be harmful to the surrounding brain tissue. Malignant neoplasms or cancer cells are always dangerous, no matter where they are, since the cells will travel through the blood and lymph to invade tissues near and far.
Benign neoplasms don’t usually grow back after surgical removal; cancer cells frequently regenerate after surgical removal.
carcinogenesis
Process of normal cells transforming into cancerous cells.
Researchers believe this process occurs in the genetic code of the cells, the deoxyribonucleic acid (DNA) of chromosomes. In normal cell division, a group of genes called proto-oncogenes handle the proteins necessary for that division. In normal DNA, DNA repair genes and tumor suppressor genes can reverse damage in the cells.
In normal cell division, a group of genes called ……..handle the proteins necessary for that division.
proto-oncogenes
……..can reverse damage in the cells
DNA repair genes and tumor suppressor genes
DNA repair genes function
correct any abnormalities in cells before they divide.
tumor suppressor genes function
control the growth rate of cells, instructing them to kill themselves (apoptosis) if they start multiplying too rapidly or if the DNA repair genes can’t fix the defect.
oncogenes
proto oncogenes mutated
Mitosis
Cell division
Once the genetic material of a cell has transformed, or mutated the genetic code is……
lost
How can cancer be passed down?
A change in DNA structure can be passed down to subsequent generations through the transfer of DNA from parents to a fetus.
Some cancers result from a defect in the arrangement of DNA chromosomes in the original egg and sperm that created the individual.
A child can be born with a defect in the chromosomes that will cause mutation if activated.
The factors that activate a gene are unclear.
Some cancers have biological causes, relating to factors such as aging and reproductive history. These changes happen during a person’s lifetime.
They’re called acquired, or somatic, mutations.
Carcinogens Household chemicals:
Benzene in glues, insecticides, tobacco smoke, and additives in processed foods.
Carcinogens Industrial pollutants:
Arsenic from mining and smelting, asbestos from construction, benzene from oil refineries.
Carcinogens Radiation:
Ultraviolet rays from the sun, X-rays and radioactive substances from diagnostic and therapeutic procedures.
Carcinogens Hormones:
Primarily the synthetic estrogen diethylstilbestrol (DES)
Carcinogens Viruses:
Hepatitis B virus can lead to liver cancer and human papillomavirus is known to cause cervical cancer.
The American Cancer Society recommends regular physical exams and has publicized the acronym CAUTION, which states the following seven early signs of cancer:
Change in bowel habit
A sore that doesn’t heal
Unusual bleeding or discharge
Thickening of tissue or a lump
Indigestion or trouble swallowing
Obvious changes to moles or warts
Nagging cough or persistent hoarseness
Classifications containing the suffix -oma, which means “tumor”, connected to a body part word, are almost always ……
Benign
Examples include papilloma (an epithelial tumor), adenoma (a tumor originating in a gland), or osteoma (a bony tumor usually found on the skull).
But the combining forms carcin(o) and sarc(o) turn the suffix- oma into
a serious illness
papilloma
an epithelial tumor
