Textbook Notes (362,842)
Canada (158,078)
HLTB21H3 (177)
Chapter 5

Chapter 5.docx

3 Pages
Unlock Document

University of Toronto Scarborough
Health Studies
Rhan- Ju Song

Chapter 5: A Modern Plague, AIDS  AIDS is a deadly disease for which there is no cure or vaccine  It is the first pandemic of the 21 century A Look Back  AIDS- the virus called the human immunodefiency  Kaposi’s sarcoma: red-purple blotching on the skin  GRID- gay related immune deficiency  The virus was renamed human immunodefiency virus (HIV), and the complex disease it produced was called acquired immunodefiency disease syndrome (AIDS)  HIV is a virus- an entity that one biologist defined as a “bit of bad news wrapped in protein”, o A virus is spherical in shape, resembling a 20-sided soccer ball. With a diameter of only 1,00 Angstrom o Viruses are not cells, but they are able to reproduce themselves by taking over the machinery of a living cell, they are the ultimate parasite HIV discovered  The discovery of HIV began more than a century ago  Replication of RNA viruses involves the transfer of information from the viral DNA copy, and that the viral DNA was integrated into the chromosomes of the transformed cancer cells HIV’s Target: the Immune System  Blood consists of cells suspended in a yellowish, salt and protein containing fluid called plasma  There are two kinds of cells in our blood: red blood cells and white blood cells o The red blood cells contain hemoglobin ( responsible for the red colour of blood) and are involved in the transport of oxygen to and removal of carbon dioxide from the tissues o The white blood cells are a part of the body’s defence system and play a key role in immunity  Three kinds of white cells: eosinophil’s, basophils, and neutrophils o And there are two kinds that lack granules in the cytoplasm, called lymphocytes and monocytes  The lymphocytes and macrophages are produced in the bone marrow but are found in regional centres such as the spleen and the lymph nodes as well as in the blood  Lymphocytes are divided into two different types, called T and B. o The B lymphocytes make antibody either one their own or by being activated by a T-helper cell, called T4. The T4 lymphocytes are so named because they have on their surface a receptor molecule, CD4. Macrophages also have CD4 on their surface. o Another kind of T lymphocyte, called a killer cell, is also activated by the T4 helper cell. T cells, unlike B cells, do not make antibody, but they are involved in what is referred to as cell-mediated immunity o Cell mediated immunity is the immunity that is responsible for transplant rejection and for delayed hypersensitivity reactions such as those that occur after being stung by a bee o Although T cells do not make antibody, they can communicate with one another using soluble chemicals called chemokine’s. Chemokine are soluble chemical messengers that attract or activate other white cells, especially T and B lymphocytes and macrophages o To be activated, these white cells must have on their surface a receptor for the chemokine. One chemokine receptor, called alpha, is an entry cofactor for the invasion of T cells by HIV, and it also activates neutrophils o Another chemokine receptor, called beta, is an entry factor for the invasion of macrophages by HIV, and it activates monocytes, lymphocytes, basophils, and eosinophil’s  The glycoproteins of the HIV capsid resemble a lollipop. The “stick” is called gp41, and the “candy ball” is gp120 o The functions of these two viral proteins are to bind and anchor the HIV to the surface of the cell o CD4 on the surface of the T cell allows for the docking of gp120, once docked, the gp120 changes its shape so that it can bind to the chemokine receptor, and after binding there is fusion and entry of HIV 1 HIV and AIDS  Approximately 90% of people infected with HIV die within 15 years if untreated o It is the quantity of the virus carried in the blood that determines how quickly death will occur o The more virus particles, the more likely AIDS will develop  The reason for this is that the more HIV there is in the blood the faster there will be destruction of the immune system and the quicker will be the development of infections  One of the characteristics of an HIV infection is depletion of T4 cells o In an healthy individual there is around 1000 T4 cells o When the count reaches 400-800, the first opportunistic infections appear. They are ones that under ordinary circumstances cause no disease; however, in individuals with a weakened immune system, some parasites are able to take the opportunity afforded them by the body’s crippled defenses, and the result is clinical disease  The first opportunistic diseases are annoying infections of the skin and mucous membranes, such as thrush (painful sores that usually occur in the mouth) and shingles (an infection of the
More Less

Related notes for HLTB21H3

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.