Unit 8 quiz

1. Provides an immediate nonspecific immune response

The innate immune system, also known asnon-specific immune system and first line of defense, is a subsystem of the overall immune system that comprises the cells and mechanisms that defend the host from infection by other organisms in a non-specific manner. This means that the cells of the innate system recognize and respond to pathogens in a generic way, but, unlike the adaptive  immune system, it does not create long-lasting or protective immunity to the host.

The innate immune response to infectious and sterile injury is regulated by neural systems that control cytokine production. The Inflammatory Reflex is a prototypical neural system that controls cytokine production in the spleen. Action potentials transmitted through the vagus nerve to spleen regulate the release of acetylcholine, the neurotransmitter that inhibits cytokine release by interacting with alpha7 nicotinic acetylcholine receptors expressed on cytokine-producing cells. This controls the process of inflammation around an injury such as a cut or scratch.

Innate immune system functions include :

gathering cells to infectious areas through the production of chemical factors that include chemical mediators called cytokines.

Activate the compliment cascade to identify pathogens, and promote the clearance of bacteria.
 

2. Activates T and B cells in response to an infection

Leukocytes are produced or stored in many locations in the body, including the thymus, spleen, and bone marrow. For this reason, they're called the lymphoid organs. There are also clumps of lymphoid tissue throughout the body, primarily as lymph nodes, that house the leukocytes. These Leukocytes play an important role in the immune a system, mostly because they are in charge of recognizing and destroying invaders. 

There are two types of Leukocytes:

 phagocytes, cells that chew up invading organisms, and lymphocytes, cells that allow the body to remember and recognize previous invaders and help the body destroy them.

The two kinds of lymphocytes are B lymphocytes and T lymphocytes. Lymphocytes start out in the bone marrow and either stay there and mature into B cells, or they leave for the thymus gland, where they mature into T cells. B cells identify and contain information about foreign invaders, while T cells attack and destroy. 

The histocombatibillity complex (hcm 2) is what delivers the antigen to the B cells and T cells.

When antigens (foreign substances that invade the body) are detected, several types of cells work together to recognize them and respond. These cells trigger the B lymphocytes to produce antibodies, specialized proteins that lock onto specific antigens.

3. Responds to a later exposure to the same infectious agent

Once produced, antibodies continue to exist in a person's body, so that if the same antigen is presented to the immune system again, the antibodies are already there to do their job. So if someone gets sick with a certain disease, like chickenpox, that person typically doesn't get sick from it again. These antibodies also help to quicken the pase of the immune systems response by avoiding the use of phagocytes (cells that "present" pathogens to B cells). 

This is also how immunizations prevent certain diseases. An immunization introduces the body to an antigen in a way that doesn't make someone sick, but does allow the body to produce antibodies that will then protect the person from future attack by the germ or substance that produces that particular disease.

4. Distinguishes self from nonself

T cells compare non-self antigens to HLA (human leukocyte antigens) molecules with proteins the system already knows are its own. Your T-cells don't react to your HLA because of tolerance caused by the memory of the Tand B cells, but are not tolerant to the HLA proteins of someone else. Thus, when there is a non-self system in your body (i.e.: after a transplant or infection), your T-cells will begin a cell-mediated immune response against it, considering them foreign.

Sources:

http://m.kidshealth.org/parent/general/body_basics/immune.html

http://www.nlm.nih.gov/medlineplus/ency/article/000821.htm

http://en.m.wikipedia.org/wiki/File:Innate_immune_system.png

Podcast

https://soundcloud.com/user886627056/transcript/s-JXBFP

Transcript

    Estrogen, in females, is produced primarily by the ovaries, and during pregnancy, the placenta. Estrogen functions mainly to promote the development of female secondary sexual characteristics, such as breasts, and is also involved in the thickening of the endometrium and other aspects of regulating the menstrual cycle. Like most sex hormones, estrogens and androgens, are fat soluble and water repellent. In other words, they "like" lipid or fatty structures such as those surrounding cells but are generally repelled by watery areas. Steroids generally travel to their target cells attached to a special carrier protein that "likes" water .  On the other hand, Most water-soluble hormones, like the amino acid derivatives and peptides, can travel freely in the blood because they "like" water. However, they are repelled by lipid or fatty structures such as the membranes that surround the cell and nucleus. Because of this, these hormones generally bind to receptor sites on the outside of the cell and signal from there.

Follicle-stimulating hormones (FSH) stimulates the ovarian production of estrogens by the granulosa cells of the ovarian follicles and corpora lutea. Some estrogens are also produced in smaller amounts by other tissues such as the liver, adrenal glands, and the breasts. Estrogen is initiated in the simple endocrine pathway,  and synthesizes in theca interna cells in the ovary, by the synthesis of androstenedione from cholesterol. Androstenedione is then converted into androgens such as testosterone as well as estrogen. This compound crosses the basal membrane into the surrounding granulosa cells, where it is converted either immediately into estrone, or into testosterone and then estradiol in an additional step. The conversion of androstenedione and testosterone into estrone and estradiol, is catalyzed by aromatase, enzymes which are expressed in granulosa cells. The actions of estrogen are controlled by the estrogen receptor, a nuclear protein that binds to DNA and controls gene expression. Estrogen enters passively into the cell where it binds to, and activates the estrogen receptor. Since estrogen enters all cells, its actions are dependent on the presence of the Estrogen Receptor in the cell. The Estrogen Receptor  is expressed in specific tissues including the ovary, uterus and breast. Estrogen regulation is also known as a  negative feedback loop, because it inhibits the production of certain hormones. The process starts when the hypothalamus notices a low level of estradiol in the blood and begins releasing a hormone known as gonadotropin releasing hormone (GnRH), which notifies the pituitary gland to make and release both the luteinizing hormone (LH) and the follicle-stimulating hormone (FSH). In females, LH and FSH tell the ovaries to secrete estradiol and progesterone, which stimulates the growth of the egg-producing ovarian follicle and prepares the uterus for pregnancy. In males, LH and FSH notify the testes to secrete testosterone, which stimulates sperm production. The ovaries make and release estradiol until a certain level is reached in the bloodstream. The hypothalamus and pituitary notice the increase and stop secreting GnRH, LH and FSH hormones. This causes the ovaries to stop releasing estradiol and progesterone until the level in the blood decreases to a low enough level that then reactivates the process.

Citations

"E.Endocrine System : Types of Hormones." E.hormone. Tulane University, 2014. Web. 03 Mar. 2014.

"Endocrine System : Feedback Loops." E.hormone. Tulane University, 2014. Web. 03 Mar. 2014.

"Estrogen." Wikipedia. Wikimedia Foundation, 20 Feb. 2014. Web. 01 Mar. 2014