Defense Against Infectious Diseases

This blog post is going to be a little different from the ones I've made before. After all, the blog is for my personal use and I want to make it more engaging for me. Therefore this post will be more concise, and I will use bullet points answering the IB Assessment Statements to do so.

1.Pathogens-Any living organism or virus that is capable of causing a disease. They include viruses, bacteria, protozoa, fungi, and worms of various types.

2.Antibiotics-Chemicals that take advantage of the differences between prokaryotic and eukariotic cells.

• many types: some selectively block protein synthase while others inhibit the production of new cells
• antibiotics damage or kill PROKARYOTIC cells, but not eukaryotic cells and their metabolism

*Viruses use our own cells' metabolism to creat

e new viruses. Thus, they "hide" in our own cells using them as host cells, and that's why antibiotics don't work against viruses.

3. *Skin: Barrier to infection

• dermis:contains sweat glands, capillaries, sensory receptors, and dermal cells. They give structure and strength to skin.
• epidermis:(dead cells) not truly alive and they are intact= protected from most pathogens

*Mucus:(trachea, nasal passages, urethra, vagina)

• cells produce and secrete lining of mucus
• trap incoming pathogens
• some lined with CILIA-hair like extensions
• lysosyme-enzyme that damage pathogens

4.Phagocytic Leukocytes (WBC)

• Macrophages-large WBC that are able to change their cellular shape to surround an invader and take it in through the process of PHYGOCYTOSIS
• engulf pathogen- just like lysosomes in cell
  
  

5. Antigens vs Antibodies

• antigens-molecules that our immune system considers to be "not-safe"
• antibodies-protein molecules that we produce in response to specific types of pathogens

6.Antibody production

• specific immune response
• pathogen enters body
• macrophage engulf pathogens
• pieces of pathogen become part of macrophage's membrane
• antigen presentation=lymphocytes T recognize pieces=are activated
• T cells activate specific B cells-they divide (by cloning) and form:

-plasma cells=secrete antibodies that bind to antigens

-memory cells-stay in circulation

7.Effects of HIV on immune system

• HIV (human immunodeficiency virus)-results in the set of symptoms called AIDS
• reverse transcriptase (enzyme) enables genetic info. of HIV to become integrated permanently into genome of host cell
• infects helper T cells- disables them=no antibody production=body doesn't fight pathogens as it used to before

8. AIDS

• caused by HIV
• transmition: person to person by body fluids (blood transfusions/ sex/ etc)
• social implications: discrimination against infected people=labeled as homosexuals/drug abusers/ hard time finding jobs/ etc.
• its a virus=immune to vaccine (hides away in host cells)

Transport System

The transport system refers to the transport of blood around the body. The blood can be transported by circulation, which is divided in three groups: Coronary Circulation, Systematic Circulation, and Pulmonary Circulation. Coronary Circulation is the one people give more emphasis to because it describes how the blood is pumped to the rest of the body by the heart. The heart as we might know is a myogenic muscle, which means it's a muscle that contracts. So, what happens is that the blood from the body enters the vena cava and goes to the right atrium. Once the blood fills up the atrium, a valve called the atrio-ventricular valve opens and lets the blood flow to the right ventricle. Then, after there is no more space for blood in the ventricle, another valve called the semi-lunar valve opens and lets the blood flow through the pulmonary artery, which is an artery that will lead the blood to pass through the lungs. After going through the lungs, the blood will enter the heart again through the pulmonary veins. Then, it will go through the left atrium, the left atrio-ventricular valve, through the left ventricle, and then through the left semi-lunar valve. Finally, the blood will again go to the rest of the body exiting through the aorta.

Every time blood travels through the heart, it creates a heartbeat. The heartbeat can be influenced by chemicals, such as adrenaline. When you are exercising and there is little oxygen and a lot of CO2 in your body, the medulla (part of brain) sends a signal to the SA Node, or the peacemaker to increase heartbeat so that blood with oxygen can travel to your lungs faster. The SA Node then sends a signal to the AV Node and it results in the contraction of the muscle.

So, we have the transport of the blood through our body, and we have a heartbeat. But why is it important to have blood in our body? Well, first of all, the blood carries the oxygen and nutrients necessary for our body. Blood is made out of plasma, which is a fluid that contains water, hormones, and CO2. There are two different types of blood cells: white blood cells and red blood cells. The white blood cells are for body defense, which is why they contain platelets and antibodies. The red blood cells, on the other hand, contain hemoglobin. Hemoglobin is rich in iron, which not only gives the red color to the blood but also helps to carry oxygen through the body.

Finally, we should be able to understand how blood vessels help to carry the blood in all of the processes mentioned above. The most important vessels are arteries, veins, and capillaries. Arteries have a thick muscle layer to ensure high blood pressure and they transport mainly oxygen. Veins have thin flexible walls to ensure low blood pressure and they carry mainly CO2. Valves are also a type of vein which prevent the back flow of blood. We saw two examples of valves in the heart: the atrio-ventricular and the semi-lunar valves. And lastly, the capillaries have a one-cell-thick wall and their job is to connect veins and arteries.