HIV/AIDS Diagnosis

upstream causes

downstream effects

Physiology

Anatomy

Indirect cause

Direct cause

Infected by human Immunodeficiency virus (HIV)

blood transfusion, blood-contaminated needles, sexual intercourse/oral sex, or from mother to fetus

Viral VS bacterial infection

organs and cells of immune system

Secondary Lymphoid organs: nodes, spleen, MALT, and diffuse lymphoid tissues

Primary lymphoid organs: bone marrow and thymus; (T and B cells originate in bone marrow)

B cells mature in bone marrow; create antibodies; present antigens to helper T cell to assist their own activation

T cells mature in Thymus

(areas where mature lymphocytes encounter their fist antigen and become activated)

Natural Killer (NK) cells: non-phagocytic; can kill cancer and virus-infected cells before adaptive immune system activated; kill by inducing apoptosis

dendritic cells: phagocyte; APC to t-cells in lymph nodes

macrophages: APC to t-cells which activates them and further activates macrophages

CD4 cells: become helper T cells that activate B cells, other t-cells, and macrophages and direct the adaptive immune response

CD8 cells: become cytotoxic t-cells that are capable of destroying and harboring foreign antigens

Innate and Adaptive immune systems

Innate (non-specific, quick reaction time)

Adaptive (specific defense; takes longer to react)

first line of defence

second line of defense

external body membranes (skin, tears, sweat, saliva, mucus, cilia, stomach acid..)

antimicrobial proteins, phagocytes, and other cells (inhibit spread of invaders; inflammation most important mechanism)


stop attacks by pathogens; Many second-line cells have pattern recognition receptors that recognize (bind to) structures on microbes and then sound a chemical “alarm” that initiates inflammation

stop attacks by pathogens

specific: recognizes and targets specific antigens

systemic: not restricted to the initial site

involves lymphocytes (B and T cells)

memory: mounts stronger attack to "known" antigens

2 branches

Humoral Immunity: has extracellular targets (antibodies in blood bind temporarily to target cell to inactivate it)

cellular immunity: has cellular targets (lymphocytes act against target cell)

Function of specific leukocytes (lymphocytes already mentioned)

monocytes: macrophages; fight chronic infections; phagocytize dead cells and debris also

lymphocytes

neutrophil: enter tissue spaces and phagocitize infectious pathogens

eosinophils: target parasitic worms and play a role in allergies

T cells: act against virus infected cells and tumor cells

B lymphocytes: give rise to plasma cells, which produce antibodies

basophils: granules contain histamine (inflammatory chemical that acts as vasodilator and attracts other WBC's to inflamed site)

viral infection: caused by a virus

bacterial infection: caused by bacteria

can be caused by a secondary infection (virus started initial infection)

do NOT need host cell machinery to multiply

can be killed by antibiotics

infects host cells and uses host cell machinery to divide

antibiotics are not effective

lytic and lysogenic stages of a virus

lysogenic cycle

lytic cycle

4) the cell lyses, releasing phages

3) new phage DNA and proteins are synthesized and assembled into phages

1) phage attaches to host cell and injects DNA

3) bacterium reproduces normally , copying the prophage and transmitting it into daughter cells

4) many cell divisions produce a large population of bacteria infected

2) Phage DNA integrates into bacterial chromosome, becoming a prophage

2) phage DNA circularizes

1) phage attaches to host cell and injects DNA

occasionally, a prophage exists the bacterial chromosome, initiating a lytic cycle

normal immune system physiology goes DOWNHILL

chronic infection damages immune system----> leads to AIDs (CD4 cell levels reach less than 200 cells/mm^3 ; can't fight off opportunistic infections

sinse the virus destroys TH cells, b cells, t cells, and macrophages ( cells that direct the adaptive immune response) your immune system will be compromised. You will be more prone to opportunistic infections and you won't be able to fight it off. ( high death rate in general)

if AIDS is not treated you will most likely die within 3 years (your immune system physically cannot support you)

Because the immune system is damaged, and cannot fight off disease, people with AIDS get a collection of symptoms ( a ton) which is referred to as "Acquired Immunodeficiency Syndrome." This is a direct effect of HIV (compromises the immune system so badly, you tend to get sick all the time)