Human Immune System Notes

Human Immune System

Just by moving around, you are continuously breaking some vessels which lose blood onto the interstitial fluid. A mechanism is needed to stop that blood escape

Notes on: Blood Clotting Mechanism

Notes on: Blood Clotting Disorders

Anticoagulant Drugs

Immune System (human immune system)

Non-Specific Immunity response

Epithelial layers are our barriers
Skin is exposed to the most pathogens, so the skin is packed with a lot of keratinized simple squamous
Mucous lining helps us in respiratory tract

Saliva, mucous and tears contain enzymes that provide a barrier against pathogen and destroy pathogen

Gi tract, the stomach acids can destroy pathogens
Blood clot is non-specific
Inflammations are non-specific, causing more blood flow bringing in more white blood cells.
Fever, altered temperature, makes it hard for some pathogens to grow

Specific Immunity

Hematocrit is the percentage of blood that is erythrocytes

Higher amount for men

Antigen (Ag)

Is an antibody generator
These are large molecules with 3D shape
Proteins (largest amount group), glycoproteins and polysaccharides
Nonpolar hydrocarbons are not good enough to be antigen
Large molecules that act as a toxic can be an antigen
One molecule may have multiple antigenic sites that can act as antigens
We can have billions of different antigens
Viruses can be antigens as well.

Viruses need a host to live and reproduce. Therefore, viruses are not living creatures. However, they do have nucleic acids because they do have DNA and RNA, but they don’t have a cell membrane. Instead, they have a protein coat or viral coat.

Antibodies (Ab)

Proteins made by B lymphocytes
Bind to specific antigens
They are Y shaped
They have a region called constant (or Fc)
They have a region called variable regions. This region is where the antigen binds. The variable regions are very specific, that is why antibodies bind to specific antigens
We can have millions of different antibodies

5 classes of Antibodies

The differences between the classes is that each of them have a different constant region

IgG (Immunoglobin)
IgA

Main antibody type in external secretions, such as saliva and mother’s milk

Humoral Immunity (human immune system)

Trigger the phagocytosis of Antigen-Antibody complex

B-cells humoral immunity

The antibodies can cluster around and cover up a toxin or virus, which inactivates toxins/virus

Activate complement System

Membrane attack complex

You create a hole in the foreign cell of the bacteria in the cell membrane, water rushes in and burst (lyse) the cell

Chemotaxis of Leukocytes

Chemicals released that tells the white blood cells to come to the infection area

Stimulation of phagocytosis in the macrophages and neutrophils (neutrophils have lysosome)
Mast cell release Histamines, more white blood cells come to fight infection.

Prostoglandin concentration also increase causing swelling to increase
Histamine and prostaglandin are regulated by positive feedback

Antibody Production

Made by Clonal selection

Stem cell is produced. Stem cell differentiates into different B cells. The B cells are called Virgin B cells (made 1 yr after birth). These virgin B cells make different antibodies. A specific antigen will be exposed a specific virgin B cell. In response, more of this specific virgin B cell will be produced

Plasma Cells

Antibodies that floating into the blood stream

Memory Cells

There are cells that copy and remember specific antibodies, and can produce this antibody later on in a person’s life

Antiserum—antibodies raised in animals

You take a particular antigen injected into an animal. The animal produces an antibody. You use that antibody for humans. Some examples: snake bites. The toxic venom is an antigen; your immune system can’t make antibodies quick enough. That is why you use antiserum.
Antiserum works very short term
Your immune system recognizes that these antibodies from an antiserum are not yours (foreign), so your immune system destroys them thinking that those antibodies are actually antigens.
If you get a snake bite, you have to get an antiserum from a different animal.

Role of T Cells (human immune system)

T-Helper
T-Helper present antigens to B cells
Cytotoxic T cells
Suppressor T Cells
Natural Killer T Cells

Not really T cells
They destroy our body’s damages cells by understanding that these cells were infected by foreign material

Cytotoxic T cells and T-Helper cells recognize self form from non-self using HLA and MHC proteins.

These proteins sit on a plasma membrane of a cell. Everyone has different MHC and HLA proteins, except identical twins.

These proteins are used during transplantation of organs

These T cells also produce interleukins and interferons
Helper T cells and Cytotoxic T cells also recognize cancerous cells

Immune System suppression

T-suppresor cells
Decrease antibody formation
Secrete substances that decrease the effectiveness of Cytotoxic T cells
Also makes T helper less effective
Helps release cortisol which decrease immune system (and you are less able to fight infections)

Stress, sympathetic nervous system, tissue damage, infection, extreme heat/cold cause the release of cortisol. Release of cortisol makes you more likely to be sick
Cortisol: decreases number of T cells, decreases lysosome activity (affects macrophages and neutrophils), decreases permeability of capillaries, decreases inflammation

End of Human Immune System Notes

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