Immune System Flashcards
What is the 1st Line of defence?
Trachea (Physical): There are some specially adapted cells in our trachea (windpipe) which contain cilia (hair like projections). There are mucus producing cells mixed in with the ciliated cells to help keep a fresh lining of mucus in our airways. This sticky layer of mucus traps the majority of microorganisms and large particles which enter our body.
Cilia (Physical): Sweeps the mucus containing the trapped microorganisms into the stomach.
Eye Lashes (Physical): act as a barrier which protects the eye when it is open.
They trap dirt and microorganisms preventing them from entering the eye and causing infection.
Tears (Chemical): Have a high salt content that essentially desiccates or “dries up” and washes out microorganisms.
Hairs Nose (Physical): Contained in the nostrils helps to trap the larger particles in a sticky layer of mucus (snot). This is can then be removed from the nose through blowing or swallowing the mucus, which is then taken care of in the stomach.
Skin (Physical and chemical): Different layers of skin block microorganisms. The top layer (dead epidermis) sheds all the time. Getting rid of old skin means we are also getting rid of a lot of the microorganisms.
Stomach Acid (Chemical): contains an acid called hydrochloric acid (HCl). This acid is used to breakdown food, it has a pH of 2 and is very corrosive. The stomach coated with a special lining to prevent the acid corroding the wall away.
Scabs (Physical): Are formed from blood clotting.
When you get a wound special blood cells called platelets stick together and react with other proteins to build a clot.
What is the 2nd line of defence?
Despite the physical and chemical barriers of the body’s first line of defence, some pathogens may enter the body only if the 1st line falls does the 2nd act.
Second line of defence consists of:
• inflammation – blood capillaries widen and more blood flows to the scene
• white blood cells – phagocytes engulf and destroy pathogens.
1st Step:
Inflammation: Blood flows to area in response to help signals from cells in the area around the pathogen – brings platelets for clotting and white blood cells to area.
2nd Step: Engulfing Pathogens called Phagocytosis
Non-specific immune system is when white blood cells attack microbes that get into your body and surround the microbe, digesting it.
What is the 3rd line of defence?
White blood cells produce antibodies. These help you fight pathogens.
When they find the antigen of a foreign body, they lock onto it and destroy it.
There is a different antibody for every antigen.
The immune system includes white blood cells are called lymphocytes and they are specific by only recognising one pathogen.
Your body only knows what shape to make the antibodies after you have caught the disease and become ill.
The lymphatic system is part of the 3rd line of defence, what is it? (Antibodies, t-cells, b-cells).
Lymphatic System.
- Pathogen specific defence.
- Antibodies, T-Cells and B-Cells.
Lymphocytes are a type of white blood cell found in the blood or lymph nodes and made by bone marrow. There are several types of lymphocytes, such as:
T-Lymphocytes recognise antigens on pathogens and either attack them directly or co-ordinate the activity of other cells of the immune system.
B-Lymphocytes recognise antigens (an invader) and produce special chemicals called antibodies.
Anti-bodies are special Y-shaped proteins produced by B-lymphocytes in response to specific antigens.
Antibodies work by binding antigens on pathogens ‘labelling’ them and causing them to clump together.
The pathogen can be destroyed by:
Phagocytosis by macrophages.
T-lymphocytes
The antibodies themselves.
What are the steps to phagocytosis?
Stage 1: White blood cells recognises the pathogen.
Stage 2: The macrophage (white cell) engulfs the pathogen.
Stage 3: Toxic Chemicals, acidic enzymes.
Stage 4: Bacteria is broken down and destroyed.
Stage 5: Bacteria destroyed and waste expelled from macrophage. (The useful material is kept).
What does a pathogen introduce to our body?
Pathogens once enters into our body introduces a new antigen and for every new antigen the body needs to build a specific antibody to grab the antigen and defeat it. Vaccines help with this.
What is the lifecycle of a virus?
1st: the virus attaches to a host cell.
2nd: The viruses DNA is inserted into the cell and replicates
3rd: The phage particles mature and assemble.
4th: The phage particles are released and go out into the body to repeat the process.
