The Immune system - The lines of defense and Vaccinations Flashcards
When does an infection happen and what happens when it enters our body?
An infection occurs when a pathogen enters the body and reaches its target cells. When an infection bypasses the 3 lines of defence, we get sick. Depending on the species of pathogen, an infection can occur in various ways.
What is the Immune system and what does it consist of?
The immune system helps prevent infections and consists of 3 main lines of defence.
Explain what is the responsibility of the first line of defense.
The first line of defense is designed to prevent the entry of the pathogen. (Barrier)
What are the mechanisms to prevent the pathogen from entering the body?
skin ( a barrier between pathogens and tissue), fluids ( tears and saliva wash away pathogens and are antiseptic, helps prevent the growth of pathogens), hair and mucus ( inside the airway to prevent pathogens from entering the lungs), acid ( in the stomach to kill some pathogens - hydrochloric acid) and emptying the digestive tract through vomiting or diarrhoea to remove pathogens.
Explain what is the responsibility of the second line of defence.
The second line of defense involves non specific cellular responses. (General response to any infection.
What are the mechanisms used in this line?
The mechanisms include specialised white blood cells (WBC) called neutrophils and macrophages where they move to the area and engulf the pathogens. When these cells become full, they die and form yellow pus at the infection site. Additionally cells near the infection site release histamine which increases blood flow to the area bringing more white blood cells and making the area red, swollen and can heat. (Inflammation)
What are white blood cells also called?
Phagocytes.
Explain what is the responsibility of the third line of defence.
The third line of defense is composed of specific cellular responses and involves the lymphatic system.
What is the lymphatic system?
The lymphatic system is made of tissues called lymph nodes and blood vessels that move fluid around your body and to the heart.
What does lymph nodes hold?
Lymph nodes contains specialised white blood cells called lymphocytes that produce proteins called antibodies which can:
Bind specifically to the pathogen and cause them to clump together. Signal the macrophages to come and engulf the pathogen.
What happens to your body after infection?
Your body retains to antibodies after infection, building an immunological memory. In this way you can be immune to diseases.
What does vaccines rely on?
Vaccines rely on the memory capabilities of our immune system and allow us to pass on immunity artificially.
What may vaccines be made out of?
Vaccines may be made out if dead/inactive pathogens (bacteria or viruses) and their proteins still triggering the third line of defence and building memory but not making us dangerously sick.
