What are the 3 main roles of the lymphatic system?
- Maintain fluid balance
- Transport lipids
- Protect against infection
What are pathogens?
Microscopic organisms that can cause harm to the body
What is the defense system?
A system that activates when pathogens enter your system in order to protect against the pathogens
What are the 3 lines of defense?
- Barriers
- Non-specific defenses
- Specific defenses
Describe the 1st line of defense
Surface barriers that prevent pathogens from entering the body
What are the different components of the 1st line of defense?
- Physical: eyelashes, cilia in respiratory tract, nose hairs
- Chemical: mucus, tears, stomach acid, precipitation
- Skin: hostile environment for microorganisms
Describe the 2nd line of defense
- The non-specific cellular and molecular responses of the immune system (does not involve antibodies)
- Defences do not differentiate between different pathogens (respond the same way for each infection)
What are the different components of the 2nd line of defense?
- Natural killer cells (target cancerous or infected body cells and perform phagocytosis: engulf foreign bodies)
- Inflammatory response (damage to tissue causes release of histamine and cause capillaries to swell and leak, releasing phagocytes)
- Fever (WBCs release chemicals, triggering the hypothalamus to increase body temperature,
causing WBCs to work better and viruses/bacteria to weaken
Describe the third line of defense
- During fetal development the body makes a list of all “self” particles (antigens that belong)
- Antigen receptors (same shape as antibodies) on B and T cells recognize foreign antigens, and bind to them and neutralize them
- If we come into contact with the same antigen again, the immune response will be faster
What are T-cells?
They are lymphocytes (a type of WBC) that develops in the thymus gland. They recognize pathogens and activate immune responses
What are the different types of T-cells?
Helper T cells
Killer T cells
Suppressor T cells
Memory T cells
What do helper T-cells do?
Recognize antigen from chemical signals and stimulate more phagocytes/macrophages, B cells, and T cells
What do killer T-cells do?
Bind, puncture, and destroy infected cells; essentially “self-destruct”
What do suppressor T-cells do?
Slows/turns off immune response to protect healthy tissues after invader is killed off
What do memory T-cells do?
Do not respond on first exposure, but remember pathogen and remain in blood for future invasion
What are B-cells?
They are lymphocytes (a type of WBC) that mature in bone marrow. When they are activated, the cell enlarges and divides into memory B and plasma cells
What is the role of a plasma cell?
Produce and release large amounts of antibodies (200/sec) that will match the foreign invader’s antigen and bind to it, disabling the pathogen
What is the role of a Memory B-cell?
Remembers the pathogens after the infection is gone, and stays in blood ready for them to attack again
What is an autoimmune disorder?
When T cells or antibodies mistakenly attack the body’s own cells
What are allergies? What are the two types?
Exaggerated immune response to a harmless material. The two types are acute and delayed
Describe an acute allergy
Reaction occurs within seconds;
antibodies trigger release of histamines, causing swelling, watery eyes, runny nose, etc.
