1. Lymphatic System and Immunity
The super cool ways your body keeps you healthy

2. What is it?
It is a network of vessels that assist in circulating body fluids
It is made up of different types of cells and proteins that all have a different job

4. What does it do? Transports excess fluid away from interstitial spaces
Transports fluid to the bloodstream
Transports digested fats to the bloodstream
Defends the body against foreign invaders

6. What is its pathway? Begins as lymphatic capillaries
Capillaries merge to form lymphatic vessels
Lymph is passed through the lymph nodes while in the lymphatic vessels
Vessels merge to form lymphatic trunks
Lymphatic trunks join one of two collecting ducts
Collecting ducts transport lymph into venous system through the subclavian veins
Venous system carries it as plasma in blood’s return to the right atrium

9. What is LYMPH?
Our blood capillaries tend to seep fluid into the surrounding tissues
This fluid contains food that must be taken to the cells and waste that must be taken away from the cells
Although this fluid is important, if it builds up, it causes edema
The lymphatic system drains off this fluid so that there is no swelling!
Once this fluid is in the lymphatic system, it is called lymph
Lymph is composed of proteins, fats, foreign particles, gases, hormones, and other small molecules

12. Lymph Nodes
Bean-shaped masses of lymphatic tissue located in groups along the lymphatic vessels
Filter lymph by getting rid of any potentially harmful material
Contain many lymphocytes and macrophages which attack the harmful particles
Afferent vessels bring lymph into the node; efferent vessels carry lymph away from the node
Several major regions of clusters, including the cervical region and the axillary region

15. Lymphatic System Organs
Thymus (thymus gland):
Located between lungs, above heart, behind sternum
Provides place where some inactivated lymphocytes called thymocytes can mature into T-lymphocytes
Spleen:
Located under the left side of diaphragm
Contains two types of tissues
1. red pulp: contains red blood cells; filters blood of any unwanted particles
2. white pulp: contains lymphocytes; helps fight infections

16. Lymphatic System Organs
Lymph Vessels
Located parallel to veins, branch throughout body
Provides unidirectional transport from tissues to the heart
Tonsils
Are masses of lymphatic tissues, produce lymphocytes and filter bacteria

19. Innate (nonspecific) defenses
Species Resistance: diseases are unique to a certain species; another species cannot get that disease
Mechanical Barriers: prevent entrance of infectious agents; skin first line of defense

20. Innate (nonspecific) defenses continued
Chemical Barriers: enzymes, low pH, excess salt can destroy bacteria
Interferons: proteins that tell other cells to block viral replication
Defensins: proteins that destroy bacterial cells by making holes in the cell walls
Collectins: proteins that detect and bind to sugar molecules on pathogens, making the pathogens more easily phagocytized

21. Innate (nonspecific) defenses continued
Fever: lymphocytes send signal to hypothalamus to maintain a higher body temperature
Higher temp makes liver and spleen retain their iron, which the viral and bacterial cells can’t survive without
Natural Killer (NK) Cells: secrete perforins which cause cell walls of viral and cancer cells to disintegrate

22. Innate (nonspecific) defenses continued
Inflammation: Tissue response of localized redness, swelling, heat, and pain that kills pathogens in the area, prevents spread of pathogens, and promotes healing
Phagocytosis: Removes foreign particles from lymph, blood vessels, and tissues by engulfing and digesting foreign particles and cells

24. Naturally Acquired Immunity
Naturally acquired passive immunity is immunity you get from your mother while still in the womb
Some of the antibodies your mother has acquired over her lifetime gets passed through the placenta to the fetus
The other type of naturally acquired immunity is your body’s response to the antigen (discussed later)

25. Artificially Acquired Immunity
Artificially acquired immunity is the immunity we get from vaccinations
Vaccinations can be the transfer of antibodies, or they can be injection of a non-active form of a virus
Transfer of antibodies can be used for things like snake bites, as a treatment
Vaccinations are used prophylactically in hopes of preventing you from getting something

26. Vaccinations

27. Vaccinations 1st vaccination: small pox “vacca” = cow
Started in India or China before 200 BC!
“vacca” = cow
First vaccine was against small pox and was taken from a cow virus called cowpox

28. What Are Vaccinations?
Vaccinations are usually either inactivated or weakened forms of a virus
Your body produces antibodies in response to these inactivated or weakened viruses
Some of these antibodies are the Memory T and B cells, which stay with you for a very long time

29. Vaccination Schedule
In the US, we have a vaccination schedule for infants and minors
Vaccination schedule is from the American Academy of Pediatrics
Everyone is required to follow this, except for religious reasons
Most vaccinations are required in the first year of life
The rest are required by the age of 5-6
Most vaccinations have to given again in adolescence, before the age of 18
Some also depend on the state you live in

30. Vaccination Debate
Some people believe that early childhood vaccinations cause autism
Some of these people are trying to refuse to give their children vaccinations
The problem with this is that if we have too many unvaccinated children, the diseases that we have essentially eradicated may come back