1. The Lymphatic / Immune System
Biology
Unit 8
Powerpoint #7

2. Lymphatic System: Purpose:
Transports a watery fluid called lymph.
This fluid distributes immune cells throughout the body.
It drains fluid from cells and tissues

3. Lymphatic System: Functions:
Collect and return fluids, including blood plasma, to the blood, maintaining fluid homeostasis.
Defends the body against disease by producing lymphocytes.
Absorbs lipids from the intestine, and transports them to the blood.

4. Why do we need the Lymphatic System?
Every 24 hours the circulatory system slowly leaks 3 liters of blood.
Average adult has ~100,000 miles of blood vessels if you were to stretch them out in a line!
The earth’s Circumference is 25,000 miles long!

5. Lymphatic System: Structures:
white blood cells (lymphocytes)
Bone marrow
Thymus
Spleen
Tonsils
lymph nodes
lymph vessels

6. Lymph / Lymph Vessels
Lymph: fluid and protein that has been squeezed out of the blood (blood plasma).
Vessels: A network of permeable capillaries and vessels that lymph drains into.

7. Lymph Vessels
The lymph system is one-way, draining lymph from tissue, back to the blood.
Lymph movement depends on smooth muscle action, and skeletal system movement.

8. Lymph Nodes: Filters Lymph as is travels in the lymph vessels.
White blood cells are located within the lymph nodes.
Bean-shaped, size ranges from 3mm to 2cm.
Can become enlarged due to infection.
A combination burglar alarm and West Point. They guard against intruders, but also train the ‘military’ to fight.

9. White Blood Cells Bone marrow produces lymphocytes
Normally in blood, but can be found at any location.
Re-enter blood circulation through lymph vessels.
Fight foreign invaders (microorganisms)
Some last 2-5 days, others last for years.

10. Thymus:
Location of the development of T-cell lymphocytes.

11. Spleen:
Fist-sized mass of lymphatic tissue that destroys old or damaged red blood cells and platelets.

12. Immune System & Disease
Disease- any change that disrupts normal body functions (other than injury)
Causes-
Bacteria
viruses
fungi
environmental factors (smoke, lead, pesticides)
genetically inherited (hemophilia, Down's Syndrome)

13. Infectious diseases are caused by microorganisms
Germ Theory of Disease
Proposed by Louis Pasteur & Robert Koch
Infectious diseases are caused by microorganisms

14. Agents of Disease
Virus- tiny particles that invade & replicate within living cells
Is not alive, only a piece of DNA or RNA bound in a protective coat

15. Agents of Disease Bacteria- single celled organisms (prokaryotic)
Most don’t cause disease
Those that cause disease attack cells directly or produce toxins that harm cells

16. Agents of Disease
Protists- tiny single celled organisms that spread via insects, blood, food, or water
Examples: Malaria, Sleeping sickness, traveler’s diarrhea

17. Agents of Disease
Worms-- flatworms & roundworm eggs that grow inside other organisms
Examples: Schistosoma
Ascaris
tapeworm

18. Agents of Disease Fungi– most are harmless Tinea attacks the skin
causes athlete’s foot &
ringworm

19. Spread of Disease
Coughing, sneezing, or physical contact
Contaminated food & water
Animals

20. Fighting Infectious Disease
1. Antibiotics– compounds that kill bacteria without harming host cells
Many are produced naturally by organisms (like mold creates penicillin) discovered by Alexander Fleming
2. Antiviral drugs– inhibit their ability to invade cells
3. Rest & fluids so your own immune system can work well!

21. The Immune System
Immunity- fighting off disease before it actually makes you ill
2 categories:
Specific- targeted for 1 disease
Nonspecific- general line of defense against anything

22. Defense First line of defense Skin
Layers of dead cells are hard to penetrate
Oil and sweat  acidic environment kills many bacteria
Mucus: traps dirt and pathogens
Stomach acid: destroys pathogens
Secretions (tears, sweat): lysozyme breaks down cell walls of bacteria

23. 2nd line of defense Inflammatory response–
Phagocytes (white blood cells)
go to site of injury to engulf foreign agents
2. Fever can slow down growth or stop growth of some pathogens (also ‘s heart rate to get WBC’s to site faster)
3. Interferon proteins help cells resist viruses by slowing down their replication in cells

24. II. Specific Defenses Humoral Immunity
Antigen: molecule on the surface of foreign cells that causes an immune response
Antibody: protein that binds to antigens to mark pathogens for destruction
Macrophage: large white blood cell that engulfs foreign cells
Phagocyte: white blood cell that engulfs foreign cells

25. Step in Immune Response
Labeled Drawing
1. Pathogen invades the body
2. Macrophage samples foreign cells, engulfs pathogen.

26. Step in Immune Response
Labeled Drawing
3. Antigens from the pathogen are displayed on the surface of the macrophage.
4. T-cell recognizes and is activated by the amino acid sequence of the antigens on the macrophage. Activated T-cell replicates.

27. Step in Immune Response
Labeled Drawing
5. T-cells activate B-cells which make antibodies.
6. Antibodies bind antigens on pathogen – inactivate pathogen and mark it for destruction by phagocytes.

28. Step in Immune Response
Labeled Drawing
7. Phagocytes consume labeled pathogens.

29. II. Specific Defenses
Permanent Immunity: once the body has been exposed to a specific pathogen, memory B and T cells remain capable of producing antibodies to that pathogen

30. II. Specific Defenses
C. Vaccination: injection of a weakened form of a pathogen to produce immunity
1. active immunity: produced by vaccine; body is capable of producing antibodies to a pathogen
2. passive immunity: antibodies produced by another organism are injected; recipient is immune as long as antibodies remain in circulation
3. maternal immunity: antibodies are passed from mother to fetus or infant; similar to passive immunity

31. Passive Immunity
Lasts only a short time because they are not created by the body’s own immune system
Examples:
1) Mother passing antibodies through placenta or breast milk to baby
2) Vaccines with antibodies against diseases like malaria, yellow fever, rabies

32. HIV & T-cells
HIV replicates inside T- cells, and then destroys them as they burst open to release more viruses
When Immune cells are destroyed, other diseases & infections can weaken & kill AIDS patients

33. Immune System Disorders
Allergies- overreactions of immune system to antigens
Mast cells are specialized cells that initiate the inflammatory response
Histamines- chemicals released by mast cells that increase blood flow & fluids to the area
This causes sneezing, watery eyes, & runny nose

34. Autoimmune Diseases Body attacks the body’s own cells
Examples: Type I diabetes, rheumatoid arthritis, myasthenia gravis, & multiple sclerosis (MS), Lupus