Chapter 15 Lymphatic system and Immunity Flashcards
What is the lymphatic system?
- Critical for circulatory system function and immune system
- Fluid recovery (maintain blood pressure)
- Site of immune cells (disease fighting cells)
What are two parts of the lymbic system?
- Two parts:
- Network of vessels that extends to all tissues of the body
- Organs and tissues that produce and maintain immune cells
- Organs and tissues include:
Lymph vessels/nodes, tonsils, thymus, spleen, bone marrow
- Organs and tissues include:
Why is there fluid recovery?
- Capillaries are “leaky”
- 2-4 liters of water diffuse into tissues daily
- Called interstitial fluid
- Lymph vessels absorbs interstitial fluid
- Transport back to blood vessel
How many liters of blood do humans hold?
Humans 4-6 liters of blood
What is Elephantiasis?
- A parasite infects lymphs vessels and prevents reabsorption of lymph fluid
- Leads to edema in limbs and over time the skin stretches and thickens (testicles and breasts can also be affected)
What are lymph nodes and how are they related to immunity?
- Interstitial fluid is filtered by lymph nodes for pathogens
- Bean-shaped structures of lymph tissue
- Contain lymphocytes that help with immunity
- Lymphocytes are a subset of white blood cells
- When sick, lymph nodes become swollen and painful
- This occurs because the body is issuing an immune response
How is resistance organized?
- Pathogens are disease causing organisms
- Bacteria, viruses, parasites, fungi
- Body has two mechanisms to deal with pathogens:
- Nonspecific Immunity(attack any foreign invaders):
- External Barriers
- Phagocytic Cells
- Immunological Surveillance
- Complement System
- Specific Immunity(attack a SPECIFIC foreign invader):
- Cell-mediated resistance
- Antibody-mediated resistance
How is resistance organized?
Creates a “layered” approach to protection
What are white blood cells also known as and what are they?
- White blood cells are known as leukocytes
- Also produced in red bone marrow
- Only about 5,000-10,000 cells per drop of blood
- Retain organelles
- Cells of immunity
- Two subsets based on original stem cell
- Neutrophils, monocytes, macrophages basophils, eosinophils ~70% of white blood cells
- Lymphocytes (B and T cells, natural killer cells) ~30%
Which of the following is an example of a non-specific defense?
A. Antibodies causes agglutination
B. Cells searching for a pathogen with a known antigen
C. The mucous membrane of your nose
What are the three nonspecific resistances?
- External barriers
- Integumentary system (skin): dryness, acidity
- Mucous membranes: “traps” pathogens
- Phagocytic cells
- Remove pathogen by engulfing them
- Immunological Surveillance
- Natural killer cells
- Recognizes any abnormal antigens
- Recognitions results in destruction of the pathogen OR infected cell by lysis
What is a result of nonspecific resistance?
FEVER
- Increase in body temperature
- Caused by pyrogens
- Proteins released by macrophages during phagocytosis
- Results in hypothalamus “resetting” body’s thermostat
- Aspirin or ibuprofen prevents pyrogens from delivering message to brain
- Increases metabolism
- Fevers are a natural response to infection…may be beneficial!
Lymphocytes play a direct role in non-specific immunity.
A. True
B. False
What does specific Resistance equal?
IMMUNITY
- Resistance directed towards a specific pathogen
- Body also develops “memory” of pathogen for future protection
What are the two types of immunity?
Two types of immunity
- Cell-mediated immunity infected cells/pathogens are killed by specific T-cells
- Antibody-mediated immunity infected cells/pathogens are killed by antibodies produced by B-cells
- Two systems are coordinated by Helper T-cells
What happens at step one?
Step 1 – Antigen Presentation
- First step Antigen Presenting Cells (APC’s)
- Protein complex on surface “presents” antigens to T cells
- Class I MHC – all nucleated cells in your body
- “HELP – I’M INFECTED!!! KILL ME!!!”
- Class II MHC – macrophages, B cells
- “WARNING – HERE’S A BAD ANTIGEN. FIND AND DESTROY!!!”
What is activated in step two and what does it do to the memory? (Part two)
- Activated Th cells secrete cytokines
- Cytokines help stimulate Tc cell and B cell activation
- Help stimulate non-specific responses
- Integrate cell-mediated, antibody-mediated immunity and non-specific
- Activation also causes differentiation of memory Th cells
- Faster response than naïve cells with next encounter of same antigen
Overview of T-Cell Activation
What is activated at step 4?
Step 4 – B-Cell Activation
- B cells have antibodies for specific antigens on cell surface
- Sensitization Antigen binds antibody, engulfs antigen, presents antigen
- Activation Bind Th cell activated with same antigen, “Co-stimulation”
- This is a required step to prevent an accidental activation
- Produce plasma cells make and secrete antibodies
- Produce memory B cells faster response if exposed to antigen again
