Chapter 22 - The Lymphatic System Flashcards
immune system
blood cells
lymphatic system
lymphatic system
– Protects us against disease
• Environmental pathogens
• Toxins
• Abnormal body cells (cancers)
lymphocytes
- Part of the immune response
- Identify, attack, and develop immunity to specific pathogens
- Make up 20–40% of WBC
- Most are stored, not circulating
immunity
• The ability to resist infection and disease
– All body cells involved in production of immunity (not just lymphatic system)
lymph tissues and organs
thymus
spleen
MALT in digestive, urinary, reproductive
respiratory (tonsils)
functions of lymphatic system
– distribute lymphocytes and other lymphoid cells
– Return excess fluid to bloodstream
– Maintain normal blood volume
– Transport hormones, nutrients, and wastes
lymphatic capillaries
– Differ from blood capillaries in several ways
• Closed at one end rather than forming a tube
• Have larger luminal diameters
• Have thinner walls
– Overlap of endothelial cells acts as one-way valve
• Allows fluids, solutes, viruses, and bacteria to enter
• Prevents their return to intercellular spaces
lymphatic capillaries have their own
endothelial cells to allow things to flow easily
lymphedema
– Blockage of lymph drainage from a limb
– Causes severe swelling
– Interferes with immune system function
lymphoid cells
– Immune system cells and supportive cells in lymphoid
tissues
Types of lymphocytes
– T cells
• Thymus-dependent
Types of lymphocytes
- B cells
• Bone marrow–derived
Types of lymphocytes
NK cells
- Natural killer cells
lymph node
functions of lymph node
-Areolar tissue with densely packed lymphocytes
-Purify lymph before return to venous circulation
• Remove 99% of antigens
antigens released due to infection
• Enter lymph and stimulate macrophages and lymphocytes in lymph nodes
Lymphoid tissues and lymph nodes
– Monitor peripheral infections
– Respond before infections reach vital organs
germinal center
contains dividing lymphocytes
Lymphadenopathy
– Enlargement of lymph nodes
– infections or cancer
swelling
response to infection
functions of the spleen
- Storage of Fe recycled from RBC
- Initiation of immune responses by B cells and T cells (in response to antigens in blood)
- attack damaged cells
2 types of immunity
Innate (nonspecific) immunity
Acquired at birth
• Always works the same way
• Against any type of invading agent
2 types of immunity
adaptive (specific) immunity
Acquired after birth
• Protects against specific pathogens
• Depends on activities of lymphocytes
• Develops after exposure to environmental hazards
in thymus, daughter cells mature into
t cells
if babies are born through birth canal and not by c section
the protective is built up very fast. born w better microbiome, better immune system
in red bone marrow daughter cells mature into
NK and B cells
immune surveillance
NK cells attack foreign cells and destroy them
Antibody-mediated immunity
B cells produce antibodies and this attacks pathogens
cell mediated immunity
T cells attack and destroy foreign cells
innate defenses
– skin
– Hair
– Epithelial layers of internal passageways
– Secretions that flush away materials
• Sweat, mucus, and urine
– Secretions that kill microorganisms
• Containing enzymes, antibodies, or stomach acid
inflammation
limit spread of infection
- stimulates clotting reaction, increases capillary permeability
- activates phagocytes
- Release of histamine by mast cells
fever
speeds up tissue metabolism and activity of defenses
phagocytes
Attack/remove dangerous microorganisms
macrophages
- Large phagocytic cells
* Make up monocyte–macrophage system
immune system perforates membrane of cells
secretion of perforin
antibiotics
puts perforins on bacteria, not on our cells
(innate defenses)
tumor specific antigens
- On plasma membranes of cancer cells
- Identified as abnormal by NK cells
- Some cancer cells avoid detection (immunological escape)
cells infected with viruses
- abnormal proteins on plasma membranes
* NK cells destroy them
necrosis
Local tissue destruction aorund injury
pus
dead and dying cells
Abscess
Accumulation of pus in enclosed space
active immunity
– Naturally acquired active immunity
– Artificially acquired active immunity
Develops after exposure to antigen – Naturally acquired active immunity • Through environmental exposure to pathogens – Artificially acquired active immunity • Through vaccine
passive immunity
– Naturally acquired passive immunity
– Artificially acquired passive immunity
Produced by transferring antibodies from another source – Naturally acquired passive immunity • Antibodies acquired from the mother – Artificially acquired passive immunity • injection of antibodies
Four properties of adaptive immunity
– Specificity
– Versatility
– Memory
– Tolerance
– Specificity
• Each T or B cell responds to specific antigen
– Versatility
• The body produces many types of lymphocytes
– Each one (clones itself) and fights a different type of antigen
– Memory
• Some inactive lymphocytes (memory cells)
– Stay in circulation
– Provide immunity against new exposure
– Tolerance
• Immune system ignores “normal” antigens
MHC proteins
- Membrane glycoproteins that bind antigens
* Genetically coded by MHC in chromosome 6
memory Tc cells
– Produced with cytotoxic T cells
– Stay in circulation
– Immediately form cytotoxic T cells if same antigen appears again
B cells attack
– Attack antigens by producing specific antibodies
– Millions of populations, each with different antibody molecules
Helper T cells
promote B cell activation
plasma cells
secrete antibodies
memory B cells
respond to next infection, like memory T cells
antibodies
mom gave specific antibodies
igG
– 80% of all antibodies
– Responsible for resistance against many viruses, bacteria, and bacterial toxins
– Maternal IgG provides passive immunity to fetus
Responses to antigen exposure
– First exposure
– Next exposure
– First exposure • Produces primary response (mild) – Next exposure • Triggers secondary response • More extensive and prolonged • Memory cells already primed
natural killer cells have short lifetime, while
neutrophils have a longer lifetime in body
macrophages- all over
antibody level takes a while
stress and immune response
Glucocorticoids
• limits immune response
• Long-term secretion (chronic stress)—inhibits
immune response and lowers resistance to disease
functions of glucocorticoids
- Depression of inflammation
- Reduces phagocytes in peripheral tissues
- Inhibition of interleukin secretion
immune disorders
– Allergies (hypersensitivities)
– Autoimmune disorders (glucose)
– Immunodeficiency diseases
Immune system diminishes with age
greater chance of infection or cancer
effects of aging
– Thymic hormone production = reduced
– T cells = less responsive to antigens
– Fewer T cells reduces responsiveness of B cells
– Immune surveillance against tumor cells declines
