Lymphatic system Flashcards
What are microorganisms that reside on and in the human body called?
Microbiome
The term refers to the diverse range of bacteria, viruses, fungi, and other microbes that inhabit the human body.
What is the immune system?
Cell population that inhabits all organs and defends the body from pathogens
The immune system plays a critical role in protecting the body from infections and diseases.
What are the three main functions of the lymphatic system?
- Fluid recovery
- Immune Surveillance
- Lipid absorption
These functions are essential for maintaining fluid balance, monitoring for pathogens, and absorbing dietary fats.
What is lymph?
Clear, colorless fluid similar to plasma, but with much less proteins
Lymph is crucial for transporting immune cells and draining excess interstitial fluid.
Where are lymphatic capillaries found?
In almost all tissues of the body
Lymphatic capillaries are essential for collecting interstitial fluid and initiating lymph flow.
What are the three layers of lymphatic vessels?
- Tunica interna
- Tunica media
- Tunica externa
These layers are similar to those found in arteries and veins, providing structural support.
What is the flow path of lymph?
Lymphatic capillaries 🡪 collecting vessels 🡪 11 lymphatic trunk 🡪 2 collecting ducts (right lymphatic and thoracic) 🡪 subclavian veins
This pathway is crucial for returning lymph to the circulatory system.
What are neutrophils?
Antibacterial cells, that are part of inate immune response.
Neutrophils are a type of white blood cell essential for the innate immune response.
What are the primary lymphatic organs? and what does it mean to be a primary lymphatic organ?
- Red bone marrow: platelets, WBC, Hematopeosis, sinuses for blood to enter bloodstream
- Thymus: Maturation of T lymphocytes
Primary lymphatic organs are where cells BECOME immunocompetent (able to recognize and respond to antigens)
These organs are where immune cells become immunocompetent.
What is lymphadenitis?
Swollen, painful lymph node responding to foreign antigen
This condition indicates that the immune system is actively fighting an infection.
What is our immune systems the 3 lines of defense against a pathogen
first line: Skin and mucous membranes
Second line:Nonspecific immunity, protects against pathogens that break the skin and mucous membrane barrier
Third line: specific adaptive immunity, targets specific pathogen and provides memory
What is innate immunity?
Defenses we are born with; protect us from a broad spectrum of disease agents.
Nonspecific, local effect at invasion point, lack memory
What are the four cardinal signs of inflammation?
- Redness
- Swelling
- Heat
- Pain
These signs indicate an active immune response to injury or infection.
What is the role of antibodies?
Defensive proteins in plasma
Antibodies help identify and neutralize foreign objects like bacteria and viruses.
What is the function of the spleen?
- Erythrocyte graveyard
- Blood cell production in fetus
- Immunity
The spleen plays multiple roles in filtering blood and supporting the immune system.
What is natural active immunity?
Produce antibodies/T cells as a result of a natural infection (sickness)
This type of immunity is developed through natural exposure to pathogens.
What is the difference between positive and negative selection in T lymphocytes?
- Positive selection: ensures T cells respond to foreign antigens
- Negative selection: ensures T cells do not react to self-antigens
These selection processes are critical for developing a functional and self-tolerant immune system.
What triggers the secondary immune response?
Re-exposure to the same pathogen
This response is typically faster and more robust due to memory cells.
What is the main antibody in the primary immune response?
IgM
IgM is the first antibody produced in response to an infection.
What are the types of hypersensitivity?
- Type I: acute (e.g., allergies)
- Type II: cytotoxic
- Type III: immune complex
- Type IV: delayed
These hypersensitivity reactions can lead to various allergic and autoimmune conditions.
What is antibody titer?
Level of antibodies in the blood plasma
What occurs during the primary immune response?
First exposure, longer time to produce antibodies (IgM), and you feel sick
What is the secondary immune response?
Re-exposure, quick reaction time to increase antibody titer (IgG), usually no illness
Define hypersensitivity.
Excessive immune reaction against antigens most people tolerate
What is alloimmunity?
React to transplanted tissue
What is autoimmunity?
Abnormal reaction to one’s own tissue
List the four kinds of hypersensitivity.
- Type I: acute
- Type II: antibody-dependent
- Type III: immune complex
- Type IV: delayed
What is Type I hypersensitivity?
Acute; example: allergies and asthma. IgE mediated, basophils, mast cells
What happens in asthma?
Inhaled allergen causes inflammation of airway, plasma cells secrete IgE
What is anaphylaxis?
Widespread vasodilation, epinephrine relieves, bronchoconstriction
What is Type II hypersensitivity?
Antibody-dependent; example: blood transfusion reactions. IgG or IgM
What is Type III hypersensitivity?
Immune complex; example: lupus erythematosus, acute glomerulonephritis
What is Type IV hypersensitivity?
Delayed; example: TB skin test, poison ivy
What characterizes autoimmune disease?
Fails self-tolerance; produces autoantibodies that attack body’s own tissues
What is cross-reactivity?
Antibodies react to self antigens
What causes immunodeficiency?
Immune system fails to react vigorously enough
What is Severe Combined Immunodeficiency Disease (SCID)?
Genetic lack of T and B cells (no memory cells)
What causes AIDS?
Caused by HIV and destroys helper T cells
What is a potential consequence of a Covid-19 infection?
Cytokine storm, which produces excessive hyperinflammatory response
what are the mechanisms that enable flow through the lymphatic system
Rhythmic contractions of lymphatic vessels
skeletal muscle pump
thoracic pump
Valves
what are Natural killer (NK) cells
lymphocytes that attack and destroy infected host and cancer cells
T cells
cells developed in thymus. adaptive immune system.
Helper T cells (CD4+): activate other immune cells, B cells, cytotoxic T cells. They play a key role in coordinating the immune response.
Cytotoxic T cells (CD8+): Directly kill infected or cancerous cells by recognizing specific markers on their surface.
Regulatory T cells (Tregs): Prevent autoimmune reactions by suppressing overactive immune responses.
what are B cells
Develop and stay in bone marrow. Part of adaptive immune response
when activated by antigen, becomes plasma cells and produce antibodies, recognize and neutralize foreign substances like bacteria, viruses, and toxins. “tag” pathogens for destruction by other immune cells.
Memory B cells
Which cells are antigen producing cells and what is their function?
cells that encounter and antigen, engulf it, and display it’s epitopes in the MHC protein.
This activates T cells to initiate an immune response if an APC displays a foreign antigen
Dendritic cells: found in skin, mucous membranes, lymphoid organs. Present MHC-2 to Helper T cells
Macrophages: Present MHC-2 to Helper T cells
B cells: Present MHC-2 to Helper T cells
What are the 2 types of lymphatic tissue
a. Diffuse lymphatic tissue: MALT (Mucosa associated lymphoid tissue): scattered lymphocytes (not close together), present in body passages open to exterior (respiratory,digestive,urinary,reproductive). Mucous membranes
b. Lymphatic nodules: dense mass of Lymphocytes and Macrophages. Aggregated lymphoid nodules (“Peyer patches”). small intestines
WHat are secondary Lymph organs? Function?
cells are already immunocompetent
Lymph nodes, tonsils, spleen
Name the 3 tonsils and location
- Palatine: posterior margin or oral cavity
- Lingual: each side of base of tongue
- Pharyngeal (adenoids): on wall of pharynx
Lymph nodes
a. Cervical neck , Axillary armpit, Thoracic cavity (especially mediastinium), Abdominal, intestinal, and mesenteric, Inguinal groin, Popliteal back of knee.
Afferent vessels= fluid into vessel (arriving)
Efferent vessels= Fluid out vessel (exiting)
Lymphadenitis: swollen, painful lymph node responding to foreign antigen. (fighting off disease)
Lymphadenopathy: term for all lymph node diseases
explain the spleen
Red pulp: sinuses filled with RBC (erythrocytes)
White pulp: WBCs Lymphocytes, Macrophages
Functions:
a. erythrocyte graveyard
b. blood cell production in fetus
c. immunity (Lymphocytes and Macrophages)
d. stabilizes blood volume through plasma transfers to lymphoid system
what is adaptive immunity
immune response. developed upon exposure, require prior exposure to pathogen but maintain immune memory
i. Has a systemic effect
ii. Exhibits adaptive protection and immunity to specific pathogens
iii. Has immunological memory: when re-exposed to the same pathogen the body reacts so quickly that there is no feeling of being sick
what are the external barriers of the first line of defense against pathogens
a. Skin
i. Toughness of keratin creates a physical barrier
ii. Defensins,dermcidin, cathelcidins: peptides in skin that kill microbes
iii. Acid mantle: film of lactic acid and fatty acids from sweat and sebum that inhibit bacterial growth
b. Mucous membranes
i. Mucus traps microbes
ii. Lysozyme: enzyme that destroy bacteria cell wall
c. Subepithelial areolar tissue
i. Hyaluronic acid
ii. Hyaluronidase- makes hyaluronic acid less viscous= easier penetrate
what is the compliment system and what line of defense is it?
2nd line of defense: antimicrobial proteins
group of 30 proteins that when activated cause:
1. Inflammation- basophil secrete histamine secretion, activate/attract neutrophils/macrophages
2. Immune clearance- macrophages destroy antigen-antibody complexes
3. Phagocytosis- Opsonization (increase binding site for phagocytosis)
4. Cytolysis- membrane attack complex=> hole in membrane=> cell repture
what are the cellular defenses that make up the second line of defense against pathogens
Leukocytes,
Antimicrobial proteins (warn neighboring cells of viral invasion. Activate NK and macrophages, stim. Synthesis of antiviral proteins
Immune Surveillance: done by the Natural killer (NK) cells. Patrol looking for diseased cells
Fever: Promote interferon activity, accelerate tissue repair, elevate metabolism, inhibit reproduction of bacteria/ viruses. Pyrogens
Inflammation: redness, swelling, heat, pain. Cytokines= communication
during inflammation, how is the mobilization of body defenses achieved
local Hyperemia (increase BF) and local vasodilation
leukocyte recruitment through
a. Margination: makes membranes sticky so WBC stick to vessel wall
b. Diapedesis (emigration): WBCs exit gaps in capillaries and enter tissue fluid
what are the steps of Containment and destruction of a pathogen
- Fibrinogen forms a stick mesh to enclose microbes
- Heparin prevents clotting
- Neutrophils exhibit chemotaxis: attracted to chemicals (bradykinin, leukotrienes) that guide them to the injury site
- Neutrophils kill bacteria; secrete cytokines, phagocytosis, respiratory burst, Macrophage & Tcell=leukopoesis,
Explain tissue repair after destruction of pathogens
Platelet-derived growth factor secreted by platelets to stimulate tissue growth and repair
a. Hyperemia deliver necessities for protein synthesis
b. Increased metabolic rate increases mitosis and tissue repair
c. Fibrin clot forms scaffold for tissue repair
d. Pain reminds us to let heal
how are tissues cleaned up after the destruction of pathogens
edema drains tissue fluid into capillary vessels
Monocytes come clean everything up
What are the forms of adaptive immunity
i. Natural active immunity: produce antibodies/ T cells as result from infection
ii. Artificial active immunity: produce antibodies/ T cells as result vaccines and booster shots
iii. Natural passive immunity: temporary immunity from antibodies from another person. Examples: fetus from mother through placenta or through breast milk
iv. Artificial passive: inject immune antibodies from another person/animal. Examples: snake bite, tetanus, rabies
what are Epitopes
regions of an antigen that stimulate immune response
provide the name and function of antibody classes
a. IgA class: in plasma, mucus, saliva, tears, intestinal secretions and breast milk. Immunity to newborns
b. IgD class: B cell activation by antigens
c. IgE class: stimulates eosinophils against parasites
d. IgG class: main antibody in secondary immune response;
e. IgM class: main antibody in primary immune response. Plasma and lymph
What are the 2 types of adaptive immunity
Humoral/ antibody-mediated immunity (B cells)
Cellular/ cell-mediated immunity (T cells)
What are the 2 tests that T cells have to pass to be considered immunocompetent
i. Positive selection: cells are tested to ensures that T cells will respond to foreign antigens (antigen-MHC complexes)
fail=destroyed
pass= negative selection
ii. Negative selection: Negative selection ensures that T cells have self tolerance and will not react to self-cells
fail= Clonal deletion, Anergy- self-reactive cells are alive but unresponsive
pass= transported to secondary lymphatic tissue as Naïve lymphocytes
Name the classes of T cells
Cytotoxic T (T_C) cells: carry out attack
Helper T (T_H) cells: Activate T and B cells, and NK cells, nonspecific immune responses
Regulatory T (T_R) cells: limit immune response
Memory T (T_H) cells : memory in cellular immunity
How do Cytotoxic T cells carry out their attack on pathogens
i. Perforin and granzymes: kill cells like NK cells
ii. Interferons: inhibit viral replication
iii. Tumor necrosis factor: kills cancer cells, macrophage activation
explain the steps in responding to a foreign pathogen
APC cells presents foreign antigen on the MHC-1 molecule on its cell surface. Cytotoxic T cells responds to MHC-1=Perforin and granzymes, Interferons, Tumor necrosis factor
Helper T activated by antigen from APC on MHC-2 molecule= attract other WBCs, activate T and B cells.
Some of the cytotoxic and helper T cells become Memory cells for next time
What happens to B or T cells that don’t pass positive and negative selection
Fail Positive select= apoptosis
Fail negative selection= anergy (turned off secret chemical to alert other but cant attack)
