lesson 17 transcript + study guide Flashcards
lymphatic vessels
Thin-walled vessels with valves that return lymph (fluid) to the bloodstream
lymphatic vessels transport
Lymph, which is excess fluid from tissues
lymphatic nodules
Unencapsulated clusters of lymphatic tissue found under epithelial membranes
lymphatic nodules function
Trap pathogens and activate local immune responses
primary lymphatic organs
Bone marrow (B-cell maturation) and thymus (T-cell maturation).
secondary lymphatic organs
Lymph nodes, spleen, and MALT—sites where lymphocytes encounter antigens
What is innate immunity
A nonspecific, fast-acting immune defense that responds to all pathogens the same way.
What are the 5 signs of inflammation
Redness, heat, swelling, pain, and loss of function.
What is the purpose of inflammation?
To bring immune cells to the infection site and help heal damaged tissue.
What is a fever?
A systemic increase in body temperature caused by cytokines like interleukin-1.
How does a fever help fight infection?
It enhances phagocyte activity and decreases iron levels to slow bacterial growth
What are phagocytes?
White blood cells like macrophages and neutrophils that engulf and digest pathogens
What is adaptive immunity
A specific immune response that recognizes and remembers pathogens
antigen
A foreign substance that triggers an immune response.
antibody
A protein made by B cells that binds to and marks antigens for destruction.
lymphocytes
White blood cells (B-cells and T-cells) central to adaptive immunity.
What is humoral immunity
Antibody-mediated immunity involving B-cells and antibodies in the blood.
What is cell-mediated immunity?
T-cell-based immunity where cytotoxic T-cells kill infected or abnormal cells
nonspecific (innate) resistance to disease
inflammation
fever
phagocytes
specific (adaptive) immunity
antigen
antibodies
lymphocytes
humoral (antibody-mediated) immunity
cellular (cell-mediated) immunity
What is the function of skin in immunity?
Acts as a physical barrier to prevent pathogen entry.
What is the role of mucus membranes in the immune system?
Trap pathogens before they can enter the body.
How does saliva contribute to innate immunity?
Contains enzymes that destroy pathogens.
What is the purpose of the flushing action of tears and urine?
Mechanically remove pathogens from body surfaces.
What does stomach acid do in the immune system
Destroys pathogens with its low pH.
innate (outer barriers to pathogen entry)
skin
mucus membranes
saliva
flushing action of urine/tears
stomach acid
What is the role of macrophages?
Phagocytes that destroy pathogens by engulfing them; can consume many.
neutrophils
Rapid-response phagocytes that engulf and destroy pathogens.(phagocyte)
What is the function of natural killer (NK) cells?
Kill virally infected or tumor cells by inducing apoptosis. (lymphocyte)
monocytes
Precursor cells that migrate to infection sites and become macrophages.(macrophage precursor)
dendritic cells
Present antigens to T-cells; link innate and adaptive immunity. (lymphocyte)
What is the MAC (Membrane Attack Complex)?
Complement protein complex that forms pores in pathogen membranes to kill them.(complement)
innate (blood born)
macrophage
neutrophil
natural killer cells
monocyte
dendritic cell
MAC
adaptive (cellular immunity)
cytotoxic t cells
helper t cells
memory t cells
MHC I (on every body cell)
cytotoxic T cells
Destroy infected cells by recognizing antigens on MHC I proteins. (lymphocyte)
What is the role of helper T cells (Th)?
Coordinate both B and T cells by releasing cytokines; activated via MHC II.(lymphocyte)
memory T cell
Persist after infection to mount faster responses to future invasions.(lymphocyte)
Where is MHC I found and what is its function?
Found on all nucleated cells; presents antigens to cytotoxic T cells. (cell membrane marker)
adaptive (humoral immunity)
plasma b cells
memory b cells
MHC II (only on APCs)
IgM
IgD
IgG
IgA
IgE
Plasma B cells
Secrete antibodies into the blood to neutralize pathogens. (lymphocyte)
Where is MHC II found and what does it do?
Found on antigen-presenting cells (APCs); presents antigens to helper T cells. (cell membrane marker)
Memory B cells
Remain after infection to rapidly respond to future exposures (lymphocyte)
IgM
First antibodies made; form pentamers to clump pathogens. (Antibodies)
IgD
Act as antigen receptors on the surface of B cells. (Antibodies)
IgG
Neutralize pathogens, promote phagocytosis, activate complement; most abundant in blood. (Antibodies)
IgA
In body secretions like saliva, tears, and breast milk. (Antibodies)
IgE
Bind to mast cells and basophils to trigger allergic reactions. (Antibodies)
