Introduction Flashcards
What is vaccination?
- Inoculation of healthy individuals with weakened or attenuated strains of disease causing agents to prevent disease
What is adaptive immunity?
- The production of antibodies in response pathogens as a result of adaptation to infections
- Requires response time
What is innate immunity?
- Nonspecific defense against infections
- Rapid response
ex. Macrophage (wbc) engulfs and digests microorganism
What is an antigen?
- A substance that stimulates antibody generation and is recognized by adaptive immunity
ex. proteins, glycoproteins, polysacs of pathogens, metals, organic chemicals, and drugs
What is the origin of most leukocytes? What is the exception?
- Most come from bone marrow where many develop and mature
- Certain tissue resident macrophages and lymphocytes (microglia of CNS) originate from yolk sac or fetal liver during embryo development
What is the lymphatic system?
- How immune cells travel through peripheral tissue
- Used to drain extracellular fluid and immune cells from tissue and transported as lymph
- lymph drains into the blood stream
What two progenitors can be produced from a multipotent hematopoietic stem cell?
- Common lymphoid progenitor
- B cells, T cells, NK cells
- Adaptive immunity, develops in lymphoidal organs
- Common myeloid progenitor
- All other leukocytes, dendrites, and platelets
- Innate immunity, develop in bone marrow
What are the four disease-causing microorganisms?
- Viruses
- Bacteria and archaea
- Fungi
- Parasites
What is a microbiome?
- Colonies of microbial communities that are found on skin, mucosa, gastrointestinal tract and have a symbyotic relationship with the host
- Parasites can often get through mucosa and harm cells
What is the order of the body’s defenses against pathogens?
- Anatomical barriers: Skin, mucosa, intestine, respiratory epithelium
- Compliment/antimicrobial proteins: Chemical and enzymatic response near epithelial tissue
- Innate immune cells: Macrophages, granulocytes, NK cells
- Adaptive immunity: B cells and T cells
Outline the steps involved in the immune system being activated
-
Inflammatory inducers indicate the presence of a pathogen or tissue damage
- Bact. lipopolysac, ATP, Urate crystals
-
Sensor cells detect signal via receptors and defend or propagate immune response
- Macrophages, Neutrophils, dendritic cells
-
Mediators act on target tissue
- Cytokines, cytotoxicity
- Target tissue produces antimicrobial proteins to kill infected cells
Why does adaptive immunity take longer to respond compared to innate immunity?
- Adaptive immunity takes longer because it involves making B cells and T cells with a specific antigen receptor to target the pathogen. Additionally memory cells ensure prolonged protection if the same pathogen invades
What is hematopoiesis?
- The development of blood cells, Both red and white, from hematopoietic stem cells
- In bone marrow
- T cells then mature in thymus
- Mast cells then mature in peripheral tissue
- Macrophages then mature in tissue
What is a macrophage? What are its functions?
- Leukocyte
- Found in tissue
- Circulates (immature) as monocyte
- Involved in Adaptive and innate
Functions:
- Phagocytosis (ingestion)
- Induce inflammation by releasing mediators o recruit immune cells
- Antigen presentation to activate T cells
- Scavenge, clear old/dead cells and debris
What is a neutrophil? What is its function?
- Leukocyte
- Also called PMNs
- Most common WBC
- First responder to infections + injuries
- Major player in innate
Functions:
- Phagocytosis (main), and granules are released to digest bacteria
- Cytokine signaling (can signal to other immune cells)
What is an Eosinophil? What is its function?
- Leukocyte
- Less abundant than neutrophils
- Granules contain enzymes and toxic proteins
Functions:
- Defend against parasitic infections
- When pathogen is too large to be engulfed it is instead broken down by granules
What are Basophils and Mast cells? What is their function?
Both:
- Leukocyte
- Less abundant than neutrophils
Functions:
- Allergic response
- Defend against parasites via granule secretion
Basophils:
- Circulate in blood
Mast cells:
- Found in peripheral tissue
- Skin, intestines, airway mucosa and they’re early sensors of infection or injury
What are Natural Killer Cells? What is their function?
- Leukocytes
- Share many functions with T cells
- Cytotoxic molecules (release lytic granules)
Functions:
- Recognize and destroy tumor and infected cells
- Determined by activating and inhibiting ligands for NK’s innate receptors
- Tumor cells: ligand expression decreases which NK cells recognize as non-self
What are innate lymphoid cells? What is their function?
- Leukocyte
- In peripheral tissue
Functions:
- Secrete cytokines that regulate immune cells
- Mirror T-cell functions
What are dendritic cells? What is their function?
- Leukocyte
- In tissue
- Bridge b/t innate and adaptive immunity
Functions:
- Activate T-cells
- Phagocytosis (innate immune receptors)
- Control response of innate immune cells
What are T-cells? What is their function?
- Leukocyte
- Mature in Thymus
- Naive T-cell (immature) has not been exposed to antigen
Functions:
- Effector cells
- Helper T-cells (CD4+)
- Activate immune cells
- Express CD4 co-receptor
- Cytotoxic T-cells (CD8+)
- Release cytotoxins to target cells to cause apoptosis and membrane proliferation
- Regulatory T-cells
- Control immune reaction + prevent autoimmunity
- Inhibit T-cells
- Memory cells
- Have memory of receptors which can be used upon reinfection
What is a B-cell? What is its function?
- Leukocyte
- Matures in bone marrow
- Humoral immunity
- Circulation via blood, mucus, tears etc.
- Native B-cells (immature) have not been exposed to antigen
Functions:
- Effector cells
- Plasma cells (produce antibodies)
- Memory B-cells
- Function as antigen presenter
What is an antigen? What is Immunogenicity? What is Antigenicity?
- Any molecule that can specifically to an antibody or generate peptide fragments that are recognized by a T-cell receptor
- Proteins, glycoproteins, polysac, lipids, drugs, metals, chemicals
- Epitope is a region by which an antigen can be recognized by antigen receptors or antibodies
- The ability to induce humoral/cell-mediated immune response
- The ability of an antigen to bind/interact w/ B or T cell receptors
What are the 6 types of antibody function?
- Agglutination - aggregation
- Neutralization
- Opsonization - recognition and phagocytosis of microbes
- Cytotoxicity
- Degranulation
- Compliment activation
What are cytokines?
- Proteins made by a cell to illicit response
- Cell signaling
- Often called interleukins (IL-n)
Identify the different leukocytes.
What are the different types of microbes?
- Bacteria - single celled, prokaryotes
- Viruses - genetic material surrounded by protein coat
- Fungi - single to multicellular, surrounded by protein coat
- Parasites - Protozoans (single cell euk) or helminths (worms)
What are three mechanisms pathogens use to damage tissue?
- Exotoxin production
- Proteins produced inside the pathogenic bacteria and secreted into surrounding
- Endotoxin
- Constitutive elements of bacteria membrane that are released when bacteria die
- Direct cytopathic effect
- Pathogen harms its host cell
What are the two types of bacteria?
- Gram positive (GP)
- One membrane and thick layer of peptidoglycan
- Gram negative (GN)
- Two membranes + thin peptidoglycan layer
- Lipopolysaccharides (LPS) outer membrane
What can bacteria do to spread?
- Release toxin from outside of cells
- Invade the tissue
- Mix of both
Where can extracellular infection come from? Where can intracellular infection come from?
- Respiratory system, Renal system, CNS
- Immune cells, Epithelial cells, Mesenchymal cells
What are the two types of viruses?
Naked:
- Protein coat (Capsid)
- Spike (membrane protein involved in entry to host)
Envelope:
- Additional membrane envelope
Both:
- RNA and DNA contents can be single or double stranded
What are the general steps of viral infection?
What are fungi?
- Eukaryotes
- Unicellular (yeast, budding) or multicellular (molds, asexual spores)
- Most fungi are opportunistic
- Dimorphic fungi are true pathogens
- Can invade extra or intracellularly
What are parasites?
- Protozoans
- Grouped by locomotion
- Intra or extra
- Helminths
- Worms66
- Round, flat, segmented
