Question

Create a concept map of how the immune system protects the body against an extracellular bacterial infection. Please include sufficient detail of responses from both the innate and adaptive immune responses.

Answer 1

Immunity is the resistance to disease in specific any infectious disease. Innate immunity, also known as natural immunity is present in healthy individuals and block the entry of microbes and also elimination of microbes. Adaptive immunity, also called specific immunity or acquired immunity use lymphocytes in response to microbes for effective defense.

STEPS	INNATE IMMUNITY AND RESPONSES	ACQUIRED IMMUNITY AND RESPONSES
Step 1	First line of Defence by epithelial barriers / cells	Adaptive immune system has 2 types of cells- T cell(cell mediated) and B cells (humoral immunity.) First line of defence is provided by antibodies which stop the microbes at the mucosal membrane and blood and stop them from gaining access to connective tissue.
Step 2	If microbes cross epithelial barrier they are attacked by phagocytes and natural killer cells, plasma proteins and proteins of complement system Phagocytes, including neutrophils and macrophages, ingest microbes into vesicles and destroy them by producing microbicidal substances in these vesicles	If the microbes enter within the cell, B cells cannot function. Defense against intracellular microbes is carried by T lymphocytes.
Step 3	Enhance adaptive immune responses against the microbes	T lymphocytes activate phagocytes to destroy microbes that have been ingested by the phagocytes into intracellular vesicles.
Recognition	By the structures of microbes based on the cell wall composition	Express receptors that recognize wide range of molecules of microbes
Features	non -specific, no memory, non diverse	Specific, Memory, diverse, Non reactivity to self
Display/Presentation of microbes	The entry of microbes -the skin, gastrointestinal tract, and respiratory tract contain specialized antigen-presenting cells (APCs) located in the epithelium that capture antigens, transport them to peripheral lymphoid tissues, and display them to lymphocytes.	Naive T cells recognize the peptide-MHC complexes on the APCs which is the first step in the initiation of T cell responses. Protein antigens also are recognized by B lymphocytes in the lymphoid follicles of the peripheral lymphoid organs
Processing of microbes	Dendritic cells capture protein antigens of microbes entering through the epithelia and transport the antigens to regional lymph nodes, where the antigen-bearing dendritic cells display portions of the antigens for recognition by T lymphocytes.	In the lymph node, if a T cell specifically recognizes an antigen on a dendritic cell, that T cell forms stable conjugates with the dendritic cell and is activated and get proliferated and differentiated. B lymphocytes that recognize and respond to antigen in lymph node follicles differentiate into antibody-secreting cells, which either remain in the lymph nodes or migrate to the bone marrow Protein antigens of microbes are recognized by T cells, carbohydrate, peptidoglycan, complex structures are recognized by B cells.
EFFECTOR CELLS	In innate immunity, macrophages and some granulocytes directly recognize microbes and eliminate them	The effector cells that are generated upon T cell activation preferentially migrate into the tissues infected by microbes, where the T lymphocytes perform their function of eradicating the infection.
REACTIONS	Inflammation induced by cytokines serves to bring leukocytes and plasma proteins to the site of infection or injury, and antiviral defense, which is mediated by type I interferons and Natural Killer cells.	Phagocytosis (antibodies)and Cytotoxicity( T cells)
ELIMINATION	Innate immunity is the early line of defense, mediated by cells and molecules that are always present and ready to eliminate infectious microbes. If not, it is done by adaptive immunity	Effector T lymphocytes migrate to peripheral sites of infection, where they function to eliminate infectious microbes. Plasma cells remain in lymphoid organs and the bone marrow, where they secrete antibodies that enter the circulation and find and eliminate microbes.