Week 1 - Pathogens and innate immunity Flashcards
overall functions of the immune system
- destroy pathogen
- detect and kill abnormal cells
- remove cell debris from the body
basic steps in immune response
- Detect and identify pathogen
- communicate with other immune cells
- recruit and coordinate response among all participants
- destroy or suppress pathogen
how do viruses replicate
A virus needs a cell to replicate
it contains DNA/RNA in its core
1. viral DNA/RNA undergoes replication
2. viral DNA also undergoes transcription and then translation to give capsid proteins
3. self-assembly of all diff components and virus particles exit cell
types of immune responses
innate immunity and adaptive/acquired immunity
innate immunity
rapid, non-specific
adaptive immunity
slow, specific
components of immune system
primary and secondary lymphoid tissue
primary lymphoid tissue
thymus (produces T lymphocytes), bone marrow (produces most blood cells), lymphatic vessels
secondary lymphoid tissues
diffuse lymphoid tissues (tonsils, skin MALT)
encapsulated lymphoid tissues (spleen and lymph nodes)
lymphatics
- transport excess tissue fluid (~3L) to blood
- transport pathogens/dendritic cells to lymph nodes
- transport fat from digestive system to blood
specialized lymphoid organs
lymph nodes (monitor lymph) and spleen (monitors blood)
spleen - structure
red pulp- blood vessels and macrophages
white pulp- lymphocytes
what can lymphocytes differentiate into
T lymphocytes
B lymphocytes
natural killer cells
innate lymphoid cells
functions of lymphocytes
required for both adaptive (T cells and B cells ) and innate (natural killer cells) immunity
functions of monocytes
migrate into tissue and become macrophages. phagocytes and present antigens.
neutrophils
circulate in the blood and migrate into tissues. Phgocytes.
eosinophils
found in digestive tract, lungs, urinary and genital epithelia, and defend against parasites. also participate in allergic reactions.
basophils and mast cells
release chemicals that contribute to inflammation and innate immune response
dendritic cells
found in skins and other organs. present antigens.
physical barriers in the innate immune system
epithelium - the protective barrier of the skin and mucous membranes is the body’s first line of defense
glandular secretions - mucus, antibodies, enzymes to trap and disable pathogens
stomach acidity - the low pH of the stomach helps destroy swallowed pathogens
mechanical removal - pathogens can be physically removed through mucocilliary escalator, tears, coughing, sneezing and GI motility.
what do phagocytes - macrophages and neutrophils do (also dendritic cells)
they recognize pathogens and sites of injury via pattern-recognition receptors that bind to pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs)
neutrophils also act by releasing granules and by forming neutrophil extracellular traps (NETs) - the chromatin in DNA helps form these
how do the phagocytes work - process
- epithelial cells start to express adhesion molecules that bind to the neutrophils
- diapedesis (extravasation) neutrophils must sneak out of capillaries - out of bloodstream and into the tissue
- neutrophils and phagocytes attracted to pathogen by chemotaxis
- phagocytosis and pathogen engulfed
what are the chemotaxins
PAMPs (eg. bacterial toxins + cell wall components) and DAMPs (eg. DNA), cytokines, etc
opsonin
substance that coats pathogen, increasing likelihood of phagocytosis
