1+2 Intro to immunobiology Flashcards
Define immunity
Resistance to disease with specific reference to infectious diseases
Define immune system
Collection of cells, molecules and tissues/organs that mediate resistance to foreign microbes, bacteria, drugs, pollen etc
What are foreign agents referred to as?
antigens + immunogens
Define self-discrimination
Ability to recognise and respond to molecules that are foreign, yet not respond to molecules that are part of self
What are the two arms of the immune system?
Innate immune system
Acquired immune system
What are the general characteristics of the innate immunity?
- Provides a rapid, generalised, non-specific response
- Occurs within minutes,
- May last hours -> days
- Includes phagocytosis
- Does not include aby
What does innate immunity involve?
- Cells, tissues that are already present in the body at the time of exposure
- Nothing is created for innate immunity
What does acquired immunity involve?
- Specialised response to particular foreign microbe
What are the general characteristics of acquired immunity?
- Develops slowly; days to weeks.
- Two types of response: humoral and cell mediated
- Has memory
- Does include aby
Define immunisation in relation of acquired immunity
Deliberately inducing an acquired response to stimulate immune memory to offer protection from future infection
Define memory
Ability to recall previous contact with a foreign molecule and upon re-contact be able to respond to it with a more rapid + larger response than the initial contact
What are the two sub categories of innate defenses? + examples
- Surface barriers: skin + mucous membrane
2. Internal defenses: phagocytes, NK cells, inflammation
What are the two sub categories of acquired defenses? + examples
- Humoral: b cells
2. Cell mediated: T cells
Describe the structure of antibodies
- Large Y shaped protein, used to recognise + neutralise foreign material
What is an epitope?
- Also known as antigenic determinant
- Part of the foreign material that is recognised by one antibody molecule
- Antibodies bind to specific epitopes
Define specificity
Ability to discriminate between different molecule entities
What is haematopoiesis
- Where all specialised cell types develop from a common pluripotent bone marrow stem cell
Where to T cells mature?
Thymus
Where do B cells mature?
Bone
Where do B and T cells move after maturation?
Lymphoid tissues
What are macrophages referred to in the bone?
Osteoclast
What are macrophages referred to in the liver?
Kupffer cells
What are macrophages referred to in the lungs?
Alveolar macrophages
What are macrophages referred to in the spleen?
Spleenic macrophages
What are macrophages referred to in the peritoneum?
peritoneal macrophages
What are macrophages referred to in the CNS?
Microglial cells
What are the types of granulocytes?
Neutrophil
Eosinophil
Basophil
What are the types of agranulocytes?
Monocyte
Lymphocyte
Describe white blood cells
- Defends against disease
- Makes up <1% of total blood volume
Name the process by which WBCs leave the capillaries
Diapedesis
How are WBCs able to move through tissue spaces?
Via ameboid motion + chemotaxis
Order from most abundance to least abundance of WBCs in peripheral blood
- Neutrophils
- Lymphocytes
- Monocytes
- Eosinophils
- Basophils
What do neutrophils generally respond to?
Bacteria
What do eosinophils generally respond to?
Parasites
What do basophils generally respond to?
Allergies
What do lymphocytes generally respond to?
Viruses
What do monocytes generally respond to?
Everything
Describe neutrophils
- Polymorphonuclear leucocytes
- Short lived phagocytic cells (~12hrs)
- Exit the blood to engage foreign molecules
- First cells during an inflammatory response
- Produce peroxide + superoxide radicles (toxic to microorganisms)
Describe the microscopy of neutrophils
- Granules stain purple (contains hydrolytic enzymes)
- 3-6 lobes in nucleus
- 2x size of RBCs
Describe eosinophils
- Release enzymes to digest parasitic worms
- Role in modulating immune response
- Role in allergies + asthma
Describe the microscopy of eosinophils
- Stain red cytoplasmic granules
- Bi-lobed nucleus
- Granules lysosyme like
Describe the microscopy of basophils
- Rare WBCs
- Nucleus is deep purple
- Large, dark granules containing histamine
What is histamine?
Inflammatory chemical acting as a vasodilator to attract WBCs to inflamed sites
Describe lymphocytes
- Crucial in adaptive immune response
- 3 types: T cells, B cells, NK cells
- Found in lymphoid tissue
Describe the microscopy of lymphocytes
- Large dark purple circular nuclei with thin rim of blue cytoplasm
T lymphocytes
Activate macrophages and act against virally infected cells as well as tumor cells
B lymphocytes
give rise to plasma cells, producing aby
NK cells
- Non phagocytic large granular lymphocytes
- Attack cells that lack self cell surface receptors
- Induce apoptosis in cancer + virus infected cells
- Secretes potent chemicals to enhance inflammatory response in contact with target cells
- forming pores in cell membrane to cause lysis
Describe Monocytes
- Leave circulation and differentiate into macrophages
- Active phagocytic cells; for viruses, infection + intracellular bacterial parasites
- Activate lymphocytes for an immune response - antigen presentation
Describe the microscopy of monocytes
- Abundant pale blue cytoplasm
- Many granules
- Dark purple staining/ kidney shaped nuclei
Macrophages
- Different types when found in different areas of the body
- All are components of reticuloendothelial system (RES)
What are the main functions of RES?
- Phagocytose microbes in the blood
2. Destruction of aged/imperfect cells
Dendritic cells
- From the same precursor cell as monocytes
- Reside in an immature state
- Specialised antigen presenting cells (link between innate and adaptive)
- Found as interdigitating cells of thymus
- Called langerhan cells in the skin
What are the functions of dendritic cells?
- Phagocytise pathogens
- Enter lymphatics to present antigens to T cells inside lymph nodes
What cells are able to phagocytose?
- monocytes
- macrophages
- dendritic cells
What does APC stand for?
- Antigen presenting cells
