In this video, we're going to introduce naive T cells, effector T cells, and memory T cells. And we'll also talk about how these naive T cells can actually become effector and memory T cells. Now it is important to note that before a developed T cell encounters its presented antigen that it's supposed to generate an immune response to, that T cell exists in an inactive form that we refer to as a naive T cell. A naive T cell is a T cell that is inactive because it has not yet encountered a presented antigen. Before the T cell can actually generate an immune response, the naive T cell must become activated. When naive T cells encounter a presented antigen on an antigen-presenting cell such as, for example, a dendritic cell, then that naive T cell can become activated. Activated T cells are capable of doing two things. They're capable of proliferating or multiplying to create more identical clones of itself, and they're also capable of differentiating or changing their phenotype to become a slightly different cell type. When they differentiate to change their phenotype, they can differentiate into either an effector T cell or they could differentiate into a memory T cell. The effector T cells are going to be short-lived cells. These effector T cells that are short-lived, generate an immediate immune response to the first infection upon encountering the antigen for the first time. Now the memory T cells, on the other hand, are long-lived cells that can survive for many years, perhaps even the lifespan of the human being. These memory T cells that are long-lived also remember the antigen. By remembering the antigen, what that means is that they do not respond to the first infection. However, they will generate a very fast response to any future infection, such as a secondary infection. That helps to create a stronger immune response when you are exposed to one of these antigens a second time. We'll get to talk more about these details here as we move forward in our course. It is also important to note that there are two main types of effector T cells and two main types of memory T cells, and those are going to be the cytotoxic and helper T cells. That means that there are effector cytotoxic effector T cells, cytotoxic memory T cells, and there are also helper effector T cells and helper memory T cells. If we take a look at our image down below, we can get a better understanding of all of these T cells. Notice on the left-hand side over here, we're focusing on the cytotoxic T cells. Remember that the cytotoxic T cells have an effector cytotoxic T cell, and there's also memory cytotoxic T cells. Notice that these T cells originally start off in their naive forms. Here we have a naive T cell and recall that the naive T cell is going to be inactive because it has not yet encountered its presented antigen. However, when the naive T cell is introduced to its presented antigen by an antigen presenting cell such as a dendritic cell. This cell over here is our antigen-presenting cell presenting an antigen to this naive T cell. When the naive T cell recognizes a presented antigen, then that can lead to T cell activation, which is what we see right here. This T cell activation will allow the T cell to proliferate, divide, and differentiate into either an effector cytotoxic T cell. So this would be a cytotoxic, an effector cytotoxic T cell being represented right here. Notice that we're showing this cytotoxic T cell somewhat like the grim reaper here because it's going to have some immune responses that are similar to a grim reaper. We'll be able to talk about that later as we move forward in our course. Again, in addition to differentiating into effector cytotoxic T cells, the cytotoxic the activation of the naive cytotoxic T cell could also lead to the differentiation into a memory cytotoxic T cell, which is what we have over here. The memory cytotoxic T cell does not respond to the very first infection. Instead, it's a long-lived cell that is capable of responding faster to future infections. Notice that this memory cytotoxic T cell here is saying I will remember this antigen if we encounter it again in the future. Now over here on the right-hand side, we have an analogous image, but instead of cytotoxic T cells, these are for helper T cells. Again, the helper T cells also have an effector helper T cell and a memory helper T cell. Again, it originally starts off as a naive T cell. But upon recognizing and being presented its antigen by an antigen presenting cell, like a dendritic cell, the naive T cell, which is inactive, can become a helper T cell, which is the effector T cell, and, or it could differentiate into a memory T cell, which again, is going to generate a faster response in future infections. The helper T cell is going to, as its name implies, help activate other components of the immune system. We'll be able to talk more about the actual immune responses of these T cells as we move forward in our course. But for now, this here has concluded our lesson on naive T cells and how these naive T cells can become activated to differentiate into either effector T cells or memory T cells, and how there are also cytotoxic and helper versions of each of these T cells. This here concludes this lesson, and we'll be able to get some practice applying this as we move forward. So I'll see you all in our next video.
Table of contents
- 1. Introduction to Anatomy & Physiology5h 40m
- What is Anatomy & Physiology?20m
- Levels of Organization13m
- Variation in Anatomy & Physiology12m
- Introduction to Organ Systems27m
- Homeostasis9m
- Feedback Loops11m
- Feedback Loops: Negative Feedback19m
- Feedback Loops: Positive Feedback11m
- Anatomical Position7m
- Introduction to Directional Terms3m
- Directional Terms: Up and Down9m
- Directional Terms: Front and Back6m
- Directional Terms: Body Sides12m
- Directional Terms: Limbs6m
- Directional Terms: Depth Within the Body4m
- Introduction to Anatomical Terms for Body Regions3m
- Anatomical Terms for the Head and Neck8m
- Anatomical Terms for the Front of the Trunk8m
- Anatomical Terms for the Back9m
- Anatomical Terms for the Arm and Hand9m
- Anatomical Terms for the Leg and Foot15m
- Review- Using Anatomical Terms and Directions12m
- Abdominopelvic Quadrants and Regions19m
- Anatomical Planes & Sections17m
- Organization of the Body: Body Cavities13m
- Organization of the Body: Serous Membranes14m
- Organization of the Body: Serous Membrane Locations8m
- Organization of the Body: Thoracic Cavity8m
- Organization of the Body: Abdominopelvic Cavity12m
- 2. Cell Chemistry & Cell Components12h 37m
- Atoms- Smallest Unit of Matter57m
- Isotopes39m
- Introduction to Chemical Bonding19m
- Covalent Bonds40m
- Noncovalent Bonds5m
- Ionic Bonding37m
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- Introduction to Water7m
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- Introduction to Biomolecules2m
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- Proteins25m
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- Prokaryotic & Eukaryotic Cells26m
- Introduction to Eukaryotic Organelles16m
- Endomembrane System: Protein Secretion34m
- Endomembrane System: Digestive Organelles15m
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- Introduction to the Cytoskeleton10m
- Cell Junctions8m
- Biological Membranes10m
- Types of Membrane Proteins7m
- Concentration Gradients and Diffusion9m
- Introduction to Membrane Transport14m
- Passive vs. Active Transport13m
- Osmosis33m
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- Endocytosis and Exocytosis15m
- 3. Energy & Cell Processes10h 7m
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- Laws of Thermodynamics15m
- Chemical Reactions9m
- ATP20m
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- Enzyme Binding Factors9m
- Enzyme Inhibition10m
- Introduction to Metabolism8m
- Redox Reactions15m
- Introduction to Cellular Respiration22m
- Types of Phosphorylation11m
- Glycolysis19m
- Pyruvate Oxidation8m
- Krebs Cycle16m
- Electron Transport Chain14m
- Chemiosmosis7m
- Review of Aerobic Cellular Respiration19m
- Fermentation & Anaerobic Respiration23m
- Introduction to Cell Division22m
- Organization of DNA in the Cell17m
- Introduction to the Cell Cycle7m
- Interphase18m
- Phases of Mitosis48m
- Cytokinesis16m
- Cell Cycle Regulation18m
- Review of the Cell Cycle7m
- Cancer13m
- Introduction to DNA Replication22m
- DNA Repair7m
- Central Dogma7m
- Introduction to Transcription20m
- Steps of Transcription19m
- Genetic Code25m
- Introduction to Translation30m
- Steps of Translation23m
- Post-Translational Modification6m
- 4. Tissues & Histology10h 3m
- Introduction to Tissues & Histology16m
- Introduction to Epithelial Tissue24m
- Characteristics of Epithelial Tissue37m
- Structural Naming of Epithelial Tissue19m
- Simple Epithelial Tissues1h 2m
- Stratified Epithelial Tissues55m
- Identifying Types of Epithelial Tissue32m
- Glandular Epithelial Tissue26m
- Introduction to Connective Tissue36m
- Classes of Connective Tissue8m
- Introduction to Connective Tissue Proper40m
- Connective Tissue Proper: Loose Connective Tissue56m
- Connective Tissue Proper: Dense Connective Tissue49m
- Specialized Connective Tissue: Cartilage44m
- Specialized Connective Tissue: Bone12m
- Specialized Connective Tissue: Blood9m
- Introduction to Muscle Tissue7m
- Types of Muscle Tissue45m
- Introduction to Nervous Tissue8m
- Nervous Tissue: The Neuron8m
- 5. Integumentary System2h 20m
- 6. Bones & Skeletal Tissue2h 16m
- An Introduction to Bone and Skeletal Tissue18m
- Gross Anatomy of Bone: Compact and Spongy Bone7m
- Gross Anatomy of Bone: Periosteum and Endosteum11m
- Gross Anatomy of Bone: Bone Marrow8m
- Gross Anatomy of Bone: Short, Flat, and Irregular Bones5m
- Gross Anatomy of Bones - Structure of a Long Bone23m
- Microscopic Anatomy of Bones - Bone Matrix9m
- Microscopic Anatomy of Bones - Bone Cells25m
- Microscopic Anatomy of Bones - The Osteon17m
- Microscopic Anatomy of Bones - Trabeculae9m
- 7. The Skeletal System2h 35m
- 8. Joints2h 17m
- 9. Muscle Tissue2h 33m
- 10. Muscles1h 11m
- 11. Nervous Tissue and Nervous System1h 35m
- 12. The Central Nervous System1h 6m
- 13. The Peripheral Nervous System1h 26m
- Introduction to the Peripheral Nervous System5m
- Organization of Sensory Pathways16m
- Introduction to Sensory Receptors5m
- Sensory Receptor Classification by Modality6m
- Sensory Receptor Classification by Location8m
- Proprioceptors7m
- Adaptation of Sensory Receptors8m
- Introduction to Reflex Arcs13m
- Reflex Arcs15m
- 14. The Autonomic Nervous System1h 38m
- 15. The Special Senses2h 41m
- 16. The Endocrine System2h 48m
- 17. The Blood1h 22m
- 18. The Heart1h 42m
- 19. The Blood Vessels3h 35m
- 20. The Lymphatic System3h 16m
- 21. The Immune System14h 37m
- Introduction to the Immune System10m
- Introduction to Innate Immunity17m
- Introduction to First-Line Defenses5m
- Physical Barriers in First-Line Defenses: Skin13m
- Physical Barriers in First-Line Defenses: Mucous Membrane9m
- First-Line Defenses: Chemical Barriers24m
- First-Line Defenses: Normal Microbiota7m
- Introduction to Cells of the Immune System15m
- Cells of the Immune System: Granulocytes28m
- Cells of the Immune System: Agranulocytes26m
- Introduction to Cell Communication5m
- Cell Communication: Surface Receptors & Adhesion Molecules16m
- Cell Communication: Cytokines27m
- Pattern Recognition Receptors (PRRs)48m
- Introduction to the Complement System24m
- Activation Pathways of the Complement System23m
- Effects of the Complement System23m
- Review of the Complement System13m
- Phagocytosis17m
- Introduction to Inflammation18m
- Steps of the Inflammatory Response28m
- Fever8m
- Interferon Response25m
- Review Map of Innate Immunity
- Introduction to Adaptive Immunity32m
- Antigens12m
- Introduction to T Lymphocytes38m
- Major Histocompatibility Complex Molecules20m
- Activation of T Lymphocytes21m
- Functions of T Lymphocytes25m
- Review of Cytotoxic vs Helper T Cells13m
- Introduction to B Lymphocytes27m
- Antibodies14m
- Classes of Antibodies35m
- Outcomes of Antibody Binding to Antigen15m
- T Dependent & T Independent Antigens21m
- Clonal Selection20m
- Antibody Class Switching17m
- Affinity Maturation14m
- Primary and Secondary Response of Adaptive Immunity21m
- Immune Tolerance28m
- Regulatory T Cells10m
- Natural Killer Cells16m
- Review of Adaptive Immunity25m
- 22. The Respiratory System3h 20m
- 23. The Digestive System2h 5m
- 24. Metabolism and Nutrition4h 0m
- Essential Amino Acids5m
- Lipid Vitamins19m
- Cellular Respiration: Redox Reactions15m
- Introduction to Cellular Respiration22m
- Cellular Respiration: Types of Phosphorylation14m
- Cellular Respiration: Glycolysis19m
- Cellular Respiration: Pyruvate Oxidation8m
- Cellular Respiration: Krebs Cycle16m
- Cellular Respiration: Electron Transport Chain14m
- Cellular Respiration: Chemiosmosis7m
- Review of Aerobic Cellular Respiration18m
- Fermentation & Anaerobic Respiration23m
- Gluconeogenesis16m
- Fatty Acid Oxidation20m
- Amino Acid Oxidation17m
- 25. The Urinary System2h 39m
- 26. Fluid and Electrolyte Balance, Acid Base Balance Coming soon
- 27. The Reproductive System2h 5m
- 28. Human Development1h 21m
- 29. Heredity Coming soon
21. The Immune System
Introduction to T Lymphocytes
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