Hi guys, Welcome to the Advanced Video Search Engine, and you are watching The Immune System: B and T Cells | A-level Biology | OCR, AQA, Edexcel. That video is uploaded by SnapRevise at 2019-05-22T10:13:01-07:00. We are promoting this video only for entertainment and educational purpose only. So, I hope you like & enjoy it. [2XE0ggUWdYY]
| Name | The Immune System: B and T Cells | A-level Biology | OCR, AQA, Edexcel |
| Video Uploader | Video From SnapRevise |
| Upload Date | This Video Uploaded At 22-05-2019 17:13:01 |
| Video Discription | The Immune System: B and T Cells in a Snap! Unlock the full A-level Biology course at http://bit.ly/2VPykDP created by Adam Tildesley, Biology expert at SnapRevise and graduate of Cambridge University. SnapRevise is the UK’s leading A-level and GCSE revision & exam preparation resource offering comprehensive video courses created by A* Oxbridge tutors. Our courses are designed around the OCR, AQA, SNAB, Edexcel B, WJEC, CIE and IAL exam boards, concisely covering all the important concepts required by each specification. In addition to all the content videos, our courses include hundreds of exam question videos, where we show you how to tackle questions and walk you through step by step how to score full marks. Sign up today and together, let’s make A-level Biology a walk in the park! The Role of T and B Lymphocytes B lymphocytes are responsible for producing antibodies which are protein molecules that are specific to an antigen. Antibodies can bind to their specific antigen and neutralise it. Antibodies are present in the plasma and can bind to specific antigens free in bodily fluids or antigens on cells. We say B lymphocytes are involved in ‘humoral immunity’ -the antibodies are present in bodily fluids, which is also known as ‘humour’. T lymphocytes have specific receptors on their plasma membranes which are specific to antigens. T lymphocyte receptors can only bind directly to antigens present on a body cell. Therefore T lymphocytes are described to be involved in cell-mediated immunity. The Cellular Response of Lymphocytes There are millions of lymphocytes with different receptors which are specific for different pathogenic antigens. The lymphocyte with the correct receptor has to be found and activated when a specific pathogen invades the body. The receptor on a lymphocyte is complementary to the shape of the specific antigen. This contact and subsequent activation is called clonal selection. The contact between the lymphocyte receptor and antigen can be achieved either directly or indirectly. Direct contact happens when the lymphocyte comes across pathogenic cells in the lymph nodes. Indirect contact happens when the lymphocyte comes across an antigen presenting cell which phagocytosed the pathogen. Other immune cells like macrophages then secrete a type of cell signalling molecule called interleukins. These interleukins bind specifically to the selected lymphocyte and cause it to divide by mitosis to produce lots of clones. This increase in the number of cells by mitotic division is called clonal expansion. This whole process of selecting and expanding the correct lymphocyte takes a long time and is slow. Summary Neutrophils, monocytes and macrophages are non-specific immune cells T and B lymphocytes are specific immune cells so they only produce a response against certain infections Lymphocytes provide long term protection against specific pathogens B lymphocytes make antibodies and are involved in the humoral response T lymphocytes bind to antigens on antigen-presenting cells and are involved in the cell mediated response To produce a response, lymphocytes must first undergo clonal selection where the correct specific lymphocyte is found They then undergo clonal expansion where the chosen lymphocyte increases in number 2XE0ggUWdYY |
| Category | Education |
| Tags | snaprevise | a-level | alevel | biology | alevel biology | ocr | aqa | snab | edexcel b | wjec | eduqas | ial | cie | The Immune System: B and T Cells | The Role of B and T Lymphocytes | The Cellular Response of Lymphocytes |
