Antibodies | Immunoglobulins | Structure & Function | Part 3 

#antibodies #immunesystem #usmle #drnajeeb #neet #medicalscience #medicallectures
Antibodies | Immunoglobulins | Structure & Function | Part 3
Like this video?
Sign up now on our website at www.DrNajeebLe... to access 800+ Exclusive videos on Basic Medical Sciences & Clinical Medicine. These are premium videos (NOT FROM RU-vid). All these videos come with English subtitles & download options. Sign up now! Get Lifetime Access for a one-time payment of $45 ONLY!
Sign up now on our website at members.drnaje...
---------------------------------------------------------------------------------------------------------------------------
Why sign up for premium membership? Here's why!
Membership Features for premium website members.
1. More than 800+ Medical Lectures.
2. Basic Medical Sciences & Clinical Medicine.
3. Mobile-friendly interface with android and iOS apps.
4. English subtitles and new videos every week.
5. Download option for offline video playback.
6. Fanatic customer support and that's 24/7.
7. Fast video playback option to learn faster.
8. Trusted by over 2M+ students in 190 countries.
---------------------------------------------------------------------------------------------------------------------------
▬▬▬▬▬▬▬▬▬▬ Contents of this video ▬▬▬▬▬▬▬▬▬▬
An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the pathogen, called an antigen. Each tip of the "Y" of an antibody contains a paratope (analogous to a lock) that is specific for one particular epitope (analogous to a key) on an antigen, allowing these two structures to bind together with precision. Using this binding mechanism, an antibody can tag a microbe or an infected cell for attack by other parts of the immune system, or can neutralize it directly (for example, by blocking a part of a virus that is essential for its invasion).
To allow the immune system to recognize millions of different antigens, the antigen-binding sites at both tips of the antibody come in an equally wide variety. In contrast, the remainder of the antibody is relatively constant. It only occurs in a few variants, which define the antibody's class or isotype: IgA, IgD, IgE, IgG, or IgM. The constant region at the trunk of the antibody includes sites involved in interactions with other components of the immune system. The class hence determines the function triggered by an antibody after binding to an antigen, in addition to some structural features. Antibodies from different classes also differ in where they are released in the body and at what stage of an immune response.
Together with B and T cells, antibodies are the most important part of the adaptive immune system. They occur in two forms: attached to a B cell or in soluble form in extracellular fluids such as blood plasma. Initially, antibodies are attached to the surface of a B cell - they are then referred to as B-cell receptors (BCR). After an antigen binds to a BCR, the B cell activates to proliferate and differentiate into either plasma cells, which secrete soluble antibodies with the same paratope, or memory B cells, which survive in the body to enable long-lasting immunity to the antigen. Soluble antibodies are released into the blood and tissue fluids, as well as many secretions. Because these fluids were traditionally known as humors, antibody-mediated immunity is sometimes known as, or considered a part of, humoral immunity. The soluble Y-shaped units can occur individually as monomers, or in complexes of two to five units.
Antibodies are glycoproteins belonging to the immunoglobulin superfamily. The terms antibody and immunoglobulin are often used interchangeably, though the term 'antibody' is sometimes reserved for the secreted, soluble form, i.e. excluding B-cell receptors.
---------------------------------------------------------------------------------------------------------------------------
Join this channel to get access to perks:
Sign up now on our website at members.drnaje...
/ @doctornajeeb
Follow us on Facebook :- / drnajeeb
Follow us on Instagram :- / drnajeeblectures