NEET MDS Shorts
11100
Oral PathologyBrachytherapy is a type of internal radiation therapy where a sealed radiation source is placed inside or next to the area requiring treatment. This allows a high dose of radiation to be delivered to a specific area, while limiting exposure to surrounding healthy tissues.
85204
Physiology
The parasympathetic nervous system primarily uses acetylcholine as its neurotransmitter, which acts on muscarinic receptors to produce its characteristic effects on various organs.
97896
PedodonticsThe electronic probing system "Foster-Miller probe" detects CEJ and pocket depth.
59209
OrthodonticsEarnest Klein's classification of habits distinguishes between intentional habits (those that are consciously performed) and non-intentional habits (those that occur unconsciously or without deliberate intention). This classification helps in understanding the nature of habits, particularly in the context of dental and orthodontic practices.
65977
Dental Materials
A primer increases the surface energy of the tooth structure, enhancing the ability of the bonding agent to wet and infiltrate the surface.
64022
Oral Medicine
Nystatin and clotrimazole work by binding to ergosterol in the fungal cell membrane, increasing permeability and allowing the leakage of intracellular components. This leads to the death of the affected fungal cell.
10683
PeriodonticsHerpetic gingivostomatitis is commonly seen in preschool children.
56556
Dental Materials
ZnO is a filler in Gutta Percha, and it improves the strength and flexibility of the material.
77349
ProsthodonticsThe occlusogingival height of guide plane flat surfaces should be 2-4mm. This height provides adequate guidance for insertion and removal while maintaining sufficient tooth structure. Less than 2mm provides inadequate guidance, while more than 4mm requires excessive tooth reduction and may compromise pulpal health.
61993
Pathology
Opsonins are molecules that enhance the phagocytosis of antigens by binding to their surfaces and acting as markers or labels that make them more recognizable to phagocytes.
1. lgG (Fc fragment): Immunoglobulin G (IgG) is the most common antibody isotype
in human serum. It plays a crucial role in the secondary immune response. The Fc
region of IgG is the fragment that interacts with Fc receptors present on the
membrane of phagocytic cells. When an antigen is coated with IgG, the Fc
fragments of these antibodies can bind to the Fc receptors, leading to the
activation of the phagocytic process. This is known as antibody-dependent
phagocytosis, where the antibody acts as an opsonin to facilitate the
recognition and engulfment of the antigen by phagocytic cells.
2. C3b of complement cascade: The complement system is a cascade of proteins
that can be activated in response to an infection or the presence of foreign
substances. C3 is a central protein in this system, and when it is cleaved into
C3a and C3b, the latter can bind directly to antigens. C3b acts as an opsonin by
coating the surface of pathogens. The presence of C3b on a microbial surface
allows it to be recognized by complement receptors on phagocytic cells, such as
macrophages. This interaction enhances the efficiency of phagocytosis, as the
receptors can recognize the bound C3b and engulf the antigen more readily.
3. IgM (Fc fragment) and C5b of complement cascade: While IgM is the first
antibody isotype produced in response to an infection and can also opsonize
antigens, it is less efficient than IgG due to its pentameric structure and
lower affinity for phagocytic receptors. However, it is not as commonly
associated with phagocytosis as IgG. Regarding C5b, it is part of the membrane
attack complex (MAC) and is involved in the direct destruction of pathogens
rather than acting as a classical opsonin that leads to phagocytosis. The MAC
assembles on the surface of the antigen and creates pores, leading to osmotic
lysis and destruction of the cell membrane.