NEET MDS Shorts
93778
Pathology
Sarcoidosis is a systemic granulomatous disorder of unknown etiology that can
affect any organ in the body. It is characterized by the formation of non-caseating
granulomas, which are clumps of inflammatory cells that cluster together in
response to an unidentified antigen. The lungs and lymph nodes are most commonly
involved. Here's a detailed explanation for each of the options:
1. Dry cough: This is a common symptom of pulmonary sarcoidosis. The cough is
usually persistent and non-productive, meaning it does not bring up mucus or
phlegm. The presence of a dry cough is not contradicted in the statement "All
are true regarding Sarcoidosis except," so this option is not the correct
answer.
2. Exertional dyspnoea: Shortness of breath on exertion can occur in individuals
with pulmonary sarcoidosis due to the inflammation and granuloma formation in
the lungs. This symptom can be a result of the impaired lung function and
decreased lung capacity caused by the disease. Therefore, this is also a true
statement regarding sarcoidosis.
3. Wheezing: Wheezing is a high-pitched whistling sound that occurs during
breathing, typically heard when airways become narrowed or blocked. It can be a
symptom of pulmonary sarcoidosis, particularly if the disease involves the
bronchi and bronchioles, leading to bronchial obstruction and airflow
limitation. However, it is not the primary symptom and may be less common than
the other respiratory symptoms mentioned.
4. Hemoptysis: While hemoptysis, or coughing up blood, is not a hallmark symptom
of sarcoidosis, it can occur in some cases, particularly when the granulomas are
located in the lungs. It is usually mild and self-limited, but severe cases can
lead to significant bleeding. This is a true statement regarding sarcoidosis, as
it is a possible, although less common, respiratory symptom of the disease.
Since all the options (1, 2, and 4) are true regarding Sarcoidosis
12620
Pathology
Sickle cell disease results from mutation, or change, of certain types of hemoglobin chains in red blood cells (the beta hemoglobin chains). When the oxygen concentration in the blood is reduced, the red blood cell assumes the characteristic sickle shape. This causes the red blood cell to be stiff and rigid, and stops the smooth passage of the red blood cells through the narrow blood vessels.
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.
61194
Pathology
Indirect chemical carcinogens differ from direct acting agents in that they
require metabolic activation to exert their carcinogenic effects. This means
that indirect carcinogens must undergo a chemical transformation within the body
before they can damage DNA and induce cancer. Direct acting carcinogens, on the
other hand, can interact directly with DNA without the need for metabolic
conversion. Therefore, the correct answer is:
2. Induce carcinogenicity after chemical transformation
1. Induce carcinogenicity without chemical transformation: This statement is
incorrect for indirect chemical carcinogens. Indirect carcinogens are typically
non-reactive or less reactive in their original form and must undergo metabolic
activation to become DNA-reactive. This metabolic conversion is crucial for
their carcinogenic potential.
2. Induce carcinogenicity after chemical transformation: This is the correct
explanation. Indirect carcinogens require metabolic activation by the body's
enzyme systems, particularly phase I enzymes such as cytochrome P450, to convert
them into electrophilic or reactive intermediates that can interact with DNA.
This activation process can occur in various tissues, often the liver, where
these enzymes are present. The reactive metabolites then form DNA adducts, which
can lead to mutations and ultimately cancer if not repaired properly by the
cell's DNA repair mechanisms.
3. Don’t require metabolic conversion: This statement is incorrect. Indirect
carcinogens do require metabolic conversion to become active carcinogens. It is
the direct acting carcinogens that can interact with DNA without the need for
such activation because they are already electrophilic or reactive in their
original form.
75369
Pathology
The principal chemical mediator of the immediate phase of acute inflammation
is Histamine. Here's a detailed explanation of the options given:
1. Serotonin: While serotonin is a vasoactive substance that can cause blood
vessels to constrict or dilate, it is not the primary mediator of the immediate
phase of acute inflammation. It is mainly associated with the regulation of
mood, appetite, and sleep. In the context of inflammation, it plays a minor role
compared to histamine.
2. Histamine: Histamine is indeed the correct answer. It is a potent chemical
mediator released from mast cells and basophils in response to injury or
antigenic stimulation. Upon release, histamine acts on blood vessels to cause
vasodilation, increased permeability, and increased blood flow to the injured
area, which are hallmark features of the immediate phase of acute inflammation.
This results in the cardinal signs of inflammation: redness (rubor), heat
(calor), swelling (tumor), and pain (dolor).
3. Kinin-Kallikrein system: The kinin-kallikrein system is another important
mediator of inflammation, but it is more involved in the later phases. When
activated, it results in the formation of kinins, such as bradykinin, which
contribute to increased vascular permeability and pain. However, it is not the
first line mediator in the immediate phase.
4. Complement system: The complement system is a group of proteins in the blood
that work with antibodies to destroy pathogens and trigger inflammation. It is a
key component of the innate immune response, but its activation and role are
more pronounced in the later stages of inflammation rather than the immediate
phase. The complement system is involved in the opsonization of pathogens,
recruitment of phagocytes, and the formation of the membrane attack complex,
which can lyse certain bacteria and cells.
The immediate phase of acute inflammation is characterized by the rapid response
to tissue injury, which includes vasoactive changes and increased vascular
permeability to allow fluid, cells, and proteins to move into the interstitial
space. Histamine is quickly released from mast cells and basophils and acts on
H1 receptors of blood vessels to induce vasodilation and increased permeability.
This leads to the early symptoms of inflammation, such as swelling, redness,
heat, and pain, and is crucial for the initiation of the inflammatory response
to protect the body from harm.
14653
Pathology
Extensive cellulitis is most accurately described by the term "phlegmon Phlegm is a thick, viscous substance produced by the respiratory tract,
especially during a respiratory infection, which can be coughed up from the
lungs or expelled from the nose. It is primarily composed of mucus, dead cells,
and other substances. Phlegmon is a term that is closely related to extensive cellulitis. It refers
to a severe form of cellulitis where the infection has spread deeply into the
subcutaneous tissues and is accompanied by significant inflammation, including
the presence of pus and necrosis. Phlegmon is characterized by intense pain,
swelling, redness, and warmth in the affected area. This condition often
requires aggressive medical management, including intravenous antibiotics and
surgical drainage if an abscess forms. It is an advanced and severe stage of
cellulitis that can lead to systemic infection if not treated properly.
99723
PathologyDiapedesis is a critical process in the body's immune response, particularly in the context of inflammation.
46594
PathologyEpitheloid cells are a hallmark of granulomatous inflammation, which occurs in response to certain chronic infections (like tuberculosis), autoimmune diseases, and foreign body reactions. In granulomas, epitheloid cells aggregate to form a protective wall around the irritant.
73857
Pathology
After 48 hours of inflammation, the predominant cells are typically monocytes,
which differentiate into macrophages. 1. Neutrophils: Neutrophils are the most abundant type of white blood cells
and are the first to arrive at the site of inflammation. They are the primary
cells that dominate the early stages of acute inflammation, which typically
occurs within the first few hours (around 4-6 hours) after the onset of injury
or infection. Their main function is to phagocytose (engulf and destroy)
microbes and release enzymes and proteins that help to break down and dissolve
damaged tissue. Although they play a crucial role in the early stages, their
numbers tend to decrease after this initial phase, making them less likely to be
the predominant cells after 48 hours.
2. Monocytes: Monocytes are the largest of the white blood cells and are part of
the mononuclear phagocytic system. They are recruited from the bloodstream to
the site of inflammation in response to chemical signals called chemokines.
After approximately 24-48 hours of inflammation, monocytes start to predominate
the scene. These cells differentiate into macrophages once they have infiltrated
the tissue. Macrophages are the "clean-up crew" of the immune system, engaging
in phagocytosis, antigen presentation, and the release of cytokines that help
coordinate the overall inflammatory response. They are crucial for the later
stages of inflammation, which include the removal of debris, repair, and
resolution.
3. Eosinophils: Eosinophils are white blood cells that are involved in the
immune response to parasitic infections and in the pathogenesis of certain
allergic diseases. They are not typically the predominant cells in the general
inflammatory response and are more commonly associated with allergic
inflammation and parasitic infections. After 48 hours, eosinophils are less
likely to be the main cell type unless the inflammation is of an allergic or
parasitic nature, in which case they might be present in larger numbers.
However, in a typical non-specific inflammatory process, they are not the
predominant cell type after this duration.
4. Lymphocytes: Lymphocytes are a type of white blood cell that is essential for
the adaptive immune response. There are two main types: T-lymphocytes and
B-lymphocytes. While they are involved in the later stages of inflammation,
particularly in the adaptive immune response, they are not typically the
predominant cells after 48 hours in a general acute inflammatory setting.
Lymphocytes are more likely to be found in higher numbers during the later
stages of inflammation, particularly during the resolution phase or in chronic
inflammation, when the body is mounting a more specific response to the invading
pathogen.
72984
Pathology
Mcroscopic picture of red blood cells (RBCs) in thalassemia, the following
characteristics are typically observed: