NEET MDS Synopsis
RELATIVE RADIO SENSITIVITY OF THE TISSUES
Radiology
RELATIVE RADIO SENSITIVITY OF THE TISSUES
Radiosensitive (2500 r or less kills or seriously injures many cells)
Lymphocytes and lymphoblasts
Bone marrow (myeloblastic and erythroblastic cells)
Epithelium
Germ cells (testes and ovary)
Radioresponsive (2500-5000 r kills or seriously injures many cells)
Epithelium of skin and many appendages.
Endothelium of blood vessels
Salivary glands
Growing bone and cartilage.
Conjunctiva, cornea and lens of eye
Collagen and elastic tissue(fibroblasts themselves are resistant)
Radioresistant (over 5000 r are required to kill or injure many cells)
Kidney
Liver
Thyroid
Pancreas
Pituitary
Adrenal and parathyroids
Mature bone and cartilage
Muscle
Brain and other nervous tissue.
The numbers represent the minimum damaging doses; a gray and a sievert represent roughly the same amount of radiation:
• Fetus--2 grays (Gy).
• Bone marrow--2 Gy.
• Ovary--2-3 Gy.
• Testes--5-15 Gy.
• Lens of the eye--5 Gy.
• Child cartilage--10 Gy.
• Adult cartilage--60 Gy.
• Child bone--20 Gy.
• Adult bone--60 Gy.
• Kidney--23 Gy.
• Child muscle--20-30 Gy.
• Adult muscle--100+ Gy.
• Intestines--45-55 Gy.
• Brain--50 Gy.
Alcohols as Antiseptics
Oral and Maxillofacial SurgeryAlcohols as Antiseptics
Ethanol and isopropyl alcohol are commonly
used as antiseptics in various healthcare settings. They possess antibacterial
properties and are effective against a range of microorganisms, although they
have limitations in their effectiveness against certain pathogens.
Mechanism of Action
Antibacterial Activity: Alcohols exhibit antibacterial
activity against both gram-positive and gram-negative bacteria,
including Mycobacterium tuberculosis.
Protein Denaturation: The primary mechanism by which
alcohols exert their antimicrobial effects is through the denaturation
of proteins. This disrupts cellular structures and functions,
leading to cell death.
Effectiveness and Recommendations
Contact Time:
According to Spaulding (1939), for alcohol to achieve maximum
effectiveness, it must remain in contact with the microorganisms for at
least 10 minutes. This extended contact time is crucial
for ensuring adequate antimicrobial action.
Concentration:
Solutions of 70% alcohol are more effective than
higher concentrations (e.g., 90% or 100%). The presence of water in the
70% solution enhances the denaturation process of proteins, as reported
by Lawrence and Block (1968). Water acts as a co-solvent, allowing for
better penetration and interaction with microbial cells.
Nephritic syndrome
General Pathology
Nephritic syndrome
Characterized by inflammatory rupture of the glomerular capillaries, leaking blood into the urinary space.
Classic presentation: poststreptococcal glomerulonephritis. It occurs after a group A, β–hemolytic Streptococcus infection (e.g., strep throat.)
Caused by autoantibodies forming immune complexes in the glomerulus.
Clinical manifestations:
oliguria, hematuria, hypertension, edema, and azotemia (increased concentrations of serum urea nitrogen
and creatine).
Applications of the Henderson-Hasselbalch equation
Biochemistry
Applications of the Henderson-Hasselbalch equation
• Calculate the ratio of CB to WA, if pH is given
• Calculate the pH, if ratio of CB to WA is known
• Calculate the pH of a weak acid solution of known concentration
• Determine the pKa of a WA-CB pair
• Calculate change in pH when strong base is added to a solution of weak acid. This is represented in a titration curve
• Calculate the pI
Autoimmune(acquired) Haemolytic anaemia
General Pathology
Autoimmune(acquired) Haemolytic anaemia
Auto antibodies are usually Ig g type (may be Ig M or Ig A). They may or may not bind complement and may be active in warm or cold temperature They may be complete (agggIutinating) or incomplete. Haemolysis s may be intravascular due to destruction of the antibody coated cells by RE system.
Causes:
a. Idiopathic
b. Secondary to
o Drugs - Methyldopa, Mefanamic acid
o Disease like
-> Infections especially viral.
-> Autoimmune disease especially SLE.
-> Lymphomas and chronic lymphatic leukaemia.
-> Tumours.
Diagnosis : is based on
• Evidences of haemolytic anaemia.
• Demonstration of antibodies
- On red cell surface by direct Coomb’s test
- In serum by indirect Coomb’s test.
Cognitive Theory
PedodonticsCognitive Theory by Jean Piaget (1952)
Overview of Piaget's Cognitive Theory
bb Jean Piaget formulated a comprehensive theory of cognitive development that
explains how children and adolescents think and acquire knowledge. His theories
were derived from direct observations of children, where he engaged them in
questioning about their thought processes. Piaget emphasized that children and
adults actively seek to understand their environment rather than being shaped by
it.
Key Concepts of Piaget's Theory
Piaget's theory of cognitive development is based on the process of
adaptation, which consists of three functional variants:
Assimilation:
This process involves observing, recognizing, and interacting with
an object and relating it to previous experiences or existing categories
in the child's mind. For example, a child who knows what a dog is may
see a cat and initially call it a dog because it has similar features.
Accommodation:
Accommodation occurs when a child changes their existing concepts or
strategies in response to new information that does not fit into their
current schemas. This leads to the development of new schemas. For
instance, after learning that a cat is different from a dog, the child
creates a new category for cats.
Equilibration:
Equilibration refers to the process of balancing assimilation and
accommodation to create stable understanding. When children encounter
new information that challenges their existing knowledge, they adjust
their understanding to achieve a better fit with the facts.
Stages of Cognitive Development
Piaget categorized cognitive development into four major stages:
Sensorimotor Stage (0 to 2 years):
In this stage, infants learn about the world through their senses
and actions. They develop object permanence and begin to understand that
objects continue to exist even when they cannot be seen.
Pre-operational Stage (2 to 6 years):
During this stage, children begin to use language and engage in
symbolic play. However, their thinking is still intuitive and
egocentric, meaning they have difficulty understanding perspectives
other than their own.
Concrete Operational Stage (6 to 12 years):
Children in this stage develop logical thinking but are still
concrete in their reasoning. They can perform operations on tangible
objects and understand concepts such as conservation (the idea that
quantity does not change even when its shape does).
Formal Operational Stage (11 to 15 years):
In this final stage, adolescents develop the ability to think
abstractly and hypothetically. They can formulate and test hypotheses
and engage in systematic planning.
Merits of Piaget’s Theory
Comprehensive Framework: Piaget's theory is one of the
most comprehensive theories of cognitive development, providing a structured
understanding of how children think and learn.
Insight into Learning: The theory suggests that
examining children's incorrect answers can provide valuable insights into
their cognitive processes, just as much as correct answers can.
Demerits of Piaget’s Theory
Underestimation of Abilities: Critics argue that Piaget
underestimated the cognitive abilities of children, particularly in the
pre-operational stage.
Overestimation of Age Differences: The theory may
overestimate the differences in thinking abilities between age groups,
suggesting a more rigid progression than may actually exist.
Vagueness in Change Processes: There is some vagueness
regarding how changes in thinking occur, particularly in the transition
between stages.
Underestimation of Social Environment: Piaget's theory
has been criticized for underestimating the role of social interactions and
cultural influences on cognitive development.
Miscellaneous Non-Neoplastic Diseases - Urticaria
General Pathology
Urticaria (hives) refers to the presence of edema within the dermis and itchy elevations of the skin which may relate to either a Type I (MC) or Type III hypersensitivity reaction.
Type III hypersensitivity reaction.
- exaggerated venular permeability MC related to IgE mediated disease and release of histamine from mast cells.
HISTOLOGY OF THE ODONTOBLAST
Dental Anatomy
HISTOLOGY OF THE ODONTOBLAST
Formation of Dentin
Mantle dentin: First formed dentin
Type I collagen with ground substance
Formation of the odontoblast process
Matrix vesicles
Appearance of hydroxyapatite crystals
Predentin
Primary physiologic (circumpulpal) dentin
All organic matrix is formed from odontoblasts
Smaller collagen fibers
Presence of phosphophoryn
Mineralization
Globular calcification
Interglobular dentin: Areas of incomplete calcification
Incremental lines of von Ebner: Daily, 4mm of organic matrix is deposited. Also every 5 days the arrangement of collagen fibers changes. This creates the incremental lines of von Ebner.
Intratubular dentin
Dentin tubules
S-shaped in the coronal aspect, straight in root dentin
Von Korff fibers
They are an artifact