NEET MDS Synopsis
Neurons
PhysiologyNeurons :
Types of neurons based on structure:
a multipolar neuron because it has many poles or processes, the dendrites and the axon. Multipolar neurons are found as motor neurons and interneurons. There are also bipolar neurons with two processes, a dendrite and an axon, and unipolar neurons, which have only one process, classified as an axon.. Unipolar neurons are found as most of the body's sensory neurons. Their dendrites are the exposed branches connected to receptors, the axon carries the action potential in to the central nervous system.
Types of neurons based on function:
motor neurons - these carry a message to a muscle, gland, or other effector. They are said to be efferent, i.e. they carry the message away from the central nervous system.
sensory neurons - these carry a message in to the CNS. They are afferent, i.e. going toward the brain or spinal cord.
interneuron (ie. association neuron, connecting neuron) - these neurons connect one neuron with another. For example in many reflexes interneurons connect the sensory neurons with the motor neurons.
Amelogenesis Imperfecta
PedodonticsClassification of Amelogenesis Imperfecta
Amelogenesis imperfecta (AI) is a group of genetic conditions that affect the
development of enamel, leading to various enamel defects. The classification of
amelogenesis imperfecta is based on the phenotype of the enamel and the mode of
inheritance. Below is a detailed classification of amelogenesis imperfecta.
Type I: Hypoplastic
Hypoplastic amelogenesis imperfecta is characterized by a deficiency in the
amount of enamel produced. The enamel may appear thin, pitted, or smooth,
depending on the specific subtype.
1A: Hypoplastic Pitted
Inheritance: Autosomal dominant
Description: Enamel is pitted and has a rough
surface texture.
1B: Hypoplastic, Local
Inheritance: Autosomal dominant
Description: Localized areas of hypoplasia
affecting specific teeth.
1C: Hypoplastic, Local
Inheritance: Autosomal recessive
Description: Similar to 1B but inherited in an
autosomal recessive manner.
1D: Hypoplastic, Smooth
Inheritance: Autosomal dominant
Description: Enamel appears smooth with a lack of
pits.
1E: Hypoplastic, Smooth
Inheritance: Linked dominant
Description: Similar to 1D but linked to a dominant
gene.
1F: Hypoplastic, Rough
Inheritance: Autosomal dominant
Description: Enamel has a rough texture with
hypoplastic features.
1G: Enamel Agenesis
Inheritance: Autosomal recessive
Description: Complete absence of enamel on affected
teeth.
Type II: Hypomaturation
Hypomaturation amelogenesis imperfecta is characterized by enamel that is
softer and more prone to wear than normal enamel, often with a mottled
appearance.
2A: Hypomaturation, Pigmented
Inheritance: Autosomal recessive
Description: Enamel has a pigmented appearance,
often with brown or yellow discoloration.
2B: Hypomaturation
Inheritance: X-linked recessive
Description: Similar to 2A but inherited through
the X chromosome.
2D: Snow-Capped Teeth
Inheritance: Autosomal dominant
Description: Characterized by a white, snow-capped
appearance on the incisal edges of teeth.
Type III: Hypocalcified
Hypocalcified amelogenesis imperfecta is characterized by enamel that is
poorly mineralized, leading to soft, chalky teeth that are prone to rapid wear
and caries.
3A:
Inheritance: Autosomal dominant
Description: Enamel is poorly calcified, leading to
significant structural weakness.
3B:
Inheritance: Autosomal recessive
Description: Similar to 3A but inherited in an
autosomal recessive manner.
Type IV: Hypomaturation, Hypoplastic with Taurodontism
This type combines features of both hypomaturation and hypoplasia, along with
taurodontism, which is characterized by elongated pulp chambers and short roots.
4A: Hypomaturation-Hypoplastic with Taurodontism
Inheritance: Autosomal dominant
Description: Enamel is both hypoplastic and
hypomature, with associated taurodontism.
4B: Hypoplastic-Hypomaturation with Taurodontism
Inheritance: Autosomal dominant
Description: Similar to 4A but with a focus on
hypoplastic features.
COMPOSITE RESINS -Reaction
Dental Materials
COMPOSITE RESINS
Reaction
Free radical polymerization
Monomers + initiator. + accelerators-+ polymer molecules
Initiators-start polymerization by decomposing and reacting with monomer
Accelerators-speed up initiator decomposition
Amines used for accelerating self –curing systems
Light used for accelerating light-curing systems
Retarders or inhibitors-prevent premature polymerization
Dens in Dente
PedodonticsDens in Dente (Tooth Within a Tooth)
Dens in dente, also known as "tooth within a tooth," is a developmental
dental anomaly characterized by an invagination of the enamel and dentin,
resulting in a tooth structure that resembles a tooth inside another tooth. This
condition can affect both primary and permanent teeth.
Diagnosis
Radiographic Verification:
The diagnosis of dens in dente is confirmed through radiographic
examination. Radiographs will typically show the characteristic
invagination, which may appear as a radiolucent area within the tooth
structure.
Characteristics
Developmental Anomaly:
Dens in dente is described as a lingual invagination of the enamel,
which can lead to various complications, including pulp exposure,
caries, and periapical pathology.
Occurrence:
This condition can occur in both primary and permanent teeth,
although it is most commonly observed in the permanent dentition.
Commonly Affected Teeth
Permanent Maxillary Lateral Incisors:
Dens in dente is most frequently seen in the permanent maxillary
lateral incisors. The presence of deep lingual pits in these teeth
should raise suspicion for this condition.
Unusual Cases:
There have been reports of dens invaginatus occurring in unusual
locations, including:
Mandibular primary canine
Maxillary primary central incisor
Mandibular second primary molar
Genetic Considerations
Inheritance Pattern:
The condition may exhibit an autosomal dominant inheritance pattern,
as evidenced by the occurrence of dens in dente within the same family,
where some members have the condition while others present with deep
lingual pits.
Variable Expressivity and Incomplete Penetrance:
The variability in expression of the condition among family members
suggests that it may have incomplete penetrance, meaning not all
individuals with the genetic predisposition will express the phenotype.
Clinical Implications
Management:
Early diagnosis and management are crucial to prevent complications
associated with dens in dente, such as pulpitis or abscess formation.
Treatment may involve restorative procedures or endodontic therapy,
depending on the severity of the invagination and the health of the
pulp.
Psychosocial Traits and Skills
PedodonticsAge-Related Psychosocial Traits and Skills for 2- to 5-Year-Old Children
Understanding the psychosocial development of children aged 2 to 5 years is
crucial for parents, educators, and healthcare providers. This period is marked
by significant growth in motor skills, social interactions, and language
development. Below is a breakdown of the key traits and skills associated with
each age group within this range.
Two Years
Motor Skills:
Focused on gross motor skills, such as running and jumping.
Sensory Exploration:
Children are eager to see and touch their environment, engaging in
sensory play.
Attachment:
Strong attachment to parents; may exhibit separation anxiety.
Play Behavior:
Tends to play alone and rarely shares toys or space with others
(solitary play).
Language Development:
Limited vocabulary; beginning to form simple sentences.
Self-Help Skills:
Starting to show interest in self-help skills, such as dressing or
feeding themselves.
Three Years
Social Development:
Less egocentric than at two years; begins to show a desire to please
others.
Imagination:
Exhibits a very active imagination; enjoys stories and imaginative
play.
Attachment:
Continues to maintain a close attachment to parents, though may
begin to explore social interactions with peers.
Four Years
Power Dynamics:
Children may try to impose their will or power over others, testing
boundaries.
Social Interaction:
Participates in small social groups; begins to engage in parallel
play (playing alongside peers without direct interaction).
Expansive Period:
Reaches out to others; shows an interest in making friends and
socializing.
Independence:
Demonstrates many independent self-help skills, such as dressing and
personal hygiene.
Politeness:
Begins to understand and use polite expressions like "thank you" and
"please."
Five Years
Consolidation:
Undergoes a period of consolidation, where skills and behaviors
become more deliberate and refined.
Pride in Possessions:
Takes pride in personal belongings and may show attachment to
specific items.
Relinquishing Comfort Objects:
Begins to relinquish comfort objects, such as a blanket or
thumb-sucking, as they gain confidence.
Cooperative Play:
Engages in cooperative play with peers, sharing and taking turns,
which reflects improved social skills and emotional regulation.
Neutropenia
General Pathology
Neutropenia: Neutropenia is an abnormally low number of neutrophils
Causes
-Typhoid, paratyphoid. .
-Viral and ricketseal infections.
-Malaria, Kala azar.
-Hypersplenism.
-Aplastic and megaloblastic anaemia.
-Marrow infiltration by malignancies, lymphomas etc.
-SLE.
The Laryngopharynx
AnatomyThe Laryngopharynx
The laryngeal part of the pharynx lies posterior to the larynx.
It extends from the superior border of the epiglottis to the inferior border of the cricoid cartilage, where it narrows to become continuous with the oesophagus.
Posteriorly, the laryngopharynx is related to the bodies of C4 to C6 vertebrae.
Its posterior and lateral walls are formed by the middle and inferior constrictor muscles, with the palatopharyngeus and stylopharyngeus internally.
The laryngopharynx communicates with the larynx through the aditus or inlet of the larynx.
The piriform recess is a small, pear-shaped depression of the laryngopharyngeal cavity on each side of the inlet of the larynx.
Regulation of Blood Pressure by Hormones
Physiology
Regulation of Blood Pressure by Hormones
The Kidney
One of the functions of the kidney is to monitor blood pressure and take corrective action if it should drop. The kidney does this by secreting the proteolytic enzyme renin.
Renin acts on angiotensinogen, a plasma peptide, splitting off a fragment containing 10 amino acids called angiotensin I.
angiotensin I is cleaved by a peptidase secreted by blood vessels called angiotensin converting enzyme (ACE) — producing angiotensin II, which contains 8 amino acids.
angiotensin II
constricts the walls of arterioles closing down capillary beds;
stimulates the proximal tubules in the kidney to reabsorb sodium ions;
stimulates the adrenal cortex to release aldosterone. Aldosterone causes the kidneys to reclaim still more sodium and thus water.
increases the strength of the heartbeat;
stimulates the pituitary to release the antidiuretic hormone (ADH, also known as arginine vasopressin).
All of these actions, which are mediated by its binding to G-protein-coupled receptors on the target cells, lead to an increase in blood pressure.