NEET MDS Synopsis
Sedative-Hypnotic and Anxiolytic Drugs
Pharmacology
Sedative-Hypnotic Drugs
Sedative drug is the drug that reduce anxiety (anxiolytic) and produce sedation and referred to as minor tranquillisers.
Hypnotic drug is the drug that induce sleep
Effects: make you sleepy; general CNS depressants
Uses: sedative-hypnotic (insomnia ), anxiolytic (anxiety, panic, obsessive compulsive, phobias), muscle relaxant (spasticity, dystonias), anticonvulsant (absence, status epilepticus, generalized seizures—rapid tolerance develops), others (pre-operative medication and endoscopic procedures, withdrawal from chronic use of ethanol or other CNS depressants)
1- For panic disorder alprazolam is effective.
2- muscle disorder: (reduction of muscle tone and coordination) diazepam is useful in treatment of skeletal muscle spasm e.g. muscle strain and spasticity of degenerative muscle diseases.
3-epilepsy: by increasing seizure threshold.
Clonazepam is useful in chronic treatment of epilepsy while diazepam is drug of choice in status epilepticus.
4-sleep disorder: Three BDZs are effective hypnotic agents; long acting flurazepam, intermediate acting temazepam and short
acting triazolam. They decrease the time taken to get to sleep They increase the total duration of sleep
5-control of alcohol withdrawals symptoms include diazepam, chlordiazepoxide, clorazepate and oxazepam.
6-in anesthesia: as preanesthetic amnesic agent (also in cardioversion) and as a component of balanced anesthesia
Flurazepam significantly reduce both sleep induction time and numbers of awakenings and increase duration of sleep and little rebound insomnia. It may cause daytime sedation.
Temazepam useful in patients who experience frequent awakening, peak sedative effect occur 2-3 hr. after an oral dose.
Triazolam used to induce sleep in recurring insomnia and in individuals have difficulty in going to sleep, tolerance develop within few days and withdrawals result in rebound insomnia therefore the drug used intermittently.
Drugs and their actions
1. Benzodiazepines: enhance the effect of gamma aminobutyric acid (GABA) at GABA receptors on chloride channels. This increases chloride channel conductance in the brain (GABA A A receptors are ion channel receptors).
2. Barbiturates: enhance the effect of GABA on the chloride channel but also increase chloride channel conductance independently of GABA, especially at high doses
3. Zolpidem and zaleplon: work in a similar manner to benzodiazepines but do so only at the benzodiazepine (BZ1) receptor type. (Both BZ1and BZ2 are located on chloride channels.)
4. Chloral hydrate: probably similar action to barbiturates.
5. Buspirone: partial agonist at a specific serotonin receptor (5-HT1A).
6. Other sedatives (e.g., mephenesin, meprobamate, methocarbamol, carisoprodol, cyclobenzaprine):
mechanisms not well-described. Several mechanisms may be involved.
7. Baclofen: stimulates GABA linked to the G protein, Gi , resulting in an increase in K + conductance and a decrease in Ca2+ conductance. (Other drugs mentioned above do not bind to the GABA B receptor.)
8. Antihistamines (e.g., diphenhydramine): block H1 histamine receptors. Doing so in the CNS leads to sedation.
9. Ethyl alcohol: its several actions include a likely effect on the chloride channel.
Tracheostomy
General SurgeryTracheostomy
Tracheostomy is a surgical procedure that involves creating an opening in the
trachea (windpipe) to facilitate breathing. This procedure is typically
performed when there is a need for prolonged airway access, especially in cases
where the upper airway is obstructed or compromised. The incision is usually
made between the 2nd and 4th tracheal rings, as entry through the 1st ring can
lead to complications such as tracheal stenosis.
Indications
Tracheostomy may be indicated in various clinical scenarios, including:
Acute Upper Airway Obstruction: Conditions such as
severe allergic reactions, infections (e.g., epiglottitis), or trauma that
obstruct the airway.
Major Surgery: Procedures involving the mouth, pharynx,
or larynx that may compromise the airway.
Prolonged Mechanical Ventilation: Patients requiring
artificial ventilation for an extended period, such as those with
respiratory failure.
Unconscious Patients: Situations involving head
injuries, tetanus, or bulbar poliomyelitis where airway protection is
necessary.
Procedure
Technique
Incision: A horizontal incision is made in the skin
over the trachea, typically between the 2nd and 4th tracheal rings.
Dissection: The subcutaneous tissue and muscles are
dissected to expose the trachea.
Tracheal Entry: An incision is made in the trachea, and
a tracheostomy tube is inserted to maintain the airway.
Complications of Tracheostomy
Tracheostomy can be associated with several complications, which can be
categorized into intraoperative, early postoperative, and late postoperative
complications.
1. Intraoperative Complications
Hemorrhage: Bleeding can occur during the procedure,
particularly if major blood vessels are inadvertently injured.
Injury to Paratracheal Structures:
Carotid Artery: Injury can lead to significant
hemorrhage and potential airway compromise.
Recurrent Laryngeal Nerve: Damage can result in
vocal cord paralysis and hoarseness.
Esophagus: Injury can lead to tracheoesophageal
fistula formation.
Trachea: Improper technique can cause tracheal
injury.
2. Early Postoperative Complications
Apnea: Temporary cessation of breathing may occur,
especially in patients with pre-existing respiratory issues.
Hemorrhage: Postoperative bleeding can occur, requiring
surgical intervention.
Subcutaneous Emphysema: Air can escape into the
subcutaneous tissue, leading to swelling and discomfort.
Pneumomediastinum and Pneumothorax: Air can enter the
mediastinum or pleural space, leading to respiratory distress.
Infection: Risk of infection at the incision site or
within the tracheostomy tube.
3. Late Postoperative Complications
Difficult Decannulation: Challenges in removing the
tracheostomy tube due to airway swelling or other factors.
Tracheocutaneous Fistula: An abnormal connection
between the trachea and the skin, which may require surgical repair.
Tracheoesophageal Fistula: An abnormal connection
between the trachea and esophagus, leading to aspiration and feeding
difficulties.
Tracheoinnominate Arterial Fistula: A rare but
life-threatening complication where the trachea erodes into the innominate
artery, resulting in severe hemorrhage.
Tracheal Stenosis: Narrowing of the trachea due to scar
tissue formation, which can lead to breathing difficulties.
Hyoid Bone
Anatomy
U-shaped bone
Body
Greater horn
Lesser horn
Suspended by ligaments from the styloid process
Maternal Attitudes and Child Behaviors
PedodonticsMaternal Attitudes and Corresponding Child Behaviors
Overprotective:
Mother's Behavior: A mother who is overly
protective tends to shield her child from potential harm or discomfort,
often to the point of being controlling.
Child's Behavior: Children raised in an
overprotective environment may become shy, submissive, and anxious. They
may struggle with independence and exhibit fearfulness in new situations
due to a lack of opportunities to explore and take risks.
Overindulgent:
Mother's Behavior: An overindulgent mother tends to
give in to the child's demands and desires, often providing excessive
affection and material rewards.
Child's Behavior: This can lead to children who are
aggressive, demanding, and prone to temper tantrums. They may struggle
with boundaries and have difficulty managing frustration when they do
not get their way.
Under-affectionate:
Mother's Behavior: A mother who is
under-affectionate may be emotionally distant or neglectful, providing
little warmth or support.
Child's Behavior: Children in this environment may
be generally well-behaved but can struggle with cooperation. They may be
shy and cry easily, reflecting their emotional needs that are not being
met.
Rejecting:
Mother's Behavior: A rejecting mother may be
dismissive or critical of her child, failing to provide the emotional
support and validation that children need.
Child's Behavior: This can result in children who
are aggressive, overactive, and disobedient. They may act out as a way
to seek attention or express their frustration with the lack of
nurturing.
Authoritarian:
Mother's Behavior: An authoritarian mother enforces
strict rules and expectations, often without providing warmth or
emotional support. Discipline is typically harsh and non-negotiable.
Child's Behavior: Children raised in authoritarian
environments may become evasive and dawdling, as they may fear making
mistakes or facing punishment. They may also struggle with self-esteem
and assertiveness.
Functions of the nervous system
PhysiologyFunctions of the nervous system:
1) Integration of body processes
2) Control of voluntary effectors (skeletal muscles), and mediation of voluntary reflexes.
3) Control of involuntary effectors ( smooth muscle, cardiac muscle, glands) and mediation of autonomic reflexes (heart rate, blood pressure, glandular secretion, etc.)
4) Response to stimuli
5) Responsible for conscious thought and perception, emotions, personality, the mind.
Contractility
Physiology
Contractility : Means ability of cardiac muscle to convert electrical energy of action potential into mechanical energy ( work).
The excitation- contraction coupling of cardiac muscle is similar to that of skeletal muscle , except the lack of motor nerve stimulation.
Cardiac muscle is a self-excited muscle , but the principles of contraction are the same . There are many rules that control the contractility of the cardiac muscles, which are:
1. All or none rule: due to the syncytial nature of the cardiac muscle.There are atrial syncytium and ventricular syncytium . This rule makes the heart an efficient pump.
2. Staircase phenomenon : means gradual increase in muscle contraction following rapidly repeated stimulation..
3. Starling`s law of the heart: The greater the initial length of cardiac muscle fiber , the greater the force of contraction. The initial length is determined by the degree of diastolic filling .The pericardium prevents overstretching of heart , and allows optimal increase in diastolic volume.
Thankful to this law , the heart is able to pump any amount of blood that it receives. But overstretching of cardiac muscle fibers may cause heart failure.
Factors affecting contractility ( inotropism)
I. Positive inotropic factors:
1. sympathetic stimulation: by increasing the permeability of sarcolemma to calcium.
2. moderate increase in temperature . This due to increase metabolism to increase ATP , decrease viscosity of myocardial structures, and increasing calcium influx.
3. Catecholamines , thyroid hormone, and glucagon hormones.
4. mild alkalosis
5. digitalis
6. Xanthines ( caffeine and theophylline )
II. Negative inotropic factors:
1. Parasympathetic stimulation : ( limited to atrial contraction)
2. Acidosis
3. Severe alkalosis
4. excessive warming and cooling .
5. Drugs ;like : Quinidine , Procainamide , and barbiturates .
6. Diphtheria and typhoid toxins.
MANDIBULAR THIRD MOLAR
Dental Anatomy
MANDIBULAR THIRD MOLAR
Facial: The crown is often short and has a rounded outline.
Lingual: Similarly, the crown is short and the crown is bulbous.
Proximal: Mesially and distally, this tooth resembles the first and second molars. The crown of the third molar, however, is shorter than either of the other molars
Occlusal: Four or five cusps may be present. Occlusal surface is a same as of the first or second molar, or poorly developed with many accessory grooves. The occlusal outline is often ovoid and the occlusal surface is constricted. Occasionally, the surface has so many grooves that it is described as crenulated--a condition seen in the great apes
Contact Points; The rounded mesial surface has its contact area more cervical than any other lower molar. There is no tooth distal to the third molar..
Roots:-The roots, two in number, are shorter in length and tend to be fused together. they show a distinct distal curve
VIRAL DISEASES -RABIES
General Pathology
VIRAL DISEASES
RABIES (Hydrophobia)
An acute infectious disease of mammals, especially carnivores, characterized by CNS pathology leading to paralysis and death.
Etiology and Epidemiology
Rabies is caused by a neurotropic virus often present in the saliva of rabid animals
Pathology
The virus travels from the site of entry via peripheral nerves to the spinal cord and the brain, where it multiplies; it continues through efferent nerves to the salivary glands and into the saliva.
microscopic examination shows perivascular collections of lymphocytes but little destruction of nerve cells. Intracytoplasmic inclusion bodies (Negri bodies), usually in the cornu Ammonis, are pathognomonic of rabies, but these bodies are not always found.
Sign/Symptoms
In humans, the incubation period varies from 10 days to > 1 yr and averages 30 to 50 days.
Rabies commonly begins with a short period of depression, restlessness, malaise, and fever. Restlessness increases to uncontrollable excitement, with excessive salivation and excruciatingly painful spasms of the laryngeal and pharyngeal muscles. The spasms, which result from reflex irritability of the deglutition and respiration centers, are easily precipitated Hysteria due to fright
Prognosis and Treatment
Death from asphyxia, exhaustion, or general paralysis usually occurs within 3 to 10 days after onset of symptoms