NEET MDS Synopsis
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.
Lupus erythematosus
General Pathology
Lupus erythematosus
- chronic discoid lupus is primarily limited to the skin, while SLE can involve the skin and other systems.
- pathogenesis: light and other external agents plus deposition of DNA (planted antigen) and immune complexes in the basement membrane.
Histology:
- basal cells along the dermal-epidermal junction and hair shafts (reason for alopecia) are vacuolated (liquefactive degeneration)
- thickening of lamina densa as a reaction to injury.
- immunofluorescent studies reveal a band of immunofluorescence (band test) in involved skin of chronic discoid lupus or involved/uninvolved skin of SLE.
- lymphocytic infiltrate at the dermal-epidermal junction and papillary dermis.
Oxygen Transport in Blood
PhysiologyOxygen Transport in Blood: Hemoglobin
A. Association & Dissociation of Oxygen + Hemoglobin
1. oxyhemoglobin (HbO2) - oxygen molecule bound
2. deoxyhemoglobin (HHb) - oxygen unbound
H-Hb + O2 <= === => HbO2 + H+
3. binding gets more efficient as each O2 binds
4. release gets easier as each O2 is released
5. Several factors regulate AFFINITY of O2
a. Partial Pressure of O2
b. temperature
c. blood pH (acidity)
d. concentration of “diphosphoglycerate” (DPG)
B. Effects of Partial Pressure of O2
1. oxygen-hemoglobin dissociation curve
a. 104 mm (lungs) - 100% saturation (20 ml/100 ml)
b. 40 mm (tissues) - 75% saturation (15 ml/100 ml)
c. right shift - Decreased Affinity, more O2 unloaded
d. left shift- Increased Affinity, less O2 unloaded
C. Effects of Temperature
1. HIGHER Temperature --> Decreased Affinity (right)
2. LOWER Temperature --> Increased Affinity (left)
D. Effects of pH (Acidity)
1. HIGHER pH --> Increased Affinity (left)
2. LOWER pH --> Decreased Affinity (right) "Bohr Effect"
a. more Carbon Dioxide, lower pH (more H+), more O2 release
E. Effects of Diphosphoglycerate (DPG)
1. DPG - produced by anaerobic processes in RBCs
2. HIGHER DPG > Decreased Affinity (right)
3. thyroxine, testosterone, epinephrine, NE - increase RBC metabolism and DPG production, cause RIGHT shift
F. Oxygen Transport Problems
1. hypoxia - below normal delivery of Oxygen
a. anemic hypoxia - low RBC or hemoglobin
b. stagnant hypoxia - impaired/blocked blood flow
c. hypoxemic hypoxia - poor lung gas exchange
2. carbon monoxide poisoning - CO has greater Affinity than Oxygen or Carbon Dioxide
MCQs Paediatrics 1
Paediatrics
1.cleft palate is best repaired
1) Soon after birth B
2) At one month
3) At 6-8 months
4) Between 12-18 months
Ans 4
Cleft lip repair should be done between 3-6 months of age.
2. Intra-osseous access for drugs and fluid administration is recommended for paediatric group up to the age of
1) <one year
2) <4 yeats
3) <6 years
4) Up to 12 years
Ans. 3
3. Which of the following is a true statement regarding congenital diaphragmatic hernia (CDH)
1) Common on right side
2) Associated with pulmonary hypoplasia
3) Present with recurrent vomiting at birth
4) Baby benefited with bag mask ventilation
Ans. 4
CHD is common on left side by which gastric contents herniate to thoracic cavity , Bag mask ventilation in these babies leads to gastric distension which may further compress the lungs and increase mediastinal shift.
Fermentation
Biochemistry
Anaerobic organisms lack a respiratory chain. They must reoxidize NADH produced in Glycolysis through some other reaction, because NAD+ is needed for the Glyceraldehyde-3-phosphate Dehydrogenase reaction (see above). Usually NADH is reoxidized as pyruvate is converted to a more reduced compound, that may be excreted.
The complete pathway, including Glycolysis and the re-oxidation of NADH, is called fermentation.
For example, Lactate Dehydrogenase catalyzes reduction of the keto group in pyruvate to a hydroxyl, yielding lactate, as NADH is oxidized to NAD+.
Skeletal muscles ferment glucose to lactate during exercise, when aerobic metabolism cannot keep up with energy needs. Lactate released to the blood may be taken up by other tissues, or by muscle after exercise, and converted via the reversible Lactate Dehydrogenase back to pyruvate
Fermentation Pathway, from glucose to lactate (omitting H+):
glucose + 2 ADP + 2 Pi → 2 lactate + 2 ATP
Anaerobic catabolism of glucose yields only 2 “high energy” bonds of ATP.
Surface Preparation for Mechanical Bonding
Conservative DentistrySurface Preparation for Mechanical Bonding
Methods for Producing Surface Roughness
Grinding and Etching: The common methods for creating
surface roughness to enhance mechanical bonding include grinding or etching
the surface.
Grinding: This method produces gross mechanical
roughness but leaves a smear layer of hydroxyapatite crystals and
denatured collagen approximately 1 to 3 µm thick.
Etching: Etching can remove the smear layer and
create a more favorable surface for bonding.
Importance of Surface Preparation
Proper surface preparation is critical for achieving effective
mechanical bonding between dental materials, ensuring the longevity and
success of restorations.
Thiazide diuretics
Pharmacology
Thiazide diuretics
Chlorothiazide, Hydrochlorothiazide
Mechanism(s) of Action
1. Block facilitated Na/Cl co-transport in the early distal tubule. This is a relatively minor Na absorption mechanism and the result is modest diuresis
2. Potassium wasting effect
a. Blood volume reduction leads to increased production of aldosterone
b. Increased distal Na load secondary to diuretic effect
c. a + b = increase Na (to blood) for K (to urine) exchange which produces indirect K wasting
3. Increase distal Ca re-absorption (direct effect)
o causes an increase in plasma calcium.This is unimportant NORMALLY but makes thiazides VERY inappropriate choice for hypercalcemic patients.
4. Anti-diuretic effect in nephrogenic diabetes insipidus patients secondary to depletion of Na and Water.
Toxicity
• Electrolyte imbalance (particularly hypokalemia) ,Agranulocytosis , Allergic reactions
• Hyperuricemia , Thrombocytopenia
Maintenance of Homeostasis
Physiology
Maintenance of Homeostasis
The kidneys maintain the homeostasis of several important internal conditions by controlling the excretion of substances out of the body.
Ions. The kidney can control the excretion of potassium, sodium, calcium, magnesium, phosphate, and chloride ions into urine. In cases where these ions reach a higher than normal concentration, the kidneys can increase their excretion out of the body to return them to a normal level. Conversely, the kidneys can conserve these ions when they are present in lower than normal levels by allowing the ions to be reabsorbed into the blood during filtration. (See more about ions.)
pH. The kidneys monitor and regulate the levels of hydrogen ions (H+) and bicarbonate ions in the blood to control blood pH. H+ ions are produced as a natural byproduct of the metabolism of dietary proteins and accumulate in the blood over time. The kidneys excrete excess H+ ions into urine for elimination from the body. The kidneys also conserve bicarbonate ions, which act as important pH buffers in the blood.
Osmolarity. The cells of the body need to grow in an isotonic environment in order to maintain their fluid and electrolyte balance. The kidneys maintain the body’s osmotic balance by controlling the amount of water that is filtered out of the blood and excreted into urine. When a person consumes a large amount of water, the kidneys reduce their reabsorption of water to allow the excess water to be excreted in urine. This results in the production of dilute, watery urine. In the case of the body being dehydrated, the kidneys reabsorb as much water as possible back into the blood to produce highly concentrated urine full of excreted ions and wastes. The changes in excretion of water are controlled by antidiuretic hormone (ADH). ADH is produced in the hypothalamus and released by the posterior pituitary gland to help the body retain water.
Blood Pressure. The kidneys monitor the body’s blood pressure to help maintain homeostasis. When blood pressure is elevated, the kidneys can help to reduce blood pressure by reducing the volume of blood in the body. The kidneys are able to reduce blood volume by reducing the reabsorption of water into the blood and producing watery, dilute urine. When blood pressure becomes too low, the kidneys can produce the enzyme renin to constrict blood vessels and produce concentrated urine, which allows more water to remain in the blood.