NEET MDS Synopsis
Characteristics of Facilitated Diffusion & Active Transport
PhysiologyCharacteristics of Facilitated Diffusion & Active Transport - both require the use of carriers that are specific to particular substances (that is, each type of carrier can 'carry' one type of substance) and both can exhibit saturation (movement across a membrane is limited by number of carriers & the speed with which they move materials
Phospholipids Functions
Biochemistry
- There are two important phospholipids, Phosphatidylcholine and Phosphatidylserine found the cell membrane without which cell cannot function normally.
- Phospholipids are also important for optimal brain health as they found the cell membrane of brain cells also which help them to communicate and influence the receptors function. That is the reason food stuff which is rich in phospholipids like soy, eggs and the brain tissue of animals are good for healthy and smart brain.
- Phospholipids are the main component of cell membrane or plasma membrane. The bilayer of phospholipid molecules determine the transition of minerals, nutrients, and drugs in and out of the cell and affect various functions of them.
- As phospholipids are main component of all cell membrane, they influence a number of organs and tissues, such as the heart, blood cells and the immune system. As we grown up the amount of phospholipids decreases and reaches to decline.
- Phospholipids present in cell membrane provide cell permeability and flexibility with various substances as well its ability to move fluently. The arrangement of phospholipid molecules in lipid bilayer prevent amino acids, carbohydrates, nucleic acids, and proteins from moving across the membrane by diffusion. The lipid bi-layer is usually help to prevent adjacent molecules from sticking to each other.
- The selectivity of cell membrane form certain substances are due to the presence of hydrophobic and hydrophilic part molecules and their arrangement in bilayer. This bilayer is also maintained the normal pH of cell to keeps it functioning properly.
- Phospholipids are also useful in the treatment of memory problem associated with chronic substances as they improve the ability of organism to adapt the chronic stress.
Cryosurgery
Oral and Maxillofacial SurgeryCryosurgery
Cryosurgery is a medical technique that utilizes extreme
rapid cooling to freeze and destroy tissues. This method is particularly
effective for treating various conditions, including malignancies, vascular
tumors, and aggressive tumors such as ameloblastoma. The process involves
applying very low temperatures to induce localized tissue destruction while
minimizing damage to surrounding healthy tissues.
Mechanism of Action
The effects of rapid freezing on tissues include:
Reduction of Intracellular Water:
Rapid cooling causes water within the cells to freeze, leading to a
decrease in intracellular water content.
Cellular and Cell Membrane Shrinkage:
The freezing process results in the shrinkage of cells and their
membranes, contributing to cellular damage.
Increased Concentrations of Intracellular Solutes:
As water is removed from the cells, the concentration of solutes
(such as proteins and electrolytes) increases, which can disrupt
cellular function.
Formation of Ice Crystals:
Both intracellular and extracellular ice crystals form during the
freezing process. The formation of these crystals can puncture cell
membranes and disrupt cellular integrity, leading to cell death.
Cryosurgery Apparatus
The equipment used in cryosurgery typically includes:
Storage Bottles for Pressurized Liquid Gases:
Liquid Nitrogen: Provides extremely low
temperatures of approximately -196°C, making it highly
effective for cryosurgery.
Liquid Carbon Dioxide or Nitrous Oxide: These gases
provide temperatures ranging from -20°C to -90°C, which
can also be used for various applications.
Pressure and Temperature Gauge:
This gauge is essential for monitoring the pressure and temperature
of the cryogenic gases to ensure safe and effective application.
Probe with Tubing:
A specialized probe is used to direct the pressurized gas to the
targeted tissues, allowing for precise application of the freezing
effect.
Treatment Parameters
Time and Temperature: The specific time and temperature
used during cryosurgery depend on the depth and extent of the tumor being
treated. The clinician must carefully assess these factors to achieve
optimal results while minimizing damage to surrounding healthy tissues.
Applications
Cryosurgery is applied in the treatment of various conditions, including:
Malignancies: Used to destroy cancerous tissues in
various organs.
Vascular Tumors: Effective in treating tumors that have
a significant blood supply.
Aggressive Tumors: Such as ameloblastoma, where rapid
and effective tissue destruction is necessary.
Management and Treatment of Le Fort Fractures
Oral and Maxillofacial SurgeryManagement and Treatment of Le Fort Fractures
Le Fort fractures require careful assessment and management to restore facial
anatomy, function, and aesthetics. The treatment approach may vary depending on
the type and severity of the fracture.
Le Fort I Fracture
Initial Assessment:
Airway Management: Ensure the airway is patent,
especially if there is significant swelling or potential for airway
compromise.
Neurological Assessment: Evaluate for any signs of
neurological injury.
Treatment:
Non-Surgical Management:
Observation: In cases of non-displaced fractures,
close monitoring may be sufficient.
Pain Management: Analgesics to manage pain.
Surgical Management:
Open Reduction and Internal Fixation (ORIF):
Indicated for displaced fractures to restore occlusion and facial
symmetry.
Maxillomandibular Fixation (MMF): May be used
temporarily to stabilize the fracture during healing.
Postoperative Care:
Follow-Up: Regular follow-up to monitor healing and
occlusion.
Oral Hygiene: Emphasize the importance of
maintaining oral hygiene to prevent infection.
Le Fort II Fracture
Initial Assessment:
Airway Management: Critical due to potential airway
compromise.
Neurological Assessment: Evaluate for any signs of
neurological injury.
Treatment:
Non-Surgical Management:
Observation: For non-displaced fractures, close
monitoring may be sufficient.
Pain Management: Analgesics to manage pain.
Surgical Management:
Open Reduction and Internal Fixation (ORIF):
Required for displaced fractures to restore occlusion and facial
symmetry.
Maxillomandibular Fixation (MMF): May be used to
stabilize the fracture during healing.
Postoperative Care:
Follow-Up: Regular follow-up to monitor healing and
occlusion.
Oral Hygiene: Emphasize the importance of
maintaining oral hygiene to prevent infection.
Le Fort III Fracture
Initial Assessment:
Airway Management: Critical due to potential airway
compromise and significant facial swelling.
Neurological Assessment: Evaluate for any signs of
neurological injury.
Treatment:
Non-Surgical Management:
Observation: In cases of non-displaced fractures,
close monitoring may be sufficient.
Pain Management: Analgesics to manage pain.
Surgical Management:
Open Reduction and Internal Fixation (ORIF):
Essential for restoring facial anatomy and occlusion. This may involve
complex reconstruction of the midface.
Maxillomandibular Fixation (MMF): Often used to
stabilize the fracture during healing.
Craniofacial Reconstruction: In cases of severe
displacement or associated injuries, additional reconstructive
procedures may be necessary.
Postoperative Care:
Follow-Up: Regular follow-up to monitor healing,
occlusion, and any complications.
Oral Hygiene: Emphasize the importance of
maintaining oral hygiene to prevent infection.
Physical Therapy: May be necessary to restore
function and mobility.
General Considerations for All Le Fort Fractures
Antibiotic Prophylaxis: Consideration for prophylactic
antibiotics to prevent infection, especially in open fractures.
Nutritional Support: Ensure adequate nutrition,
especially if oral intake is compromised.
Psychological Support: Address any psychological impact
of facial injuries, especially in pediatric patients.
Drugs Used in Diabetes -Sulfonylureas
Pharmacology
Sulfonylureas
1st generation
tolbutamide
chlorpropamide
2nd generation
glyburide
glimepiride
glipizide
Mechanism
glucose normally triggers insulin release from pancreatic β cells by increasing intracellular ATP
→ closes K+ channels → depolarization → ↑ Ca2+ influx → insulin release
sulfonylureas mimic action of glucose by closing K+ channels in pancreatic β cells
→ depolarization → ↑ Ca2+ influx → insulin release
its use results in
↓ glucagon release
↑ insulin sensitivity in muscle and liver
Clinical use
type II DM
stimulates release of endogenous insulin
cannot be used in type I DM due to complete lack of islet function
Toxicity
first generation
disulfiram-like effects
especially chlorpropamide
second generation
hypoglycemia
weight gain
ERUPTION -Primary teeth
Dental Anatomy
ERUPTION
. Root completion (approximately 50% of the root is formed when eruption begins)
Generally mandibular teeth erupt before maxillary teeth,
Primary teeth
I. Emerge into the oral cavity as follows:
Maxillary Mandibular
Central Incisor 7½ months 6 months
Lateral incisor 9 months 7 months
Canine 18 months 16 months
First Molar 14 months 12 months
Second Molar 24months 20 months
The sequence of primary tooth development is central incisor, lateral incisor, first molar, second molar
3. Hard tissue formation begins between 4 and 6 months in utero
4. Crowns completed between 1½ and 10 months of age
5. Roots are completed between I½ and3 yearsof age 6 to 18 months after eruption
6. By age 3 years all of the primary and permanent teeth (except for the third molars) are in some stage of development
7. Root resorption of primary teeth is triggered by the pressure exerted by the developing permanent tooth; it is followed by primary tooth exfoliation in sequential patterns
8. The primary dentition ends when the first permanent tooth erupts
Erythromycin
Pharmacology
Erythromycin
used for people who have an allergy to penicillins. For respiratory tract infections, it has better coverage of atypical organisms, including mycoplasma. It is also used to treat outbreaks of chlamydia, syphilis, and gonorrhea.
Erythromycin is produced from a strain of the actinomyces Saccaropolyspora erythraea, formerly known as Streptomyces erythraeus.
Mechanism of action Erythromycin prevents bacteria from growing, by interfering with their protein synthesis. Erythromycin binds to the subunit 50S of the bacterial ribosome, and thus inhibits the translocation of peptides.
Erythromycin is easily inactivated by gastric acids, therefore all orally administered formulations are given as either enteric coated or as more stable salts or esters. Erythromycin is very rapidly absorbed, and diffused into most tissues and phagocytes. Due to the high concentration in phagocytes, erythromycin is actively transported to the site of infection, where during active phagocytosis, large concentrations of erythromycin are released.
Most of erythromycin is metabolised by demethylation in the liver. Its main route elimination route is in the bile, and a small portion in the urine.
Erythromycin's half-life is 1.5 hours.
Side-effects. More serious side-effects, such as reversible deafness are rare. Cholestatic jaundice, Stevens-Johnson syndrome and toxic epidermal necrosis are some other rare side effects that may occur.
Contraindications Earlier case reports on sudden death prompted a study on a large cohort that confirmed a link between erythromycin, ventricular tachycardia and sudden cardiac death in patients also taking drugs that prolong the metabolism of erythromycin (like verapamil or diltiazem)
erythromycin should not be administered in patients using these drugs, or drugs that also prolong the QT time.
INFLAMMATION
General Pathology
INFLAMMATION
Response of living tissue to injury, involving neural, vascular and cellular response.
ACUTE INFLAMMATION
It involves the formation of a protein .rich and cellullar exudate and the cardinal signs are calor, dolor, tumour, rubor and function loss
The basic components of the response are
Haemodynamic changes.
Permeability changes
Leucocyte events.
1. Haemodynamic Changes :
Transient vasoconstriction followed by dilatation.
Increased blood flow in arterioles.
More open capillary bed.
Venous engorgement and congestion.
Packing of microvasculature by RBC (due to fluid out-pouring)
Vascular stasis.
Change in axial flow (resulting in margination of leucocytes)
.2. Permeability Changes:
Causes.
Increased intravascular hydrostatic pressure.
Breakdown of tissue proteins into small molecules resulting in
increased tissue osmotic pressure.
Increased permeability due to chemical mediators, causing an
immediate transient response. .
Sustained response due to direct damage to microcirculation.
3. White Cell Events:
.Margination - due to vascular stasis and change in axial flow.
Pavementing - due to endothelial cells swollen and more sticky.
Leucocytes more adhesive.
Binding by a plasma component
Emigration - of leucocytes by amoeboid movement between endhothe1ial cells and beyond the basement membrane. The passive movement of RBCs through the gaps created during emigration is called diapedesis
Chemotaxis - This is a directional movement, especially of polymorphs and monocytes towards a concentration gradient resulting in aggregation of these cells at the site of inflammation. .Chemotactic agents may be:
Complement components. (C3and C5 fragments and C567)
Bacterial products.
Immune complexes, especially for monocyte.
Lymphocytic factor, especially for monocyte.
Phagocytosis - This includes recognition, engulfment and intracellular degradation. It is aided by .Opsonins., Specific antibodies., Surface provided by fibrin meshwork.
Functions of the fluid and cellular exudate
1. Dilution of toxic agent.
2. Delivers serum factors like antibodies and complement components to site of inflammation.
3. Fibrin formed aids In :
Limiting inflammation
Surface phagocytosis
Framework for repair.
4. Cells of the exudate:
Phagocytose and destroy the foreign agent.
Release lytic enzymes when destroyed, resulting in extracellular killing of organisms- and digestion of debris to enable healing to occur