NEET MDS Synopsis
Thyroid Hormones
Biochemistry
Thyroid Hormones
Thyroid hormones (T4 and T3) are tyrosine-based hormones produced by the follicular cells of the thyroid gland and are regulated by TSH made by the thyrotropes of the anterior pituitary gland, are primarily responsible for regulation of metabolism. Iodine is necessary for the production of T3 (triiodothyronine) and T4 (thyroxine).
A deficiency of iodine leads to decreased production of T3 and T4, enlarges the thyroid tissue and will cause the disease known as goitre.
Thyroid hormones are transported by Thyroid-Binding Globulin
Thyroxine binding globulin (TBG), a glycoprotein binds T4 and T3 and has the capacity to bind 20 μg/dL of plasma.
Diseases
1. Hyperthyroidism (an example is Graves Disease) is the clinical syndrome caused by an excess of circulating free thyroxine, free triiodothyronine, or both. It is a common disorder that affects approximately 2% of women and 0.2% of men.
2 Hypothyroidism (an example is Hashimoto’s thyroiditis) is the case where there is a deficiency of thyroxine, triiodiothyronine, or both.
Abnormalities of Salt, Water or pH
PhysiologyAbnormalities of Salt, Water or pH
Examples:
Hyperkalemia: caused by kidney disease & medical malpractice
High K+ in blood- can stop the heart in contraction (systole)
Dehydration: walking in desert- can lose 1-2 liters/hour through sweat
Blood becomes too viscous to circulate well -> loss of temperature regulation -> hyperthermia, death
Acidosis: many causes including diabetes mellitus and respiratory problems; can cause coma, death
Nutrition and tooth development
Dental Anatomy
Nutrition and tooth development
As in other aspects of human growth and development, nutrition has an effect on the developing tooth. Essential nutrients for a healthy tooth include calcium, phosphorus, fluoride, and vitamins A, C, and D. Calcium and phosphorus are needed to properly form the hydroxyapatite crystals, and their levels in the blood are maintained by Vitamin D. Vitamin A is necessary for the formation of keratin, as Vitamin C is for collagen. Fluoride is incorporated into the hydroxyapatite crystal of a developing tooth and makes it more resistant to demineralization and subsequent decay.
Deficiencies of these nutrients can have a wide range of effects on tooth development. In situations where calcium, phosphorus, and vitamin D are deficient, the hard structures of a tooth may be less mineralized. A lack of vitamin A can cause a reduction in the amount of enamel formation. Fluoride deficency causes increased demineralization when the tooth is exposed to an acidic environment, and also delays remineralization. Furthermore, an excess of fluoride while a tooth is in development can lead to a condition known as fluorosis.
Examples of calculations of doses of vasoconstrictors
Pharmacology
Examples of calculations of doses of vasoconstrictors
Ratio concentrations represent grams per millilitre
1:100,000 = 0.01 mg/mL or 10 µg/mL
1:200,000 = 0.005 mg/mL or 5 µg/mL
1:50,000 = 0.02 mg/mL or 20 µg/mL
1 cartridge of epinephrine 1:200,000 = 9 µg
1 cartridge of epinephrine 1:100,000 = 18 µg
1 cartridge of epinephrine 1:50,000 = 36 µg
1 cartridge of levonordefrin 1:20,000 = 90 µg
Types of Removable Orthodontic Appliances
OrthodonticsTypes of Removable Orthodontic Appliances
Functional Appliances:
Purpose: Designed to modify the growth of the jaw
and improve the relationship between the upper and lower teeth.
Examples:
Bionator: Encourages forward positioning of the
mandible.
Frankel Appliance: Used to modify the position
of the dental arches and improve facial aesthetics.
Retainers:
Purpose: Used to maintain the position of teeth
after orthodontic treatment.
Types:
Hawley Retainer: A custom-made acrylic plate
with a wire framework that holds the teeth in position.
Essix Retainer: A clear, plastic retainer that
fits over the teeth, providing a more aesthetic option.
Space Maintainers:
Purpose: Used to hold space for permanent teeth
when primary teeth are lost prematurely.
Types:
Band and Loop: A metal band placed on an
adjacent tooth with a loop extending into the space.
Distal Shoe: A space maintainer used in the
lower arch to maintain space for the first molar.
Aligners:
Purpose: Clear plastic trays that gradually move
teeth into the desired position.
Examples:
Invisalign: A popular brand of clear aligners
that uses a series of custom-made trays to achieve tooth movement.
Expansion Appliances:
Purpose: Used to widen the dental arch,
particularly in cases of crossbite or narrow arches.
Examples:
Rapid Palatal Expander (RPE): A device that
applies pressure to the upper molars to widen the maxilla.
Components of Removable Orthodontic Appliances
Baseplate: The foundation of the appliance, usually
made of acrylic, which holds the other components in place.
Active Components: Springs, screws, or other mechanisms
that exert forces on the teeth to achieve movement.
Retention Components: Clasps or other features that
help keep the appliance securely in place during use.
Adjustable Parts: Some appliances may have adjustable
components to fine-tune the force applied to the teeth.
Indications for Use
Correction of Malocclusions: Removable appliances can
be used to address various types of malocclusions, including crowding,
spacing, and crossbites.
Space Maintenance: To hold space for permanent teeth
when primary teeth are lost prematurely.
Tooth Movement: To move teeth into desired positions,
particularly in growing patients.
Retention: To maintain the position of teeth after
orthodontic treatment.
Jaw Relationship Modification: To influence the growth
of the jaw and improve the relationship between the dental arches.
Advantages of Removable Orthodontic Appliances
Patient Compliance: Patients can remove the appliance
for eating, brushing, and social situations, which can improve compliance.
Hygiene: Easier to clean compared to fixed appliances,
reducing the risk of plaque accumulation and dental caries.
Flexibility: Can be adjusted or modified as treatment
progresses.
Less Discomfort: Generally, removable appliances are
less uncomfortable than fixed appliances, especially during initial use.
Aesthetic Options: Clear aligners and other aesthetic
appliances can be more visually appealing to patients.
Disadvantages of Removable Orthodontic Appliances
Compliance Dependent: The effectiveness of removable
appliances relies heavily on patient compliance; if not worn as prescribed,
treatment may be delayed or ineffective.
Limited Force Application: They may not be suitable for
complex tooth movements or significant skeletal changes.
Adjustment Period: Some patients may experience
discomfort or difficulty speaking initially.
Duodenum
PhysiologyAs the contents of the stomach become thoroughly liquefied, they pass into the duodenum, the first segment of the small intestine. The duodenum is the first 10" of the small intestine
Two ducts enter the duodenum:
one draining the gall bladder and hence the liver
the other draining the exocrine portion of the pancreas.
From the intestinal mucosal cells, and from the liver and gallbladder. Secretions from the pancreas and bile from the gallbladder enter the duodenum through the hepatopancreatic ampulla and the sphincter of Oddi. These lie where the pancreatic duct and common bile duct join before entering the duodenum. The presence of fatty chyme in the duodenum causes release of the hormone CCK into the bloodstream. CCK is one of the enterogastrones and its main function, besides inhibiting the stomach, is to stimulate the release of enzymes by the pancreas, and the contraction of the gallbladder to release bile. It also stimulates the liver to produce bile. Consumption of excess fat results in excessive bile production by the liver, and this can lead to the formation of gallstones from precipitation of the bile salts.
The acid in the chyme stimulates the release of secretin which causes the pancreas to release bicarbonate which neutralizes the acidity
WETTABILITY
Dental Materials
WETTABILITY
To minimise the irregularities on the investment & the casting a wetting agent can be used .
FUNCTIONS OF A WETTING AGENT
1 . Reduce contact angle between liquid & wax surface .
2 .Remove any oily film left on wax pattern .
Parasitic Disease
General Pathology
Parasitic
1. Leishmania produce 3 kinds of disease in man
- visceral leishmaniasis (kala azar) due to Leishmania donovani complex,
- cutaneous leishmaniasis due to Leishmania tropica complex, and
- mucocutaneous leishmaniasis due to Leishmania braziliensis.
- cutaneous (Oriental sore) and mucocutansous leishmaniasis limit themselves to the skinalone (ulcers) in the former disease and skin plus mucous membranes in the latter variant.
- the diagnosis of cutaneous or mucocutaneous leishmaniasis is made by biopsy, culture, skin test, or serologic tests
- the laboratory diagnosis of visceral leishmaniasis is made by performing a bone marrow aspirate and finding the leishmanial forms in macrophages, by culture, by hamster inoculation, or by serology.
- recovery from the cutaneous form incurs immunity.
- treatment: stibogluconate