NEET MDS Synopsis
Rocky Mountain Spotted Fever
General Pathology
Rocky Mountain Spotted Fever (Spotted Fever; Tick Fever; Tick Typhus)
An acute febrile disease caused by Rickettsia rickettsii and transmitted by ixodid ticks, producing high fever, cough, and rash.
Symptoms and Signs
The incubation period averages 7 days but varies from 3 to 12 days; the shorter the incubation period, the more severe the infection. Onset is abrupt, with severe headache, chills, prostration, and muscular pains. Fever reaches 39.5 or 40° C (103 or 104° F) within several days and remains high (for 15 to 20 days in severe cases),
Between the 1st and 6th day of fever, most patients develop a rash on the wrists, ankles, palms, soles, and forearms that rapidly extends to the neck, face, axilla, buttocks, and trunk. Often, a warm water or alcohol compress brings out the rash. Initially macular and pink, it becomes maculopapular and darker. In about 4 days, the lesions become petechial and may coalesce to form large hemorrhagic areas that later ulcerate
Neurologic symptoms include headache, restlessness, insomnia, delirium, and coma, all indicative of encephalitis. Hypotension develops in severe cases. Hepatomegaly may be present, but jaundice is infrequent. Localized pneumonitis may occur. Untreated patients may develop pneumonia, tissue necrosis, and circulatory failure, with such sequelae as brain and heart damage. Cardiac arrest with sudden death occasionally occurs in fulminant cases.
Oxygen Transport
PhysiologyOxygen Transport
In adult humans the hemoglobin (Hb) molecule
consists of four polypeptides:
two alpha (α) chains of 141 amino acids and
two beta (β) chains of 146 amino acids
Each of these is attached the prosthetic group heme.
There is one atom of iron at the center of each heme.
One molecule of oxygen can bind to each heme.
The reaction is reversible.
Under the conditions of lower temperature, higher pH, and increased oxygen pressure in the capillaries of the lungs, the reaction proceeds to the right. The purple-red deoxygenated hemoglobin of the venous blood becomes the bright-red oxyhemoglobin of the arterial blood.
Under the conditions of higher temperature, lower pH, and lower oxygen pressure in the tissues, the reverse reaction is promoted and oxyhemoglobin gives up its oxygen.
The Sphenoid Bone
Anatomy-> This is a wedge-shaped bone (G. sphen, wedge) is located anteriorly to the temporal bones.
-> It is a key bone in the cranium because it articulates with eight bones (frontal, parietal, temporal, occipital, vomer, zygomatic, palatine, and ethmoid).
-> It main parts are the body and the greater and lesser wings, which spread laterally from the body.
-> The superior surface of its body is shaped like a Turkish saddle (L. sella, a saddle); hence its name sella turcica.
-> It forms the hypophyseal fossa which contains the hypophysis cerebri or pituitary gland.
-> The sella turcica is bounded posteriorly by the dorsum sellae, a square plate of bone that projects superiorly and has a posterior clinoid process on each side.
-> Inside the body of the sphenoid bone, there are right and left sphenoid sinuses. The floor of the sella turcica forms the roof of these paranasal sinuses.
-> Studies of the sella turcica and hypophyseal fossa in radiographs or by other imaging techniques are important because they may reflect pathological changes such as a pituitary tumour or an aneurysm of the internal carotid artery. Decalcification of the dorsum sellae is one of the signs of a generalised increase in intracranial pressure.
Symptoms of Legionella pneumonia
Pathology
L: Lungs - Atypical pneumonia.
Relatively nonproductive cough
Dyspnea
Pleuritic or non pleuritic chest pain
Confluent or patchy infiltrates on x-ray
Random fact: Interstitial infiltrates aren’t seen often like in other atypical pneumonias.
E: Encephalon - Neurologic abnormalities.
Headache
Confusion or changes in mental status
Encephalopathy
G: Gastrointestinal symptoms.
Abdominal pain
Nausea
Vomiting
Watery diarrhea
ION: Na ion decreases.
Hyponatremia (serum sodium level of 131 meq/L)
Digital Radiology
Radiology
Digital Radiology
Advances in computer and X-ray technology now permit the use of systems that employ sensors in place of X-ray ?lms (with emulsion). The image is either directly or indirectly converted into a digital representation that is displayed on a computer screen.
DIGITAL IMAGE RECEPTORS
- charged coupled device (CCD) used
- Pure silicon divided into pixels.
- Electromagnetic energy from visible light or X-rays interacts with pixels to create an electric charge that can be stored.
- Stored charges are transmitted electronically and create an analog output signal and displayed via digital converter (analog to digital converter).
ADVANTAGES OF DIGITAL TECHNIQUE
Immediate display of images.
Enhancement of image (e.g., contrast, gray scale, brightness).
Radiation dose reduction up to 60%.
Major disadvantage: High initial cost of sensors. Decreased image resolution and contrast as compared to D speed ?lms.
DIRECT IMAGING
- CCD or complementary metal oxide semiconductor (CMOS) detector used that is sensitive to electromagnetic radiation.
- Performance is comparable to ?lm radiography for detection of periodontal lesions and proximal caries in noncavitated teeth.
INDIRECT IMAGING
- Radiographic ?lm is used as the image receiver (detector).
- Image is digitized from signals created by a video device or scanner that views the radiograph.
Sensors
STORAGE PHOSPHOR IMAGING SYSTEMS
Phosphor screens are exposed to ionizing radiation which excites BaFBR:EU+2 crystals in the screen storing the image.
A computer-assisted laser then promotes the release of energy from the crystals in the form of blue light.
The blue light is scanned and the image is reconstructed digitally.
ELECTRONIC SENSOR SYSTEMS
X-rays are converted into light which is then read by an electronic sensor such as a CCD or CMOS.
Other systems convert the electromagnetic radiation directly into electrical impulses.
Digital image is created out of the electrical impulses.
Anti-Infective and Anticariogenic Agents
PedodonticsAnti-Infective and Anticariogenic Agents in Human Milk
Human milk is not only a source of nutrition for infants but also contains
various bioactive components that provide anti-infective and anticariogenic
properties. These components play a crucial role in protecting infants from
infections and promoting oral health. Below are the key agents found in human
milk:
1. Immunoglobulins
Secretory IgA: The predominant immunoglobulin in human
milk, secretory IgA plays a vital role in mucosal immunity by preventing the
attachment of pathogens to mucosal surfaces.
IgG and IgM: These immunoglobulins also contribute to
the immune defense, with IgG providing systemic immunity and IgM being
involved in the initial immune response.
2. Cellular Elements
Lymphoid Cells: These cells are part of the immune
system and help in the recognition and response to pathogens.
Polymorphonuclear Leukocytes (Polymorphs): These white
blood cells are essential for the innate immune response, helping to engulf
and destroy pathogens.
Macrophages: These cells play a critical role in
phagocytosis and the immune response, helping to clear infections.
Plasma Cells: These cells produce antibodies,
contributing to the immune defense.
3. Complement System
C3 and C4 Complement Proteins: These components of the
complement system have opsonic and chemotactic activities, enhancing the
ability of immune cells to recognize and eliminate pathogens. They promote
inflammation and attract immune cells to sites of infection.
4. Unsaturated Lactoferrin and Transferrin
Lactoferrin: This iron-binding protein has
antimicrobial properties, inhibiting the growth of bacteria and fungi by
depriving them of iron.
Transferrin: Similar to lactoferrin, transferrin also
binds iron and plays a role in iron metabolism and immune function.
5. Lysozyme
Function: Lysozyme is an enzyme that breaks down
bacterial cell walls, providing antibacterial activity. It helps protect the
infant from bacterial infections.
6. Lactoperoxidase
Function: This enzyme produces reactive oxygen species
that have antimicrobial effects, contributing to the overall antibacterial
properties of human milk.
7. Specific Inhibitors (Non-Immunoglobulins)
Antiviral and Antistaphylococcal Factors: Human milk
contains specific factors that inhibit viral infections and the growth of
Staphylococcus bacteria, providing additional protection against infections.
8. Growth Factors for Lactobacillus Bifidus
Function: Human milk contains growth factors that
promote the growth of beneficial bacteria such as Lactobacillus bifidus,
which plays a role in maintaining gut health and preventing pathogenic
infections.
9. Para-Aminobenzoic Acid (PABA)
Function: PABA may provide some protection against
malaria, highlighting the potential role of human milk in offering broader
protective effects against various infections.
Connective tissue diseases
General Pathology
Connective tissue diseases
Marfan’s syndrome
a. Genetic transmission: autosomal dominant.
b. Characterized by a defective microfibril glycoprotein, fibrillin.
c. Clinical findings include tall stature, joints that can be hyperextended, and cardiovascular defects, including mitral valve prolapse and dilation of the ascending aorta.
Ehlers-Danlos syndrome
a. Genetic transmission: autosomal dominant or recessive.
b. This group of diseases is characterized by defects in collagen.
c. Clinical findings include hypermobile joints and highly stretchable skin. The skin also bruises easily. Oral findings include Gorlin’s sign and possible temporomandibular joint (TMJ) subluxation.
The oral mucosa may also appear more fragile and vulnerable to trauma.
MANDIBULAR SECOND MOLAR
Dental Anatomy
MANDIBULAR SECOND MOLAR
Facial: When compared to the first molar, the second molar crown is shorter both mesiodistally and from the cervix to the occlusal surface. The two well-developed buccal cusps form the occlusal outline. There is no distal cusp as on the first molar. A buccal developmental groove appears between the buccal cusps and passes midway down the buccal surface toward the cervix.
Lingual: The crown is shorter than that of the first molar. The occlusal outline is formed by the mesiolingual and distolingal cusps.
Proximal: The mesial profile resembles that of the first molar. The distal profile is formed by the distobuccal cusp, distal marginal ridge, and the distolingual cusp. Unlike the first molar, there is no distal fifth cusp.
Occlusal: There are four well developed cusps with developmental grooves that meet at a right angle to form the distinctive "+" pattern characteristic of this tooth.
Contact Points; When moving distally from first to third molar, the proximal surfaces become progressively more rounded. The net effect is to displace the contact area cervically and away from the crest of the marginal ridges.
Roots:-The mandibular second molar has two roots that are smaller than those of the first molar. When compared to first molar roots, those of the second tend to be more parallel and to have a more distal inclination.