NEET MDS Synopsis
Thyroid goitres
General Pathology
Thyroid goitres
A goitre is any enlargement of part or whole of the thyroid gland. There are two types:
1. Toxic goitre, i.e. goitre associated with thyrotoxicosis.
2. Non-toxic goitre, i.e. goitre associated with normal or reduced levels of thyroid hormones.
Toxic goitre
Graves disease
This is the most common cause of toxic goitre
Toxic multinodular goitre
This results from the development of hyperthyroidism in a multinodular goitre
Non-toxic goitres
Diffuse non-toxic goitre (simple goitre)
This diffuse enlargement of the thyroid gland is classified into:
Endemic goitre—due to iodine deficiency. Endemic goiter occurs in geographic areas (typically mountainous)) where the soil, water, and food supply contain little iodine. The term endemic is used when goiters are present in more than 10% of the population in a given region. With increasing availability of dietary iodine supplementation, the frequency and severity of endemic goiter have declined significantly. Sporadic goiter is less common than endemic goiter. The condition is more common in females than in males, with a peak incidence in puberty or young adult life, when there is an
increased physiologic demand for T4.
Sporadic goitre—caused by goitrogenic agents (substances that induce goitre formation) or familial in origin. Examples of goitrogenic agents include certain cabbage species, because of their thiourea content, and specific drugs or chemicals, such as iodide, paraminosalicylic acid and drugs used in the treatment of thyrotoxicosis. Familial cases show inherited autosomal recessive traits, which interfere with hormone synthesis via various enzyme pathways (these are dyshormonogenic goitres).
Hereditary enzymatic defects interfering with thyroid hormone synthesis (dyshormonogenetic goiter).
Physiological goitre—enlargement of the thyroid gland in females during puberty or pregnancy; the reason is unclear.
Multinodular goitre
This is the most common cause of thyroid enlargement and is seen particularly in the elderly (nearly all simple goitres eventually become multinodular). The exact aetiology is uncertain but it may represent an uneven responsiveness of various parts of the thyroid to fluctuating TSH levels over a period of many years.
Morphological features are:
• Irregular hyperplastic enlargement of the entire thyroid gland due to the development of wellcircumscribed nodules of varying size.
• Larger nodules filled with brown, gelatinous colloid; consequently, it is often termed multinodular colloid goitres.
Clinical features
- A large neck mass, goiters may also cause airway obstruction, dysphagia, and compression of large vessels in the neck and upper thorax.
- A hyperfunctioning ("toxic") nodule may develop within a long-standing goiter, resulting in hyperthyroidism. This condition is not accompanied by the infiltrative ophthalmopathy and dermopathy.
- Less commonly, there may be hypothyroidism.
Age changes in the dentition
Dental Anatomy
Age changes in the dentition
I. After the teeth have reached full occlusion, microscopic tooth movements occur to compensate for wear at the contact area (Mesial Drift) and occlusal surfaces (by Deposition of cementum at the root apex)
2. Attrition of incisal ridges and cusp tips may be so severe that dentin may become exposed and intrinsically stained
3. Secondary dentin may be formed in response to dental caries, trauma, and aging and result in decreased pulp size and tooth sensation
Third Generation Cephalosporins
Pharmacology
Third Generation Cephalosporins
Prototype drugs are CEFOTAXIME (IV) and CEFIXIME (oral). CEFTAZIDIME (for Pseudomonas aeruginosa.).
Further expansion of Gm negative spectrum to include hard to treat organisms such as Enterobacter, Serratia, and Pseudomonas.
In addition to better Gm negative spectrum, this group has improved pharmacokinetic properties (longer half-lives) that allow once daily dosing with some agents. In general, activity toward Gm + bacteria is reduced. These are specialty antibiotics that should be reserved for specific uses.
Enterobacteriaciae that are almost always sensitive (>95% sensitive)
E. coli
Proteus mirabilis (indole –)
Proteus vulgaris (indole +)
Klebsiella pneumoniae
Gram negative bacilli that are generally sensitive (>75% sensitive)
Morganella morganii
Providencia retgerri
Citrobacter freundii
Serratia marcescens
Pseudomonas aeruginosa (Ceftazidime only)
Gram negative bacilli that are sometimes sensitive (<75% sensitive)
Enterobacter
Stenotrophomonas (Xanthomonas) maltophilia (Cefoperazone & Ceftazidime only)
Acinetobacter
--> cefepime & cefpirome are promising for these bacteria
Bacteria that are resistant
Listeria monocytogenes
Pseudomonas cepacia
Enterococcus sp.
Uses
1. Gram negative septicemia & other serious Gm – infections
2. Pseudomonas aeruginosa infections (Ceftazidime - 90% effective)
3. Gram negative meningitis - Cefotaxime, Ceftriaxone, Cefepime. For empiric therapy add vancomycin ± rifampin to cover resistant Strep. pneumoniae
4. Gonorrhea - Single shot of Ceftriaxone is drug of choice. Oral cefixime and ceftibuten are also OK.
5. Complicated urinary tract infections, pyelonephritis
6. Osteomyelitis - Ceftriaxone in home health care situations
7. Lyme disease - ceftriaxone in home health care situations
Respiratory Viral Diseases
General Pathology
Respiratory Viral Diseases
Respiratory viral infections cause acute local and systemic illnesses. The common cold, influenza, pharyngitis, laryngitis (including croup), and tracheobronchitis are common.
An acute, usually afebrile, viral infection of the respiratory tract, with inflammation in any or all airways, including the nose, paranasal sinuses, throat, larynx, and sometimes the trachea and bronchi.
Etiology and Epidemiology
Picornaviruses, especially rhinoviruses and certain echoviruses and coxsackieviruses, cause the common cold. About 30 to 50% of all colds are caused by one of the > 100 serotypes of rhinoviruses.
Symptoms and Signs
Clinical symptoms and signs are nonspecific.
After an incubation period of 24 to 72 h, onset is abrupt, with a burning sensation in the nose or throat, followed by sneezing, rhinorrhea, and malaise.
Characteristically, fever is not present, particularly with a rhinovirus or coronavirus. Pharyngitis usually develops early; laryngitis and tracheobronchitis vary by person and causative agent. Nasal secretions are watery and profuse during the first days, but become more mucoid and purulent.
Cough is usually mild but often lasts into the 2nd wk.
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.
Mylohyoid Muscle
AnatomyMylohyoid Muscle
Origin: Mylohyoid line of the mandible.
Insertion: Median raphe and body of the hyoid bone.
Nerve Supply: Nerve to mylohyoid (branch of the
trigeminal nerve, CN V3).
Arterial Supply: Sublingual branch of the lingual
artery and submental branch of the facial artery.
Action: Elevates the hyoid bone, base of the tongue,
and floor of the mouth; depresses the mandible.
Introduction. The Jaws and Dental Arches
Dental Anatomy
Introduction. The Jaws and Dental Arches
The teeth are arranged in upper and lower arches. Those of the upper are called maxillary; those of the lower are mandibular.
The maxilla is actually two bones forming the upper jaw; they are rigidly attached to the skull..
The mandible is a horseshoe shaped bone which articulates with the skull by way of the temporomandibular joint the TMJ.
The dental arches, the individual row of teeth forming a tooth row attached to their respective jaw bones have a distinctive shape known as a catenary arch.
Periodontium
Dental Anatomy
The periodontium consists of tissues supporting and investing the tooth and includes cementum, the periodontal ligament (PDL), and alveolar bone.
Parts of the gingiva adjacent to the tooth also give minor support, although the gingiva is Not considered to be part of the periodontium in many texts. For our purposes here, the groups Of gingival fibers related to tooth investment are discussed in this section.