NEET MDS Synopsis
AUTOCOIDS
Pharmacology
AUTOCOIDS
An organic substance, such as a hormone, produced in one part of organism and transported by the blood or lymph to another part of the organism where it exerts a physiologic effect on that part.
TYPES OF AUTACOIDS:
Amines : Histamine,5-Hydroxytryptamine.
Lipids : Prostaglandins, Leukotriens, Platelet activating factor.
Peptide : Bradykinin , angiotensin.
Hormones of the Pituitary
Physiology
The pituitary gland is pea-sized structure located at the base of the brain. In humans, it consists of two lobes:
the Anterior Lobe and
the Posterior Lobe
The Anterior Lobe
The anterior lobe contains six types of secretory cells All of them secrete their hormone in response to hormones reaching them from the hypothalamus of the brain.
Thyroid Stimulating Hormone (TSH)
TSH (also known as thyrotropin) is a glycoprotein The secretion of TSH is
stimulated by the arrival of thyrotropin releasing hormone (TRH) from the hypothalamus.
inhibited by the arrival of somatostatin from the hypothalamus.
TSH stimulates the thyroid gland to secrete its hormone thyroxine (T4).
Some develop antibodies against their own TSH receptors making more T4 causing hyperthyroidism. The condition is called thyrotoxicosis or Graves' disease.
Hormone deficiencies
A deficiency of TSH causes hypothyroidism: inadequate levels of T4 (and thus of T3 )..
Follicle-Stimulating Hormone (FSH)
FSH is a heterodimeric glycoprotein Synthesis and release of FSH is triggered by the arrival from the hypothalamus of gonadotropin-releasing hormone (GnRH).
FSH in females :In sexually-mature females, FSH (assisted by LH) acts on the follicle to stimulate it to release estrogens.
FSH in males :In mature males, FSH acts on spermatogonia stimulating (with the aid of testosterone) the production of sperm.
Luteinizing Hormone (LH)
LH is synthesized within the same pituitary cells as FSH and under the same stimulus (GnRH). It is also a heterodimeric glycoprotein
LH in females
In sexually-mature females, LH
stimulates the follicle to secrete estrogen in the first half of the menstrual cycle
a surge of LH triggers the completion of meiosis I of the egg and its release (ovulation) in the middle of the cycle
stimulates the now-empty follicle to develop into the corpus luteum, which secretes progesterone during the latter half of the menstrual cycle.
LH in males
LH acts on the interstitial cells (also known as Leydig cells) of the testes stimulating them to synthesize and secrete the male sex hormone, testosterone.
LH in males is also known as interstitial cell stimulating hormone (ICSH).
Prolactin (PRL)
Prolactin is a protein of 198 amino acids. During pregnancy it helps in the preparation of the breasts for future milk production. After birth, prolactin promotes the synthesis of milk.
Prolactin secretion is
stimulated by TRH
repressed by estrogens and dopamine.
Growth Hormone (GH)
Human growth hormone (also called somatotropin) is a protein
The GH-secreting cells are stimulated to synthesize and release GH by the intermittent arrival of growth hormone releasing hormone (GHRH) from the hypothalamus. GH promotes body growth
In Child
hyposecretion of GH produces dwarfism
hypersecretion leads to gigantism
In adults, a hypersecretion of GH leads to acromegaly.
ACTH — the adrenocorticotropic hormone
ACTH acts on the cells of the adrenal cortex, stimulating them to produce
glucocorticoids, like cortisol
mineralocorticoids, like aldosterone
androgens (male sex hormones, like testosterone
Hypersecretion of ACTH cause of Cushing's disease.
DAMAGE TO THE SPINAL NERVES AND SPINAL CORD
Physiology
Damage to Spinal Nerves and Spinal Cord
Damage
Possible cause of damage
Symptoms associated with innervated area
Peripheral nerve
Mechanical injury
Loss of muscle tone. Loss of reflexes. Flaccid paralysis. Denervation atrophy. Loss of sensation
Posterior root
Tabes dorsalis
Paresthesia. Intermittent sharp pains. Decreased sensitivity to pain. Loss of reflexes. Loss of sensation. Positive Romberg sign. High stepping and slapping of feet.
Anterior Horn
Poliomyelitis
Loss of muscle tone. Loss of reflexes. Flaccid paralysis. Denervation atrophy
Lamina X (gray matter)
Syringomyelia
Bilateral loss of pain and temperature sense only at afflicted cord level. Sensory dissociation. No sensory impairment below afflicted level
Anterior horn and lateral corticospinal tract
Amyotrophic lateral sclerosis
Muscle weakness. Muscle atrophy. Fasciculations of hand and arm muscles. Spastic paralysis
Posterior and lateral funiculi
Subacute combined degeneration
Loss of position sense. Loss of vibratory sense. Positive Romberg sign. Muscle weakness. Spasticity. Hyperactive tendon reflexes. Positive Babinski sign.
Hemisection of the spinal cord
Mechanical injury
Brown-Sequard syndrome
Below cord level on injured side
Flaccid paralysis. Hyperactive tendon reflexes. Loss of position sense. Loss of vibratory sense. Tactile impairment
Below cord level on opposite side beginning one or two segments below injury
Loss of pain and temperature
Membrane Structure & Function
PhysiologyMembrane Structure & Function
Cell Membranes
Cell membranes are phospholipid bilayers (2 layers)
Bilayer forms a barrier to passage of molecules in an out of cell
Phospholipids = glycerol + 2 fatty acids + polar molecule (i.e., choline) + phosphate
Cholesterol (another lipid) stabilizes cell membranes
the hydrophobic tails of the phospholipids (fatty acids) are together in the center of the bilayer. This keeps them out of the water
Membranes Also Contain Proteins
Proteins that penetrate the membrane have hydrophobic sections ~25 amino acids long
Hydrophobic = doesn't like water = likes lipids
Membrane proteins have many functions:
receptors for hormones
pumps for transporting materials across the membrane
ion channels
adhesion molecules for holding cells to extracellular matrix
cell recognition antigens
SULPHONAMIDES
Pharmacology
SULPHONAMIDES
Derivative of sulphonilamide (Para-amino Benzene (PABA ) sulphonamide).
Anti-bacterial spectrum
Bacteriostatic to gram + and gram - bacteria. but bactericidal concentrations arce attained in urine. S pyogencs. H influenzae.E coli, few- Staph aureus. gonococci. pneumococci, proteus, shigella and Lymphogranuloma venereum.
Mechanism of action
Inhibits bacterial folate synthetase as they compete with PABA
Less soluble in acid urine and may precipitate to cause crystalluria.
Accumulate in patients with renal failure and can cause toxicity
Classification
Shart Acting (4-8 Hrs) sulphadiazine, sulphamethizole.
Intermediate acting(8-16 Hrs): sulphamethoxazole , sulphaphenazole
Long Acting(l-7days): sulphamethoxypyridazine.
Ultralong Acting(3-8days): sulfaline
Adverse effects
I. nausea, vomiting and epigastric pain
2. crystalluria
3. hypersensitivity-like polyarthritis nodosa. Steven-Johnson Syndrome. photosenstivity
4.hemolysis in G-6PD deficiency
5. kernicterus
They inhibit metabolism of phenytoin. tolbutamide. methotrexate
Therapeutic Use
UTI Meningitis, Streptococcal pharyngitis, Bacillary Dysentery
Periodontium
Dental Anatomy
The periodontium, which is the supporting structure of a tooth, consists of the cementum, periodontal ligaments, gingiva, and alveolar bone. Cementum is the only one of these that is a part of a tooth. Alveolar bone surrounds the roots of teeth to provide support and creates what is commonly called a "socket". Periodontal ligaments connect the alveolar bone to the cementum, and the gingiva is the surrounding tissue visible in the mouth.
Periodontal ligaments
Histology of the Periodontal Ligament (PDL)
Embryogenesis of the periodontal ligament
The PDL forms from the dental follicle shortly after root development begins
The periodontal ligament is characterized by connective tissue. The thinnest portion is at the middle third of the root. Its width decreases with age. It is a tissue with a high turnover rate.
The Oral Cavity
AnatomyThe Oral Cavity
The oral cavity (mouth) consists of two parts: the vestibule and the mouth proper.
The vestibule is the slit-like spaced between the cheeks and the lips and the teeth and gingivae.
It is the entrance of the digestive tract and is also used for breathing.
The vestibule communicates with the exterior through the orifice of the mouth.
The oral cavity is bounded:
Externally: by the cheeks and lips.
Roof of oral cavity: formed by the palate.
Posteriorly: the oral cavity communicates with the oropharynx.
Pharmacology
Pharmacology
Pharmacology is the study of drugs and the way they interact with living systems. Clinical pharmacology is the study of drugs in humans.
A drug is any chemical that can effect living processes.
Therapeutics: the medical use of drugs.
An ideal drug has several important properties. Three of these properties are of utmost importance: effectiveness, safety and selectivity.
Effectiveness: This is the most important quality that a drug can have. Effectiveness refers to the drug's ability to do what it is supposed to do.
Safety: Although no drug can be totally safe, proper usage can lessen the risks of adverse effects.
Selectivity: A truly selective drug would have no side effects, and would effect only the body process' for which it is designed and given. Therefore, there is no such thing as a selective drug.
Pharmacokinetics: The way the body deals with a drug. Pharmacokinetics is concerned with the processes of absorption, distribution, metabolism and excretion.
Pharmacodynamics: What a drug does to the body.
Pharmacokinetics and pharmacodynamics are two of the processes that determine how a person will respond to a drug. Other factors include how a drug is administered (dose, route, and timing of administration), interactions with other drugs, and individual physiological variables (weight, age, function of body systems).