The thyroid gland is located in the neck and produces three main hormones: T4, T3, and calcitonin. T4 makes up 90% of hormone production while T3 is 9-10%. The gland contains follicles lined with cells that secrete thyroglobulin into the follicular cavity. Iodine is added to thyroglobulin's tyrosine residues to form T4 and T3, which are stored in thyroglobulin vesicles until needed. When secreted into blood, T4 and T3 bind transport proteins while T3 has a faster action time due to weaker binding. The thyroid regulates metabolism through hormone synthesis and secretion.
Thyroid hormone,
structure of hormone,
synthesis of thyroid hormone,
mechanism of Thyroid hormone action,
Physiological effect of Hormone,
Disorders related with thyroid hormone,
drugs used in treatment for the thyroid disorders.
Thyroid hormone (The Guyton and Hall physiology)Maryam Fida
THYROID HORMONE
Location:
The thyroid gland located below the larynx on each side of and anterior to the trachea.
Largest Endocrine Hormone
Secretion:
secretes:
1. thyroxine (T4)
2. triiodothyronine (T3)
3. Also secretes calcitonin (an important hormone for calcium metabolism)
Cell: Thyrotopes
secretion is controlled by thyroid-stimulating hormone (TSH) from the anterior pituitary gland.
93% T4 & 7% T3
T4→T3 in tissues
Qualitatively same
Differ in Rapidity & Intensity of action.
T3 is 4 times more potent than T4, but decrease conc. In blood & decrease half life.
T3 and T4 combine mainly with thyroxine-binding globulin.
More than 90% of Thyroid hormone that binds with cellular receptors is T3.
T4
No effect for 2-3 days after injection
Long Latent Period.
Activity peaks in 10-12 days & ↓↓ with a half life of 15 days.
In some cases it takes 6 weeks-2 months.
T3
4 times rapid
Latent Period 6-12 hours
Peak in 2-3 days
Composed of large numbers of closed follicles filled with colloid and lined with cuboidal epithelial cells that secrete into the interior of the follicles
The major component of colloid is the large glycoprotein Thyroglobulin contains the thyroid hormones within its molecule.
50mg/year, 1mg/week
Ingested iodine in the form of iodides
Iodides ingested orally are absorbed from GIT
⅕ removed from the blood by thyroid cells for synthesis of hormones; rest excreted through kidneys.
Basal membrane of thyroid cells has an active pump to push iodides to interior (Iodine Pump).
Normally 30% more conc. Inside
Max. active 250% more conc. Inside
The rate of Iodine trapping is influenced by conc. of TSH
TSH stimulates and hypophysectomy greatly diminishes the activity of the iodide pump in thyroid cells.
Thyroid hormone,
structure of hormone,
synthesis of thyroid hormone,
mechanism of Thyroid hormone action,
Physiological effect of Hormone,
Disorders related with thyroid hormone,
drugs used in treatment for the thyroid disorders.
Thyroid hormone (The Guyton and Hall physiology)Maryam Fida
THYROID HORMONE
Location:
The thyroid gland located below the larynx on each side of and anterior to the trachea.
Largest Endocrine Hormone
Secretion:
secretes:
1. thyroxine (T4)
2. triiodothyronine (T3)
3. Also secretes calcitonin (an important hormone for calcium metabolism)
Cell: Thyrotopes
secretion is controlled by thyroid-stimulating hormone (TSH) from the anterior pituitary gland.
93% T4 & 7% T3
T4→T3 in tissues
Qualitatively same
Differ in Rapidity & Intensity of action.
T3 is 4 times more potent than T4, but decrease conc. In blood & decrease half life.
T3 and T4 combine mainly with thyroxine-binding globulin.
More than 90% of Thyroid hormone that binds with cellular receptors is T3.
T4
No effect for 2-3 days after injection
Long Latent Period.
Activity peaks in 10-12 days & ↓↓ with a half life of 15 days.
In some cases it takes 6 weeks-2 months.
T3
4 times rapid
Latent Period 6-12 hours
Peak in 2-3 days
Composed of large numbers of closed follicles filled with colloid and lined with cuboidal epithelial cells that secrete into the interior of the follicles
The major component of colloid is the large glycoprotein Thyroglobulin contains the thyroid hormones within its molecule.
50mg/year, 1mg/week
Ingested iodine in the form of iodides
Iodides ingested orally are absorbed from GIT
⅕ removed from the blood by thyroid cells for synthesis of hormones; rest excreted through kidneys.
Basal membrane of thyroid cells has an active pump to push iodides to interior (Iodine Pump).
Normally 30% more conc. Inside
Max. active 250% more conc. Inside
The rate of Iodine trapping is influenced by conc. of TSH
TSH stimulates and hypophysectomy greatly diminishes the activity of the iodide pump in thyroid cells.
This PPT gives the students the basic physiology of the Thyroid gland. It is the only Endocrine gland that can be palpable with your hands. Very useful to M.B.B.S; B.D.S as well as PG students.
The thyroid hormones, triiodothyronine (T3) and its prohormone, thyroxine (T4), are tyrosine-based hormones produced by the thyroid gland that are primarily responsible for regulation of metabolism. Iodine is necessary for the production of T3 and T4. A deficiency of iodine leads to decreased production of T3 and T4, enlarges the thyroid tissue and will cause the disease known as simple goitre. The major form of thyroid hormone in the blood is thyroxine (T4), which has a longer half-life than T3.The ratio of T4 to T3 released into the blood is roughly 20 to 1. T4 is converted to the active T3 (three to four times more potent than T4) within cells by deiodinases (5'-iodinase). These are further processed by decarboxylation and deiodination to produce iodothyronamine (T1a) and thyronamine (T0a). All three isoforms of the deiodinases are selenium-containing enzymes, thus dietary selenium is essential for T3 production.
A power point presentation on thyroid hormones and thyroid inhibitors on subject of pharmacology suitable for reading by undergraduate medical students.
This PPT gives the students the basic physiology of the Thyroid gland. It is the only Endocrine gland that can be palpable with your hands. Very useful to M.B.B.S; B.D.S as well as PG students.
The thyroid hormones, triiodothyronine (T3) and its prohormone, thyroxine (T4), are tyrosine-based hormones produced by the thyroid gland that are primarily responsible for regulation of metabolism. Iodine is necessary for the production of T3 and T4. A deficiency of iodine leads to decreased production of T3 and T4, enlarges the thyroid tissue and will cause the disease known as simple goitre. The major form of thyroid hormone in the blood is thyroxine (T4), which has a longer half-life than T3.The ratio of T4 to T3 released into the blood is roughly 20 to 1. T4 is converted to the active T3 (three to four times more potent than T4) within cells by deiodinases (5'-iodinase). These are further processed by decarboxylation and deiodination to produce iodothyronamine (T1a) and thyronamine (T0a). All three isoforms of the deiodinases are selenium-containing enzymes, thus dietary selenium is essential for T3 production.
A power point presentation on thyroid hormones and thyroid inhibitors on subject of pharmacology suitable for reading by undergraduate medical students.
Thyroid and its pathology (Hypothyroidism).Vikas Reddy
GREEK :- THYREOS – SHIELD ; EIDOS – FORM
1.LOCATION:- Anterior to trachea in between the cricoid cartilage and the suprasternal notch.
2.SHAPE:- It has 2 lobes connected with an isthmus, each lobe in turn has two poles.
3.Weighs around 10-20 gm, highly vascular and soft in consistency.
4. 4 Parathyroid glands which secrete PTH are located posterior to each pole of thyroid
The RLN traverse the lateral border of thyroid gland and must be identified during thyroid surgery to avoid injury and vocal cord paralysis.
Develops from the floor of primitive pharynx during the 3rd week of gestation.
Fetal cells in which developmental transcription factors TTF-1,TTF-2 & PAX-8 are expressed selectively form the thyroid gland ,secondly they result in induction of thyroid specific genes
Tg,TPO,NIS,TSH-R.
Mutations-THYROID AGENESIS & DYSHORMONOGENESIS(CONG. HYPOTHYROIDISM).
The developing gland migrates along the thyroglossal duct to reach its final location in the neck.
LINGUAL THYROID AND THYROGLOSSAL DUCT CYST.
Thyroid hormone synthesis begins at about 11 weeks of gestation.
Until 11 week of gestation and even later, it is the maternal thyroid hormones which cross the placenta to reach the fetus and aid its development.
Therefore a child born to a hypothyroid mother would suffer from features of congenital hypothyroidism.
Secondly if the mother has TSH-R blocking antibodies or has received anti thyroid therapy during pregnancy, might lead to transient congenital hypothyroidism.
This slideshow gives you a information about hormone thyroid and its clinical activity and molecular mechanism. And also hormone abnormalities and drugs used to treat them .
hyperthyroidism and hypothyroidism is discussed along with drugs used to overcome those condition.
Thyroid function tests (TFTs) are the most frequently ordered endocrine investigations in children and adolescents.
Abnormalities in TFTs can help in diagnosis of primary thyroid disorders (i.e. disorders in which the defect is at the thyroid level) as well as secondary or central thyroid disorders (in which defect is at the pituitary level).
- The thyroid gland is the largest, butterfly-shaped endocrine glands & is located at the base of the neck immediately below the Larynx, on each side of & anterior to the trachea.The thyroid gland consists of two lobes of endocrine tissue (lying on either side of trachea) joined in the middle by a narrow portion of the gland called as the Isthmus.The thyroid has one ofthe highest rates of blood flow per gram of tissue. - In a normal adult male, it weighs 15-20 g but is capable of enormous growth, sometimes achieving a weight of several hundred grams.
Basavarajeeyam is an important text for ayurvedic physician belonging to andhra pradehs. It is a popular compendium in various parts of our country as well as in andhra pradesh. The content of the text was presented in sanskrit and telugu language (Bilingual). One of the most famous book in ayurvedic pharmaceutics and therapeutics. This book contains 25 chapters called as prakaranas. Many rasaoushadis were explained, pioneer of dhatu druti, nadi pareeksha, mutra pareeksha etc. Belongs to the period of 15-16 century. New diseases like upadamsha, phiranga rogas are explained.
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Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
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Muktapishti is a traditional Ayurvedic preparation made from Shoditha Mukta (Purified Pearl), is believed to help regulate thyroid function and reduce symptoms of hyperthyroidism due to its cooling and balancing properties. Clinical evidence on its efficacy remains limited, necessitating further research to validate its therapeutic benefits.
Basavarajeeyam is a Sreshta Sangraha grantha (Compiled book ), written by Neelkanta kotturu Basavaraja Virachita. It contains 25 Prakaranas, First 24 Chapters related to Rogas& 25th to Rasadravyas.
CDSCO and Phamacovigilance {Regulatory body in India}NEHA GUPTA
The Central Drugs Standard Control Organization (CDSCO) is India's national regulatory body for pharmaceuticals and medical devices. Operating under the Directorate General of Health Services, Ministry of Health & Family Welfare, Government of India, the CDSCO is responsible for approving new drugs, conducting clinical trials, setting standards for drugs, controlling the quality of imported drugs, and coordinating the activities of State Drug Control Organizations by providing expert advice.
Pharmacovigilance, on the other hand, is the science and activities related to the detection, assessment, understanding, and prevention of adverse effects or any other drug-related problems. The primary aim of pharmacovigilance is to ensure the safety and efficacy of medicines, thereby protecting public health.
In India, pharmacovigilance activities are monitored by the Pharmacovigilance Programme of India (PvPI), which works closely with CDSCO to collect, analyze, and act upon data regarding adverse drug reactions (ADRs). Together, they play a critical role in ensuring that the benefits of drugs outweigh their risks, maintaining high standards of patient safety, and promoting the rational use of medicines.
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
The Gram stain is a fundamental technique in microbiology used to classify bacteria based on their cell wall structure. It provides a quick and simple method to distinguish between Gram-positive and Gram-negative bacteria, which have different susceptibilities to antibiotics
2. Thyroid Gland (Anatomy)
One of the largest endocrine gland situated at
the root of neck on either side of the trachea.
Located immediately below the larynx
Has two lobes, connected in the middle by an
isthmus.
It weighs about 20 to 40 g in adults.
Structure and the function of the thyroid gland
change in different stages of the sexual cycle in
females
3.
4. Histology
Composed of large number of closed follicles.
Follicles are lined with cuboidal epithelial cells,
called the follicular cells.
Follicular cavity is filled with a colloidal substance
known as thyroglobulin, which is secreted by the
follicular cells.
Follicular cells also secrete T3 and T4.
In between the follicles, the parafollicular cells are
present which secrete calcitonin.
5.
6.
7.
8. Thyroid Hormones
Thyroid gland secretes three hormones:
1. Tetraiodothyronine / T4 / Thyroxine
2. Tri-iodothyronine / T3
3. Calcitonin
T4 is otherwise known as thyroxine and it forms
about 90% of the total secretion
Whereas T3 is only 9% to 10%
9. Chemistry
Both T4 and T3 are iodine-containing derivatives of
amino acid tyrosine.
10. Potency and Duration of Action
T3 is four times more potent than that of T4.
T4 acts for longer period than T3.
Duration of T4 action is four times more than T3
action.
This is because of the difference in the affinity of
these hormones to plasma proteins.
T3 has less affinity for plasma proteins and combines
loosely with them, so that it is released quickly.
11. T4 has more affinity and strongly binds with plasma
proteins, so that it is released slowly.
Therefore, T3 acts on the target cells immediately
and T4 acts slowly.
12. Half-life
Thyroid hormones have long half-life.
T4 has a long halflife of 7 days.
Half-life of T3 is varying between 10 and 24 hours.
13. Rate of Secretion
Thyroxine = 80 to 90 μg/day
Tri-iodothyronine = 4 to 5 μg/day
Reverse T3 = 1 to 2 μg/day.
14. Metabolism of Thyroid Hormones
Degradation of thyroid hormones occurs in muscles,
liver and kidney.
16. Synthesis of thyroid hormones occurs in five
stages:
1. Thyroglobulin synthesis
2. Iodide trapping
3. Oxidation of iodide
4. Transport of iodine into follicular cavity
5. Iodination of tyrosine
6. Coupling reactions.
17. 1. Thyroglobulin Synthesis
Thyroglobulin molecule is a large glycoprotein
containing 140 molecules of amino acid tyrosine.
Endoplasmic reticulum and Golgi apparatus in the
follicular cells of thyroid gland synthesize and
secrete thyroglobulin continuously.
After synthesis, thyroglobulin is stored in the follicle.
18. 2. Iodide Trapping
Iodide is actively transported from blood into
follicular cell, against electrochemical gradient.
Iodide is transported into the follicular cell along
with sodium by sodium-iodide symport pump, which
is also called iodide pump.
Normally, iodide is 30 times more concentrated in
the thyroid gland than in the blood.
19. 3. Oxidation of Iodide
Iodide must be oxidized to elementary iodine,
because only iodine is capable of combining with
tyrosine to form thyroid hormones.
The oxidation of iodide into iodine occurs inside the
follicular cells in the presence of thyroid peroxidase.
Absence or inactivity of this enzyme stops the
synthesis of thyroid hormones.
20. 4. Transport of Iodine into Follicular Cavity
From the follicular cells, iodine is transported into the
follicular cavity by an iodide-chloride pump also
called pendrin.
21. 5. Iodination of Tyrosine
Combination of iodine with tyrosine is known as
iodination.
It takes place in thyroglobulin.
First, iodine is transported from follicular cells into the
follicular cavity, where it binds with thyroglobulin.
This process is called organification of thyroglobulin.
Then, iodine (I) combines with tyrosine, which is
already present in thyroglobulin
22. Iodination process is accelerated by the enzyme
iodinase, which is secreted by follicular cells.
Iodination of tyrosine occurs in several stages.
Tyrosine is iodized first into monoiodotyrosine (MIT) and
later into di-iodotyrosine (DIT).
MIT and DIT are called the iodotyrosine residues
23. Coupling Reactions
Iodotyrosine residues get coupled with one another.
The coupling occurs in different configurations, to
give rise to different thyroid hormones.
24. Coupling Reaction
One molecule of DIT and one
molecule of MIT combine to
form tri-iodothyronine (T3)
Sometimes one molecule of
MIT and one molecule of DIT
combine to produce another
form of T3 called reverse T3 or
rT3.
Reverse T3 is only 1% of
thyroid output
Two molecules of DIT
combine to form
tetraiodothyronine (T4),
which is thyroxine.
Tyrosine + I =
Monoiodotyrosine (MIT)
MIT + I = Di-iodotyrosine
(DIT)
DIT + MIT = Tri-
iodothyronine (T3)
MIT + DIT = Reverse T3
DIT + DIT =
Tetraiodothyronine or
Thyroxine (T4)
25. Tyrosine + I = Monoiodotyrosine (MIT)
MIT + I = Di-iodotyrosine (DIT)
DIT + MIT = Tri-iodothyronine (T3)
MIT + DIT = Reverse T3
DIT + DIT = Tetraiodothyronine or Thyroxine (T4)
26.
27.
28.
29.
30.
31. Storage Of Thyroid Hormones
After synthesis, the thyroid hormones remain in the
form of vesicles within thyroglobulin and are stored
for long period.
Each thyroglobulin molecule contains 5 or 6
molecules of thyroxine.
There is also an average of 1 tri-iodothyronine
molecule for every 10 molecules of thyroxine.
In combination with thyroglobulin, the thyroid
hormones can be stored for several months.
32. Thyroid gland is unique in this, as it is the only
endocrine gland that can store its hormones for a
long period of about 4 months.
So, when the synthesis of thyroid hormone stops, the
signs and symptoms of deficiency do not appear
for about 4 months.
33. Release Of Thyroid Hormones From The Thyroid
Gland
Thyroglobulin itself is not released into the
bloodstream.
On the other hand, the hormones are first cleaved
from thyroglobulin and released into the blood.
34. Sequence of Events
1. Follicular cell sends foot-like extensions called
pseudopods, which close around the thyroglobulin
hormone complex.
2. This process is mediated by a receptor-like
substance called megalin, which is present in the
membrane of follicular cell
3. Pseudopods convert thyroglobulin-hormone
complex into small pinocytic vesicles
4. Then, lysosomes of the cell fuse with these vesicles
35. 5. Digestive enzymes such as proteinases present in
lysosomes digest (proteolysis) the thyroglobulin and
release the hormones
6. Now, the hormones diffuse through base of the
follicular cell and enter the capillaries
36.
37.
38. MIT and DIT are not released into blood.
These iodotyrosine residues are deiodinated by an
enzyme called iodotyrosine deiodinase, resulting in
the release of iodine.
The iodine is reutilized by the follicular cells for
further synthesis of thyroid hormones.
During congenital absence of iodotyrosine
deiodinase, MIT and DIT are excreted in urine and
the symptoms of iodine deficiency develop.
39. Transport Of Thyroid Hormones In The Blood
Thyroid hormones are transported in the blood by
three types of proteins:
Thyroxine-binding globulin (TBG)
Thyroxine-binding pre-albumin (TBPA)
Albumin
40. Thyroxine-binding Globulin (TBG)
Thyroxine-binding globulin is a glycoprotein and its
concentration in the blood is 1 to 1.5 mg/dL.
It has a great affinity for thyroxine and about one
third of the hormone combines strongly with this
protein
41. Thyroxine-binding Pre-albumin (TBPA)
TBPA transports one fourth of the thyroid hormones.
It is also called transthyretin (TTR).