- 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.
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,
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.
a brief on thyroid gland covering following titles:
Introduction
Anatomy and physiology of thyroid gland
Synthesis of thyroid hormones
Regulation
Mechanism of action
Biological function
A power point presentation on thyroid hormones and thyroid inhibitors on subject of pharmacology suitable for reading by undergraduate medical students.
Parathyroid hormone by Dr. Amruta Nitin Kumbhar, Asst. Professor Dept. of Phy...Physiology Dept
FUNCTIONAL ANATOMY OF PARATHYROID GLANDS
Histological structure
STRUCTURE, SYNTHESIS AND SECRETION OF PTH
REGULATION OF PTH SECRETION
MECHANISM OF ACTION AND ACTIONS OF PTH
Applied physiology
Enter cell by diffusion, active transport, reach
endoplasmic reticulum where T4- T3
Intracellular T3 acts on specific nuclear receptors
(members of c-erbA superfamily)
Thyroid hormones are essential for normal growth of
tissues, including the nervous system.
Lack of thyroid hormone during development results in
short stature and mental deficits (cretinism).
Thyroid hormone stimulates basal metabolic rate
Second ppt on endocrine system, describing hypothalamus, pituitary and thyroid glands.
This describes the hormones from these glands and their mode of action etc
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.
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.
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.
a brief on thyroid gland covering following titles:
Introduction
Anatomy and physiology of thyroid gland
Synthesis of thyroid hormones
Regulation
Mechanism of action
Biological function
A power point presentation on thyroid hormones and thyroid inhibitors on subject of pharmacology suitable for reading by undergraduate medical students.
Parathyroid hormone by Dr. Amruta Nitin Kumbhar, Asst. Professor Dept. of Phy...Physiology Dept
FUNCTIONAL ANATOMY OF PARATHYROID GLANDS
Histological structure
STRUCTURE, SYNTHESIS AND SECRETION OF PTH
REGULATION OF PTH SECRETION
MECHANISM OF ACTION AND ACTIONS OF PTH
Applied physiology
Enter cell by diffusion, active transport, reach
endoplasmic reticulum where T4- T3
Intracellular T3 acts on specific nuclear receptors
(members of c-erbA superfamily)
Thyroid hormones are essential for normal growth of
tissues, including the nervous system.
Lack of thyroid hormone during development results in
short stature and mental deficits (cretinism).
Thyroid hormone stimulates basal metabolic rate
Second ppt on endocrine system, describing hypothalamus, pituitary and thyroid glands.
This describes the hormones from these glands and their mode of action etc
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.
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.
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).
astigmatism
AstigmatismAstigmatism Walter Huang, ODWalter Huang, OD Yuanpei UniversityYuanpei University Department of OptometryDepartment of Optometry
2. DefinitionDefinition When parallel rays of light enter the eyeWhen parallel rays of light enter the eye ((with accommodation relaxedwith accommodation relaxed) and do) and do notnot come to a single point focus on or nearcome to a single point focus on or near the retinathe retina
3. OpticsOptics Power in thePower in the horizontalhorizontal plane projects aplane projects a verticalvertical focal line imagefocal line image Power in thePower in the verticalvertical plane projects aplane projects a horizontalhorizontal focal line imagefocal line image
4. OpticsOptics Refraction of light taking place at a toricRefraction of light taking place at a toric surface: the conoid of Sturmsurface: the conoid of Sturm
TONOMETRY • Tonometry is the procedure performed to determine the intraocular pressure (IOP).
3. CLASSIFICATION TONOMETRY DIRECT INDIRECT Indentation Applanation Manometer
4. APPLANATION Contact Non-contact Goldmann Perkins Air-puff Pulse air
5. INDENTATION TONOMETER • It is based on fundamental fact that plunger will indent a soft eye more than hard eye. • The indentation tonometer in current use is that of Schiotz . • It was devised in 1905 and continued to refine it through 1927.
6. PROCEDURE • Patient should be anaesthetising with 4% lignocaine or 0.5% proparacaine. • with the patient in supine position, looking up at a fixation target while examiners separates the lids and lower the tonometer plate to rest on the cornea so that plunger is free to move. •
. Introduction Biomicroscope derives its name from the fact that it enables the practitioner to observe the living tissue of eye under magnification. It not only provides magnified view of every part of eye but also allows quantitative measurements and photography of every part for documentation.
3. • The lamp facilitates an examination which looks at anterior segment, or frontal structures, of the human eye, which includes the –Eyelid –Cornea –Sclera –Conjunctiva –Iris –Aqueous –Natural crystalline lens and –Anterior vitreous.
4. Important historical landmarks De Wecker 1863 devised a portable ophthalmomicroscope . Albert and Greenough 1891,developed a binocular microscope which provided stereoscopic view. Gullstrand ,1911 introduced the illumination system which had for the first time a slit diapharm in it Therefore Gullstrand is credited with the invention of slit lamp.
1. Introduction Gross anatomy Layers Blood supply, drainage and nerve supply
2. INTRODUCTION • Sclera forms posterior 5/6th of external tunic , connective tissue coat of eyeball. • it continues with duramater and cornea • Its whole surface covered by tenon’s capsule • Anteriorly covered by- bulbar conjunctiva • Inner surface lies in contact with choroid • With a potential suprachoroidal space in between
3. Equa THICKNESS OF SCLERA
4. • Thickness varies with individual, with age • Thinner- children, elder, F> M • Thickest posteriorly • Gradually becomes thinner when traced anteriorly • Thin at insertion of extraocular muscle
The pupil is an opening located in the center of the iris that allows light to enter the retina. • Its function is to control the amount of light entering the eye and it does this via contraction (miosis) and dilation (mydriasis) under the influence of the autonomic nervous system
3. • The iris is a contractile structure, consisting mainly of smooth muscle, surrounding the pupil. Light enters the eye through the pupil, and the iris regulates the amount of light by controlling the size of the pupil.
4. The iris contains two groups of smooth muscles: a circular group called the sphincter pupillae. and a radial group called the dilator pupillae.
5. Parasympathetic pathway • First Order – Retina to Pretectal Nucleus in B/S (at level of Superior colliculus) Second Order – Pretectal nucleus to E/W nucleus (bilateral innervation!) Third Order – E/W nucleus to Ciliary Ganglion Fourth Order – Ciliary Ganglion to Sphincter pupillae (via short ciliary nerves) • • •
The tear film constitutes Three layers :- An outermost lipid (oily) layer An aqueous (watery) layer that makes up 90% of the tear film volume; and A mucin layer that coats the corneal surface.
3. To form smooth optical surface on cornea. To keep the surface of cornea & conjunctiva moist It serve as lubricant It transfer oxygen Provide antibacterial action Wash debris out It provides a pathway for WBC in case of injury
4. Functions of lipid layer Retards evaporation of tear film Prevents the overflow of tears
5. Function of Aqueous Layer Flushes, buffers and lubricates the corneal surface Delivers oxygen and other nutrients to the corneal surface Wash out debris Delivers antibacterial enzymes and antibodies such as lysozyme.
6. Functions of Mucin Layer Spreads tears over corneal surface. Protects the cornea against foreign substances . Makes corneal surface smooth by filling in surface irregularities
Introduction Transparent,avascular,watch-glass like structure. Forms 1/6th part of outer fibrous coat (Sclera) It is the major refracting surface of the eye
3. Dimensions + Avg horizontal dia =11.75 mm (ant surface) + Avg vertical dia = 11 mm (ant surface ) + Avg dia (post surface)= 11.5 mm + Thickness(centre) =0.52mm + Thickness(peripheral) = 0.67mm + Radius of curvature (ant surface) = 7.8mm + Radius of curvature (post surface)= 6.5mm + Refractive power (ant surface) = +48D + Refractive power(post surface)= - 5D + R.I = 1.376
4. Histology + Epithelium + Bowman’s membrane + Stroma + Dua’s layer + Descemet’s membrane + Endothelium
5. Epithelium + Made up of stratified squamous epithelium + Thickness - 50-90 um + 5-6 layers of cells + Regenerative, entire epithelial layer is replaced every 6-8 days + Made up of 3 types of cells - basal,wing, flattened cells + Cells are attached by to each other by means of desmosomes & maculi occludents
6. Bowman’s membrane + Acellular,Non regenerative + Made up of condensed collagen fibrils. + Thickness - 12um + Resistant to infection & injury.
LIMBUS… • The limbus forms the border between the transparent cornea and opaque sclera, contains the pathways of aqueous humour outflow, and is the site of surgical incisions for cataract and glaucoma
2. Anatomical Limbus: Circumcorneal transitional zone of the conjunctivocorneal & corneoscleral junction Conjunctivo-corneal junction: • Bulbar conjunctiva is firmly adherent to underlying structures • Substantia propria of the conjunctiva stops here but its epithelium continues with that of the cornea. Sclero-corneal junction: • Transparent corneal lamellae become continuous • With the oblique, circular and opaque fibres of sclera
3. CONTINUE…. • In the area near limbus, the conjunctiva, tenon’s capsule & the episcleral tissue are fused into a dense tissue which is strongly adherent to corneo scleral junction.It is preferred site for obtaining a firm hold of the eyeball during ocular surgery. • The limbus is a common site for the occurrence of corneal epithelial neoplasm. • The Limbus contains radially oriented fibrovascular ridge known as the palisades of Vogt that may harbour a stem cell population. The palisades of Vogt are more common in the superior and inferior quadrants around the eye
Diagnosis, Management, and Surgery by Adam J. Cohen, Michael Mercandetti & Brian G. Brazzo. The dry eye , a practical approach by Sudi Patel & Kenny J Blades. Jack J Kanski’s clinical ophthalmology Clinical Anatomy of the Eye by Richard S. Snell & Michael A. Lemp.
3. It is concerned with the tear formation & transport. Lacrimal passage includes : Lacrimal gland Conjunctival sac Lacrimal puncta Lacrimal canaliculi Lacrimal sac Nasolacrimal duct
4. The following components of the lacrimal apparatus are discussed : Embryology Osteology Secretory system Excretory system Physiology
5. Ectodermal origin Solid epithelial buds(first 2 months) Supero
Extraocular musles(EOM) They are six in number Four recti: Superior rectus Inferior rectus Medial rectus Lateral rectus Two oblique muscles: Superior oblique Inferior oblique
3. SUPERIOR RECTUS MUSCLE . Origin Superior part of common annular tendon of Zinn Course Passes anterolaterally beneath the levator At 23 degrees with the globe ‘s AP axis Pierces Tenon s capsule Insertion into sclera by flat tendinous 10 mm broad insertion 7.7 mm behind sclero-corneal junction. 42 mm long 9 mm wide
4. Nerve supply Sup division of 3rd N Blood Supply Lateral Muscular br. of Ophthalmic A APPLIED: SR loosely bound to LPS muscle. • During SR resection- eyelid may be pulled forward narr owing palpebral fissure • In hypotropia pseudoptosis may be present Origin of SR and MR are closely attached to the dural sheat h of the optic nerve pain during upward & inward movements of the globe in RETROBULBAR NEURITIS
Diseases of sclera
2. anatomy • Sclera posterior 5/6th opaque part of the external fibrous tunic of the eyeball.
3. • outer surface }covered by Tenon's capsule. • anterior part } covered by bulbar conjunctiva.
4. Its inner surface lies in contact with choroid with a potential suprachoroidal space in between
5. Thickness of sclera. • thinner }children and in females Sclera • thickest} posteriorly (1mm) • gradually becomes thin when traced anteriorly. • thinnest } insertion of extraocular muscles (0.3 mm). • Lamina cribrosa is a sieve-like sclera from which fibres of optic nerve pass.
6. Apertures of sclera • Anterior • Anterior ciliary vessels • Middle • four vortex veins (vena verticosae) • Posterior • Optic nerve • Long & short ciliary nerves
7. Layers of sclera sclera episclera Sclera proper Lamina fusca thin, dense vascularised layer of connective tissue fibroblasts, macrophages and lymphocytes avascular structure dense bundles of collagen fibres. innermost blends with suprachoroidal and supraciliary laminae of the uveal tract. brownish in colour presence of pigmented cells.
Main physiologic function of cornea is to act as a major refracting medium, so that a clear retinal image is formed. • Normal corneal transparency is result of • 1.anatomical factor such as uniform and regular arrangement of corneal epithelium, peculiar arrangement of corneal lamella and corneal vascularity 2.Physiological factor [ie] relative state of corneal dehydration.
3. • Therefore, any process which upsets the anatomy or physiology of cornea will cause LOSS OF TRANSPARENCY to some degree.
4. FACTORS AFFECTING CORNEAL TRANSPARENCY • CORNEAL EPITHELIUM &TEAR FLIM • ARRANGEMENT OF STROMAL LAMELLA • CORNEAL VASCULARIZATION • CORNEAL HYDRATION • CELLULAR FACTORS AFFECTING TRANSPARENCY
CONJUNCTIVA: ANATOMY , PHYSIOLOGY, SYMPTOMATOLOGY AND CLASSIFICATION Pranay Shinde DNB Resident Deen Dayal Upadhyay Hospital,New Delhi
2. ANATOMY It is the mucous membrane covering the under surface of the lids and anterior part of the eyeball upto the cornea.
3. Parts of conjunctiva • Palpebral; covering the lids—firmly adherent. • Forniceal; covering the fornices—loose—thrown into folds. • Bulbar; covering the eyeball—loosely attached except at limbus.
4. Palpebral conjunctiva • Subtarsal sulcus 2mm from posterior edge of the lid margin. • Richly vascular. • Extremely thin. • Strongly bound to the tarsal plate.
5. Palpebral conjunctiva is subdivided into three parts: 1)Marginal 2)Tarsal 3)Orbital
6. Conjunctival fornices • Transitional region between palpebral and bulbar conjunctivae. • Superior fornix 10 mm from limbus. • Inferior fornix 8 mm from limbus. • Lateral fornix 14mm from limbus. • Medially absent. • Ducts of lacrimal glands open into lateral part of superior fornix.
q Colour Vision Deficiency Presented by : Optometrist (intern) Asma Al-Jroudi Saudi Arabia, Riyadh, King Abdulaziz University Hospital 30 Dec 14
2. • What Is Color Vision Deficiency? • Causes Of Color Vision Deficiency • Types Of Color Vision Deficiency • Tretments Of Color Vision Deficiency • Ishihara’s Test • Conclousion
3. What is Colour Blindness? • Color blindness, or color vision deficiency, is the inability or decreased ability to see color, or perceive color differences, under normal lighting conditions. •This condition results from an absence of color- sensitive pigment in the cone cells of the retina, the nerve layer at the back of the eye.
4. What is Colour Blindness? • Cones are the coulored light receptors in back of the eye: Red light receptors, Blue light receptors and Green light receptors. • Colour blindness occurs when one or more of the cone types are defected.
5. Causes of Color Blindness • Genetic: Many more men are affected than women. • Acquired : Chronic illness, Accidents, Medications and Age.
ANATOMY & PHYSIOLOGY Lecturer: Tatyana V. Ryazantseva
2. Outer eye: Eyelids The eyelids fulfill two main functions: protection of the eyeball secretion, distribution and drainage of tears
3. Lid movement The levator extends from an attachment at the orbital apex to attachments at the tarsal plate and skin. ● The lids are securely attached at either end to the bony orbital margin by the medial and lateral palpebral ligaments. Trauma to the medial ligament causes the lid to flop forward and laterally, impairing function and cosmesis.
4. Innervation - Sensory innervation is from the trigeminal (fifth) cranial nerve, via the ophthalmic division (upper lid) and maxillary division (lower lid). - The orbicularis oculi is innervated by the facial (seventh) nerve. - The levator muscle in the upper lid is supplied by the oculomotor (third) nerve.
5. Blood supply and lymphatics The eyelids are supplied by an extensive network of blood vessels which form an anastomosis between branches derived from the external carotid artery via the face and from the internal carotid artery via the orbit.
6. Blood supply and lymphatics Lymphatic fluid drains into the preauricular and submandibular nodes. Preauricular lymphadenopathy is a useful sign of infective eyelid swelling (especially viral).
Anatomy and Physiology of Aqueous Humor Sumit Singh Maharjan
2. Anatomy
3. Angle of anterior chamber
4. Angle of the Anterior chamber
5. Gonioscopic grading of Angle
6. Aqueous Outflow system
7. Trabecular meshwork
8. Functions of Aqueous Humor • Maintenance of Intraocular pressure • Metabolic role cornea lens vitreous and retina • Optical function • Clearing function
9. Physicochemical properties • volume: 0.31ml (0.25ml in Ant. Chamber and 0.06 in post chamber) • Refractive index: 1.336 • Density: slightly greater than water, its viscocity is 1.025-1.040 • Osmotic pressure: slightly hyperosmotic to plasma by 3-5mosm/l • PH: 7.2 • Rate of formation: 2-2.5microliter/min
10. Biochemical composition • Water: 99.9% • Proteins: 5-16mg/100ml • Amino acids: aqueous/plasma concentration varies from 0.08-3.14 • Non colloidal constituents: conc. of ascorbate, pyruvate, lactate in higher am
Vitreous humour
1. Vitreous Humour
2. General features Vitreous humour is an inert ,transparent , colourless, jellylike, hydrophilic gel that serves the optical functions and also acts as important supporting structures for the eyeball. The vitreous cavity is bounded by anteriorly by the lens and ciliary body and posteriorly by the retina Its weighs nearly 4g Vitreous is an extacellular material composed of approximately 99 per cent water
3. Structure The vitreous body is the largest and simplest connective tissue present as a single piece in the human body Divided into three parts- 1. The hyaloid layer or membrane 2. The cortical vitreous and 3. The medullary vitreous
Vitamins all
1. Vitamins. Definition - Organic compound required in small amounts. Vitamin A Vitamin B1, B2, B3, B5, B6, B7, B9, B12 Vitamin D Vitamin E Vitamin K A few wordsabout each.
2. Sourcesin diet - Many plants(photoreceptors), also meat, especially liver. Fat soluble, so you can get too much, or too littleif absorption isaproblem. Vitamin A - Retinol Retinol (vitamin A) Someuses: Vision (11-cis-retinol bound to rhodopsin detectslight in our eyes). Regulating genetranscription (retinoic acid receptorson cell nuclei arepart of a system for regulating transcription of mRNAsfor anumber of genes).
Tear film
1. TEAR FILM
2. The outer most layer of the cornea. It is the exposed part of the eyeball. FUNCTION It provide smooth optical surface It serves to keep the surface of cornea and conjunctiva moist. It serves as a lubricant for the preocular surface and lids It transfer oxygen from the air to the cornea Prevent infection due to the presence of antibacterial substance like lysozymes,and other protein. It wash away debris and irritants Provides pathway to WBC in case of injury.
3. LAYERS OF TEAR FILM It consist of three layers: 1.Lipid layer 2.Aqueous layer 3.Mucoid layer 1.LIPID LAYER
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
2. Case History
A fit 32-year-old man presents with a lump
low in the left side of his neck. He first
noticed it four weeks ago. He has no other
relevant personal or family history.
Examination shows a 3 cm hard, mobile
swelling on the front of the neck. The
swelling moves when he swallows.
3. THYROID:
a historical
perspective
•Goitre & mountains:
Goitre was first seen in inhabitants
of Alps. Initially they did not know
that goitre is enlargement of
thyroid gland. It was then
documented that consuming sea
weeds caused remarkable
reduction of the swelling in these
patients. It was later discovered
that sea weeds contain large
amounts of iodine.
•1619:
Thyroid enlargement was first
described as a cause of swelling
on the front of the neck. It was also
clearly noted that this swelling
moved up and down when the
patient attempts to swallow.
5. THE THYROID
GLAND
- 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 of
the 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.
7. THYROID
GLAND
The thyroid gland
consists of 2 types of
cells:
1. Follicular cells:
These are more
abundant, and the
major secretory
cells. They secrete
Thyroid hormone.
2. Parafollicular
cells or C-cells:
These are fewer in
number &
interspersed. They
secrete Calcitonin.
8. THYROID GLAND AS A
FUNCTIONAL UNIT
- The functional unit of the
Thyroid Gland is a Follicle
(acinus) which is
composed of cuboidal
epithelial (follicular) cells
arranged around hollow
vesicles of various shapes
(size: 0.02-0.3 mm in
diameter).
- Arrangement is such
that each follicular epithelial
cell lies adjacent to a
capillary!
- Each follicle is a closed
structure filled with a
glycoprotein colloid called
Thyroglobulin. It is a
proteinaceous material.
- There are about 3 million
follicles in an adult human
thyroid gland.
10. THYROID HORMONES
• The Thyroid gland secretes 3 major
hormones:
1. Thyroxine or T4 : having 4 atoms of
Iodine. (secreted in largest amount)
2. Triiodothyronine or T3 : having 3 atoms
of Iodine (secreted in lesser amount)
3. Reverse T3 also called RT3. (secreted in
the least amount)
4. Calcitonin: which is an important
hormone of calcium metabolism.
11.
12. THYROID HORMONES
• About 93% of secreted hormone is T4, while
7% is T3. However, almost all T4 is
ultimately converted into T3.
• The functions of the 2 hormones are the
SAME but they differ in rapidity & intensity
of action.
• T3 is about 4 times as potent as T4, and has
a much greater biological activity but is
present in blood in much smaller
quantities & for a much shorter time!
• RT3 is NOT biologically active.
14. POINTS TO REMEMBER:
1. Iodine in large amounts is required for thyroid hormone
synthesis. This is acquired through diet & THERE IS NO
OTHER USE OF THIS ELEMENT IN THE BODY!
2. The hormones are synthesized in the lumen of the follicular
epithelial cells & then stored in the colloid of the follicle.
3. The hormone is thus doubly secreted: once from the
follicular cell into the follicular lumen where it is stored and
then reuptaken by the follicular cells where thyroglobulin is
degraded & the released T3 & T4 are again secreted into the
blood.
4. The Follicular cell has 2 surfaces: a basolateral surface
facing the blood capillaries & the ECF, & an apical surface
facing the follicular lumen containing the colloid.
5. Thyroxine, the major secretory product, is not the
biologically active form but must be converted into T3 at
extrathyroidal sites to exert potent effects.
16. INGESTION OF IODINE
• 50 mg of Iodine is required each year OR
1 mg/week OR 150 µg/ day.
• To prevent deficiency, common table salt
is iodized with about 1 part sodium iodide
to every 100,000 parts sodium chloride.
• Ingested iodide is absorbed from the
intestines and enters the circulation.
17. IODIDE TRAPPING
Under normal circumstances, iodine is 25-50 times more
concentrated in the cytosol of Thyroid follicular cells than
in the blood plasma.
↓
Thus, iodine moves into the thyroid cells against a steep
concentration gradient!
↓
This is done with the help of an elctrogenic “Iodide pump”
also called the “NIS or Sodium Iodide Symporter”
located in the thyroid cell membrane.
The process involved is Secondary Active Transport and
the energy is provided by the concentration gradient
maintained by the Sodium Potassium Pump.
18. NA/I SYMPORTER
This pump, thus, transfers 2 Na ions for each Iodide ion.
↓
The role of the SODIUM POTASSIUM PUMP is very important as it then extrudes 3 Na ions in
exchange for 2 K ions to maintain the electrochemical gradient for Na.
19. Is it the Iodine or the Iodide that
is absorbed from the intestines?
• Dietary iodine is reduced to iodide before
absorption by the small intestine.
• It is the IODIDE form of Iodine that takes
part in the various steps of thyroid
hormone biosynthesis.
• In addition to Iodine, Tyrosine is essential
for TH synthesis. Tyrosine is found as part
of the Thyroglobulin.
20. THYROGLOBULIN SYNTHESIS
• It is the matrix for thyroid hormone synthesis & is the
form in which the hormone is stored in the gland.
• It is a large glycoprotein with about 140 molecules of
tyrosine and a m.w of 660,000 Da.
Synthesized on ribosomes
↓
Glycosylated in the ER
↓
Packaged in the secretory vesicles
↓
Secreted by exocytosis into the colloid of the thyroid
follicle
21. THYROGLOBULIN
SYNTHESIS
The amino acid Tyrosine
becomes incorporated
into the much larger
Thyroglobulin while it is
being produced
↓
Iodination to form the
mature hormone will
take place once the
thyroglobulin is secreted
into the colloid.
22. Transport of Iodine into the
follicular lumen!
• For hormone synthesis to take place, Iodide must
be delivered to the follicular lumen.
• The Iodide that has entered into the follicular cell
from the blood stream must exit the follicular cell
across the apical membrane to access the colloid,
where the initial steps of hormone synthesis occur.
• This is done with the help of a Chloride- Iodide
exchanger known as PENDRIN.
• PENDRIN is protein which is an anion exchanger.
23. POINTS TO REMEMBER:
• Tyrosine-containing Thyroglobulin is
transported from the follicular cells into the
colloid by exocytosis.
• Iodine is transferred into the Colloid!
24. OXIDATION OF THE IODIDE ION
• Iodide ion is oxidized to form either
nascent iodine (I°) or I3− .
• This oxidation is catalyzed by the enzyme
thyroperoxidase/ peroxidase and its
accompanying hydrogen peroxidase.
• These enzymes are located in the apical
membrane of the cell.
25. ORGANIFICATION
• Addition of iodide molecules to tyrosine
residues in the thyroglobulin is called
Organification of thyroglobulin.
• This reaction is catalyzed by the enzyme
Iodinase.
• Tyrosine + 1 Iodine = Monoiodotyrosine
(MIT)
• Tyrosine + 2 Iodines = Di-iodotyrosine
(DIT)
26. COUPLING
• It is the combination or coupling of 2 molecules of
iodinated tyrosine molecules to form thyroid
hormone:
- DIT + DIT = Thyroxine (T4)
- DIT + MIT = Tri-iodothyronine (T3)
COUPLING DOES NOT OCCUR B/W 2 MIT
MOLECULES!
This mature hormone is formed while a part of
Thyroglobulin molecule, & remains a part of this
large storage molecule till the stimulus for
secretion arrives.
27. STORAGE
In normal individuals, approximately 30% of
the mass of thyroid gland is thyroglobulin,
which is about 2-3 months supply of
hormone.
28. SECRETION
• For secretion to occur, thyroglobulin must be
brought back into follicular cells by a process of
endocytosis.
• Pseudopodia reach out from the follicular cells to
engulf chunks of thyroglobulin, which are taken
up in endocytic vesicles- this is also called
“BITING OFF”.
↓
On appropriate stimulation for thyroid secretion,
the follicular cells internalize a portion of
thyroglobulin- hormone complex by
phagocytozing a piece of colloid
29. SECRETION
The endocytic vesicles fuse with the lysosomes
↓
Lysosomes release enzymes that split off the
biologically active hormones: T3 & T4, as well as
the inactive iodotyrosine, MIT & DIT.
↓
The thyroid hormones being very lipophilic, pass
freely through the outer membrane of the
follicular cells & into the blood!
30. FATE OF MIT & DIT
The MIT & DIT are of no endocrine value.
↓
The follicular cells contain an enzyme
(deiodinase) that will swiftly remove the
Iodide from MIT & DIT, allowing the freed
Iodide to be recycled for synthesis of more
hormone.
What is the significance of the enzyme
DEIODINASE?
31.
32.
33. PASSAGE THROUGH BLOOD
This highly lipophilic thyroid hormone molecule
binds with several plasma proteins.
• The binding proteins are:
1.Thyroxine binding globulin (TBG) (binds 70% of
the hormone)
2.Transthyretin (TTR)(binds 15% of the hormone)
3.Albumin (binds 15% of the hormone)
The majority bind to TBG, a plasma protein that
selectively binds only Thyroid hormone.
Why is the TH transported in the bound form?
34. Significance of the Bound hormone:
• Normally 99.98% of the T4 in plasma is bound.
• Less than 0.1% of T4 and less than 1% of T3 is in the unbound (free)
form.
• T3 has less affinity for the plasma proteins and binds loosely with
them, so that it releases quickly. T4 has more affinity and binds
strongly with them so that it is released slowly. Therefore, T3 acts on
the target cells immediately and T4 acts slowly.
• These binding proteins are synthesized by the liver. Any disease of
the liver will thus have an indirect effect on the amount of Total free
hormone levels.
• When a sudden, sustained increase in the thyroid binding proteins
in the plasma takes place, the concentration of free hormone falls.
This is, however, corrected over time.
• TBG levels are increased by estrogen therapy and in pregnancy
while it is depressed by glucocorticoids, androgens and several
chemotherapeutic drugs.
35. Rate of Secretion & Plasma Levels
Rate of Secretion:
Total T4 : 80-90 µg/ day
Total T3 : 4-5 µg/ day
Reverse T3 : 1-2 µg/ day
Plasma Levels:
Total T3 : 0.12 µg/ dl
Total T4 : 8µg/ day
36. METABOLISM
• The thyroid hormones are deiodinated in the
liver, the kidneys and many other tissues.
The T4 is converted intoT3 by being stripped
of one of its Iodides.
• T4 has a long half-life of: 7 days
• T3 has a half-life of: upto 1 day
• Prolonged latent period for T4: action starts to
show almost 2-3 days after release & may
persist for as long as 6 weeks to 12 months.
• Shorter latent period for T3: starts showing its
effects within 6- 12 hours & maximal cellular
activity occurs within 2-3 days.
38. M.O.A
• Thyroid hormone receptors are members
of a large family of nuclear hormone
receptors
Location: Thyroid hormone receptors are
either attached to the DNA genetic strands
or located in close proximity to them.
39. M.O.A
The thyroid receptor binds to hormone receptor element on the DNA either as a
heterodimer with retinoid X receptor (RXR) or a homodimer.
(The TR/ RXR is the most transcriptionally active form of the receptor.)
↓
In the absence of the hormone, the thyroid hormone receptor binds to their
response elements.
↓
When the thyroid hormone becomes available, the receptor becomes activated
& initiates the transcription process.
↓
Large number of mRNA are formed
↓
Within minutes or hours: RNA translation on the cytoplasmic ribosomes
↓
Hundreds of new intracellular proteins are formed
↓
Most of the actions are exerted through these proteins
Editor's Notes
Trace elements are elements that occur in very small amounts in living organisms and are necessary for their health, growth and development. Whereas their shortage in the body may result in stunted growth and disease, their excess is also harmful. If deficient they need to be taken with diet.
It looks like a bow tie & is even located in the appropriate place for a bow tie lying over the trachea just below the larynx! It develops from an evagination of the floor of the pharynx, and a thyroglossal duct marking the path of the thyroid from the tongue to the neck sometimes persists in the adult.
These 2 secretory cells are derived embryologically from 2 different sources: Follicular cells from endoderm of primitive pharynx & C-cells from neuroectoderm.
When the gland is inactive, the colloid is abundant, the follicles are large, and the cells lining them are flat. When the gland is active, the follicles are small, and the cells are cuboid or columnar.
Iodide is thus transported against its concentration gradient driven by the favorable electrochemical gradient for sodium! Energy is then expended by the Na/ K ATPase ( the sodium pump). Outward diffusion of k maintains the membrane potential.
Like other transporters, Na-I symporter has a finite capacity & can be saturated. Consequently, other ions as perchlorate & thiocyanate compete for binding sites on the symporter, can block the uptake of iodide. This property can be exploited for diagnostic purposes!
This reaction is catalyzed by Thyroperoxidase.
Thyroglobulin stored within the follicular lumen is separated from ECF & the capillary endothelium by a virtually impenetrable layer of follicular cells. It is a complicated process for 2 reasons:
Before their release, T4 & T3 are still bound within the thyroglobulin molecule.
These hormones must be transported completely across the follicular cells to reach the capillaries that course through the interstitial spaces b/w the follicles.
This highly specific enzyme will remove iodine only from the worthless MIT & DIT and not from T3 & T4. Deiodinase provides almost twice as much iodide for hormone synthesis as Iodide pump & is therefore of great significance in hormone biosynthesis. Patients who are genetically deficient in thyroidal tyrosine deiodinase suffer symptoms of iodine deficiency & excrete MIT & DIT in their urine. Normally, virtually no MIT & DIT escapes from the gland.
It is remarkable that such less percentage is carried in free form as it is only the free pool of the hormone that has access to the target organ receptors & thus can exert their effect! Also the bound protein cannot escape the blood stream through the capillary endothelium as it is too large!
The other binding proteins are:
Thyroxine binding globulin (TBG) (binds 70% of the hormone)
Transthyretin (TTR) (binds 15% of hormone)
Albumin (binds 15%)
The bound hormone provides substantial reservoir of extrathyroidal hormone!
Therefore, when there is a deficiency of thyroid hormone due to a defect of the gland, the deficiency is not even noticed for weeks to months as the unbound form is slowly released. Also, the total amount of bound T3 & T4 will be affected if the plasma protein concentration is decreased as with kidney & liver diseases.
Like all lipophilic hormones, TH crosses the cell membrane and binds with an intracellular receptor, which in this case is a nuclear receptor. The thyroid nuclear receptor has a 10 times greater affinity for T3 than for T4. Because a hormone’s potency also depends on how strongly a hormone binds to its receptor therefore T3 is far more potent.