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
Corneal metabolism
1. o Cornea requires energy for normal metabolic activities as well as for maintaining transparency and dehydration o Energy is generated by the breakdown of glucose in the form of ATP o Most actively metabolizing layer are epithelium and endothelium o Sources of nutrients : o Oxygen : mainly from atmosphere through tear film , with minor amount supplied by the aqueous and limbal vasculature o Glucose , amino acid, vitamins and other nutrients supplied to cornea by aqueous humor o Glucose also derived from glycogen stores in corneal epithelium o Epithelium consumes O2 10 times faster then stroma
2. o Three process or pathways – o Pentose shunt (Hexose monophosphate shunt) –occurs both in hypoxic and normoxic condition o Glycolysis (Embden meyerhof pathway) –anaerobic process , glucose / glycogen converted to pyruvate yeilding 2 ATPs o TCA or krebs or citric acid cycle- aerobic condition pyruvate is oxidized to yield 36 ATP, water, CO2.
3. o In normal conditions all the glucose consumed by the cornea o Glucose mostly come from aqueous humor o The rate of glucose consumption by the whole cornea is approx. 100 microgram/hr/cm2. o 1 mol. of glucose will be converted to the pyruvic acid and produced 2 molecules lactic acid and 2 mol. of ATP o In the krebs cycle, 1 mol. of glucose will utilize the pyruvic acid and O2 to produced 36 mol. ATP o Epithelium and endothelium will consume the oxygen
4. o The pentose phosphate pathway is used to metabolize five carbon sugars; one ATP and 2 NADH molecules are produced from oxidation of one glucose molecule o Produced intermediates for nucleic acid synthesis and some amino acids o This process will happen in hypoxic or normoxic condition o The purpose of glucose metabolism through the pentose shunt is the production of NADPH
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
Corneal metabolism
1. o Cornea requires energy for normal metabolic activities as well as for maintaining transparency and dehydration o Energy is generated by the breakdown of glucose in the form of ATP o Most actively metabolizing layer are epithelium and endothelium o Sources of nutrients : o Oxygen : mainly from atmosphere through tear film , with minor amount supplied by the aqueous and limbal vasculature o Glucose , amino acid, vitamins and other nutrients supplied to cornea by aqueous humor o Glucose also derived from glycogen stores in corneal epithelium o Epithelium consumes O2 10 times faster then stroma
2. o Three process or pathways – o Pentose shunt (Hexose monophosphate shunt) –occurs both in hypoxic and normoxic condition o Glycolysis (Embden meyerhof pathway) –anaerobic process , glucose / glycogen converted to pyruvate yeilding 2 ATPs o TCA or krebs or citric acid cycle- aerobic condition pyruvate is oxidized to yield 36 ATP, water, CO2.
3. o In normal conditions all the glucose consumed by the cornea o Glucose mostly come from aqueous humor o The rate of glucose consumption by the whole cornea is approx. 100 microgram/hr/cm2. o 1 mol. of glucose will be converted to the pyruvic acid and produced 2 molecules lactic acid and 2 mol. of ATP o In the krebs cycle, 1 mol. of glucose will utilize the pyruvic acid and O2 to produced 36 mol. ATP o Epithelium and endothelium will consume the oxygen
4. o The pentose phosphate pathway is used to metabolize five carbon sugars; one ATP and 2 NADH molecules are produced from oxidation of one glucose molecule o Produced intermediates for nucleic acid synthesis and some amino acids o This process will happen in hypoxic or normoxic condition o The purpose of glucose metabolism through the pentose shunt is the production of NADPH
anatomical consideration of development of eye from embryonic stage. gives insight into future anatomical and pharmacological basis of drug development in disorders of eye.
The Atlas of the eye is a B.sc. degree research
It contains three parts:
- Anatomy & Physiology of the eye
- Pathology & errors in the eye
- Photography of the eye
enjoy it!
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
How to Split Bills in the Odoo 17 POS ModuleCeline George
Bills have a main role in point of sale procedure. It will help to track sales, handling payments and giving receipts to customers. Bill splitting also has an important role in POS. For example, If some friends come together for dinner and if they want to divide the bill then it is possible by POS bill splitting. This slide will show how to split bills in odoo 17 POS.
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.
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
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.
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.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
2. LENS EMBROLOGY
The development of the eyeball starts around
day 22 of gestation and it is around 2mm in
length.
3. First, a linear thickening develops on either
side of the neural plate which is going to form
the prosencephalon
It becomes depressed to form the optic
sulcus.
Walls of prosencephalon overlying the sulcus
bulge out to form the optic vesicle
Proximal part of the optic vesicle becomes
constricted to form the optic stalk
4.
5. Optic vesicle grows laterally and comes in
relation with the surface ectoderm
At 27th day the overlying surface ectoderm
becomes thickened to form the lens placode
It slowly sinks below the surface and is
converted into lens vesicle
Seperates from the surface at 33rd day.
6.
7.
8. Simultaneously, the optic vesicle gets
converted into optic cup due to differential
growth of its margins
The optic cup surrounds the upper and the
lateral sides of the lens
It is deficient in the inferior part known as the
choroidal or fetal fissure. This closes by 6th
week. Failure to fuse leads to typical
colobomas.
9.
10. The neural tube is surrounded by
mesenchyme which condenses to form the
meninges
The mesenchyme around the optic vesicles
forms 2 layers-
Superficial fibrous layer- sclera and cornea
Deep vascular layer- uvea
Part of the inner vascular layer is carried into
the cup through the fissure. When fissure
closes, it forms the hyaloid vessels
11. The hyaloid vessels suppy the lens in the
fetus due to which it grows rapidly.
Later the hyaloid vessels disintegrate and the
remains forms the central retinal artery and
vein. The lens derives its nutrtion then by
diffusion from the aqeous humor and vitreous
humor.
12.
13.
14. ANATOMY OF THE LENS
Lens is a tranparent, avascular, biconvex
crystalline structure placed between the iris
and vitreous in the patellar fossa
15. It has 2 surfaces- anterior surface and posterior
surface.
These 2 surfaces meet at the equator.
The centre of the anterior and posterior surfaces
are known as anterior and posterior pole
The posterior surface is attached to the vitreous
by Wiegert’s ligament.
Between the lens capsule and the hyaloid face is
a small cavity k.a. retrolental space or berger’s
space.
16. DIMENSIONS--
1. Equatorial diameter- 6.5 mm at birth, 10 mm
in adults
2. AP diameter- 3.5 mm to 5mm
3. Radius of anterior surface- 10mm
4. Radius of posterior surface- 6 mm
5. Wieght- 150 mg- 250 mg
17. Refractive index- 1.38 ( cortex)
1.42 ( nucleus)
Refractive power- 16-17 D
Accomodative power- 14-16 D at birth
7-8 D at 25 yrs
1-2 D at 50 yrs
19. Lens capsule
It is a thin , transparent elastic membrane which
surrounds lens completely
Secreted by basal cells of anterior lens epithelium
and basal area of elongating fibres posteriorly.
Thicker anteriorly than posteriorly
Thicker at the equator than the poles, thinnest at
the posterior poles
20. It is made up of type 4 collagen and 10%
glycosaminoglycans
21. Anterior lens epithelium
Single layer of cuboidal nucleated epithelial
cells.
Cells contain all the organelles found in a
normal epithelial cell since all the metabolic,
synthetic and transport processes of lens
occur in this layer
22. 3 zones
Central- cuboidal cells which reduce with
age. Do not mitose normally.
Can undergo mitosis in response to injury like
in uveitis.
Metaplasia of these cells into spindle shaped
myofibroblast like cells can lead to ASC- eg.
Shield cataract in atopic dermatitis,
Glaucomflecken after ACG
23. Intermediate zone
Smaller and more cylindrical.
Undergo mitosis occasionally
Germinative zone
Columnar cells located pre- equatorially.
Actively dividing to form new cells which
migrate posteriorly to become lens fibres.
Extremely susceptible to radiation
Dysplasia can lead to PSC in radiation
exposure, myotonic dystrophy and NF-2.
24. Lens fibres
Form the main bulk of the lens. They are long
thin transparent cells firmly packed with
diameter of 4-7 micron and length upto
12mm
The cells of the newly formed fibres contain
all the organelles and as the fibres mature the
nucleas disappears.
25. The cells are linked by gap junctions and
interdigitations that look like ball and socket.
These are fewer in the superficial fibres.
26. FORMATION OF LENS FIBRES
EARLY LENS VESICLE-
consists of a single
layer of cells covered
by a basal lamina.
LATE LENS VESICLE-
cells of posterior wall
elongate and get filled
with crystallins which
make them
transparent
27. EMBRYONIC NUCLEUS-
the apices of these cells grow
towards anterior lens epithelium.
These are PRIMARY LENS FIBRES.
The nuclei of these cells are
present anteriorly forming nuclear
bow.
When these cells become attached
to the anterior lens epithelium the
nuclei of the cells disappears.
These fibres are formed upto 3
months of gestation.
28. LAYERS OF LENS NUCLEUS
1. EMBRYONIC NUCLEUS- formed by the
primary lens fibres upto 3rd month of
gestation
2. FETAL NUCLEUS- 3rd month to 8th month
3. INFANTILE NUCLEUS- 8TH month till
puberty
4. ADULT NUCLEUS- after puberty
29. Primary lens fibres forms the embryonic
nucleus.
Rest of the nuclei are formed from the
secondary lens fibres. These are the fibres
formed from the anterior epithelium
throughout life .
30. Initially the fibres of
the fetal nucleas reach
both the anterior and
posterior pole.
Later they are not able
to extend all the way
and instead meet at
radiating lines which
appear as an erect Y
anteriorly and inverted
Y posteriorly
31.
32.
33. Later the fibres grow
asymmetrically giving
a complicated dendritic
pattern in the infantile
and adult nucleus
34. The most newly formed (youngest) lens fibres
are present most peripherally outside the
adult nucleus.
These form the cortex of the lens.