Category: SCIENCE

ANATOMY

CLASSIFICATION OF BONES

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BONES
The bones are the hard structure ,Which form the rigid framework the body.
Bone is a highly vascular mineralized connective tissue consisting of cell and dense intercellular organic matrix impregnated with organic salts. The organic material mainly consist of collagen fibers and form one third of the bone.
The inorganic material mainly consist of calcium phosphate and traces of other salts. It provides hardness and rigidity to the bone and makes it radiopaque in x-ray film.
FUNCTION

 Bone give shape and support to the body ,and resist any forms of stress.
 These provide surface for the attachment of muscle ,tendons,ligaments.
 These serve as levers for muscular actions.
 Bone marrow manufactures blood cells.
 Bone store 97%of the body calcium and phosphorus.
 Bone marrow contains reticuloendothelial cells which are phagocytic in nature and take part in immune responses of the body.
 The skull ,vertebral column and thoracic cage protect brain , spinal cord and thoracic and some abdominal viscera ,respectively.
 some bones around the nose contain large cavities filled with air (paranasal air sinuses which affect the timber of the voice).

CLASSIFICATION OF THE BONE

According to shape
According to the structure
According to the development

CLASSIFICATION ACCORDING TO THE SHAPE

Depending on the size and shape. the bone are classified into 7 type.
• Long Bones
• Short Bones
• Flat Bones
• Irregular Bones
• Pneumatic Bones
• Sesamoid Bones
• Accessory Bones

Long bones

Long bone are those in which length exceeds the breadth and thickness.
The long bone are two types.
 Typical long bones
 Miniature/short long bone

Short bones

Short bones are small in size and usually cuboidal in shape , presenting six surfaces. These bones are found in wrist (carpal bone ) and foot (tarsal bone).

Flat bones

Flat bone are flat and shallow plate-like bone.
They form boundaries of certain body cavities. the example of the flat bone frontal, parietal ,occipital ,scapula, ribs, sternum.

Irregular bones

Irregular bone are highly irregular shape ,hip bone vertebrae bone forming base of skull.

Pneumatic bones

Pneumatic bone are a variety of irregular bone which contain air filled cavity. These bones are mainly located around the nasal cavity.
Example maxilla ,frontal ,sphenoid and ethmoid bones.

Sesamoid bones

These are bony nodules found embedded in the tendons or joint capsules.they have no periosteum and ossify after birth. Ex. Patella.

Accessory bones

These bones are not always present. These may occur as ununited epiphysis developed from extra centres of ossification. Ex. Sutural or wormain bones.

CLASSIFICATION ACCORDING TO THE STRUCTURE

Microscopically the architecture of bone may be compact or cancellous.
Compact bone Compact bone is dense in texture like ivory ,but is extremely porous. It is best developed in the cortex of the long bone.
Cancellous bone The cancellous bone is a mesh work of bony spicules.it consist of interconnecting road and plates of bone called trabeculae.

CLASSIFICATION ACCORDING TO THE DEVELOPMENT

According to the process of the bone development. The bones are three type.
Membranous bones are developed by membranous ossification.
Cartilaginous bone are developed by endochondral ossification.
Membrano-cartilaginous bone developed by both membranous and endochondral ossification.

Parts of growing young long bone
 Epiphysis
 Diaphysis
 Metaphysis
 Epiphysis plate

Epiphysis these are ends of long bones which ossify from secondary centers.
Diaphysis It is the elongated part of bone between the metaphysis. It develops from primary ossification center.
Metaphysis the end of diaphysis toward the epiphyseal cartilage is called metaphysis.
Epiphysis plate Epiphysial plate separates epiphysis from metaphysis. Proliferation of the cells in this cartilaginous plate is responsible for lengthwise growth of a long bone.

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ASTRONOMY

SOLAR SYSTEM IN BRIEF

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There are many planetary systems like ours in the universe, with planets orbiting a host star. our planetary system is named the “solar” sytem because our sun is named Sol , after the latin word for sun, “solis”, and anything related to the sun we call “solar.”

Age 4.568 billion years

our solar system formed about 4.5 billion years ago from a dense cloud collapsed, possibly due to the shockwave of a nearby exploding star, called supernova. when this dust cloud collapsed. it formed a solar nebula – a spinning, swirling disk of material. As is typical of molecular clouds, this one consisted mostly of hydrogen, with some helium, and small amounts of heavier elements fused by previous generations of stars.

The solar system consists of the Sun, planets, dwarf planets, moons, and numerous smaller objects such as comets and asteroids. 194 moons, 3,583 comets and 796,289 asteroids have been found in the solar system. 99.86% of the solar system’s mass is found in the Sun.

The Sun is our nearest star. It is, as all stars are, a hot ball of gas made up mostly of Hydrogen. The Sun is so hot that most of the gas is actually plasma, the fourth state of matter. The sun is classified as a G-type main-sequence star, or G dwarf star, or more imprecisely, a yellow dwarf. The planets in order from the Sun based on their distance are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Approx distance between neptune (8th) planet and sun is 4.476 billion km.
It is 143.73 billion km from the Sun, thus giving the Solar System a diameter of 287.46 billion km approx.

Based on where the planets end, you could say it’s Neptune and the Kuiper Belt. If you measure by edge of the Sun’s magnetic fields, the end is the heliosphere. If you judge by the stopping point of Sun’s gravitational influence, the solar system would end at the Oort Cloud. The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars, that is occupied by a great many solid, irregularly shaped bodies, of many sizes but much smaller than planets, called asteroids or minor planets.
The asteroid belt formed from the primordial solar nebula as a group of planetesimals.
Planetesimals are the smaller precursors of the protoplanets. Protoplanets are thought to form out of kilometer-sized planetesimals that gravitationally perturb each other’s orbits and collide, gradually coalescing into the dominant planets.

The Kuiper belt, occasionally called the Edgeworth–Kuiper belt, is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger – 20 times as wide and 20–200 times
as massive. Like the asteroid belt, it consists mainly of small bodies or remnants from when the Solar System formed.
The Kuiper belt is home to three officially recognized dwarf planets: Pluto, Haumea and Make make. Kuiper belt contain comets, mostly ice comets with black colour. When the orbit of the comet brings it close to the Sun, the ice evaporates into space, leaving some of the fine dust sitting on the surface. The dust is fine like talcum powder because comets are too small to have
enough gravity to squeeze the dust together into larger particles. The surface is very black.

The sun sends out a constant flow of charged particles called the solar wind, which ultimately travels past all the planets to some three times the distance to Pluto before being impeded by the interstellar medium. This forms a giant bubble around the sun and its planets, known as the heliosphere.

The heliosphere is the vast, bubble-like region of space which surrounds and is
created by the Sun. In plasma physics terms, this is the cavity formed by the Sun in the
surrounding interstellar medium. The “bubble” of the heliosphere is continuously “inflated”
by plasma originating from the Sun, known as the solar wind.
The heliosphere acts as a shield that protects the planets from interstellar radiation.

The Oort Cloud lies far beyond most distant edges of the Kuiper Belt. While the planets of our solar system orbit in a flat plane, the Oort Cloud is believed to be a giant spherical shell surrounding the Sun, planets and Kuiper Belt. The outer limit of the Oort cloud defines the cosmographic boundary of the Solar System and the extent of the Sun’s Hill sphere. The outer Oort cloud is only loosely bound to the Solar System, and thus is easily affected by the gravitational pull both of passing stars and of the Milky Way itself. The Oort Cloud is made up of icy pieces of space debris.
In short, gravity from the planets shoved many icy planetesimals away from the Sun, and gravity from the galaxy likely caused them to settle in the borderlands of the solar system, where the planets couldn’t perturb them anymore. And they became what we now call the Oort Cloud.
The Oort cloud is thought to occupy a vast space from somewhere between 2,000 and 5,000 au .
The outer limit of the Oort cloud defines the cosmographic boundary of the Solar System and
the extent of the Sun’s Hill sphere.

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BIOLOGY

ENDOCRINOLOGY

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ENDOCRINOLOGY in short and if we get more information then we’ll update this post.

1) ADRENAL GLAND

HORMONE

  1. Adrenaline hormone
  2. Cortisol hormone
  3. Steroid hormone

Adrenaline –

Action of the adrenalin include increasing the heart rate ,increasing blood pressure , expending the air passage of the lunge entering of the pupil in the eye.

CORTISOL –

         Increases the gluconeogenesis in the liver.

Inhibitory effect on insulin which stop transport of glucose into the cells

Cortisol has diurnal variation.

No diurnal change In cushings syndrome.

STEROID HORMONES-

Steroid hormones play an important role in    –

Carbohydrate regulation (glucocorticoids)

Mineral balance (mineralocorticoide)

Reproductive function (gonadal steroids)

Steroid play a important role in inflammatory responses stress responses bone metabolism, cardiovascular fitness, behavior

2) THYMUS GLAND

A pink gland with two lobes located in the thoracic cavity posterior to the sternum.

It is large during the child hood and puberty but shrinks during adulthood.

FUNCTION

         Its primary function is to stimulate the production of T Cells which are an important part of the immune system.

Thymosin also assists in the development of B Cells to plasma cell to produce antibodies.

 Over production of thymosin- Lymphocytosis

3) PANCREAS

HORMONE     Insulin 

FUNCTION-

           Insulin is the only hormone that reduce blood glucose levels and it does this by activating the glucose transport mechanism and glucose utilizing metabolic pathway in different tissues of the body.

    GONADS

4) Testes

Hormone -androgen (testosterone)

Function

  1. Growth development and maintenance of male reproductive organs.
  2. Sexual differentiation and secondary sexual characteristics.
  3. Spermatogenesis
  4. Male pattern of aggressive behavior.
  5. pubertal transformation.
  6. Enlargement of testes ,penis and scrotum.
  7. Pubic and axillary hair.
  8. Bone growth
  9. RBC mass increase
  10. Skeletal muscle mass increase
  11. Larynx enlarges -deeping increase
  12. Development of beard.

5) Ovaries-

Hormone – Estrogens  and progesterone

Function

  1. Maturation growth and development of the reproductive organs
  2. Stimulation of normal physiological process of the tubular reproductive tract.
  3. Growth of the uterine tube
  4. Development of the endometrial lining of the uterus
  5. Increase the vascularity of the uterus
  6. Induction of the behavioral estrus
  7. Dilation of the cervix liquefaction of mucous plug.
  8. Under the influence of the estrogens the uterus is less susceptible to infection.

6) THYROID GLAND

Function of thyroid gland-

  1. Role in growth
  2. It has role in development
  3. It stimulate heart rate and contraction.
  4. Stimulate synthesis of proteins and carbohydrates
  5. It encreases vit. Requirements.

Function of thyroid hormone

  1. Maturation of bone
  2. Maturation of skeletal system
  3. Maturation of nerves in CNS
  4. Regulation of growth hormone
  5. Regulation of body temperature
  6. Generation of heat
  7. Metabolic function
  8. It  influence mood and behaviour

Disorders of thyroid gland – Hypothyroidism

PARATHYROID HORMONE

Hormone  Calcitonin

Function of PTH

             Bone  Parathyroid hormone stimulates the release of calcium from large calcium stores in the bone into the bloodstream.

This increases bone destruction and decreases the formation of new bone.

Kidney Pth reduces loss of calcium in urine.

Pth stimulate the production of active vitamin D in the kidney.

Intestine  pth indirectly increases calcium absorption from food in the intestine via its effects on vitamin D metabolism.

7) PITUITARY GLAND

Posterior pituitary

Hormone     ADH

Function        Stimulate water reabsorption by kidney.

Hormone   Oxytocine

Function   Stimulate uterine muscle contraction release of milk by mammary gland.

Anterior pituitary

Hormone   TSH

Function     Stimulate thyroid gland.

Hormone    ACTH

Function      Stimulate adrenal cortex.

Hormone    PRL

Function      Milk production

Hormone   GH

Function      Cell division , protein synthesis ,and bone growth.

Hormone   MSH

Function Unknown function in humans regulates skin color in lower vertebrates.

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CHEMISTRY/FACTS

CHEMICAL CHANGE

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A change with which you are quite familiar is the rusting of iron. If you leave a piece of iron in the open for some time, it acquires a film of brownish substance.

This substance is called rust and the process is called rusting. Iron gates of parks or farmlands, iron benches kept in lawns and gardens, almost every article of iron, kept in the open gets rusted. At home you must have seen shovels and spades getting rusted when exposed to the atmosphere for some time.

In the kitchen, a wet iron pan (tawa) often gets rusted if left in that state for some time. Rust is not iron. It is different from iron on which it gets deposited.

RUSTING OF IRON:- Let us get back to rusting. This is one change that affects iron articles and slowly destroys them. Since iron is used in making bridges, ships, cars, truck bodies and many other articles, the monetary loss due to rusting is huge.

For rusting, the presence of both oxygen and water (or water vapour) is essential.

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BIOLOGY

Inflorescence

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The reproductive organs of flowering plants are the flowers. Flowers are produced after a period of vegetative growth. The flowers may be borne singly or in clusters.

Flowers when borne singly are said to be solitary (eg) Hibiscus rosa sinensis (shoe flower), if in clusters they form an inflorescence. Inflorescence When several flowers arise in a cluster on a common axis, the structure is referred to as an inflorescence.

The common axis is the inflorescence axis which is also called as rachis or peduncle. Several single flowers are attached to the inflorescence axis. In case of plants possessing underground rhizomes, the rachis or peduncle arises directly from the rhizome. Such a rachis is referred to as scape. In the case of lotus, the scape gives rise to a solitary flower.

In plants like onion, the scape gives rise to an inflorescence. Based on the location, the inflorescence may be classified into 3 types.

(i) Terminal Inflorescence

(ii) Intercalary Inflorescence and

(iii) Axillary Inflorescence.

In plants like Callistemon the inflorescence is found in between the stem. This is called intercalary inflorescence. Generally, based on the arrangement, structure and organisation of flowers on the axis, inflorescences are classified into various types.

There are four major types. i) Racemose

ii) Cymose

iii) Mixed and

iv) Special types

GENERAL KNOWLEDGE/PHYSICS

PRESSURE

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When things push against one another, they produce pressure.

Pressure may be a live of what proportion force pushes against every purpose on associate object’s surface. Here on Earth, we have a tendency to square measure beneath constant pressure. Air might sound like emptiness, however it still has mass, therefore gravity pulls it down toward the bottom. This makes gas pressure, a force unfold everywhere your body.

WHAT IS PRESSURE?
Pressure is what happens once a force pushes on a surface. Additional force makes additional pressure. Once identical force presses over a smaller space, the pressure becomes larger. However if the force is meet a bigger space, the pressure reduces. Sometimes, we do not notice pressure till the force is discharged.

SPREADING THE LOAD
Person will simply stand on a bed of nails. Their body has weight, which implies gravity pulls it down with tons of force. however after they stand on many nails, their weight is shared across all. The pressure on every nail is incredibly little, so that they aren’t getting scraped.

Life would be not possible while not pressure. Blood flows around your body as a result of your heart pumps it with enough pressure to succeed in your fingers and toes. Water will flow to your home as a result of it’s hold on high in reservoirs and tanks. Gravity pulls the water down, giving it pressure that produces it spray from the tap. Pressure is additionally wont to create several tools work, from vacuum cleaners to pushpins, and automotive engines to airplanes.

WHAT IS AIR PRESSURE?
Air on top of pressure is formed by the burden of air you. If you climb a mountain, there’s less air on top of you, and so less gas pressure. It’s more durable for air to induce into your body and more durable for you to breathe. High within the sky, there’s hardly any gas pressure, and respiratory is nearly not possible. Planes have their compartments controlled by pumps therefore individuals within will breathe commonly.

HOW TO LIVE AIR PRESSURE?
Air pressure changes our weather. Air mass brings storms and rain. a
Air mass suggests that sunshine. We are able to predict the weather employing a measuring device to live gas pressure. Within this one may be a box stuffed with air. Because the gas pressure changes, the box squeezes in and out. This moves the needle round the dial.

HEAVY WATER
The deeper you dive to a lower place the ocean, the additional pressure there’s. That is as a result of there’s additional water over your head pushing down. Water is denser than air identical quantity of it weighs more-so water pressure affects things over gas pressure. That is why ventilator diverse will go down solely a brief distance, and why submarines want hulls manufactured from sturdy metal to face up to the pressure. during a milk carton, the liquid close to very cheap is squeezed by the burden of the liquid on high.

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BIOLOGY

PLASTIDS

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Plastids are the largest cytoplasmic organelles bounded by double membrane. These are found in most of the plant cells and in some photosynthetic protists. These are absent in prokaryotes and in animal cells. Plastids are of three types namely chloroplasts, Chromoplasts and leucoplasts. Chromoplasts are coloured plastids other than green. They are found in coloured parts of plants such as petals of the flower, pericarp of the fruits etc.

Leucoplasts are the colourless plastids. These colourless plastids are involved in the storage of carbohydrates, fats and oils and proteins.

The plastids which store carbohydrates are called amyloplasts. The plastids storing fats and oils are called elaioplasts. The plastids storing protein are called proteinoplasts.

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BIOLOGY

RIBOSOMES

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Ribosomes are small subspherical granular organelles, not enclosed by any membrane. They are composed of ribonucleoproteins and they are the site of protein synthesis. They occur in large number. Each ribosome is 150-250A in diameter and consists of two unequal sub units, a larger dome shaped and a smaller ovoid one. The smaller sub unit fits over the larger one like a cap. These two sub units occur separately in the cytoplasm and join to form ribosomes only at the time of protein synthesis.

At the time of protein synthesis many ribosomes line up and join an mRNA chain to synthesise many copies of a particular polypeptide.

Such a string of ribosomes is called polysome. Ribosomes occur in cytoplasmic matrix and in some cell organelles. Accordingly, they are called cytoplasmic ribosomes or organelle ribosomes.

The organelle ribosomes are found in plastids and mitochondria. The cytoplasmic ribosomes may remain free in the cytoplasmic matrix or attached to the surface of the endoplasmic reticulum.

The attached ribosomes generally transfer their proteins to cisternae of endoplasmic reticulum for transport to other parts both inside and outside the cell. Depending upon size or sedimentation coefficient(s), ribosomes are of two types. 70s and 80s. 70s type of ribosomes are found in all prokaryotic cells and 80s type are found in eukaryotic cells. S is Svedberg unit which is a measure of particle size with which the particle sediments in a centrifuge. In eukaryotic cells, synthesis of ribosomes occurs inside the nucleolus.

Ribosomal RNA are synthesized in the nucleolus. The ribosomal proteins are synthesized in the cytoplasm and shift to the nucleolus for the formation of ribosomal sub units by complexing with rRNA. The sub units pass out into the cytoplasm through the nuclear pores. In prokaryotic cells, both ribosomal RNAs and proteins are synthesized in the cytoplasm. Thus the ribosomes act as the protein factories of the cell.

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BIOLOGY

CELL THEORY

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In the year (1839) Schleiden and Schwann have jointly proposed the “Cell Theory” It states that all living organisms are made up of cells and cells are the structural and functional units of all organisms.

Development of Cell Theory

If we study the step by step development of cell theory we will understand how scientific methodology operates. It includes the following steps

1. observation

2. Hypothesis

3. Formulation of theory

4. modification of theory ( if it warrants). Observations were made by Schleiden (1804 -1881) a German botanist.

He examined a large variety of plants and found that all of them were composed of cells. In 1838 he concluded that cells are the ultimate structural units of all plant tissues. Schwann a German Zoologist studied many types of animals and found that animal cells lack a cell wall and they are covered by a membrane. He also stated that animal cells and plant cells were basically identical but for the cell wall.

He observed that both contain nucleus and a clear substance around it. He defined the cell as a membrane bound nucleus containing structure. He proposed a hypothesis that the bodies of animals and plants are composed of cells and their products. Schleiden and Schwann both together discussed Schwann’s hypothesis and they formulated cell theory.

The important aspects of cell theory are:

1. All living organisms are made up of minute units, the cells which are the smallest entities that can be called living.

2. Each cell is made up of protoplasm with a nucleus and bounded by plasma membrane with or without a cell wall.

3. All cells are basically alike in their structure and metabolic activities.

4. Function of an organism is the sum total of activities and interaction of its constituent cells.

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BIOLOGY

SOIL WATER

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Soil water is of paramount importance in the physiology of plants. It occurs in various forms, such as gravitational, capillary, hygroscopic and combined water. Rain is the principal source of water for the soil.

Water which flows down due to the force of gravity is known as gravitational water. The gravitational water is not available to the plants.

However, it is a big soil water reservoir and is trapped out through tube wells. A certain amount of rain water is retained within the intercellular spaces of the soil particles in the form of a capillary network.

It is called capillary water and is used by the plants. Some water molecules form a thin sheet of water around soil particles. It is called hygroscopic water (water of imbibition). The hygroscopic water is also not absorbed by the plants.

The water, which is bound up in chemicals is called combined water or crystalline water. (e.g. MgSo4.7H2O). It is not available to plants. The total water present in the soil is called as field capacity.

Addition of water beyond field capacity causes water logging. It excludes soil air and thus inhibits plant growth. The soils that have poor water holding capacity, cannot afford luxuriant vegetation. In such soils, the plants generally show wilting of their leaves.

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