Physics in Human Body

Physics and biology are two subjects that I enjoy learning- one tasks your mind and makes it solve complex problems while the other teaches you about life and how it functions. Naturally, learning a topic that involves a great deal of both the subjects is immensely interesting, and I had the privilege to do exactly that.

As a part of my examinations I am required to submit a project in each subject I am studying. I had decided that my physics project would be on fluid dynamics, since I was going to learn about this chapter in the coming term. I was surprised to see that fluid dynamics has great application in the human body, specifically the flow of blood in blood vessels. Here are a couple of the fluid dynamic concepts that are found in the flow of blood-

  1. Hagen–Poiseuille equation

The Hagen–Poiseuille equation gives us a relation between the pressure in an artery and it’s radius, length and viscosity of the fluid-

The Hagen–Poiseuille equation, where P= pressure between two ends, L= Length of pipe, R= radius and mu-viscosity.

The fact that pressure is inversely proportional to radius ^4 means that even a small plaque (decreasing the radius of the artery) will have a large effect on the pressure.

2. Bernoulli’s principle

Bernoulli’s principle states that an increase in the velocity of a certain fluid is simultaneous with a decrease in pressure or a decrease in the fluids potential energy.

Bernoulli’s principle can be used to derive the pressure at different parts of the body.

As per Bernoulli’s equation

P+1/2ρv2+ρgh=constant. The kinetic energy term can be ignored as the velocities in the three arteries are small (≈ 0.1 m/s) and almost constant. Hence , the blood pressure at the brain Pb, the heart Ph and the foot Pf are related by

Pf = Ph +ρghh= Pb +ρghb

Typical values of height to the heart and the brain are hh=1.3 m and hb=1.7 m.

Taking ρ=1.06 x103 kg m-3 , Ph =13.3 kPa

Pf =26.8 kPa and Pb =9.3 kPa

Since 1mm of Hg= 0.133kPa

Pf =200 mm Hg, Pb = 70 mm Hg

Thus, the pressures in the lower and upper parts of the body are quite different when a person is standing but are almost equal when the person is lying down. In terms of mm of Hg, value of Ph is 100 mm of Hg.  

The above two concepts are both very important when it comes to determining the rate of flow to blood in an artery, blood’s viscosity, diameter of an artery, medications of blood pressure, etc.

I had great fun doing this project and certainly hope that I will get many projects like these which have a great extent of cross curricular links!

Action in the Biology lab

It’s back to school and we’ve started with some rather interesting experiments in the bio lab

This term’s syllabus includes plant tissues, and as a part of the chapter we are creating sections of monocot and dicot stems for examination under the microscope.

This is a monocot stem cross section that I made in the lab-

Monocot stem

The scattered vascular bundles and absence of pith are clearly visible in the picture.

This is the dicot stem cross section I made today-

The meta and proto xylem are visible, along with the prominent pith and cambium.

I also performed an experiment at home – viewing stomata under the microscope. Here is a picture of the slide-

The stomata are circled

the small stomatal pore can be seen between the two guard cells.

My visit to the Natural History Museum, Vienna

Boasting 8500 square meters filled with ancient biological objects, the Natural History Museum Vienna is one of the largest and most important natural history museums in the world. My visit to this museum was a truly amazing one – I was able to see thousands of prehistoric objects such as fossils, primitive human skeletons, objects made during the stone age era, dinosaur skeletons, meteorites and much, much more.

Learning about evolution was the highlight of my trip – I was able to see skeletons of many pre-human species and learnt quite a lot. I was also able to crosslink what I read in the museum with my previous knowledge that I had accumulated while studying evolution in school.

Complete skeletons of species like Australopithecus afarensis and Homo ergaster were on display. I was able to identify stark characteristics of the Australopithecus such as its parabola jaw, protruding eye ridges and receding forehead. Quite a lot of information about hominoid offspring, the development of language, discovery of fire and famous prehistoric humans (such as Lucy) was available.

Homo Erectus/Ergaster skeleton
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An Australopithecus skeleton

Microbiology was another large section of the museum. Detailed diagrams of protists and Monerans were on display. I was able to see simulations of conjugation, transformation and transduction reproduction processes.

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A well labelled model of a plant and animal cell

However, this was a very small part of the huge museum. thousands of fossils were to be seen- one really interesting fossil was that of a fish, that had choked on a smaller fish it was trying to eat. It had been fossilised with half a fish sticking out of its mouth. Huge fossils of Ammonits that inhabited the Earth 250 million years ago were to be seen.

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One can see the oversized prey that choked its predator to death. It seems this fish bit off more than it could chew

Like in any other natural history museum, Dinosaurs were another major attraction. the museum had large complete skeletons of dinosaurs, among which was an infant dinosaur emerging out of its egg.

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Dinosaur eggs

Large exhibitions of animals and insects were on display. I was able to closely examine the anatomy of marine animals, reptiles and insects. while it was very informative, seeing dissected snakes did send shivers down my spine. There were a large number of stuffed animals on display, along with information about their anatomy.

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A dissected fish – its anatomy was similar since I done a few dissections myself

One rather amazing fact that I learnt was that fishes in polar oceans have antifreeze in their blood! A common Antarctic species, the Antarctic cod (family Nototheniidae) has an effective frost protection – ‘antifreeze glycoprotein’ (AFGP). Another fish, the Antarctic silverfish (Pleuragramma antarcticum) has an AFGP that lowers the freezing temperature by 3.4′ C when present in the blood at a concentration of 50 mg/ml.

Apart from biological specimens, I was able to see a large number of natural rocks – thousands of precious, semi-precious and common rocks were displayed. One of the main attractions were seeing gold and diamonds in their mined form – while seeing diamonds in jewellery was commonplace, seeing a diamond embedded in rocks was truly amazing.

But naturally, all these rocks were overshadowed by the largest collection of meteorites in the world. Their smooth, pure metal like texture amazed me. A rather brilliant simulation of the impact of different sized meteorites on the earth was also very interesting to watch.

A meteorite

All in all, I really enjoyed my experience at the Natural History Museum in Vienna. I learnt quite a lot of information, which was not only interesting but also useful academically. I would certainly recommend a visit to this treasure trove containing millions of artefacts on display.

A scissor for genes

Diseases like Cystic Fibrosis and Muscular dystrophy have devastating effects on the human body. Any individual who has these genetic defects leads a life of misery and pain. While previously thought to be untreatable, a new breakthrough in genetic science known as CRISPR has finally created becons of hope for patients with genetic disease.

I had taken up CRISPR as my topic for a science exhibition that was being hosted by my school. Here is a picture of my project

CRISPR is a gene editing tool, which can be used by scientists to edit genes inside cells. An enzyme called Cas9 is used to cut DNA. Guide RNA is used to guide the enzyme to the target DNA. The guide RNA contains a sequence that matches the sequence of the target DNA. Cas9 and guide RNA join together. Cas9 unzips the DNA, the RNA matches up with the unzipped DNA strand and finally Cas9 uses molecular scissors to cut the target DNA.

MY OPINION

While CRISPR Cas9 is a revolutionary tool in the field of genetic modification, it has its own share of technological and ethical drawbacks. While better than its previous competitors, the tool can have minor mistakes. In genetics, even minor mistakes can spell utter disaster.

When one looks into the ethical side of the spectrum, there seems to be nothing wrong with the current model of the project – a tool to cure people of fatal genetic problems. But what if CRISPR evolves into something different? What if the tool evolves into one being used for genetically engineering babies? Would it be fair to allow super rich individuals to create the perfect human, while the poor cannot? This reminds me of Theodore levitt’s quote ‘anything in excess is poison’. Currently, patent rights of the tool are being fiercely contested by its creators, and it could be a boon for mankind, as well a poison for the future.

While I was presenting my project in the school, it got noticed by my principal. I received an encouraging feedback. She also tweeted about my project on her twitter page. Below is the link to the tweet.

https://mobile.twitter.com/KNargish/status/853159510948663296

MY FIRST MICROSCOPE EXPERIMENT

Our world is teeming with tiny microorganisms that are invisible to us unless viewed under a microscope. My interest in biology was not confined to what we could just see – it spread, of course, to what I couldn’t see through naked eye. This yearning to be able to see microbes under the microscope at any time I wanted drove me to buy a microscope. I got my microscope when I was in eighth grade.

I decided to first perform the onion peel experiment. I chose it for its simplicity in preparing the slide. Here is the procedure I followed-

  1. Cut an onion into medium sized pieces and place them in a watch glass filled with water.
  2. Remove a translucent and thin epidermis from the upper layer of an onion piece. Carefully place this epidermis on the slide using forceps.
  3. Using a dropper, put about 2-3 drops of safranin dye on the epidermis. Allow this setup to rest for about 5 minutes.
  4. Carefully place a cover slip on the epidermis. Remove excess solution using blotting paper.

Here are my observations after viewing the slide under a microscope-

  1. There are a large number of regularly shaped cells lying side by side, much like the arrangement of bricks. Cells obtain their shape due to the rigidity of the cell wall.
  2. A distinct nucleus is present on the periphery (edges) of each cell ( an alternate experiment can be performed to view the nucleus using acetocarmine solution).
  3. Each cell has, within its cell wall, lightly stained cytoplasm.

Here is a picture of my experiment –

Hello

I’ve always had an interest in biology and medicine – the study of life is filled with intriguing facts about organisms that inhabit our home (earth). Nothing gives me more pleasure than sitting down with my microscope and viewing specimens of insects, plants and their cells.

In this blog, I shall be writing about my own experiences involving biology – what interesting things I learnt in bio class, experiments that I did, dissections, specimen collections and microscope slide making. Along with biology, I shall also be writing about developments in medicine and technological advancements in the field. This will include discoveries of new methods to treat diseases, new machines used in the treatment of diseases, discovery of new diseases, etc.

I do hope that you will enjoy reading about the aforementioned topics. Do follow my blog to get regular updates about my posts.

Thank you

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