Monday, July 30, 2012

The Heart Still Goes On... While Muscles Tire

You are off on a long walk... a hike in the woods... it seems like you have been walking for hours... your legs are aching and dragging... but surprisingly, your heart is racing on and beating faster than ever. Hmm... Strange, isn't it?

The heart is also made of muscles. The heart has been beating since you were born, and will keep on beating till the end. It beats roughly once per second normally and can beat up to an astonishing 3 times a second when you are stressed! When other muscles of your body tire out regularly and complain on overuse, why doesn't the heart ever do so?

Let"s first understand how muscles work. Muscles convert energy into motion (or force) - they use energy from the food that we eat and help move various body parts. The only movement a muscle is capable of is contraction. Because of the ways in which the muscles are attached to our bones and body parts, they make the levers, pulleys and other mechanical contraptions that use this basic contraction motion to achieve the amazingly complex activities that we can do. The mind boggles thinking of this.

Muscles are fibres made of muscle cells - the building blocks of our body. Each cell is capable of converting energy into motion through a complex chain of chemical reactions. The energy they use is in the form of a chemical called ATP (Adenosine Tri Phosphate). When ATP is broken down with a chemical reaction with water to simpler forms, it releases energy. That is what the cells use to do work.

Mitochondria in our cells

ATP is produced inside the cells in a unit called the mitochondrion. The more mitochondria a cell has, the more energy it can produce and the more work it can do.

ATP can be produced in two ways:

Aerobic: The food that we eat is converted into a simpler form called glucose in the stomach. Glucose gets absorbed into blood and transported to all cells of our body. ATP is produced using glucose and oxygen right inside the cells where it is consumed. Carbon dioxide is produced as a byproduct which gets transported out by the blood and we breathe it out from our lungs.

An-aerobic: ATP can also be produced without oxygen. This process of not using oxygen is less efficient. It makes less number of ATP that the aerobic process. It also produces toxic  byproducts other than carbon dioxide that can not be removed as fast. They tend to accumulate in the muscles, reduce their efficiency and cause muscle pain and fatigue.

Energy production in a mitochondrion

Now that we have some interesting facts, let us piece together the answer to our puzzle...

There are two primary reasons why our muscles tire out much before our heart:

Reason 1:
The heart muscles have plenty of oxygen available, they being right where our lungs are. We breathe through our lungs, remember? So the heart gets the freshly absorbed oxygen before any other organ gets it!

Reason 2:
The heart muscles are built specifically to use aerobic energy. They are rich with mitochondria and of the kind that can use oxygen and glucose to produce energy. Since they almost never produce energy without energy, they do not accumulate toxic wastes and do not get fatigued easily! Till it has enough oxygen and glucose available, that is.

Then why are not all muscles like heart muscles? Then we would never get tired!

Well, our body is optimized for the conditions it encounters most. In most cases, under mild strain, our body has enough oxygen to cleanly burn food for energy. It is only during occasional high demands, when it has to dip into its reserves for extra energy - and burn what ever it can however to meet the demand.

Moreover they type of reaction used to create energy determines the speed at which the muscle can operate. Aerobic reactions are cleaner, but they are also slower. They are also limited by the amount of oxygen we can breathe. When our muscles need to operate fast, they must get part of their energy in the anaerobic way to work faster. Most of our skeletal muscles need to have and do have both kinds of muscles - those that can work best with oxygen and those that can without.

Multimedia credits:

Thursday, June 21, 2012

Early Smartphone - Under the Hood

Almost all mobile phones that we see today are 'smart'. :) Well, if a phone can play music, movies and games, can store unlimited contacts, let us browse the internet, write notes and documents, and let us install apps to do whatever else we want to do, ought to be smart. Don't you agree?

Mobile phones in early days were not all that 'smart', or shall we say multi-functional, though they were no doubt good at whatever they were intended to do. One of the earliest smart phones just combined a phone and a PDA (personal digital assistant) into the same device. One of the earliest PDAs were running the Palm OS (like some of us run Windows on our PCs today). The Palm OS could recognize gestures written using a stylus, it was touch enabled, had a web browser to browse the internet, and allowed applications and games to be installed by users.

Since when I was a child, I always took apart things to see what was inside. I had one such palm based smart phone long time ago, which went bad and could not be repaired. In this article, I'll take it apart to show you what it looked like under the hood - just for curiosity's sake.

1. This is how the phone looked. It was a bulky flip phone. The top portion had a touch sensitive screen. The bottom portion had the keypad and a small touch sensitive area for scribbling with the stylus.

2. The back cover removed. You can see the stylus tucked in on one side and the antenna on the other side. At the top you can see a small motor with a small semicircular weight at its tip. This is used to vibrate the phone when in vibrator mode. When the motor rotates, the non uniform rotational force caused by the semicircular weight vibrates the phone.

3. This is the back side of the circuit board after removing the back cover. We can see the connectors used for the battery, the antenna and the vibrator.

4. The top circuit board removed. This is the front side where we can see the components attached to the board. The large square chip with 'Qualcomm' written on it signifies that this is the board for the mobile phone circuit (Qualcomm makes mobile phone chips). The long white strip has a series of connectors that are used to make contact with the next circuit board.

5. The two circuit boards are separated with an aluminum layer that also probably acts as a shield for electrical fields. Since the mobile phone circuit deals with pretty strong electro-magnetic fields, it was probably necessary to isolate the other circuits from it. Do you notice the thick copper lines in the circuit above? The ridges on the aluminium separator match the copper lines exactly. That's the ground connector.

6. This is the 2nd circuit board for the Palm based PDA. Here the large square chip with 'Dragonball' written on it is the CPU of the PDA. The metallic clip like device held memory card (SD card). The battery charging and external connector terminals are connected to this circuit. It also is connected to another small LCD display that displays short information strings like the caller Id, battery charging indicator and such stuff which can be seen without opening the flap.

7. This is the keypad. Each key is a small switch with the concentric circles forming the terminals. The keypad has a conducting plate at the bottom of each key that connect the terminals when pressed.

After taking the pictures, I carefully put the circuit back as it was. Weren't the components on the circuit board tiny? Newer phones have even more compact circuits. Today more and more of the circuits are being crammed into tiny integrated circuits (ICs - the black squarish components that you saw). They make electronic items smaller, cheaper to manufacture, and consume less power than larger components.

Sadly though, as components become cheaper and better with time, people find it easier to just throw old equipments and buy new ones in their place. So like plastics, we are slowly filling our junkyards with lots of electronic waste. The right thing to do would be to use gadgets for as long as possible, and when we replace a working gadget, we should pass the old one to someone who can make use of it. If it is not working, we should give it to someone who can recycle it appropriately.

In my case, though the phone didn't work, the palm PDA was working. I will be cleaning and restoring it before giving it off to be used by some kid who cannot afford a PDA. In future articles, I will be opening and showing you what lies under the hood of a few other items that I had.

Sunday, June 10, 2012

Why don't we eat flowers?

Think of some plant products that we eat. Chances are it is either a fruit, seed, leaf or roots of a plant. Rarely do we eat flowers. Why so?

Fruits and seeds are storehouses of energy. Fruits are intended to be eaten by others, so that the seeds get dispersed far and wide. Seeds are intended to store food for the sprout that grows from them.

The roots that we eat (potato, beet, carrot) are actually specialized roots that store energy too. That's why they are rather unusually shaped and much larger than roots of other plants.

Leaves are the kitchen of the plant. Leaves do not have too much energy in them, but they have many essential minerals and vitamins that we need to repair our body and carry out subtle chemical wizardry in our brains and glands. Leaves also have fibres that help keep our digestive system in good shape. And hey, leaves are available in plenty!

Flowers are however small in size. They are not available all the time of the year. Moreover, flowers don't last long, usually a day or two. That makes it difficult for us to gather enough quantity of flowers to make a meal.

Think about what purpose a flower serves to a plant. It is mostly to attract insects for pollination. The flower is therefore specialized for that purpose, having scents, colors, fluorescence and what not to get those bees to notice them. They are laden with chemicals. There's no energy - like carbohydrates, no proteins either which help us build our body, and usually not much minerals/vitamins. So if we eat flowers, we don't really get anything much of use. Rather, we are in the danger of having an overdose of strange chemicals that the flower may have, which can make us sick.

 It is like this not only for humans, but for most animals. It is how plants have evolved to ensure that the flowers don't get eaten away before they had a chance to bear fruits and seeds. Very clever, isn't it? Well, nature had all the time to learn from itself and set things to perfection!

We have leant not to have flowers as their main diet. Flowers are like spices. They taste and smell good in small quantities. But we can't tolerate too much of them.

There are some flowers we eat as accompaniments and flavoring agents. Rose petals, and marigold petals are used with milk and sometimes pickled. Jasmine is used to flavor tea. Saffron is used to flavor and color delicacies.

There are also some flowers that are eaten in slightly larger quantities. Cauliflower is a common example. Cauliflower is really not a flower, it is just the part of the plant that holds the flowers. The real cauliflower flower is too small to be eaten. Banana flowers are are also eaten, but it requires lot of preparation to remove the caustic flower parts. Neem flowers are also eaten in some places, but in small quantities because of their bitter taste.

Do you know of any flowers that you eat? Tell us!

Multimedia credits:
Science photo library
Britannica Encyclopedia

Saturday, May 19, 2012

Why did we evolve to cry tears?

We all cry some time or other. Sometimes when we are hurt physically, and sometimes when we are hurt emotionally. As young children we make crying noises along with tears. As we grow up, we learn to weep silently. And sometimes our eyes get tears without us making any noises.

If you believe in the theory of evolution, everything we are today must have a reason, right? Unless there was some evolutionary advantage in shedding tears, we wouldn't have evolved to cry. So what is it?

Let's trace a possible evolutionary path we might have taken.

Let's think of a newborn baby. A human baby needs to be tended to by its parents, but the baby must be able to communicate a few simple messages to help them. To start with, it needs to indicate when it is uncomfortable (for any reason like hunger, cold, hot, pain) and when it is content. It will take the baby quite some time to learn to speak, but what the hell, it can yell out in the meantime! So that's what babies do, squint their faces and let air out from their lungs to make the crying sound. The louder they cry the harder they squint.

A hard squint squeezes the tear gland and releases tear drops into the eye. So while just a crying sound indicated some discomfort, tears definitely indicated great discomfort. A baby who cried tears got more attention than a baby who just made noises. So they got fed more, got stronger and had more children than others who did not shed tears. Slowly, the brain evolved to link the emotion of discomfort to the tear gland. Such a linkage allowed the brain to 'cheat' and shed tears more easily.

Once emotion got linked to it, it became sort of involuntary for us. It was partly under the brain's control. Like the wag of a dog's tail.

A grown up child who can speak doesn't need to cry to indicate discomfort. It can do much better by telling what exactly is bothering him/her. So grown up children do not cry if they can communicate their discomfort. It is easier and faster to fix the problem that way.

But sometimes it is not possible or difficult to communicate. Either because the other party is refusing to understand, or it is something that is difficult for the child to explain effectively. That is when the brain brings out those tears, sometimes also accompanied by cries. They are intended for the people watching him/her, they would then know that the pain that the child is experiencing is more that what their physical actions show. In the history of evolution, children who could do this definitely got a better deal that others who could not. So we evolved to retain our crying till young adulthood.

When the child grows up even more to become an adult, it becomes emotionally more complex. Emotional hurt sometimes gives him/her as much or more pain than any physical hurt. Sometimes he/she may get emotionally overwhelmed by just thinking of something. Then, involuntarily, the brain kicks in the tears to display the emotions. If there was someone watching, they would sympathise with the person and do something to calm them or resolve the problem. Such people who could cry even as adults would get better emotional help from others than people who did not cry. They would be emotionally better off, and hence we evolved to retain our crying habits till adulthood.

Slowly it became such an important part of our complex emotional framework that sometimes just crying out without anyone seeing us also calmed us down. It served as an emotional vent to let off some grief.

And of course, being humans with high IQ, we quickly learn to cheat, even ourselves. Sometimes with a bit of effort, some of us can bring out false tears. That is like lying to get certain advantages, but we have learnt to do it as well.

And by the way, if after reading this you are thinking that people who cry easily get everything easy, you are wrong. Unnecessary and frequent crying puts off people around and can have negative results!

Wow! Such uses of some silly small drops of salt water!

Some things to ponder on:
- why do we laugh?
- why do tears come out when we are too happy?
- do animals shed tears?

Tuesday, February 14, 2012

Why are Cereals Carbs while Legumes are Protein

Seeds we eat
Cereals (like rice, wheat and corn) and legumes (like lentils, dal and beans) are an important part of our daily diet. Moms always give a healthy mix of cereals and legumes in our diet. Cereals are for the carbohydrates - stuff that give us the energy. Legumes are for the protein - stuff that help us build our body (muscles and tissues).

Both cereals and legumes are seeds of plants. Have you ever wondered why legume seeds are rich in protein while cereals are just carbohydrates? Vegetable oil is made from only certain type of seeds (like mustard, soyabean, sunflower). Why don't we make oil from wheat or rice?

First of all, let us all recollect what a seed is. A seed is from where a new plant is born. The birth of a plant and its growing out of the seed is called germination. Unlike us, who eat other stuff to live, plants have to make their own food from soil water and sunlight. Till the baby plant grows a couple of leaves and a bit of root, it can't even make its own food. Like we had our moms to feed us when we were babies, the seed must contain enough food to help the baby plant grow in the initial stages.

Germinating Seed
The seed is therefore a storehouse of energy and nutrients, everything packed together in a nice little packet. Energy can be packed most efficiently as carbohydrates and fats. Proteins don't have much energy, but they have stuff called amino acids that are the building block of living tissue. Seeds need to contain bits of all three types of nutrients. But the exact quantities of each differs.

And in fact, even rice and wheat do have protein and oil. But they don't have as much of it as some legumes. Legumes have around one third of their calories as protein/oil. Rice has only one twentieth. And that too mostly in the seed cover that we throw away.

So why do legumes have higher protein? Well, legume plants have one unique characteristic. A certain kind of bacteria lives in the roots of legume plants, that with the help of the legume plant, can absorb large amounts of nitrogen from the atmosphere and store it in the soil. The bacteria form small protrusions or nodules in the roots of the legumes where they live. They don't harm the plant in any way and the plant doesn't harm them either. The plant protects the bacteria from its enemies and in return the bacteria absorb the nitrogen for the plant.

Nitrogen fixing bacteria nodules

Because of the bacteria, the legume plant has abundant nitrogen available to it. Nitrogen is an essential constituent of proteins. So that's the reason! Legumes are seeds, storehouses of energy just like any other seed like wheat and rice. They just happen to have access to abundant nitrogen, which they store as proteins in the seeds. Volia!

Some things to ponder on:
- What are fruits? They are definitely not seeds, but they have the seeds. Why are they required?
- Why do some seeds have more oil than others?
- If protein is what living tissue is made of,

Wednesday, January 11, 2012

Around the World

Theres a playground near my house. It is circular and about the size of a football or cricket field. I usually cycle on the track that runs around the edge of the ground. I once did a rough measurement and its radius was around 63 metres. Doing such a rough measurement is simple. I just started from the center and counted how many times I had to pedal do reach the edge. I do around 1.5 meters on a full turn of my pedal... so it is easy to get a good enough measure of the radius.

The Earth is around 100000 times larger than this playground. Earth's radius is around 6300 km (1 km = 1000 metres). That means if someone cycled on a track around the equator, they would be covering 100000 times what I do in the playground! It is impossible for any one to do it though. May be we could do it if we were birds.

There is a road that runs outside this playground. I sometimes cycle on that as well. The road runs all round outside the playground, around 7 meters away from it. I figured that because the radius of this road is 7 metres more than that of the playground, I was cycling 44 metres more for every full circle on the road than in the playground. We all know it... larger circle and hence larger circumference.

Now here's the question... We know that:

  • If I cycle 7m away from the playground track, I cycle 44m more than what I would by cycling on the track.
  • The equator in 100000 times larger than my playground.

So if a bird flies 7m above ground around the equator, how much more distance it will cover than what it would if it hopped along on the ground?

I'm sure you can answer it and you may find it amusing. I'll put up the answer in a few days. In the meantime, if you know the answer, do put it up as a comment!

Ok... So let us try to understand the matter.
The circumference of a circle varies with its radius (roughly 6 times) by the formula:
circumference = 2 * pi * radius, where pi is the magic number 22 / 7

With this information, lets see how myself and the bird fare when we both increase our path radius by 7m.

Me on the playground:
Radius of playground = 63 m
Circumference = 2 * (22 / 7) * 63 = 2 * 22 * 9 = 396 m
Radius of road 7m away = (63 + 7) m
Circumference of road = 2 * (22 / 7) * (63 + 7) = 396 + (2 * 22) = 396 + 44 m
Difference in circumference = 44 m

Bird flying around the earth:
Radius of earth = 6300000 m
Circumference = 2 * (22 / 7) * 6300000 = 2 * 22 * 900000 = 39600000 m
So a bird hopping along on the ground will cover 39600000 m.
Radius that is 7m above the ground = (6300000 + 7) m
Circumference of circle 7m above ground = 2 * (22 / 7) * (6300000 + 7) = 39600000 + 44 m
So a bird flying 7m above ground will cover (39600000 + 44) m.
Difference in circumference = 44 m

So, it does not matter whether it is me cycling around a track or a bird flying around the world. The length of our paths may be very different, but if we increase the radius of our paths by 7m we cover the same 44m additional distance.