Starvation sequence

In this post I'd like to describe the sequence of total stopping of any food intake, providing the water is still available, even if in minimal amounts. To understand the progression, it would be the best to name all the types of nutrients at the beginning, so the further explanation then makes perfect sense.  Three types of nutrients/energy are:

1. carbohydrates (or carbs)

2. fats (or lipids)

3. proteins

Because I couldn't find any flow diagram (anywhere), which would show this sequence of starvation, I was forced to improvise a little. So don't be discouraged by overt simplicity of this flow diagram. Still, (just in case) I want to clarify that symbols between the lines ( | and V ) are supposed to represent the down-pointing arrows. So let's get to it ! 

-----------------------------------------------------------------------------------------------

Fed state, or so-called postabsorptive state, meaning that
all three energy sources are available for usage
 |
V
after 4 hours - carbs are spent from liver and digestive tract, while
fats and proteins levels are still intact
 |
V
12 - 24 hours - carbs spent from whole body, with
slight increase in usage of fats and proteins
 |
V
2 - 4 days - using fats after converting them into ketone bodies (<100 times of normal level), plus
using proteins in the rate of 90g a day
 |
V
4 - 40 days - further using ketone bodies from fat (100-300 times more then in fed state), plus
decreasing usage of protein each day
 |
V
40 days - 2 months - maximum usage of ketone bodies ( >300 times comparing to normal level), with
usage of proteins in the rate of 20g a day
 |
V
2 - 3 months - Body still have some fat, and ketone bodies for energy, but once the body protein level drops to about half of normal level, the physical death will occur through the infection, because the immune system will fail to work efficiently.

---------------------------------------------------------------------------------------------------

Now, let's get through the whole process in slowly in the text format. After your meal, the body will be absorbing all nutrients, which is called the absorptive state. Once all the nutrients are absorbed, the next state is called post-absorptive state, signifying that the absorption is finished, and there is nothing else to digest.

Normally, those two state rotate, as with every other meal you get back into the absorptive state, and so on. But in the case, you stop eating and prolong the post-absorptive state, the first stage is called fasting. This is relatively still healthy state as you force your body to use all available (plus all excess) nutrients that are possibly accumulated in your digestive system.

Fasting changes into starvation roughly around 1-2 days after not eating any food. As I mentioned at the beginning, the water intake needs to be still available, otherwise without water, only 2-3 days will lead to dehydration, decrease of sodium levels, muscular spasm, and physical death. But that's the different story, so let's get back to our starvation sequence.

Roughly 4 hours after the end of the absorptive state and basically the beginning of post-absorptive state, all glucose in the form of glycogen in the liver is gone. That would represent about 25% of glycogen reserve in the body. The resting 75% in the skeletal muscles is then gone within 12-24 hours. This range differs with the amount of activity or rest. But basically after about 2 days of not eating, all the glycogen, and therefore the glucose in the body is gone/used.

To maintain the stable level of glucose in the blood, which is crucial for normal working of nervous system, the body converts fats into the middle-man called ketone bodies. This middle-man looks half the glucose and half amino acid, from which all the proteins are created. Glucose then feed the brain and nervous system, and amino acids are spent for protein synthesis, to save the built-in protein as much as possible.

In this state, the rate of protein usage is about 90g a day, plus with every other day after 2 days, this rate keep decreasing, finally stabilizing at the level of 20g a day in about 40 days. Meanwhile, the level of ketone bodies in the body increase about 100-300 fold. The state called the ketosis is a heavy burden for the organism, especially for the liver and kidneys, which have to take care of it.

Because ketone bodies are slightly toxic substances, they need to be eliminated from the system straight away after they are being used, and therefore, they can't be reused. Because the proteins in the blood, mainly in form of white blood cells incapacitate the toxins in ketone bodies, their level needs to be constantly updated, which is another load for protein usage.

Once the whole body protein level drops to about half, there will not be enough white blood cells for eliminating ketone bodies quickly enough. And at some point, (somewhere between 2 to 3 months), those ketones will overwhelm the immune system, and the result will the that the body will fall prey to the first virus, bacteria, or toxin which will attack the body, and will collapse.

Ironically, even in the time of death, the level of fats will be still at sufficient level to provide more ketone bodies, therefore the energy. But because of the lack of proteins, the immune system will be very frail and inefficient. So technically, the body will never run out of fat, or the energy until the end. It's the infection that will fire that fatal blow, which will result in physical death.

So I hope that this was simple and clear enough to understand the whole sequence. Of course, if at any point the new food intake is provided, the whole process will be postponed, and the cycle will start from beginning. Mainly if all three types of energy are present in fair amount of that particular meal.

Muscle contraction

Muscle contraction is a complex process with one simple objective of enabling the movement to an organism. This complex process can be studied from many different levels, and the knowledge about the musculo-skeletal system reaps benefits in a number of different areas or professions. Generally, the human health during the lifespan is very closely related to normal and effective function of this particular system.

 

D I V I S I O N S

 

Two basic types of muscle contractions are isotonic and isometric. With isotonic, the muscle gets shorter during the contraction, and with isometric, it stays the same lenght. The special type of excercise called isometry is using isometric contractions for developing the strenght of muscles and joints. It's used during the rehabilitations, like for example after having a cast for certain period due the broken bone. The muscle is feeble and significantly smaller so normal exercise is out of question.

 

It's also benefitial for those confined to bed temporarily or long-term. Isometry is basically flexing the muscles without moving or twisting of arms or legs during the contraction. It can be executed by pressing against unmovable object ( for example wall or bed), or simply by pressing two hand against each other. The best thing is that it doesn't require any equipment or skill, and it can be done anywhere and by anyone.  

 

Another special type of involuntary muscle contractions would be cramp or twitching. Stretching and massage are usually very effective in calming down the muscle, as those things usually happen after prolonged exercise or fasting, where the fine balance of electrolytes in the body is disturbed.

 

Muscle contraction works on all-or-none basis as there is no such thing as partial contraction. Plus, it's followed by so-called refractory period, during which the muscle is getting back ready for another contraction.

 

There are three basic types of muscle tissue in the body:

  a) cardiac - muscle of the heart

  b) smooth - muscle in the gut / involuntary

  c) striated - skeletal / voluntary muscles

 

Striated muscles then divides further into two types:

  a) tonic - slow fibres holding mostly the posture

  b) phasic - twitch fibres of two types:

        1 - slow (red fibres)

        2 - fast (white fibres)

 

Another division could be seen depending on the conditions around the muscle contraction. More specifically, it can be done with the presence or the absence of oxygen.

  a) aerobic - with oxygen / using oxygen

  b) anaerobic - without oxygen / creating oxygen dept

 

This oxygen dept is then compensated in the body by flooding the muscle with toxic compound called lactic acid. Accumulation of this substance in the muscle gives that characteristic feeling of burning in the muscle, during and at the end of very vigorous exercise. Lactic acid needs to be quickly eliminated that's why the burning stops soon after you stop moving. Because it's toxic, it's presence is dangerous to the organism, which is dealing with it three possible ways:

 

a) oxidize to pyruvic acid

b) convert to carbs

c) neutralized and excreted

 

Lactic acid and it's effect will make you stop moving, as any further movement at that precise point is litterally painful. It can flood the blood and liver and destroy the living tissue. Regular aerobic exercise and intake of quality food increase the resistance of body towards lactic acid, and more lean muscle tissue the person possess, longer the person can excercise without being stopped by accumulated lactic acid.

 

This diagram shows nicely how muscle contraction actuallly work on the tissue level. Actin and myosin myofilaments work together to create the complex called actomyosin. This complex is then capable of sliding the actin and myosin against each other, and sort of fold them up, shortening the overall lenght of the muscle fibre. Sarcomeres is a fancy term for the muscle cells, and all this model is called sliding filament hypothesis.

 

For muscle contraction to occur, there is a number of conditions that needs to be met, and there is actually a stream of insights coming from knowing those conditions. For the sake of simplicity, I created a simple list:

 

- the presence of the protein called actin

- the presence of the protein called myosin

- the presence of Ca

- the presence of Mg

- the presence of ATP

- the presence of creatine phosphate

- calcium pumps has enough of Ca pumped in

 

Simply put, calcium pumps located on the plasma membrane, pumps in calcium, which triggers all the other processes. Creatine phosphate is another, alternative source of energy in the muscles. They chip in when there is a shortage of ATP, or the exercise is so vigorous, that all energy sources are in the action.
 

3 FORMS OF ENERGY

On molecular level, the muscle has three big sources of energy to reach for. All three are continously available at all times, what differ is the ratios between them, which correlate with the state or activity of body. Plus they differ in how long they can be available, and the time for their recovery. Three form of energy are:

1. fats - triglycerides
2. glucose - monosaccharides
3. creatine phosphate

Fats are the biggest contributor supplying heart and all energy needed for keeping the posture, along with very slow movement. Fat are continuously used by muscles even if you don't move at all. Technically, fats can never run out completelly from the whole body, but their usage by muscles is limited, because it depends on the oxygen input. And that, in turn, depends on the state of your lungs, heart, and basically the whole body. So to burn more fat than you usually do, you need to improve the state of almost whole body.

Glucose is the type of monosaccharide and serves as main energy source for the brain with whole nervous system, which runs only on glucose. Then, muscles use glucose along with its secret source of it - the glycogen. This is sort of animal version of complex carbohydrates and it can be stored in muscles and liver. From there it can be used at any point, and when you then eat carbs again, you refill it.

Interesting thing is the ratio of fats and glucose in which muscles use them. Supposing you are lying down on the bed without moving. Fat / glucose ration would be about 70/30. But the moment you start moving fat goes down and glucose up. The quicker you will move, further the fats will go down, and glucose up in the ratio. Get the picture?

Creatine phosphate is very interesting substance stored in the muscles only. It start working only when we move very fast, or for longer time. It's the additional source of energy that is available for the muscles in the times of shortage of both fats and glucose. There is quite limited amount of creatine phosphate in muscles, so suppose you start running as fast as you can, it can last for about ten seconds. When you stop, and not move for another 30 seconds, it will be replaced with freshly-new made one.

The storage of this substance can be increased by involving the body or muscles in heavy exercise in short bursts. This is the case of sprinters or bodybuilders for example. They train muscles to develop bigger creatine phosphate stores in order to achive greater performance, or appearance. Those three types of energy can be then combined to bring about the movement or sport we need.

 

 This very nice flow diagram describes the muscle contraction cycle in four steps. The diagram is pretty much self-explanatory, so it's all the question of reading and trying to understand. First I recommend to map out the symbols from the key in the grey box, and then reading the steps should make easily a lot of sense on closer observation and study. Good luck and enjoy.
 

Level of glucose in the blood

In this post I'm bringing here one of the most typical representative of the flow diagram. This one explains the process of working on the steady level of glucose ( type of simple sugar) in the blood. This is achieved by so-called negative feedback loop. Negative, because it negates any bigger changes from the balance, and restore the level towards the stable position - within the norm. The mechanism is two-fold.

 

The pancreas creates two hormones called the insulin and the glucagon, and they act in antagonistic way, meaning they function in contrast. Insulin takes glucose from bloodstream into the cells that need it, and this way lower the level of glucose in the blood. Glucagon, on the other hand, supress the action of insulin, so the glucose in the blood starts accumulating again. If I may offer an analogy, they work just like the gas pedal and the break pedal in the car.

 

But this is all pretty basic knowledge. I took this picture out of the GCSE book on Human biology (Letts, 1994)  and technically, we talk the language of sixteen years old pupils. So let's go a bit deeper. The healthy blood glucose level is within the range of  4 to 6 mmol/l. Of course, that level fluctuates during the day as the reflection of having meals containg carbohydrates.
 

After such a meal, the level tends to rise, because the food needs to be digested and all micronutrients (results of digestion) go into the bloodstream. This is the signal for pancreas to release the insulin, which takes the glucose molecules across the cell membrane into the cells. Glucose molecule is too big to cross the plasma (cell) membrane by itself, so it needs the insulin to help widen a gap a little bit.

But then, when you don't eat for a while, the level goes down, and this is a signal for pancreas to release the glucagon, which stops the insulin from doing its job. This way the glucose can't get inside anymore, and stays in the blood. By this mechanism, the relatively stable level is achieved, falling in the healthy range of 4-6 mmol/l. This could be translated as 4-6 milimole per litre of blood, in which one milimole (or thousanth of one mole) is 180 mg of glucose.

I know that this is probably really hard to imagine, so I put it into the perspective. Fluctuation during the day within this healthy range is ok, but hit the level of 10 mmol/l, and you'll be diagnosed with hyperglycemia - which basically means having too much of glucose (sugar) in the blood. Or on the other hand, if your level sinks under 3 mmol/l, then you'll be diagnosed with hypoglycemia - which means not enough glucose in the blood.

So why is so important for the body to have always a stable supply of glucose? Well, many reasons, but probably the biggest one is that the glucose is the only food for the brain, and the whole nervous system. And you probably want those parts to work all the time, and properly. Plus the glucose is used as a fuel for movement. Fat is also a fuel, but glucose is much more readily available for immediate actions and reactions. Lipids chips in mostly when you move very slowly, or not at all (holding the position of the body). But all rapid movements, including your fingers, eyes, or ankles, are down to glucose, so without it (or with low level of it), the body would be pretty slow and stiff. That's why.