What does pancreas do?

Beneath your ribs, you'll find, among other things, the pancreas, an organ that works a lot like a personal health coach.
This organ controls your sugar levels and produces a special juice that releases the nutrients from your food to help keep you in the best possible shape.

The pancreas sits just behind your stomach, an appropriate home, as one of its jobs is to break down the food you eat.
It aids digestion by producing a special tonic made of water, sodium bicarbonate, and digestive enzymes.

Sodium bicarbonate neutralizes the stomach's natural acidity, so these digestive enzymes can perform their jobs.

Lipase breaks down fatty substances, protease splits up proteins, and amylase divides carbohydrates to create energy-rich sugars.
Most of those nutrients then get absorbed into the blood stream, and go on to enrich the body.

While all this is happening, the pancreas works on another critical task, controlling the amount of your blood.
It achieves this with the hormones insulin and glucagon, which are produced in special cells called the Islets of Langerhans.
Having too much or too little sugar can be life threatening, so the pancreas must stay on constant alert.

After a big meal, the blood often becomes flushed with sugar.
To bring us back to normal, the pancreas releases insulin, which makes the excess sugar move into cells, where it's either used as an energy source, or stored for later.

Insulin also tells the liver to shut down sugar production.
On the other hand, it blood sugar is low, the pancreas releases a hormone called glucagon that tells the body's cells and liver to release stored sugars back into the bloodstream.

The interplay between insulin and glucagon is what keeps our sugar levels balanced.
But a faulty pancreas can no longer coach us like this, meaning that this healthy balance is destroyed.
 If It's weaken ed by disease,the organ's ability to produce insulin may be reduced,or even extinguished,which can trigger the condition known as diabetes.
Without regular insulin release, sugar steadily builds up in the blood, eventually hardening the blood vessels and causing heart attacks, kidney failure, and strokes.
The same lack of insulin deprives cells of the energy-rich sugar, they need to grow and function.
People with diabetes also tend to have higher levels of glucagon, which makes even more sugar circulate.
Without this internal health coach, our sugar levels would go haywire, and we wouldn't be able to digest important nutrients.

But like any coach, it's not the pancreas'job alone to keep us healthy.
It needs our conscious participation, too.

How blood pressure works?

If you lined up all the blood vessels in your body, they'd be 95,000 kilometers long and everyday, they carry the equivalent of over 7,500 liters of blood, though that's actually the same four of five liters recycled over and over,delivering oxygen, and precious nutrients like glucose and amino acids to the body's tissues.
All that blood exerts a force on the muscular walls of the blood vessels.
That force is called blood pressure, and it rises and falls with the phases of the heartbeat.
It's highest during systole, when the heart contracts to force blood through the arteries.
This is your systolic blood pressure.
When the heart is at rest between beats, blood pressure falls to its lowest value, the diastolic pressure.
A typical healthy individual produces a systolic pressure between 90 and 120 millimeters of mercury, and diastolic pressure between 60 and 80.
Taken together, a normal reading is a bit less than 120 over 80.
The blood traverses the landscape of the body through the pipes of the circulatory system.
In any plumbing system, several things can increase the force on the walls of the pipes: the properties of the fluid,extra fluid, or narrower pipes.
So if the blood thickens, a higher pressure is needed to push it, so the heart will pump harder.
A high-salt diet will lead to a similar result.
The salt promotes water retention, and the extra fluid increases the blood volume and blood pressure, and stress,like the fight or flight response, releases hormones, like epinephrine and norepinephrine that constrict key vessels, increasing the resistance to flow and raising the pressure upstream.
Blood vessels can usually handle these fluctuations easily.
Elastic fibers embedded in their walls make them resilient, but if your blood pressure regularly rises above about 140 over 90, what we can hypertension, and stays there, it can cause serious problems.
That's because the extra strain on the arterial wall can produce small tears.
When the injured tissue swells up,substances that respond to the inflammation, like white blood cells, collect around the tears.
Fat and cholesterol floating in the blood latch on, too, eventually building up to form a plaque that stiffens and thickens the inner arterial wall.
This condition is called atherosclerosis, and it can have dangerous consequences.
If the plaque ruptures , a blood clot forms on top of the tear,clogging the already narrowed pipe.
In the clot is big enough, it can completely block the flow of oxygen and nutrients to cells downstream.
In vessels that feed the heart, that will cause a heart attack, when oxygen-deprived cardiac muscle cells start to die.
If the clot cuts off blood flow to the brain, it causes a stroke.
Dangerously clogged blood vessels can be widened by a procedure called an angioplasty.
There, doctors thread a wire through the vessel to the obstructed site, and then place a deflated balloon catheter over the wire.
When the balloon is inflated, it forces the passageway open again.
Sometimes a rigid tube called a stent is placed in a vessel to held hold it open, letting the blood flow freely to replenish the oxygen-starved cells downstream.
Staying flexible under pressure is a tough job for arteries.
The fluid they pump is composed of substances that can get sticky and clog them, and your typical healthy heart beats about 70 times a minute, and at least 2.5 billion times during an average lifetime.
That may sound like an insurmountable amount of pressure, but don't  worry, your arteries are well suited for the challenge.

How vitamins work?

A, C, E, D, B, K,
No, this isn't some random, out of order alphabet.
These are vitamins, and just like letters build words.
there are the building blocks that keep the body running.
Vitamins are organic compounds we need to invest in small amounts to keep functioning.
They're the body's builders, defenders and maintenance workers, helping it to build muscle and bone, make use of nutrients, capture and use energy and heal wounds.
If you need convincing about vitamin value, just consider the plight of olden  day  sailors, who had no access to vitamin-rich fresh produce.
But vitamin C,abundant in fruits and vegetables,While bacteria,fungi and plants produce their own vitamins,our bodies can't, so we have to get them from other sources.
So how does the body get vitamins from out there into here?
That's dependent on the form these compounds take. Vitamins come in two types:lipid-soluble and water-soluble,and the difference between them determines how the body transports and stores vitamins,and gets rid of the excess.
The water-solubles are vitamin C and B Complex vitamins that are made up of eight different types that each do something unique.
These are dissolved in the westerly parts of fruits, vegetables and grains, meaning their passage through the body is relatively straightforward.
Once inside the system, these foods are digested and the vitamins within them are taken up directly by the bloodstream.
Because blood plasma is water-based, water-soluble vitamins C and B have their transport cut out for them and can move around freely within the body.
For lipid-soluble vitamins,dissolved in fat and found in foods like diary,butter and oils,this trip into the blood is a little more adventurous.
These vitamins make it though the stomach and the intestine,where an acidic substance called bile flows in from the liver,breaking up the fat and preparing it for absorption through the intestinal wall.
Because fat-soluble vitamins can't make use of the blood's watery nature, they need something else to move them around,and that comes from proteins that attach to the vitamins and act like couriers, transporting fat-solubles into the blood and around the body.
So, this difference between water-or fat soluble vitamins determines how they get into the blood, but also how they're stored or rejected from the body.
The system's ability to circulate water-soluble vitamins in the bloodstream so easily means that most of them can be passed out equally easily via the kidneys.
Because of that, need to be replenished on a daily basis through the food we eat.
But fat-soluble vitamins have staying power because they can be packed into the liver and in fat cells.
The baby treats these parks like a pantry,storing the vitamins these and rationing them out when needed,meaning we shouldn't overload on this type of vitamin because the Brady is generally well stocked.
Once we figured the logistics of transport and storage, the vitamins are left to do the work they came here to do in the first place.
Some, like many of the B Complex vitamins, make up coenzymes, whose job it is to help enzymes release the energy from food.
Other B vitamins then help the body to use  that energy.
From vitamin C, you get the ability to fight infection and make collagen, a kind of tissue that forms bones and teeth and heals wounds.
Vitamin A helps make while blood cells,key in the body's defense,helps shape bones and improves vision by keeping the cells of the eye in check
Vitamin D gathers calcium and phosphorus so we can make bones,and vitamin E works as an antioxidant,getting rid of elements in the body that can damage cell.
Finally,from Vitamin K, we score the ability to clot blood,since it helps make the proteins that do this job.
Without this vitamin variety,humans face deficiencies that cause a range of problems, like fatigue, nerve damage, heat disorder, or diseases like rickets and scurvy.
On the other hand , too much of any vitamin can cause toxicity in the body,so there goes the myth that loading yourself with supplements in a great idea.
In reality, it's all about getting the balance right, and hitting that vitamin jackpot.

How does your brain respond to pain?

Let's say that it would take you ten minutes to solve this puzzle.
How long would it take if you received constant electric shocks to your hands?
Longer, right?
Because the pain would distract you from the task.
Well, maybe not; it depends on how you handle pain.
Some people are distracted by pain.
It takes them longer to complete a task, and they do it less well.
Other people use tasks to distract themselves from pain, and those people actually do the task faster and better when they're in pain than when they're not.
Some people can just send their mind wandering to distract themselves from pain.
How can different people be subjected to the exact same painful stimulus and yet experience the pain so differently?
And why does this matter?
First of all, what is pain?
Pain is an unpleasant sensory and emotional experience, associated with actual or potential tissue damage.
Pain is something we experience, so it's measured by what you say it is.
Pain has an intensity; you can describe it on a scale from zero, no pain, to ten, the most pain imaginable.
But pain also has a character, like sharp, dull, burning, or aching.
What exactly creates these perceptions of pain?
Well, when you get hurt, special tissue damage-sensing nerve cells, called nociceptors, fire and send signals to the spinal cord and then up to the brain.
Processing work gets done by cells called neurons and glia.
This is your Grey matter.
And brain superhighways carry information as electrical impulses from one area to anther.
This is your white matter.
The superhighway that carriers pain information from the spinal cord to the brain is our sensing pathway that ends in the cortex,a part of the brain that decides what to do with the pain signal.
Another system of interconnected brain cells called the salience network decides what to pay attention to.
Since pain can have serious consequences, the pain signal immediately activates the salience network.
Now, you're paying attention.
The brain also responds to the pain and has to cope with these pain signals.
So, motor pathways are activated to take your hand off a hot stove, for example.
But modulation networks are also activated the deliver endorphins and enkephalins,chemicals released when you're in pain or during extreme exercise, creating the runner's high.
These chemical systems help regulate and reduce pain. 
All these networks and pathways work together to create your pain experience, to prevent further tissue damage, and help you to cope with pain.
This system is similar for everyone, but the sensitivity and efficacy of these brain circuits determines how much you feel and cope with pain.
This is why some people have greater pain than others and why some develop chronic pain that does not respond to treatment, while others respond well.
Variability in pain sensitivities is not so different than all kinds of variability in responses to other stimuli.
Like how some people love roller coasters, but other people suffer from terrible motion sickness.
Why does it matter that there is variability in our pain brain circuits.
Well, there are many treatments for pain, targeting different systems.
For mild pain, non-prescription medications can act on cells where the pain signals start.
Other stronger pain medicines and anesthetics work by reducing the activity in pain-sensing circuits or boosting our coping system, or endorphins.
Some people can cope with pain using methods that involve distraction, relaxation,meditation, yoga, or strategies that can be taught, like cognitive behavioral therapy.
For some people who suffer from severe chronic pain, that is pain that doesn't go away months after their injury should have healed, none of the regular treatments work.
Traditionally, medical science has been about testing treatments on large groups to determine what would help a majority of patients.
But this has usually left out some who didn't benefit from the treatment or experienced side effects.
Now, new treatments that directly stimulate or block certain pain-sensing attention or modulation networks are being developed, along with ways to tailor them to individual patients, using magnetic resonance imaging to map brain pathways.
Figuring out how your brain responds to pain is the key to finding the best treatment for you.
That's true personalized medicine.

Where do genes come from?

You have about 20,000 genes in your DNA.
They encode the molecules that make up your body, from the keratin in your toenails, to the collagen at the tip of your nose, to the dopamine surging around inside your brain.
Other species have genes of their own.
A spider has genes for spider silk.
An oak tree has genes for chlorophyll, which turns sunlight into wood.
So where did all those genes come from?
It depends on the gene.
Scientists suspect that life started on Earth about 4 billion years ago.
The early life forms were primitive microbes with a basic set of genes for the basic tasks required to stay alive.
They passed down those basic genes to their offspring through billions of generations.
Some of them still do the same jobs in our cells today, like copying DNA.
But none of those microbes had genes for spider silk or dopamine.
There are a lot more genes on Earth today than there were back then.
It turns out that a lot of those extra genes were born from mistakes.
Each time a cell divides, it makes new copies of its DNA.
Sometimes it accidentally copies the same stretch of DNA twice.
In the process, it may make an extra copy of one of its genes.
At first, the extra gene works the same as the original one.
But over the generations, it may pick up new mutations.
Those mutations may change how the new gene works, and that new gene may duplicate again.
A surprising number of our mutated genes emerged more recently; many in just the past few million years.
The youngest evolved after our own species broke off from our cousins, the apes.
While it may take over a million years for a single gene to give rise to a whole family of genes, scientists are finding that once the new genes evolve, they can quickly take on essential functions.
For example, we have hundreds of genes for the proteins in our noses that grab odor molecules.
The mutations let them grab different molecules, giving us the power to perceive tirllions of different smells.
Sometimes mutations have a bigger effect on new copies of genes.
They may cause a gene to make its protein in a different organ, or at a different time of life, or the protein may start doing a different job altogether.
In snakes, for example, there's a gene that makes a protein for killing bacteria.
Long ago, the gene duplicated and the new copy mutated.
That mutation changed the signal in the gene about where it should make its protein.
Instead of becoming active in the snake's pacreas, it started making this bacteria-killing protein in the snake's mouth.
So when the snake bit its prey, this enzyme got into the animal's wound.
And when this protein proved to have a harmful effect, and helped the snake catch more prey, it became favored.
So now what was a gene in the pancreas makes a venom in the mouth that kills the snake's prey.
And there are even more incredible ways to make a new gene.
The DNA of animals and plants and other species contain huge stretches without any protein coding genes.
As far as scientists can tell, its mostly random sequences of genetic gibberish that serve no function.
These stretches of DNA sometimes mutate, just like genes do.
Sometimes those mutations turn the DNA into a place where a cell can start reading it.
Suddenly the cell is making a new protein.
At first, the protein may be useless, or even harmful, but more mutations can change the shape of the protein.
The protein may start doing something useful, something that makes an organism healthier, stronger, better able to reproduce.
Scientists have found these new genes at work in many parts of animal bodies.
So our 20,000 genes have many origins, from the origin of life, to new genes still coming into existence from scratch.
As long as life is here on Earth, it will be making new genes.

Cell vs. virus: A battle for health

You're in line at the grdcery store when, uh on, some one sneezes on you.
The cold virus is sucked inside your lungs and lands on a cell on your air way lining.
Every living thing on Earth is made of cells, from the smallest one-celled bacteria to the giant blue whale to you.

Each cell in your body is surrounded by a cell membrane, a thick flexible layer made of fats and proteins, that surrounds and protects the inner components.
It's semipermeable, meaning that it lets some thing pass in and out but blocks others.
The cell membrane is covered with tiny projections.
They all have functions, like helping cells adhere to their neighbors or binding to nutrients the cell will need.

Animal and plant cells have cell membranes.
Only plant cells have a cell wall, which is made of rigid cellulose that gives the plant structure.
The virus cell that was sneezed into your lungs is sneaky.

Pretending to be a friend, it attaches to a projection on the cell membrane, and the cell brings it through the cell membrane and inside.
When the virus gets through, the cell recognizes its mistake.

An enemy is inside! Special enzymes arrive at the scene, and chop the virus to pieces.
They then send one of the pieces back through the cell membrane, where the cell displays it to warn neighboring cells about the invader.
A nearby cell sees the warning and immediately goes into action.
It needs to make antibodies, proteins that will attack and kill the invading virus.

This process starts in the nucleus.
The nucleus contains our DNA, the blueprint that tells our cells how to make everything our bodies need to function.

A certain section of our DNA contains instructions that tell our cells how to make antibodies.
Enzymes in the nucleus find the right section of DNA, then create a copy of these instructions, called messenger RNA.
The messenger RNA leaves the nucleus to carry out its orders.
The messenger RNA travels to a ribosome.
There can be as many as 10 million ribosomes
in a human cell, all studded along a ribbon-like structure called the endoplasmic reticulum.
This ribosome reads the instructions from the nucleus.
It takes amino acids and links them together one by one creating an antibody protein the will go fight the virus.

But before it can do that, the antibody needs to leave the cell.
The antibody heads to the golgi apparatus.
Here, it's packed up for delivery outside the cell.
Enclosed in a bubble made of the same material as the cell membrane, the golgi apparatus also give the antibody directions, telling it how to get to the edge of the cell.
When it gets there, the bubble surrounding the antibody fuses of the cell membrane.
The cell ejects the antibody, and it heads out to track down the virus.
The leftover bubble will be broken down by the cell's lysosomes and its pieces recycled over and over again.

Where did the cell get the energy to do all this?
That's the role of the mitochondria.
To make energy, the mitochondria takes oxygen, this is the only reason we breathe it, and adds electrons from the food we eat to make water molecules.
That process also creates a high energy molecule, called ATP which the cell uses to power all of its parts.

Plant cells make energy a different way.
They have chloroplasts that combine carbon dioxide and water with light energy from the sun to create oxygen and sugar, a form of chemical energy.
All the parts of a cell have to work together to keep things running smoothly, and all the cells of your body have to work together to keep you running smoothly.
That's a whole lot of cells.

Scientists think there are about 37 trillion of them.

How does the heart pumps blood?

For most of history, humans had no idea what purpose the heart served.
In fact, the organ so confused Leonardo da Vinci, that he gave up studying it.Although every one could feel their own heart beating, It wasn't always clear what each thump was achieving.
Now we know that the heart pumps blood.
But that fact wasn't always obvious, because if a heart was exposed or taken out, the body would perish quickly.
It's also impossible to see through the blood vessels, and even if that were possible, the blood itself is opaque, making it difficult to see the heart valves working.
Even in the 21st century, only a few people in surgery teams have actually seen a working heart.Internet searches for heart function, point to crude models, diagrams or animations that don't really show how it works.
It's as if there has been a centuries old conspiracy amongst teachers and students to accept that heart function cannot be demonstrated.
Meaning that the next best thing is simply to cut it open and label the parts.That way students might not fully grasp the way it works, but can superficially understand it, learning such concepts as the heart is a four-chambered organ, or potentially misleading statements like, mammals have a dual-circulation: one with blood going to the lungs and back, and another to the body and back.
In really, mammals have a figure-eight circulation.
Blood goes from one heart pump to the lungs, back to the second heart pump, which sends it to the body, and then back to the first pump.
That's an important difference because it marks two completely different morphologies.
This confusion makes many students wary of hart in biology lessons, thinking it signals an intimidating subject full of complicated names and diagrams.
Only those who end up studying medicine completely understand how it all actually works.That's when its functions become apparent as medics get to observe the motion of the heart's valves.
So, let's imagine you're a medic for a day.
What you'll need to get started is a whole fresh heart,  like one from a sheep or pig.
Immerse this heart in water and you'll see that it doesn't pump when squeezed by hand.
That's because water doesn't enter the cleanly enough for the pumping mechanism to work.
We can solve this problem in an extraordinary simple way .Simply identify the two atria and cut them off, trimming them down to the tops of the ventricles .
This makes the heart look less complicated because the atria have several incoming veins attached.  So, without them there, the only vessels remaining are the two  major heart arteries: the aorta and pulmonary artery, 
Which rise like white columns from between the ventricles.
It looks --and really is--very simple.If you run water into the right ventricle from a tap
(the left also works, but less spectacularly), you'll see that ventricular valve tries to close against the incoming stream.
And then ventricle inflated with water.
Squeeze the ventricle and a stream of watersquirts out of the pulmonary artery.
The ventricular valves, called the tricuspid in the right ventricle and the mitral in the left, can be seen through the clear water opening and closing like parachutes, as the ventricle is rhythmically squeezed.
This flow of water mimics the flow of blood in life. 
The valves are completely efficient.
You'll notice they don't leak at all when the ventricles are squeezed.Over time, they also close against each other with very little wear and tear, which explains how this mechanism continues to work seamlessly for more than 2 billion beats a heart gives in its lifetime.
Now, anyone studying the heart can hold one in their hands, make it pump real
and watch the action unfold.
So place your hand above your own and feel its rhyme beat.Understanding how this dependable inner pump works gives new resonance to the feeling you get when you run a race, drink too much caffeine or catch the eye of the one you love.