Hey guys, it's Metacos'Perfectionellus. Welcome to my new series on physiology. Today's topic is an introduction to the great field of physiology. So, let's get started.
So, let's break this word down. Physiology. from the Greek words thesis and logia.
Thesis means origin or nature. Logia means the study of. But we are not talking about every kind of physiology.
We are talking about human physiology because this is called medicosis perfectionalis. Let's define human physiology. It's the study of function of the human body and its mechanisms. So anatomy was the study of structure, physiology is the study of function.
Not only function, the mechanism by which we carry out this function. Physiology is all about regulation and communication. Your body is well regulated and it has excellent communications. You have fast communications through the neurons and slow ones through the endocrine system. As you know the cell is the basic living unit or the building block of your body.
How many cells do you have? Around 100 trillion cells. That's amazing. Just think about that.
Your body, a coordinated solution. Let's talk about the internal environment or as they say it in French, milieu interieux. So your body has 60% its weight just water.
This 60% is subdivided into the intracellular compartment which is inside your cells and it's 2 thirds of the 60% and the rest is the extracellular fluid outside of your cell and this is 1 third of the 60%. Suppose that your weight is 100 kilograms 60 kilograms will be waters which is equal 60 liter because the density of water is one. Hello physics. So intracellular is two thirds of the 60 liters which is about 40 liters. The extracellular is the rest which is 20 liters.
Total is 60. Make sense? Your cells literally live in the extracellular fluid. These are your cells and here is the extracellular fluid surrounding the cells.
That's why we call the extracellular fluid the internal environment. The ECF is the internal environment. What's the ECF?
It's water, of course, with ions, oxygen, nutrients, and the bad stuff, the waste products. So we have the good stuff and the bad stuff. Ions such as sodium, chloride and bicarbonate. Nutrients such as amino acid, fatty acids and glucose.
The building blocks of protein, fat and carbs. Waste products, CO2 which is going to go to the lung to be exhaled out and some other garbage stuff going to the kidney to be excreted in the form of urine. Back to our story of the ECF.
ECF is circulating in your blood, coming out of your heart in a vessel called an artery, then to the capillaries, and then there is diffusion to the tissue, and then back to the vein, and then back to the heart, and this is the cycle of the ECF. In other words, the ECF is everywhere. That's why it's the internal... milieu. Now let's turn our attention to the intracellular fluid.
What's inside the cell? Again water with ions. But different types of ions.
You have potassium, magnesium, phosphate ions. This is different from the extracellular fluid which had sodium, chloride and bicarbonate. These are different stuff. Now, I'm not saying that you will never find sodium in the cell. No.
I'm just saying that sodium is more common outside of the cell than inside. By the same token potassium can also be found outside of the cell. It's just more common intracellularly. These ions keep flowing in and out, in and out, they are regulated.
We call this ion concentration. difference and we will talk about that later. In the next video we will talk about homeostasis not to be confused with hemostasis. These are totally different. So I strongly urge you to subscribe and hit the bell to get notified when I release my next video on homeostasis.
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As always, be safe, stay happy, and study hard.