PHYSIOLOGY - BASICS
The name itself gives a clue: physiology comes from the Greek words thesis meaning origin or
nature and logia meaning study. So, its essentially the study of the bodys natural processes.
And when we say human physiology, were focused specifically on the workings of you.
At its heart, physiology is driven by regulation and communication. Your body is a remarkably
well-coordinated system, relying on both speedy and slower communication pathways. Fast
communication routes are handled by neuronslike a lightning-fast messenger servicewhile
slower, more sustained signaling comes from the endocrine system, using hormones.
Lets zoom in on the fundamental building block: the cell. Youre not just made of one or two cells
youre a complex community of approximately 100 trillion cells Thats a truly mind-boggling
number, all working together to create a perfectly coordinated system.
Now, lets talk about the internal environment, sometimes called the milieu intrieur a French term
for internal environment. This is where things get really interesting. Our bodies are largely made
of water -- a whopping 60 of your body weight To give you a visual, if you weigh 100 kilograms
about 220 pounds, thats approximately 60 liters around 16 gallons of water.
That 60 liters is divided into two compartments:
Intracellular Fluid ICF: This is the fluid inside your cells. It makes up about two-thirds roughly 40
liters of that total water volume.
Extracellular Fluid ECF: This is the fluid outside your cells. Its one-third about 20 liters of the
total.
Imagine it like this: your cells are nestled within the ECF, which acts as their life-sustaining
environment. The ECF is, therefore, your bodys internal environment - thats why its called the
internal environment Its the fluid that cells live in and receive nutrients and eliminate wastes.
Essentially, physiology helps us understand how all these trillions of cells, connected by
communication networks, work together to maintain this stable internal environment and keep
you functioning perfectly
The name itself gives a clue: physiology comes from the Greek words thesis meaning origin or
nature and logia meaning study. So, its essentially the study of the bodys natural processes.
And when we say human physiology, were focused specifically on the workings of you.
At its heart, physiology is driven by regulation and communication. Your body is a remarkably
well-coordinated system, relying on both speedy and slower communication pathways. Fast
communication routes are handled by neuronslike a lightning-fast messenger servicewhile
slower, more sustained signaling comes from the endocrine system, using hormones.
Lets zoom in on the fundamental building block: the cell. Youre not just made of one or two cells
youre a complex community of approximately 100 trillion cells Thats a truly mind-boggling
number, all working together to create a perfectly coordinated system.
Now, lets talk about the internal environment, sometimes called the milieu intrieur a French term
for internal environment. This is where things get really interesting. Our bodies are largely made
of water -- a whopping 60 of your body weight To give you a visual, if you weigh 100 kilograms
about 220 pounds, thats approximately 60 liters around 16 gallons of water.
That 60 liters is divided into two compartments:
Intracellular Fluid ICF: This is the fluid inside your cells. It makes up about two-thirds roughly 40
liters of that total water volume.
Extracellular Fluid ECF: This is the fluid outside your cells. Its one-third about 20 liters of the
total.
Imagine it like this: your cells are nestled within the ECF, which acts as their life-sustaining
environment. The ECF is, therefore, your bodys internal environment - thats why its called the
internal environment Its the fluid that cells live in and receive nutrients and eliminate wastes.
Essentially, physiology helps us understand how all these trillions of cells, connected by
communication networks, work together to maintain this stable internal environment and keep
you functioning perfectly
