Let’s Get The Basics Right
An introduction to 'Basics Matter': the new series taking you on a guided tour of the human body, and teaching you everything you need to know.
Hello! Welcome to Basics Matter, a brand new 6-month series in which we will explore the main systems of the human body, allowing you to understand how your amazing biology works, what your body is actually telling you, and all the things you can do to take good care of it.
This is a big movement based on professional conviction that prevention can be taught and learned. As a doctor, I am convinced that our good, professional, and empathic communication will always mark a profound difference in a person’s life. And this is what I’m here to do.
Now, like I said in this email (where I explained the Feel Good 2025 Plan), this year will be a Foundational Year. And today, as we take off with our Basics Matter series, we are setting the foundations of everything you will be learning throughout the next six months.
Here’s a general overview:
We will explore the main six systems of the human body, diving into one system per month, including (in no particular order):
Nervous system
Digestive system
Cardiovascular system
Respiratory system
Endocrine system (hormone control centre)
Musculoskeletal system
Each month, you will receive two in-depth special editions where you will learn:
What are the main organs in each system of the human body?
How do these systems work?
How do systems communicate with each other?
How do these systems sustain you?
How can you take good care of your organs and each system?
How can the healthy function of your systems and organs impact your future?
Basically, I’m going to teach how not to go to the doctor.
(Kidding! But not really. This knowledge will help you better understand your body, take good care of your health, and communicate more efficiently with your healthcare providers. If this is not a game-changer, I don’t know what it is!)
Are you ready to step up and take control of your mind and body, creating a rock-solid foundation for your health and wellbeing that you can build upon for years to come? Good!
Today we begin with a small introduction to get your feet grounded in this fascinating world of the marvellous Human Body. I am about to give you a lovely, general overview of what our human biology entails as we set the foundation of everything you are going to learn through this season.
Six human body systems in six months–off we go!
Let’s Get The Basics Right
First things first.
The human body is a single structure made up of billions of smaller structures of four major kinds: cells, tissues, organs, and systems.
A cell is a very small unit (like a compartment surrounded by a wall) that can live on its own, and serves as a building block to form larger structures. Cells make up all living organisms. They are formed of three main parts: a wall called membrane, a nucleus, and cytoplasm. They’re also incredibly smart and independent. They work in a way that allows them to absorb and use nutrients, create energy, distribute supplies to other neighbouring cells, they help each other, and they communicate too. It’s an amazing community in fact.
And guess what? We are made up of cells. Trillions of them! Here’s a drawing of a cell…you might remember them from Science class, maybe in school or in high-school?
In the origins of YOU, there were just two cells (mum’s and dad’s). These two cells combined and started multiplying like crazy, through a process called Mitosis. Two cells become four, then eight, then sixteen, then thirty two. This round mass of 32 cells is called a Morula. It takes around four days after fertilisation to go from two cells to Morula, as you can see in the image below. (And also in this video.)
(Fun fact: in Spanish, ‘Mora’ means blackberry. Funny enough, the Morula looks like a Mora! In fact, the word morula comes from the Latin word ‘morum’, which means mulberry.)
From this stage onwards, cells keep dividing into hundreds of cells, then thousands, then…countless! All this happens in a woman’s fallopian tubes—the pathway between the ovaries and the uterus.
When the morula is ready, it travels from the fallopian tube to the uterus to find the spot where it will stick to the wall and set roots. Cells continue their journey towards becoming specialised into their unique biological functions. Slowly and steadily, a fetus is being formed by this process of cell division and specialisation. Nine months later, a tiny human body is fully in place.
The branch that studies all these processes is called Embryology, and it’s probably one of the most fascinating signatures I remember studying during my career. My dad is a Veterinarian Doctor and he took a doctoral degree in this precise branch. I remember attending his classes while also going through med school. It was incredible how similar the processes between humans and all other animal species are when it comes to the very core of how we are all formed.
Anyways, back to us.
During the specialisation process, cells become clear on what specific functions they will have to do. Some of them will become muscle cells, others will become brain cells, digestive cells, blood cells, heart cells, bone cells, and so many more. When cells of a specific type get together, they form a tissue. Tissues will grow, and expand, giving way to the next job in the process: building organs, such as the stomach, the bowels, the liver, the pancreas, the thyroid, the heart, and the brain.
When organs are formed, they learn to connect with each other. There are many ways to do this: via signals from the brain—considered the control tower, or via particles (like hormones and neurotransmitters) that travel through the body from one place to another sending signals, more like messenger birds or like Harry Potter’s owl who delivers letters. These particles are incredibly smart, and they know exactly what to do and where to go. It’s difficult to imagine how all this happens so in tune, but it does. That’s the marvel of nature and biology.
When organs are formed and start communicating with each other, they realise that they are connected to some organs more than others, based on the functions they perform. For example, the stomach and the bowels are very well connected with each other, because of their work: digestion. The gall bladder and the pancreas are also connected to them, because they serve in the digestion process too.
Another example of interconnectedness between organs is the brain. The brain is a vast and complex electric system within our bodies. The electric pathways (called nerves) connect the brain with the muscles for example, allowing us to move our limbs, to walk, to eat, and perform many other voluntary and involuntary movements.
Eventually, a union of organs working towards the same goal and function is what we call a System. In the human body, there are many systems. Among the main ones we have: respiratory, digestive, skeletal, nervous, lymphatic, cardiovascular, endocrine, urinary, reproductive. Can you recognise any of these names? I bet you can!
Each of these systems work in a unique way, making the body an incredibly self-sustaining, independent unit that functions thanks to the integrated work of each system, formed by several organs, who in turn are formed by thousands of cells.
‘These systems break down food to create fuel, clear away waste, repair damaged tissues and DNA, fight infectious germs, and monitor the outside world so we can move through it safely.’ (Source: Live Science)
In the same way that cells are independent units who live on its own, you are also a vast, independent unit filled with organs, and protected by a very smart wall called Skin.
I hope you can grasp the bigger picture by now. Amazing, right?
Now, we’re almost done with today’s introductory theme. But before we finish, I’d love to give you some vocabulary and keywords to get familiar with, as we will dive into more of these concepts throughout the next six months of teaching you the human body basics.
Human Body Vocabulary
Read calmly through this list, and visit it as many times as needed. If you have any questions about any of these keywords, feel free to ask me in the comments, or email me at thefeelgoodlife@substack.com.
Let’s go!
Cell: The smallest living unit of the body.
Tissue: A group of similar cells that work together. Tissues are a level of organisation in living things, between cells and organ systems.
Organ: A body part made of a group of different tissues that work together for the same purpose. Examples: brain, eye, heart, stomach, kidney.
System: a group of organs, tissues, and muscles that work together to perform a specific function. The human body has many systems, including the circulatory, digestive, muscular, nervous, and respiratory systems.
Nervous System: the body's communication network that controls all of its functions. It's made up of the brain, spinal cord, and nerves.
Respiratory System: a group of organs that help you breathe in oxygen and breathe out carbon dioxide.
Digestive System: system in the body responsible for breaking down food into nutrients and energy that the body can use.
Cardiovascular System: a network of blood vessels and the heart that carries oxygen and nutrients to the body's cells. It also removes waste from the body.
Endocrine System: a group of organs involved with sending messages throughout the body as hormones.
Musculoskeletal System: the combination of bones, muscles, joints, ligaments, tendons, and cartilage that gives the body its structure, movement, and stability.
Abdomen: the middle part of the front of your body, between your chest area and your hips.
Mouth: the opening in the face through which one eats, breathes, and makes sounds.
Esophagus: tube connecting the mouth to the stomach; transports food
Stomach: organ where food is broken down.
Bowel or intestines: internal organs that look like tubes, which are responsible for breaking down the food, absorbing nutrients and making energy from it.
Poop: the waste left over after the body digests food. It's also known as stool or feces.
Anus: the opening where your poop comes out. In other words, it's the hole in your bottom.
Liver: the largest solid organ in the body that cleans blood and produces bile that helps in digestion. Is located under the right ribs.
Pancreas: flat, long organ behind your stomach that helps with digestion and regulates blood sugar. It's part of both the digestive and endocrine systems.
Lungs: organs responsible for breathing; they exchange oxygen and carbon dioxide. We have two and they’re located right inside your rib cage.
Heart: a muscle that pumps blood throughout the body. It's located in the middle of the chest, between the lungs.
Blood: Red fluid that circulates through the body's vessels, carrying oxygen and nutrients to the cells. It also removes waste products and fights infection.
Blood vessel: A tube that carries blood to different organs and tissues. Examples: arteries, capillaries, veins.
Artery: A blood vessel that carries blood with oxygen from the heart to tissues and organs
Vein: a blood vessel that carries blood back to the heart.
Bone: A rigid organ that gives structure to the body and contains bone marrow
Bone Marrow: a soft, spongy tissue in the center of most bones that produces blood cells, defense cells, and platelets.
Muscle: soft, flexible tissues that help you move and support your body. They are made of protein and are found throughout the body.
Joints: a place in the body where two or more bones meet, allowing for movement.
Brain: the most complex organ in the body, and it controls almost everything you do. It's responsible for thought, memory, emotion, and movement.
Spine: the backbone, or the column of bones that runs from the base of the skull to the tailbone, and protects the spinal cord connected to the brain.
Neurons: cells of the brain.
Nerves: bunch of wires or cables that send signals to and from the brain.
Glands: organs that makes one or more substances, such as hormones, digestive juices, sweat, tears, saliva, or milk. These substances can be used in the body or eliminated.
Hormones: chemicals that coordinate different functions in your body by carrying messages through your blood to your organs, skin, muscles and other tissues. These signals tell your body what to do and when to do it.
Lymph Nodes: little round or bean-shaped bumps that you usually can't feel unless they become swollen. Lymph nodes are like filters that remove germs that could harm you.
Ovary: a female reproductive organ that produces eggs and hormones. Biologically, every woman should have two ovaries, located on the upper sides of the uterus.
Uterus: hollow, pear‑shaped organ in a woman’s pelvis which plays an important role in in menstruation, fertility and pregnancy.
Testicles: the part of the reproductive system in men and people assigned male at birth (AMAB) that makes sperm and hormones. They're located outside your body.
Prostate: gland in the male reproductive system that produces fluid that helps with fertility. It’s the size of a walnut.
Circulation: the movement of blood through the heart and blood vessels of the body. it takes less than 1 minute to pump blood to every cell in your body.
Digestion: process that allows your body to get the nutrients and energy it needs from the food you eat.
Endocrine: refers to the glands that produce hormones–chemical messengers that travel through the blood to control the body's functions.
Okay! We’re done for today. I hope this has been clear, fun, and easy enough for you to understand. As you might’ve noticed, I like teaching in very simple terms, avoiding medical jargon as much as possible—it will always be the case, so no worries! If you have any doubts, please drop them in the comments so I can clear them for you. This way, other readers can learn too.
The foundation has been set and our new series ‘Basics Matter’ has officially begun!
The next newsletters, where we dive into the first human body system are ready to access! Right here:
This is Your Nervous System | Part 1
This is Your Nervous System | Part 2
Much love and talk soon,
Dr. Mariana
Image Credits: Freepik
This was such a fun read! Reminds me a bit of an animated series I watched (fortuitously) right before the pandemic called “Cells at Work!” Can’t wait to keep reading.
What a thorough, fantastic post. Thanks, Dr. Mariana!