The Marshall's blog

  🧠 Your Body Is Secretly Running a Medical System Without You Knowing Your body isn’t just a biological machine. It’s a fully automated, self-repairing, decision-making system that operates 24/7… without asking you once. Let’s dive into some MBBS-level realities that sound unreal but are completely true. ❤️ 1. Your Heart Has Its Own Nervous System The heart isn’t just a pump. It has a mini-brain called the cardiac nervous system that can: send signals to your brain regulate rhythm independently That’s why even outside the body, under the right conditions… 👉 the heart can still beat. ⚡ 2. Your Brain Runs on Electricity Your brain generates enough electrical activity to: 👉 power a small light bulb 💡 Every thought, memory, and emotion = electrical signals firing between neurons. You’re basically a living bio-electric system. 🩸 3. Your Blood Travels 19,000 km Every Day In just one day, your blood covers a distance close to: 👉 19,000 kilometers That’...

How the SA Node Generates Electricity 💗💗💗 Deep within the right atrium of the human heart sits a structure no larger than a grain of rice. This cluster of specialized cells is called the sinoatrial node , often shortened to the SA node . Despite its size, it performs one of the most essential jobs in biology: it acts as the heart’s natural pacemaker. The remarkable part is that the SA node does not receive electrical commands from the brain to start each heartbeat. Instead, it creates its own electrical impulses . Where the Electricity Comes From The “electricity” of the heart is not like power flowing through wires in a wall. It is generated by charged particles called ions moving across cell membranes. Inside heart cells, the concentrations of ions such as sodium (Na⁺), calcium (Ca²⁺), and potassium (K⁺) are carefully controlled. The cell membrane acts like a gatekeeper with specialized channels that allow these ions to move in and out. In most heart muscle cells, these channels...

The Evolutionary Mismatch  Between the Human Brain and the Internet | Cognitive Science | Digital Behavior Abstract The internet has changed the way we live and think. Our brains developed in a world with information and small social groups. Now we are exposed to a lot of information, social media and digital distractions. This essay explores how our brains interact with the world and how it affects our attention, memory, motivation and well-being. 1. Introduction For thousands of years humans lived in groups with limited information. Our brains developed to focus on things detect threats and build relationships.. The digital world is different. We now have access to a lot of information, social media and digital distractions. This change raises a question: what happens when our brains meet the world? 2. Evolutionary Architecture of Human Cognition Our brains are designed to adapt to our environment. We developed mechanisms to respond to challenges in our surroundings. In groups we...