2 Months Before Step 1 Exam!

I am only 2 months away from Step 1 exam. This is crazy! My dream of becoming a doctor is going to come true very soon. Unfortunately, I have been struggling with Step 1 prep, especially on Uworld problem sets. The procrastination is real. My current plan is to finish off all the in class material and try to do at least 100-200 questions (that is about 3-4 blocks) per day. So far I am 90% done on Rx, about to start DIT sets, and about 20% done on Uworld!

This week has been tough for me. Not only because of the rejection letter I received from the MDPhD program, but also the lack of motivation that I had during the week. I missed 2 days of classes and I fell completely behind on the material. Thank God that this unit has been a lot of review for me at this point, so I am not too concerned :). For those of you who wish to enter medical school, it is okay to slack off here and there! Do make sure to have a plan to rebound back to where you were. Now I am at a coffee shop in downtown Salt Lake City taking a break from studying since 10am this morning. I also wish to start writing on this blog again as a personal journey towards becoming a cardiologist. This road is going to be long and tough but I am confident that I will succeed one day!

~KC

Three Layers of the Heart

Hello again and welcome back! Today I am going to talk to you about the tissue types within our heart.

Like other vessels, our heart is composed of three distinct layers: the epicardium, the myocardium, and the endocardium. Each of these layers have a different role for heart contraction. In this article, we are going to dissect each layer, and to understand the pathology that can happen within each of these layers.

The epicardium is used primarily for energy storage. In a human heart as illustrated above, you can see that there are a lot of fat surrounding the heart. The layer in which the fat sits on is the epicardial layer, hence the fat is call the epicardial fat. This fat not only serves as an energy source, it also helps to protect the heart form injury by acting like a cushion pad. Interestingly, our heart actually runs on fat under normal condition! However, when it is in trouble (such as during an heart attack), the heart switches its energy supply from fat to carbohydrates and glucose! Weird! Unfortunately, we do not know why that is and it is currently a very controversial and hot topic in research at many universities!

Facts:  Did you know that mice that are born with an excessive use of carbohydrates or glucose in the heart is less prone to developing congestive heart disease?

Next, the myocardium. This is where the action of the heart occurs. It is generally very thick and full of muscle fibers. As you can imagine, this is the place where contraction occurs. Our heart is run by calcium to produce contraction patterns. Therefore this layer is extremely well-perfused by the coronary vessels of the heart. Our blood has an abundance of calcium ion that ultimately getting uptake by the cardiomyocytes (the heart cells) via a structure call a T-tubule. This T-tubule is basically the freeway of our heart that connects the blood supply (trucks full of christmas presents) to each individual contractile cell (kids who are waiting for Santa Claus). As you can imagine, if the blood supply gets cut off such as in congestive heart failure, our heart muscle cells do not get enough calcium ion and nutrients, they start to die off! In other words, if our kids don't get their christmas present, they are going to make the parents very miserable and they start to break things around the house!

Facts: people who have big heart (hypertrophic or super muscular heart) is often indicative of diseases such as congestive heart failure, swelling of the lung (pulmonary edema), or liver failure.

Lastly, the endocardium is the innermost layer of our heart. It is responsible for releasing various hormones, cytokines (signaling molecules), and provide protection to the important inner structures of the heart. This is a 1 cell layer thick wall that can increase or decrease how leaky some of the vessels are within the heart. It has been shown that it forms a barrier to prevent toxins from building up inside the heart. It is also often the first site of getting infection from bacteria traveling through the blood!

Five Tissues Type Found Within Our Body

Welcome back everyone. Today I am going to talk about the tissue types found within our body before we continue to discuss the blood supply in our heart. There are 5 different type of tissues can be found within our body. They are organized as follows,

1. Connective and Supportive Tissue
These includes bones and fibrous tissues that connects and support two things together like cartilage and interosseus membrane between fibula and tibia. They support our body, aid in body movements and prevent our body from damaging itself from our daily activities.

Facts: Osteoporosis results because supportive tissues in our body is weakened or damaged. Bone, in this case, is where our body stores calcium to make hydroxyapitite, is weakened because of hormonal imbalanced or we are not ingesting enough calcium in our diet. Many implication may result from osteoporosis including bone fractures. On the other hand, arthritis is the inflammation of the joint due to the damages done on the articular cartilage between the bones. Since Articular cartilage is responsible to lubricate between the two bones along with synovial fluids found within the joint capsule. The loss of articular cartilage therefore induces inflammation within the joint and cause unbearable pain to that individual.

2. Hematolymphoid Tissue
This is the blood and lymph tissues that we always encounter in our daily lives. Their function is to transport stuff (nutrients and waste) into and out of our body. It also contains most of our immune responses within our body. This is where all the white blood cells, along with other regulatory proteins hang out and do most of their work.

Facts: Sickle cell anemia is a condition in which that our blood changes its shape and its affinity for oxygen. The lack of oxygen is a dangerous condition because it suffocates our organs and decreases the amount of oxidative phosphorylation happening in our cell, therefore our cells are unable to produce ATP and provide enough energy to drive chemical reactions in our body.

3. Muscle Tissue
Without a lot of scientific knowledge, we probably already know a lot about our muscle. There are three types of muscle tissues: cardiac tissue (the one we are most interested in), skeletal tissue and smooth muscle tissues.

Each tissue types are important for many functions and therefore are all essential for proper functioning of our body. First skeletal muscles are important for movements and generating heat to keep us warm. Cardiac muscle is important for regulating our heart beat and keeping a regular rhythm of our heart. Smooth mucle, on the other hand, is important for regulating vessel sizes and our digestive system.

Fact: atrial fibrillation results because our cardiac muscle cells are not regulated properly, therefore our atriums are not able to produce proper beating rhythm to push more blood into the ventricles of the heart. On the other hand, if our ventricle is not beating properly, in a condition called ventricular fibrillation, or V-fib, our entire heart does not beat properly, and the individual may result in death.

4. Nervous Tissue
The nervous tissues allows our organ to communicate with the brain and other structures of our body. It also allows outside stimulation to be transmitted into our body such as sound waves, light and sensational information. There are many types of nervous tissue found within our body.  It also the building units of our central nervous system, which consists of the brain and the spinal cord. There are several types of nervous tissues are particularly important: Multipolar neurons (Motor neuron) and pseudounipolar neurons (Sensory neuron).

Facts: Damage in the nervous tissue results in paralysis. The tibial nerve, located at the lower limb, is responsible for innervating the posterior compartment of our thigh and leg. If damaged, half of our lower limb will be paralyzed. Therefore severe injuries of nerves may cause paralysis of muscles as well as basic functioning of our body.

5. Epithelial Tissue
These are the covering for our body. Epithelial tissues protect our body from foreign invaders by providing a very hostile environment for bacteria and viruses. The different types of the epithelial tissues are summarized as follows:

Each of these tissues can be found at various parts of our body. Within our heart, we can also find each of these tissues types within the different compartments of our heart. Later on, I will covert the tissue types of our heart, including the three different layers of our heart surface and the inner compartments including valves and other anatomical structures found inside.

This is it for this week. Thanks for reading. If you have any questions, feel free to comment and I will try to respond asap. Have a good holiday!

StudentCardiologist,
Jeff

Basic Heart Anatomy- The Four Chambers

Hello everyone, welcome back to the student cardiologist. Today's topic is going to be on the anatomy of our heart. Before we begin, I want you to subscribe to my blog, which is located at the top right hand side of this web page. This blog can be served as a great reliable resource for you in understanding the materials that you learn in classroom or in your medically related training. Your subscription will also greatly motivate me to write more lecture materials to help you in whatever you do, either in school, work, or just for personal interest. Thank you!

Let's get started.

Our heart is a very sophisticated organ, in a biochemistry level as well as on the mechanical level. We all know that our heart is used for pumping blood and nutrients to the rest of our body, and to keep us alive.  But not many know that there are so many small components and chemical reactions happening to make this organ to have a consistent but controllable heartbeat. For example, the diagram below is just one signal processing pathway in our heart for cardiac muscle contraction, and it is amazing that it takes that much work and chemical and proteins to make our heart contracts at a regular or modifiable rate!!!

Like many other animals (Not all), our heart is consisted of 4 chambers, with  2 chambers on each side. There are a lot of blood vessels of different sizes attaching to each chamber like the aorta. These 4 chambers are called the atriums and ventricles. There are 1 atrium and 1 ventricle on each side of the heart, makes 2 atriums, 2 ventricles and 4 chambers in total. Atrium is a relatively small chamber compared to the ventricle  found within the heart. Their main functions were to receive blood from the veins, and pump additional blood from the atrium into the ventricles. This pumping action will therefore push the blood into the ventricle allow more blood to be delivered to different places of our body.

Ventricles, on the other hand, are used to pump blood either to the lung, so that the blood can be oxygenated, or to the rest of our body. The ventricles are a lot stronger than the atriums because they have to provide blood to a greater area. Imagine the ventricle has to pump blood from your heart to your toes while atrium is only from the top of the heart to the bottom! Therefore, when observed, they have a thicker wall, which tells us that there are a lot more cardiac muscles compare to the atrium.

Fun fact: amphibians only have 3 chambers and fish only have 2!!

For naming conventions, anatomists name the side of the atrium and the ventricle regarding to the patient's side. So, our right is their left, therefore it is the left atrium and left ventricle on the right hand side of the diagram. Below is a cadaver picture of a heart, which looks very close to heart illustration above.

So what happen when our ventricle chambers are not working properly?

One common defects that we will enter into is call V-fib, or ventricular fibrillation. This is a serious condition in which our ventricle wall muscle (cardiac muscle) is not coordinated, which means that they do not contract at the same time. This therefore provides a weak contraction that is not sufficient to pump blood across the body, which may essentially lead to cell death in organs if waited for too long. When that happens, we need to use the electrical defibrillator to "jump-start" the heart again. These defibrillator are the pads that we see in many hospital shows like "Grey's anatomy", "House" or "ER".

How about fibrillation at the atriums?

Since atriums are only responsible for pushing additional blood into the ventricles, a defect at the atriums are not as deadly as V-fib. A-fib, or atrial fibrillation are often controlled by using drugs that can help to maintain the rhythm of the atriums, to reduce symptoms like shortness of breath and irregular heartbeat.

Next time, we will be more specifically talking about the vessels that are drained into each of those chambers and how they are connected through arteries and veins. Ultimately, these arteries and veins come together to form a close loop circuit, or the collateral circuits that allow blood to flow through all the organs and return back to the heart. 

I will see you next time! Don't forget to subscribe :)

Jeff

Welcome!

Hi! Welcome to my personal blog. This is Jeff Lei, a student doctor from Utah. I just want to take a brief moment to introduce myself. I am originally from Macau, a small fishermen town in China, where I spent the first 16 years of my life living and going through primary schools. I moved to Salt Lake City five years ago in 2007 on Valentine's day to live with some of my relatives here in Utah. Thus far, it has been a very difficult and exciting journey to experience a different culture. Anyhow, I am currently going to school at the University of Utah studying biomedical engineering and chemistry in honors. I am also a pre-med student applying to various medical school.I love science, helping people, volunteering and interact with others. I also love to travel, play ping pong, music and experience new cultures.


Below are some of the pictures of my beautiful hometown in China :) This is the beautiful Macau tourist tower. It is 64 stores high, and it is one of the tallest buildings in Asia.

This is the Macau Grand Prix, beginning early November every year.

Macau is also known as the oriental Las Vegas, there are a lot of casinos, entertaining centers and shopping mall for everyone who enjoys nightlife and city life-style.

If you want to know more about Macau, or want to travel to Asia but don't know where to visit. Please leave a comment and I will let you know more :)

So, why do I want to build this blog? My dear friend Rinchen at the U has motivated me to start writing about things that I am very passionate in, which is the complex organ within each of us- the heart. I have researched in the area of cardiology as well as human genetics during the course of my undergraduate career. I have also studied different aspects of the heart, including electrical and mechanical makeup of our heart. I therefore want to spread the free knowledge to ones who are seeking for them, as well as meeting individuals who share similar interests. Also, during the course of my study, I realize scientists and engineers tend to use very complex terminologies to describe some very very simple phenomenon occurring inside our body. It is also my goal to simplify those terms so that the knowledge is accessible to everyone. Lastly, I will also share some of my experiences as a pre-med to those individuals who wish to understand the process of becoming a physician in the United States.

This is a student video featuring undergraduate research when I participated in research with Dr. Abel at the University of Utah . Enjoy!

This is all I have for you guys for now. Take care :)

Jeff