You may (or more likely, may not) have noticed that I did not do any “fun med facts” post during biochemistry. The class itself was fast-paced and seemed to go by so quick. We learned the ins and outs and specifics to so many processes that were interesting, and I loved learning about them, but it's just not possible to share everything.
I’ve thought some more about it, and I’ll be sharing three broad, interesting biochem topics in this post.
1. How does my immune system protect me?
Anything that causes an immune response is called an antigen. Antigens are on foreign material that can enter your body.
You have two main types of immunity to help protect your body.
1) Innate immunity – these are nonspecific lines of defense and will attack anything that's harmful to your body. They act immediately or within a few hours, and they are the first line of defense if something invades your body.
Here are what some of those cells look like (these are your white blood cells - and yes ,we had to recognize and count all of these in samples) :
2) Adaptive immunity – involves a line of defense that is specific to the antigen that is present within you. The antigen will be recognized and processed, and then your body will create a specific army of cells made to combat this specific antigen. In addition to making “army” cells that will fight, your body makes “memory cells” that will stay in circulation to remember what this antigen looks like, so that the next time it enters your body, the “army” can be quickly made to attack.
Flu vaccines* work by exposing you to the antigen without having you contract the disease that way your memory cells can be made so if you would ever be exposed to the specific flu antigen again, you would be able to quickly create and “army” and protect yourself from getting the disease.
Check this out:
Let’s say you get injected with antigen A at day 1 (red line), it has a small peak at day 7 and indicates 10 antibodies created. If you get injected at day 28 with the same antigen (red line), the peak is all the way at 10,000 antibodies and all of this occurred in a much faster time frame then it took to make the 10 antibodies from the day 1 exposure. Those antibodies are your defense against the virus or whatever bad thing is trying to harm you.
Notice that the purple line is a NEW antigen and if that’s injected at day 28 it does NOT make the antibodies as fast as antigen A did on day 28. That’s because this is your first exposure and you must have prior exposure to make that many antibodies that fast and effectively.
*Vaccines are more complicated than this, and there are more than just one type. I just wanted to show you an example.
2. How does cancer work?
Cells in your body have specific signals that tell them when to die, when to replicate, when to live, and when to grow. If any of these signals are messed up, or disturbed, cancer can form. What is cancer? It’s basically uncontrolled replication of cells. Cancer cells will divide when they should not, and will not die, when they should.
We have genes in our cells that control the signals that tell cells when to replicate and when to die. Mutations (the change in the correct structure of a gene) in these types of genes can disrupt those processes.
So what could cause mutations in those genes? Age, genetic info from your parents, radiation (why sunscreen is important), chemicals (cigarette smoke, those fancy chemicals in plastics and specific processed foods people always try to scare you with).
Cancer cells are so powerful and can:
- replicate uncontrollably
- ignore signals that say “stop replicating”
- ignore signals that say “time for you to die”
- ignore signals that say “you’re an OLD cell, you need to die”
- invade other tissue cells (example: start in the skin, head to the brain)
- ignore immune cell responses (discussed in #1)
- create new vessels to supply the new cells.
The challenge then with treatment is to only kill the cancer cells and avoid the good cells.
3. What happens to our cells when we get old?
There's a specific number - it's called the Haflick limit - that determines how many times a cell can divide before it's done dividing and is gone forever. Age slows down signals that tell the cell to divide and more cells start dying this will lead to your body slowly, cell by cell, falling apart.
At the ends of our chromosomes we have something called "telomeres" that shorten with each time the cell replicates. When this gets too short (due to a TON of divisions, so in old age) and cells still try to divide, the chromosome ends (you have 46 chromosomes in each cell) can "stick" together and then the new cell is all sorts of genetically messed up...so cell signals will say "time to die."
Here's the fun part, cancer cells (85-90%) have been known to express an enzyme called telomerase that extends the length of telomeres ---so as you can guess, those cells will never get "sticky ends" and will resist dying at least in this pathway. So if we can stop this enzyme in these cancer cells, that's one way to target only the bad cells when treating cancer.
This core’s reflection isn’t as sentimental and heart felt as anatomy’s was (found here). I studied as long and hard as I could each day and prayed everything would be fine – and it was.
I did not buy a textbook, I barely attended lecture in person (I was an online viewer for most of the course – same thing, but I can speed up their voices to save time), and I still did pretty well in the course.
I bought “Rapid Review Biochemistry,” and looked at it every day, and found that it was very beneficial to determining the “important” parts of the material being covered. It helped especially when decided how much and what to memorize before the exams. I’ll be using it for my board prep as well. This book was highly recommended online from other med students, and for good reason.
For those interested here’s what a typical day looked like:
8:00 a.m. wake up, make coffee, brush teeth, eat breakfast, head to office
8:30 a.m. start reviewing yesterday’s material or material I’m struggling with
9:30 a.m. head to campus (if I need to go to histology lab, otherwise stay home and listen to lecture online)
10:00 a.m.-Noon Histology (microscope slide material) quiz and sit through a lecture about histology
12:00 p.m. eat a shake and fruit, and workout
1:00 p.m. head home, have a snack, start listening to the morning’s lectures
5:00 p.m. snack, study, and think about what to cook for dinner
6:00 p.m. cook and eat dinner
6:30 p.m. study
8:30 p.m. shower, do flashcards, watch TV, read a book (If Jake’s home – I’d stop studying and hang with him)
P.S. Excited to try out some new ideas on the blog for 2015! Also, check out the links above to explore older posts, because I recently spent some time reworking the buttons to include more posts in the archives!