Exam 3 scores are up!

The scores for exam 3 are back already, and I just posted them on Canvas. You did really well, as always…here are the stats:

Total points: 46
Mean: 41.8
SD: 3
High score: 46
Low score: 30

It was REALLY REALLY nice to have all of you in class this semester 🙂 I’m happy I don’t have to say goodbye (I have you again for Pathology starting in May of this year, at which time you’ll be D2s!!).

Please feel free to stop up and visit any time (I’m in 16-206), whether it’s to check out your last exam, or just to talk. I’m still your (stand-in) mom, whether I have you in class or not!

Exam scores are up!

Exam scores are back, finally! I don’t know what the holdup was – but they’re up now.

You guys did REALLY WELL. Here’s some stats, before adding a point (see below):

  • Mean: 46 (out of 49)
  • SD: 2.47
  • High score: 49
  • Low score: 34

All the questions except one performed really well (between 90-100% of the class got them right). The question that gave you guys trouble was this one:

Blood cells leave the marrow, circulate in the blood for a certain period of time, and eventually are removed from the blood. The cells that spend the longest amount of time in the blood are _____, and the cells that are in the blood for the shortest period of time are ______.

A. Platelets; neutrophils
B. Erythrocytes; platelets
C. Neutrophils; erythrocytes
D. Neutrophils; platelets
E. Erythrocytes; neutrophils

The correct answer was E (erythrocytes last about 4 months in the blood, platelets last around a week, and neutrophils are only in the blood a few hours before they exit into tissues). The class was about split between B and E, and I’m assuming it’s because I didn’t teach the point well enough.

I’m adding a point to everyone’s score for this question – so if you got them all right, you’ll see that your score is now 50/49.

You need your sleep. Really.

We talked a bit about the “glymphatic” system in the brain in class a while ago – and I wanted to share the TED talk I mentioned here, because it’s super interesting and super important. It’s sparked a flurry of research activity around the connections between lack of sleep and certain diseases, such as Alzheimer disease.  As Jeff Iliff explains, it turns out that while we sleep, the brain is not just sitting there doing nothing. Something very important happens in the brain during sleep – and it does not happen during waking hours.

The brain does more than clean itself during sleep, though. We know a TON more about sleep than we did even a few years ago – even about things that seem as incomprehensible as why we dream (fascinating!!).

Matthew Walker is one of the biggest names in sleep research, and his most recent book, “Why We Sleep,” is an easy and fun read (the audiobook is also excellent).

Or, for a more condensed version of his research, check out his conversation with Joe Rogan:

Lots of interesting facts, way beyond the typical “turn your phone off an hour before bed” stuff. For example: the World Health Organization has classified shift work as a probable carcinogen, based on the overwhelming research evidence that insufficient sleep is linked to significantly increased risk of certain types of cancer (colon, prostate, and breast). Yikes.

Here’s a really short video he put together that sort of summarizes all the bad things that happen if you don’t get enough sleep:

How to become 2.5 years younger

THIS is cool. And it involves the thymus, so it lines up well with our lectures!

Nature published a news article on September 5th entitled “First Hint that Body’s ‘Biological Age’ Can Be Reversed.” It summarizes a study in which the biological age of a small group of subjects actually reversed (yeah, you read that right, reversed!) following a year-long protocol involving three common drugs.

The study’s initial purpose was to see if drug therapy could stimulate regeneration of thymic tissue (remember how we said the thymus is biggest at puberty and gets smaller and smaller as you age?). But along the way, the researchers figured, hey, let’s also measure some methylation sites on the subjects’ DNA to see whether the treatment also affects epigenetic markers of aging.

Turns out the answer was yes on both counts: the subjects’ thymuses got bigger, and according to the DNA studies, the patients appeared an average of 2.5 years younger than when they started!

Okay, this is a small study, and it’s multifaceted, and there are always unintended/potentially dangerous side effects with drugs. STILL. SO COOL.

Fun Histology Instagram

I stumbled across this histology Instagram account called IQuizHisto and thought I’d share it with you. It’s basically a bunch of histology slides with little pointers asking you what things are (and then you can swipe and see the answers). Most of it is at about the same level of detail as we go into in our course – so you might find it useful.

Exam 1 grades are posted!

The scores for Exam 1 are now posted on Canvas. There were some issues with the scoring that took a while to sort out – but those have finally been resolved.

You guys did GREAT! The mean was 52.53 (out of 56 points), and the standard deviation was 2.6.

There was one question that didn’t perform well – it was this one, about lipofuscin:

51. What is lipofuscin?
A. Melanin granules in neurons in certain brain regions
B. A microfilament present in axons
C. Brown granules that result from breakdown of blood
D. A harmless cellular pigment that accumulates with age
E. Oxidized fatty acids that accumulate when myelin is digested

The best answer is D – but only 49% of the class answered correctly, so either this point wasn’t stressed enough in lecture, or there was a problem with the question itself, or (most likely) both.

Lipofuscin was discussed on slide 16 of the Nerve Tissue ppt:

It’s is a brownish pigment (that’s the -fuscin part of the name) that contains undigested normal cellular breakdown products, some of which are lipid in nature (that’s the lipo- part). It’s totally harmless, and it accumulates with age.

I can see why you might have chosen E (Oxidized fatty acids that accumulate when myelin is digested), since fatty acids are lipids. However, myelin is only broken down and digested in certain disease states – so it wouldn’t make up the debris in lipofuscin (which is normal). Plus, lipofuscin is seen in all kinds of organs (so myelin can’t be its main component). We didn’t specifically cover those facts, though – so I can’t really hold you accountable for that.

I can also see why you might have chosen D (Brown granules that result from breakdown of blood), since lipofuscin is brown! However, red blood cells only break down and accumulate as a pigment when something is wrong (for example, there’s a big bleed and all that blood needs to be resorbed). However, in hindsight, that wasn’t something I should have expected you to know yet either!

So, since this wasn’t a great question, I added one point to everyone’s score (whether you got it wrong or right). I think this is the most fair way to handle these types of questions because it doesn’t penalize anyone: if you got the question wrong, you get that point back, and if you got it right, you get an extra point.

Let me know if you have any questions. Also, if you’d like to come take a look at your exam at any time, just let me know and we’ll set up a time.