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.

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.

Just a quick update – Canvas should now be accessible to everyone! There was a setting that needed to be changed to allow student access – and that’s been fixed, so hopefully you can all get in and see your grades. If you are having trouble, please drop me an email.

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.

Here are some sample questions that are very similar to those on real exams (answers are at the bottom).

I hope this gives you a sense of how I write questions. All exam questions are multiple choice or matching (no short answer), and other than an EM image similar to the one below, there won’t be any images on the exam. However, I may ask you about what things look like (see question 10 below).

Also – I try to write really straightforward questions so that the exam actually tests what you know (rather than how well you can decipher my questions). So don’t overthink things and look for tricks or exceptions!

1. In general, what happens during the second phase of the embryonic period?
A. Cells proliferate and migrate
B. Internal and external structures begin to differentiate
C. Organs grow and mature
D. Organs reach their maximum size

Questions 2-5: Match each structure with the tissue from which it is derived. Each answer (A-D) should be used once, and only once.

A. Endoderm
B. Lateral plate mesoderm
C. Neural crest
D. Paraxial mesoderm

2. Bones of the head
3. Hematopoietic system
4. Lining of gastrointestinal tract
5. Muscles of the head

6. Which of the following is derived from the second pharyngeal arch?
A. Laryngeal cartilages
B. Meckel’s cartilage
C. Muscles of facial expression
D. Muscles of mastication
E. Stylopharyngeus muscle

7. Which type of intercellular junction attaches epithelial cells to the basal lamina?
A. Gap junction
B. Hemidesmosome
C. Macula adherens (spot desmosome)
D. Zonula adherens (belt desmosome)
E. Zonula occludens (tight junction)

Question 8 refers to the electron micrograph above, which shows a sarcomere in its relaxed state.

8. Which letter (and line) marks a region that contains ONLY myosin filaments?
A. A
B. B
C. C
D. D

9. On H & E staining, which type of connective tissue proper is composed of abundant ground substance, scattered cells, and some thin fibers?
A. Dense irregular connective tissue
B. Dense regular connective tissue
C. Loose areolar connective tissue
D. Loose reticular connective tissue

10. Which glial cell myelinates axons in the central nervous system?
A. Astrocyte
B. Ependymal cell
C. Microglial cell
D. Oligodendrocyte
E. Schwann cell

 

ANSWERS:
1. B
2. C
3. B
4. A
5. D
6. C
7. B
8. B
9. C
10. D

Nice job on the exam review Kahoot today!! Way to go RL!!

I posted today’s Kahoot on our Kahoots page if you want to go through it again.

I posted a new crossword on connective tissue, cartilage, and bone on our crosswords page!