We’re Halfway There

My lecturer spent almost the entire lecture with his arm firmly wedged up the rectum of an invisible horse. He made eye contact with each student as his hand groped around the imaginary intestines, delivering lecture content as he went.

“Normally, you’re going to be able to feel the base of that caecum over on the right hand side. It should be soft, and we shouldn’t be feeling tight taenial bands.”

His waving fingers pointed straight ahead, “There’s going to be small intestine here, no taenial bands. But if there’s a strangulating lesion of the small intestine, these loops are going to distend like bicycle inner tubes. That’s not good.”

How his arm didn’t get exhausted after an hour spent horizontal, I don’t know. I did feel sorry for his imaginary patient though.

This man was a senior lecturer in equine medicine – and an excellent one at that. His focus was clinical relevance, and he was down to earth. But he could see it on our faces that the last time we’d tried a rectal, most of us failed to identify anything.

“Hey, this stuff is clinical, you’ll learn how to do it with practice. When I was a student, I rummaged around and couldn’t tell one thing from another. Sometimes experienced vets can’t find stuff either. That’s okay! I’m not expecting you to be able to do a rectal and go ‘ah yes, this horse has a nephrosplenic entrapment of his left dorsal colon’. You just need to know where things normally are at this stage.”

This lecture was part of the equine phase of our digestive system series. A series of lectures that felt like they would never end, that examined the anatomy, hormones, nervous control and physiology of the digestive systems of a whole range of species. For the two hours directly before this lecture, I’d walked around a room full of livers.

Before we’d studied livers, I’d seen them in dissections and wondered why they needed to be so big. What’s the point of taking up so much space? It doesn’t do a great deal.

Of course I’m now well-versed in the structure and functions of the liver. And I appreciate that it has a few more jobs than I initially thought. Memorisation of the liver functions is essential, but not all that easy. When it came to inventing a strategy, I settled on a rather pleasing mnemonic, which thanks to its bizzare imagery, has helped a few colleagues remember them too. You say liver, I say:

My Elephant Digs Potatoes Singing Very Raucous Blues

Which, obviously, pertains to metabolic processing of blood; excretion of drugs, hormones and waste; drug activation; plasma protein synthesis; storage of fats, vitamins and minerals; vitamin D activation; removal of bacteria and effete erythrocytes, and; bile acid secretion. One thing’s for sure: if a learning method sounds stupid, but it works… well then it ain’t stupid.

Livers are pretty damn amazing, and highly complex organs, but I won’t bore you, because you’d have gone to medical school if you wanted to listen to somebody harp on about them for 4 consecutive hours.

By the last Thursday of October, the digestive system module was finally over, and metabolism began. I knew this would mean a lot of chemistry and molecular biology. At the time of writing, I have actually written up the notes for the entire metabolism module, but I feel like I can’t remember any of it. Every time I try to recall something, the hundreds of chemical pathways all get knotted together in my mind. And not only are there enormous networks of pathways in an animal, each species has major differences that reflect their very different lifestyles.

For example, have you ever wondered how a herbivore survives with only roughage for a diet? Where will it get its protein from?

And what about obligate carnivores like cats? Where will they get their glucose from?

And how much difference does it make to your metabolism if you’re a meal-eating species as opposed to a continuous grazer? A hell of a lot.

But the Friday of that week saw a flashback to digestive system with a 3-hour lab entitled “In-Vitro Intestinal Motility”.

Having pretty much exhausted all our energy and motivation over the course of the week, group C trudged into the lab on Friday afternoon.

The aim of the lab was to observe the effects of different chemicals on the contractile activity of the gut. The research lab at Roslin had kindly provided us with the jejunum of two rabbits, and in groups of two we received a very short section of the gut in a little dish. Our first task was to use thread to suspend the one centimetre piece in a bath of Kreb’s solution. This solution mimics the temperature, salinity, pH and nutrient content of blood plasma in order to keep sections of organs alive outside the body.

Suturing thread to either end of the gut and trying to suspend it was an extremely delicate and frustrating task. In the end, I completed the setup for my pair, and did so much quicker than the rest of the class – hurrah! I’m obviously not the competitive type, though.

Here’s the setup for anyone remotely interested:

20161028_145653.jpg

The gut is tied at the bottom to a glass hook, and at the top to a device that measures force.

The whole thing is very tiny, which made setting up the gut tricky, especially given that any significant force on the gut would tear it and end the experiment.

After this, we started running a trace software, which recorded the force on a chart in real-time.

What was immediately apparent was that the gut was contracting rhythmically and exerting a small, pulsating force. These pulses are known as slow waves, and are generated by electrical activity within the gut wall, like the pacemaker of the heart.

After recording these slow waves for a while, we added a dose of acetylcholine to the bath. This is a neurotransmitter, and we got a modest response.

We washed this out, and then added nicotine, which is a smooth muscle stimulant. We very much upset our piece of gut:

Nicotine.png

But this was the response we expected. After washing it out again, we added noradrenaline, which is a neurostransmitter that you’re probably familiar with. This is what it did:Noradrenaline.png

“Claire, I think we killed our gut.”

We left the trace running, but the slow waves never returned. The little piece of jejunum sat completely still in the bath. But we knew what needed to be done. So we added acetylcholine to stimulate things to get going again:

Acetylcholine 2.png

Yes, we have a pulse! After an initial post-resus panic, the gut calmed down and settled back into its slow waves. Champion.

What else can we do to it? Aha, atropine. That should finish it off for good. Measuring out a significant dose of atropine for such a tiny section of tissue, we waited to see what would happen. We didn’t have to wait very long:

Atropine.png

Yep, that’s done it good. The first vertical black line marks administration of the atropine, which took hold pretty darn quickly. After a minute and a half waiting for a sign of life, we tried to use acetylcholine at the second black line to revive the gut. No cigar.

Another couple of minutes passed, and we’d moved on to writing answers onto our report sheets. I just happened to have another look at the trace.

“Hey, Claire, look at that!”

Atropine 2.png

This little gut just did not want to die.

We spent the next while playing with different drugs to watch their combined effects, but eventually we overdosed it so heavily with noradrenaline that we couldn’t get it back. Oh, well.

The lab was ultimately a fun experiment that actually made me use my brain to understand the different responses we observed. We don’t do labs very often, and it’s not an experiment I will ever run again in my life, because the intestines I see will (hopefully) be inside a patient. But by the end of the session, I felt like our little gut had been through a lot with us, and I’d almost got emotionally attached to the little fighter. But it was a Friday afternoon, and it was a 3-hour lab, and I really just wanted to go home.

Because at home, my folks would be waiting for me. I’d barely skidded through my flat door, and I was tearing about the place trying to pack an overnight bag. I then scuttled out the door and down the stairs. I was only halfway down when I saw the bunch of them standing on the stairs, on their way up. I did wonder for a second how they’d got through the keycard-operated doors, but I didn’t care. It was so good to see them.

After a bit of crying and a lot of hugging, we caught up over an Italian on the beautiful George IV bridge, which is a stunning World Heritage site.

On Saturday morning, we all trooped off to see Edinburgh Castle. It’s funny how you can live in a place for so long and not see its most outstanding parts. I was more than a little miffed about the lack of student discount, but the castle itself is absolutely stunning. Totally different to what I’d expected, it’s actually a collection of lots of separate buildings. This means a lot of walking around outside, and somehow the weather held out for us!

The history is extensive and fraught with conflict and plotting, and I walked around all day with images of Braveheart charging about in my head. The one o’clock gun is very loud, and I find it strange that I’ve never heard it when I’ve been in new town.

20161029_132922.jpg

20161029_162907.jpg

On Sunday, we headed to the National Museum of Scotland. This is where we went when they came up last October, and we’d seen the natural history gallery.

This time, we explored the Science & Technology gallery. Thomas had a go at driving an F1 car, and you’ll never guess who I bumped into!

20161030_124437.jpg

The last time I’d seen Dolly, I was a bright-eyed fresher exploring the university’s main library. Since then, she’s been moved into the National Museum where there’s an exhibition on genetic technology. Suffice to say that after a semester last year learning the ins and outs of genetic science from world-experts, I was happy enough just to say hi to my woolly friend and move onto another topic!

Saying goodbye yet again was really difficult. But I knew that this visit marked the halfway point for what is the longest semester of the year, a semester that’s longer than that which almost any other British student must go through.

That brings us to October’s end, and I’ll leave you with the masterpiece Rowena and I created in celebration. Thanks for reading, and stay tuned to find out what’s happened this November!

20161031_231752.jpg

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s