We’re going to be talking about a LOT of diseases in this course – everything from mild skin infections to deadly brain cancers – and each disease has its own unique features that you’ll need to learn and remember.
This is a lot of information.
If no one helps you organize all of this information, then all you can do is plow through it and try to memorize as much as possible. That becomes frustrating very quickly. Plus, it’s a crappy method for retaining information. Your brain only holds that type of stuff in short-term memory until exam day – after that, it’s gone.
In this course, we’ll take a different approach. We’ll limit brute force memorization to an absolute minimum, and focus more on understanding why things are the way they are. And because your brain is constantly searching for patterns and similarities, we’ll give it the structures and frameworks it wants, so it can relax and enjoy itself.
Here’s a blueprint.
Here’s the first structure we’ll give your brain – it’s a list of the four aspects we look for in every disease:
- Etiology: the cause of the disease.
- Pathogenesis: the underlying mechanism of the disease.
- Morphology: the tissue abnormalities you see in the disease.
- Clinical manifestations: the signs and symptoms of the disease.
You can use this as a blueprint for any disease, and it will help you keep all the information in a pattern that your brain can remember. Let’s see what it looks like for a few of the diseases in our first lectures.
- Etiology: numerous factors including hyperlipidemia, hypertension, smoking, genetics.
- Pathogenesis: chronic endothelial injury makes the endothelium more permeable; macrophages and lipids accumulate, smooth muscle cells proliferate and lay down collagen, and you end up with a plaque in the wall of the vessel. Plaques can occlude the vessel, or sometimes a thrombus will form on top of a plaque, filling up and occluding the vessel.
- Morphology: vessel walls show plaques consisting of a soft fatty core covered by a fibrous cap.
- Clinical manifestations: range from nothing (if the plaque is small) to chest pain, shortness of breath, and death (if the plaque blocks a major artery feeding the heart).
- Etiology: unknown
- Pathogenesis: unclear – but probably related to a decreased ability to excrete sodium, which would lead to high levels of sodium in the blood, which would pull water into the blood because osmosis – and then you have a high blood volume etc. etc. and high blood pressure.
- Morphology: hyaline and hyperplastic arteriolosclerosis
- Clinical manifestations: nothing, until you’ve had it for a while, then it can damage your vessels and lead to stroke, aortic dissection, etc.
Abdominal Aortic Aneurysm
- Etiology: atherosclerosis, sometimes genetic defects
- Pathogenesis: plaques damage the wall of the aorta, leading to bulging of the vessel.
- Morphology: enlargement of the aorta below the renal arteries; lots of atherosclerotic plaques in the vessel wall.
- Clinical manifestations: can rupture, leading to massive blood loss. High mortality rate.
- Etiology: either a drug or a bug
- Pathogenesis: possibly a type III hypersensitivity reaction (remember what that one is?)
- Morphology: necrotizing vasculitis in small vessels
- Clinical manifestations: depends on the location of the affected vessels (we didn’t talk about this in class)
Make sense? Let me know what you think!