Tools for the Toolbox: _. . ._. …_ . …

In honor of the fact that I’m rotating through Neurology at the moment, I’m proud to present…

NERVES!

(In case you don’t read Morse Code and were too lazy to google it, that’s what the title says.)

So, nerves are super-cool.

Here’s a picture of one, so you can join me in basking in the coolness of nerves.

Are you basking?

What’d I tell you? Coolness personified.

Well, maybe not personified….but if you squint closely, you may find yourself glancing at your neighbor and having a shift in perception, suddenly seeing his shape described only by a network of white, filamentous strands, as if he were a sculpture of spiderwebs….

Only me?

Darn.

Well, that’s okay. I also subconsciously judge people based on how easily I could start an IV in the veins on their hands.

(The study of medicine engenders its own special flavors of crazy.)

Anyhoo. NERVES!

A nerve cell is called a neuron. That’s the cell in whose coolness we were basking, up there a minute ago.

The job of a neuron is to pass information along, in the form of an electrical signal. (The way this happens is super-cool, and warrants its own post, so stay tuned. For right now, we’ll just talk about how they’re arranged.)

There are three parts to any neuron.

The dendrites (from “dendron”, which means “tree”) are the tree-branch-like projections off of the central cell body, also known as the soma or perikaryon. The dendrites collect impulses from surrounding neurons and send them to the perikaryon. There are usually a lot of dendrites on a neuron, making it easier to collect a LOT of information.

(Dendrites are probably the coolest things in the human body, because they like to rearrange themselves like crazy, making a dynamic structure that allows us to learn and remember things, and adapt to changes and all kinds of other important things like that.)

So, a neuron receives signals through its dendrites. But what if it wants to say something to the other nerves in the area? That’s where the third part of a neuron comes in, the axon.

Axons are incredibly cool structures, too! There’s a conical process on one end of a perikaryon called the axon hillock, and that’s the staging platform that shoots off the axon, a long, cylindrical filament that keeps its diameter for practically its entire length (whereas the dendrites tend to taper off). Axons are responsible for carrying information away from the perikaryon, toward whatever it’s supposed to connect with and talk to. Wherever it is.

(Think about how far away the tip of your toe is away from the end of your spinal cord [it’s a little above the level of your iliac crests, if you remember from this post. ] A nerve axon has to run that entire distance to carry its signals! They’re LONG, man!)

Okay, a little more terminology, then I’m calling this post a wrap and going to bed. And then we’ll get to the REALLY incredibly cool stuff in the next couple of posts.

The connection where nerves can talk to each other (or to muscles or gland cells or whatever) is called a synapse. Axons can form synapses with cell bodies, dendrites, or even other axons. For clarity purposes when describing nerve connections, a neuron sending a signal toward the synapse is called “presynaptic”, and a neuron that receives the signal from the synapse is called “postsynaptic”.

Makes sense, right?

Synapses are oases of awesome in a desert where the sand is made of unabashed coolness. They might get their own post. Or a couple. We’ll see.

Anyhoo. NERVES!

Axons are covered with a nifty stretch of jointed insulation, called a myelin sheath. More about that, too. Later.

I know you can’t wait. I hardly can either.

But I’m pushing bedtime as it is.

Man, I’m a geezer already.

But that’s okay. At least you can read this at three in the morning, if you want.

Because your nerves make it possible.

NERVES!!!

Pictures:

Resources:

Junqueira, Luis Carlos; Carneiro, Jose. Basic Histology: text and atlas. 11th edition. McGraw-Hill, 2005.

The contents of this site, such as text, graphics, images, and other material contained on the Site (“Content”) are for informational purposes only. The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this Site!

If you think you may have a medical emergency, call your doctor or 911 immediately. This blog does not recommend or endorse any specific tests, physicians, products, procedures, opinions, or other information that may be mentioned on the Site. Reliance on any information provided by this blog, or other visitors to the Site is solely at your own risk.

The Site may contain health- or medical-related materials that are sexually explicit. If you find these materials offensive, you may not want to use our Site. The Site and the Content are provided on an “as is” basis.

If you use this as if it were real medical information, I’ll bask in the cool awesomeness all by myself. Didja hear me? ALL BY MYSELF! (So there.)

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Published in: on October 14, 2010 at 1:40 am  Comments (5)  
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How To Talk Doctor! Lesson 5.

Lesson 5: “-oma”.

-oma = “Tumor” or “swelling”.

Though this is not a perfect rule, when you hear “-oma” on the end of a word, it usually suggests cancer of some sort.

Used alone with a prefix that designates a tissue type, “-oma” classically has a connotation that suggests a benign tumor rather than a malignant one. (Ex: adenoma = benign tumor of a glandular epithelial cell type; chondroma = benign tumor composed of cartilage.) That’s not always true, though. So don’t depend on it.

Let’s try it!

“-oma”-words that have to do with tumors:

Carcinoma – This is a general term for a neoplasia (neo = new; plasm = growth) that originates from an epithelial cell type. (The body is made of four main cell types: epithelial, connective, muscle, and nerve.)

Epithelial cells cover things, secrete things, and transport things from one side of a membrane to another. Epithelial cells constitute the skin, the linings of the mucous membranes, glands, the lining of the bladder, and the linings of various ducts and tubes within the body.

After age 45, more than 90% of all tumors are derived from cells of epithelial origin.

The Culprits.

Lymphoma – Classically used to describe neoplasias of white blood cells (immune cells) that tend to stay in discrete masses. (There’s some overlap with “leukemias”, which are neoplasias of white blood cells that classically involve the bone marrow and often present with tumor cells in the blood.)

This is what a “mantle cell lymphoma” looks like under a microscope. I saw a patient with this type of lymphoma just last week.

Lipoma – A benign tumor composed of fat cells. (Lipos = fat)

There are also malignant tumors composed of fat cells, known as liposarcomas. My first-ever surgery as a third-year medical student was actually a liposarcoma removal. The thing was beach-ball-sized. And guess who got to hold it out of the way as the surgeons removed its connections to the patient’s abdomen? That’s right! My first surgery experience consisted in standing with my arms completely wrapped around a heavy, gigantoid tumor made of fat cells. For at least four hours.

It looked a little like this:

Have you hugged your liposarcoma today?

Incidentaloma – This is a tumor (or other finding) found by coincidence on an imaging study that was actually looking for something else entirely. These can be benign or life-threatening, and are often completely asymptomatic (a = without; symptomatic =….well, you got it).

This was an MRI study of the lumbar spine (the stack of rectangular objects in the middle). This patient also has 'arrow sign': the radiologists are drawing attention to a mass around the distribution of the left adrenal gland. Surprise!

“-oma”-words that don’t necessarily have to do with tumor (except maybe in the Latin sense of the word):

Glaucoma – This is a group of eye diseases characterized by certain changes in the visual field and the cup of the optic nerve. Often associated with high pressure inside the eye.

This is what a doc is looking at when they shine a bright light into your eye. This is what the back inside surface of the eye is supposed to look like.

This is glaucoma. Notice that the optic nerve (the circle in the middle) looks like a cup; the indentation in the middle is far bigger than it’s supposed to be.

Stoma – This is an opening in the body that may resemble a mouth. Sometimes refers to a hole made in the body and maintained to allow drainage.

Stoma

MOMA – This is a museum in New York.

It’s pretty swell, but I don’t think that counts.

Now go forth and understand some doctor-talk!

References:

Robbins and Cotran. Pathologic Basis of Disease. 7th edition. Elsevier, 2005.

Junqueira, Luis Carlos; Carneiro, Jose. Basic Histology: text and atlas. 11th edition. McGraw-Hill, 2005.

Pictures:

http://images.google.com/imgres?imgurl=http://www.radsource.us/_images/0509_6.jpg&imgrefurl=http://www.radsource.us/clinic/0905&usg=__LICH_TJrQI4iKkKmn_jpCsjFjpA=&h=266&w=350&sz=41&hl=en&start=10&itbs=1&tbnid=rvMhgF5JntpO4M:&tbnh=91&tbnw=120&prev=/images%3Fq%3Dincidentaloma%26hl%3Den%26sa%3DN%26gbv%3D2%26ndsp%3D18%26tbs%3Disch:1

The contents of this site, such as text, graphics, images, and other material contained on the Site (“Content”) are for informational purposes only. The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this Site!

If you think you may have a medical emergency, call your doctor or 911 immediately. This blog does not recommend or endorse any specific tests, physicians, products, procedures, opinions, or other information that may be mentioned on the Site. Reliance on any information provided by this blog, or other visitors to the Site is solely at your own risk.

The Site may contain health- or medical-related materials that are sexually explicit. If you find these materials offensive, you may not want to use our Site. The Site and the Content are provided on an “as is” basis.

If you use this as if it were real medical information, I will come to your home and hug your beach-ball for at least four hours. It will almost certainly confuse your children.

Published in: on March 30, 2010 at 12:51 am  Comments (2)  
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How To Talk Doctor! Lesson 1.

Let’s warm up with the Amateur Transplants! (Warning: contains generally-frowned-upon four-letter words. Probably not safe for work, at least for those four seconds.)

Okay, class. Settle down now. Timmy, I saw that. Open your books to page “-itis”, and we’ll begin.

Lesson 1: -itis

-itis = inflammation.

“Inflammation” is a condition that is characterized by
-Rubor (redness)
-Calor (heat)
-Tumor (swelling)
-Dolor (pain)
-Functio laesa (loss of function)

It’s the body’s normal response to a threat: bacterial infection, a splinter in your finger, etc. Certain tissues might get inflamed as a result of an autoimmune process, in which the body attacks itself.

Put the “-itis” suffix after any body part or organ to mean “inflammation of the ________”. For maximum obscurity, use the fancy doctor-word for the body part or organ.

Let’s try it!

Pancreatitis = inflammation of the pancreas

Dactylitis = inflammation of a digit (finger or toe)

Hepatitis = inflammation of the liver (hepatic = liver)

Myocarditis = inflammation of the heart muscle (myo = muscle, card = heart)

Senioritis = inflammation of the senior

Blogitis = inflammation of the comment thread in a controversial blog post.

Thank you for your attention; class dismissed.

Pictures:

The contents of this site, such as text, graphics, images, and other material contained on the Site (“Content”) are for informational purposes only. The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this Site!

If you think you may have a medical emergency, call your doctor or 911 immediately. This blog does not recommend or endorse any specific tests, physicians, products, procedures, opinions, or other information that may be mentioned on the Site. Reliance on any information provided by this blog, or other visitors to the Site is solely at your own risk.

The Site may contain health- or medical-related materials that are sexually explicit. If you find these materials offensive, you may not want to use our Site. The Site and the Content are provided on an “as is” basis.

If you use this as if it were real medical information, I’ll digitally palpate your external obliques for the purpose of initiating repeated contraction of your thoracic diaphragm, in turn causing the emission of multiple monosyllabic vocalizations, and possibly triggering involuntary micturation.

Published in: on February 13, 2010 at 6:46 pm  Comments (3)  
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