Physiology with Liz… Episode 2: All-Purpose Muscles And Knee Replacement Infections

Intro to Psych started my obsession with the human brain.

A&P started my obsession with bones and muscles.

And nursing has started my obsession with the respiratory system. Breathing is so cool, guys. You don’t even know. Our body so finely regulates every level of everything we need to live via so many mechanisms across so many systems. Changes are subtle and swift and that’s how we stay alive. I love homeostasis.

Little things make me happy. Like the fact that it’s harder to do exercises that have a lot of arm raising movements because your accessory muscles for ventilation are used to stabilize your arms and shoulders. Multi-purpose muscles! Muscles that help you breathe AND help support your skeletal system depending on the situation? Awesome. It’s like having a substitute teacher to flexibly cover deficits wherever/whenever they’re needed. Like “Hey, breathing muscles, need some help? Let’s be super efficient together” then later “Hey, arms. I see you’re doing some intense activity over there. Don’t worry, I got your back. Although the breathing muscles are gonna have a little tougher time of it now.” Our bodies are staggeringly functional in such a minimalistic way.

Sometimes muscles are multi-purpose to the point of difficult classification. From Wiki:

There is some controversy as to which muscles may be considered accessory muscles of inspiration (Kendalll, McCreary, Provance, Rodgers, Romani, 2005). The sternocleidomastoid (elevated sternum) and the scalene muscles (anterior, middle and posterior scalene) are typically considered accessory muscles of breathing, however the following muscles have also been observed contributing to the breathing: serratus anterior, pectoralis major & minor, upper trapezius, latissimus dorsi, erector spinae (thoracic), iliocostalis lumborum, quadratus lumborum, serratus posterior superior and inferior, levatores costarum, transversus thoracis, subclavius (Kendall et al., 2005).

On Thursday, I saw a real x-ray of a bone that was screwed together and it was so cool! The x-ray was right in front of me on the computer at the nurses station while the doctor was looking at it and I was in awe. It was so clear and beautiful.

And one of my classmates got to work with a patient who was recovering from a knee replacement and hearing about that was pretty neat.

Here’s a sad fact about knee replacements (and other types of replacements, too): If an infection develops for whatever reason at any time (post-surgery or later in life), a lot of times the limb has to be amputated because your body is less able to clear the infection via regular immune system means because you have replacement parts that aren’t natural human tissue. Essentially, the fake knee parts can’t mount a tissue immune response because it’s not actually real tissue. For example, there aren’t blood vessels in the fake parts because they doesn’t need perfusing because they’re not alive so the WBCs and everything that travel through the blood to fight the infection don’t really clear it the way it normally would be cleared.

I’m not explaining this well. Let’s try it another way. Basically when you have an infection, the whole tissue changes and responds to the infection so that the immune system can do it’s job. But because the fake parts aren’t really part of the body, the only way to clear the infection is from the surrounding tissues and that’s not as effective. It’s like the germs are sitting on a surface and the only way you can get to them is from the outside instead of from the outside AND inside and every other side like it would be if the original knee tissue was there.  I still don’t think I explained that well. But I hope you get the point.

Moving on…

I kind of wish I was a physical therapist sometimes. They are some of my favorite people in the hospital. Almost everyone on a med-surg floor needs some type of physical therapy. No matter how sick you are, you gotta move your muscles so they don’t atrophy. And even aside from that, just laying in bed all day is bad for many other reasons and can actually add to your list of illness-related problems and cause your health to further decline due to complications. The physical therapists modify each plan of action to fit the patient’s abilities and needs and it’s awesome to watch. They’re also super cheerleaders. So encouraging and great with the patients. They really connect with the patient and get so genuinely thrilled when the patient does extra well that day. Even when the patient doesn’t do well that day, they’re super pumped and positive and encouraging about what they were able to do. And they’re optimistic about how well the patient is gonna do the next day too. It’s just a very positive thing. I kind of love the idea of having a job where you constantly encourage people to do something that’s difficult but good for them. Because people are more likely to do a difficult thing if you’re very encouraging.

Even getting a person to be able to reach their knees or sit up on their own for 10 seconds is beautiful to me. And then you have the even more extreme cases where people recovering from a stroke and paralysis on one side of their body are able to walk again.


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