Bones!

We've had a rough week. Last Thursday, J decided to grab the inside of a restroom door as it was being shut, breaking the tip of his finger and turning his finger nail completely black almost immediately. The doctors say it should be back to normal in the next four weeks. Though it's sad to see my child in pain, this incidence got me thinking about how much I love learning about the body and how it continues to motivate me in my current research.

The human body amazes me! And, guess what? We're still learning about us! Research is awesome.

Do you know how many bones are in our body? 206, at least for adults. Babies are born with more, but they end up getting fused/grow together as they age. One of the reasons babies have more bones is to make them more squishable to help with the birthing process.

Did you know that astronauts lose bone when they are in space? The same goes for people who are bed-ridden for lengthy amounts of time. Bone is this amazing material that responds to load/weight/forces that you apply to it. If you don't use it, you lose it! Fun studies have shown that the opposite is also true. Tennis players tend to have thicker forearm bones in their dominant arm when compared to the other arm.

More research: One of my favorite grad school classes, Orthopaedic Bioengineering, was taught by Dr. Dennis Carter. He co-authored Skeletal Function and Form: Mechanobiology of Skeletal Development, Aging, and Regeneration (affiliate link) with Dr. Gary Beaupre. Both gentlemen have spent their research careers studying the formation and redevelopment of bones and other structural materials in our bodies and have shared the information they've learned with us through this book.


Since we've been preoccupied with J's finger and getting ready for Baby Sister (who will be here in six short weeks), I thought it would be a good time to do the Magic School Bus kit on the Body and Bones, but we've already done the age appropriate experiments in some form or another. Here's a flashback to some of the fun with the human body we've had:

• How muscles work to move a joint: elbow model.
• Model lungs in a soda bottle.
• Different forces when popping packaging bubbles.
• A visit to the gait lab: analyzing human motion.

Impulse and packaging bubbles

J loves popping all of our packaging bubbles (luckily for him, we do a lot of online shopping). He has experimented with the most efficient and satisfying way to pop the bubbles. One day, I decided to record his tactics:

He figured out that popping works best with a quick jump on the bubble, but he had a hard time popping the bubbles with his hands? Why?

With jumping:
1. He gets all of his weight (and then some - biomechanics, yay!) on the bubble.
2. The time he exerts the force is short.

With his hands:
1. Not all of his weight is transferred to the bubble (ie, he's not doing a handstand on it). Some of his weight remains on the ground while his legs hold him up.
2. The time he exerts the force is a lot longer when he uses his hands (the bubble takes time to deforms before it pops).

What simple science experiments have you done this week?

BioX Kids Day 2013 - Elbows revisited

I was asked to help with Stanford BioX's Kids Day this year, which happened today!

I met lots of fun families. Thanks to all who stopped by to learn about how your arm works!

Here are some old posts for your reference if your elbow breaks (ouch!) or if you want to do it all by yourself. It's very easy and a wonderful way to learn how muscles move the bones in your body.

Elbow Booth Recap, BioX Kids Day 2012.

Elbow Lesson for High Schoolers (with a little kid adaptation).

Science Saturday Elbow Lesson (intro with moving a rock towards me by pushing on a string).

I love learning about how my body works. I hope you did too.

J visits the gait lab

My poor baby, J, was sick for his fourth birthday last week. It started the day before his bday party and lasted through the weekend until Wednesday of last week. Wednesday, he was still banned from school but feeling good enough to be compliant while I got some work done at the office. For fun, I thought I'd show him what I do.

I manage a motion capture laboratory where we use special cameras to analyze the forces and moments on knees through gait analysis. Gait is a fancy term for walking. Ultimately, we want to find out where knee osteoarthritis starts before symptoms appear in order to develop interventions to slow or even prevent the progression of osteoarthritis (the degeneration of the cartilage - that slippery material that helps your knee move without friction/creaking). Currently, osteoarthritis is diagnosed once you feel pain, and you can only treat the symptoms.

Well, my little guy doesn't know the particulars of my job except that I have access to some cool science equipment. We decided to do a quick collection with J. We stuck reflective markers on our subject. The markers are plastic balls covered in reflective material, like what's on running shoes. The special cameras then send out infrared light to detect the x, y, z position of each marker during each frame of the collection period (typically 120 capture points/second - aka 120 Hz sampling rate). We have force plates (sensors) embedded in the floor too.

J with the motion capture markers

J insisted on the forehead marker

Then instead of walking, I had him dance around. Here's what was reconstructed in the computer (looped twice). The red arrow is the force J is exerting on the floor.

John just showed it to him for the first time, and J was able to point out his feet, legs, and arms. He loved it.

Then just a fun picture of J and the floor plunger (technical term "floor panel lifter"). It's just not working:

I actually got work done too! Win win!

Why do we have brains?

This was the first question from my 3 year old this morning. My immediate answer (while I was getting ready for work) was, “Our brains help us do everything we want to do. Without your brain you wouldn’t be able to move, eat, speak, think, and lots more.” I of course then said, "We need to do all we can to protect our brains, so we can continue to move eat, speak, and think. If we injure our brains, we won't be able to do the things we want to do." In other words, I think helmet wearing is super important. J responded, "We wear helmets to protect our brains!"

Thinking about it from a biomedical engineering prospective (older kids/adults), our brains are the most amazing command center controlling our bodies! As we grow and learn, connections from one part of your brain to another are formed. Sometimes connections are easier than others (ie, when you are young, you can learn a foreign language better). Regions of the brains are responsible for different things, so if you injure specific regions of your brain, you might lose different abilities to do things.

On a personal note, I was 25 yrs old and experiencing some pretty persistent, bad migraines that were giving me "mass effects" like blurred vision and numbness. I was diagnosed with a defect called arteriovenus malformation (AVM) in my brain. It's where the veins and the arteries are directly connected, basically a useless vein since the oxygenated blood doesn't go through the capillaries to my tissues, just straight to the vein and back to my heart. Part of the problem is that the arteries are a high pressure system and veins are low pressure. The high to low pressure switch can cause eddies (turbulent flow), which can lead to the formation of aneurysms (where the artery wall balloons out) and bleeds. Talk about a scary diagnosis! Luckily (if there's something to be lucky about), it's a birth defect (so I've lived peacefully with it for a long time), it's gigantic and "diffuse" (5x5x5 cm), and I have inherently low blood pressure.

Here's a picture. You can see the AVM in both views here (look for asymmetry and squiggly lines). The AVM is in my left frontal and parietal lobes of my brain. 5x5x5 cm is a pretty large portion of the brain, and I've been declared neurologically normal, which to me is amazing proof of the adaptability of the human brain (and cardiovascular system too)...

Despite its quirkiness, I love my brain.

**Edited on 1/12/13 to add:
AVMs can be found anywhere in your body. AVMs in the brain are particularly scary since a problem there can lead to a very big problem. I think they are more common than we know. Many people live their lives with AVMs and don't even know they have it. I could have treatments to get rid of the AVM, but the risks of treatment outweigh the benefits since I do not have aneurysms.

Science Saturday in the Park: Elbows and Muscles

Wow, we had quite a turn out this Saturday to learn about elbows and muscles.  Thanks everyone for coming!

I repeated the Elbows and Muscles lesson I did at Kid's Day since I had leftover material (and it's a fun one!).  The detailed instructions on how to make the elbows are here: younger kids elbow lesson, while the more advanced lesson can be found here: middle+high school elbow lesson.

Since the science days are attended by neighbor hood preschool aged kids, I decided to add a new trick to help with conceptualizing how muscles really work.

I tied a string to a rock.

I then asked the kids to move the rock with the string (9 times out of 10 they intuitively pulled the string towards them).  I then asked them to push the rock to me using the string.  It never worked!  Strings don't push, they only pull.

Then if I still had their interest, we continued on to making elbow models (lessons described in the above links).  Some kids, depending on their interest level, got anatomy lessons about the bones and muscle names (major muscles: biceps (flexion/bending), triceps (extension/straightening); arm bones: humerus (upper arm), radius and ulna (lower arm)).  We also brought up tendons, which attach muscles to bones (our string muscle was attached to our ruler bone with a paperclip "tendon").

One participant had an awesome question about making a punching motion.  Punching motions use more than one joint!  I discussed the way the shoulder moves (many, many degrees of freedom) that helps you raise your arm forward and pull it back, combined with the bending/straightening of the elbow (+rotational degree of freedom of the radio-ulnar joint) helps you punch.  To model this, you would need two more joints on top of the basic flexion/extension elbow we just made.  Your body has many muscles, bones, and joints that work together as a team to move you in the way you'd like to move.

P.S. To the parents: I don't endorse nor did I come up with the idea of the karate chopping elbows.  Sorry if your kids have figured out they can sock their sibling with the elbow model.

Link to bulk purchase of rulers: Charles Leonard Inc. Ruler, 12 Inch, Wood, 36 rulers

BioX Kids Day 2012 - Elbows Booth Recap

Holy Moly - I never thought I'd get around to this posting (I've been running nonstop since the event).

I had so much fun at Stanford BioX Kids Day 2012, on June 15th.

Here I am in my booth slightly before the event started.  They even gave me a super cool mad scientist shirt (which you can't really see, but trust me, it's awesome).

Anyways, that was the last time you'd be able to see me over the crowd.

It was so nice of the event coordinators to offer us ice cream (it sat on the corner as shown in the pic below for 2 hrs before I tasted the ice cream soup and threw it away).  I was explaining the elbow model to over 150 young kids over the course of 4 hours.

I had an awesome helper, Steve, shown behind me

Here's the original post for the elbow lesson I did, modified slightly to make it easily understood by younger kids: Biomedical Engineering Elbow Modeling (please note, that the idea for the project is in no way my idea see pg 16 of this lesson for where I found the idea).

How the lesson went (and increased in complexity depending on the age and interest level of the kids - which ranged from 2-18 yrs old):

• I asked to see the kids' elbows and then asked how many elbow each person has.
• I asked if they knew what muscles are and if they can show me their muscles on their arms
• I then tried to relate their muscle size to Popeye (and encouraged them to eat spinach), but apparently Popeye is pretty irrelevant nowadays.  Sad.
• I asked if they knew the names of the big muscle they were showing me (biceps).
• I asked if they could bend and straighten their elbows.
• I informed them that muscles only pull, which is a lot like what string does.  Have you ever tried to push something with a string?  It just doesn't work.  Period.
• So if the biceps are big when you bend your elbow, what muscle is big when your arm is straightened?  This is a hard question (luckily, I have pretty large triceps for people to poke - they aren't super big in most little kids).  You can also talk about how many heads each muscle has for the older kids (biceps = 2, triceps =3).
• Biceps bend the arm and triceps straighten the arm, all while pulling - if anything, this was a good take home message for the kids.
• Now that we established the ground rules (biceps bend, triceps straighten), we assembled our elbow model:
• Due to budget limitations, I went to the 2-ruler model - 1 ruler for the upper arm (humerus) and 1 ruler for the lower arm (radius+ulna).
• There were two big holes at the end of each ruler.  Don't use the bigger holes (unless you find bigger brads, but I unsuccessfully searched for bigger brads).
• The best holes to use for brad insertion were around the 2 inch mark.  Using a brad to connect 2 rulers made a simple hinge joint.  At this point, I demonstrated that it can open and close when I push on it.  Keep it open in an "L" shape.
• Our model is missing the most important piece of the lesson (ie. what bends and straightens the elbow?). I made a brief introduction to the term "tendon," pointing out that tendons connect muscles to bones.  If you want to see a tendon, look down toward your heels.  Your Achilles Tendon connects your calf muscles to your heels and is a very tangible example of a tendon.  We have smaller tendons in our arms connecting our biceps and triceps to our arm bones, but it's all inside our arm and we can't see it.
• To model a biceps muscle with a tendon, double knot a piece of string to a paperclip bent into a hook shape.
• Attach the tendon to the lower arm, around the 10.5" mark on the lower ruler, and string the string through the 10.5" mark on the upper ruler (don't tie it or knot it since you'll be pulling on it).
• Have the kids pull on the string.  Sweet, they just bent their elbow.
• For the older kids, ask them if they could point in the direction of the force the muscle is generating (along the line of the string).
• Now can they straighten their elbow?
• To model a triceps muscle (another string + paperclip hook) is a little more tricky since you want it to still attach to similar locations in the lower and upper arm, but the force is supposed to be directed downwards (opposite-ish of the biceps muscle).
• The trick here is making a joint capsule (lower friction environment) by directing the string through a paperclip which you stick on the back of one of the rulers.
• Attach the hook to the lower arm around the 9" mark.  Thread the string through the paperclip on the end of the ruler (the end closest to the brad), and then thread the string through the upper ruler around the 9" mark.
• At this point I want to point out that you should be holding your elbow horizontally, so gravity doesn't straighten your elbow instead of the triceps.
• While the elbow is bent, have the kids pull on the string that is threaded through the 9" mark on the upper arm (the "triceps").  It should straighten the elbow.  If it doesn't, check that the hook on the lower arm for that muscle is directed downwards.  Then check to make sure your string isn't getting caught up with friction somewhere else.

I made a lot of these for the little ones, older kids, 5+, can do it on their own

Super cool elbow makers:

I held while they pulled their muscles

Father and son, learning about elbows together. 

**Note the exact location of the holes may vary depending on what kind of ruler you purchased (ie. adjust 10.5" and 9" as you see fit).  Even my two purchases from the same vendor (a few months apart) varied. We used these rulers: Charles Leonard Inc. Ruler, 12 Inch, Wood, 36 rulers

Biomedical Engineering - Elbows and muscles

Last month, I was asked to lead the Biomedical Engineering workshop of a full-day event introducing engineering to 100 high school girls.  This was my third time leading the biomedical engineering workshop for the local chapter of the Society of Women Engineers.  I didn't want to repeat any lessons quite yet.  I have also been incredibly busy in my personal and professional life, so I hesitated leading.  I was hoping to mentor a younger biomedical engineer into leading a workshop (letting her take the ropes and lead with my guidance), but nobody stepped up as a lead.  Anyways, I decided to do something very easy in terms of preparation and conceptually.  Initially, I thought it might be too easy for high school girls, but it turned out perfect!

MUSCLES - we all have them, why not learn about them.

In particular, my lesson was about muscles for movement.

Time breakdown (total time 50 minutes):

• 7 minute presentation introducing biomedical engineering, giving a brief background of my job as a gait analyst (gait = fancy term for walking), the importance of modeling motion, and giving a very brief lesson on anatomy.
• Anatomy lesson included
• Naming how many bones in the body.
• Showing a picture/diagram the musculoskeletal system, highlighting some of the bigger, more well known muscles (quadriceps, biceps, triceps, etc.).  Muscles have an origin on one bone, cross a joint, and insert on a different bone.  Muscles work in tension only to move the body.  Different muscles move the body in different ways, so flexing is done by one set of muscles whereas extending is done by another set of muscles.
• Briefly describing ligaments and their function to connect bones to bones.
• Introducing tendons, which attach muscles to bones.
• Then we focused specifically on the arm with the elbow joint.
• 3 main bones: humerus, radius, ulna.
• For simplicity, we treated the elbow joint as a hinge.
• Flexor muscles: biceps, brachialis, brachioradialis, their attachment points, and their function(s).  Demonstrated that when I flex my arm, my biceps are activated, but when I release my biceps muscle, my arm doesn't flop down.  I need something to pull it back down.  That's where the extensors come in.
• Extensor muscles: triceps, anconeus, their attachment points, and their function(s).
• Introduced the challenge.
• 35-40 minute challenge exercise.
• 5-10 minute post-activity discussion.

The challenge was to make a model arm that could flex and extend.

I created this arm model worksheet for the girls to use/complete during the activity.  They worked in groups of 2.  Here's a run down with more specifics than the sheet provides (it was a big verbal instruction and feedback activity).

Easy set-up and materials

Materials:

• 3 rulers (one per arm bone) with small holes
• 1 large brad
• 3 paperclips
• 2 pieces of ~50 cm length string

Set-up for flexing the arm

Assembly:

• Place the three rulers one on top of each other and attach a brad through one of the holes on the end
• Pick a hole that the brad won't slide through.
• Open a paperclip, making a hook, and attach a string to the paperclip with a knot.
• Repeat for the second string and paper clip.
• Attach the paperclip (tendon) to the radius/ulna (lower part) of the arm and thread the string through the top most hole on the humerus (upper part).  Pull on the string from the top hole and watch the lower arm move up (flexing).

Flexing the arm

Activities:

• Play with origins and insertion points (put the string through different holes on both the upper and lower arm) and note how the lower arm reacts with different attachment points.
• Now that the arm is up (flexed), can you think of ways to extend it?
• I needed to give them some anatomical guidance/feedback here.
• Reminding them how the triceps are attached (behind the elbow).
• Reminding them that our joints are virtually frictionless (when they had decided to wrap the string around the brad or tightly around the back of the ruler).

Feedback:

• All girls were able to complete and understood the flexing of the arm.
• All girls could point to the direction the forces were pulling or needed to pull for flexion/extension (along the line of the string).
• 1/3 of the girls got the arm to successfully extend (they received a cool shopping bag donated by one of our sponsors).
• Redirecting forces was a tough concept for the girls.  The key to extension was to pull down but still have the muscle located "up" in the arm.  Many understood attaching the muscle from below, but when they attached it to the upper arm, the forces were still pointing upwards.
• This was something I had to think about on the fly and explain it to the girls in their individual groups as they were trying to solve the problem.  I tried to explain it in terms of a pulley system.  If I attach a string to a box, I can lift something directly up, right?  That's basically what the flexor muscle is doing.  But I can also pull down on something to lift it up if I have a pulley.  We need something that will pull the "arm" down when we pull up with the muscle.
• Methods for extension included making a pulley-like system, where force was redirected around the elbow:
• Attach a paperclip (why I suggested 3 paperclip) to the back of the ruler.
• Attach the brad to the little hole next to the big hole in the ruler and use the big hole as the pulley (they flipped the rulers opposite that the ones pictured in this blog).
• Holding the arm horizontally while flexing/extending works best.  That way gravity isn't extending the arm on its own.
• Attachment points: the bigger the muscle length, the easier movement was.  Think of it in terms of lever arms.  It's hard to lift 100 lbs straight up, but if you put it 4 ft away and create a fulcrum/lever system, I bet you can lift it fairly easily.
• This is a simplified version of an elbow.  How would someone change their model if they were going to account for rotation of the lower arm?  The key is that the elbow is actually two joints: the humeroulnar joint (what we modeled) is a hinge.  The radioulnar joint is the one that can rotate (pivot).
• The girls really enjoyed this lesson.  It was complex enough to get them thinking outside of the box but structured enough to where they didn't give up.

**This lesson was adapted from page 16 of these biomedical engineering activities.

Little kid adaptation:

J loved seeing the ruler arm go up and down, and kept asking about it.  I figured it's a good time to start the discussion about anatomy and movement.

It's easy to introduce muscles and that our muscles move our bodies:

• I can bend and straighten my elbows and knees thanks to muscles.
• Point out your bicep muscle.  Have your child touch it when you aren't flexing and then when you are flexing.  How does it feel different?
• See if your child can flex their own muscles.  
• When we exercise, our muscles get big and strong.
• If we are sick or injured, our muscles get weak.

We also talked about bones too.

• Our bones are hard and help us stand up.
• We need calcium for our bones to grow big and strong.  We can get calcium from milk, cheeses, and yogurt.
• We can break our bones if we're not careful.  If that happens, we'll be put in a cast, and we can't use that bone until it heals.

J liked playing with the strings and trying to move the rulers.  It could be fun if you have a marionette to show how different strings move different parts of the body.

Material note, we used these rulers: Charles Leonard Inc. Ruler, 12 Inch, Wood, 36 rulers

End of super long post, whew!

Related Posts:

• Muscles and strings - move a rock
• Bio-X Kids Day - elbows with younger kids

Model Lungs

I had too much fun that I couldn't share.  I was recently invited to speak to a group of Girl Scouts that meet once a month to have activities and discussions based around "technology."  The girls were well within the range of ages I've worked with before, but not of the blog target audience.***   However, I thought it would be useful for anyone who might be looking for a biomedical activity for late elementary-early middle school since there isn't too much info out there.

Background: I met the leader through work and told her about this blog and my mission (this blog is fun to write and share!).  I also told her that I've done an activity based off of this lung modeling activity with high schoolers, but I thought it would be easy enough for the age group.  She agreed.

The group of girls ranged from 8-12 years old.  I told them about wanting to be an engineer since playing with Lego Robots at age 8 and a little bit of my background - where I came from and went to school and that I'm a dancing mechanical engineer doing gait analysis.  I also told them about two modeling experiences I had.  No, not runway modeling.  I created a finite element (computer) model of a knee with a total knee replacement and made the knee walk.  I explained that the company could then exchange out different knee replacement designs and see how it would affect someone's walking.  I then told them about "bench modeling" and how I created a super simple, but effective, model through research.  I got to build the model and test it out for a super cool medical device company (and - I got to go to the slaughter house to pick up cow parts, even better!).  We talked about the importance of conducting modeling - main reason is safety, and the governing regulatory body - the Food and Drug Administration (FDA) that makes rules to keep people from being harmed.

I then talked about lungs.  We all have them.  Some of us even have a common problem, asthma.  We discussed basic anatomy of the lungs and a little bit about how asthma affects the lungs.  I introduced the materials they'd have to work with and gave them this handout that I made two years ago when I did it with the high schoolers.

Here's the basics (but check out the handout for a nice layout and some pictures)

Materials:

2 liter soda bottle with the bottom cut off

2 bendy drinking straws

3 small rubber bands

1 large rubber band

1 small produce bag

Clay

Cut off the bottom of a 2 liter bottom.  Attach balloons to the bendy part of the straws using a small rubber band, but be cautious not to make it too tight, as the airways would be closed and the model wouldn't work.  Tie the straws together with another small rubber band, again making sure that the straws weren't pinched closed.  Place the straws in the neck of the bottle and close off with modeling clay.  Take the produce bag (you might need to trim it down a little bit) and place it over the bottom of the bottle, attach with a larger/thicker rubber band.  Make your model breathe by pushing in and out on the produce bag (aka the diaphragm), making sure the bottle is air tight.  The "lungs" will fill with air, but don't expect them to be blown up like party balloons.  It might take a little adjusting of the bag and pulling on the bag to fill the lungs the first time, but then it should work well.  If it doesn't work, begin troubleshooting.  The airways are most likely clogged somewhere along the lines.  Note that I do not use binder clips, as I felt it was an unnecessary expense.  Using your fingers to pull the produce bag in and out for breathing works just fine.

Exhale

Inhale

Once the model is working, talk about what they can do to model asthma and other problems in the lungs.

Discussion:

All of them were able to get a working model, and most of them could model asthma (swollen airways).  The easiest way to model asthma was to squish the straw with a rubber band/the clay.  My favorites are those who use clay to clog up the straws .  Some of them were challenged to model what happens during pregnancy and why some ladies get short of breath easily (having to do with the baby in the way of the diaphragm).

The girls were very on top of their game that we ended the model making early.  I was asked to do an impromptu discussion at the end (instead of letting the girls roam free which would ultimately end in indoor soccer).  We talked about other lung problems, like cystic fibrosis, and how some people get double lung transplants.  We discussed what's going on during CPR.  We talked about smoking and tracheotomies (and that gross anti-smoking commercial of the smoker talking through the hole in her neck - Stages 2010).  The double lung transplant discussion led to a few other medical type questions and discussions (body rejection, relying on and being kept alive by machines waiting for donors).  The leaders even discussed organ donation, sweet!  Preaching it young.  So there's an array of great material to introduce to young kids just by making soda bottle lungs!

I felt good about volunteering.  I hope it inspired them to at least learn more about biomedical/mechanical engineering and/or the medical field.  The girls might even come to the gait lab next year to see what goes on there.  I can't wait.

***Note that my J tried to play with my model lung I created for the demo multiple times.  Once, he even brought it out to show his friends.  He totally was able to make it breathe, though I'm sure he couldn't explain what was going.  It was a neat toy with balloons and straws.