Vitals & Bits #15: The Reticular Formation
Everyone has a dark secret, biologically speaking. Perhaps it’s a mole shaped like Fozzie Bear. Maybe a habitual after-dinner fart marathon. Could be bad breath, or slow sperm, or toe hair.
Even the Adonis-like Dr. Muscles eventually developed a biological glitch. His arrived suddenly one night, in the form of unremitting, head-crushing, intensely sonorous snoring. I’d lie awake next to him, pillow over my head and hands clasped over my ears, quietly emitting an unbroken stream of profanity so foul and hateful that you’d think I was being tortured within inches of my life, rather than just being kept awake by my boyfriend’s snoring. Clearly, sleep deprivation doth make monsters of us all.
One night, a month or so into Dr. Muscles’ nightly snorathon, I found my mind wandering as I listened to his billion-decibel honking. I started to think about a book I had been reading that day, and I began picturing myself as one of the characters in the book. Soon my mind descended into that dim, loose-association cognitive limbo that happens just before sleep. The next thing I remember, I woke up the following morning, well-rested and feeling like the star athlete on a box of Wheaties cereal.
So how did I manage to fall asleep amidst the nocturnal music of Dr. Muscles’ obstructed upper airway? My reticular formation, or a part of the brainstem that acts like a gatekeeper for all kinds of incoming sensory data, can take the credit. The reticular formation is responsible for a variety of functions, from helping to maintain balance and resting muscle tone, to helping the brain integrate sensory data with motor coordination. Part of the reticular formation’s job is to determine which sensory data is allowed to reach the conscious part of the brain. Luckily for me, the reticular formation can learn to ignore repetitive, meaningless stimuli, such as the sound of someone snoring. This allows the brain to quickly process and react to new or unusual stimuli, like a smoke alarm.
Though my reticular formation learned to ignore the sound of Dr. Muscles’ snoring, it never learned to ignore the hundreds of other handsome men prowling around the hospital, with their beepers constantly chirping inside the pocket of some gracefully crumbled lab coat or some overly laundered pair of scrubs. Oh, hospital land. With so much to enjoy, who needs a boyfriend or sleep anyways?
Vitals & Bits #14: The Fibula
So, in the spirit of full disclosure, I’ll tell you right off the bat that the fibula isn’t exactly the most riveting body part. It’s pretty much just your average bone. And as fascinating as bone tissue is, there isn’t anything especially unique to the fibula itself that makes it any more or less fascinating that other bones. But, like people, not all body parts are destined to capture the imagination and adoration of the public. As such, I think it’s worthwhile to focus on the supporting players rather than the anatomical hotshots (like that damned fancy liver) every now and again.
The fibula is one of two long bones in your lower leg that connects the ankle area to knee area. It’s kind of a sidekick to the tibia, which is the larger of the two bones. You can feel your tibia on the front of your lower leg, in the area also known as the shin. The fibula runs parallel and just lateral to the tibia. (In anatomy, the term “lateral” means “moving away from the midline of the body”, i.e. the eye is lateral to the nose, the ear is lateral to the eye, etc. So the fibula is to the right of the tibia in the right leg, and to the left of the tibia in the left leg.) It’s covered by muscle and tissue, so it can’t be felt as easily as the tibia.
Like the tibia, the fibula is involved in the ankle joint and connects to the other bones of the ankle via ligaments. The bony bump you feel on the outside of your ankle, called the lateral malleolus, is the lower end of the fibula.
Unlike the tibia, the fibula is not directly involved in the knee joint.
This means that many injuries to the fibula occur at the level of the ankle. In fact, the majority of ankle fractures in older women involve the fibula.
Whether you’re young or old, male or female, Team Edward or Team Jacob, having a broken bone sucks. A broken ankle is particularly distressing, given that the whole walking and standing and weight-bearing nonsense we normally take for granted becomes extremely painful, if not impossible, for quite a long time. And “a long time” is no exaggeration: bones take forever to heal! This is because they don’t receive very much blood supply. Blood flow is crucial for delivering the nutrients that the body needs to heal itself, and although blood vessels snake in and out of your bones like ivy through a terrace, there just simply aren’t enough of them to make healing an efficient process. This is why bones require immobilization and activity restriction for a prolonged period of time to heal. Anyone who has been in a cast and crutches for six weeks knows how slowly those weeks crawl by.
Because of this, I hereby designate this day as “Help Out Someone with a Broken Ankle” Day. President Obama’s actually considering making this a federal holiday, in which our nation collectively commemorates important broken ankles throughout American history. So, though you probably rarely think about it, take a moment to lavish some attention on your fibula. Touch the bony lateral malleolus, hop on one foot, kick someone you dislike, and savor the feeling of an intact ankle. Coo to your legs about how they’re absolutely fibulous. Then march yourself over to the house of someone with a broken ankle and help them do laundry or make them breakfast or something. It’s OK to tease them about how they broke their ankle while guzzling Jim Beam and trolling around Central in a pair of stiletto heels. So long as you make their life a little easier, you’ll be making America proud.
U.S. approves a new emergency contraceptive named after your friend
Weirdly, it's called Ella. Probably because that's catchier than ulipristal acetate.
The drug works for five days after unprotected sex. Plan B, the emergency contraceptive on the market today, only works for three days. Europeans have had Ella for a while. In the U.S., it will be prescription only.
Vitals and Bits #12: The Myelin Sheath
Most neurons (or nerve cells in the brain, spinal cord, and peripheral nervous system) are shaped kinda like a sunflower. In general, neurons have a cell body (the center of the sunflower), projections off the cell body called dendrites (the petals of the sunflower), and one long tail called the axon (or the sunflower’s stem). In order to “talk” to one another, nerve cells pass electrical impulses down their axons and spread the impulse to the dendrites of other nerve cells.
Some nerve axons can be incredibly long. The longest axons in the human body are over a meter in length. Wow! And as we all know, size matters when it comes to neural excitation. The nervous system depends on lightning fast communication to function properly, and we can’t have electrical impulses puttering along limp axons. So in order spread electrical signals quickly, nerve cells have a special insulating substance covering their axons. This insulating substance, known as myelin, is a fatty material that coats the axon and keeps the electrical impulse from dissipating. The coating of myelin around the axon is called the myelin sheath. If it helps you to think of myelin as an electrical lubricant, be my guest.
Myelin is white in color, thus imparting the characteristic color (or lack thereof) to the brain’s white matter. White matter can be found on the interior of the brain, and comprises trillions of myelinated axons linking all the various parts of the brain.
Myelin is made by a special type of neural support cell called a glial cell. Glial cells and neurons are like BFFs. Glial cells are the Paul Rudd to the neuron’s Jason Segal. They’re the Nicole Richie to the neuron’s Paris Hilton. Like Harold and Maude, or Fred and Ginger, or King Arthur and Sir Lancelot they are. Do you like how my pop culture references just get more and more outdated? Shut up. I’m in grad school. I have no time to keep up with the latest Bromance movies, okay? I don’t even have time to feed myself dinner. I just slurp down old cans of cat food I find in the alley behind my house.
Anyhow, so special glial cells make myelin and deposit it along the axons of neurons, and everyone’s happy because now electrical signals can zip through the brain and body in milliseconds.
Unless, of course, you suffer from a demyelinating disorder like transverse myelitis or Guillain-Barre syndrome. Then your neural transmission slows to a crawl and you find yourself having a tough time, say, moving your limbs or the muscles that allow you to breathe.
The poster child of all demyelinating disorders is Multiple Sclerosis (MS), an autoimmune disorder in which the body’s own immune cells periodically “attack” the myelin sheaths of neurons. More specifically, the body attacks the glial cells that maintain the myelin sheath. After an attack, glial cells can recover and help repair the damaged myelin sheaths up to a certain point. However, the disease progresses when destruction of myelin outpaces repair. The repair process can also generate scarring (or sclerosis). Scar tissue is non-functional, and patients with MS will have characteristic scars or tangled myelin plaques on the white matter of their brains.
MS is a sad, difficult, frustrating disease. Unfortunately, it’s not terribly uncommon, and it’s more likely to occur in women. Before scientists discovered the physiologic underpinnings of the disease, some dismissed it as a psychosomatic manifestation in fragile or hysterical women. You know. Just women being dramatic. Not walking. Not moving. Not breathing. Darn women and their emotions!
Now we know much more about MS, and a slew of new information is on the horizon. You can bet I’ll take time out of my busy grad school schedule to blog about advances in MS therapies when they arise. Until then, put your myelin to use and go make me some dinner or something.
Vitals & Bits #11: The heart
The heart is a rectangular structure in the lower duodenum. It comprises three parts: the medulla, the cortex, and the mysterious outermost layer called the external bladder. While the exact function of the heart has eluded scientists for millennia, modern researchers believe the heart may play a role in defecation and extracorporeal data processing.
C’mon. You should know this one. Your heart is in your chest. You can probably feel yours palpitating away in a state of arousal as you read this brilliant blog entry. Freshly oxygenated blood in your lungs is delivered to your heart via your pulmonary veins. Your heart, which is essentially a massive four-chambered ball of muscle, then pumps this oxygenated blood throughout your body. As red blood cells flow through your tiny little capillaries, they unload their oxygen to your body’s tissues. Deoxygenated blood is then returned to your heart, which pumps it back through the lungs so it can pick up more oxygen. The oxygenated blood then travels back to your heart, which pumps it through the body again, and thus the great circle of life can continue.
Excess “bad” fat (like trans-fats from processed foods and animal fats from industrially produced meats), and toxins (like those found in cigarette smoke) cause inflammation, which damages your blood vessels. The heart has to work harder to pump blood through damaged vessels, which can weaken your heart over time. Fatty plaques can also build up inside your blood vessels. These plaques may eventually rupture and clog the arteries that supply blood to your heart or your brain, causing a heart attack or stroke. Not fun.
You only get one heart. Be good to it. Eat healthy. Take walks. Sleep. Smile and laugh a lot. Quit smoking. For reals.
In conclusion, I am right. As usual.
Vitals & Bits #10: Piloerector Muscles
You know that feeling you get on a beautiful Albuquerque summer evening, when dark purple clouds sit heavily on the northern horizon while the setting sun jettisons the vast western sky with its searing pink and orange afterthoughts? Ok, so I’m no lyricist. But you know what I mean. Our anxiety-riddled, consumption-driven, Facebook-centric modern lives are occasionally punctuated by moments so stunning that your hair literally stands on end.
The “hair standing on end” sensation of life’s finest “Aha!” moments is brought to you courtesy of your arrectores pilorum, or the small muscles attached to your hair follicles. When these muscles contract, they tug on your hair follicles, which causes your hair to stand on end.
The arrectores pilorum, or piloerector (pilo meaning “hair” and erector meaning, um, erection) muscles are not under voluntary control. These muscles are micromanaged by your autonomic nervous system, or the branch of your nervous system that does all kinds of cool crazy shit on its own without you thinking about it (like controlling your heart rate or digestive muscles.)
Certain physical sensations, like cold, will stimulate your autonomic nervous system to activate your piloerector muscles. This is because other furry mammals, like cats and dogs, control their body temperature by puffing up when they’re cold. This allows their fur to trap more body heat. Unfortunately (or rather, fortunately), humans don’t have enough hair to make piloerection an effective method of insulation. Because of this, the ability to piloerect is probably vestigial.
Emotionally-based sensations, such as fear, excitement, or awe can also stimulate the autonomic nervous system to activate the piloerector muscles. While we humans experience this “hair standing on end” sensation as a rather cosmic sixth sense, it is probably also a vestigial function of our hair follicles. You’ve probably seen a cat puff up when he’s spooked. Aside from being hilarious, piloerection allows cats to appear bigger and tougher when they encounter potentially harmful entities, like a neighbor’s dog or a rogue Tickle Me Elmo. Again, humans don’t have enough hair to make piloerection a very useful method of intimidation (though I am having fun picturing rival sports teams puffing up their hairdos as a form of pre-game posturing.)
Still, thinking of the itty-bitty, eager little muscles attached to my hair follicles fills me with appreciation for the fascinating minutia of the human body. While piloerection may not serve a definitive purpose in the human body, it at least allows me to feel all goosebumpy and electric when I contemplate the mind-warping mysteries of life.
Vitals & Bits #9: The Nipple
As a former maternal-newborn nurse, I’ve witnessed a variety of behaviors from new parents. These behaviors run the gamut from utterly predictable to amusingly zany. Some new moms ask for a beer the minute the baby has exited the birth canal, while others bedazzle their hospital rooms with unlit incense and prayer beads. But “new mom” behavioral quirks pale in comparison to what I’ve seen new fathers do.
While most fathers-to-be offer support, love and respect during the childbirth experience, some men seem to have poorly calibrated barometers for appropriate behavior. These inappropriate behaviors often involve their partner’s breasts or nipples. Why the nipple is so often the target of poor behavioral choices by men is still a mystery to me, but perhaps it has something to do with the fact that in our culture, the female breast is seen more as an iconic sexual object rather than a functional anatomical structure. It might also have to do with general lack of knowledge about how the breasts and nipples work.
For instance, on more than one occasion, I’ve witnessed men try to suck on their wives’ nipples during labor. While it’s true that nipple stimulation can help jumpstart a waning labor, I don’t understand why a man would choose to attempt this maneuver while the baby is halfway out of the birth canal. Nor do I understand why a man, lacking breasts or any medical background of his own, would criticize his girlfriend’s breastfeeding attempts and coach her on doing it “his way.” I’ve also seen men giggle childishly, crack dirty jokes or become visibly angry while their partner attempts to breast feed for the first time.
I was teaching one new mom how to get her baby latched on to her breast with the father reached out and pinched the tip of his wife’s nipple. “Ouch!” she exclaimed.
“Why on Earth did you do that?” I asked the man.
“I wanted to see milk squirt out,” he replied, shrugging.
Like many people, this guy thought that pinching the tip of the nipple would cause milk to squirt out like the stream from a water gun. His behavior betrayed not only a lack of sensitivity to his partner but also a lack of knowledge regarding the anatomy and physiology of the human body. Believing that the tip of the nipple is a singular milk spout is a pretty common misunderstanding, and I have found that lack of “nipple knowledge” occurs frequently among both men and women.
I explained to the man that contrary to popular belief, the female nipple doesn’t contain one hole in the middle. Instead, the whole nipple is studded with pores through which milk exits the breast. These pores are outlets to the lactiferous (milk-producing) ducts within the breast.
A breastfeeding baby doesn’t withdraw milk from the breast by sucking in the way that one sucks through the straw. Rather, suckling is more like a coordinated, rhythmic motion of the mouth, tongue, and jaw designed to compress and “milk” the lactiferous ducts. The baby has to get as much of the areola (or darkly-pigmented skin encircling the nipple) in her mouth as possible in order to compress these ducts and draw the milk out. It’s important that the baby get as much of the areola in her mouth as possible because the pigmentation of the areola roughly delineates where the ducts of the mammary glands are.
A baby who is just hanging on the tip of the nipple won’t have her mouth far back enough to compress the ducts and therefore won’t get any milk, just like squeezing the very tip of a tube of toothpaste won’t get you any toothpaste.
Also contrary to popular belief, breastfeeding isn’t a “natural, instinctual” process for most moms and babies. Breastfeeding is hard! Although I’ve seen a handful of first-time moms successful latch baby on the breast and continue breastfeeding without problems, this seems to be the exception to the rule.
There are a few reasons why breastfeeding is more of a challenge than an instinct. While babies are born with a suck reflex, the coordination of sucking, swallowing and breathing is a learned skill requiring sufficient neurological maturation to achieve. Breastfeeding is also a learned skill for moms, who often face obstacles like anatomical mismatch between the size of baby’s mouth and the size of mom’s nipple. Moms also have to learn how to position baby, latch baby onto the breast and read infant feeding cues (which seem totally inscrutable at first). Anxiety and misinformation don’t help matters.
I’m not trying to compare women to cows here, but we’re all mammals, so anyone who has ever milked a cow will have a good feel for how the lactation process works. Milking a cow doesn’t involve just squeezing the cow’s teat. Instead, your hand gently compresses from top to bottom and then pauses to allow the milk ducts to refill before repeating the motion. Milking a cow isn’t an intuitive, instinctual motion. It’s actually kinda difficult and requires practice before you get the feel for it. Similarly, breastfeeding requires learning and practice. Luckily, most mom and baby dyads, with a little appropriate guidance and patience, will totally rule at breastfeeding after a week or so.
Men who are curious about how lactating breasts work are advised to take a trip the dairy farm. Practicing on a cow is more socially acceptable than trying to suck, pinch or manhandle your partner’s nipples in the labor and delivery room.
Vitals and Bits #8: Bone Marrow
J.R. breezed confidently into the exam room, snapping her gum and chatting up a storm about pedicures with the nurse. By all accounts, she looked like your typical high school cheerleader: ponytail, muscular legs and a quick smile.
J.R.’s parents brought her to the doctor’s office because she’d complained of feeling unusually tired during cheer practice over the past couple of weeks. Other than that, she insisted that she felt fine. Her bright demeanor suggested excellent health. The doctor figured that J.R., like many teenaged girls, was probably anemic. She ran a few tests to check for anemia and for a common viral illness called mono.
When J.R.’s blood test results came back, the doctor stared at them for few minutes in disbelief. The nurse walked into the doctor’s office and saw the doctor sitting there motionless at her desk, jaw agape and eyes wide, staring at the computer screen.
“Oh shit,” the nurse exclaimed. “It must be really bad.”
And it was. J.R.’s white blood cell (WBC) count was through the roof. A normal WBC count doesn’t usually exceed 10. An elevated WBC count, such as 25, suggests infection. But a WBC count approaching 100 suggests leukemia, or a relatively rare type of cancer in which white blood cells undergo uncontrolled proliferation. An extremely elevated WBC count like this is a medical emergency, since the increased concentration of white cells in the blood stream can clog up small vessels like those in the kidney and brain.
The doctor called J.R.’s parents. She told them about J.R.’s elevated WBC count, and instructed them to take their daughter to the emergency room immediately. She hung up the phone with a heavy heart and cradled her head in her hands.
After the emergency room, J.R. would be hospitalized. She would undergo chemotherapy and radiation to kill off the cancerous white blood cells. Eventually, she would need a bone marrow transplant to help repopulate her body with healthy blood cells.
Mother Nature, in her infinitely creative wisdom, decided to utilize the snug, protected space inside of our bones as a nursery for newborn blood cells. Blood cell birth occurs in the bone marrow, or the spongy tissue inside our bones.
There are two different types of bone marrow: red and yellow. Red bone marrow produces blood cells, and yellow bone marrow is composed mainly of fat cells. At birth, all bone marrow is red. As we age, some red bone marrow (such as the marrow inside the long bones of our legs) is replaced with yellow marrow. About half of adult marrow is red, typically found in flat bones like those of the hip and shoulder blade.
A bone marrow transplant involves eliminating the recipient’s cancerous blood-forming cells and replacing them with healthy donor cells. The recipient and the donor must have compatible tissue types. Unfortunately, no one in J.R.’s family was found to be a compatible match. J.R. and her family clung to fervent, anxious hope that her doctors would find her a match in the bone marrow donor registry.
After several extremely tense weeks, J.R.’s doctors identified an appropriate donor. Several weeks after that, an extremely ill J.R. received a life-saving gift of healthy marrow cells from a total stranger.
These days, most bone marrow donation procedures are not all that different from a simple blood donation. If you register to donate marrow and are selected as a donor, you’ll be give drugs for a few days that tell your bone marrow to increase its productivity and churn a bunch of health new cells out into your circulatory system. These cells are then collected through a needle that goes into a vessel in your arm.
Some patients, like children or those with certain types of leukemia, fare better with a more traditional bone marrow transplant, in which donor marrow is harvested directly from the hip bone. If you donate this way, you’ll be numbed up before a doctor inserts a special needle into your hipbone to withdraw marrow cells.
Both procedures are minimally invasive with a very low risk of complications.
If you are interested in joining the national marrow donation registry, visit marrow.org for more information. I joined a few days ago, and it was easy breezy. The registry is especially in need of participants who belong to ethnic minority groups, such as Hispanics, Native Americans and African Americans.
Vitals and Bits #7: The Phagocyte
One liter of my blood harbors 6 billion:
a. Red blood cells
b. Molecules of alcohol
c. Professional phagocytes
d. Estrogen particles
e. Undocumented workers
If you answered C, you’re correct! Yay! Now collect your prize and keep your trap shut whilst I drop some knowledge on you.
Phagocytes are white blood cells that eat bad things like bacteria or dangerous substances. The ability to engulf harmful invaders means that phagocytes play a crucial role in immunity.
Many cells can perform phagocytosis (or the act of engulfing a foreign substance), but that’s not their primary gig. A professional phagocyte, on the other hand, is much like a competitive eater in that its only job is to ingest nasty stuff.
In the human body, professional phagocytes come in several different flavors. These include the roving monocyte, the voracious macrophage, the badass neutrophil, the flashy dendritic cell and the multitalented mast cell. These cells are able to sniff out the bad guys by sensing the chemical signals of invaders like bacteria. Damaged or dying body tissues also release chemical signals that alert phagocytes to move in and help with the cleanup effort. In this way, phagocytes facilitate healing and repair.
Not all invading organisms are vulnerable to phagocytes. Like Jonah sitting inside the whale’s belly, some bacteria have learned to actually live inside the phagocytes that eat them. Others have learned how to evade or injure phagocytes.
Generally speaking, though, the ability to phagocytose, or eat, is a fundamental prerequisite to life. Cellular ability to phagocytose evolved early on in the tree of life and has been incorporated into nearly every single life form since then.
You’ve probably touched a few million of your own phagocytes if you’ve ever popped a juicy zit. Pimple pus comprises a bunch of neutrophils that have eaten bacteria and then died, along with a bunch of dead macrophages that have eaten the dead neutrophils. Phagocytes eating phagocytes! I love it.
I feel a particular affinity for my phagocytes, given our mutual love of bingeing. I daresay my diet of cupcakes and merlot is a tad more delicious than the professional phagocyte’s diet of bacterial toxins and dead tissue. But to each her own, I suppose. Bon Appetit!
Vitals and Bits #6: The Cervix
The cervix, or the lower segment of the uterus, is sort of like a gateway into the uterus. The pear-shaped body of the uterus tapers into the cervix, which protrudes into the upper part of the vagina. During a pelvic exam, health care professionals can use a speculum to open up the vagina and look at the cervix. We swab it and scrape it to test for cancerous cells (a.k.a. a Pap smear) or bugs like Chlamydia.
The cervix has some cool party tricks. Normally the cervical os, which is the opening at the center of the cervix, is closed to prevent infections and other junk from climbing up into the uterus. But the os opens a little to allow menstrual fluid out every month. The cervix also opens in a major way during childbirth, to allow the baby to exit the womb.
The cervix can also produce fluid. During the time of the month when a woman has ovulated and is most fertile, her cervical fluid has a special thin texture that actually helps guide sperm up into the cervix to increase chances of fertilization. But during “infertile” times of the month, such as before ovulation, the cervix produces a thick acidic fluid that can kill off sperm or other potential uterine invaders. The cervix can also change its position and texture to either help or hinder sperm, depending on where a woman is in her menstrual cycle.
Finding a cervix during a pelvic exam can be really tricky. Sometimes you insert the speculum and open it up and the cervix pops into view, perfectly centered. But oftentimes the cervix isn’t so cooperative. Some women have a cervix that points to the ceiling, or toward the floor, or way off to the left or the right. These are all normal positions. If you’ve ever been told you have a tilted uterus or a cervix that’s difficult to find, it doesn’t mean you’re abnormal or less fertile than other women. In the vast majority cases, it’s perfectly normal and healthy to have a wonky womb.
The cervix, for all of its neat features, has some vulnerabilities too. It’s especially prone to infection by sexually transmitted infections. Some of these infections, like gonorrhea, can clear up after a course of antibiotics. Others, like human papillomavirus, like to hang around and cause problems like cervical cancer.
You can keep your little cervix happy and healthy by using condoms during intercourse and receiving your regularly scheduled Pap tests. The new Pap guidelines say you don’t have to have your first Pap test until age 21, and you don’t necessarily need one every year (more like every other year or once every three years, depending on your age group) unless there’s a problem. You can access the American College of Obstetrics and Gynecology’s new Pap guidelines here.
Women between ages 9 and 26 are also candidates for the HPV vaccine. This vaccine prevents women from catching the strains of HPV most likely to cause cancer. There are two vaccines on the market now: Gardasil and Cervarix. I think these vaccines will greatly reduce the financial and emotional burden of abnormal Pap tests and cervical cancer over the next few decades.