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Pregnant Pause: A look at ovulation, fertilization, and implantation

Posted by Courtney Smith on Wed, Feb 18, 2015 @ 01:09 PM

You know, I took a look back through all of the posts we've written over the last few years, and I noticed a glaring omission on our part. We've never once discussed pregnancy.

Part of the reason I think we've shied away from it is because everything else we talk about is equal opportunity—for the most part, everyone's body operates the same. It's only in the physiology of pregnancy and childbirth that we deviate from that. I am a firm believer, however, that knowledge can change the world, and so I think it's incredibly important that everyone—those who have the ability to have kids and those who don't—learn about pregnancy and how it changes the body.

Note: This blog post will be written using "perfect storm" circumstances. Remember: one can conceive pretty much at any time; biology isn't limited to certain weeks.

Weeks 1–2: Prime Time

When we talk about pregnancy, it's usually week to week. Seems annoyingly tedious, right? Wouldn't it be easier to keep track of things month to month? Nope!

Despite the fact that we refer to our pregnant friends and family as being "X months along," so many different things are happening week to week that there'd be far too much to fit into a monthly breakdown. In this "perfect" scenario, weeks 1 and 2 are counted even though one isn't pregnant. The first week starts on the last day of one's period.


A friend of mine once likened the body during ovulation (and the monthly cycle as a whole) to a very excited and unstable aunt. Picture it: she's painting the walls of the prospective nursery, setting up the crib, fixing decals of baby animals by the windows, and hanging a cloud mobile from the ceiling. She turns up the heat in the room and sometimes kicks the furniture a little when she gets too impatient.

Then, one of two things happens:

  1. The egg is fertilized! Huzzah! Our work is done.
  2. The egg wasn't fertilized. Well. It's time to burn the entire room to the ground.

Don't laugh. It's true. Periods are the worst.

Ovulation is the time during the cycle in which a mature egg is released from one of the ovaries and is sent down one of the fallopian tubes where it will wait to be fertilized. With the help of the hormone progesterone, the endometrium lining begins to thicken in preparation for fertilization—if the egg isn't fertilized, the lining is shed (a.k.a. burning the entire room to the ground).



You may be asking yourself, "What does that header even mean?" Well, I threw the famous Inception sound effect up there because “inception” rhymes with "conception," which is what we're going to be talking about. Inception has nothing to do with conception. Well, not really. Conception is a film that I'm writing starring Joseph Gordon-Levitt and my ovaries.

Week 3 is when conception happens. If you're wondering how that works, you're probably not old enough to be reading this.

During weeks 3 and 4, fertilization and implantation occur. Somewhere, the aunt in the nursery is throwing a party and putting the matches away, because there's going to be a baby!

When you hear “fertilize,” your mind probably goes to fertilizer, which is used to aid in the growth of plants. Fertilizer adds nutrients to help a seed grow, creating an environment perfect for the seed.


Fertilization is somewhat similar. Imagine an egg cell, or oocyte, is a seed. On its own, it really doesn't do much. It has the potential for life. But along comes a sperm cell, or spermatocyte, which penetrates the egg, much like the nutrients needed to kick-start the growth of a flower. The fused egg and sperm cells become a unique cell called a zygote.

Over the course of about 30 hours, the sperm cell's nucleus will fuse with that of the egg cell, combining their respective genetic material. About five days after fertilization, the zygote will divide into more cells and move down the uterus and implant into the endometrium as a collection of hundreds of cells, called a blastocyst, that continues to divide into more cells.


Week 4: Seriously, Though—
Don't Make Any Plans for the Next 9 Months

All right! Our crazy aunt is super happy and everything seems to be going swimmingly thus far. The blastocyst has implanted into the endometrium and is dividing, so now what? Well, this week marks the start of the embryonic period.

During week 4, the blastocyst will continue to divide until the cells branch into two groups: the first group includes the earliest baby cells, which will develop into the fetus, while the other group forms an environment that will protect and nourish the fetus—some of these cells will eventually develop into the placenta. When the placenta begins to develop, it sends a signal to the brain and endocrine system to start producing HCG (human chorionic gonadotropin), which is what pregnancy tests attempt to detect in blood (blood test) or urine (pee-on-a-stick test). When HCG is being produced, the body stops releasing eggs and the endometrium stays put.

However, the placenta isn't developed enough at this point to be the main provider of nutrients, so the blastocyst will be "fed" oxygen and other goodies by a microscopic circulatory system.

Stay tuned! We'll be tackling weeks 5–10 soon.


But don't stop there!

We've got an amazing new app coming soon, all about the anatomy & physiology of pregnancy! Be the first to know when it's available.

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Bedtime Stories: How this dad-daughter duo uses My Incredible Body

Posted by Lori Levans on Mon, Feb 09, 2015 @ 11:58 AM

It’s a wonderful thing to be able to answer questions that meet and maybe even exceed your kids’ curiosity factor. Why does this do that? As parents and educators, we want to be able to tell and even show kids the answers in a way that they can understand. Some concepts are harder than others.

Take human anatomy. It’s a huge area and can often be hard to explain. We’ve met one parent in particular who has a unique take on how he breaks down the information to his four-year-old daughter—often at bedtime!

Kevin C. Moore is a Hong Kong–based sports therapist. He is also the founder of Reembody, an online resource for education on human movement and biomechanics. He has been using Visible Body products like Muscle Premium and Skeleton Premium in both capacities for a long time and recently purchased our kids' anatomy app, My Incredible Body, for his daughter, SJ.

What prompted you to buy the app? Has your daughter been asking questions about how the body works?

SJ is four years old, exceedingly precocious, and very interested in the human body. I work as a sports therapist, so bones, muscles, and injuries are regular topics of casual conversation around our house.

What interests her in particular?

SJ is fascinated by the process of injury and healing; she’s quick to ask and comment anytime she sees that someone is hurt. She seems particularly interested in bones, but I suspect that this is because the skeleton, as a whole, resembles a person, making it easier for her to relate to.


Photo: Kevin and SJ

Can you describe a scenario of how you use the app with SJ?

We use My Incredible Body like we would one of SJ’s storybooks; it’s much less like a “lesson” and more like story time. We’ll cuddle up together and read/watch through it like we would read Beatrix Potter or one of her many dinosaur books.

How does she interact with My Incredible Body?

She typically does the tapping, though I’ll reach in and manipulate things that I want to show her, or that she’s having a hard time navigating. She asks questions, we make up narratives; there’s a lot of talking.

What does SJ enjoy most about the app?

The videos are a big hit—all of them. As she gets older I imagine the more interactive portions will become more and more interesting to her. At the moment, the animated hand closing and opening in grip is probably her favorite thing to explore. She’s tickled by the sound effects.

Do you feel that the design is helpful in promoting learning? How so?

The sound design, in particular, is really good. The music and sound effects go a long way to creating an immersive environment for her. There’s enough movement on the screen to keep her eyes attached, but not too much to be distracting.

What do you think is particularly effective?

I think it was a good choice to show the semi-transparent outline of a kiddo body over the skeleton portions; it gives a really clear idea of what we parents mean when we say “you have a skeleton inside you right now!”


What do you like best about the app?

The variety: so many different systems and so many different methods of interaction. Also, the touch-response lessons that come with each structure. Also, I’m still generally impressed with the modeling of the tissue structures, though that’s much more of interest to me than the kiddo, I think.

Would you recommend this app to teachers?

Are you kidding? Yes! Between the videos and the exploratory functions, it’s easy to make it into a story they can follow. They can chime in with experiences they’ve had with their own bodies, relating what they see to what they feel.

For your little anatomy explorers:

Every kid wants to know how and why things work. Help them learn how and why their own bodies work with My Incredible Body!

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Topics: teach kids anatomy

The Endocrine System: Hypothalamus and Pituitary

Posted by Courtney Smith on Fri, Jan 02, 2015 @ 03:31 PM

Are you hot right now? Cold? Maybe you're like Goldilocks and are just right. What about your height? Are you tall? Average? Short? Maybe your metabolism is lightning fast and you're always hungry, or maybe it's a bit slow and you stay full longer. All of these—regardless of which one you identify with—are regulated by the endocrine system.

What is the endocrine system? It's a network of glands throughout the body that regulate certain body functions, including body temperature, metabolism, growth, and sexual development. Though there are many glands, today we’ll focus on just two: the hypothalamus and the pituitary gland.

Hypothalamus-pituitary-gland-brain-1(Hypothalamus and pituitary, highlighted in blue)

I'm going to be throwing a lot of information at you, dear reader, so brace yourself!

Hormone Reaction Regulation


It’s no secret your brain is one busy place—neurons move at incredible speeds, synapses are constantly firing, blood is pumping, and glands are producing hormones. These glands, specifically the hypothalamus and pituitary, are working all the time to keep your body running at optimal performance. Every hormone the endocrine system releases follows a basic set-up: a signal is received, hormones are secreted, and the target cell undergoes changes to its basic functions.


The almond-sized hypothalamus is located below the thalamus and sits just above the brainstem. All vertebrate brains have a hypothalamus. Its primary function is to maintain homeostasis (stability of the internal environment) in the body.


The hypothalamus links the nervous and endocrine systems by way of the pituitary gland. Its function is to secrete releasing hormones and inhibiting hormones that stimulate or inhibit (like their names imply) production of hormones in the anterior pituitary. Specialized neuron clusters called neurosecretory cells in the hypothalamus produce the hormones Antidiuretic Hormone (ADH) and Oxytocin (OXT), and transport them to the pituitary, where they're stored for later release.

Think of the hypothalamus as the pituitary's older sibling—it not only controls the actions of the pituitary but it secretes at least nine hormones to the pituitary's seven.

Pituitary Gland

Attached to the hypothalamus, the pituitary gland is a pea-sized, reddish-gray body that stores hormones from the hypothalamus and releases them into the bloodstream. The pituitary consists of an anterior lobe and a posterior lobe, each of which have distinct functions.


Pituitary: Anterior Lobe (Adenohypophysis)

The anterior lobe (or adenophyophosis) secretes hormones that regulate a wide variety of bodily functions. There are five anterior pituitary cells that secrete seven hormones:



Secrete human growth hormone (hGH), aka somatotropin, which stimulates tissues to secrete hormones that stimulate body growth and regulate metabolism.


Secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which both act on the gonads. They stimulate the secretion of estrogen and progesterone, maturation of egg cells in the ovaries, and stimulate sperm production and secretion of testosterone in the testes.


Secrete prolactin (PRL), which initiates milk production in the mammary glands.


Secrete adrenocorticotropic hormone (ACTH), which stimulates the adrenal cortex to secrete glucocorticoids (like cortisol). Also secretes melanocyte-stimulating hormone (MSH).


Secrete thyroid-stimulating hormone (TSH), which controls secretions of the thyroid gland.


This table represents the types of hormones secreted by the cells of the anterior pituitary.


Target Area


Human-growth hormone (hGH)


Stimulates tissue growth in the liver, muscles, bones, as well as protein synthesis, tissue repair, and elevation of blood glucose levels.

Thyroid-stimulating hormone (TSH)

Thyroid gland

Stimulates thyroid gland to secrete thyroid hormones.

Follicle-stimulating hormone (FSH)

Ovaries and testes (gonads)

Stimulates development of oocytes (immature egg cells) and secretion of estrogen in females; stimulates sperm production in the testes in males.

Luteinizing hormone (LH)

Ovaries and testes (gonads)

Stimulates secretion of estrogen and progesterone, including during ovulation, in females; stimulates testes to produce testosterone in males.

Prolactin (PRL)

Mammary glands

Stimulates milk production.

Adrenocorticotropic hormone (ACTH)

Adrenal cortex

Stimulates secretion of glucocorticoids (cortisol) by the adrenal cortex during the body’s response to stress.

Melanocyte-stimulating hormone (MSH)


When in excess, can cause darkening of the skin; may influence brain activity (its exact role unknown—there is very little MSH in humans).


Pituitary: Posterior Lobe (Neurohypophysis)

While the anterior lobe shoulders most of the work in producing hormones, the posterior lobe stores and releases only two: oxytocin and antidiuretic hormone (ADH), or vasopressin.





Oxytocin (OT), aka the "love" drug

Secretes in response to uterine distention and stimulation of the nipples.

Stimulates smooth muscle contractions of the uterus during childbirth, as well as milk ejection in the mammary glands.

Antidiuretic hormone (ADH), or vasopressin

Secretes in response to dehydration, blood loss, pain, stress; inhibitors of ADH secretion include high blood volume and alcohol.

Decreases urine volume to conserve water, decreases water loss through sweating, raises blood pressure by constricting arterioles.


Pituitary Disorders

Even though it's very small, the pituitary gland isn't free from ailment—nothing is completely foolproof, after all.

Most disorders of the pituitary glands are tumors, which are common in adults. These growths are not  considered brain tumors, nor are they always malignant. In fact, they're almost always benign in nature! There are two types of pituitary tumors—secretory and non-secretory. A secretory tumor produces too much of a hormone, while a non-secretory tumor does not. Regardless, if the tumor is big enough, it can hinder normal pituitary function. These tumors can be removed, or monitored and controlled with medication.

Problems caused by tumors fall into certain categories:

  • Hyposecretion: Too little of a hormone is produced, interfering in normal function.

  • Hypersecretion: Too much of a hormone is produced, interfering in normal function.

  • Mass effects: The tumor presses on the pituitary or other areas of the brain, causing pain, vision issues, or other problems.

While the pituitary and hypothalamus can run into the above issues, on the whole they work a balancing act on your body. So the next time you're feeling juuuust right, you can thank the pituitary, hypothalamus, and all the other organs of the endocrine system.


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Topics: anatomy and physiology

The Seven Coolest Medical Stories of 2014

Posted by Courtney Smith on Tue, Dec 09, 2014 @ 03:47 PM


It's that time again! Last year, we rounded up seven of the wackiest and/or most amazing stories the medical world had to offer. Let's see if 2014 can top them.


After suffering stab wounds to the back in 2010, Darek Fidyka had been paralyzed from the chest down. Today, he is walking—even driving and living independently!—with the aid of a metal frame and nose cells.

During his attack, the knife severed his spinal cord. Using specialized cells taken from his nose—olfactory ensheathing cells, to be precise—a "bridge" was created over the injury site, and nerve cells could regrow across the scar tissue. Nineteen months of treatment later, Fidyka has recovered some voluntary movement and sensation in his legs.


Ever been at the beach, wading in a tide pool or lagoon, and seen one of these guys skittering across the sandy bottom? Where I grew up, horseshoe crabs were in abundance, and my dad used to pick them up so we could see what they looked like underneath. My dad is a steadfast conservationist and he really imparted upon me, my sister, and our friends just how important everything in the ocean is, including the odd-looking horseshoe crab. I don't know if he knew how important they are, though, since they're now rocking the medical world!

Horseshoe crabs are being harvested (but not killed) for their blue blood, which identifies and congeals around toxins and bacteria, trapping threats inside a gel-like seal to prevent them from spreading. Forty-five minutes of exposure to horseshoe crab blood will reveal endotoxins from bacteria that otherwise avoid detection, and is sensitive enough that it can isolate a threat the equivalent size of a grain of sand in a swimming pool. Intravenous drugs and medical equipment, such as needles, must first pass through the crabs' blood before use. Because of this, thousands of us survive all sorts of medical procedures.

Over 600,000 horseshoe crabs are caught each year during mating season and "donate" about 30% of their blood in special facilities in the United States and Asia. However, with population numbers reduced by 75–90% in the last 15 years, and with 10–30% of crab donors dying in the process, finding a balance is of the utmost importance. Biologists are looking for alternatives to lessen the strain on the crabs during the blood-taking procedure and for the horseshoe crab population as a whole.


Three-dimensional printing is all the rage, and people are printing all sorts of things—cars, casts, and sculptures. People are even 3D printing 3D printers! Last year, we talked about how 3D printing of organs, such as hearts, would revolutionize the medical world in about a decade, and it's still on track to do so. However, one South African man couldn't wait that long and decided to fast-track his way to some new fingers.

In 2011, Richard van As, a carpenter, accidentally cut off four fingers on his right hand when the saw he was using slipped. Instead of mourn the loss (and embrace what was quite possibly the end of his career), he began searching online for alternatives to expensive prosthetics. He stumbled upon the video of mechanical effects artist Ivan Owen, and together the pair developed mechanical fingers for van As.

But they didn't stop there! They went on to form the company Robohand, which provides affordable 3D-printed prosthetic arms and hands to amputees all around the world!

Luke Skywalker may want to give them a call.


Yes, you read that right. "Why?" you may ask. Well, why not?

For the first time ever, scientists are able to transform human adult cells into working bits of intestine in mice. Small sections of human intestine are transplanted into the mice, and from there the tissue balloons into thumb-sized nuggets that look and function like real human intestine.

"Yeah, but why?" you're probably asking again. Well, let's take a look at how many bowel issues people have every year—Crohn's disease affects around 700,000 people and bowel cancer is diagnosed in 130,000 people (both in the United States alone!). These working bits inside mice could help tailor treatments; scientists could test drugs on the intestine nuggets to see how they respond without subjecting a person to a barrage of tests.


A surgical team at St. Vincent's Hospital Heart and Lung Transplant Unit in Sydney, Australia, has successfully performed three transplants with donor hearts that had stopped beating for 20 minutes. Two of the patients who received the hearts are doing well, and one remains in intensive care.

Donor hearts were submerged in a ground-breaking preservative solution developed by the hospital and the Victor Chang Cardiac Research Institute. They were then connected to a circuit that kept them beating and warm.

The St. Vincent’s team hopes this procedure will greatly boost the supply of donor organs.


Of the many mental disorders afflicting people today, schizophrenia is viewed as one of the worst. Just over 1% of the American population has been diagnosed with the disorder, which causes symptoms that can include paranoia, delusions, auditory hallucinations, and impaired behavior. It's always been diagnosed as one disorder.

However, a new study led by C. Robert Cloninger of Washington University School of Medicine in St. Louis reveals schizophrenia isn't just one disorder, but eight with genetically different causes. This could completely change how schizophrenia is diagnosed and treated.


Ebola has always been a pressing issue, but its recent introduction to America thrust it into an even brighter spotlight. The World Health Organization reports that around 12,000 people in West Africa (mostly Liberia) have died from the illness, and there could be 10,000 new cases per week if the threat isn't stopped.

Finding a way to prevent new cases is the most important thing, and a new vaccine could be the thing that finally does this. Produced by Glaxo Smith Kline, the ebola vaccine passed primate trials and was being tested in the first round of human trials in October. The vaccine was tested on 40 healthy volunteers in Mali, including nurse Ruth Atkins, who got the first dose. In addition to those 40, 20 are being tested at the National Institute of Health in the United States, and 60 more in the United Kingdom.

Another vaccine is in the trial stages at the Walter Reed Army Institute of Research, licensed to Newlink Genetics. 


And that brings 2014 to a close.

Here's to 2015 and the new and interesting stories it will bring!

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Common Ligament Injuries and Disorders

Posted by Courtney Smith on Fri, Nov 14, 2014 @ 02:29 PM

Ligaments are the glue that holds us together. I kind of mean that literally—ligaments are tight, fibrous bands that hold together bones and facilitate movement of the joints. Your body is chock full of them! And as such, there are usually a fair amount of injuries to go with them. Why can't we have nice things?

Here are five common injuries or disorders involving the ligaments.

(Note: If you have Skeleton Anatomy Atlas for iPad or iPhone, tap the pictures on your device to launch them as interactive 3D models!)


1. Torn ACL

If you attended a secondary school as enthusiastic as mine was about sports, then you knew quite a few people who were on crutches because they tore their ACL. Of all the common ligament injuries in the knee, a torn ACL is at the top.


The anterior cruciate ligament (ACL) attaches to the tibia and femur to help form the knee joint. The cruciate ligaments (anterior and posterior) are situated in the middle of the joint and form the shape of a cross (hence the name "cruciate"). The ACL acts as a stabilizer of the knee, preventing the tibia from sliding forward, so a tear to the ligament causes instability and, in some cases, the knee to "give out."


2. TMJ Disorder

The temporomandibular joint (TMJ) is where the mandible and temporal bone articulate. The ligaments of the joint reinforce it. The joint—a hinge joint, to be specific—allows for all kinds of movement, such as flexion, extension, and rotation.


TMJ Disorder (TMJD) is an umbrella term for various issues with the joint, usually involving the muscles of mastication and the surrounding nerves and ligaments. The most common symptoms are a restriction of movement in the joint, as well as pain.

I, myself, have TMJD. I experience frequent "clicking" of my jaw, pressure at the joint, and sometimes it even locks up a bit! In high school, I went through packs of gum the way heavy smokers go through packs of cigarettes, which was probably the cause.


3. Sprained Ankle

If you haven't experienced a sprained ankle… I'm guessing you can actually fly. Sprained ankles are one of the most common injuries to the body, and can be caused by simply stepping the wrong way on an uneven surface. According to the American Orthopaedic Foot & Ankle Society, nearly 25,000 people sprain their ankle every day. In fact, in the 4th grade I had a sprained ankle almost every other week. I'd be very surprised if there were any pictures of me not on crutches from that year.


An ankle sprain occurs when one or more of the ligaments on the outer side of the ankle are stretched or even torn. Symptoms of an ankle sprain include swelling of the ankle, pain, and the inability to bear weight on it.

Most sprains will heal with the help of rest and the application of ice packs, but in severe cases surgery may be needed to help repair the ligament(s).


4. Plantar Fasciitis

Also known as "jogger's heel," plantar fasciitis is the pain and inflammation of the plantar fascia—the thick, strong band of connective tissue stretched along the bottom of the foot, connecting the calcaneus to the toes.


While the plantar fascia is very strong, repetitive stress can cause micro-tears in the ligament, which can lead to stabbing pain usually focused at the heel or the arch of the foot. Plantar fasciitis is common in joggers and runners, and contributing factors include obesity, strenuous activity without proper stretching, high arches, and tight calf muscles.


5. Shoulder Separation

If you receive a blow to the shoulder or fall on your hand (or play football when you're way past your prime, Dad), you may experience an injury called shoulder separation.


Also known as acromioclavicular or AC separation, it's a common injury to the acromioclavicular joint. It is not the same as a dislocated shoulder, in which the humerus pops out of the glenoid cavity, but rather a tearing of the ligaments connecting the scapula to the clavicle. The acromioclavicular ligament in particular is the ligament commonly torn with this sort of injury.

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The Toxic Substance Treatment Plant: Liver Anatomy

Posted by Courtney Smith on Wed, Nov 05, 2014 @ 01:49 PM

The liver is the friend of many—if a few of my friends from college are any indication, it’s the best friend of some. I fondly remember being at a party where a boy named Andrew loudly proclaimed his love for his poor, overworked, and underpaid liver in the form of a poem, to the delight of a group of revelers who, like Andrew, were feeling no pain in that moment. It was an interesting ode. I gave it a solid 7 for effort.

Before I go any further, you ought to locate your liver. It would be weird to talk about something in your body without knowing exactly where it is. Put a hand underneath your sternum, in the space between the false ribs. Below your hand is your liver, the largest gland in the human body and the second largest organ (your skin is the first!). The liver is located in your abdominal cavity, just below the diaphragm. I’m sure your doctor has palpated it during a physical exam to make sure it feels normal.


But what is it about this large and busy organ that helps (and sometimes hinders) us? Read on to find out!

1. Busy, Busy, Busy: The Functions of the Liver

While, yes, the liver serves as the body’s control board when one is drinking alcohol, the liver does a whole bunch of other important stuff, including metabolic and digestive functions. The functions of the liver include helping to digest fats, maintaining glucose balance in the blood, producing blood proteins, detoxifying blood, and storing vitamins.

Check out this table to get the rundown:


 Look at all those functions! The liver isn't even in the vicinity of messing around.

2. What, Where, When, How: The Anatomy of the Liver

If you look at the liver, you’ll probably see a dark red, uh … blob. There, I said it. It looks like a blob. I promise it’s anything but! There are two ways to talk about the liver: by its external appearance (lobes) and by its functional units (segments).

We’re going to do both.


The Lobes of the Liver

The falciform ligament that divides the small left lobe from the larger right lobe is visible.


Inferior-anterior view

The quadrate lobe and caudate lobe have between them an opening for the hepatic portal vein.


Inferior-anterior view.

The Segments of the Liver

Named the Couninaud Classification (bit of a tongue twister) after the physician who first described them, the eight segments (one segment is classified into a superior and inferior segment, so it's more like nine) of the liver are named for their respective functions. Each segment provides distinct vascular inflow, outflow, and biliary (bile) drainage.


These segments are often called surgical segments of the liver because they are used in resections to preserve their functions.


3. Besties: The Gallbladder and Liver

The liver doesn’t act alone—everyone needs friends, after all. On the underside of the liver is a bulbous, musculomembranous sac called the gallbladder. It serves as a reservoir for the bile that is secreted by the liver. Bile is a greenish-brownish bitter fluid that helps digest lipids in the small intestine. 


Secreted into the common bile duct, via the common hepatic duct from the liver, or the cystic duct from the gall bladder, bile can either be secreted directly into the duodenum or stored for later use in the gallbladder.


4. Why can’t we have nice things? Diseases and the Liver


If you didn’t read that as “diabeetus” in Wilford Brimley’s voice, congratulations—you’re a better person than I am. Diabetes mellitus, or just simply diabetes, is a group of diseases that affects how the body uses glucose. For those of you playing the home game, glucose is your brain’s main fuel. It’s also an important source of energy for your cells.

Diabetes has two main causes: the loss of insulin-producing cells in the pancreas (type 1), or insulin resistance (type 2). Both affect the liver’s ability to break down glycogen (synthesized and stored mainly in the liver), absorb glucose to make glycogen, or stimulate the transport of these sugars to other parts of the body.



Hepatitis is an inflammation of the liver, due to various causes, such as viruses, toxins, autoimmunity, or hereditary conditions. There are different types of the hepatitis virus, but we're going to talk about two: A and B.

Hepatitis A is spread via contact with an infected person’s feces. While you might be thinking, “How could I possibly come into contact with that?!,” think about how many people in the world don’t wash their hands. There’s also untreated drinking water.

Most people are familiar with hepatitis B, which is spread via an infected person’s bodily fluids, such as blood or semen. Reusing needles is a common way to spread the virus, as is unprotected sex. The virus can also be passed from an infected woman to her baby at birth.

Symptoms of hepatitis include yellowing skin and eyes, known as jaundice, and feeling as though you have the flu. Dark-colored urine and pale stool are also signs. In some cases, there may not be any symptoms. While hepatitis usually clears up on its own in a few months, if it goes untreated it’s called chronic hepatitis, which lasts a lifetime. Chronic hepatitis B can lead to scarring of the liver, liver failure, or liver cancer. A simple blood test will determine whether or not you’re infected.


Other diseases

As the repository and treatment plant for toxic substances, it’s unsurprising that the liver has a number of diseases associated with it. The most widely spread diseases of the liver besides hepatitis are toxic liver disease and cirrhosis. Toxic liver disease is an umbrella term for any disorder caused by various drugs or environmental chemicals such as alcohol. Cirrhosis, caused usually by heavy, long-term drinking, is the formation of fibrous tissue instead of liver cells that have died due to damage. Cirrhosis causes chronic liver failure.

That reddish blob in your abdomen is responsible for a lot. So, thank your liver when you go out for a few drinks with friends or when you’re firing up your muscles or your brain to do… pretty much anything. 


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Zybright Guest Post: Amazing Anatomy in Motion

Posted by Courtney Smith on Fri, Oct 24, 2014 @ 03:46 PM

Try holding as still as you possibly can. No matter how much you’re not moving, there are tons of things inside you that are! Your body is always on the go go go, even when you’re sound asleep. From your beating heart, to your firing neurons, to your moving muscles, to your expanding and contracting lungs, you’re in constant motion all the time.

Let’s take a look at five things in constant motion! Follow along in the video to see them in action. 





1. Arteries and Veins


Your body is full of a complicated network of arteries and veins that bring blood from and to the heart. They look a bit like streets on a map, don’t they? The red streets are arteries, which carry blood that is full of oxygen to every part of your body. Your organs, muscles, and tissues all need oxygen and blood to stay healthy. Once your organs and tissues have taken all the oxygen from the blood, the blue streets—veins—carry it back to the heart, which pushes it to the lungs so it can be shot full of oxygen again. Once the blood is oxygen-rich, the heart pumps it back out through the arteries, and the cycle begins again!


2. The Ear


Do you hear what I hear? Your ears are constantly picking up sounds from the world around you. While you may think of your ear as being one whole structure, it’s actually three sections that all work together. The three sections pass vibrations from the air through your ear to special nerves, which then transmit the vibrations to your brain for interpretation. Your brain can tell one specific vibration from another, which is why you know the difference between the honking of a car and the honking of a flock of geese!


3. Moving Muscles

Your muscles operate throughout your body, working with bones, tissues, and even other muscles to keep you stable and strong. Are you still trying to stay as still as possible? Guess what: your muscles are still moving! Certain muscles, like the ones that help you breathe, never stop, even when the rest of you does. You have over 600 muscles in your body and they make up about half of your body weight.


4. The Pupil


While standing in a bright room, stare at your reflection in a mirror. Now, shut off the light. Wait a moment, then—making sure you’re still looking in the mirror—turn the light back on. See how your pupil shrinks?

The iris (the colored part of your eye) is a special kind of muscle that is attached to the pupil and pulls it open or closed depending on how much light should come through. When you flicked the lights back on and your pupil shrank, your iris pulled it shut to allow a small amount of light into your eye. As you adjusted to the sudden burst of light, your iris pulled it open slowly until it was nice and wide, letting as much light in as needed.


5. The Small Intestine

Sometimes your tummy rumbles when you’re not hungry. Your digestive system is active, even when you’re not actively eating. The small intestine is made up of smooth muscle (the kind of muscle that makes up the stomach, bladder, reproductive systems, and other structures), and its walls are always moving.

When your body is digesting food, the stomach turns the food into liquid and sends it into the small intestine. The small intestine’s job is to separate nutrients from the liquid that are eventually sent to the rest of your body by your blood.


The images and most of the text comes from My Incredible Body: Amazing anatomy just for kids.

Want to see more content? Download our free resources, including eBooks.

Ready to buy the app? It is available for iPhone and iPad, PC or Mac DownloadAndroid devices, and Windows Touch devices

Topics: teach kids anatomy

Five Fast Facts about Skull Anatomy

Posted by Maite Suarez-Rivas on Tue, Oct 14, 2014 @ 01:10 PM

Twenty-two bones come together like a puzzle to make the skull. Some bones give shape to the face, others protect the brain. But it's not all bones! The skull also includes cartilage (put your finger on the tip of your nose and wiggle it) and ligaments (open and close your mouth if you want to use them).

Here are some other fast facts about the skull.



1. There is a difference between the skullcap and the braincase.

The bones that enclose and protect your brain (like a braincase!) form the neurocranium. Need a list of those bones? Here it is: The bones of the neurocranium are the ethmoid, sphenoid, frontal, and occipital bones (one each), and then there are the parietals and temporals (two each). If you take the ethmoid and the sphenoid out of that list you have the bones of the calvaria (the skullcap). The calvaria is a subdivision of the neurocranium. When you talk about the calvaria, you are talking just about the bones on the superior part of the cranium. 


The calvaria (right) is a subdivision of the neurocranium (left). (This image is from the free Skeleton Anatomy Atlas for iPhone/iPad. Have that free app installed and reading this blog on your iPad or iPhone? Tap on the photo to see the image in 3D!)

2. The facial skeleton doesn't include all those teeth or the cartilage that shapes your nose.

Fourteen bones form the facial skeleton. There is the mandible (jaw bone) the vomer (gives shape to your nose) and then a series of paired bones (as in there is a left and a right): the nasals, maxillae, lacrimals, zygomatics, palatines, and the inferior nasal conchae. The face is also formed by the nasal cartilages (a group of connective tissue structures that give shape to the framework of your nose) and by the teeth (the upper arch of teeth are attached to the maxillae and the lower arch of teeth are attached to the mandible).

3. The skull is full of foramina.

Foramina are apertures, sometimes called canals, scattered throughout the bones of the skull. These openings commonly function as passageways for nerves and vessels. At the base of the skull, in the occipital bone, is the largest foramen of the skull, the Foramen magnum. Vertebral arteries and the spinal cord pass through this opening.


The foramen magnum is the largest of the many foramina in the skull.

4. When you open and close your mouth you are using your tempromandibular joint.

Touch the area of your face right in front of your ear. Now open and close your mouth and you will feel your mandible moving. Each temporomandibular joint is formed by the temporal bone (r,l), the mandible, and ligaments that surround the joint. These ligaments reinforce the area where the cranium articulates with the mandible.


A number of ligaments reinforce the temporomandibular joint. The main "hinge" of the temporomandibular joint is the sphenomandibular ligamenta flat, thin band that connects the sphenoid bone to the lingula of the mandibular foramen.

5. The full-of-foramina ethmoid and the L-shaped palatines are the only skull bones you can't feel by touching your head or face.

The ethmoid bone, located at the roof of the nose and between the eyes, has tiny foramina. Nerve cells in the nose detect odors, carry those signals through the foramina in the ethmoid, and to the olfactory bulbs. From there, the signals move along the olfactory tracts to the brain. The palatine bones help give shape to the back of the roof of the mouth, the floor of the nasal cavity, and the floor of the orbits.


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Topics: learn skeleton anatomy

Zybright Guest Post: Puberty—Your journey from kid to grown-up

Posted by Lori Levans on Fri, Oct 03, 2014 @ 03:44 PM

Hey everyone: We know it can be awkward to talk about the changes that are happening to your body. But it’s a part of life that everyone goes through!

All of these changes are thanks to a little thing called puberty. Puberty affects both boys and girls. Think of it as your journey from kid to grown-up.

So, let's talk about these changes. We can start at the beginning with some biology. 

Reproduction basics

Boys and girls each have sex cells. Boys have sperm and girls have eggs. They are essential to create a new life—in other words, a baby.


During puberty, the testicles begin producing sperm, the male sex cells. From the testicles, sperm travel in a fluid called semen. When a sperm swims up to join with an egg—called fertilization—these cells begin multiplying to create a baby. The image above shows you what it looks like when sperm move toward the egg.

Eggs are the female’s sex cells. When girls begin puberty, a single egg gets released from an ovary each month. When a sperm and egg unite (yup, that’s fertilization) they multiply and create more cells that eventually create a baby. When an egg does not meet a sperm, it travels out of the body during menstruation.


Puberty 101: Ladies first

So now that we have some of the basics covered, let’s talk about those body changes. We'll start with changes unique to girls.

Puberty is the time when a girl’s body starts changing and preparing for later on in life for a potential pregnancy.



A girl’s body starts practicing creating a “nest” in her uterus as a place for a baby to grow. This nest is a lining of blood and tissue. In the image above, you're looking at the uterus and its lining. See the egg on its way toward the nest?

About once a month, one of her ovaries releases an egg cell. If this egg cell is not fertilized, her body will know that the lining (or nest) is not needed. The uterus slowly sheds the lining of blood and tissue, which trickles out of the girl’s body through the vagina. This is called having a period—or menstruation.

A girl’s period can last from 2 to 7 days. The following month, the uterus practices preparing a new lining and the process starts all over again.

Now, on to the boys

One change that’s unique to boys is that their voices change.



A boy’s voice gets deeper because his voice box (shown above) gets larger during puberty. The larger it gets, the lower the sound it makes. It has to do with the way the air moves through the voice box.

In fact, a boy’s voice box will grow so much that it pops out at the front of his neck. It’s often called the Adam’s apple.


Changes that happen to everyone

Here's an inevitable reality that happens to both boys and girls: everyone gets pimples.



When boys and girls go through puberty, new hormones are produced in the body. These hormones stimulate the glands in the skin to produce more oil. Pores can become clogged up with this excess oil and bacteria (germs) can get trapped, causing pimples or acne.

Sweat and body odor are another set of realities during puberty.



You have been able to sweat since birth to cool off when you get hot. During puberty, you may notice that you sweat more under the arms than you did before. When boys and girls start puberty, the hormones you create change the way you sweat — and the composition of your sweat changes. When the sweat meets your skin, the bacteria that normally lives on you creates the odor.


The images and most of the text comes from My Incredible Body: Amazing anatomy just for kids.

Want to see more content? Download our free resources, including eBooks.

Ready to buy the app? It is available for iPhone and iPadAndroid devices, and Windows Touch devices

Editor's Note: This content was reviewed by Chrystal deFreitas, MD, FAAP, founder and president of www.healthychats.com and practicing pediatrician at Carmel Valley Pediatrics based in San Diego, CA.

Topics: teach kids anatomy

Zybright Guest Post: The 5 Stages of Digestion—Anatomy Just for Kids

Posted by Lori Levans on Mon, Sep 15, 2014 @ 11:35 AM

Food is the fuel that gives your body the energy it needs to go, go, go! Your digestive system moves food that you eat through your body. The food goes through lots of changes as it’s digested so the rest of your body can get what it needs. 

C’mon, let’s take a tour of the five stages of digestion! If you have the app, My Incredible Body, you can follow along!

1.    Come on in! The oral cavity is the doorway to digestion.

 science app for kids image of small intestine

Your mouth, teeth, and tongue form the space that’s called the oral cavity, and where your food begins its adventure. As soon as you take a bite, your food is already changing: your teeth are making it smaller, your saliva (spit) is making it wet, and your tongue helps push it together so you can swallow it.


2.    Next, let’s go down the elevator, otherwise known as your esophagus.

 Learn about the esophagus with My Incredible Body: Amazing anatomy just for kids!

You have a long tube called the esophagus that brings food from your oral cavity to your stomach. If you chew, swallow, and then count to five slowly, you’ll get an idea of how long it takes for food to move down your esophagus and into your stomach.


3.    Now, into the stomach. Come on in, there’s lots of room!

 Learn about the stomach with My Incredible Body: Amazing anatomy just for kids!

Do you know that your stomach is super-stretchy? It can grow to more than double its size, especially after you eat a big meal. Inside your stomach are folds that allow it to expand and contract. After the food enters your stomach, muscles squeeze and churn to mix it with gastric juices, helping to break it down.


4.    Welcome to the small intestine. Make yourself at home; this is going to take a while.

 Learn about the small intestine with My Incredible Body: Amazing anatomy just for kids!

The small intestine is shaped like a long tube, but it’s all scrunched up. If you stretched it out, you could wrap it around your waist more than 10 times! Why is it so long? So your body has lots of time to get out all the nutrients from your food. Inside your small intestine are finger-shaped sponges that absorb nutrients from a meal and pass them into your blood, which delivers them to the rest of your body.


(Here’s a fun kids’ science project: Have them compare the length of a hose to the length of the small intestine. They’ll be surprised something so long can fit neatly into their body!)


5.    Last stop: the large intestine.

Learn about the large intestine with My Incredible Body: Amazing anatomy just for kids! 

Your large intestine is where your body forms waste. Everything you’ve eaten that your body doesn’t want to keep is pressed together here. Water gets squeezed out and absorbed into your body and what’s left leaves your body and goes into the toilet. Plop! Goodbye!


All of the images and most of the text come from My Incredible Body: Amazing Anatomy Just for KidsWinner of a Parents’ Choice Silver Honor Award. 

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Topics: teach kids anatomy