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Serious as a Heart Attack: 7 Facts about Cardiovascular Disease

Posted by Courtney Smith on Fri, May 22, 2015 @ 02:47 PM

When you see a heart attack in a movie or TV show, it’s usually a dramatic event—clawed hands clutching a chest, groaning, and then a twisting fall to the floor. Which… well. Take that with a grain of salt. A heart attack is caused by a blockage, usually a build-up of plaque, in an artery that prevents blood flow and oxygen from reaching the heart. The longer the heart doesn't receive blood, the greater the damage to it. In many cases, people don’t even know they’re having a heart attack.

But despite what Hollywood tells you, a heart attack doesn’t exist in a vacuum—it’s the result of a bigger problem: heart disease. Even with a large presence in our society, not many people know the cold hard facts about heart disease, so I'm here to lay them down for you.



7 Facts about Cardiovascular Disease


1. Many people might think cancer is the number one cause of death for both men and women in the United States, but it in fact is number two, right behind heart disease. Heart disease is the cause of 611,000 deaths every year in the United States—that's 1 in every 4 deaths.


2. More than 735,000 people suffer a myocardial infarction (MI)—that’s the official name of for heart attack—every year in the United States. Of those people, 15% (110,250) of them will die from it.


3. Every 34 seconds, someone in the United States suffers a heart attack.


4. While most people know that chest pain is a sign of a heart attack (thanks, Hollywood), it's not the only one. Shortness of breath, fatigue, dizziness, nausea, and pain or discomfort in the back, jaw, neck, and arms are all possible indicators of MI.


5. It's a no-brainer that high cholesterol and blood pressure are contributing factors to heart disease, but additional factors include smoking, diabetes, and not getting enough exercise.


6. Since 1984, more women than men have died from heart disease, but only 1 in 5 women knows that heart disease is the greatest threat to her health. 38% of women die within a year of having a heart attack as compared to 19% of men.


7. According to the World Health Organization, childhood obesity has reached epidemic proportions. Obese children are at a significant risk for heart disease in their adult lives, as well as diabetes, atherosclerosis (build-up of fats and cholesterol in the artery walls), and high blood pressure.


Don’t let heart disease be the thing that does you in, my dear readers. Go out in a blaze of glory, maybe in an incident involving a jet pack or a giraffe herd. Take care of yourselves—I want y’all around for a long time!

Like what you read in this blog? Then go a step further:

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Related Posts:

Anatomy & Physiology: The Anatomy of Vision
Anatomy & Physiology: Parts of a Human Cell
The Endocrine System: Hypothalamus and Pituitary 


-   Know the Signs and Symptoms of a Heart Attack. (2015, April 30). Retrieved May 22, 2015, from CDC.gov

-  Leading Causes of Death. (2015, February 6). Retrieved May 22, 2015, from CDC.gov

Childhood obesity and cardiovascular disease.Tracey Bridger. Paediatr Child Health. 2009 March; 14(3): 177–182.

Heart Disease Facts. (n.d.). Retrieved May 22, 2015, from The Heart Foundation

Facts about Heart Disease in Women. (n.d.). Retrieved May 22, 2015, from Illinois Department of Public Health

Topics: learn heart anatomy

The Lymphatic System: Innate and Adaptive Immunity

Posted by Professor Blythe Nilson on Mon, May 11, 2015 @ 02:20 PM

Today’s post is coming all the way from Canada’s western-most province. Blythe Nilson, Associate Professor in the Biology Department at the University of British Columbia—Okanagan campus, is about to school y’all in the lymphatic system. So pop some vitamin C, kick back, and read on.

Take it away, Professor!


The Lymphatic System

First, let’s quickly review the lymphatic system. The lymphatic system carries out the body’s immune responses by producing and distributing cells, such as lymphocytes and macrophages, that combat disease.

Lymph vessels, or lymphatics, drain fluid from all parts of the body and return it to the heart. They begin as narrow blind-ended vessels in tissues then merge with others as they travel toward the vena cavae, where they return the lymph into the circulatory system. Unlike the blood vessels, lymphatics are one-way.


The spleen is a soft, delicate organ that filters blood for pathogens, debris, or worn-out cells. The spleen is made up of compartments called follicles that are filled with lymphocytes and macrophages that can mount an immune response quickly if antigens are detected. The spleen destroys and recycles about 200 billion worn-out red blood cells every day.


The thymus is a soft, bilobed organ that lies between the heart and the sternum. It’s larger in young people because developing T-lymphocytes spend time there as they mature. Only competent T-cells are allowed to leave the thymus, which destroys any faulty ones. After puberty, the thymus is no longer needed; it atrophies and the lymphatic tissue is replaced by fatty tissue.

Lymph nodes are small, roundish organs that form along lymph vessels. As lymph passes from a lymph vessel through a node it slows down and percolates through millions of lymphocytes and macrophages. If a pathogen is detected the immune cells will multiply, causing the lymph node to swell.



Innate Immunity

As you may know, the body has several structures that serve as protective barriers against infection. These include the skin, respiratory and digestive tract mucous membranes, and other structures.

The term immunity refers to the many structures and responses the human body has for preventing pathogens from entering the body and for fighting them off if they do get in.

Immunity can be broadly divided into two categories: innate immunity and adaptive immunity. Innate immunity is the body’s general response to invading pathogens—it’s the same in everyone and reacts the same way each time. Essentially, we are born with innate immunity all ready to go.

Innate immunity includes physical barriers, such as the skin, and chemical responses, such as antimicrobials found in tears. It also includes physiological responses, such as fever and inflammation. These processes stimulate immune cells to take action, hinder pathogen growth, and prepare damaged tissues for repair. Specialized cells, like macrophages, can kill and digest bacteria and parasites, as well as secrete cytokines that can induce inflammation and mobilize other parts of the immune system.


An inflammatory response causes blood vessels to dilate, bringing more blood to the site and causing localized heat. The vessels also become leaky, allowing fluid and immune cells to leave the bloodstream and enter the infected tissue. The cardinal signs of inflammation are swelling, redness, and heat, and often there is pain and loss of function.


Adaptive Immunity

Now let’s have a look at the other arm of the immune system: adaptive immunity.

Adaptive immunity is the body’s way of mounting an immune response that is specific for each pathogen. B- and T-lymphocytes, or B- and T-cells are central to adaptive immunity. They are able to recognize each kind of invading pathogen and respond with a large, focused response tailored to that specific invader. What’s more, each time a new pathogen is found, the lymphocytes that recognized it will multiply and remain in your body so that if that pathogen ever returns, your immune response will be swift and massive.


Antibody-mediated immunity is triggered when  your B-cells recognize a pathogen. Of the trillions of B-cells in your body there are some with receptors specialized to recognize every pathogen you are likely to encounter. When a subset of B-cells is activated they produce antibodies, specialized proteins that are released into blood and tissues where they bind to pathogens, marking them for destruction by macrophages and other immune cells.

Cell-mediated immunity is carried out by T-cells when they recognize pathogens living inside your cells. Infected body cells display pieces of the pathogen on their surface that are recognized by T-cells. This activates the T-cells, causing them to recruit other cells of the immune system that will deal with the invaders, often by killing the infected cell!


Want to learn more?

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Related Posts:

Anatomy & Physiology: The Anatomy of Vision
Anatomy & Physiology: Parts of a Human Cell
The Endocrine System: Hypothalamus and Pituitary 


Special thanks to Professor Nilson for contributing to the Visible Body Blog!

Topics: anatomy and physiology

Anatomy & Physiology: The Limbic System's Major Three

Posted by Courtney Smith on Fri, Mar 27, 2015 @ 02:25 PM

What is your earliest memory?

Mine is the sound of my older brother Steve muttering, "I don't know why you're laughing, we're going to get in trouble," and the rush of sand as he helped me pour a bucketful over my head. We were at my Yiayia's house in her sun-soaked backyard, sitting in the little turtle sandbox that was missing an eye (courtesy of my cousin Billy, I would learn years later while going through pictures). The bed of wildflowers nearby kept catching on Steve's shirt and smelled earthy-sweet. While the adults lounged about on the back deck, toasting my mother for keeping her too-curious child alive long enough to see a second birthday, Steve helplessly held the now empty yellow bucket in his hand while I cackled triumphantly to myself.

Sometimes when I'm lounging in my Yiayia's backyard (now hanging with the adults), I'll smell the wildflowers and bam. Suddenly I'm two years old again with sand in my hair and so very proud of the fact.

Long-term memory is still a mystery in a lot of ways, but we do know that the limbic system has a hand in processing and consolidating it. That's not all the limbic system does, however, and we're going to take a look at the role three of its major components play in the brain.


A Functional Classification:
The Limbic System Is, Well, a System

When one speaks aloud about the limbic system, it sounds as though they consider it to be a single structure. That's simply not true. While there’s some debate in the scientific community about which structures are part of the limbic system, there's a unanimous agreement about three of them: the amygdala, hippocampus, and cingulate gyrus. In addition, there’s also the dentate gyrus, parahippocampal gyrus, fornix, and other nuclei and septa.


The limbic system functions to facilitate memory storage and retrieval, establish emotional states, and link the conscious, intellectual functions of the cerebral cortex with the unconscious, autonomic functions of the brain stem.

While the sensory cortex, motor cortex, and association areas of the cerebral cortex allow you to perform certain tasks, the limbic system makes you want to do those tasks. It's your very own internal motivational speaker!


Amygdala: The (Not Actually) Missing Link

Amygdala is a fun thing to say, yes? Ah-meg-dala. It sounds like a city in Game of Thrones.

While small, the amygdala has the big job of acting as the link between a stimulus and how you react to that stimulus. By receiving processed information from the general senses (your eyes, your skin, your tongue, etc.), it’s able to mediate the proper emotional responses. For example, I'm allergic to chocolate, so smelling it invokes a response of disgust in me. For others, it would invoke a kinder response. In my friend's case, it would send her into a euphoria.


Output from the amygdala goes either to the hypothalamus or the prefrontal cortex. Output going to the hypothalamus influences visceral and somatic motor systems. Through these connections, an emotional response to something might make your hair stand on end, make your heart race, or even induce vomiting! Output going to the prefrontal cortex involves conscious responses, such as telling someone you love them or controlling your anger.  


Hippocampus: Memory Consolidator

Hippocampus sounds like something straight out of myth—which it is. In Greek mythology, the hippocamp(us) was a creature with the top half of a horse and the bottom half of a long, scaly eel or fish. Chances are, there was one swimming around the Great Lake at Hogwarts.

The actual anatomical structure is named for its resemblance to the curved tail of the seahorse-like creature. The hippocampus is found in the medial temporal lobe and consists mostly of gray matter. Not very pretty for a memory-forming center, all things considered.


Memories aren’t stored in the hippocampus, but rather cognitive and sensory experiences are organized into a unified, long-term memory. When you experience something, like touching something hot for the very first time, the hippocampus learns the sensory input in relation to the experience and then plays the memory back repeatedly to the cerebral cortex to form a long-term memory in a process called memory consolidation. Think of it as the hippocampus' way of teaching the cerebral cortex. Memory consolidation continues until a long-term memory is formed, which will be held in one of the various areas of the cortex (different memories are housed in different areas).


Cingulate Gyrus: The Limbic Big Boy

I love the cingulate gyri—they look like something Professor X would wear to help him look for new mutants. While it isn't known whether they can enhance one's telepathic ability to locate others with superhuman abilities, the cingulate gyri are known for other things that are just as cool (okay, maybe not).

Ever been so excited about something that your arms flail around, or so angry that your hands clench into fists? The cingulate gyrus, a large arch-shaped structure, plays a role in expressing emotions through gestures.


A gyrus is a convolution, or fold, in the brain that acts to increase surface area, which in turn increases the number of neurons, as well as gray matter. There are many gyri that interact with the limbic system and the brain as a whole. The precentral gyrus (posteriormost gyrus of the frontal lobe) contains the primary motor cortex and controls the precise movements of skeletal muscles. The postcentral gyrus (anteriormost gyrus of the parietal lobe) contains the primary somatosensory cortex and is responsible for spatial discrimination (recognizing the part of your body that’s being stimulated).


Like what you read in this blog? Then go a step further:

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Related Posts:

Anatomy & Physiology: The Anatomy of Vision
Anatomy & Physiology: Parts of a Human Cell
The Endocrine System: Hypothalamus and Pituitary 


Topics: anatomy and physiology

No dry-erase boards: An ER doctor discusses using our anatomy reference with his patients

Posted by Lori Levans on Mon, Mar 09, 2015 @ 11:16 AM

Meet Dr. Brennen Beatty. He’s an ER physician in Austin, TX.

In recent months, he’s changed the way he talks to patients about their diagnosis. The old way was to tell them what was going on and hope they understood what he was talking about. The new way? Show and tell them using Visible Body’s Human Anatomy Atlas, a visual anatomy reference.

When did you start using Human Anatomy Atlas?

I started using Visible Body’s Atlas on my iPhone just recently—and I’ve kicked myself for not using it earlier. I use Atlas to quickly help patients visualize and understand their diagnosis. This technology helps me improve patient experience, compliance with treatment plans, and my overall efficiency.

Do you find that most of your patients understand their own anatomy?

Not exactly. One out of five Americans are seen every year in the ER and the bulk of patients don’t understand their own anatomy and physiology. To help them understand, patients want to see something. We’re visual animals.

How do they react when you use Atlas?

When I show Atlas on my iPhone my patients become wide-eyed with understanding.


What did you do to help illustrate a point before using Atlas?

Previously I found myself constantly using the dry-erase board in the ER to draw crude anatomy. Or if there was a rolling laptop cart in the room, I’d Google an image. If a patient presented with vertigo and dizziness, for example, I’d call up a picture of the inner ear to explain that connection.


Your overall verdict?

With Atlas, I’m using modern, advanced technology to quickly help my patients visualize and understand their diagnosis. Plus, the learning curve is straight up; it’s easy to use.


Want to see how Dr. Beatty explains gallstones to a patient using Human Anatomy Atlas 7?



Topics: anatomy and physiology

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.


Like what you read in this blog? Then go a step further:

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Related Posts

The Anatomy of Vision
Parts of a Human Cell
5 Cool Facts about the Middle and Inner Ear

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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