Welcome to the Visible Body Blog!

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.

anterior-cruciate-ligament-torn-ACL-knee-joint

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.

Temporomandibular-joint-disorder-TMJ-joint-capsule-sphenomandibular-ligament

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.

Ankle-ligaments-talofibular-calcaneofibular-sprained-ankle

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.

Plantar-ligament-plantar-fasciitis-foot-lower-limb

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.

Shoulder-girdle-acromioclavicular-ligament-appendicular-skeleton

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.



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


Further reading:

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.

Liver-Accessory-Organs-Digestive-Anatomy

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:

Liver-Function-Digestive-Anatomy

 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.

Liver-Lobes-Digestive-System-Accessory-Organs

Inferior-anterior view

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


Liver-Lobes-Cuadate-Quadrate-Digestive-Accessory-Organ

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.

Liver-Segments-Couninaud-Classification-Digestive-Accesory

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. 

Liver-Gallbladder-Gall-Bile-Duct-Accessory-Organ-Digestive

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

Diabetes

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

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. 

 

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


Related content:

- Functions of the Liver: http://www.ib.bioninja.com.au/options/option-h-further-human-2/h4-functions-of-the-liver.html
- The Digestive System: http://bit.ly/1x4g8D7
- Interact with the liver and gallbladder with Human Anatomy Atlas

 

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

My-Incredible-Body-Systemic-Arteries-Veins-Vasculature-Kids-Anatomy

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

My-Incredible-Body-Inner-ear-cochlea-kids-anatomy

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

My-Incredible-Body-Eyeball-Pupil-Cilliary-Muscles-Kids-Anatomy

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

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. 

Skeleton-Anatomy-Skull-Calvaria-Cranium-braincase

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.

Skeleton-Anatomy-Skull-foramina-foramen-meatus

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.

Skeleton-Anatomy-axial-ligaments-temporomandibular-joint-skull

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.



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

Related content:
How the nerucarnium develops: http://www.ncbi.nlm.nih.gov/pubmed/7051266
TMJ (Tempromandibular Joint Disorders):http://www.nidcr.nih.gov/oralhealth/topics/tmj/tmjdisorders.htm
Landmarks and foramina of the human skeleton are in the Visible Body app, Skeleton Premium: http://www.visiblebody.com/skeletal_download_overview/

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.

science-puberty-app-for-kids-image-of-egg-and-sperm 

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.

 

science-puberty-app-for-kids-image-of-period-ovary

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.

 

science-puberty-app-for-kids-image-of-pharynx-voice-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.

 

science-puberty-app-for-kids-image-of-acne

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.

 

science-puberty-app-for-kids-image-of-body-odor-sweat

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. 

My Incredible Body is available for

iPhone/iPad: http://bit.ly/1sJebtp
Android: http://bit.ly/1sWW1Rh
Windows Touch: http://bit.ly/win8_mib

Learn more!

Topics: teach kids anatomy

Anatomy and Physiology: Parts of a Human Cell

Posted by Courtney Smith on Thu, Sep 04, 2014 @ 09:53 AM

I remember being in Mr. Farnsworth’s 7th grade science class when we first really began learning about cells. His room looked like the typical high school lab—high, hard tables with Bunsen burners and gas jets that no one was allowed to touch, and a cabinet full of dead things suspended in fluid in jars. My favorite thing about the room was the giant poster of the Triangulum Galaxy (I was, am, and always will be irrevocably fascinated by outer space) on the wall behind his desk. 

But my second favorite thing was the poster depicting the inside of a cell. It hung on the far right wall, next to the chalkboard. While the image of Triangulum was exponentially smaller than the actual galaxy so we could see it in its entirety, the image of the cell was exponentially larger for the same reason. The cell was its own world—but instead of stars, gases, and dark matter, there was mitochondria, a nucleus, and cytoplasm. What that said to me was that, when you got right down to it, there wasn’t a whole lot of difference between a cell and a galaxy.

My 7th grade mind = blown.

Cells are amazing, little things, and I do mean little—cells are tiny. Under the right conditions, you might be able to see an amoeba proteus or a paramecium. To get a better sense of cell size, the Genetic Science Learning Center of the University of Utah has a fun, interactive scale. Prepare to be amazed.

There are two types of cells: prokaryotes and eukaryotes. Eukaryotes contain a nucleus and prokaryotes do not. You, dear reader, are a eukaryotic being. You are made up of trillions of eukaryotic cells, of which there are over 200 different types. Each eukaryotic cell type specializes to perform certain functions. Bone cells, for example, form and regenerate bones. Ever fracture a bone? Within days, cells called fibroblasts begin to lay down bone matrix.

Cells can be divided into four groups: somatic, gamete, germ, and stem. Somatic cells are all the cells in the body that aren’t sex cells, like blood cells, neurons, and osteocytes. Gametes are sex cells that join together during sexual reproduction. Germ cells produce gametes. Stem cells (you may be very familiar with this term because it’s always making headlines) are like blank-slate cells that can differentiate into specialized cells and replicate.

The genetic information within each cell acts as a sort of instruction manual, telling a cell how to function and replicate.

Why don’t we take a look at the inside of a typical cell?

 

Typical Eukaryotic Cell

Eukaryotic cell plasma membrane cytoplasm organelles

The plasma membrane is exactly what it sounds like: a membrane made of plasma. Membranes are structures that separate things; in this case, the plasma membrane of a cell separates its interior from the environment around the cell. It’s not impenetrable, however, as it will selectively let certain molecules enter and exit.

Organelles are the structures within the plasma membrane. Each organelle has a specialized function. They’re called organelles because they act as a cell’s organs.

Intracellular fluid, or cytosol, is the liquid found inside a cell. While most of its makeup is water, the rest isn’t very well understood. Once thought to be a simple solution of molecules, it’s organized on a multitude of levels.

Eukaryotic cell nucleus nucleolus plasma membrane cytosol

The nucleus is a large organelle that contains the cell’s genetic information. Most cells have only one nucleus, but some have more than one, and others—like mature red blood cells—don’t have one at all. Within the nucleus is a spherical body known as the nucleolus, which contains clusters of protein, DNA, and RNA. The genetic information of the cell is encoded in the DNA. The nucleus serves to contain the DNA and transcribe RNA, which exits via pores in the nuclear membrane.

 

Presenting: The Organelles

While all the parts of a cell are important, here are some of the most recognizable.

 

Endoplasmic Reticulum

Besides being very fun to say, endoplasmic reticulum (ER) is a network of membrane-enclosed sacs in a cell that package and transport materials for cellular growth and other functions. There are two types of ER: smooth and rough.

Eukaryotic cell rough endoplasmic reticulum smooth golgi complex apparatus

 

Golgi Complex/Apparatus

Like the ER, the Golgi complex (or apparatus) is an organelle that packages proteins and lipids into vesicles to be transported.

Eukaryotic cell golgi complex apparatus endoplasmic

 

Mitochondria

“A human being is a whole world to a mitochondrion, just the way our planet is to us. But we’re much more dependent on our mitochondria than the earth is on us. The earth could get along perfectly well without people, but if anything happened to our mitochondria, we’d die.” —A Wind in the Door by Madeleine L’Engle (1973)

Eukaryotic cell mitochondria atp power plant energy

While Ms. L’Engle’s concept of mitochondria was more fiction than science (as far as I know, mitochondria don’t talk!), it opened my ten-year-old eyes to the wonders of our bodies. Before Mr. Farnsworth’s cell poster, there was the Time Trilogy.

Mitochondria can number anywhere in the hundreds to the thousands, depending on the cell. They are known as the “power plant” of the cell, providing the main source of energy. Through aerobic respiration, mitochondria generate most of the cell’s adenosine triphosphate (ATP). Active cells in the muscles, liver, and kidneys have a large number of mitochondria to support high metabolic demands.

 

Ribosomes

Eukaryotic cell ribosomes lysosomes organelles golgi complex

Either floating freely in the cytosol, bound to the ER, or located at the outer surface of the nuclear membrane, ribosomes are plentiful within a cell. Ribosomes contain more than 50 proteins and a high content of ribosomal RNA. Their primary function is to synthesize proteins, which are then used by organelles within the cell, by the plasma membrane, or even by structures outside the cell.

 

Lysosomes

Eukaryotic cell lysosomes ribosomes organelles nucleus

These little guys are like the garbage disposals of a cell. Lysosomes contain acid hydrolase enzymes, which break down and digest macromolecules, old cell parts, and microorganisms. They originate by budding off of the Golgi complex.

 

There are more structures and functions within a cell (like, a lot more) than are listed here, but that’s a post for another day!

 

Want to learn more?

All the images and most of the content in this post was taken from Anatomy & Physiology, available for iPad, Android tablet, PC, Mac, and Windows Touch.

Want to go further? Download any of our free A&P eBooks, available now at the A&P eBook Library! Click below.


Learn more about Anatomy & Physiology



Related Posts

- Anatomy and Physiology: Medical Suffixes
- Anatomy and Physiology: Anatomical Position and Directional Terms
- Anatomy and Physiology: Five Cool Facts about the Middle and Inner Ear

Topics: anatomy and physiology, cells

Zybright Guest Blog: Teaching Anatomy with My Incredible Body

Posted by Maite Suarez-Rivas on Fri, Aug 29, 2014 @ 01:39 PM

This story comes to us from a parent, who wrote in to tell us how his daughter’s curiosity about anatomy was born after a fun science lesson at school—then furthered by our app, My Incredible Body (an app filled with tons of interactive 3D anatomy, and dozens of anatomy questions and answers)!

---

One day last winter, “Mr. Bones” visited a grade school classroom in Portland, Oregon. The human skeleton model was brought in by a group of parents who run a chiropractic clinic and wanted to make science learning fun for kids. The students learned how bones support the body and facilitate movement. One of the students, Lily, came home utterly hooked on anatomy.

Science App for Kids Image of Kidneys

In his quest to feed her curiosity, Lily’s dad Sean downloaded My Incredible Body. Off she went, like a little explorer, through the various organs and body systems presented in the app. Sean was nice enough to share with us how Lily uses our kids' anatomy app to learn and create her own science activities.
 

What are Lily’s favorite parts of the app?

She was so excited about the digestive system section that she showed me and wanted to make sure I knew how pee and poop were made. 
 

How else can you tell that My Incredible Body is making an impression on her?

Right now, the section on kidneys is her favorite. The kidney section is so detailed and interesting that Lily drew and cut out a pair of paper kidneys. I was blown away. I mean, I know she is smart, but really—kidney cutouts?!

kids anatomy education science biology

The lovely Lily with her paper kidneys.


Then she video-chatted with her teenage cousins, explained to them how a bite of pizza travels through the body, and used the app to show them where the kidneys and bladder are located in the body. It was hilarious! Her cousins are 16 and 19 and they were awestruck.
 

How would you describe the look and feel of the app?

I think the design is great. The UI remains constant throughout the sections, which is helpful for me. The graphics are detailed and the dialogue has a great way of being technical but also telling a fun story.

 

Is the user experience at the right level for Lily?

The app uses language that is both technically accurate and fun—not too much, but enough to keep Lily’s attention. It treats kids like they have the ability to understand something as complex as the heart and lungs but keeps the communication light.

My daughter is 5 and of course I think she is brilliant, but I believe she is also interested in what most 5 year olds are interested in: pee, poop, and farts are kind of a conversation piece—at least at home.

Digestive system kids anatomy education resized 600

How does Lily like to show what she’s learned?

Lily brings up what she’s learned in the app at places like the zoo or the children’s museum. She knows what the small and large intestines look like and are used for, and she enjoys asking people how long their small intestine is or if they know they have two kidneys.

At the zoo, she wants to know if animals make pee and poop the same way as us.

Lily’s knowledge of the digestive system kind of freaks me out; she understands the entire lifecycle of food and she can explain it to other adults and kids. She is curious how it works in animals and insects as well. My Incredible Body has generated a lot of discussion—and a lot of laughs.

_________________________________________________

Want an app with interactive educational science content? Try My Incredible Body. It’s got answers to kids’ questions about the bodyWhy do I pee? When I touch something hot, how does my brain know it? How often do I blink my eyes? How many teeth do I have?—and so much more!


App Store Badge Google Play Button WINDOWS STORE black

Special thanks to Steve (and Lily!) for allowing us to post this.

Topics: teach kids anatomy

Learn Muscle Anatomy: Bursae

Posted by Courtney Smith on Wed, Jul 30, 2014 @ 08:27 AM

The other day, I let my ten-year old niece play with Muscle Premium on my phone (while I watched cartoons). She kept making the model spin—around and around and around, like a ballerina, until she abandoned it for the muscle actions.

"Auntie," she said, and then didn't follow up with anything, completely engrossed in Elbow Flexion. When I prompted her, she looked up at me and whispered, as if confessing a secret, "Is it supposed to hurt?"

I asked her what she meant. She pointed to the moving model.

"Do bones rub against each other like that all the time? Because I feel like it should hurt."

I watched the animation for a bit—the olecranon of the ulna slid against the humerus's olecranon fossa, back and forth, flexed in a continuous loop. It did look a bit like they were rubbing together. Actually, if there wasn't something there acting as a cushion, moving the joints would be incredibly painful. Luckily, we're not that bad off.

"It doesn't hurt," I began, settling back to finish The Legend of Korra, "Because you have little pillows called bursae inside you that stop your bones from rubbing like that."

She turned her attention back to the TV and waited until the end of the episode to ask more. (My niece is polite like that.)

That was an actual exchange between me and my niece Em, who has an affinity for all things science and interesting. She's awesome.

Anyway, what I told her was the truth: bursae prevent our bones and muscles, particularly in the joints, from rubbing together and creating painful friction. Imagine trying to bend your knee without something to cushion the movement. Talk about ouch, right?

Muscle patella superficial subcutaneous prepatellar bursa knee synovial resized 600 

See those purple lumps in the picture? Those are bursae. They live between bones and bones, or bones and muscles, or muscles and skin, serving to prevent friction at points of stress throughout the body. In the picture, you can see the bursae are either prominently displayed (on top of the patella) or partially hidden between bone and muscle. Think of how often you move and bend your knees—I'm doing it right now, and I'm just sitting! It would be a much more painful action without the bursae there to cushion things.

Bursae come in three packages: synovial, subcutaneous, and adventitious. 

 

THREE TYPES OF BURSAE

Most of the bursae in the body are synovial: thin-walled sacs interposed between bones, muscles, and tendons. The lining of a bursa contains a capillary layer of synovial fluid, which provides two lubricated surfaces that enable freedom of movement. Synovial bursae tend to be located in your joints, like your knees, feet, and shoulders.

 Muscle bursae shoulder joint subacromial bursa synovial resized 600

 

There are also adventitious, or accidental, bursae. These occur in soft tissue over bony prominences, usually because of repeated pressure or shearing.

An example of an adventitious bursae is a bunion, which is a deformity of the big toe. Wearing ill-fitting shoes can sometimes force the big toe inward towards the other toes. The bursa at the metatarsophalangeal joint becomes swollen, but the biggest issue is the normal part of the head of the first metatarsal bone is tilting sideways and sticks out at its top. This creates a large bump or prominence.

 Muscle metatarsophalangeal bursa hallux big toe joint metatarsal resized 600

Subcutaneous bursae lie between the skin and a bony process, like the aforementioned olecranon of the elbow.

Muscle olecranon subcutaneous bursa elbow joint resized 600  

BURSITIS

You've probably spent enough time on this blog to know what the suffix –itis means, so you won't be surprised when I say that bursitis is the inflammation of a bursa. When the bursae become inflamed, their gliding ability is lost, which can be painful. An inflamed bursa is usually the result of trauma, overuse, or infection. Even something as simple as lifting something heavy can bring it on.

The joints of the hips, elbows, and shoulders are normally the areas affected by bursitis, but it can occur anywhere (inflammation of the bursae in the knee is known as Washmaid's Knee).

 

 

WANT TO LEARN MORE?


Related Posts

Learn Muscle Anatomy: Muscles of Mastication

Learn Muscle Anatomy: Knee Joint Group

Learn Muscle Anatomy: Gastrocnemius

Topics: learn muscle anatomy, 3D skeletal system

Zybright Guest Post: 5 Things To Know about the Heart and Blood Vessels

Posted by Courtney Smith on Fri, Jul 25, 2014 @ 12:45 PM

Zybright, Visible Body's sister company, is the maker of My Incredible Body, a best-selling anatomy app for kids and a Parents’ Choice Silver Honor Award Winner. We're giving them the floor for another guest blog post, because they're awesome and we adore them.

Take it away, Zybright!

++++++++++++++++++++++++++

If you have our app, all this content comes from the Circulation Tour section. If you don't, get the free trial! You can download it to your iPad/iPhoneAndroid, or Windows 8.1 device. 

5 things to know about the heart and blood vessels

1. Your heart is a hollow muscle that has four chambers filled with blood. Think of these chambers as rooms. When your heart beats, two of those chambers—the ventricles—squeeze, which shoots blood where it needs to go. Your right ventricle sends blood to the lungs to pump it full of oxygen, and your left ventricle sends that oxygen-rich blood to the rest of your body.


2. If your heart chambers are rooms, then your heart valves (highlighted below) are doors. They open to allow blood to go in and out, but shut to prevent it from backtracking.

My incredible body heart valves semilunar tricuspid mitral anatomy resized 600

Fun Fact: If the valves don't close completely, blood could leak backward. The heart would have to work even harder to make sure blood was getting to where it needed to go.
 

3. The atria (highlighted below) are temporary holding tanks for blood. Your left atrium holds the blood that's coming from your lungs, while your right atrium holds the blood that is returning from the rest of your body.

My incredible body heart atrium atria anatomy resized 600

4. Systemic veins and arteries are spread throughout your entire body and act like roadways for your blood. Systemic arteries send oxygen-rich blood from your heart to your organs and tissues, which gives them oxygen in order to function. Systemic veins take blood that has lost its oxygen back to the heart, where it will be sent to the lungs for a refuel.

Fun Fact: The aorta is the largest artery in your body and is roughly the size of a garden hose!
 

5. The pulmonary vessels (branching structures in the image below) in the lungs work a little differently than the systemic vessels—in that they work the opposite way! The pulmonary arteries carry blood that needs to be refueled with oxygen to the lungs, while the pulmonary veins carry freshly-fueled, oxygen-rich blood back to the heart.

 

My incredible body heart pulmonary arteries veins lungs anatomy resized 600

Fun Fact: Pulmonary comes from the Latin word pulmonarius, meaning "of the lungs." 

 

++++++++++++++++++++++++

Did you and your kids enjoy these facts? Then keep busy with these free 30-minute activities!

Access the My Incredible Body 
Freebies Library

 

Topics: teach kids anatomy