The Skeletal System ( ESSAY )

Though your bones look all dry and austere, don't be fooled, they are actually alive. Bones are considered organs themselves because they contain more than one type of tissue. They are actually as dynamic as any of your organs is, and they are constantly repairing and you basically get a brand new skeleton in 7 to 10 years. They're job is way more than just providing you with support but also to :

• produce blood cells
• store energy as fat
• storage for calcium, phosphate, and other mineral.
• regulating blood calcium levels
• producing hormones osteocalcin
• protects against glucose intolerance and diabetes

So you see, they are basically another one of your organs. An average human body contains 206 bones, ranging in shape and size, from the tiny stapes in your ear, to the huge femur that makes up the entire length of your thigh. Autonomist often divide those bones into 2 categories :

• axial
• appendicular

Your axial bones is the bones that are found in your bodies vertical axis, like the skull, well basically all the bones that protect your other organs, ahhhh how heroic.... While your appendicular bones are, well, everything else. From there, your bones are generally classified further by their shape :

• Long Bones, the classic "dog-bone" style
• cube shaped Short Bones
• Flat Bones, the thin bones like the one that cover your brain
• Irregular Bones, the odd-shaped looking bones, like your vertebrae and pelvis

But despite their variations in size and shape, all bones have a similar internal structure. They all have a smooth, dense external layer of compact, or cortical bone around a porous, honeycomb-looking area of spongy bone. The spongy bone area is where typically you would find your bone marrow, which are found in two colors, red and yellow. The red bone marrow are responsible for creating blood cells, while the yellow bone marrow are the storage for your fat. The arrangements of these bone tissues, though, can be a little different from each other. Like in your flat bone, the spongy bone is in between the cortical bone, while in the long bones, the spongy bones are only found in the tip of the bones, called epiphyses. The basic unit of bones are called osteons. They are cylindrical, weight-bearing structures that run parallel to the bones axis. Look inside one, and you will see them look like tube inside of a tube. Each one of these tubes, called lamellae, is filled with collagen fibers. Now the tube that are in the tube, is filled with nerves and blood vessels. So there you go. A tour of an organ that you have known all your live, without you realizing it to being an organ, like a ninja, eh?

Vision ( ESSAY )

Nearly 70% of all the sensory receptors of your whole body are in the eyes, so it's important to "see" what's going on and what does our eye looks like, right? But the fascinating thing about our eye doesn't end there. In order for you to see, perceive, or recognize anything, nearly half of your entire cerebral cortex has to get involved. Vision is considered the dominant sense of humans, and while we can get along without it, and it can be tricked, what you are about to learn is NOT an illusion.
When I talk about your sense of hearing, I started with the mechanics of sound, and now is not going to be any different. Light is electromagnetic radiation travelling in waves. Remember how the pitch and loudness of a sound is determined by the frequency and amplitude of it's waves? Well, it's similar with light, except that the frequency of a light wave determines the hue, while the amplitude of the light wave determines its brightness. We register short waves at high frequency as bluish color, while long, low frequencies look reddish to us. Meanwhile that red would look dull and muted at low amplitude, while if the amplitude are high it would look bright to us. But the visible light we are able to see are only a tiny chunk of the whole electromagnetic spectrum, ranging from super tiny gamma rays, to super long radio waves. Some of the first things that you will notice if you look at an average pair of eyes, are all the outer things that are created to help protect your eyes from the outside world : the eyebrows, that help keep your sweat away from your eyes; the super-sensitive eyelashes, that trigger reflexive blinking; your eyelids; the tear-producing lacrimal apparatus. The eyeball itself are irregularly spherical, with an adult diameter of about 2.5 centimeters. It's essentially hollow, full of fluids that help keep it's shape, and you can only see about the anterior sixth of the whole ball. The rest of it is safely tucked into a pocket of protective fat, tethered down by six strap-like extrinsic eye muscles, and jammed into the bony orbit of your skull. Your eye's wall is made up of three distinct layers : the fibrous, vascular, and inner layers. The outermost fibrous layer is made of connective tissue. Most of it is that white stuff called the sclera, while the most anterior part is the transparent cornea. The cornea is like the window that lets light in. Going little deeper, there's the posterior choroid, the one that supply all the layers with blood. In the interior, there is also the ciliary body, a ring of muscle tissue that surrounds the lens, but off course the most famous part of the vascular layer is the iris, which is that distinctive colored part of the eye that makes your eye different from anybody else in the world's eye. The pupil is an opening in the iris that let's light in. The opening in the iris is controlled by sphincter muscles, that control how much light gets into your eyes. Light comes in through the cornea and pupil and hits the lens, the transparent, convex disc that focuses that light and projects it onto the retina, which makes up the inner layer at the back of the eyeball. The retina itself has two layers, the outer pigmented layer that helps absorb light so it doesn't scatter around in the eye, and also the inner neural layer.

Hearing and Balance ( ESSAY )

Let's start today with several questions.

• What is sound?
• How can I hear the sound?
• How can I walk around without falling on my face?

I'll start off by answering the first question. The basic and short answer to the question of "what is sound" is : 'Sounds create vibrations in the air that beat against the eardrum, which pushes on a series of tiny bones called "auditory ossicles" that move internal fluid against a membrane that triggers tiny hair cells -- which aren't actually hairs -- that stimulate neurons, which in turn send action potentials to the brain, which interpret them as sound.' Short and simple, right? But there is a lot more going on in our ear to just allowing us to hear a beautiful song, it also allows you to stand up, walk, and even dance. Yes, the ear also houses the part of your body that allows you to keep your balance. To better understand how your ears pick up sound, we must first understand how sound actually works. The key to sound transmission is vibration. When I talk, my vocal folds vibrate, creating sound. When I slam this desk I'm writing on, or strum a guitar, those vibrations cause air particles to vibrate too, initiating sound waves that carry the vibrations through the air. To hear a sound, your ear must then pick up that vibration that was travelling through the air, and then send it to your brain that then process it, then, and only then, can you finally hear the sounds. One more thing. You may say, "well they all vibrate, what then makes their sound different?" The difference is in the shape of the sound waves and their frequency. Frequency is the number of waves that pass a certain point at a given time frame. A high-pitched noise is the result of shorter waves moving in and out more quickly, while fewer, slower fluctuations, result in a lower pitch. That is for how high or low the notes are, but for loudness, it depends on the waves' amplitude, or the difference between the high and low pressures created in the air by that sound wave. Now, in order for you to pick up and identify barking or beeping, or any sound at all, the sound waves have to reach the part of the ear where those frequencies and air-pressure fluctuations can register and be understand by the brain. Now let's get to the anatomy of the ear. The ear are divided into three major areas : the external, middle, and inner ear. The external and middle ear are only involved in hearing, but your inner ear is key to both hearing and maintaining your balance, or equilibrium. So the pinna, or auricle, is the part that you can see, and wiggle, or grab, or festoon with an earing. It's made up of elastic cartilage covered in skin, and it's main function is to catch sound waves, and pass them along deeper into the ear. Once a sound is "caught" it is funneled down into the external acoustic meatus, or auditory canal, and toward your middle and inner ear. Sound waves traveling down the auditory canal eventually collide with the tympanic membrane, which you probably better known as the eardrum. This ultra-sensitive, translucent, and slightly cone shaped membrane of connective tissue is the boundary between the external and middle ear. When those sound waves collide with the eardrum, they push it back and forth, making it vibrate so it can pass those vibrations along to the tiny bones located in the middle ear. Now the middle ear, also known as the tympanic cavity, is the relay station between the external and inner ear. It's main job is to amplify things a little bit, so that they are louder when they enter the inner ear. And it needs to amplify those sound waves, because the inner ear is located inside a special fluid, and as you probably already know, that it is more hard to move through a liquid than through a vacuum. The tympanic cavity focuses the pressure of sound waves so that they're strong enough to move the fluid in the inner ear. And it does this by the help of the auditory ossicles -- a trio of the smallest bones in your whole body : the malleus, incus, and stapes, commonly known as the hammer, anvil, and stirrup. One end of the malleus connects to the inner eardrum and moves back and forth when the drum vibrates. The other end is attached to the incus, which is also connected to the stapes. Together they form a kind of chain that conducts eardrum vibrations over to another membrane, the superior oval window, where they set those fluid in the inner ear into motion. Your inner ear is mysterious, complicated, and also interesting. It has some of the most complicated anatomy of your entire body, and don't worry, it is planted deep down in your head, so it's more or less, safe. It's other name : the labyrinth. It has two very important jobs to do : to turn those vibrations into electrical impulses that the brain can understand; and also help maintain your balance, or equilibrium, so that you are always aware which way is up or down and stuff. The labyrinth actually has two layers : the bony labyrinth, and the membranous labyrinth. The bony labyrinth is a big fluid-filled system of wavy wormholes. while the membranous labyrinth is a continuous series of sacs and ducts inside the bony labyrinth that basically follow the bony labyrinth's shape. Now the hearing function of the inner ear is housed in the cochlea, which has a back-of-a-snail-like structure. But the maintaining-your-equilibrium stuff is housed in the vestibular apparatus. Inside the vestibular apparatus, there is fluid that is controlled by the movement of your head. This structure has three semi-circles which all sit in the sagittal, frontal, and transverse planes. Based on the movement of the fluid inside of them, those three semicircular arches can detect movement of your head from vertically, horizontally, and in between those. So there you go. An essay on your ear, hearing, and how you can keep your balance, or equilibrium.

Lynx ( ESSAY )

A lynx, is any of the four species within the Lynx genus of medium-sized, short tailed, with tufts of black hair on the tip of their ears, a large and padded paws for walking on snow and long whiskers on their face. Under their neck, they have a ruff which has black bars resembling a bow tie although most times, this characteristic is not visible. Neither the caracal, sometimes called the desert lynx, nor the jungle cat, called the jungle lynx, is a member of the Lynx genus. Here are the scientific classification of the lynx that I have found :

•  Kingdom: Animalia
•  Phylum: Chordata
•  Class: Mammalia
•  Order: Carnivora
•  Suborder: Feliformia
•  Family: Felidae
• Subfamily: Felinae
• Genus: Lynx

There are four living species of the Lynx genus, the Eurasian Lynx, Canada Lynx, Iberian Lynx, and the Bobcat, and they are all believed to have been evolved from the Issoire Lynx that was believed to lived in Europe and Africa during the late Pliocene to the early Pleistocene. Out of the four living descendants of the Issoire Lynx, the Eurasian Lynx is the largest in size. They are native to the European and Siberian forests. The Eurasian Lynx is the third largest predator in Europe, next to the Brown Bear, and the Grey Wolf. It is a strict carnivore, consuming only about one to two kilograms of meat every day. The Canada Lynx or the Canadian Lynx, is a North American felid that ranges in forest and tundra regions across Canada and into Alaska. The Canada Lynx is also a good climber and swimmer. The Iberian Lynx is an endangered species native to the Iberian Peninsula in Southern Europe. It is the most endangered species of cat in the whole wide world. According to the Portuguese conservation group SOS Lynx, if the Iberian Lynx became extinct, it will be the first feline extinction since the Smilodon 10,000 years ago. The bobcat is a famous North American wild cat. With 12 recognized subspecies, it is common throughout Southern Canada, the continental United States, and northern Mexico.   

Taste & Smell ( ESSAY )

Now we are going to started diving into our "world of senses". How we experience our six major senses all boils down to one thing : "sensory cells translating chemical, electromagnetic, and mechanical stimuli into the "language" of our nervous system, which is action potentials". The process that changes chemical, electromagnetic, and mechanical stimuli into action potentials is called "transduction" and every organ of our body each have a different way to do it. Our vision functions with the help of photoreceptors, cells that detect light wave, while our senses of touch, hearing, and balance uses mechanoreceptors that detect sound waves and pressure on your skin. But our sense of taste or gustation, and smell or olfaction, works by sensing mechanical senses. They call on the help of chemoreceptors on our nose and mouth to interpret that stimuli into action potentials. The thought of our senses is just 5 or 6 are wrong. We actually have tons of secondary senses, like the ability to sense temperature, pain, acceleration, etc. That is all considered senses. Our most primitive and fundamental are our sense of taste and smell. Believe it or not, the sense of taste and smell are most strong at birth. As we get older, those two senses "decline", so the older we are, the less "good" our sense of smell and taste is. Tastes and smell are also powerful at activating memories, triggering emotions, and alerting us to danger. Now lets start to analyze how you can detect chemicals in the air and then turn them into the thoughts of "hmmm nice smelling pizza". All process starts as you and I sniff the molecules (or chemicals) of, lets say pizza. That means that the molecules are floating in the air, and that also means that the molecules are in a gaseous form, or volatile. And yes, when you smell poop, there is actually poop particles in your nose right there and then. Those pizza molecules that are floating in the air are vacuumed up your nose. Most of these is filtered out by your nose hair but not all of them. A few make it all the way to the back of the nose and hit your olfactory epithelium. This is your olfactory system's main organs. But here's the wonder of our sense of smell : Each olfactory neuron has receptors to detect a single kind of smell. At any given thing, like the pizza that you are smelling, there are hundreds of chemicals, like the thymol of the oregano, the butyric acid of the cheese, and much more. All the receptors that are "turned on" by the chemicals in the air, sends a signal to the brain, then the brain combined that all and tell you that, wow this is a very delicious smelling pizza. Scientist estimate that our 40 million different olfactory receptors neurons helps us identify about 10.000 different smell, maybe even more. Now just imagine a piano with thousands of keys able to produce millions of different combinations of sounds, you'll get an idea of how amazing our sense of smell are. So once the smell of pizza hit the olfactory neuron, it sends it to your brain through the olfactory tract to the olfactory cortex of the brain. From there, the pizza-smell hits the brain through two avenues : One brings the information to the frontal lobe, where they can be consciously identified, like oh, the smell of pizza; while the other pathway heads straight to your emotional ground control -- the hypothalamus, amygdala, and other parts of your limbic system. This emotional pathway is quick, intense, and fast to trigger memories. If the odor is associated to danger, like the smell of smoke, it quickly activates your sympathetic nervous system's "flight of fight" response. And these same intellectual and emotional apply to taste as well. Because taste is basically 80 percent smell. That's why when you couldn't smell, you usually also couldn't taste. As you chew your food, air is forced up your nasal passages, so your olfactory receptor cells are registering information at the same time your taste receptors are, so you are basically tasting and smelling at the same time. So, it's true when you caught a bad cold, or just hold your tongue so that air couldn't pass through your nose, you could still taste some food, but it would not be the same. So you can hold your nose and taste that something is sweet, but you could not pinpoint that it is caramelized sugar or just plain old sugar. Most of your taste buds are located on your tongue, but some is also located on your cheeks and other places on your mouth. As soon as you take a bite, all of the sensory information is quickly sorted by the ten thousand or so taste buds located on your tongue, mouth, and upper throat. Oh yeah, by the way, the taste maps of your tongue, that you probably have seen, are wrong. Those tongue diagrams date back to the early 1900s, when German scientist D.P Hanig tried to measure the sensitivity of different areas of your tongue for sweet, salty, sour, and bitter. The map that are resulted are pretty subjective, pretty much just reflecting on what his volunteers felt like they were sensing. While it's true that taste can be grouped into sweet, salty, bitter, and sour, all your taste buds, wherever they are can still taste all of those tastes. A little experiment. Try putting salt on the tip of your tongue, where the taste map tells us that that region is for tasting sweet, you would still taste the salt in all it's glorious saltiness.


P.S. : I mostly gathered the information to create this post from Crash Course. If you don't know 'em, check out their youtube channel, it's awesome, I'll promise you that. 

Parasympathetic Nervous System ( ESSAY )

Consider your heart for a moment. For the average person at rest, like you probably are, sitting in front of your computer, reading from my blog, the heart beats at around 60 beats/minute. One beat per second. Nice and easy..... But if you were somehow be able to disconnect your heart from your autonomic nervous system, you will certainly guessed that things will change. But, your heart will not stop. Actually, it will be the opposite. Your heart rate will speed up. It will start to beat at around 100 beats/minute, 2/3 faster, and that is just at rest, without you breaking a single sweat. But your cardiac muscle would experience a lot of "wear and tear". The surrounding blood pressure would be under enormous pressure, and your body will suddenly require - and waste - a lot of energy. Basically your homeostasis - the name for when your body is in balance - would be ruined. Partly, the job of the parasympathetic nervous system is to keep your heart under homeostasis, or in balance. It's often described as the calming side, the mellow side of your autonomic nervous system, a kind of antidote to the effects of stress created by your sympathetic nervous system. But it's job is really much more than that. Unlike your sympathetic division, which deals with the "crisis of now", which is not a movie, by the way, the parasympathetic division deals with, well, everything else. It not only calms you down after being stressed out, but also it allows you to digest food, to reproduce, to excrete waste, to fight off infection, well everything other than becoming stressed, all the things you need to do to, well, be a living thing and live. But our bodies can only do that when they are in balance, somewhere between excitement and inhibition, both aroused enough but also calm enough, then your body can do the business of living. Our sympathetic and parasympathetic nervous system differ not only by their functions, but also by their positions and the positions of their ganglia. The sympathetic ganglia are located near the spinal cord, while the parasympathetic ganglia are found way out, or even in the effector organs. Likewise, the use of neurotransmitter in the two system are similar, but not exactly the same. In both system, the neurons release acetylcholine, in the preganglionic cell, which is the cell that comes before the ganglia. But the difference here is what comes after the acetylcholine crosses the ganglia. In the parasympathetic division, what comes out of the ganglia is still acetylcholine, while what comes out of the sympathetic division is norepinephrine. But, the biggest anatomical difference between these two system has to do with the physical networks that they form as they reach to every part of your body. The network of your sympathetic division -- I'm getting tired of spelling s-y-m-p-a-t-h-e-t-I-c and p-a-r-a-s-y-m-p-a-t-h-e-t-I-c all the time -- is found in the thoracolumbar area of your spinal cord. While the parasympathetic division are craniosacral, meaning they sprout from the bottom of your brain and just superior to your tailbone, and most of these nerves never go through your spinal cord.
Most of you will think that the two divisions of your autonomic nervous system as opposites or rivals, but that is a little off the mark. Looking at your body as a whole, you should picture them as two side of a scale. Sometimes your body tips a little to one side, and sometimes your body tips to the other side. The balance depends on having the right amount of both. The rate of action potentials travelling through your sympathetic division is known as your "sympathetic tone" and the tone travelling through your parasympathetic system is "parasympathetic tone". And most of the time, your parasympathetic tone is actually dominant, something I'm very glad to know.

Sympathetic Nervous System ( ESSAY )

So you're sound asleep, dreaming away, when suddenly the smoke alarm goes off. Before you even know it, you started to feel it, all the smoke and stuff. Those smoke alarms are loud - for a good reason. Your heart starts to race, your breathing picks up, you become sweaty all over your body. You are stressed. And I'm not talking about my-iPhone-is-about-to-die stress. I'm talking about maybe-I-am-going-to-die stress. Even though stress is often viewed as a dirty word, it, just like pain, isn't all bad, it's actually very useful if you're, y'know, trying to get off of a burning building and stuff. Your sympathetic nervous system is the part of your system responsible for stress, and it does it's job exceedingly well by focusing on what your body needs to do right now. Like if you are in a burning building. What you need to do is to run out of the building ASAP, not digesting the McDonald that you just eaten. That is stuff that you can deal later, when you are out of the life-threatening situation. So your sympathetic nervous system sweeps these suddenly trivial functions aside and focusing your blood and energy to the thing that needs to be done like, right now. So, pity on the guy that his sympathetic nervous system doesn't work well. But here is the problem: nowadays our bodies' stress responses are getting triggered all the time, even when you are not on a life-threatening situation, and that's not good. When you are stressed, you are basically overdriving your whole body, and that's a good thing if you are facing life-or-death ordeal. But if you are not, well, your body can get tired by being on overdrive for too long, and, well, "stressed". Like if you are late to an important meeting, but still stuck in a traffic jam, that kind of situation doesn't need your body being run on overdrive, but good luck explaining that to your nervous system. Because your physiological responses to non-immediate stress are largely the same as when you are fighting to stay alive. So that is why stress is sometimes - maybe most times, bad for you. Now I will tell about how your sympathetic nervous system takes over your body for several minutes. The stress signals includes two chemical : neurotransmitters and hormones. Neurotransmitters are made by and released by neurons themselves. While hormones are secreted by your glands. There are at least 50 different hormones in work in your body right now, and they do everything from regulating your sleep cycle, to making you retain water, so you don't get dehydrated. The understanding of neurotransmitters and hormones are 100% necessary for understanding how your sympathetic nervous system ultimately works. BUT! When you are trying to trace a single sympathetic signal, from the initial stimulus to the final response, that is a tough job, because the very same substances can have different effects, actually, sometimes, totally different effects depending solely on where it's being received in your body. And, fun fact, a compound can be considered both a hormone or a neurotransmitter without it changing a single bit, depending on where it is operating in your body. I know this is confusing, but bear with me. Ok, time to dive in. You are waken up by the smoke alarm. You need to move. Fast. Your brain sends action potentials down your spinal cord and preganglionic neuronal axons - I know, fancy words. Those signals flows all the way to their ganglia. When the signal reach the synapses inside the ganglia, the nerve fibers inside the ganglia then release a neurotransmitter, called acetylcholine, known to it's friend as ACh. In addition to working in sympathetic ganglia like this one, it's also what the rest of your peripheral nervous system and lots of your central nervous system uses to communicate. So when it comes to nervous communication, the ACh is basically the coin of the realm. The "Hermes" of your body. So the ACh crosses that synapse, and if there is enough of it, it can stimulate action potentials in several neurons at the other end. That's all it does. But it is important. It's basically a signal booster. Those actions potentials are then carried to the effector organs, in this case, let's say, your leg muscles, which are going to need an influx of blood if they are going to hustle you out of that house. And at the end of that second, the postganglionic neuron releases a different neurotransmitter. This one is called norepinephrine. It's what crosses that final synapse, and creates a response in the effector, like opening your blood vessel, so blood can flow more freely, providing your leg muscle the blood and oxygen it needed. So basically, the norepinephrine is the guy that "do" stuff, while the acetylcholine is, maybe kinda like the postman. Now the way the neurotransmitter/hormone like norepinephrine works, is a good example of another confusing aspect of your sympathetic nervous system. Because it works by both stimulating and inhibiting the same systems in your body at the same time. Like if you are in a life-or-death situation, norepinephrine your system releases causes an increase of blood flow in some parts of your body, and inhibiting blood to not flow to certain parts of your body where it's not needed right now, like to your stomach. That all depends on the organs. Several organs, like your stomach, have certain receptor that when triggered, will "prohibit" that organ. So it all depends also on what kind of receptor is getting triggered. Next, we will talk about the mellow-part of your autonomic nervous system, the one that tells you that it is now all right, the parasympathetic nervous system, so stay tuned.

Autonomic Nervous System ( ESSAY )

Your autonomic nervous system is the branch of your peripheral nervous system that regulates the functions of your internal organs, like your stomach, liver, and heart. It also controls your smooth and cardiac muscles, and your glands. All things that you do not consciously control, so yeah, you could say it has a lot of power over you. But thanks to it, you wouldn't need to command your brain to breath, to breath, the autonomic nervous system lifts that burden off of you. But the confusing thing about this system is that it's effect on your organs, muscle, and glands is by no means consistent. At any given moment, your autonomic nervous system is constantly making involuntary, fine-tuned adjustments to your body, based on the signals received by your central nervous system. This could mean changing your body temperature, or changing by what rate your heart is pumping blood. It's effects change, depending on the situation you're in, and also which part of your autonomic nervous system is in charge at that particular moment. Because this system that keeps you alive is actually run by TWO competing interests. Two divisions that serve the same organs, but they create different effects on them, one calming it down, while the other are making it more excited. The one that is dedicated to prepare you for activity, is the Sympathetic Nervous System, and the one that relaxes your organs is the Parasympathetic Nervous System. Together, they are what makes your body experience stress, fear, defiance, relaxation. So if there are an adventure novel, full of love, hatred, and tears that is being written in your body, it's probably being written by these two - the sympathetic nervous system and the parasympathetic nervous system.
Let's talk a sec about names. Contrary to it's comforting name, the sympathetic nervous system is what sounds your internal organs' alarm bells, therefore making your organs excited. It's the hardware behind the "fight or flight" response. Now the parasympathetic is for "resting and digesting", the opposite of the sympathetic system. It's responsible for conserving energy for later and maintaining your body. One more proof that you shouldn't judge or think about someone from their names or looks. Even though their basic components are basically the same, their physical structures are different in very important ways. Here are a list of those key differences which we'll be discussing later :

• Relative lengths of their fibers
• Location of their ganglia
• Sites of origins of neurons from the central nervous system

And those three chief differences can help explain why they act like the foils that they are. Foils, by the way is like contrasts, contrasts of each other.

P.S. : I mostly gathered the information to create this post from Crash Course. If you don't know 'em, check out their youtube channel, it's awesome, I'll promise you that.

   

Peripheral Nervous System ( ESSAY )

When it comes to the nervous system, or just your body in general, let's face it; the brain get's all the praise. And it deserves those praise. It's a complicated, amazing, and awesome piece of God's work. But the brain, even with all it's "amazingness", would be pretty useless without a support team that kept it connected to the outside world. Without a constant flood of external information that the brain can process, the brain starts to confuse it's own thoughts for actual experiences, and many other abnormalities. So it really needs that support team. And when talking about that support team, the peripheral nervous system is the one who came up for the job. Our peripheral nervous system keeps our brain in contact with the outside world and allowing it to respond to those information. This networks snakes to just about every part of our body. When you look at a human body "transparently", the peripheral nervous system is those tiny little "strings" that is everywhere and runs everywhere in your body. It provides the central nervous system with information, ranging from temperature, to the touch on your shoulder, or a twisted ankle. The sensory nerve receptors spy on the outside world for the central nervous system, and each type responds to different kinds of stimuli. They allow the central nervous system to communicate and feel the outside world. Here are a list of sensory nerve receptors that you and I have, and their functions :

• Thermoreceptors : respond to changes in temperature
• Photoreceptors : react to light
• Chemoreceptors : pay attention to chemicals
• Mechanoreceptors : respond to pressure, touch, and vibration.

We also have specialized nerve receptors called Nociceptors, that fire only to indicate pain. Most people go to great lengths to avoid pain, but pain is really an incredibly useful sensation, because it helps protect us from ourselves, and the outside world. It also help us to better protect ourselves from life-threatening situations. If you're feeling physical pain, it probably means that your body is under stress, damaged, or in danger, and your nervous system is sending a cease and desist signal, that tells you to back away from bonfires, or to not step on a needle, or to seek medical attention, like, RIGHT NOW!! Pain is a pretty subjective feeling, but the fact is, we all have the same pain threshold. That is the point where a stimulus is strong enough to reach a certain threshold. But you and I might have different tolerances for pain and discomfort. It's not our toughness that makes us more tolerance to pain, but the "tolerance" itself is the thing that makes you and I different in responding to pain. Just like my mom and dad. My dad can eat a plate of noodles, still putting of steam, and not burning his tongue in the process, but my mom can't. Instead, my mom has a higher tolerance rate in tasting cold stuff. My dad, say, can eat 10 scopes of ice cream before he get brain freeze, but my mom can eat 15 scopes of ice cream before getting the dreaded brain freeze. So the pain tolerance is different, but the pain threshold is the same in all of us. So in that way, pain is actually good for us, and that is why pain exists in the first place. Most doctors think of pain, as the perception of pain, whatever your brain is telling you what pain is. I'm not saying you should enjoy and try to be in pain until you can't no longer endure it....that would be stupid. All I'm saying is that you should realized that pain is one of God's many creative and brilliant ways to protect you, or you to protect yourselves.

P.S. : I mostly gathered the information to create this post from Crash Course. If you don't know 'em, check out their youtube channel, it's awesome, I'll promise you that.

Pistol Shrimp ( ESSAY )

Alpheidae, most commonly known as pistol shrimp or alpheid shrimp, is a family of caridean snapping shrimp, characterized by having asymmetrical claws, the biggest of them all can produce a loud snapping sound, which is either for scaring predator, killing prey, or to battle against their own species. Most snapping shrimp dig burrows, and are common inhabitants of coral reefs, submerged sea grass flats, and oyster reefs. Their family is diverse, and the population is distributed worldwide, consisting of about 600 species within 38 or more genera. Their scientific classification is:

•  Kingdom: Animalia
•  Phylum: Arthropoda
•  Subphylum: Crustacea
•  Class: Malacostraca
•  Order: Decapoda
•  Infraorder: Caridea
•  Superfamily: Alpheoidea
•  Family: Alpheidae

The snapping shrimp can grow to about 1-2 inches ( 3-5 cm long ). It is distinctive for the large claw, that can reach to more than half the length of it's already small body. The claw can be on either arm of the body. Unlike most shrimps, it lacks the pincers. But it do have a pistol-like feature made of two parts, one part can open up to about a 90 degree angle. Then to shoot, it slams the two parts together to create a enormous, powerful, super-hot bubble. Believe it or not, the bubble can reach temperatures up to about 4000 degrees C. That's almost as hot as the sun's temperature!!! The snapping shrimp also competes with the beluga whale and the sperm whale for title of the loudest animal in the sea. The pistol shrimp's "pistol" can reach up to 218 decibels. Think about it. An animal 1-2 inches long competing with an animal 18 feet long for having the loudest noise in the sea. That just blows my mind away.....

Central Nervous System ( ESSAY )

I hope you remember that our nervous system is divided into two main networks that work together to help you talk, think, and even move around : the central nervous system, which we'll be talking today, and the peripheral nervous system. The central nervous system consists of two main parts, the brain and the spinal cord. The central nervous system's main task is to :

• integrate sensory information that the peripheral nervous system collects from all over our body
• coordinating both conscious and unconscious activity

All of your sensations, thoughts, and directions are processed through this two-part system.

Our brain's job is to :

• sorts out all sensory information
• give orders
• carries out our most complex functions like thinking, feeling, and remembering.

Meanwhile, the job of our spinal cord is to :

• conducts two-way signals between your brain and the rest of your body
• governing basic muscle reflexes and patterns

So, the spinal cord has some authority over something, other than just carry out signals from the brain to the rest of the body and from the rest of your body to the brain as I previously expected. Both our brain and spinal cord are made of fragile, jelly-like nervous tissue that is extremely susceptible to injuries. So all that "goo" is well-protected by the bones of your vertebrae and cranium, as well as membrane layers, or meninges, before being bathed in a cushy waterbed of clear cerebrospinal fluid. This fluid actually allows our brain to somewhat float in our skull, reducing it's weight in the process. But even with all that extra protection your skull and other "stuff" that protects your brain, it is still pretty vulnerable to injuries. That injury can come from outside of your body, or from inside, like in the case of some sort of virus attacking your brain. Your brain is divided into specialized regions, that may or may not interact with each other to produce a given action. So, let's say that a virus attack and damaged, say, the part of your brain that is in control of giving you the ability to understand and talk understandable language, then you will not be able to talk or understand anyone's speech, because the part of the brain controlling that is damaged. So you see that the brain is still pretty vulnerable, so we need to do our part to protect our brain and spinal cord. God has given us the protection necessary, like the skull, but we must also protect our brain and spinal cord the best we can.

P.S. : I mostly gathered the information to create this post from Crash Course. If you don't know 'em, check out their youtube channel, they are amazing.

Nervous System ( ESSAY )

The nervous system is the system that processed and executed all your thoughts, actions, and your particular way of making a sandwich. It received stimuli from your skin, your eyes, your taste buds on your tongue and processed them so you can feel that it is a thorn you are holding in your hand, that the building you see are grey and cool looking, and that the food you are eating are very bitter. The nervous system are like the headquarters of your body. And like most of the stuff that is in science, it too is divided into subgroups, the central and peripheral nervous system. The job of the nervous system as a whole is : Sensory Input, Integration, and Motor Output. Let's talk about an example to further understand this three main jobs of the nervous system. Let's say that you are sunbathing on your big backyard, when suddenly a spider walk on your foot. The feeling you feel of those eight, tiny, little legs is the first of the three main jobs the nervous system do for you, the sensory input part. From there, the nervous system process that information, and then decide what should be done about it. That's the integration part. So if you do anything that you are ashamed of when your friend joke you by putting a fake spider on your lunchbox, you should blame your nervous system about it. Then, maybe your leg just shoot of and kick that spider halfway across the country, then you are in the third part of the nervous system's job, the motor output. It's commands your muscles to do something. So whatever little thing you do, thank the nervous system for it, and, most importantly, thank the Creator of such ingenious system. Now let's talk about the separate parts of the nervous system. The central nervous system consists of your brain and spinal cord, the main control center. The peripheral nervous system is, well the rest of the group, which is composed of all the nerves that branch of from the brain and spinal cord to the rest of your body and it's job is to bring the orders from your brain and spinal cord to your muscles, to do the order. And since it's job is for communication, the peripheral nervous system is set up to work in both direction, sending information to your brain, and also to receive the orders sent back by the brain. So that's the organization of your nervous system in a nutshell. If you want to know more about the individual parts of the nervous system, check out my next post - if it has been posted yet.

P.S. : I mostly gathered the information to create this post from Crash Course. If you don't know 'em, check out their youtube channel, it's awesome, I'll promise you that.

Tissues ( ESSAY )

Our whole body are made of cells. About 7 octillion of them, to be precise. And every cells in your whole body, every single one of those 7 octillion cells, have a specific job, to keep the homeostasis going on in you body. Homeostasis, by the way, is a balance of materials and energy to keeps us alive. Back to the cell. Now every cell has a different job, but those jobs sometimes are very identical. Like, if a cells job is to "put garbage on garbage bin", and another cells job is to "pick up garbage from the ground", those job are very similar, and cells that have very similar jobs group together to form "tissues" that form a common function or goal to achieve homeostasis to keep you alive. FINALLY were in the part where we talk about the heading of this essay... Anyway, tissues themselves have different functions. Four different functions to be precise:

• Nervous Tissue "Control and communication"
• Muscle Tissue "Movement"
• Epithelial Tissue "Cover and protect your body"
• Connective Tissue "Provide support"

Nervous tissue control your communication and control. Nervous tissue forms the nervous system. Our nervous tissue has two big functions: to sense stimuli and to send electrical impulses through the body, often in response to the stimuli. This tissue are also made up of two different cell types: neuron and glial cells. Neurons are the specialized building blocks of the nervous system, they're what generates and conduct the electrochemical nerve impulses that let you think, dream, or do anything. They are also all over your body. When you touch a fuzzy dog, or a cold metal, or hot water, the neurons in your skin's nervous tissue send stimuli to your brain - not someone else's brain - that sense that stimuli and then you can feel the world around you, like fuzziness, coldness, or the unwelcoming feeling when you dip your hand in boiling water. No matter where they are, the neuron has a same anatomy, consisting of the cell body, dendrites, and the axon. The cell body, also called soma, is the "headquarters", containing a nucleus, mitochondria, and DNA. The dendrites, look like the root of the trees they're named after, and they're job is to collect the stimuli and information from other cells. They're the listening end. The long rope-like axon is the transmission cable - they carry messages to other neurons, and muscle, and glands, and stuff. The other type of nervous cell, the glial cells, are like the neurons pit crew, providing support, insulation, protection, and tethering the neuron cell to the blood vessels.
But your whole body would be utterly helpless if there are nothing or nobody that can do the commands the neurons send, which is why we have muscle tissues. Unlike our nervous tissue, the muscle tissue can contract and move. Muscle tissue also are well-vascularized, meaning it got a lot of blood coming and going, and it comes in three 'flavors', skeletal, cardiac, and smooth. Skeletal muscle tissue are found in our bone. This is the only one of the three that we can control. The other ones all work involuntarily, which is great, so we don't have to think to breath. The cardiac muscle tissue forms the walls of our heart, and works involuntarily. This tissue is only found in our heart. And finally we have the smooth muscle tissue, which lines the walls of most of your blood vessels and hollow organs.
Now we can finally talk about the epithelial tissue, which is the most awesomely named muscle tissue for me. The epithelial tissue is great at separating other cells from each other. It's like a burly gym teacher that knows what to do to keep his students in order. The epithelial tissue creates order where otherwise there would be total chaos and mayhem. Because we, humans, are filled with complex, fidgety, feisty systems that need to be separated to some extend if we want our different parts to achieve anything.
Now we will reach the most abundant and diverse of the four tissue type, the connective tissue. This is the stuff that keeps you -and me- looking young, makes up the skeleton, and delivers oxygen and nutrients throughout our body. It's what holds you, and me, together, in more ways than one. Connective tissue is pretty much every in our body, but the amount of how much is found in different parts of the body vary from organ to organ. For instance, the skin is made of mostly connective tissue, while the brain has very little, since it's almost all nervous tissue. There are four major classes of connective tissue: Proper, cartilage, bone, and most surprisingly, blood. Here are a list of what our connective tissue does to keep our homeostasis on play: Binding and supporting; protecting; insulating; storing reserve fluid and energy; transporting substances within our body; and also for movement. There is no other tissue that can boast of such high diversity as the connective tissue. But if there is so much diversity how can we group all these "diversityness" into one tissue group??? Well there are three factors that all the "branches" of the connective tissue have in common and the one that make them special : First, they share a common origin. They all form from mesenchyme, a loose and fluid type of embryonic tissue, which makes "vested" on them the ability to move oneself, which all other tissue type don't have. They also have different degrees of vascularity, or blood flow. Finally, and as strange as it may sound, all connective tissue are mostly composed of nonliving material called the extracellular matrix.

P.S. : I mostly gathered the information to create this post from Crash Course. If you don't know 'em, check out their youtube channel, they are amazing.