When it comes to the nervous system, or just your body in general, let’s face it: your brain gets all the props. And it deserves those props! It’s a complicated, and crucial, and sometimes crazy boss of an organ. But your brain would be pretty useless without a support team that kept it connected to the outside world. Because frankly, like any leader, the more isolated your brain gets, the weirder it gets. Put a person in a watery, pitchblack sensory deprivation tank, and you’ll see the brain do some really weird stuff. Without a constant flood of external information, the brain starts.
To confuse its own thoughts for actual experiences, leading you to hallucinate the taste of cheeseburgers, or the sound of a choir singing, or the sight of pink stampeding elephants. It’s your peripheral nervous system that keeps things real, by putting your brain in touch with the physical environment around you, and allowing it to respond. This network snakes through just about every part of your body, providing the central nervous system with information ranging from the temperature, to the touch of a hand on your shoulder, to a twisted ankle. The peripheral nervous system’s sensory nerve receptors spy on the world for the central nervous system, and each type responds to different kinds of stimuli.
Thermoreceptors respond to changes in temperature. photoreceptors react to light, chemoreceptors pay attention to chemicals, and mechanoreceptors respond to pressure, touch, and vibration. And then we’ve got specialized nerve receptors called nociceptors that, unlike those other receptors, fire only to indicate pain, which is the main thing I want to talk about today. Because, as unpleasant as a stick in the eye or tack in the foot may be, pain is actually a great example of where everything we’ve talked about over the last few weeks all comes together, as we trace a pain signal through your nervous system, from the first cuss to the Hello Kitty band aid. By the end of this episode of Crash Course Anatomy Physiology you’ll never think.
Of a stubbed toe, pounding headache, or burned tongue the same way again. Most people go to great lengths to avoid pain, but really, it’s an incredibly useful sensation, because it helps protect us from ourselves, and from the outside world. 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 to stop twisting your arm like that, or to back away from that bonfire, or please seek medical attention, like, RIGHT NOW. So in that way, pain is actually good for you that’s why it exists. I’m not saying it’s pleasant, but if you’ve ever wished for an XMenlike power to be impervious to.
Pain, I’ve gotta say, that is one foolish monkey’s paw of a wish. Just ask Ashlyn Blocker. She’s got a genetic mutation that’s given her a total insensitivity to any kind of pain. And as a result, she’s absentmindedly dunked her hands in pots of boiling water, run around for days without noticing broken bones, and nearly chewed off her own tongue. Luckily, such congenital conditions are very rare. The rest of us have a whole nervous system dedicated to making sure our bodies react with a predictable chain of events at the first sign of damage. Like say you just wake up and you’re extraordinarily hungry for some reason, so you run downstairs to grab some clam chowder, but you didn’t put any shoes on and suddenly you’re like, â€œYOWW!â€�.
There’s a tack, fell out of the wall, and you stepped right on it of course. Your foot immediately lifts off the ground, and then you’re assuring your dog that you’re not yelling at her, you’re just yelling, and then you limp over to the couch, and sit down, and you pull up your foot, and remove that spiny devil from your flesh. You want to talk physiology? So what exactly just happened in your body? Well, the first step was a change in your environment that is, a stimulus that activated some of your sensory receptors. In this case, it was a change from the probably completely ignored feeling of bare skin on.
A smooth floor to a distinct feeling of discomfort the sharp metal tack piercing your skin. Your peripheral nervous system’s mechano and nociceptors provided that base sensation, or awareness that something had changed. Then it went to your central nervous system first to the spinal cord that caused the immediate reflexive action of pulling up your foot, and then your brain eventually interpreted that awareness into the perception of pain, and decided to pull the tack out and probably say an expletive or two. Pain itself is a pretty subjective feeling, but the fact is, we all have the same pain threshold. That is, the point where a stimulus is intense enough to trigger action potentials in those.
Development of Glaucoma Animation Open Angle vs Angle Closure Glaucoma
Glaucoma is a group of eye diseases in which the optic nerve is damaged leading to irreversible loss of vision. In most cases, this damage is due to an increased pressure within the eye. The eye produces a fluid called aqueous humor which is secreted by the ciliary body into the posterior chamber a space between the iris and the lens. It then flows through the pupil into the anterior chamber between the iris and the cornea. From here, it drains through a spongelike structure located at the base of the iris called the trabecular meshwork and leaves the eye. In a healthy eye, the rate of secretion balances the rate of drainage.
In people with glaucoma, the drainage canal is partially or completely blocked. Fluid builds up in the chambers and this increases pressure within the eye. The pressure drives the lens back and presses on the vitreous body which in turn compresses and damages the blood vessels and nerve fibers running at the back of the eye. These damaged nerve fibers result in patches of vision loss, and if left untreated, may lead to total blindness. There are two main types of glaucoma: openangle and angleclosure. Openangle glaucoma , or chronic glaucoma, is caused by partial blockage of the drainage canal. The angle between the cornea and the iris is quot;openquot;, meaning the entrance to the.
Drain is clear, but the flow of aqueous humor is somewhat slow. The pressure builds up gradually in the eye over a long period of time. Symptoms appear gradually, starting from peripheral vision loss, and may go on unnoticed until the central vision is affected. Progression of glaucoma can be stopped with medical treatments, but part of vision that is already lost can not be restored. This is why it’s very important to detect signs of glaucoma early with regular eye exams. Angleclosure glaucoma, or acute glaucoma, is caused by a sudden and complete blockage of aqueous humor drainage. The pressure within the eye rises rapidly and may lead to total vision loss quickly. Certain anatomical features.
Of the eye such as narrow drainage angle, shallow anterior chamber, thin and droopy iris, make it easier to develop acute glaucoma. Typically, this happens when the pupil is dilated and the lens is stuck to the back of the iris. This prevents the aqueous humor from flowing through the pupil into the anterior chamber. Accumulation of fluid in the posterior chamber presses on the iris causing it to bulge outward and block the drainage angle completely. Acute angleclosure glaucoma is a medical emergency and requires immediate attention.