Stroke

 About 550,000 Humans suffer from this Brain Scorching Disease every year. That means someone suffers from this disease every minute. But  to who why, how, and when does stroke occur? You are just about to find out.

    Stroke is not one disease but has many branches. And each branch has a name based on how it forms. These names include Brain Attacks, cerebrovascular accidents (CVA's), hemorrhagic stroke, etc. But all of these strokes have one thing in common. It is on blood shortage in the Brain. Those who suffer stroke are usually above the age of 55 or so. Stroke in children is extremely rare. Stroke can lead to paralysis, mental, or physical damages in the brain and even to death within a few hours if not treated.

 The most common form of stroke is know as cerebral thrombosis  This is when an artery in the brain is blocked and blood flow stops. An important flow of oxygen and nutrients is cut off by a clot. And because of this, million of cells die instantly. Depending on which part of the brain the blood doesn't reach effects the damage type. 

Cerebral embrosis occurs whenever there is a blood clot elsewhere in the body and that artery leads up to the brain. There also the supply of nutrients and oxygen is cut off.
And many more such as hemorrhages where blood vessels burst open in the brain and and a massive session of blood clots and internal bleeding occur. These occur when a patient has high blood pressure.

    There are many more reasons why stroke forms, one includes atherosclerosis (hardening of the arteries) sickle cell anemia, migraine drug abuse and many more.

    Some symptoms of stroke include dizziness, weakness, lack of consciousness or like what my grandfather faced, vomiting, paralysis on a particular side of the body right/left and a loss of balance and coordination. If you put hot water on his left leg he won’t feel anything, but if you put cold water on the same leg of his, he will feel a painful burning sensation.

Although the large number of 550,000 people who suffer of stroke every year, the death rates and stroke rates have plummeted because of a more sophisticated supply of medicine and education on stroke. Medicines such as t-PA have been introduced dispersing blood clots rapidly within 1-3 hours. But a patient with stroke must consult a doctor immediately, for the amount of damage to the brain increases with every minute left untreated. 


    And now, my grandfather has lost much of his balance and coordination as well as control of some body parts.He is lucky to live and so are many people now thanks to medicines. 

There are many diseases which increase the chance of getting stroke. These include diabetes, blood cholesterol levels, high blood pressure, heart diseases and etc.

But of all the risks, hypertension is the greatest. There are also multiple risk factors for stroke including smoking, which doubles your chances of getting stroke. "It is responsible for a greater percentage of the total number of strokes in young adults than in older adults." (Brain Disorders Sourcebook)

Blood pressure diseases such as hypertension, multiply the chance of you getting stroke by 6x's. An entire 3^rd of the adult population have hypertension, and 40-70 percent of which are senior citizens. The systolic pressure (max blood pressure for the left artery of the heart) should be 120mm and a diastolic (blood pressure between heartbeats) of 80mm is considered normal.

The second most common cause for stroke, is Heart Disease. This is because a faltering vain leading up to the brain, could lead to clotting. Abnormal beating of the left artery is a major heart disease in terms of contribution towards stroke. This is known as atrial fibrillation. This affects 2.2million people in the U.S. alone. 15% of people who have stroke have this condition.

Credits- Brain Disorders Sourcebook- Judd, Sandra

Protection of the brain

The protection of the brain is a vital part of your survival. Although brain functions are important and complicated, safety comes first. Without protection to your brains, they can be penetrated and damage at every step you take while walking. 

The brain is found inside a bone shelter called the cranium. The cranium will protect the brain from concussion and many other injuries. Together, the cranium, cheek bones, jaw bones, teeth and etc. form the skull protecting your whole face from injury. The cranium will provide the tough protection of anything trying to penetrate through the bone. But the cranium is not enough to protect the brain, because every hard hit you take to the head will affect the brain through shocks from the cranium.

This is why we also have 3 other layers known as the meninges. These layers are made up of tissue which cover and blanket the surface area of the brain's cerebral cortex as well as the spinal cord.  The three layers are known as dura mater, archanoid, and pia mater. Let's take a closer look at these. 

The dura mater is made of 2 layers of a white-like, non flexible thin wire called the membrane. The outer layer of the dura mater is called the periosteum  An inner layer called the dura makes the outer most inner part of the skull. The dura and the falx(a minor layer) separate both the left and right hemispheres of the brain. And at the same time the dura and the tentorium separate both top and bottom hemispheres.

The second layer know as the archanoid is a thin, delicate layer and unlike the dura mater, it is very elastic, in fact this stretches to cover the entire brain. This layer carries many blood vessels of many different sizes across its wide range. The archanoid serves as a secondary layer and gives the brain more like a transport system for blood vessels. 

The layer of meninges closest to the surface of the brain is known as the pia mater. This carries many blood vessels from the stretchable archanoid deep into the brain. The pia mater is the one which has a bumpy bottom surface to firmly but gently cradle the brain and keep it in place with the support of the other meninges. There is a gap found between the pia mater and the archanoid known as the subarchanoid space. This is were your cerebrospinal fluid flows(CSF).

CSF is found surrounding the brain and the spinal cord. It is a clear and has a similar viscosity to water. This helps cushion the brain including the spinal cord from any injury. The CSF serves other interesting purposes such as flowing out waste. It also serves as a transportation route to transport hormones around to parts of the brain. When CSF builds too much in ventricles, obstructs ventricles, or has problems without absorbing waste you are diagnosed with the condition of hydrocephalus.

So, imagine what it would be like without brain protection, in fact if you didn't have brain protection you couldn't even imagine! You would be receiving concussions every second. So remember every part of the brain and nervous system plays a vital role in your survival, not just boosted thinking where you wouldn't have anything to loose. Credits: Human Brain Diseases a Sourcebook

Regulation of the Body

    The body's basic functions are carefully controlled in order to keep a stable internal system. And while regulating the body the hypothalamus and brain stem are key to our involuntary internal organs. They play many roles such as co operating with chemical messengers(which are your hormones) to keep the body going. Mostly without your you being conscious!

  Regulation of the Heartbeat
    The heart rate is regulated by the autonomic nervous system (ANS). The sympathetic ANS slows down heartbeat while the parasympathetic is related to activity and speeds it up. 
    
    The head quarters for the ANS heart regulation is not found in the cerebular cortex of the brain's main body but it is located in the brain stem. About half way down the brainstem there is an area called the Medulla. The medulla is the sight also for breathing regulation. Nerves branch down from the medulla to the organs under our rib cages.

     The medulla contains a clump of neurons communicate with the cardioregulatory center. In response to the information, the ANS sends signals to the sinoatrial node and the atrioventricular node in the heart. These nodes then set the heart beat to a speed which is suitable to the amount of oxygen coming into the body.

    The Hypothalamus
     The hypothalamus contains many clumps of neurons called nuclei, these are small clusters. These nuclei control regulations of many things like your, eating, body temperature, hormonal levels, wake/sleep cycles and your balance! The hypothalamus is the main coordinating center and even connects to the ANS. Through all these intricate connections out, the hypothalamus plays a huge responsible part. 
    
    It produces vital responses for your survival. 
Ever wondered why you are hungry? Well, that's your hypothalamus notifying you of the possible consequences of not taking food(nutrition) and brings the pain of acids in your stomach to your consciousness. It also plays a party in emotions such as anger.
So know you know that the hypothalamus is vital to your life and even subtle damage could cause the worse consequences and long term(even permanent) consequences throughout your life.
Credits: The human brain by Rita Carter

Memories

  Memory   (All credits to: The Human Brain – Rita Carter)

Memory is basically a broad term used to represent a number of different brain functions. They are stored in fragments all around the brain. You react towards past memories using the same neurons that created that memory. Memory can be as simple as reciting phrases or recognizing people, walking, or even knowing that the cereal is waiting in the right most cupboards. Different events or phenomena involve learning or the full/ partial reconstruction of the past. 

  When you re-call an experience you recollect (recreate)  it. Recollecting makes the original neurons even more involved in the past experience this makes remembering much easier and then to a point that it simply pops up into your consciousness more frequently. So, repeatedly reconstructing memories makes it easier to recall. For example, lets take something simple like walking. You walk very often, so this memory is for your motor cortex(movement center - see previous posts). This memory is then stored.

  When a memory sparks off, the hippocampus triggers various aspects of it in unison. For example, remembering a pet dog Different areas of the brain recall different things about this dog. Such as feeding the dog, the dog will howl, or even the roughness of its fur. 

Thalamus – Directs Attention

Parietal Lobe – Spatial memories (cognitive, records memories)

Frontal Lobe – Working, processing memory

Cerebellum – Memory and events linked by time

Hippocampus – converts short term memory into long term

Amyglada – Emotional memory is store

Mamillary bodies – episodic memories (memories you can recall)

Temporal Lobe – General knowledge

Declarative memories are facts you can bring to mind consciously. This is processed by the hippocampus.

  Short Term memories will stay until they have no further use, such as a phone number you only use once. Long term memories will be recalled even after years or decades. It will take 2 years at least for a long term memory to form. 

  Working memories are important. Processed in the frontal lobe, it holds a plan of action based on past experiences. This includes calling pieces of memory from all over the brain. Brilliant tacticians have a good working memory.

  Memories from different senses are stored in the limbic system (found in the temporal lobes). This will remind you of the mushy texture of rotten banana or the stench of a dead lizard. Perhaps even the voice and tone that lets you know that your father is angry at you.

  

  

Sense of Smell- Olfaction

    Vision has become the key sense for us humans today. But the sense of smell (olfaction) remains very important to our survival because it will warn us of hazardous substances in the area. Perhaps rotting food.  Other animals such as snakes depend on the sense of smell for many things. Such as the positioning of potential prey.The sense of taste and smell are very closely linked.

    Smell is a chemical sense, like taste. Special receptors in the nasal cavity detect scent molecules. The molecules travel up the nose because of air currents. Sniffing, obviously will take in more molecules giving you a better smell. Olfactory receptors, located at the top of the nasal cavity pick up scent information and send it through electrical impulses to the olfactory bulbs in the limbic system. 

  The Olfactory bulbs are located in the limbic system. They are in control for many things such as emotions, desires and instincts. This is why smell can trigger emotional reactions. Once processed by the Olfactory bulbs your reflex will take place. This is how olfaction occurs.  

Credits: The Human Brain
Author: Rita Carter

Cells in the Brain

Neurons are clearly differentiated by their way to communicate and interact with other cells through electrical and chemical signaling. They come in many different morphologies. This is determined by their tails, nucleus, and branches. Axons are the long  hot dog bun connected body of the Neuron.Dendrites are the branches which come off the end of the axons known as terminals. Dendrites are used for signaling in a process called synapses. Synapses helps convey information from neuron to neuron in a nerve. At the end of each dendrite is a synapse.

  

    This synapse will meet with others from different neurons to continue a message towards or from the Central Nervous System (CNS). Axons are the tails of neurons. On one side of them is the big circle where the neurons and axons exist. On the other side is the axon ending. There are 100 billion neurons existing in the human brain. The amount of information that 1 neuron took in its life time is measured in converge. And the amount of information 1 neuron sent in life is divergence.

    Glial cells out number neurons 3:1. The word Glial comes from the Greek word Glia or glue. This is because the Greeks thought Glial cells hold the nervous system together. Although they have large numbers they do not interact with electrical or chemical signaling or synapses. The purpose of Glial cells is for helping in recovery such as concussions, speeding up signaling, or cleaning wounds, all depending on what Glial cell type they are..

Different types of Glia include

Oligodendrocytes- Only found in the CNS. Lay a layer of lipids called Myelin to speed up electrical signaling and synapses of neurons.

Schwann cells- Only found in PNS also lay Myelin in nerves.

Microglia- Remove debris from injuries in normal cells.

Visual Perception

We do not see what we think we see exactly. When we look at a scene, we only see a few important details unless deliberately drawing attention to other parts of the image.

Visual perception is momentary, partial, and fragmentary. Bottom-up visual processing presets the brain with information about the whole field of vision, but top-down processes select which part of the scene gets our attention. The rest of the image remains a blur unless deliberately drawing attention to it. So, when we look at a picture (just a glance) we only see highlights.


The Brain works very much to make sense of pictures as in visual information.  Looking at complicated scenes activates processes and distinguish target objects. They eye is simply another extention of the brain with over 125 million light sensitive cells. I

There are 4 parts to seeing

1. Movement
2. Depth
3. Form
4. Color

One way to imagine visual perception is to think of an assembly line going throughout a route to make an end product. In the end you get a fully processed image. But in some people there will be less neuron's than average for a certain part of this route which can cause disease such as colorblindness.  

The dorsal route is involved with depth and motion. The dorsal route is responsible for charting the location and position of the object. In the end you get the object position, movement and some of size and shape. This path goes from temporal to frontal lobes.

However in the Ventral route the information flow from frontal to temporal lobes. Involving color and form, the ventral route identifies and sights different objects such as faces. This sight of a face will flow the information from the frontal lobe to the temporal lobe  The temporal lobe which is involved with memory will identify the shape.

Human senses

  The brain uses sense organs to reach out to its environment by which it responds to different stimuli such as light, sound waves, and pressure. This information is then transmitted electrically to different specialized areas of the cerebral cortex where all is processed into senses of hearing, vision, taste, touch, and smell.

  Sensory Neurons react to data from certain sense organs. Visual cortical neurons are highly sensitive to information from the eyes through the optic nerves.  Visuals neurons have been found to be more sensitive and react more strongly towards weak light signals coming from the optic nerve. 

  In most people who are blind or deaf, some some neurons that are usually to do with sight(this is in blindness) are taken over by hearing. Thus making people who cant see hear better and those who cannot hear see better. The primary visual cortex(center) is located in the back of the brain in the occipital lobe. The primary hearing cortex is found in the temporal lobes or the sides of your heads near the ears.

  In Synesthesia, most people are aware of only aware of one sensation in response to to one type of stimuli. For ex. Sound waves make noise but some claim to experience more than one sensation, and they can see sound as well as hear it. They can taste images as well as see them. This is when the neural pathway from a sense organ diverges and carries data from one type of stimuli to a part of the brain where it processes it as another. 

Brain Stem and the Cerebellum

  The brain stem isn't just a part that leads to the brain with  messages but sends messages too. The brain stem includes most of the brain but the cerebrum and diencephalon. Its upper most region is in the mid brain. Just bellow the mid brain is the hind brain. Its front is a large bulge called the pons. Bellow is the medulla.   

  Its functions are involved in activities like automatic movements such as how your eyes which suddenly move to look at an object as it passes by. The medulla keeps together, many nuclei which control respiratory, cardiac, and vasomotor(blood pressure) as well as coughing, sneezing, swallowing, and vomiting. 

  The "little brain" is the bottom and rearmost area of the brain. It, just like the cerebrum has a wrinkled surface but its bulged and other areas contain more regular patterns.  In its anatomy includes the long slim vermis which runs down the middle separating 2 lobes both on the right and left. 

  The cerebellum is involved in movement coordination as well as balance. For example your cerebrum might say move your  right hand forward, and your cerebellum will move your left leg to keep you from falling.
   

Credits to the Human Brain, by Rita Carter.  

Brain Anatomy

The brain has a complicated anatomy. If you remove both left and right cerebral hemispheres of the brain, it exposes many other structures. Some of them have mass and are bigger like the thalamus and some are just a few nerve fibers inside of the larger structures and are only appealing to microscopes. 

The brain anatomy

The brain's parts can be sorted in a few ways and in all of these systems, the cerebral cortex(wrinkled layer) is the dominant structure. The cerebrum is divided into 2 halves, the right and left hemispheres which are linked by nerve fibers. In between the brain contains the hippocampus, thalamus, hypothalamus, and the amyglada, all known as the diencephalon(in between brain). To the naked eye, most of the brain shows as "islands" of gray matter located inside the nerve fiber's white matter. 


Thalamus:A major processing area for inputs to the cerebral cortex.
Amyglada: Part of the limbic system involved in learning and emotions.
Hippocampus: Another part of the limbic system which is deeply involved with short-term memory.

credits: The human Brain by Rita Carter 

Nervous System

 The nervous system is the body's main communication and control system. Nerves lead from each of your sensory organs to the brain in a whole process of chemical and electrical impulses. The nervous system contains the peripheral nervous system (PNS)and the central nervous system(CNS).

Nervous System
The CNS is made of the brain and the spinal chord which are protected by the skull and the spine. The PNS is rather complicated because it is all the nerves. 12 pairs of cranial nerves(nerves extending from brain) and 31 pairs of spinal nerves(nerves from the spinal chord) are contained in the PNS. Both the CNS and PNS work together for sense where nerves pick up messages and senses and send them up the spinal chord(nerve impulses) and to the brain. They both control the skeletal or movement system as well as a series or actions you are unconscious of sometimes in the autonomic system.

Nerves
Nerves communicate using a synapses where chemical and or electrical signal are sent up from neuron to neuron. The spinal chord is made of nerve fibers and is barely the width of a pencil. Some nerves include the optic nerve (visual information, cranial) tibial nerve (nerve in your shin, spinal) Olfactory nerve (smell information, cranial) and many more. The longest cranial nerve is the Vagus nerve which stretches out from the brain stem to the involuntary organs (heart, lungs, etc.).

With different parts and functions the nervous system is a vast network in our body with 86 nerves,  43 on each side of the body. Without this vast network we can not move, sense, and live.