The human brain is truly an impressive organ. Unlike every other animal on earth, the brain gives us the ability to talk, imagine and solve a variety of problems. A detailed overview of this organ allows us to better understand how the brain works, and also reveals the remarkable inner workings that routinely occur inside this machine.
The Brain's Nuts and Bolts
Inside your brain are neurons, nerve cells that send messages throughout your body. Your brain contains approximately 100 million of these cells, which it uses to send singals to various body parts. Neurons can transmit messages over relatively long distances, usually up to several feet. The neuron can be broken up into three main parts: the cell body/soma, the axon and the dendrites/nerve endings.
Cell Body/Soma - The cell body contains every piece that the neuron needs to function properly. These pieces include the nucleus, the endoplasmic reticulum, ribosomes and mitochondria. Ribosomes are used by neurons to by your cells to make proteins, whereas mitochondria are tasked with making energy for the cell.
Axon -Axons are shaped like long cables, and have the responsibility of carrying electrochemical messages throughout the entire cell. Some axons are covered in a layer of insulation known as the myelin sheath. The myelin sheath consists of protein and fat, and enables nerve impulses to be spread quickly through the axon. Neurons with the myelin sheath layer are typically found in peripheral nerves outside the brain and spinal cord. Likewise, neurons found inside the brain and spinal cord do not have this layer of insulation.
Dendrites/Nerve Endings - Think of dendrites as telephone cables for neurons. Dendrites look like braches jutting out from the neuron. Each cell will usually have multiple dendrites, located on one or both sides of the cell.
The Many Faces of Neurons
There are three types of neurons within the body - sensory neurons, motor neurons and interneurons. A sensory neuron typically has two dendrites, with one attached to each end of the neuron. The two dendrites are strung together by an axon. Your body relies on sensory neurons to carry signals from the outer parts of the body to the central nervous system.
Motor neurons, on the other hand, have the exact opposite responsibility, as they transport signals from the central nervous system to the body's muscles, skin and glands. They also control muscle contractions. A motor neuron has its cell body on one end with its dendrites on the other; the two parts are connected by an axon.
Interneurons act as bridges between sensory neurons and motor neurons, exchanging messages between the two types of nerve cells. Without interneurons, it would not be possible for sensory and motor neurons to communicate with each other. Interneurons have a total of two axons, with one sticking out of each side. Dendrites are located on the end of each axon.
Ever wonder why your leg kicks upward when a doctor taps a certain spot on your knee with a rubber hammer? The answer lies in the activity between your neurons. When the hammer hits your leg, receptors in your leg use a sensory neuron to send a message to the spinal cord. The same sensory neuron also contacts a motor neuron, which in turn prompts the muscles in your leg to contract via nerve impulses, resulting in a kicking motion.
This type of muscular movement uses a monosynaptic reflex pathway; in other words, since the reaction is quick and simple, your body does not require the brain's involvement. Essentially, this kind of reaction represents an automatic and hardwired response.
The Four Main Parts of Your Brain
Every person's brain contains four critical parts that are used on a constant basis. These parts are called the brain stem, the cerebellum, the hypothalamus and the cerebrum.
Brain Stem - This part of the brain controls automatic bodily functions, such as heart rate and blood pressure.
Cerebellum - The cerebellum handles incoming information regarding an individual's sense of balance and space, which it uses to determine limb movements.
Hypothalamus/Pituitary Gland - If you are wondering which part of the brain controls your behavioral patterns, look no further. The hypothalamus and pituitary gland control your responses to various situations, such as eating, drinking, sexual responses, aggression and pleasure.
Cerebrum - The cerebrum is a relatively complex part of your brain, as it consists of a number of key secondary pieces. These component parts include the cortex, large fiber tracts and various other structures found deep inside the cerebrum. Given the massive role that the cerebrum plays in your brain, it's no wonder why it requires so many tools. Your body's sensory organs send all of their information to the cerebrum, which assembles the data into a complete and clear picture of your surroundings. The cerebrum also determines motor functions and initiates all emotions and thought processes. In addition, the cerebrum also serves as your brains' memory bank.
A Look at the Lower Brain
Like other areas of the brain, the lower brain is an assembly of parts that make specific contributions to the organ's daily operations. These parts include the spinal cord, brain stem and diencephalon. Making the lower brain even more complex are the pieces that make up the spinal cord, namely the medulla, pons, midbrain, thalamus and hypothalamus. Each of these parts contains nuclei, specialized groups of cells that enable your body to perform specific tasks.
Medulla - Your blood pressure and breathing are controlled by the medulla's nuclei, which also transport information from sensory organs to other parts of the brain.
Pons - The nuclei in this part of the lower brain assist you with breathing, sleeping and tasting. In addition, the pons's nuclei transmit data from the cerebellum to the cortex regarding your body's movements and positioning, and act as bridge between your medulla and midbrain.
Midbrain - With so many parts of the brain involved in motor functions, the brain needs a mechanism to link these parts together into a cohesive unit. Enter the midbrain, which also helps regulate movements that you consciously perform (these types of actions are called voluntary movements).
Thalamus - The thalamus serves as a gateway of sorts, as it determines which sensory information is consciously processed by your brain. Essentially, it determines which external stimuli and events you actually notice. It also sorts out sensory data, sending such input to the appropriate areas of the cortex.
Hypothalmus - The hypothalamus plays a major role in your everyday behavior, as its nuclei controls eating, drinking, sexual reproduction and growth. Your brain's biological clock, which tells you when to wake up and go to bed, is largely run by the hypothalamus.
The brain is truly a fascinating organ, with a number of auxiliary parts that enable it to function like a highly functional computer. Given its complexity, detail and capabilities, it comes as no surprise that scientists regard it as wonderful piece of human machinery.
Michael Harris is a contributor to Natural Knowledge 24/7, a monthly newsletter focusing on health and wellness issues. This article, along with many others covering a wide range of subjects, can be found at http://naturalknowledge247.com/
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