This quiz is going to focus on the human nervous system. What is the nervous system? It is a collection of nerves, as well as cells known as neurons. The nerves and neurons transmit signals throughout the entire body. In science and in medicine, the study of the nervous system is known as neurology and a doctor of the nervous system is a neurologist.
You can think of the nervous system as a type of hard drive in a computer that sends out electrical signals to every part of the body. The nerves look like fiber strands that branch outward from the brain and central cord. For the most part, the nervous system is made up of two parts. There is the central nervous system which consists of the brain, the spinal cord and travels upward to the retina (yes the eye and more specifically, the light sensitive layer of the eye).
Second, there is the peripheral nervous system which consists of neurons (nerve fibers) that branch out from the spinal cord. These nerve fibers extend to the neck, the arms, the torso, the legs, the skeletal muscles and, finally, the internal organs. Ganglia (which are clusters of neurons) connect neurons to each other, as well as to the central nervous system.
The role of neurons is to transmit signals to each cell through the fiber strands. The fiber stands are also known as axons. The axons will then cause neurotransmitters (chemicals) to be released at specific junctions throughout the nervous system. These junctions are known as synapses. The synapses then send commands to various designated cells to create a reaction. The entire process from first signal to the ultimate reaction to that signal takes less than a millisecond.
Types of Neurons
Sensory neurons will react to physical stimuli like temperature, sound, touch and light. These neurons will send a signal back to the nervous system which tells the body what the surrounding physical environment is like. The signal will tell you to shiver if cold or sweat if hot, or shield your eyes if the light is bright.
The central nervous system also contains motor neurons. Motor neurons send out signals that will activates muscles and glands. The simple act of sitting or standing up falls under this type of signal. Even chewing, swallowing and laughing.
Sensory neurons often work hand-in-hand with motor neurons. For example, the sensory neurons in the hand will send a signal that fire is hot which then triggers the motor neurons to make the hand pull away from the fire.
In order for the neurons to work properly, however, they need to stay stationary. This is performed by glial cells which act like a kind of glue to keep them in place. The glial cells also provide the neurons with nutrients.
Diseases of the Nervous System
The nervous system is protected rather well by the bone of the skull and the spinal column. However, it can be damaged with accidents, such as a car accident or sports accident, or old age can make the bones more brittle and allow damage to the nervous system to occur. The damage makes the nervous system susceptible to diseases. Among some of the diseases that can occur to the nervous system are the following:
Stroke (occur when the brain does not receive enough oxygen)
Subdural hemorrhage and hematoma (bleeding in the brain)
Epilepsy (electrical signals in the brain misfire causing seizures)
Parkinson’s disease (affects the signals to the body’s muscles)
Multiple Sclerosis (scar tissue surrounds the nerves making transmitting a signal weak or completely absent – affecting muscle control and causes a slurred speech)
Alzheimer (affects the brain and memory functions)
