Structural Biochemistry/Membrane Proteins/Control Systems:Nervous System

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The nervous system functions by the almost instantaneous transmission of electrochemical signals. Highly specialized cells called neurons control the means of transmission. They are also the functional unit of the nervous system. The neuron is an elongated cell with three parts: dendrites, cell body, and an axon.

The typical neurone contains many dendrites which appear to look like thin branches that extend from the long branch of the cell body. The axon is a single long projection that extends from the cell body. It usually ends in a few small branches called axon terminals. Is is also covered by the myelin sheath to promote neural impulses, or to ensure the signals get transferred smoothly and quickly. Neurons are usually connected in chains and networks. They are physically close to each other, yet never actually come in contact with one another. The gap that separates the axon terminals of one neuron from the dendrites of another neuron is called the synse.

When an electrical impulse moves through the neuron, it starts at the dendrites. Basically, dendrites receive messages from other cells. From there, it passes through the cell body along the axon. Impulses always follow the same path from the dendrite to the cell body, and then the axon. When the electrical impulse reaches the synapse at the end of the axon, special chemicals called neurotransmitters are released. The neurotransmitters will carry a signal across the synapse to the dendrites of the next neuron to restart the process in the next cell. They, as chemical messengers, are called agonists because they open cellular locks or receptors to communicate between the outside and inside of the cell (Medicines by Design 10-11), just like a key fitting into lock.


resting potential

When there is no impulse traveling through a neuron, the cell is said to be at its resting potential. The inside of the cell contains a negative charge in relation to the outside. The cell requires energy to maintain this negative charge. The cell membrane of the neuron contains a protein called Na+/K+ ATPase that uses the energy provided by one molecule of ATP to pump 3 positively charged sodium molecules out of the cell. At the same time, it brings in 2 positively charged K+ ions, creating a system that has a higher concentration of Na+ on the outside and K+ on the inside. A sodium leak channel allows some of the potassium ions to flow out of the cell. Nonetheless, the difference in concentrations creates a net potential difference across the cell membrane of about -70mV, which is the value of the resting potential. The action potential is the electrochemical impulse that can travel along the neuron. The neuron membrane also contains voltage-gated proteins. These proteins will respond to changes in the membrane potential by opening and allowing certain ions to cross that would normally not be allowed to do so. The neuron has both voltage-gated sodium channels and voltage-gated potassium channels. Each one will open under different circumstances.



nervous system






It is a sensory system that carries information from the senses into the central nervous system from the body and motor system that branches out from the CN to organs or muscles. The motor system can be divided into 2 parts: somatic system and the autonomic system, however, the two systems work together to ensure a proper internal states to avoid any extreme responses.




Parkinson’s Disease (PD) is a degenerative disorder affecting the nervous system. This is caused by low levels of the neurotransmitter dopamine produced in the brain. Evident symptoms include trembling or stiffness in body limbs or face, instability in posture, or lack of balance and body coordination. These symptoms can cause labor in simple tasks, such as walking and talking. The severity in the impairment of the motor skills differ between individuals. Some may become critically disabled and others may only suffer from minor motor trembling. This is a chronic disease that usually affects people around the age of 50. There is no cure for this disease, therefore, the symptoms progressively worsens over time.

Wilson Disease

The Wilson Disease is a inherited mutation on chromosome 13. This disorder causes a person's body from removing excess build up of copper. The protein that is in charge of the removal of copper is ceruloplasmin. With the inability for one to be able to remove copper can lead to cirrhosis, which is the damaging of liver cells and hindering the liver function. Evident symptoms of having the Wilson Disease is having extreme body tremors and decrease in speed in body movement. Also, the person's mental capabilities will decrease and emotionally sensitive, especially temperamental. Treatment can include avoid eating any food that contains copper or chelating the excess copper to remove from the body.

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