Nervous System

Chapter Summary:
This section was all about the nervous system, both the Central Nervous System called the CNS and the Peripheral Nervous System called the PNS. The nervous system is in my opinion the most important functional system the human body has. The nervous system is what gives us the ability to carry out all other bodily functions. Without a properly functioning nervous system, we would not be able to talk, walk or even digest our food that we eat. If the right part of the nervous system shuts down, it has the ability to shut down vital bodily functions.

Neurons are the basic functioning unit of the nervous system. Neurons allow for the production and conduction of the electrochemical impulses that produce the responses dictated by sensory input. Neurons compose the brain, spinal cord and both central and peripheral nerves. Neurons can vary widely in shape and structure. As shown in the picture below, a neuron contains three different parts. It contains the cell body, the dendrites and the axon.
The cell body is where the cellular activity of the neuron takes place. This is where the nucleus is housed and where the neuron takes in its nutritional needs. The nucleus lies in the middle of the cell body. The cell body is then surrounded by dendrites. Dendrites are the branched area of the cell body. The word dendrite is derived from the Greek word dendron which means "tree branch." The dendrites act as sensors that pick up electrochemical impulses and send the information to the cell body. The tail of the neuron is called the axon. The axon is where conducts electrochemical impulses. The impulses that are conducted along the axon are called action potentials. axons can vary greatly in length from very very short to very long, even up to a meter or more in length!

Myelin is a specialized type of cell called a Schwann cell that surrounds axons. The spaces between myelin sheaths are called Nodes of Ranvier. Myelin acts as a spring board for conduction impulses along axons. The myelin cell will wrap itself around an anxon and the thicker the axon is, the thicker the myelin sheath will be. When an action potential travels down the length of an axon, it can only travel a limited distance down the axon itself with no assistance. The myelin acts as a conduction assistant for the axon. When the conduction hits the nodes of Ranvier, it is able to jump to the next myelin sheath. When the conduction hits the end of that myelin sheath, it then jumps to the next myelin sheath. This process continues all the way down the length of the axon. This process is demonstrated in the picture below. the kangaroo is representing a conduction and it is jumping from myelin sheath to myelin sheath.
In unmeyelinated axons, the conduction can only travel short distances. an unmyelinated axon can only transmit a conduction for a very short distance of 1-2 mm. With a lack of myelin, conductive impulses do not travel well across unmyelinated axons. An unmyelinated axon has to reproduce its action potential each time it reaches its wave limit. Because of the need to be constantly reproducing action potentials, the travel of impulses is very slow across unmyelinated axons.

Dopamine is a complicated neurotransmitter that is present in our bodies. Dopamine is responsible for many different functions within our nervous system. There are 5 different Dopamine receptors in our bodies. Dopamine has many different important functions in our brains. Dopamine is also a hormone that is produced by the pituitary gland. Its function as a hormone is to inhibit the release of products. Prolactin is an important hormone that is involved in lactation in breastfeeding moms. Dopamine is also used to regulate both heart rate and blood pressure. When Dopamine is given as an IV drug through the blood stream, It does not have any effect on the CNS because it cannot cross the blood-brain barrier. When Dopamine needs to be increased in the bran, a drug called Levodopa is given. Levodopa is a precursor to Dopamine and it crosses the blood-brain barrier relatively easily.

Application to Nursing:
When taking care of patients both young and old, the nurse must be able to recognize early signs of neurological deficit. Working in critical care, patients that have a diagnosis of TIA or CVA get admitted a lot. When patients come in with potential neurological issues, it is the nurse's responsibility to detect early changes in the patient's neurological status and be able to report these to the physician. Often people are admitted and it is not known whether they have had a TIA or a CVA. Both conditions present with the same symptoms but they can also differ slightly. The nurse must know the early onset symptoms of each condition. When a patient is suspected of having a Stroke, the NIH Stroke Scale is used to measure neurological deficit. The NIH Stroke Scale is a standard of measure for patients who ave suspected of having a stroke. When a patient has a stoke, the side of the body that is opposite the side of the brain affected suffers from paralysis. The paralysis can be detected by looking at the patient's face when they smile, judging arm drift when the arms are raised, and also having them speak. When a stroke is present in the brain, the deficit of neurological function will appear by using the various tests of the NIH stroke scale.

Beyond strokes, a nurse must be able to see the difference between neurological problems that are part of a degenerative condition that a patient might have versus a new onset of a neurological problem. In older patient, degeneration of neurological function is often present. To the untrained person, they may view a new onset of neurological issues as being part of the normal degeneration process of a patient. In order to facilitate early detection, nurses must be able to make the choice of calling the doctor to further investigate a decline in neurological status instead of just classifying it as general senility or just part of aging.

Case Study:
1. Phyllis is experiencing lack of concentration, forgetfulness, disorientation and just "not being herself." She also has been experiencing fainting spells. Phyllis has also been feeling stressed out.
2. Dehydration could be causing the disorientation and fainting spells.
3. I would think that something more could be going on based on the forgetfulness and the disorientation. If the "just not being herself" is more of a personality change I would be very concerned about that as well. Some neurological disorders have either mild symptoms or no symptoms at all. The mild symptoms that are early signs of neurological disorders can be forgetfulness, some disorientation and personality changes.
4. The first neurological problem that comes to mind is Alzheimer's disease. This comes to mind first because my grandfather had Alzheimer's and his early symptoms were forgetting simple and little things that he should not be forgetting like what hook his car keys hung on, and which barn the tractor was always parked in. His gradually got worse and became more disoriented at times; usually at night. He seemed withdrawn and The nurse must know the early onset symptoms of each condition. not himself like something was bothering him, but he was never sure what it was.
When a patient has a stroke, the NIHhe also reveals that she has been feeling really tired lately. It is also revealed that she has a family history of depression.
6. Some of Phyllis's symptoms could be due to depression. Depression can cause things like fatigue and loss of energy, concentration that is impaired, and slowing of motor movement.
7. Serotonin is the main neurotransmitter believed to be involved in depression. Serotonin works between nerves in the brain and nerves in the body. It has a calming effect and in people with depression, there are not enough receptors that are picking up serotonin. Norepinephrine is also believed to be involved in depression.
8.There are countless things that could have caused her grandfather to be wheelchair bound. They could be neurological or they could be musculoskeletal as well. Neurological causes could be from a TIA or CVA, multiple sclerosis, cerebral palsy, Alzheimer's and Parkinson's disease; just to name a few.
9. Alzheimer's can have an early onset in adults. It is possible that even though Phyllis is only 32, she could be developing early onset Alzheimer's symptoms. These symptoms ofter appear mild at first, but gradually get worse over time. These symptoms can include personality changes, forgetfulness that interferes with daily life, difficulty concentrating and challenges in solving problems.
10. Alzheimer's disease can be hereditary. Family history of Alzheimer's disease is a strong risk factor for a person to develop the disorder.
11. If I were the doctor, I would have Phyllis complete a set of behavioral tests to determine just how severe the problem is. I also would do a CT scan or MRI of the brain to detect and problems with blood flow, and vascular insufficiency, and structural changes that might be occurring. In Alzheimer's disease, the brain degenerates and actually loses matter.
12. 1. Integration 2. Neurotransmitter 3. Calcium 4. Sodium Channels 5.A. Axon 5.B. Node of Ranvier 6. Synapse
13. Myelin is a Schwann Cell.
14. Myelin helps to facilitate conduction of impulses across an axon.
15. In Myelinated axons, the action potentials are generated in the space between axons called the nodes of Ranvier.