- 1) Peripheral Nervous System
- 2) Cranial Nerves
- 3) Spinal Nerves
- 4) Somatic Nervous System
- 5) Autonomic Nervous System
- 6) Sympathetic Nervous System
- 7) Parasympathetic Nervous System
- 8) Nervous Disorders
- 9) Epilepsy:
- 10) Alzheimer’s disease:
- 11) Action of Nicotine on Nervous System:
- 12) FAQs: Peripheral Nervous System
- 13) Conclusion: Understanding the Peripheral Nervous System and Its Disorders
- 14) You may also like to learn:
Peripheral Nervous System
The human nervous system is divided into two parts, the central nervous system, and the peripheral nervous system. The CNS consists of the brain and spinal cord while PNS describes the parts of the nervous system outside the brain and spinal cord. It consists of the cranial nerves, spinal nerves, and their roots and branches, peripheral nerves, and neuromuscular junctions.
It consists of sensory neurons and motor neurons, which may form ganglia and nerves. Ganglia are the concentrations of cell bodies of neurons. The nerves are the packages of axons or dendrites, bounded by connective tissue. They may be sensory-motor or mixed nerves depending upon the direction of impulse they conduct.
Cranial Nerves
In humans, there are 12 pairs (24) of nerves, which arise from the brain or lead to the brain. These nerves are called cerebral or cranial nerves. A few of these nerves are sensory, some motor, and some are mixed.
Spinal Nerves
From the spine 31 sets (62) of spinal nerves emerge or lead to the spinal cord. All these nerves are combined having fibers of both sensory and motor neurons.
The peripheral nervous system is further divided into two parts: the somatic nervous system and the autonomic nerve system.
Somatic Nervous System
The word soma stems from Greek which means” body”. The somatic system is the part of the peripheral nervous system responsible for bringing sensory and motor information to and from the central nervous system. The somatic system is responsible for sending sensory details along with voluntary movement. This system consists of two major types of neurons:
Motor neurons: Also called efferent nerve cells, motor neurons carry information from the brain and spine to muscle fibers throughout the body. These motor neurons permit us to take physical action in response to stimuli in the environment.
Sensory neurons: Also called afferent neurons, sensory neurons carry information from the nerves to the central nervous system. It is these sensory neurons that enable us to take in sensory information and send it to the brain and spine.
Autonomic Nervous System
The autonomic system is the part of the peripheral nervous system that’s responsible for controlling involuntary body functions, such as blood circulation, heartbeat, digestion, and breathing.
Simply put, it is the autonomic system that manages elements of the body that are generally not under voluntary control. This system enables these functions to occur without requiring to purposely to consider them occurring. The autonomic system is further divided into 2 parts:
Sympathetic Nervous System
Most ganglion fibers of the sympathetic system develop from the middle portion of the spine and almost end in the ganglia that lie near the spinal cord.
Functions:
This system is essential throughout emergency circumstances and is associated with “fight or flight.” This system accelerates the heartbeat, dilates the pupil, and hampers the digestion of food, etc.
Parasympathetic Nervous System
A couple of cranial nerves including the vagus nerve together with the nerves from the bottom portion of the spinal cord, create the parasympathetic nervous system.
Functions:
It promotes all the internal actions which are associated with the relaxed state i.e. contraction of the pupil, digestion of food, and slowing down heartbeat.
Nervous Disorders
Following are a few of the common disorders of the nervous system in humans:
Parkinson’s disease:
Symptoms:
It is a nervous disorder, specified by involuntary tremors, reduced motor power, and rigidity. The mental faculties are not affected.
Causes:
The disease is thought to be caused by cell death in a brain area that produces dopamine. The disease might result by head trauma.
Onset of Disease:
The start of disease is typically in 50’s and 60’s. The disease is gradually progressive; the patient might live for many years.
Cure:
Effective drugs are offered such as L- dopa. A naturally occurring protein called glial cell-line derived: neurotrophic factor (GDNF) has actually been shown to boost uptake of dopamine when provided to lab rats and monkeys. GDNF might be utilized in the future for people in the treatment of this disease.
Epilepsy:
Symptoms:
It is one of the convulsive disorders of nerves that are characterized by abrupt transient symptoms of motor, sensory, psychic, or autonomic nature, often related to changes in consciousness. These changes are believed to be secondary to unexpected transient alterations in brain function related to excessive fast electrical discharges in the gray matter.
Onset of Disease:
The beginning of epilepsy is generally before age 30. Later on, age-onset suggests natural disease. In some patients, psychological or emotional disturbances play a significant “trigger” function.
Treatment:
Electroencephalography (EEG) is the most important test in the research study of epilepsy. Anticonvulsant drugs are used. Alcohol aggravates epilepsy, so persons suffering from epilepsy ought to avoid alcohol.
Alzheimer’s disease:
Alzheimer’s disease was first explained by Alois Alzheimer in 1907.
Signs:
It is defined by the decline in brain function. Its symptoms resemble those diseases that cause dementia (amnesia/ memory loss). There is a hereditary predisposition to the disease in some people, so it tends to run in families.
Onset of Disease:
There is proof that high levels of aluminium may contribute to the start of this disease. There is also a decline in brain function with age.
Action of Nicotine on Nervous System:
Nicotine affects the postsynaptic membrane in CNS and PNS. It mimics the action of acetylcholine on nicotine receptors, so it is a stimulant of the nerve impulse. It increases the heartbeat rate, blood pressure, and digestive tract movement. Nicotine may induce vomiting and diarrhoea and even may cause water retention relation by kidneys.
FAQs: Peripheral Nervous System
1. What is the Peripheral Nervous System (PNS)?
- The PNS is one of the divisions of the human nervous system. It includes all nervous structures outside the brain and spinal cord, encompassing cranial nerves, spinal nerves, peripheral nerves, and neuromuscular junctions.
2. How is the PNS organized?
- The PNS is organized into sensory neurons and motor neurons. Ganglia, concentrations of neuron cell bodies, and nerves, bundles of axons or dendrites, are key components. Nerves can be sensory, motor, or mixed based on the direction of impulse conduction.
3. How many pairs of cranial nerves are there in humans?
- Humans have 12 pairs (24 in total) of cranial nerves that either arise from or lead to the brain. These nerves serve sensory, motor, or mixed functions.
4. What are spinal nerves, and how many sets are there?
- There are 31 sets (62 in total) of spinal nerves that emerge from or lead to the spinal cord. These nerves contain fibers of both sensory and motor neurons.
5. What are the divisions of the Peripheral Nervous System?
- The PNS is divided into the Somatic Nervous System (responsible for voluntary movement) and the Autonomic Nervous System (controlling involuntary functions like heartbeat and digestion).
6. What is the Somatic Nervous System responsible for?
- The Somatic Nervous System is responsible for transmitting sensory and motor information to and from the central nervous system. It enables voluntary movement and comprises motor and sensory neurons.
7. What functions does the Autonomic Nervous System control?
- The Autonomic Nervous System controls involuntary body functions such as blood circulation, heartbeat, digestion, and breathing, allowing these processes to occur without conscious effort.
8. How is the Autonomic Nervous System further divided?
- The Autonomic Nervous System is divided into the Sympathetic Nervous System (associated with “fight or flight” responses) and the Parasympathetic Nervous System (associated with relaxed states and internal functions).
9. What are common nervous disorders in humans?
- Common nervous disorders include Parkinson’s disease (involuntary tremors and reduced motor power), epilepsy (convulsive disorders), and Alzheimer’s disease (decline in brain function).
10. How does nicotine affect the nervous system? – Nicotine acts as a stimulant on the nervous system, affecting both the CNS and PNS. It mimics acetylcholine’s action on nicotine receptors, leading to increased heartbeat, blood pressure, and intestinal movement.
11. What is the treatment for Parkinson’s disease? – Parkinson’s disease is treated with drugs such as L-dopa. Experimental treatments like glial cell-line derived neurotrophic factor (GDNF) show promise in enhancing dopamine uptake and may be explored further in human treatment.
12. How is epilepsy diagnosed and treated? – Epilepsy is diagnosed using Electroencephalography (EEG), and treatment involves anticonvulsant drugs. Alcohol, known to worsen epilepsy, should be avoided by individuals suffering from the condition.
Conclusion: Understanding the Peripheral Nervous System and Its Disorders
This intricate system operates through the collaboration of sensory and motor neurons, forming the basis for the classification of nerves as sensory-motor or mixed. Cranial nerves, emerging from or leading to the brain, and spinal nerves, emanating from the spine, play crucial roles in facilitating communication between the body and the CNS.
Further dissecting the PNS, we encounter the Somatic Nervous System, aptly named for its involvement in voluntary movements and the transmission of sensory information. Motor neurons, steering physical actions in response to stimuli, and sensory neurons, channeling information to the CNS, constitute the fundamental components of this system.
The Autonomic Nervous System, another facet of the PNS, takes charge of involuntary bodily functions, including blood circulation, heartbeat, digestion, and breathing. It operates seamlessly, allowing these functions to occur without conscious intervention. The Autonomic Nervous System further divides into the Sympathetic Nervous System, activated during emergencies for the “fight or flight” response, and the Parasympathetic Nervous System, promoting internal actions associated with a relaxed state.
As we navigate through the functions of the PNS, we encounter the challenges posed by nervous disorders. Parkinson’s disease, characterized by involuntary tremors and reduced motor power, underscores the intricate nature of the nervous system. The onset, causes, and potential treatments for Parkinson’s disease showcase the ongoing efforts to understand and manage such neurological complexities.
Epilepsy, a convulsive disorder, introduces the notion of abrupt transient symptoms and the role of electrical discharges in the gray matter. Diagnostic tools like Electroencephalography (EEG) and anticonvulsant drugs become crucial in addressing epilepsy, emphasizing the interdisciplinary approach to nervous system disorders.
Finally, Alzheimer’s disease, marked by a decline in brain function and genetic predisposition, prompts reflection on the multifaceted nature of nervous system-related ailments. The exploration of potential contributors, such as high levels of aluminum, underscores the ongoing quest for comprehensive understanding and effective interventions.
In our journey through the complexities of the nervous system, the role of nicotine on the postsynaptic membrane emerges, shedding light on its stimulant effects and the physiological responses it elicits.
In conclusion, the study of the Peripheral Nervous System opens a gateway to unraveling the mysteries of human neurobiology, paving the way for advancements in diagnosis, treatment, and our overall comprehension of neurological disorders. The ongoing pursuit of knowledge in this field promises to illuminate new avenues for enhancing both the quality of life and the understanding of the intricate dance of neurons within us.