Somatic and Autonomic nervous system: Definition and Function Anatomy, Disorders

Somatic and Autonomic nervous system

Table of content

I. Somatic Nervous System

• Definition and Function
• Anatomy
• Motor Pathway
• Sensory Pathway
• Reflex Arcs
• Disorders

II. Autonomic Nervous System

• Definition and Function
• Anatomy
• Divisions
• Conclusion
• FAQs

Somatic Nervous System

The somatic nervous system is a part of the peripheral nervous system that is responsible for the voluntary control of skeletal muscles and for gathering sensory information from the body and transmitting it to the central nervous system. It is involved in activities such as movement, perception, and reflexes.

The somatic nervous system consists of motor neurons and sensory neurons. The motor neurons are responsible for transmitting signals from the central nervous system to the skeletal muscles, causing them to contract and produce movement. The sensory neurons are responsible for transmitting information from the skin, muscles, and joints back to the central nervous system, allowing the brain to perceive sensations such as touch, temperature, and pain.

The motor pathway of the somatic nervous system involves a single neuron that travels from the spinal cord or brainstem to the skeletal muscle it innervates. The sensory pathway involves a chain of neurons that transmits information from the sensory receptor to the spinal cord or brainstem, where it is processed and interpreted.

Reflex arcs are another important aspect of the somatic nervous system. They are rapid and involuntary responses to stimuli that help protect the body from harm. Reflex arcs involve a sensory neuron, an interneuron, and a motor neuron, and they bypass the brain to allow for quick responses.

Definition and Function:

The somatic nervous system is a division of the peripheral nervous system that controls voluntary movements and sensations, such as those involved in walking, running, and feeling pain or pressure. It is responsible for transmitting sensory information from the body to the central nervous system (CNS) and for transmitting motor commands from the CNS to the body's muscles, allowing for voluntary movement.

Anatomy:

The somatic nervous system includes sensory neurons that carry information from the body's sensory organs, such as the skin, eyes, and ears, to the CNS. It also includes motor neurons that carry information from the CNS to the body's muscles. These neurons are located in the spinal cord and cranial nerves.

Motor Pathway:

The motor pathway of the somatic nervous system consists of a single neuron that extends from the CNS to the skeletal muscles. This neuron releases the neurotransmitter acetylcholine, which binds to receptors on the muscle cells, causing them to contract.

Sensory Pathway:

The sensory pathway of the somatic nervous system consists of three neurons. The first neuron carries sensory information from the sensory organ to the spinal cord or brainstem. The second neuron carries this information from the spinal cord or brainstem to the thalamus. The third neuron carries the information from the thalamus to the somatosensory cortex in the brain, where it is processed and interpreted.

Reflex Arcs:

Reflex arcs are rapid, involuntary responses to sensory stimuli that do not require input from the brain. They are mediated by the spinal cord and involve a sensory neuron, an interneuron, and a motor neuron. When a sensory receptor is stimulated, the sensory neuron sends an impulse to the spinal cord, which activates the interneuron. The interneuron then sends a signal to the motor neuron, which causes the appropriate muscle to contract.

Disorders:

Disorders of the somatic nervous system can affect both motor and sensory function. Some common disorders include peripheral neuropathy, myasthenia gravis, and spinal cord injuries. These conditions can cause symptoms such as weakness, numbness, and paralysis, and may require medical intervention to manage symptoms and prevent further damage.

Autonomic Nervous System

The autonomic nervous system (ANS) is a division of the peripheral nervous system that controls involuntary functions, such as heartbeat, breathing, digestion, and sweating. It is responsible for regulating bodily processes that are necessary for survival and maintaining homeostasis, or a stable internal environment.

The ANS is divided into two branches: the sympathetic nervous system and the parasympathetic nervous system. These two branches have opposing effects on the body, allowing for fine-tuned control of bodily functions.

The sympathetic nervous system is responsible for the body's "fight or flight" response. It is activated in response to stress or danger and triggers physiological changes such as increased heart rate and blood pressure, dilation of the pupils, and inhibition of digestion.

The parasympathetic nervous system, on the other hand, is responsible for the body's "rest and digest" response. It is activated during times of relaxation and promotes digestion, decreases heart rate and blood pressure, and constricts the pupils.

The ANS is controlled by a complex network of neurons located in the brainstem and spinal cord, as well as by feedback from sensory receptors located throughout the body. In addition to the sympathetic and parasympathetic branches, there is also a third branch called the enteric nervous system, which is responsible for regulating the digestive system.

Definition and Function:

The autonomic nervous system (ANS) is a part of the peripheral nervous system that regulates involuntary bodily functions such as heart rate, blood pressure, breathing, and digestion. It helps to maintain homeostasis, or balance, within the body by responding to internal and external stimuli.

Anatomy:

The ANS is composed of two types of neurons: preganglionic and postganglionic neurons. Preganglionic neurons originate in the brainstem or spinal cord and synapse with postganglionic neurons located in the ganglia outside of the CNS. The ganglia of the ANS are located in two parallel chains along either side of the spinal column, as well as in the head, neck, and abdomen. The ANS also includes sensory neurons that transmit information from internal organs to the CNS for processing and interpretation.

Divisions:

The ANS is divided into two main branches, the sympathetic and parasympathetic nervous systems, which have opposing effects on bodily functions.

Sympathetic Nervous System (SNS):

The SNS is responsible for the "fight or flight" response and prepares the body to respond to stress or danger. It increases heart rate, respiratory rate, and blood pressure while decreasing digestion and blood flow to non-essential organs. The SNS is activated by the release of the hormone adrenaline (epinephrine) from the adrenal glands.

Parasympathetic Nervous System (PNS):

The PNS is responsible for the "rest and digest" response and promotes relaxation and recovery. It decreases heart rate and blood pressure, increases digestion and nutrient absorption, and stimulates the immune system. The PNS is activated by the release of the neurotransmitter acetylcholine.

Conclusion

The nervous system plays a crucial role in regulating bodily functions and maintaining homeostasis. The somatic nervous system controls voluntary movements and sensory functions, while the autonomic nervous system regulates involuntary functions such as heart rate, breathing, and digestion. The autonomic nervous system is further divided into the sympathetic and parasympathetic nervous systems, which have opposing effects on the body and work together to maintain balance. 

Understanding the functions and anatomy of these two systems can help us better understand and manage various neurological disorders that affect our daily lives. By working in harmony, the somatic and autonomic nervous systems help us to function and thrive in our daily lives.

FAQs

Can You Provide Examples Of The Somatic Nervous System In Action?

Certainly! The somatic nervous system is responsible for controlling voluntary movements and transmitting sensory information from the body to the central nervous system. Here are a few examples of the somatic nervous system in action:

Walking: When you decide to walk, the somatic nervous system activates the muscles in your legs and feet, allowing you to move. It coordinates the contraction and relaxation of various muscles to produce the desired movements.

Writing: When you hold a pen or pencil and write, the somatic nervous system controls the fine motor movements of your hand and fingers. It allows you to manipulate the writing instrument and create legible handwriting.

Playing a Musical Instrument: Whether it's playing the piano, guitar, or any other instrument, the somatic nervous system is involved. It coordinates the precise movements of your fingers, hands, and arms, enabling you to press the right keys or strings to produce the desired sounds.

Catching a Ball: When you see a ball coming towards you and instinctively reach out to catch it, the somatic nervous system is responsible for the quick and coordinated movements of your arms and hands. It enables you to time your actions and adjust your grip to successfully catch the ball.

Feeling Pain: The somatic nervous system also plays a role in transmitting sensory information related to pain. When you touch a hot surface or experience an injury, sensory receptors in your skin send signals to the central nervous system, which then interprets the information as pain.

Reflexes: Reflex actions, such as the knee-jerk reflex, are mediated by the somatic nervous system. For example, when a doctor taps your knee with a reflex hammer, the sensory receptors in your knee send a signal to your spinal cord, which then triggers an automatic contraction of the corresponding muscle, causing your leg to jerk.

These are just a few examples of how the somatic nervous system operates in everyday activities involving voluntary movements and sensory perception.

How Would You Define The Somatic Nervous System In The Context Of Psychology?

In the context of psychology, the somatic nervous system refers to the division of the peripheral nervous system that is responsible for controlling voluntary movements and transmitting sensory information between the central nervous system (brain and spinal cord) and the body's sensory receptors and skeletal muscles. It is one of the two main divisions of the peripheral nervous system, with the other being the autonomic nervous system.

The somatic nervous system primarily deals with conscious and voluntary activities. It allows individuals to interact with their environment by controlling their body movements, perceiving sensory stimuli, and responding to them. It involves both sensory neurons, which transmit information from sensory receptors to the central nervous system, and motor neurons, which carry signals from the central nervous system to skeletal muscles, enabling voluntary movements.

The somatic nervous system is involved in a wide range of psychological processes and behaviors. It plays a crucial role in motor skills, coordination, sensory perception, and the conscious experience of the external world. It allows individuals to engage in activities such as walking, talking, writing, playing sports, and interacting with the environment through physical actions. Additionally, it mediates the experience of physical sensations, such as touch, temperature, pain, and proprioception (the sense of body position and movement).

In summary, the somatic nervous system, within the field of psychology, refers to the division of the peripheral nervous system that controls voluntary movements and relays sensory information between the central nervous system and the body's sensory receptors and skeletal muscles.

Can You Give Examples Of The Autonomic Nervous System At Work?

Certainly! The autonomic nervous system (ANS) is responsible for regulating involuntary functions of the body, including processes that occur automatically and without conscious control. It consists of two main divisions: the sympathetic nervous system and the parasympathetic nervous system. Here are some examples of the autonomic nervous system at work:

Fight or flight response: In a stressful or threatening situation, the sympathetic division of the ANS is activated. This triggers a cascade of physiological changes, such as increased heart rate, elevated blood pressure, dilated pupils, accelerated breathing, and release of stress hormones like adrenaline. These responses prepare the body for a rapid response to danger or stress.

Digestion: The parasympathetic division of the ANS is responsible for promoting digestion and nutrient absorption. When we eat a meal, this division is activated, leading to increased blood flow to the digestive organs, stimulation of stomach acid and enzyme secretion, and enhanced gut motility to facilitate digestion and absorption of nutrients.

Salivation and Lacrimation: The parasympathetic division controls salivation (production of saliva) and lacrimation (production of tears). When we smell food or experience emotional stimuli, the parasympathetic system stimulates salivary glands to produce saliva, aiding in digestion. Similarly, it triggers tear production to keep our eyes lubricated and protected.

Heart rate regulation: Both divisions of the ANS play a role in heart rate regulation. The sympathetic division increases heart rate and strengthens the force of heart contractions, preparing the body for physical exertion or stress. Conversely, the parasympathetic division slows down the heart rate during periods of rest and relaxation.

Pupil constriction and dilation: The ANS controls the size of our pupils to regulate the amount of light entering the eyes. In bright conditions, the parasympathetic system causes constriction of the pupils to reduce the amount of light. In dim conditions, the sympathetic system triggers dilation of the pupils to allow more light to enter and improve vision in low-light situations.

Sweating: The sympathetic division of the ANS controls sweating to regulate body temperature. When body temperature rises, such as during exercise or exposure to heat, the sympathetic system activates sweat glands to release sweat, which evaporates from the skin surface, cooling the body.

What Are The Four Functions That The Autonomic Nervous System Can Perform?

The autonomic nervous system (ANS) performs several essential functions to regulate involuntary processes within the body. Although there are many functions attributed to the ANS, they can generally be categorized into four main areas:

Regulation of Internal Organs: One of the primary functions of the ANS is to regulate and maintain the functioning of internal organs, ensuring their optimal performance. This includes controlling processes such as heart rate, blood pressure, digestion, respiration, urinary function, and hormonal secretion. The ANS achieves this by coordinating the activities of various organs and systems to maintain homeostasis.

Mobilization of Energy: The ANS is responsible for mobilizing energy resources in response to different situations and demands. The sympathetic division of the ANS activates the "fight or flight" response, preparing the body for action in times of stress, danger, or physical exertion. It increases heart rate, blood flow to muscles, and the release of glucose from energy stores, providing the necessary resources for immediate action.

Maintenance of Body Temperature: The ANS plays a vital role in regulating body temperature. It ensures that the body maintains a stable internal temperature by adjusting factors such as blood flow to the skin, sweating, and shivering. When the body becomes too warm, the ANS triggers sweating and vasodilation of blood vessels to dissipate heat. Conversely, when the body becomes too cold, the ANS triggers vasoconstriction and shivering to conserve heat.

Emotional Responses and Homeostasis: The ANS is involved in emotional responses and maintaining overall homeostasis in the body. It contributes to the expression of emotions by influencing physiological changes associated with emotional states, such as changes in heart rate, breathing pattern, and perspiration. Additionally, the ANS helps maintain the balance of bodily functions, adapting to changes in the external environment and internal conditions to ensure stability and equilibrium.

What Are The Names Of Somatic Disorders?

There are various somatic disorders, also known as somatic symptom disorders or somatoform disorders, that are characterized by physical symptoms or concerns that are disproportionate or excessive compared to any known medical condition. Here are a few examples of somatic disorders:

Somatic Symptom Disorder (SSD): This disorder involves the presence of one or more distressing physical symptoms that are accompanied by excessive thoughts, feelings, or behaviors related to the symptoms. The symptoms are not explained by any known medical condition and cause significant distress or impairment in daily functioning.

Illness Anxiety Disorder (formerly Hypochondriasis): This disorder is characterized by persistent anxiety or fear about having a serious medical condition, despite medical evaluations and reassurances indicating the absence of any significant illness. Individuals with this disorder may excessively focus on bodily sensations, misinterpret them as signs of a severe illness, and engage in repeated medical visits or excessive health-related behaviors.

Conversion Disorder (Functional Neurological Symptom Disorder): Conversion disorder involves the presence of neurological symptoms or deficits that are inconsistent with known medical conditions. These symptoms may include weakness, paralysis, blindness, or seizures. The symptoms are believed to be influenced by psychological factors or stressors, and there is often a significant impairment in functioning.

Body Dysmorphic Disorder (BDD): BDD is characterized by an excessive preoccupation with perceived defects or flaws in one's physical appearance. Individuals with BDD may focus on a specific body part, often spending significant time engaging in repetitive behaviors or rituals, such as excessive grooming or seeking reassurance about their appearance. The concerns about their appearance are not adequately explained by the actual appearance and cause distress or impairment.

Pain Disorder: Pain disorder involves persistent pain that is the primary focus of clinical attention and is not better explained by another medical or mental health condition. The pain may be associated with significant distress, impairment, and excessive preoccupation with the pain. This disorder is now categorized as a "chronic pain disorder" in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5).

What Are 3 Disorders Of The Nervous System?

There are numerous disorders that can affect the nervous system, which is comprised of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves outside the brain and spinal cord). Here are three examples of disorders that can affect the nervous system:

Alzheimer's Disease: Alzheimer's disease is a progressive neurological disorder that primarily affects the brain, leading to memory loss, cognitive decline, and changes in behavior. It is characterized by the accumulation of abnormal protein plaques and tangles in the brain, which disrupt the communication between nerve cells, causing their degeneration and eventual loss. Alzheimer's disease is the most common cause of dementia.

Multiple Sclerosis (MS): Multiple sclerosis is an autoimmune disorder in which the immune system mistakenly attacks the protective covering (myelin) of nerve fibers in the central nervous system. This results in inflammation, demyelination, and scarring of the affected areas, disrupting the transmission of nerve signals. MS can lead to various symptoms, including muscle weakness, balance problems, coordination difficulties, and sensory disturbances.

Parkinson's Disease: Parkinson's disease is a progressive neurodegenerative disorder that primarily affects the movement control centers in the brain. It is characterized by the loss of dopamine-producing cells in a region called the substantia nigra, leading to motor symptoms such as tremors, rigidity, bradykinesia (slowness of movement), and postural instability. Parkinson's disease can also involve non-motor symptoms like depression, sleep disturbances, and cognitive impairment.

What Is The Difference Between The Pns And The Ans?

The peripheral nervous system (PNS) and the autonomic nervous system (ANS) are two components of the overall nervous system. Here are the differences between the PNS and the ANS:

Peripheral Nervous System (PNS):

• The PNS consists of nerves and ganglia (clusters of nerve cell bodies) located outside the brain and spinal cord.
• It serves as a communication network between the central nervous system (CNS) and the rest of the body.
• The PNS is responsible for transmitting sensory information from the body's sensory receptors to the CNS and conveying motor commands from the CNS to the muscles and glands.
• It is divided into two main components: the somatic nervous system (SNS) and the autonomic nervous system (ANS).

Autonomic Nervous System (ANS):

• The ANS is a division of the PNS that regulates involuntary bodily functions and controls internal organs and glands.
• It operates without conscious control and helps maintain internal homeostasis.
• The ANS has two primary divisions: the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS).
• The sympathetic division mobilizes the body's "fight or flight" response in times of stress or danger, increasing heart rate, dilating pupils, and redirecting blood flow to muscles.
• The parasympathetic division promotes relaxation, digestion, and restoration of bodily functions during restful periods. It helps conserve energy and supports restorative processes.
• Both divisions of the ANS work in a dynamic balance, constantly adjusting and responding to internal and external stimuli to maintain equilibrium.

What Is a Somatic Nervous System Example?

A somatic nervous system example involves any voluntary movement or sensory experience that is under conscious control. Here's an example of the somatic nervous system in action:

Let's consider the act of picking up a glass of water from a table. In this scenario:

Voluntary Movement: The somatic nervous system activates the muscles in your arm, hand, and fingers to perform the precise movements required to reach for the glass, grasp it, and lift it.

Sensory Perception: As you touch the glass, sensory receptors in your hand and fingers detect the tactile sensations, relaying the information to the somatosensory cortex in the brain through the somatic nervous system. This allows you to perceive the shape, texture, and temperature of the glass.

Coordination: The somatic nervous system coordinates the muscle contractions and relaxations necessary for proper grip and control of the glass. It ensures that the muscles work together to provide the appropriate strength and dexterity required to hold and lift the glass without dropping it.

This example demonstrates the involvement of the somatic nervous system in voluntary movements and the sensory perception related to the physical action of picking up an object. It showcases the conscious control exerted over the skeletal muscles and the transmission of sensory information to the brain.

What Is The Somatic Nervous System Also Called?

The somatic nervous system is also known as the voluntary nervous system.