Anatomic.us > Nervous System

Nervous System

Systema nervosum is the Latin pronunciation for human Nervous System. Nervous System of the body is comprised of Brain, Spinal Cord, Sensory Organs and all of the Nerves that connect these organs to the rest of the body. All these organs function together for the control of body and communication of its parts. Central Nervous System is the control center of the body and is made of Brain and Spinal Cord. This part is responsible for information evaluation and making the decisions afterwards. Monitoring the outside conditions and sending the relative information to Central Nervous System (CNS), is carried out by sensory nerves and sense organs of Peripheral Nervous System (PNS). To regulate the functions of the Glands, Organs and Muscles Efferent Nerves of the PNS carry signals from the control centers.

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Nervous System

h4 dir="ltr">ANATOMY:

Nervous system of the body is divided into 7 anatomical sections for proper understanding, which are as follows.

  • Nervous Tissues:

Mainly the Nervous System is comprised of Nervous Tissues made of two classes of cells i.e.

  • Neurons, also called Nerve Cells, communicate within the body by transmission of Electrochemical Signals. They are different from other cells because of their extended processes arising out of the main cell body, known as Axons. They send signals to other Neurons in the body. They possess small tree like structures called Dendrites that are meant for picking up the environmental stimuli. There are three types of neurons:

  • Afferent Neurons, also called Sensory Neurons, send sensory signals from the Receptors of body to the Central Nervous System.

  • Efferent Neuron, also called Motor Neurons, cause the transmission of signals from Central Nervous System to Effectors of body like muscles and glands.

  • Interneurons form a complex network within the CNS to evaluate the information from the Afferent Neurons and direct it to Efferent Neurons.

 

  • Neuroglia:

Neuroglia, also called Glial Cells, function for helping the Nervous System. Every Neuron is surrounded from 6 to 60 Neuroglia that provide protection, feeding and insulation.

 

  • Brain :

Brain is a soft organ, weighing 3 pounds, situated inside Cranial Cavity. There are approximately 100 billion Neurons in the brain. Brain along with Spinal Cord forms the Central Nervous System, which is responsible for processing information and generating responses. Brain has vast number of Higher Mental and Lower Body functions, which are as follows.

Higher mental functions like

  • Consciousness

  • Memory

  • Planning

  • Voluntary actions

Lower body functions like

  • Respiration

  • Heart Rate

  • Blood Pressure

  • Digestion

 

  • Spinal Cord:

Spinal Cord is a long thin mass of bundled neurons running inside the vertebral column. In the Lumbar region it separates into individual nerves called Cauda Equina which continues into Sacrum and Coccyx. It has two functional regions, including:

  • White Matter: It functions to conduct Nerve signals from brain to body.

  • Grey Matter: it integrate reflexes to stimuli.

 

  • Nerves:

Nerves are bundle of Axons present in the Peripheral Nervous System acting as a passage for carrying signals between brain, spinal cord and rest of the body. The anatomy of the Nerve is explained in three steps i.e.

  • Axon is encapsulated in a sheath called Endoneurium.

  • Axons of a Nerve are wrapped, in form of a bundle, in a sheath of connective tissues called Perineurium. This bundle is called Fascicle.

  • Many fascicles are wrapped in another sheath of connective tissues called Epineurium forming a whole Nerve.

 

  • Meninges:

Protective coverings of the Central Nervous System are called Meninges. They are of three types:

  • Dura Mater is the thickest and superficial layer of Meninges. Containing tough Collagen Fibers and Blood Vessels, it is comprised of dense irregular tissues. It protects the Central Nervous System from external damage.

  • Arachnoid Mater is thinner and delicate than Dura Mater and lines it. It has thin fibers connecting it to the Pia Mater.

  • Pia Mater is a layer of thin delicate tissues on outside of brain and spinal cord. It feed the Nervous tissues of Central Nervous Center by its blood vessels.

 

  • Cerebrospinal Fluid:

A clear fluid surrounds the space of Central Nervous System. This fluid is called Cerebrospinal Fluid. Special structures from blood plasma called Choroid Plexuses forms this fluid. This fluid flows between hollow spaces of brain called Ventricles and small cavity of the Spinal Cord called Central Canal. It’s important functions are as follows.

  • Absorption of shocks between brain and skull and spinal cord and vertebrae. This absorption protects CNS from blows and sudden changes like car accidents.

  • Through the effect of bouncy it reduces the apparent weight of Brain and Spinal Cord. This allows the blood vessels of Brain to remain open and protect the nervous tissues from crushing under its own weight.

  • Maintenance of Chemical Homeostasis within CNS.

  • Removal of waste products formed during cellular metabolism in Nervous tissues.

 

  • Sensory Organs:

Body’s sensory organs are parts of CNS. Special organs are Eyes, Taste Buds and Olfactory Epithelium that help in detection of special senses like Vision, Smell, Taste, Hearing and Balance. This information of senses is transmitted from Sensory Receptors of the body to CNS for processing and integration through Afferent Neurons.

 

FUNCTION:

Main functions of the Nervous System are as follows.

  • Sensory: Sensory function of the Nervous System is the collection of information from Sensory Receptors, monitoring the internal and external conditions of body. By afferent Neurons these signals are transmitted to Central Nervous System for processing.

  • Integration: Integration function is to process Sensory Signals transmitted to Central Nervous System at any time. There these signals are evaluated then used for decision making, discarded or kept in memory depending upon importance. Integration process is carried out in Gray Matter of Brain and Spinal Cord and the necessary function is carried out by Interneurons.

  • Motor: After the evaluation of sensory information and the necessary decision made in the Interneurons, Efferent Neurons or Motor Neurons are stimulated. Then these Motor Neurons take the information from Gray Matter to Effector Cells which may be Smooth, Cardiac or Skeletal Muscle Tissue or Glandular tissues. Hormones are secreted from these Effectors for response to stimulus.

CLINICAL SIGNIFICANCE:

Nervous System disorders are defined by term Neuropathy. Nervous system disorders are divided according to its two parts i.e.

  • Central Nervous System:

Some of the Central nervous System disorders are as follows.

  • Catalepsy

  • Epilepsy

  • Meningitis

  • Migraine

  • Huntington’s Disease

  • Alzheimer’s Disease

  • Parkinson’s Disease

  • Tourette’s Disease

 

  • Peripheral Nervous System:

Common of Peripheral Nervous System disease is Neuritis. The condition is caused by the Inflammation of Nerve symptoms of which are as follows.

  • Pain

  • Weakness

  • Numbness

  • Paralysis

  • Anesthesia

  • Disappearance of reflexes


h4 dir="ltr">ANATOMY:

Nervous system of the body is divided into 7 anatomical sections for proper understanding, which are as follows.

  • Nervous Tissues:

Mainly the Nervous System is comprised of Nervous Tissues made of two classes of cells i.e.

  • Neurons, also called Nerve Cells, communicate within the body by transmission of Electrochemical Signals. They are different from other cells because of their extended processes arising out of the main cell body, known as Axons. They send signals to other Neurons in the body. They possess small tree like structures called Dendrites that are meant for picking up the environmental stimuli. There are three types of neurons:

  • Afferent Neurons, also called Sensory Neurons, send sensory signals from the Receptors of body to the Central Nervous System.

  • Efferent Neuron, also called Motor Neurons, cause the transmission of signals from Central Nervous System to Effectors of body like muscles and glands.

  • Interneurons form a complex network within the CNS to evaluate the information from the Afferent Neurons and direct it to Efferent Neurons.

 

  • Neuroglia:

Neuroglia, also called Glial Cells, function for helping the Nervous System. Every Neuron is surrounded from 6 to 60 Neuroglia that provide protection, feeding and insulation.

 

  • Brain :

Brain is a soft organ, weighing 3 pounds, situated inside Cranial Cavity. There are approximately 100 billion Neurons in the brain. Brain along with Spinal Cord forms the Central Nervous System, which is responsible for processing information and generating responses. Brain has vast number of Higher Mental and Lower Body functions, which are as follows.

Higher mental functions like

  • Consciousness

  • Memory

  • Planning

  • Voluntary actions

Lower body functions like

  • Respiration

  • Heart Rate

  • Blood Pressure

  • Digestion

 

  • Spinal Cord:

Spinal Cord is a long thin mass of bundled neurons running inside the vertebral column. In the Lumbar region it separates into individual nerves called Cauda Equina which continues into Sacrum and Coccyx. It has two functional regions, including:

  • White Matter: It functions to conduct Nerve signals from brain to body.

  • Grey Matter: it integrate reflexes to stimuli.

 

  • Nerves:

Nerves are bundle of Axons present in the Peripheral Nervous System acting as a passage for carrying signals between brain, spinal cord and rest of the body. The anatomy of the Nerve is explained in three steps i.e.

  • Axon is encapsulated in a sheath called Endoneurium.

  • Axons of a Nerve are wrapped, in form of a bundle, in a sheath of connective tissues called Perineurium. This bundle is called Fascicle.

  • Many fascicles are wrapped in another sheath of connective tissues called Epineurium forming a whole Nerve.

 

  • Meninges:

Protective coverings of the Central Nervous System are called Meninges. They are of three types:

  • Dura Mater is the thickest and superficial layer of Meninges. Containing tough Collagen Fibers and Blood Vessels, it is comprised of dense irregular tissues. It protects the Central Nervous System from external damage.

  • Arachnoid Mater is thinner and delicate than Dura Mater and lines it. It has thin fibers connecting it to the Pia Mater.

  • Pia Mater is a layer of thin delicate tissues on outside of brain and spinal cord. It feed the Nervous tissues of Central Nervous Center by its blood vessels.

 

  • Cerebrospinal Fluid:

A clear fluid surrounds the space of Central Nervous System. This fluid is called Cerebrospinal Fluid. Special structures from blood plasma called Choroid Plexuses forms this fluid. This fluid flows between hollow spaces of brain called Ventricles and small cavity of the Spinal Cord called Central Canal. It’s important functions are as follows.

  • Absorption of shocks between brain and skull and spinal cord and vertebrae. This absorption protects CNS from blows and sudden changes like car accidents.

  • Through the effect of bouncy it reduces the apparent weight of Brain and Spinal Cord. This allows the blood vessels of Brain to remain open and protect the nervous tissues from crushing under its own weight.

  • Maintenance of Chemical Homeostasis within CNS.

  • Removal of waste products formed during cellular metabolism in Nervous tissues.

 

  • Sensory Organs:

Body’s sensory organs are parts of CNS. Special organs are Eyes, Taste Buds and Olfactory Epithelium that help in detection of special senses like Vision, Smell, Taste, Hearing and Balance. This information of senses is transmitted from Sensory Receptors of the body to CNS for processing and integration through Afferent Neurons.

 

FUNCTION:

Main functions of the Nervous System are as follows.

  • Sensory: Sensory function of the Nervous System is the collection of information from Sensory Receptors, monitoring the internal and external conditions of body. By afferent Neurons these signals are transmitted to Central Nervous System for processing.

  • Integration: Integration function is to process Sensory Signals transmitted to Central Nervous System at any time. There these signals are evaluated then used for decision making, discarded or kept in memory depending upon importance. Integration process is carried out in Gray Matter of Brain and Spinal Cord and the necessary function is carried out by Interneurons.

  • Motor: After the evaluation of sensory information and the necessary decision made in the Interneurons, Efferent Neurons or Motor Neurons are stimulated. Then these Motor Neurons take the information from Gray Matter to Effector Cells which may be Smooth, Cardiac or Skeletal Muscle Tissue or Glandular tissues. Hormones are secreted from these Effectors for response to stimulus.

CLINICAL SIGNIFICANCE:

Nervous System disorders are defined by term Neuropathy. Nervous system disorders are divided according to its two parts i.e.

  • Central Nervous System:

Some of the Central nervous System disorders are as follows.

  • Catalepsy

  • Epilepsy

  • Meningitis

  • Migraine

  • Huntington’s Disease

  • Alzheimer’s Disease

  • Parkinson’s Disease

  • Tourette’s Disease

 

  • Peripheral Nervous System:

Common of Peripheral Nervous System disease is Neuritis. The condition is caused by the Inflammation of Nerve symptoms of which are as follows.

  • Pain

  • Weakness

  • Numbness

  • Paralysis

  • Anesthesia

  • Disappearance of reflexes

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