The Nervous System

Introduction:

  • the Nervous system is the most complex system in our body, it serves as the body's control and communications center
  • this system detects, interprets, and responds to changes in internal and external conditions
  • it integrates countless bits of information and generates appropriate reactions by sending electrochemical impulses through nerves to effector organs (muscles/glands)
  • two major divisions: central & peripheral nervous system
  • without the nervous system NO other systems would be able to function

Central Division:

  • the "command station"
  • made up of the brain and spinal cord
  • the main function of the central nervous system is to process sensory information and determine what the appropriate reaction is
  • neurons of the central nervous system only interact with other neurons and are called interneurons
  • unlike sensory and motor neurons, interneurons both send and receive signals to and from other neurons

Peripheral Division:

  • functions to gather sensory information and to control the actions of our bodies
  • the peripheral nervous system includes two basic types of neurons: sensory & motor neurons
  • sensory neurons are neurons that collect sensory input and send it to the brain
  • motor neurons are neurons that transmit signals to responsive tissues.
  • contains two systems: somatic & autonomic, at times these two system work in opposition
Somatic
  1. The somatic system carries signals about moving the head, trunk, and limbs.
  2. First, its sensory axons deliver information from receptors in the skin, skeletal muscles, and tendons to the central nervous system.
  3. Then, its motor axons deliver the commands from the brain and spinal cord to the skeletal muscles.

Autonomic
  1. provides almost every organ with a double set of nerves-the sympathetic and parasympathetic
  2. sympathetic system activates & prepares body for vigorous muscular activity, stress and emergencies
  3. parasympathetic system lowers activity, operates during normal situations, permits digestion and conservation of energy 

Neurons, Brain, & Spinal Cord:

  • neurons transmit electric signals like electric wire
  • input channels receive information from other neurons/sensory cells (these are cells that receive information from the environment)
  • neurons send messages along the axon to other neurons/ directly to muscles or glands
  • in order to transmit signals neurons must be linked to each other
  • the brain- receives, integrates, stores, and retrieves sensory information
  • the spinal cord- expressway for signals between the brain and the peripheral nervous system

The SpineThe spinal cord is considered to be an "information highway", which connects the peripheral nervous system to the brain. It is protected by 31 vertebrae. At each segment of bone a pair of spinal nerves branch out. The spinal cord receives information from sensory and motor neurons. Sensory receptors send information along sensory neurons to the spinal cord. From here it is passed via interneurons to motor neurons that lead to muscles in the body. This causes movement. Sensory neurons can also send information through the spinal cord into the brain stem, to then be processed by the thalamus, the sensory switchboard of the brain (except for smell).


Overview of Spinal Cord DisordersThe causes for spinal cord disorders include injuries, infections, a blocked blood supply, and compression by a fractured bone or tumor. The muscles can be become weak or paralyzed and sensation can be abnormal or lost. If possible the conditioned will be corrected by a trained professional. Often, in order to recover as much function as possible, rehabilitation is needed.
Injuries to the Spinal Cord.
  • Injury
  • Infection
  • Compression
Disorders include the Spinal Cord:
  • fluid-filled cavities
  • blockage of the blood supply
  • inflammation
  • tumors
  • abscesses
  • bleeding
  • vitamin b12 or copper deficiency
  • HIV
  • multiple sclerosis
  • syphilis
Symptoms
  • weakness
  • loss of sensation
  • changes in reflexes
  • loss of bladder control
  • loss of bowel control
  • erectile dysfunction
  • paralysis
  • back pain
Picture
Image Source: http://www.questgarden.com/02/58/1/051113190125/images/nueron-l.jpg http://ak.picdn.net/shutterstock/videos/5366036/preview/stock-footage-medical-animation-of-the-human-nervous-system.jpg

Diseases of the Nervous System:

Nerve Disorders
  • stroke
  • transient ischemic attack (TIA)
  • subarachnoid hemorrhage
  • subdural hemorrhage and hematoma
  • extradural hemorrhage
Functional Difficulties
  • epilepsy
  • Parkinson's disease
  • multiple sclerosis
  • amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease
  • Huntington's chorea
  • Alzheimer's disease

The nervous system is quite possibly the most vital and oddest part of the human body.  While other systems may claim that they hold the most vital spot, they are sadly mistaken.  Every part of our nervous system, while not every part of this system is "necessary"(you would be surprised at the sheer amount of brain damage someone can live through) all of it is useful. The nervous system as a whole is what makes us the super cool sentient life that we are, and not just a meat sack of automatic functions.  Now, that said there is quite a few places where this structure can mess up.  Whether it is from birth, or disease, or physical trauma, some pretty weird disorders can come and pop up.

General Information About Nervous System Disorders

      - Nervous system disorders can come from abnormalities with one's nervous system, this can be brought on by: trauma, infections, degeneration, structural defects, tumors, blood flow disruption, and auto immune disorders.  
      - These disorders usually have some of these symptoms: odd persistent headaches, loss of feeling/tingling, weakness, loss of vision, memory loss, impaired mental ability, lack of coordination, muscle rigidity, tremors & seizures, pain, muscle wasting, and slurred speech.
     - There are also two kind of nervous system disorders when concerning the brain.  Abnormalities that come from odd development of the brain prior to birth is a neurological disorder since it concerns how you are neurologically set up, this includes disorders such as schizophrenia and the autism spectrum.  Disorders that are gained from some form of damage during life are mental disorders. This includes things such as depression.

  • Parkinson's Disease
               - A nervous system disease that causes gradual deterioration of ones motor skills (less facial expressions, slower walking, less arm movement, slurred speech, etc.)
               -The disease usually starts with slight tremors in the hand.  The effects are gradual and worsen as they go on.  As of right now there is no cure, however there does exist medication that lessons symptoms and halts the disease's progress. So that's sort of good.
  • Bell's Palsy
          - A Disease that causes intense amounts of facial paralysis to half of your face (it makes you unable to feel or move half of your face).  Also you can't close your eye on that side.
          - The disease does not have a known cause, however there is medication to take for it and it is possible to recover from although it is completely capable of causing permanent damage to your face muscles/ nerves.

  • Cerebral Palsy

        - Not to be confused with bell's palsy.  Cerebral Palsy is a disorder that comes from experiencing physical head trauma around and during the time of ones birth.  
       - The disorder has a large amount of possible symptoms such as: disorder of movement, limited motor skills, limited mental capacity/capabilities, fixed abnormalities from limb contractions (limbs stuck at weird angles), epilepsy, visual impairment, squint, reduced hearing, and behavioral problems.  

  • Motor Neuron Disease

         - Deterioration of someones motor system during middle age.  It is a disease that is inherited from parents.
         - Affects one's spinal cord and specific nuclei in the brain.
         - Causes muscle weakness and wasting.

  • Epilepsy Seizures

      - General seizures: all areas of the brain are involved.
       - Symptoms are: opened eyes, odd sounds or crying out, possible lack of breath, loss of urine(through excretion), a loss of consciousness followed by a gradual regaining of it, and confusion following the moment.

  • Multiple Sclerosis

          - Affects are commonly seen in young and middle aged adults.
          - The disorder is brought about through damage to the coating around nerve cells, this impairs the function of the nerve.
         - The common symptoms one would experience from this are shaking of the limbs, involuntary eye movement, problems with pronunciation, and spastic weakness.

  • Sciatica

          - This common condition is caused by the damaging or compressing of one's nerves or nerve roots. this form of injury can also happen very suddenly
          - what this then causes is a general pain felt in the back and the legs, as well as stiffness for the back, as well as numbness and weakness in legs.
Source: https://www.youtube.com/watch?v=RlUPCNLSJIY

References:

Balingit, Angelica. “Liver: Anatomy, Definition, Symptoms, and More.” Healthline, 30 May 2018, http://www.healthline.com/human-body-maps/liver. Accessed 9 June 2022.
Hoffman, Matthew. “The Esophagus (Human Anatomy): Picture, Function, Conditions, and More.” WebMD, 10 July 2020, https://www.webmd.com/digestive-disorders/picture-of-the-esophagus. Accessed 19 November 2022.
​Hoffman, Matthew. “Liver (Anatomy): Picture, Function, Conditions, Tests, Treatments.” WebMD, 23 June 2021, http://www.webmd.com/digestive-disorders/picture-of-the-liver. Accessed 19 November 2022.
“Watch Why This Taste Map Is Wrong | Currents.” WIRED, 30 March 2020, https://www.wired.com/video/watch/taste-map. Accessed 19 November 2022.
Wedro, Benjamin. “Liver Anatomy & Function Tests, Disease Symptoms & Causes.” MedicineNet, http://www.medicinenet.com/liver_anatomy_and_function/article.htm. Accessed 28 November 2021.
Paola Arias