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Nervous System

The nervous system is the final piece in coordinating all the functions of each organ and system throughout the body. It allows for organisms to sense, process, and respond to stimuli. The two components of the nervous system are the central nervous system and the peripheral nervous system. 

Central Nervous System

The central nervous system consists of the brain and spinal cord. Together they process and generate responses for bodily functions. 

 

The brain is made up of:

  • Cerebrum:

    • The largest part of the brain divided into right and left hemispheres. Responsible for processing, reasoning, memory, voluntary movements, and emotion.

  • Cerebellum:

    • This is located behind the cerebrum at the back of the brain. It is involved in motor control (balance and coordinating muscle movement)

  • Brainstem:

    • Connects the brain to the spinal cord. Includes pons, midbrain, and medulla. It is responsible for life sustaining functions such as breathing, heart rate, and digestion. 

  • Diencephalon:

    • Located beneath the cerebrum and above the brainstem. This includes both the thalamus and hypothalamus. It is key to managing hunger, thirst, hormone control, and temperature regulation.

  • Limbic system:

    • Includes the hippocampus, amygdala, and hypothalamus as well. The limbic system is involved in emotions, memory, and motivation. 


 

The cerebrum is divided into four lobes:

 

1. Frontal lobe:

Front of brain behind the forehead

  • Thinking, planning, and problem solving

  • Motor cortex controls voluntary movements

  • Speech production in Broca’s area

  • Personality and impulses

2. Parietal lobe:

Found at the top and back of the brain

  • Contains somatosensory cortex for processing sensory information

  • Spatial awareness

  • Language processing in left side

3. Temporal lobe:

Sides of brain (temples)

  • auditory cortex for sound

  • Memory 

  • Wernicke’s area necessary for language comprehension

  • Emotional response through amygdala

4. Occipital lobe:

Located in back of brain above cerebellum

  • Visual processing

  • Visual perception

 

The left hemisphere of the brain is key to:

  • language processing

  • Problem solving

  • Details

  • Right side of body

 

The right hemisphere of the brain controls:

  • Creativity 

  • Spatial awareness

  • Emotions

  • Left side of body


 

Spinal cord:

 

The spinal cord runs from the brainstem to the rest of the back of the body. It is important for transmitting information and reflexes. 

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Peripheral Nervous System

The peripheral nervous system is the link between the CNS and the rest of the body including muscles, glands, and other organs. 

 

The PNS is made up of the somatic and the autonomic nervous system. 

 

The somatic nervous system controls voluntary movements and transmits sensory information to the brain utilizing motor and sensory neurons. 

 

The autonomic nervous system controls involuntary movements like digestion ,heart rate, and breathing. It is further separated into:

 

  1. Sympathetic: Flight and fight responses

  2. Parasympathetic: Rest and digest functions 

  3. Enteric: Regulates gastrointestinal system


 

Nervous tissue: 

 

Neurons:

Neurons transmit electrical signals across gaps between them known as synapses. A neuron looks like:

  • Cell body (soma): contains nucleus 

  • Dendrites: branched extensions to receive signals

  • Axon: transmit signals away from soma

  • Myelin sheath: fatty layer to speed transmission

  • Axon terminals: communicates with muscles, glands, or other neurons

 

Glial cells: 

Glial cells are support cells to nourish and protect neurons. Some protect the brain from harmful substances while others remove pathogens or form the myelin sheath around neurons for faster transmission. 

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Nervous System Disorders

Alzheimer's disease:

This is a neurodegenerative disorder that results in memory loss. It is believed to be due to the accumulation of amyloid plaques. 

Symptoms include: 

  • Memory loss

  • Difficulty with language and problem solving

  • Personality changes, mood swings

Treatments include encouraging mental activities, healthy eating, acetylcholinesterase inhibitors, and supportive care. 

 

Parkinson’s disease:

Neurodegenerative disorder caused by loss of dopamine producing neurons. 

Symptoms: 

  • Tremors

  • Difficulty walking

  • Speech and swallowing trouble

  • Muscle rigidity

Treatments include physical therapy, surgical implantation of electrodes, medications to increase dopamine. 

 

Epilepsy (seizure):

Recurring seizures due to electrical activity in the brain being abnormal. Can be triggered by brain injury or malformations. 

Symptoms: 

  • Jerking/shaking

  • Confusion 

  • Staring episodes

 

Stroke:

A stroke occurs when the blood supply to the brain is lost due to either a blood clot or blood vessel rupturing. The two forms of strokes are: 

Ischemic:

  • Blood clot

  • Clot busting drugs can be used as treatments

Hemorrhagic:

  • Ruptured blood vessel

  • Usually requires surgical intervention 

Symptoms: 

  • Numbness

  • Difficulty speaking 

  • Loss of coordination

  • Vision problems

 

FAST:

F: Face drooping

A: Arm weakness

S: Speech difficulty

T: Time to call 911
 

Migraine:

Recurrent headaches triggered by neurochemical imbalances in the brain. This can come from diet, stress, or environmental factors. 

Symptoms:

  • Severe throbbing

  • Sensitivity to light or sound

  • Nausea

Treatments include pain relief meds and lifestyle changes.

Nutrition

Omega-3 Fatty Acids:

Support structure and function of nerve cells. Reduce risk of Alzheimer's and other neurodegenerative diseases. 

  • Sources: Algal oil, flaxseeds, chia seeds, fatty fish, walnuts 

 

B vitamins:

B1: converts carbohydrates into energy for the nervous system 

B6: key role in production of neurotransmitters for mood

B12: crucial for production of myelin and nerve health 

Folate: Formation of RBCs and neural tubes

  • Sources: 

  1. B1: whole grains, beans, pork

  2. B6: poultry, fish, potatoes

  3. B12: meat, fish, eggs, dairy

  4. Folate: leafy greens and citrus fruits

 

Vitamin D:

Supports nerve growth and is linked to improvement in mood

  • Sources: sunlight, fatty fish, and mushrooms

 

Antioxidants:

Protect the brain from oxidative damage. Vitamin C is linked to dopamine and serotonin. Vitamin E protects nerve cells

  • Sources: 

  1. Vitamin C: citrus fruits, strawberries, broccoli

  2. Vitamin E: nuts, seeds, spinach, and avocado

 

Magnesium:

Magnesium is essential for proper nerve signaling

  • Sources: leafy greens, whole grains, nuts

 

Zinc:

Crucial to neurotransmission. Linked to memory, learning, and mood. 

  • Sources: Oysters, red meat, poultry, beans, nuts, seeds, and whole grains

 

Choline:

Choline is the precursor to acetylcholine which is essential to memory and learning. 

  • Sources: eggs, beef, broccoli

 

Amino Acids:

Tyrosine is involved in the production of neurotransmitters such as dopamine and epinephrine

Tryptophan is involved in producing serotonin

  • Sources: 

  1. Tyrosine: poultry, fish, dairy, and nuts

  2. Tryptophan: turkey, chicken, nuts, and cheese

 

Hydration:

Water is necessary to transport nutrients to the brain. Dehydration often leads to fatigue, headaches, and lack of concentration. 

Sources:

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