Glial Cells

Oligodendrocytes

  • Wrap CNS axons in myelin

Microglia

  • Brain’s primary immune cell/immune system for the brain

  • Microscopically: has thorny processes

Astrocytes

  • Make up and maintain the blood brain barrier (protects the brain from harmful substances)

  • Keeps toxins like heavy metals and pesticides out of brain tissue

  • Most abundant of all glial cells

Ependymal cells

  • Line the ventricles of the brain (3rd and 4th)

  • Produce cerebral spinal fluid

PNS

Schwann cells

  • Similar to Oligodendrocytes, makes myelin and warps the axon

Satellite cells

  • Provide structure and metabolic/nutritional support for neurons in the PNS

Neuron characteristic

  • Live an extremely long time (about 100 years)

  • Contain a nucleus

  • Very high metabolic rate/demands because the brain burns a lot of fuel, need and crave glucose and oxygen = ATP

  • Do not undergo mitosis (amitotic)

  • When the cell body/soma/perikaryon receives enough stimulus through its dendritic spine, the cell body gets so excited that it reaches its threshold, when it reaches the threshold, an action potential is generated

Action potential characteristics

  • All or none event: if the cell body reaches threshold it has no other options, if it does not an action potential is not generated (11:50)

  • Once an action potential is generated, it cannot be stopped, it leaves the cell body and travels down the entire length of the axon, reaches the synaptic cleft, neurotransmitters migrate across the synaptic cleft and possibly stimulate another action potential

Neurological terms

  • Axons and neural fibers wrapped in myelin/lipids; because myelin is made of fat, it appears as white = white matter

  • Cell bodies and Non myelinated/no lipid coating will appear on imaging as grey matter (processing of information)

  • 3 different types of neurons classified by processes they posses:

    • Unipolar: 1 process

    • Bipolar: 2 processes

    • Multipolar: many processes

  • 99% of neurons are interneurons: relay information from one neuron to another or from 1 neuron to a target end organ

Lobes of the brain

  • Frontal lobe: responsible for executive functioning (rational thought, deductive reasoning, impulse control)

  • Parietal lobes: responsible for speech, reading, and language processing

  • Occipital lobe: processes sight, 1/3 of cranial nerves are dedicated to vision

  • Temporal lobes: house memory (short term and long term), cochlear nerve travels through temporal nerve, this is why sounds trigger intensely vivid memories

Insula

  • between parietal lobes, responsible for many autonomic functions, houses feelings and emotions, 25% larger in females

CTE (chronic traumatic encephalopathy)

  • only diagnosed post-mortem, develops after repetitive head/brain trauma, receptive brain trauma causes neurons to die

  • Chemical makeup of what’s inside the neuron is toxic to the outside of the neuron, when a neuron dies and spills this toxin, the material can cause those cells to die

  • Leads to rage depression, suicidal tendencies

Saltatory conduction (30 min)

  • in order to speed up conduction velocity electrical impulses can jump from node to node, impulse travels from node to node

Multiple sclerosis (MS)

  • most common demyelinating disease, myelin is peeled off the axon, impulse will become slower and weaker (lower amplitude)

  • 92% of people are right-handed, means they’re left brain dominant

When the sympathetic nervous system is constantly under control

Chronic sympathetic activation

  • Body is constantly sympathetically activated

  • Stimulates adrenal glands, adrenaline goes up, insulin goes up, cortisol goes up

  • Symptoms: headaches, anxiety, depression, high blood pressure, reduced sex drive, immunosuppressed, causes significant increase in risk of cancer, triggers digestive disorders (IBS, diverticulitis, Crohn’s disease), weight gain

How to combat this

  • Meditation, exercise, daylight, hydration, sleep, breathing

  • Average screen time: 9 hrs

  • When screen time exceeds 4-5 hours, brain waves change, depression, anxiety §

Enteric nervous system (ENS)

  • Mind/brain-gut connection

  • Gut feeling/intuition

  • Oldest part of the nervous system

  • Completely geared towards survival

  • Communicates bidirectionally to the brain and out to the digestive tract at the same time

  • Body’s second brain

  • Controls digestion, motility (peristalsis)

  • Does all of this automatically from the central nervous system (instinctive)