Lecture 02 - Fundamentals of Neurons & Neurotransmitters
🧠The nervous systems consists primarily of two classes of cells
○ neurons
○ glial cells
Glial Cells
🧠
considered theglueof the nervous system
○ binds the brain together to facilitate neural functioning and assist neurons in doing their jobs
🧠consist of various kinds
○ astrocyte cells
○ oligodendrocyte cells
■ schwann cells
○ microglial cells
Astrocytes
🧠found in thecentral nervous system
🧠helps create/compose theBlood Brain Barrier
○ keeps toxins out of the nervous system(preventingany hindrance to the brain function)
🧠plays crucial role in neural development
○ creates scaffolding in the brain
🧠plays a role in responding to injury
○ releases a chemical response to hinder the injury
Oligodendrocyte
🧠found in thecentral nervous system
🧠insulates the axons of neurons (the info highway)
○ insulates throughmyelination
■ wrappingmyelin sheathson the axons
○ this ensures the signal reaches the end of axon
Schwann Cells
🧠exact samefunctions asoligodendrocyte cells, butare found in neurons outside of the central nervous system
○ found in the peripheral nervous system(basicallyeverything except the brain and spine)
Microglial Cells
🧠found in thecentral nervous system
🧠“scavenger neurons”
○ their function is to eat/dispose of dead or dying neurons
Neurons
🧠
the communicative unit of the nervous system
○ transmit signals from one part of the nervous system to another
🧠diff kinds
○ motor neurons- carry motor info(i.e. how each partof the body should move)
, ○ sensory neurons- carry exclusive sensory info)
■ certain ones carryonlyvisual info, certain onescarryonlyauditory info, etc.
○ interneurons- the powerhouse of the brain, as ithelps compute info to guide behaviour
■ the classification of most neurons (90%)
■ process a wide variety of info
● memory
● language
● attention
● etc
Action Potential
🧠
action potential= trigger for a signal to be sentthrough a neuron
🧠
the signal is triggered by get excited by surrounding neurons
○ the action potential is triggered when a certain positivity threshold is met
🧠the number of signals sent by neurons mean a stimuli is more
○ i.e. louder, brighter, more painful, etc..
🧠resting potential = -70
🧠action potentials = spikes in positivity
Propagation of the Signal Down the Axon
🧠
the signal starts of in theaxon hillock(l ike thehead of the neuron)
🧠
travels through the axon
○ passes through the myelin sheaths andnodes of ranvier
■ gaps between the sheaths that regenerate action potential as the signal weakens as it travels
down the axon
Myelin Degradation -Multiple Sclerosis (MS)
🧠
progressive myelin degradation, presumably due to an autoimmune disorder
🧠
caused by the myelin being attacked by the immune system (i.e. autoimmune disorders)
○ damage to myelin could cause damage to the axon
🧠it’s neurodegenerative (occurs over time)
🧠without myelin signals can’t transfer within the neuron
🧠symptoms
○ impact to memory -forgetfulness
○ impacts the senses
○ impacts motor pathways and hinders capabilities of moving (i.e. walking becomes impaired)
🧠the symptoms are heterogenous
○ differ across individuals depending on where the MS starts degradation of the myelin
🧠highest rates of MS in the world are in Canada
○ this is due to the Northern geography and exposure to sunlight and temperatures
Motor Neuron Disease -Amyotrophic Lateral Sclerosis(ALS)
🧠
a rapidly progressing upper and lower motor disease
○ results in death
🧠motor neurons get attacked
🧠The nervous systems consists primarily of two classes of cells
○ neurons
○ glial cells
Glial Cells
🧠
considered theglueof the nervous system
○ binds the brain together to facilitate neural functioning and assist neurons in doing their jobs
🧠consist of various kinds
○ astrocyte cells
○ oligodendrocyte cells
■ schwann cells
○ microglial cells
Astrocytes
🧠found in thecentral nervous system
🧠helps create/compose theBlood Brain Barrier
○ keeps toxins out of the nervous system(preventingany hindrance to the brain function)
🧠plays crucial role in neural development
○ creates scaffolding in the brain
🧠plays a role in responding to injury
○ releases a chemical response to hinder the injury
Oligodendrocyte
🧠found in thecentral nervous system
🧠insulates the axons of neurons (the info highway)
○ insulates throughmyelination
■ wrappingmyelin sheathson the axons
○ this ensures the signal reaches the end of axon
Schwann Cells
🧠exact samefunctions asoligodendrocyte cells, butare found in neurons outside of the central nervous system
○ found in the peripheral nervous system(basicallyeverything except the brain and spine)
Microglial Cells
🧠found in thecentral nervous system
🧠“scavenger neurons”
○ their function is to eat/dispose of dead or dying neurons
Neurons
🧠
the communicative unit of the nervous system
○ transmit signals from one part of the nervous system to another
🧠diff kinds
○ motor neurons- carry motor info(i.e. how each partof the body should move)
, ○ sensory neurons- carry exclusive sensory info)
■ certain ones carryonlyvisual info, certain onescarryonlyauditory info, etc.
○ interneurons- the powerhouse of the brain, as ithelps compute info to guide behaviour
■ the classification of most neurons (90%)
■ process a wide variety of info
● memory
● language
● attention
● etc
Action Potential
🧠
action potential= trigger for a signal to be sentthrough a neuron
🧠
the signal is triggered by get excited by surrounding neurons
○ the action potential is triggered when a certain positivity threshold is met
🧠the number of signals sent by neurons mean a stimuli is more
○ i.e. louder, brighter, more painful, etc..
🧠resting potential = -70
🧠action potentials = spikes in positivity
Propagation of the Signal Down the Axon
🧠
the signal starts of in theaxon hillock(l ike thehead of the neuron)
🧠
travels through the axon
○ passes through the myelin sheaths andnodes of ranvier
■ gaps between the sheaths that regenerate action potential as the signal weakens as it travels
down the axon
Myelin Degradation -Multiple Sclerosis (MS)
🧠
progressive myelin degradation, presumably due to an autoimmune disorder
🧠
caused by the myelin being attacked by the immune system (i.e. autoimmune disorders)
○ damage to myelin could cause damage to the axon
🧠it’s neurodegenerative (occurs over time)
🧠without myelin signals can’t transfer within the neuron
🧠symptoms
○ impact to memory -forgetfulness
○ impacts the senses
○ impacts motor pathways and hinders capabilities of moving (i.e. walking becomes impaired)
🧠the symptoms are heterogenous
○ differ across individuals depending on where the MS starts degradation of the myelin
🧠highest rates of MS in the world are in Canada
○ this is due to the Northern geography and exposure to sunlight and temperatures
Motor Neuron Disease -Amyotrophic Lateral Sclerosis(ALS)
🧠
a rapidly progressing upper and lower motor disease
○ results in death
🧠motor neurons get attacked
