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Advanced Neurophysiology (1st Year University notes)
Anatomy of Neuron:
• Soma/Cell body - Body of the neuron containing the nucleus to transmit signal to
Axon Hillock
• Dendrites - Branches of the Soma to pick up the action potential
• Axon Hillock - Joining Cell body to the Axon and start of Local current flow
• Axon • Axon Terminal - End of the Axon which connects to target cells
• Schwann cells - Cells forming Myelin Sheath in PNS axon
• Nodes of Ranvier - Gaps in between Myelin Sheaths
• Synapse - Place where Axon Terminal is close to touching the target cell
CNS neurons:
• Neurons start as Neural Stem Cells
• Stem Cells differentiate into Neuroblasts
• Neuroblasts move away to become a neuron by developing into a Soma and
extending towards the Target cells the Axon
Uni, Bi,Multi and pseudounipolar Neurons:
• Unipolar - Consists of Soma and Axon end
• Bipolar - Consists of Soma, Axon end and 1 Dendritic end
• Multipolar - Consists of Soma, Axon end and multiple Dendritic ends
• Pseudo-unipolar - Has Soma, Peripheral Axon end and Central Axon
Neuron Function overview:
• Process and transmit information
• Impulses input through the Dendrites
• Impulse transmitted to Axon with membrane potential changes known as Graded
Potential
• If the Graded Potential at the trigger zone exceeds threshold, action potential is
passed through the Axon
• Axon Terminal secretes Neurotransmitters through Synapses to target cells
Multiple Functional types of Neurons:
• Pseudo-unipolar neurons have Afferent, or Sensory (as it is information about a
stimulus), neurons that work to get information from PNS to CNS through
• In other neurons, information is being sent from CNS to PNS, away from CNS, so
they are known as Efferent Neurons
• Efferent Neurons are split into Somatic Motor neurons (Skeletal Muscles) and
Autonomic neurons (Smooth and Cardiac Muscles as well as Gland cells)
• Most CNS neurons are known as Interneurons as they connect neurons to other
neurons
Saltatory Conduction:
•

Axons are designed to have low resistance though has high resistance insulation so
potential does not leak outside
• However, if the whole of the Axon is insulated, the impulse at the Terminal will be
weak as it dissipates passing through
• Gaps as therefore found between myelin sheaths, known as Node of Ranviers
• Voltage-gated channels are found in the Nodes of Ranvier to help boost the signal
when the dissipated impulse reaches it
• There are many Nodes of Ranvier in one Axon to ensure that the impulse at the
Terminal is high enough to trigger anything at the end
• This process is known as Saltatory Conduction
--------------------------------------------------------------------------------------------------------------------------Types of Nervous system:
• CNS - Brain and Spinal Cord
• PNS - Everything around the CNS

Advanced Neurophysiology (1st Year University notes)
Brain:
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Top half - Cerebrum
2 Hemispheres - Cerebral Hemispheres
Middle of the brain contains the brainstem; divided into the Midbrain, Pons and
Medulla
• The back of the brain, connected to the Brainstem - Cerebellum
Developing Brain:
• Front - Forebrain; becomes the Cerebrum
• Middle - Midbrain; becomes the Midbrain
• Back - Hindbrain - becomes the rest of the brain
Peripheral Nervous System:
• Consists of Nerves (containing Axons of neurons) and Ganglia (containing Soma of
neurons)
• Afferent/Sensory Neurons carry the impulses from the PNS to the CNS
• Efferent Neurons carry impulses away from the CNS to the PNS
Types of Nerves:
• Divided into Cranial Nerves or Spinal Nerves
Cranial Nerves:
• Nerves that exit the brain
• Come in pairs; 12 pairs in total
• Visible when looking at the bottom cross-section of the brain
• String shaped
Spinal Nerves:
• Nerves that exit the Spinal Cord
• Comes in pairs; 31 pairs in total
• Formed from 2 Spinal Nerve Roots, one at the front and one at the back
• Afferent neurons travel through the back root to the Spinal Cord
•
Efferent Neurons travel through the front roots
• Nerves keep branching and become gradually microscopic until they reach distal
parts of the body from the CNS
Functions:
• Split into Basic functions and Complex functions
• Syndromes - Patterns of Abnormalities
• Syndromes for the nervous system is common due to neurological and Psychiatric
disorders
Basic Functions:
• Performed by larger CNS and PNS
• Motor - Skeletal Muscle control
• Sensory - Senses
• Automatic - Reflex
Higher functions:
• Performed by parts of the brain
• Cognition - Thinking functions of the brain
• Emotions - Feelings
• Consciousness - Awareness of being a person
--------------------------------------------------------------------------------------------------------------------------• Neurotransmitters are molecules that communicate information between neurons and
target cells
Categories of Neurotransmitters:
• Amino Acid - Contain amine and Carboxylic group
• Peptide - Chains of Amino Acids
• Monoamine (Biogenic) - Contain Amine group connected to an aromatic group via a
2-Carbon chain
• Catecholamine - Subgroup with a Catechol group (Benzene ring with 2 OH
groups)

Advanced Neurophysiology (1st Year University notes)
• Other categories
Amino Acid Neurotransmitters:
• Important ones; Glutamate, GABA and Glycine
• Conduct most functions of the Nervous System
• Glutamate is the most common type of Excitatory Neurotransmitter as it usually
depolarises Target Cells to excite them
• GABA and Glycine are the most common Inhibitory Neurotransmitters
Monoamines Neurotransmitters:
• Examples are Serotonin, Histamine, Dopamine, Epinephrine and Norepinephrine
• Important functions in the brain involved with Attention, Cognition, emotion
Peptide Neurotransmitters:
• A sub group known as Opioids which play a role in perception and pain
• An example is Endorphin
Other Neurotransmitters:
• Acetylcholine - Has functions in the CNS but secreted in PNS autonomic systems
--------------------------------------------------------------------------------------------------------------------------Types of Neurotransmitter Receptors:
• Ionotropic Receptors
• Metabotropic receptors
Ionotropic Neurotransmitter Receptors:
• Ligand-gated ion channels
• When ligands bind to Neurotransmitter, they open and allow certain ions to pass
• When activated, they induce graded potentials which have an effect on potential of
the membrane
• If the ion influx is Na or Ca ions, the Postsynaptic neuron will get activated to cause a
depolarisation
• If the ion influx is Cl or K ions, it causes inhibition
• Cl ions bring negative charges in whilst K ions will usually exit the neuron
Metabotropic Neurotransmitter Receptors:
• Second Messengers activated when Neurotransmitters bind onto the receptor
• They can affect behaviour of ion channels, activate proteins or genes
• Response is slower than Ionotropic Receptors though the effects are larger and more
widespread due to amplification of Second Messengers
--------------------------------------------------------------------------------------------------------------------------• A synapse is a structure that permits a neuron to pass electrical/chemical impulses to
another neuron/target cell or effector
Types of Synapses:
• Chemical - involves a gap where neurotransmitters are released
• Electrical - cells are physically connected with gap junctions allowing the inside of the
two cells to interact
Axon Terminal-Target cell Synapse:
• Presynaptic neuron = Axon Terminal
• Postsynaptic Neuron = Target cell
• End feet of Astrocytes are also found covering most of the synapse
• Gap is known as the Synaptic Cleft
• Synaptic vesicles are found in the Presynaptic membrane and they are full of
Neurotransmitters
• Receptors specific to the Neurotransmitters are found in the Postsynaptic Membrane

Chemical Synapses:
• Action Potential positive enough to open up Na ion voltage-gated channels and allow
Na positively charged ions to enter

Advanced Neurophysiology (1st Year University notes)
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Increase in positive charge opens up Ca ion channels to open and influx of Calcium
ions occur
Snare Proteins - Proteins that connect the presynaptic vesicles to the membrane
Ca ions bond to proteins to stimulate fusion of vesicles to the presynaptic membrane
(Exocytosis)
Neurotransmitters enter Cleft and bond to special receptors (Nicotinic Cholinergic
Receptors for Acetylcholine)
This causes Na gated channels to open up at the Postsynaptic membrane causing
an influx of Na ions into the Target cell
However, instead of Na channels opening, K channels may open up instead at the
Postsynaptic membrane, causing K ions to leave the neuron,
This making it harder for action potential to occur at the Postsynaptic neuron due to a
less positive charge



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