Biopsychology
PSY320
Notes of Nadine Alhamzawi
─
Neurons
Learning how the brain functions helps us understand the biological basis behind human
psychology.
The nervous system comprises two basic cell types; goal cells and neurons.
Glial cells: 10 times more than neurons, support neurons physically and
metabolically. Glial cells help neurons line up, communicate, provide insulation, and
transport nutrients and waste products.
Neurons: interconnected information processors that are essential for all tasks of
the nervous system. The central building blocks of the nervous system.
Neurons are the central building blocks of the central system, 100 billion strong at birth,
and consist of different parts specialised in different functions. It has a semipermeable
membrane that allows smaller and non-electrical molecules to pass through it.
Axon: a major extension signals travel across. Range between an inch to several feet.
Soma: the cell body, contains the nucleus.
Dendrites: branching extensions, input sites,
receive signals, transformed electrically.
Terminal Buttons: signals end here, and
contain synaptic vesicles.
Synaptic Vesicles: house neurotransmitters.
Neurotransmitters: the chemical messengers.
Myelin Sheath: an insulator that increases the
speed at which the signals travel.
Synapse: a very small space between two neurons, the site where communication between
neurons occurs.
Multiple Sclerosis (MS): characterized by an autoimmune response, results in extensive
damage to the myelin sheath covering axons across the nervous system.
, 2
Neurotransmitter Receptors: proteins on cell surfaces, vary in shape, forming a
lock-and-key relationship with neurotransmitters.
Transmitter
Function:
Neurons are surrounded by a membrane that separates extracellular and intracellular
fluids. This membrane maintains a difference in electrical charge called the membrane
potential, which powers signal transmission.
During resting periods, the neuron is in a state of readiness known as the resting potential.
Ions line up on either side of the membrane,
ready to move when the neuron becomes active
and its gates open. Sodium and potassium ions,
in particular, move across the membrane
through a sodium-potassium pump. Sodium
ions (Na+) are more concentrated outside the
cell and tend to move in, while potassium ions
(K+) are more concentrated inside and tend to
move out. Additionally, the interior of the cell is
slightly negatively charged compared to the
exterior, further driving sodium ions inward.
When a neuron at rest receives a signal, gates on its membrane open, allowing Na+ ions to
enter, making the cell more positive. If this charge surpasses a threshold, called the
excitation threshold, the neuron becomes active, starting the action potential. This phase,
called depolarization, sees a surge of Na+ ions entering, causing a peak in the membrane
potential. Then, potassium ions exit, leading to repolarization, where the cell becomes
slightly more negative before returning to its resting state.
This positive spike, the action potential, is an electrical signal moving from the cell body
along the axon to the terminals. Sodium ions entering the cell at each point raise the
charge, triggering more sodium influx. It's an
all-or-none event, explaining why distant injuries
feel similar. Neurotransmitters released at
terminals regulate neuronal signalling. Excess
neurotransmitters are cleared via reuptake,
controlling signalling between neurons. Neuronal
communication blends electrical and chemical
events: action potentials are electrical, and
neurotransmitter movement is chemical.
, 3
Psychoactive drugs:
Neurotransmitters play key roles in brain function. Psychological disorders like depression
and schizophrenia often involve imbalances in these chemicals. Psychotropic medications
help alleviate symptoms by targeting neurotransmitter systems. Drugs can act as agonists,
mimicking neurotransmitters, or antagonists, blocking their effects. For instance, dopamine
agonists treat Parkinson's by mimicking dopamine effects. Reuptake inhibitors, like SSRIs
for depression, prevent neurotransmitter reabsorption, prolonging their effects.
Understanding these mechanisms is crucial for treating neurological conditions effectively.
The Nervous System
The Central Nervous System (CNS):
It consists of the brain and the spinal cord
The Peripheral Nervous System (PNS):
Comprises nerves connecting the central nervous system
(CNS) to the body's muscles, organs, and senses. It is divided into the somatic and
autonomic systems.
The Somatic System: controls voluntary actions via motor and sensory neurons.
The Autonomic System: regulates internal organs involuntarily, with sympathetic
activation preparing the body for stress and parasympathetic activation restoring calm.
This dynamic interplay maintains homeostasis.
In stress, the sympathetic system triggers physiological
changes for fight or flight, while the parasympathetic
system restores normalcy once the threat subsides.
PSY320
Notes of Nadine Alhamzawi
─
Neurons
Learning how the brain functions helps us understand the biological basis behind human
psychology.
The nervous system comprises two basic cell types; goal cells and neurons.
Glial cells: 10 times more than neurons, support neurons physically and
metabolically. Glial cells help neurons line up, communicate, provide insulation, and
transport nutrients and waste products.
Neurons: interconnected information processors that are essential for all tasks of
the nervous system. The central building blocks of the nervous system.
Neurons are the central building blocks of the central system, 100 billion strong at birth,
and consist of different parts specialised in different functions. It has a semipermeable
membrane that allows smaller and non-electrical molecules to pass through it.
Axon: a major extension signals travel across. Range between an inch to several feet.
Soma: the cell body, contains the nucleus.
Dendrites: branching extensions, input sites,
receive signals, transformed electrically.
Terminal Buttons: signals end here, and
contain synaptic vesicles.
Synaptic Vesicles: house neurotransmitters.
Neurotransmitters: the chemical messengers.
Myelin Sheath: an insulator that increases the
speed at which the signals travel.
Synapse: a very small space between two neurons, the site where communication between
neurons occurs.
Multiple Sclerosis (MS): characterized by an autoimmune response, results in extensive
damage to the myelin sheath covering axons across the nervous system.
, 2
Neurotransmitter Receptors: proteins on cell surfaces, vary in shape, forming a
lock-and-key relationship with neurotransmitters.
Transmitter
Function:
Neurons are surrounded by a membrane that separates extracellular and intracellular
fluids. This membrane maintains a difference in electrical charge called the membrane
potential, which powers signal transmission.
During resting periods, the neuron is in a state of readiness known as the resting potential.
Ions line up on either side of the membrane,
ready to move when the neuron becomes active
and its gates open. Sodium and potassium ions,
in particular, move across the membrane
through a sodium-potassium pump. Sodium
ions (Na+) are more concentrated outside the
cell and tend to move in, while potassium ions
(K+) are more concentrated inside and tend to
move out. Additionally, the interior of the cell is
slightly negatively charged compared to the
exterior, further driving sodium ions inward.
When a neuron at rest receives a signal, gates on its membrane open, allowing Na+ ions to
enter, making the cell more positive. If this charge surpasses a threshold, called the
excitation threshold, the neuron becomes active, starting the action potential. This phase,
called depolarization, sees a surge of Na+ ions entering, causing a peak in the membrane
potential. Then, potassium ions exit, leading to repolarization, where the cell becomes
slightly more negative before returning to its resting state.
This positive spike, the action potential, is an electrical signal moving from the cell body
along the axon to the terminals. Sodium ions entering the cell at each point raise the
charge, triggering more sodium influx. It's an
all-or-none event, explaining why distant injuries
feel similar. Neurotransmitters released at
terminals regulate neuronal signalling. Excess
neurotransmitters are cleared via reuptake,
controlling signalling between neurons. Neuronal
communication blends electrical and chemical
events: action potentials are electrical, and
neurotransmitter movement is chemical.
, 3
Psychoactive drugs:
Neurotransmitters play key roles in brain function. Psychological disorders like depression
and schizophrenia often involve imbalances in these chemicals. Psychotropic medications
help alleviate symptoms by targeting neurotransmitter systems. Drugs can act as agonists,
mimicking neurotransmitters, or antagonists, blocking their effects. For instance, dopamine
agonists treat Parkinson's by mimicking dopamine effects. Reuptake inhibitors, like SSRIs
for depression, prevent neurotransmitter reabsorption, prolonging their effects.
Understanding these mechanisms is crucial for treating neurological conditions effectively.
The Nervous System
The Central Nervous System (CNS):
It consists of the brain and the spinal cord
The Peripheral Nervous System (PNS):
Comprises nerves connecting the central nervous system
(CNS) to the body's muscles, organs, and senses. It is divided into the somatic and
autonomic systems.
The Somatic System: controls voluntary actions via motor and sensory neurons.
The Autonomic System: regulates internal organs involuntarily, with sympathetic
activation preparing the body for stress and parasympathetic activation restoring calm.
This dynamic interplay maintains homeostasis.
In stress, the sympathetic system triggers physiological
changes for fight or flight, while the parasympathetic
system restores normalcy once the threat subsides.
