PSY 102 Lecture Notes - Lecture 3: Myelin, Axon Terminal, Neuroglia
14 Jun 2018
School
Department
Course
Professor
Chapter 3 – PSY Notes
Neurons: The Brains Communications
- The nervous system is a complex communication network
- The nervous system handles information, just as the circulatory system handles blood
- Neurons – nerve cell specialized for communication
- The cell body also called the soma is the central region of the neuron
- - it manufactures new cell components, which consist of small and large
molecules
Dendrite – portion of neuron that receives signals
- They listen in on the info that is being passed on and give it to the cell body
Axons – portion of neuron that sends signals
- Very thin and near the cell body
- Axon terminal is like a knoblike structure at the far end of the axon they have synaptic
vesicles
Synaptic vesicles – spherical sac containing neurotransmitters
- They contain neurotransmitters
Neurotransmitters – chemical messenger specialized for communication from neuron to
neuron
Synapse – space between two connecting neurons through which messages are transmitted
chemically
- The space neurotransmitters go through
Synaptic cleft – a gap into which neurotransmitters are released from the axon terminal
- This gap is covered by small patches of membrane on each side
Glial cell – cells in nervous system that plays a role in the formation of myelin and the blood-
brain barrier, responds to injury, removes debris, and enhances learning and memory
- Hold neurons in place
- These cells create insulating wrapper around axons called myelin sheath
- Myelin Sheath – glial cells wrapped around axons that act as insulators of the neurons
signal
- - these sheaths have many gaps along the axon called nodes , which help the
neuron conduct electricity more efficiently
find more resources at oneclass.com
find more resources at oneclass.com
Electrifying Thought
- Neurons respond to neurotransmitters by generating electrical activity
- The electrodes that carry the energy allow them to measure potential difference in
electrical charge inside versus outside the neuron
- When there are no neurotransmitters acting on the neurons the membrane is at resting
potential
- - Resting potential – electrical charge difference (-60 millivolts) across the
neuronal membrane, when the neuron is not being stimulated or inhibited
- When the electrical charge inside the neuron reaches a high enough level relative to the
outside, it’s alled threshold, and an action potential occurs
- Threshold – membrane potential necessary to trigger an action potential
- Action potential – electrical impulse that travels down the axon triggering the release of
neurotransmitters
- - triggered by change inside the axon
- Absolute refractory period – time during which another action potential is impossible,
limits maximal firing rate
- Receptor site – location the uniquely recognizes a neurotransmitter
- - Different receptor sites recognize different types of neurotransmitters
- Reuptake – means of recycling neurotransmitters
- - neurotransmitters can be halted by reuptake of the neurotransmitter back into
the axon terminal – a process by which the synaptic vesicle reabsorbs the
neurotransmitter
Neural Plasticity
Plasticity – the nervous systems ability to change
The network of neurons in the brain change over the course of development if four ways:
1. Growth of dendrites
2. Synaptogenesis, the formation of new synapses
3. Pruning, consisting of the death of certain neurons and the retraction of axons to
remove connectios that are’t useful
4. Myelination, the insulation of axons with a myelin sheath
Stem cells – a cell often originating in embryos having
Neurogenesis – creation of new neurons in the adult brain
find more resources at oneclass.com
find more resources at oneclass.com
The Brain – Behaviour Network
- Sensory information comes into – and decisions to act come out of – the central
nervous system (CNS)
- Central nervous system (CNS) – Part of nervous system containing brain and spiral cord
that controls the mind and behaviour
- The nerves that extend outside the of the CNS Peripheral Nervous System (PNS)
- Peripheral Nervous System (PNS) – Nerves in the body that extend outside the central
nervous system (CNS)
- - PNS is further broken down into the somatic nervous system – controls
voluntary behaviour. Connected to the muscles and sensory receptors
- - Efferent nerves: outgoing; carry motor commands from the central
nervous system to the muscles
- - Afferent nerves: incoming; carry information from sensory receptors in
the skin, muscles, and joints to the central nervous system
- - And the autonomic nervous system – controls involuntary (automatic
functions)
- - connects to the heart, blood vessels
- Sympathetic division – mobilizes the body for emergencies
- Parasympathetic – oserves the ody’s resoures
Central Nervous System: The Command Center
CNS – Brain and spinal cord
- The brain is protected by the cerebral ventricles, fluid filled pockets that extend
throughout the entire brain and spinal cord.
- Cerebrospinal fluid (CSF) runs through the ventricles and bathes our brain and spinal
cord providing nutrients and cushioning us against injury
The Cerebrum or (Forebrain)
- Is the most developed area of the brain
- It consists of two cerebral hemispheres
Cerebral Hemispheres – two halves of the cerebra; cortex, each of which serve distinct yet
highly integrated functions
- The Corpus callosum connects the two hemispheres
Corpus Callosum – large band of fibres connecting the two cerebral hemispheres
Cerebral cortex – outermost part of forebrain, responsible for analyzing sensory processing and
higher brain functions
- Largest component of the cerebrum
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
The nervous system is a complex communication network. The nervous system handles information, just as the circulatory system handles blood. Neurons nerve cell specialized for communication. The cell body also called the soma is the central region of the neuron. It manufactures new cell components, which consist of small and large molecules. Dendrite portion of neuron that receives signals. They listen in on the info that is being passed on and give it to the cell body. Axons portion of neuron that sends signals. Very thin and near the cell body. Axon terminal is like a knoblike structure at the far end of the axon they have synaptic vesicles. Neurotransmitters chemical messenger specialized for communication from neuron to neuron. Synapse space between two connecting neurons through which messages are transmitted chemically. Synaptic cleft a gap into which neurotransmitters are released from the axon terminal. This gap is covered by small patches of membrane on each side.
