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May 26, 2021 · Neuromodulators trigger second messenger cascades that affect neural circuits in two broad ways: (1) changing the excitability or temporal pattern of neuron activity and (2) altering the strength of synaptic connections between neurons (Marder and Bucher 2001; Dickinson 2006).
- Charlotte L Barkan, Elizabeth C Leininger, Erik Zornik
- 2021
- Information exchange in the nervous system
- Synaptic transmission
- HOW THE NERVOUS SYSTEM IS ORGANISED
- THE NEURON
- Dendrites
- Inside the neuron
- Neuron classification
- Types of glial cell
- Radial glial cells (CNS)
- Glial cells and injury
- INFORMATION EXCHANGE IN THE NERVOUS SYSTEM
- THE RESTING MEMBRANE POTENTIAL
- SUMMATION EFFECTS
- THE SYNAPTIC VESICLE
- MODULATION OF SYNAPTIC TRANSMISSION
- NON-SYNAPTIC CHEMICAL COMMUNICATION
- NEUROTRANSMITTERS
- Glutamate (glutamic acid)
- Melatonin
- SOLUBLE GASES
- SUMMARY
- KEY QUESTIONS
The resting membrane potential The action potential and nerve impulse Summation effects
The synaptic vesicle Modulation of synaptic transmission Non-synaptic chemical communication Postsynaptic receptors and receptor types
In vertebrates, the nervous system has two divisions: the peripheral nervous system and the central nervous system (Figure 1.1). The central nervous system (CNS), which consists of the brain and spinal cord, is surrounded by another nervous system called the periph-eral nervous system (PNS). The PNS gathers information from our surroundings and env...
Neurons are the basic information processing structures in the CNS. They are electrically excitable cells that process and transmit information around the nervous system. Neurons transmit information either by electrical or by chemical signalling, which as you will see later occurs via synapses. Neurons are the core apparatus of the nervous system,...
Take information away from the cell body Large axons have a distinct swelling called Bring information to the cell body No hillock the axon hillock Usually have few or no ribosomes Smooth surface Often covered with myelin Generally only one axon or none per cell Cell Body Usually have ribosomes May have rough surface: spiny as in pyramidal cells or...
The inside of a neuron is much like the other cells of the body in many ways, as a neuron has many of the same organelles, including a nucleus and mitochondria. Figure 1.3 shows the following components of a typical animal cell: Nucleus: contains genetic material within the chromosomes comprising information for development and maintenance of the c...
The study of the microscopic anatomy of cells and tissues is termed histology (see Box 1.1). As with many things in the nervous system, neurons may be classified in a variety of ways, according to their function (sensor, motor, interneuron), their location (cortical, subcorti-cal), the identity of the neurotransmitter they synthesise and release (c...
A number of different types of glial cell exist. Some can be found in the central nervous system and others are essential to the functioning of the peripheral nervous system.
Radial glial cells (RGCs) are a temporary cell population present only in the developing central nervous system. They function both as precursor cells and as a scaffolding frame-work to support neuron migration.
As already suggested, the glial cells react to both central and peripheral nervous system damage, supporting neurons. The debris from injuries in the CNS, like a stroke, is engulfed by astrocytes and digested in the process of phagocytosis. Scar tissue is also formed as astrocytes fill the gaps that occur because of tissue death. Oligodendrocytes i...
Neurons constantly relay information between each other, and also between themselves and their environment. Information is transmitted from cell to cell using the following forms: axon to dendrite – axodendritic exchange axon to cell body – axosomatic exchange axon to axon – axoaxonic exchange dendrite to dendrite – dendrodendritic exchange. The ce...
The resting potential (or resting voltage) of the cell is the membrane potential that is main-tained if there are no action potentials or synaptic potentials present. The intracellular fluid of a neuron at rest is more negatively charged than the extracellular fluid, and this polarity difference is termed the resting potential. The resting membrane...
Neurons receive multiple excitatory and inhibitory inputs on a continual basis. The determination of whether the axon will fire or not is based on the total effect of all excitations and inhibitions that take place. So, at what point is an action potential produced? The EPSPs and IPSPs received by the dendrites and cell bodies of the neu-rons are g...
When an action potential arrives at the presynaptic terminal, calcium channels open and Ca+ ions enter the cell. This calcium influx causes the movement and fusion of secretory vesicles to the cell membrane (a process known as exocytosis). Within the presynaptic cell, vesicles holding neurotransmitters are placed or ‘locked in’ at the synaptic memb...
Various processes affect the amount of the neurotransmitter required for release. One process called presynaptic inhibition causes a decrease in the quantity of neurotransmit-ter released despite an action potential in the presynaptic neuron. This takes place when a neurotransmitter release from one neuron impacts on the release of another neuron t...
While neurotransmitters are released from the terminal buttons and have a local effect, neuromodulators – another communication substance released by neurons – travel greater distances and are dispersed more widely around the nervous system. Most neuromodulators are peptides, which are chains of amino acids linked together by peptide bonds. Neuromo...
We can categorise neurotransmitters into two broad groupings: the ‘classical’ small mol-ecule neurotransmitters, and the larger neuropeptide neurotransmitters (Figure 1.7). Among neurotransmitters in the category of small molecule neurotransmitters there is a group termed the monoamines; these include dopamine, noradrenaline and serotonin, which ar...
Glutamate is the most commonly found excitatory neurotransmitter. The excitatory action of glutamate is stopped by a chloride-independent membrane transport system that reab-sorbs glutamate and aspartate into the presynaptic membrane. The N-methyl-D-aspartate (NMDA) glutamate receptor is one of the subtypes of the glutamate receptors and is the onl...
Melatonin is derived from serotonin within the pineal gland and the retina. The pineal paren-chymal cells secrete melatonin into the blood and cerebrospinal fluid. Melatonin plays a role in the sleep/wake cycle; its synthesis and secretion rise during the dark hours and are maintained at a low level during daylight hours (see Chapter 9). Melatonin ...
Certain soluble gases also act as neurotransmitters. Nitric oxide (NO) is produced by many cells in the body such as the vascular endothelium cells; it is central in the regulation of blood flow and may also play a role in memory and learning. Another soluble gas, carbon monoxide, does not appear to be released in a directed manner but may play a r...
In this chapter we have discovered that the nervous system has two divisions: the periph-eral nervous system (PNS) and the central nervous system (CNS). We have also discussed the various cells of the nervous system and seen that the cell body of the neuron contains all the components that allow the cell to function. Neurons may be classified in a ...
Describe the organisational structure of the nervous system. How is information transmitted around the nervous system? What are the different types of neurotransmitter?
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What is neuromodulator? Neurotransmitters. 90% 9% Amino acids (Glutamate, GABA, Glycine, etc) Gas (NO, CO, H2S)
May 25, 2021 · The human nervous system consists of the: Central nervous system (CNS) – the brain and the spinal cord; Peripheral nervous system (PNS) – all of the nerves in the body; It allows us to make sense of our surroundings and respond to them and to coordinate and regulate body functions
OCR (A) Biology A-level. Topic 5.1: Communication and homeostasis. Notes. Communication is essential for the survival of organism as all living organisms must be able to detect and respond to changes in their internal and external environments.
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Systems biology can be described as “Integrative Biology” with the ultimate goal of being able to predict de novo biological outcomes given the list of components involved (Edison T. Liu, Cell, Vol 121, 505‐506, 2005. Genome Institute of Singapore).
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Aug 1, 2000 · A complete answer to this question requires identification of the neural circuits responsible, the different neural components involved, their connectivity, transmitters, the types of channels they possess, and their modulation via various receptors.
