chemical synapses include neutotransmitter. It is a chemical synthesized and released from presynaptic nerves. There is a small gap between presynaptic and postsynaptic membrane that is called as synaptic cleft. This cleft is filled with mucopolysaccarides that attaches to the pre-and posysynaptic membranes. The neurotransmitters are stored in the vesicle in thepresynaptic axon end. The axon terminal contains many mitochondria and synaptic vesicles.
The sequence of events during chemical synaptic transmission is :
1- the presynaptic action potential depolarizes the presynaptic membrane. 2- Ca+ permeability increase through the presynaptic membrane.
3-the elevated intracellular Ca+ concentration causes the release of neurotransmitter from synaptic vesicles in to synaptic cleft.
4- Neurotransmitter molecules diffuse across the synaptic cleft to the postsynaptic membrane and they reversibly bind to the specific receptors on the postsynaptic membrane.
Ca is very important in neurotransmitter release . The neuromucular junction is a typical chemical synapse. In this case two acetylcoline molecule are required to open the sodium channel. Postsynaptic membrane include acetycholine esterase to remove ACh.
In each postsynaptic end, a small depolarization is generated. That is called as end plate potential (EPP) or postsynaptic endplate potential.
These mini EPPs reflect the spontaneous release of one, or a few synaptic vesicles. Single EPPs does not generate in chemical synapsis . This ranges from 0.5 msec to 2.0 msec or even more.
chemical synapses
electrical synapses
Electronic conduction is provided by gap junction between two neuronal membrane. these gap junctions are composed of numerous connections that allow direct movement of ions and small molecules. The direct electrical coupling of neurons is often observed when there is a requirement for the closesyncronization of effector organs. Examples are the cells of lobster heart, the electronic organ of mormyrid fish. the sound production muscle of toadfish and the escape response of some invertebrates.
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There is no time delay, or latency in transmission of electrical depolarization in electrical synapses. The normal direction of synaptic transmission is from the presynaptic membrane to the postsynaptic membrane. Some electrical synapsis are inhibitory.
Synaptic Transmission
Action potentials are transmitted from one cell to another. There are two different mechanism for transfer of electrical from one cell to another .
1) electrical synapsis
2)chemical synapses
in electrical synapses, the action potential jumps electrotonically from the presynaptic cell membrane to the postsynaptic cell membrane. In the chemical synapsis, neurotransmitter released from one cell provide transmission of impulses.
What Happens To The Nervous System Under Stress?
The nervous system is the messenger between the brain and the other parts of the body. It is a labyrinth of connections that ensure that every signal transmitted by the brain triggers the necessary response in the body. Needless to say, it is an indispensable part of the body mechanism yet one of the most neglected ones. The nervous system remains active even when the rest of the body is in the resting state. It is also the main center for triggering the fight or flight response and the involuntary responses that keep us safe from potentially harmful stimuli.
When the nervous system is neglected i.e. by lack of proper sleep, stress and other factors, the repercussions are slowly but surely felt. The severity might vary from mood swings, poor hand eye co-ordination, fatigue to even depression and Alzheimer’s disease. The nervous system can also be affected adversely by improper food and sleeping patterns, lack of exercise, excessive exposure to stimulants such as coffee, certain medication and neglecting the need for relaxing activity. When the nervous system is not in ship shape, it can lead to the impairment of daily life and significantly increase the risk of occurrence of other medical conditions.
On the other hand, when the nervous system is performing to its full potential it fortifies the immune system, the ability to focus and multitask increases, the capacity to perform complicated tasks is enhanced and the risk of depression is significantly lowered. It also contributes towards a positive frame of mind and improving resistance towards stress. As the nervous system affects the body, the vice versa also holds true. Proper nutrition, rest and regular exercise release beneficial hormones such as endorphins into the system and help balance the several regulatory mechanisms of the body. A healthy body is truly run by a healthy nervous system.
Nervous System general
do you want to explore the nervous system ? this is general nervous system video.. there is a biochemical communications network of the human body, Revealing visuals are supported by informative features in which a neurologist discusses the chemistry of a nerve impulse.
