nerves system - endocrine system .
So lets start our trip into Sultan’s body after he touched the hot cookies that I baked freshly to see how it will effect his nervous system and endocrine...
How do the chemical and electrical massage transmit ??
•At the end of each nerve cell there is a synaptic terminal .This is full of extremely tiny sacs which hold neurotransmitter chemicals .
• These chemicals transmit nerve impulses from one nerve to another or from nerves to muscle cells.
• An electrical nerve impulse travels along the neuron to these sacs which then release the neurotransmitter chemicals.
• The chemicals move along to the next neuron sparking an electrical charge which moves the nerve impulse forward.
- The action potential signal arrives at the axon terminal (the bouton).
- The local depolarization causes Ca2+ channels to open.
- Ca2+ enters the presynaptic cell because its concentration is greater outside the cell than inside.
- The Ca2+, by binding with calmodulin, causes vesicles filled with neurotransmitter to migrate towards the presynaptic membrane.
- The vesicle merges with the presynaptic membrane.
- The presynaptic membrane and vesicle now forms a continuous membrane, so that the neurotransmitter is released into the synaptic cleft. This process is called exocytosis.
- The neurotransmitter diffuses through the synaptic cleft and binds with receptor channel membranes that are located in both presynaptic and postsynaptic membranes.
- The time period from neurotransmitter release to receptor channel binding is less than a millionth of a second.
Once the postsynaptic ion channel is opened, whether directly or indirectly, the effect can be either excitatory (depolarizing) or inhibitory (hyperpolarizing).
- Excitatory Postsynaptic Potentials (EPSP)
- Excitatory ion channels are permeable to Na+ and K+
- Because of the electrical and concentration gradient, more Na+ moves into the cell than K+
- The inside of the cell becomes more positive, hence causing a local depolarization
- If enough depolarization occurs (for example, because the neurotransmitter released caused nearby ion channels to open), an action potential is generated
- Inhibitory Postsynaptic Potentials (IPSP)
- Inhibitory ion channels are permeable to Cl- and K+
- Because of the concentration gradient (not electrical), Cl- moves into the cell and K+ moves out of the cell
- The inside of the cell thus becomes more negative, hence causing a local hyperpolarization
- The hyperpolarization will make it more difficult for the cell membrane potential to reach threshold, thereby making it less likely that an action potential will be generated
Reaction -reflex arc-
cells in his pancres (known as beta cells) will be signaled to release insulin into your bloodstream. Insulin then attaches to and signals cells to absorb sugar from the bloodstream. Insulin is often described as a “key,” which unlocks the cell to allow sugar to enter the cell and be used for energy.
why dose that happens ?
•If you have more sugar in your body than it needs, insulin helps store the sugar in your liver and releases it when your blood sugar level is low or if you need more sugar, such as in between meals or during physical activity. Therefore, insulin helps balance out blood sugar levels and keeps them in a normal range. As blood sugar levels rise, the pancreas secretes more insulin.
done by FatimaSultan , Khoulud Haji .