body's trip

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...

•At the point of contact with the hot cookie , skin receptors quickly sent nerve impulses (electrical) to the spinal cord (central nervous system) via sensory neurons .

•In the spinal cord the nerve impulses move from sensory neurons to the interneurons (also known as relay neurons) by the chemical and electrical massages .which i will discovered and explain for you how dose that work in a few seconds . . . just keep following .

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.

Chemical transmission

  1. The action potential signal arrives at the axon terminal (the bouton).
  2. The local depolarization causes Ca2+ channels to open.
  3. Ca2+ enters the presynaptic cell because its concentration is greater outside the cell than inside.
  4. The Ca2+, by binding with calmodulin, causes vesicles filled with neurotransmitter to migrate towards the presynaptic membrane.
  5. The vesicle merges with the presynaptic membrane.
  6. 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.
  7. The neurotransmitter diffuses through the synaptic cleft and binds with receptor channel membranes that are located in both presynaptic and postsynaptic membranes.
  8. The time period from neurotransmitter release to receptor channel binding is less than a millionth of a second.

Postsynaptic Stimulation

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-

The impulses are then sent to motor neurons which project out of the spinal cord.. which will stimulate Sultan’s muscles (effector) to contract hence snatching his hand away from the hot cookie . This is known as a ‘reflex arc’. This process happens so fast that the response occurs before the message reaches the brain or the message may not be sent to the brain at all.

eating the sweet coooookie - endocrine system.

When he will eat the cookie the glucose in the blood will increase and the hypothalamus will receive action potential and release thyrotrophic-releasing hormone (TRH) hormone to the pituitary to give the (hormone name ) to the pancreas .

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.

the end

and that is the end of our trip today . .

done by FatimaSultan , Khoulud Haji .