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Nerves
Nerves are thread-like structures that form a network of pathways that transmit information from the brain to the body and the body to the brain, in the form of electrical impulses.
1,605 Questions
A neural signal is received at a neuron when neurotransmitters released by a pre-synaptic neuron diffuse across the synaptic cleft and settle in to receptor sites on ligand-gated sodium ion pores typically located on the dendrites or dendritic spines of the post-synaptic neuron.
As the ligand-gated pores open, sodium ions enter the neuron, and their electric fields repel one another down the dendrite and across the soma (body of the neuron), by a process known as electrotonic conduction. This is considered a graded response, because it can vary from small to large values.
If enough sodium ions pile up at the end of the soma where the axon begins (the axon hillock), by a summation of either multiple or fast inputs, yielding a voltage above the trigger voltage, it will trigger the opening of voltage-gated sodium ion pores in the initial segmentof the axon.
As sodium ions pour into the axon through the v-gated ion pores, they open nearby v-gated sodium ion pores, more sodium ions come in, more v-gated ion pores open, and this process continues down the length of the axon in a process known as the action potential.
When the action potential reaches the ends of the axon, the axon terminals, the voltage causes voltage-gated calcium ion pores to open, allowing calcium ions into the axon terminals, which instigate a biochemical process to occur which causes small sacs (called vesicles) containing messenger chemicals called neurotransmitters to be moved into contact with the cell membrane, where they fuse with the membraneand release their contents into the synaptic cleft.
Why is it that the electrical impulse cannot pass from neuron the muscle cell?
There is a space (synapsis) between the neuron and the muscle cell. The electrical impulse can not pass over that. Chemical neurotransmitters are manufactured by neurons in the soma, then stored in little bundles called synaptic vesicles and transferred to the synapses. The release of the neurotransmitter is required for a nerve to simulate the muscle. This is what crosses the space.
Which 3 parts of a human neuron are common in all animal neurons?
soma (cell body), axon, and axon terminals. I left out dendrites, because there are some kinds of neurons (sensory neurons) which don't have dendrites, but rather have axons which come from a sense receptor cell, come to but do not enter the soma, where the impulse continues onalong a second branch of the axon stub which comes out from the soma. In other words, a single axon (or perhaps a fused axon and dendrite?) comes out from the soma, where it branches into two, one of which goes to the receptor cell to receive an impulse (and is myelinated and conducts an action potential), and the other goes to the spinal cord or brain.
What is hydrogen isotope with two neurons?
The hydrogen isotope with two neutrons is called deuterium. It is a heavier and stable form of hydrogen, commonly used in nuclear reactions and heavy water production.
If the inside of the neuron is negatively charged compared to the outside the neuron is in the?
If it's approximately -70 mV, then it's in a resting state.
How is a reflex nerve impulse different than other nerve impulses?
Skeletal muscles interact with the spinal cord
What type of message allows one neuron to communicate with another neuron?
There are two main ways Neurons communicate to each other:
1) via chemical messengers
2) via electrical potentials
The main form of communication via neurons to neurons in a chemical messenger so I will explain this one.
An example of a chemical messenger is when one neuron releases glutamate from its axon. Glutamate is an neurotransmitter (NT) created in our body, it's purpose is to excite the neuron it is received by.
So for instance ( and this is a very general example this is not how pain works completely I just made up this example to demonstrate how the communication happens. ) lets say you touch a hot stove. An interneuron in your spinal cord receives the pain signals. How can it communicate to the brain neurons you are in pain? Well the interneuron can release the glutamate from it's axon, and then NT glutamate will travel to neuron b who has receptors for glutamate. When the glutamate binds to neurone b's receptors, neuron b will become excited.
What are nerve cells that engulf cellular waste and destroy microorganisms in nerve tissue?
Microglia are nerve cells that act as the primary immune cells in the central nervous system. They engulf and digest cellular waste and foreign microorganisms to maintain brain health and protect nerve tissue from damage.
threshold
The parts of a generic neuron are:-
soma - cell body
axon - upto 1 meter long
dendrite - many
What is the function of the peripheral nervous system?
Numerous functions: it carries all the informations that comes from the skin to the brain (the sensitive system), and also all the movement commands from the brain to the muscles (motor system). All the information are also integrated in diffent parts of the brain, allowing us to do everything.
The sensitive system carries up information about pain, heat, cold, pressures, friction, pleasure, and tact, through nerve endings distributed beneath our entire skin; it also has terminals in the muscles and joints, that inform how cantracted a muscle is or how bent a joint is at any moment, thus the brain knows where in the space each part of our body is.
The motor system comes down from the brain through the inner part of the spinal chord (the sensitive goes up through the same organ, organised in different bundles, the tracts, at the outter part; different sensations travel through different bundles, in different parts, e.g., tact goes by the back part, the dorsal tract, whereas pain goes by the front and sides). The nerve endings are located in the muscles of the body, and when activated causes them to contract, at different intensities, which will depend on how much strength was required.
How does the structure of the nucleus relate to its function?
The nucleus is a membrane-bound organelle that contains genetic material (DNA) of eukaryotic organisms. As such, it serves to maintain the integrity of the cell by facilitating transcription and replication processes. It's the largest organelle inside the cell taking up about a tenth of the entire cell volume.
What relays information between the brain and the eyes and ears?
Neurons and synapses relay information between the brain and eyes and ears. Neurons take in signals from your eyes and ears, and the electrical impulses are transferred to the brain to be processed into thought and sensation. The brain also sends impulses to the eyes and ears to make them function.
Most nerve entrapment syndromes are caused by injury to the nerve as it travels between a canal consisting of bone or ligament.
What reactions leap across synapses?
Reactions don't leap across synapses but neurotransmitters will diffuse across the synaptic cleft.
What are the side effect of nerve block in thigh area of the leg after surgery?
Loss of temporary feeling
How does LSD affect the synapse?
Yes, LSD exerts it's effects by affecting neurons. Primarily, it binds to 5-HT2A receptors, and thus mimics serotonin in some respects (but certainly not all, which accounts for it's low toxicity compared to the active dose). It also binds to other receptors, such as adrenergic and dopamine receptors, but it's psychedelic effects are due to the serotonergic properties.
It is important to note that despite it's effects on neurons, it has not been demonstrated to cause neurotoxicity. Thus, contrary to popular belief, it generally is harmless to neurons in all but the highest doses (many thousands of times as an average dose).
What does the sheath do in a nerve cell?
The myelin insulating sheath speeds up signal propagation down the axon. It also acts like the covering on any electric cord. It only covers the axon and since it is made of fatty materials, it appears white. The cell and dendrites appear gray.
Do fibers of the optic nerve synapse at lateral genticulates of the thalamus?
It is a true statement that fibers of the optic nerve synapse at lateral genticulates of the thalamus.
Potential energy = mass x gravitational acceleration x height
Do the action potential travel along the axon of a neuron?
fig. 1
Formation of an action potential
The formation of an action potential can be divided into five steps. (1) A stimulus from a sensory cell or another neuron causes the target cell to depolarize toward the threshold potential. (2) If the threshold of excitation is reached, all Na+ channels open and the membrane depolarizes. (3) At the peak action potential, K+ channels open and K+ begins to leave the cell. At the same time, Na+ channels close. (4) The membrane becomes hyperpolarized as K+ ions continue to leave the cell. The hyperpolarized membrane is in a refractory period and cannot fire. (5) The K+ channels close and the Na+/K+ transporter restores the resting potential.
