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Human Anatomy and Physiology: Case Study
Please help with all or most, really lost and do not understand.
Before drilling on a patient’s tooth, a dentist typically gives the patient a shot of local anesthetic, such as procaine hydrochloride ( Novacain) or lidocaine (Xylocaine). The injection is given in the mouth near the location of nerves that innervate the particular tooth. When the anesthetic reaches the neurons, certain regions of the face, mouth and tongue lack sensation or become numb.
The drug works by blocking neurons communicating with the CNS. The brain is unaware of the presence of painful stimuli in the mouth.
3. The case study states the injection will affect a nerve. What is a nerve? Explain how an impulse travels along a nerve. (Name the parts of a neuron, the processes on the neuron and the membrane channels on each segment of the neuron. 4 points)
Explanation / Answer
Nerves are a collection of neurons.
They are primary cells in nervous system.
They are a bundle of fibers which uses electric and chemical signalsto transmit sensory and motor information from different parts of body.
nerve cells that carry the message are called neurons.
How does the impulse travel?
The place wher the axon of one neuron connet with dendrite of other neuron is called synapse.
The axon of on neuron does not touch the other neurons dendrite there is a gap called synaptic cleft.
The dendrires of one neuron with pick electric nerve impulse and then conduct it through soma or cell body which then travels to axon and from axon of one neuron it travels through synapse to other neuron.
neurons can actulay receive input of other neurons by neurotransmitter and also an action potential is required.
Parts of neuron.
The cell body-contains nucleus nad other organells.dendrites and axon connect to cell body.
Dendrites-part of neuron which receives nerve impulse.
Axon-The part which channels the impulse.
Axon is covered with myelin sheath.A fatty layer that insulates the axon.
Node of Ranveir-A gap between the myelin sheath helping in easy transport of signal.
Mebrane channels on neuron
4 important classes of proteins in the membrane of neurons: Passive/Leakage ion channels, Sodium-Potassium pumps, Voltage-gated ion channels, and Ligand-gated ion channels.
passive leakge ion channel-These are the routes for ions to move across the membrane. They are always open and are distributed throughout the whole neuron. The channel is made up of 5 alpha helices. There are nonpolar parts (exterior) and the and polar parts (interior), causing a polar route through the nonpolar lipid bilayer that is water-filled.
Ligand-gated channels: A ligand is a typically small molecule that is bound by a larger molecule – in this case, the channel protein. A ligand-gated channel is one that opens when it binds a specific ligand. Neurotransmitters are the class of ligands that we will be dealing with. These channels define, and are distributed in, the input region of the neuron (dendrites and soma). These various proteins are targeted as they are synthesized for the various regions of the neurons.
These proteins are in the membranes of neurons, but they aren’t evenly distributed. Lets look at the regions of the neurons and talk about the types of proteins that we find in those regions.
The dendrites and soma: This is where the neuron receives its input and is the integration area of theneuron. Proteins: Ligand-gated ion channels, passive ion channels, Na-K pump.
The Axon hillock and Axon: These allow the neuron to produce and conduct nerve impulses. Proteins: V-gated ion channels, passive ion channels and Na-K pump.
The Axon Terminals: These are the sites of neurotransmitter (NT) release. Proteins: V-gated channels (Ca2+), passive ion channels and Na-K pump.
Sodium-potassium pump (Na-K pump): This pump pumps 3 Na+ ions out for every 2 K+ ions that it lets in.
V-gated ion channels: These channels can be open or closed. The factor that determines whether it is open or closed is the membrane voltage. If it is more positive internally, this can cause the channels to open. There are 2 classes that we will be talking about mainly: Na+ and K+ channels. These occur in the axon and define the axon. Because of these channels, the axon can create and transmit nerve impulses.
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