Visceral Reflex Arcs - Video Tutorials & Practice Problems
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concept
Visceral Reflex Arcs
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2m
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Video transcript
this video, we're gonna be talking about visceral reflex arcs. Now, these are going to be very similar to somatic reflex arcs, which we covered in our chapter on the peripheral nervous system, but there are 3 main differences. So, first, these visceral reflex arcs are going to have 2 consecutive neurons in their motor component. We've talked about this a whole bunch already so we're going to have our preganglionic fiber and our postganglionic fiber. Next, the afferent fibers are going to be visceral sensory neurons rather than somatic sensory neurons. And finally, the effectors here are going to be smooth muscle, cardiac muscle, and glands rather than primarily skeletal muscle like we saw in those somatic reflex arcs. Now these visceral reflex arcs have 5 steps and the 5 steps exactly mirror what we already saw in those somatic reflex arcs. So first, we're going to have a receptor so we're going to have a sensory receptor located somewhere in our viscera, and then we'll have our visceral sensory neuron. You can see that here in blue and that will transmit an impulse from the receptor to our central nervous system. And then we will enter our integration center and this will consist of either an interneuron or a single synapse between our sensory and our motor neuron. And for these visceral reflex arcs, that integration center can either be in the spinal cord in the brain or in the gastrointestinal tract. And then we will have our motor neuron and like I said here we're going to have now a 2 neuron chain. So, we're going to have our preganglionic neuron and then our postganglionic fiber there. And then, finally, that message will get sent out to our visceral effector which is going to be either, like I said, smooth muscle, cardiac muscle, or a gland that will respond to that stimulus. So all in all, very similar, like I said, to those somatic reflex arcs but just a couple of key differences there. Alright, and I will see you guys in our next one. Bye bye.
2
example
Visceral Reflex Arcs Example 1
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1m
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Video transcript
Okay. So this one asks us the integration step of a visceral reflex arc might include which of the following and we're gonna be circling all that can apply. So remember, this integration step is when our sensory neuron and our motor neuron are basically communicating and it can involve a single synapse or it can involve an interneuron. And typically, this will be happening in the spinal cord but it can also happen in the walls of the gastrointestinal tract. So, looking at our answers here, it looks like a fits the bill. That's a direct synapse with a preganglionic neurons. We have our direct synapse. B is cardiac muscle and this is not going to be happening in cardiac muscle. So b would definitely be out. C, walls of the gastrointestinal tract, that is a location where we can have integration in our autonomic nervous system. And then d is an interneuron in the dorsal horn. Again, remember this can involve a single synapse or an interneuron right there in that spinal cord. So d would also apply. So our answers here are going to be a, c, and d. And there you go.
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Problem
Problem
Visceral effectors include:
A
Smooth muscle, skeletal muscle, glands.
B
Smooth muscle and glands.
C
Skeletal muscle, smooth muscle, cardiac muscle.
D
Smooth muscle, cardiac muscle, glands.
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