Effectors of the Autonomic Nervous System (ANS)

by Thad Wilson, PhD

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    00:01 Autonomic Nervous System Effectors.

    00:05 Now, we get to talk a lot about all this different things that happen throughout the body that will able to be doing something.

    00:13 We are not just going to look at things, we are going to look at action today.

    00:20 The Autonomic Nervous System is a large cohort that’s controlling a number of aspects of the body.

    00:28 What we have here are two different columns.

    00:31 These are spinal cord columns.

    00:34 The first one is the autonomic nervous systems, sympathetic component.

    00:39 And then, on the other side, we have the parasympathetic component.

    00:44 The sympathetic component you know because it has paravertebral chain ganglia on both sides of the spinal cord.

    00:53 This will act as relay spots and sometimes where the soma or cell body of the nerve will be.

    01:02 The parasympathetic nervous system, remember, primarily comes from cranial nerve number 10.

    01:09 So this vagus nerve will innervate many of the different organs of the body.

    01:14 These are the same organs that would innervated by those particular sympathetic fibers that come off of the spinal cord.

    01:22 In the parasympathetic nervous system then you also have the splanchnic nerve and some that come from the sacral area.

    01:29 And they will innervate things like the bottom portion of the GI track, places like the bladder and the reproductive organs.

    01:38 So we go through this process, I think it’s best to do this one organ at a time.

    01:44 And so, we do one organ, the next organ, and keep going through those.

    01:48 We’ll talk about what’s the function that’s involve, as well as what receptors will mediate that particular function.

    01:56 Let’s start off with the heart.

    02:00 The heart is going to be innovated by both the sympathetic and parasympathetic nervous system.

    02:07 The SA node, and this is again the area that’s going to control heart rate.

    02:13 If it’s engage by the sympathetic nervous system it’s through Beta-1 (β1) adrenergic receptors, and this will increase heart rate.

    02:24 In contrast, the parasympathetic nervous system, is mediated through muscarinic receptors and that decreases heart rate.

    02:35 The conduction system of the heart especially around the AV node, velocity can change in response to sympathetic comparison sympathetic stimulation.

    02:47 Beta-adrenergic receptors here also increase conduction velocity in the sympathetic nervous system.

    02:54 While muscarinic receptors, this decrease the conduction velocity.

    03:00 In terms of contractility, which is the contraction, the strength of the heart, this is gonna be mediated also by beta-adrenergic receptors.

    03:11 But now, this increases contractility or an atrophy.

    03:16 Muscarinic reflects don’t really have anything to do with the ventricles, to push blood around to the body or to the lungs.

    03:25 What happens to the blood flow that goes to the skin in the muscle? Here we need to talk through which things cause constrictions and dilations.

    03:37 So in the skin, we mainly have alpha-adrenergic receptors that cause vasoconstriction.

    03:44 So vasoconstriction is going to be decreasing the luminal diameter of a blood vessel that reduces the amount of blood flow.

    03:54 Beta-2 (β2) adrenergic receptors are located in skeletal muscle and they can cause a vasodilation.

    04:02 That said, they are usually not engaged in normal physiology.

    04:06 You have to give us supra physiological dose of a drug to get this receptors to be in acted.

    04:13 So normally, our response is having a vasoconstriction in response the blood vessels of skeletal muscle.

    04:21 So you vasoconstrict them in terms of the sympathetic nervous systems response.

    04:26 Hopefully, you’ve looked now on the parasympathetic side and notice there is no intervention of blood vessels to the skin or to the muscle from the parasympathetic nervous system.

    04:40 That’s said, there are some relaxing factors that can be released.

    04:45 And some of this have been associated with some parasympathetic innervation especially in the facial region.

    04:52 The Autonomic Nervous System and the Lung.

    04:56 So what changes happen with the lung in regards to a sympathetic and parasympathetic nervous system? The main component with the lung are the bronchioles.

    05:06 If you dilated a bronchiole, what will get is an increase in a diameter.

    05:12 And if you have an increase in diameter, you'll have a reduction and a resistance and therefore more flow.

    05:19 And this sympathetic nervous system does just that by dilating bronchioles.

    05:26 It does that through beta-adrenergic receptors.

    05:29 The opposite response is a constriction.

    05:32 And this is mediated by this parasympathetic nervous system through muscarinic receptors.

    About the Lecture

    The lecture Effectors of the Autonomic Nervous System (ANS) by Thad Wilson, PhD is from the course Neurophysiology. It contains the following chapters:

    • Effectors of the ANS
    • ANS - Heart
    • ANS - Skin & Muscle Blood Vessels
    • ANS - Lung

    Included Quiz Questions

    1. Beta-1 adrenergic receptors
    2. Nicotinic receptors
    3. Muscarinic type 1 receptors
    4. Beta-2 adrenergic receptors
    5. Muscarinic type 2 receptors
    1. Vagus
    2. Facial
    3. Abducent
    4. Glossopharyngeal
    5. Occulomotor
    1. Alpha adrenergic
    2. Beta adrenergic type 1
    3. Nicotinic
    4. Muscarinic type 1
    5. Beta adrenergic type 2
    1. Beta adrenergic
    2. Nicotinic
    3. Muscarinic type 1
    4. Muscarinic type 2
    5. Alpha adrenergic

    Author of lecture Effectors of the Autonomic Nervous System (ANS)

     Thad Wilson, PhD

    Thad Wilson, PhD

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