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Connections of parasympathetic division of the autonomic nervous system

This diagram shows the spinal cord and has different central nerves emerging from it. The central nerves target different effector organs that are listed on the right.
Neurons from brain-stem nuclei, or from the lateral horn of the sacral spinal cord, project to terminal ganglia near or within the various organs of the body. Axons from these ganglionic neurons then project the short distance to those target effectors.

Chemical signaling in the autonomic nervous system

Where an autonomic neuron connects with a target, there is a synapse. The electrical signal of the action potential causes the release of a signaling molecule, which will bind to receptor proteins on the target cell. Synapses of the autonomic system are classified as either cholinergic    , meaning that acetylcholine (ACh)    is released, or adrenergic    , meaning that norepinephrine    is released. The terms cholinergic and adrenergic refer not only to the signaling molecule that is released but also to the class of receptors that each binds.

The cholinergic system includes two classes of receptor: the nicotinic receptor    and the muscarinic receptor    . Both receptor types bind to ACh and cause changes in the target cell. The nicotinic receptor is a ligand-gated cation channel    and the muscarinic receptor is a G protein–coupled receptor    . The receptors are named for, and differentiated by, other molecules that bind to them. Whereas nicotine will bind to the nicotinic receptor, and muscarine will bind to the muscarinic receptor, there is no cross-reactivity between the receptors. The situation is similar to locks and keys. Imagine two locks—one for a classroom and the other for an office—that are opened by two separate keys. The classroom key will not open the office door and the office key will not open the classroom door. This is similar to the specificity of nicotine and muscarine for their receptors. However, a master key can open multiple locks, such as a master key for the Biology Department that opens both the classroom and the office doors. This is similar to ACh that binds to both types of receptors. The molecules that define these receptors are not crucial—they are simply tools for researchers to use in the laboratory. These molecules are exogenous    , meaning that they are made outside of the human body, so a researcher can use them without any confounding endogenous    results (results caused by the molecules produced in the body).

The adrenergic system also has two types of receptors, named the alpha (α)-adrenergic receptor    and beta (β)-adrenergic receptor    . Unlike cholinergic receptors, these receptor types are not classified by which drugs can bind to them. All of them are G protein–coupled receptors. There are three types of α-adrenergic receptors, termed α 1 , α 2 , and α 3 , and there are two types of β-adrenergic receptors, termed β 1 and β 2 . An additional aspect of the adrenergic system is that there is a second signaling molecule called epinephrine    . The chemical difference between norepinephrine and epinephrine is the addition of a methyl group (CH 3 ) in epinephrine. The prefix “nor-” actually refers to this chemical difference, in which a methyl group is missing.

Questions & Answers

Discuss the differences between taste and flavor, including how other sensory inputs contribute to our  perception of flavor.
John Reply
taste refers to your understanding of the flavor . while flavor one The other hand is refers to sort of just a blend things.
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While taste primarily relies on our taste buds, flavor involves a complex interplay between taste and aroma
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omeprazole
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Nency Reply
Not really sure
Eli
to drain extracellular fluid all over the body.
asegid
The lymphatic system plays several crucial roles in the human body, functioning as a key component of the immune system and contributing to the maintenance of fluid balance. Its main functions include: 1. Immune Response: The lymphatic system produces and transports lymphocytes, which are a type of
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to transport fluids fats proteins and lymphocytes to the blood stream as lymph
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Oyindarmola Reply
Anatomy is the identification and description of the structures of living things
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Oyerinde Reply
Anatomy is the study of the structure of the body, while physiology is the study of the function of the body. Anatomy looks at the body's organs and systems, while physiology looks at how those organs and systems work together to keep the body functioning.
AI-Robot
what is enzymes all about?
Mohammed Reply
Enzymes are proteins that help speed up chemical reactions in our bodies. Enzymes are essential for digestion, liver function and much more. Too much or too little of a certain enzyme can cause health problems
Kamara
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Prince
how does the stomach protect itself from the damaging effects of HCl
Wulku Reply
little girl okay how does the stomach protect itself from the damaging effect of HCL
Wulku
it is because of the enzyme that the stomach produce that help the stomach from the damaging effect of HCL
Kamara
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function of digestive
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37 degrees selcius
Xolo
37°c
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36.5
Simon
37°c
Iyogho
the normal temperature is 37°c or 98.6 °Fahrenheit is important for maintaining the homeostasis in the body the body regular this temperature through the process called thermoregulation which involves brain skin muscle and other organ working together to maintain stable internal temperature
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Wulku
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anaemia is the decrease in RBC count hemoglobin count and PVC count
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acid
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Organ Systems Of The Human Body (Continued) Organ Systems Of The Human Body (Continued)
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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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