![[dr. bob]](/dr-bob-sm.gif)
Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 13 of 13. This is the beginning of the thread.
Posted by Janelle on March 23, 2002, at 21:00:01
The responses to my "TCA and Receptors" Post above focussed solely on TCA's, so I thought I'd post the RECEPTOR question separately here:
I'm not sure I'm getting the concept of the receptor - from the spelling of the word I associate it with *receiving*, so I come away with the idea that receptors receive things. Yet, when I read various threads on here explaining things, it sounds like receptors RELEASE things (e.g. do receptors release histamines?)
What do receptors do? Ack ... I'm confused.
Posted by IsoM on March 23, 2002, at 22:30:04
In reply to Dangling question re RECEPTORS:, posted by Janelle on March 23, 2002, at 21:00:01
I hope, Janelle, that I'm not overdoing this for you. If you've got a printer, print out some of this info so you can peruse it at a leisurely pace later.
Here again is a site that talks about synapses & receptors with diagrams.
http://www.ultranet.com/~jkimball/BiologyPages/S/Synapses.htmlYou may find this reasonably simple explanation of the organisation of the nervous system helpful.
http://www.ultranet.com/~jkimball/BiologyPages/P/PNS.html#Organization_of_the_Nervous_SystemI really think Kimball's Biology Pages are good for teaching & understanding the basics of biology in easy to understand terms. If you do like these pages, here's the home page.
http://www.ultranet.com/~jkimball/BiologyPages/If you click on the letter of the word you'd like to know more about, it'll take you to an index of all the words beginning with that letter. Just scroll down the page to find the word you want. Much of it isn't about the human body, but you'll find what you need here,
Posted by Janelle on March 23, 2002, at 22:44:32
In reply to Re: Dangling question re RECEPTORS: » Janelle, posted by IsoM on March 23, 2002, at 22:30:04
ISO - I clicked on those three great links you provided but still couldn't find a simple, basic definition of a receptor! When I clicked on "R" in that bio textbook, Receptor wasn't even listed!
Can you possibly explain what a receptor is (does it just receive chemicals or does it release them also, what does the darn thing do?!!!)
Posted by IsoM on March 23, 2002, at 23:20:13
In reply to ISO: thx, but still can't find simple def of recep » IsoM, posted by Janelle on March 23, 2002, at 22:44:32
Okay, I'll explain & I don't mind but I just thought diagrams helped. Wish I could use pictures in this forum to make it easier.
A receptor is the end of the nerve cell (neuron) that receives information (stimuli or neurotransmitter) from another nerve cell. Think of it as a river flowing downstream. One neuron releases neurotransmitters that diffuse across the gap (synapse) to the receiving end (the receptor) of the next neuron downstream. All neurons have two ends - the receiving ends (receptor) with receptor sites on that end, & the transmitting end.
Neurons don't quite touch each other. The small space inbetween them is where all the neurotranmitter activity happens. If you've ever seen a picture of a typical nerve cell, it has many ends from the main body & from the other end (like long tail) it has what looks a bit like roots.
The many-branches of the head is the dendrites (where the receptors are) & the root-like bottom is the axon terminal where the neurotransmitters are contained. I'll give you a link with a picture to help you. I hope this makes more sense.
Neural Diagram: http://www.mhhe.com/socscience/intro/ibank/ibank/0002.jpg
Synapses: http://www.mhhe.com/socscience/intro/ibank/ibank/0003.jpg
Posted by fachad on March 24, 2002, at 3:20:22
In reply to ISO: thx, but still can't find simple def of recep » IsoM, posted by Janelle on March 23, 2002, at 22:44:32
Janelle,
Here's my crack at a simple definition of a receptor.
A receptor is a thing on a nerve cell that is activated by a chemical neurotransmitter. Always think of receptors and neurotransmitters as a pair. Serotonin is a chemical neurotransmitter, which acts at a serotonin receptor.
Very simply put, think of a receptor as a keyhole, and a neurotransmitter as a key that fits into that keyhole.
A drug can bind with a receptor because its structure is similar enough to the natural neurotransmitter to fit into the keyhole. It can fit in, and act like the drug, like a master key of a locksmith. In that case it is an "agonist" or assister of the neurotransmitter / receptor pair.
A drug can also bind with a receptor, not act like the neurotransmitter, and block the natural action of the neurotransmitter, like someone pouring glue into a keyhole, making it impossible for the lock to be used. In this case it is an antagonist.
I guess an analogy would be a taste bud. You have them on your tongue, and they are taste receptors. There are "sweet" receptors, "salty" receptors, etc. The similarity is that taste buds, like receptors, are "organs" that respond to one specific thing. For taste buds, its sweet, salty, etc. For receptors, its NE, 5HT, ACH, etc.
The difference between taste buds and receptors in your nervous system is that all taste buds do one thing - send taste sensations to your brain.
But receptors can do just about anything. They can excite the nerve downstream of the receptor. They can inhibit the nerve downstream of the receptor. They can excite or inhibit the nerves upstream of the receptor. The can cause the release of the chemical that activates them, or they can inhibit the release of the chemical that activates them. They can cause the release of other transmitters. There are a huge number of possibilities and that is why it seems so complicated to you.
But basically the keyhole / chemical key analogy is enough to roughly understand what is going on.
> ISO - I clicked on those three great links you provided but still couldn't find a simple, basic definition of a receptor! When I clicked on "R" in that bio textbook, Receptor wasn't even listed!
>
> Can you possibly explain what a receptor is (does it just receive chemicals or does it release them also, what does the darn thing do?!!!)
Posted by Janelle on March 25, 2002, at 16:18:47
In reply to Simple Definition of Receptor » Janelle, posted by fachad on March 24, 2002, at 3:20:22
All I want to know is yes or no - can receptors both RECEIVE and SEND chemicals?
I ask because I associate the word receptor with the word receive, both seem to have the same root.
However, from what I've read on this board, it sounds like receptors can BOTH receive and SEND?
For example, Fachad wrote "receptors can do just about anything .... They can cause the release of the chemical that activates them, or they can inhibit the release of the chemical that activates them. They can cause the release of other transmitters."
Based on this, I get the impression that receptors can do BOTH - receive and cause the release of chemicals? If this is true, than the name receptor is misleading imho.
Thanks to whoever can provide a yes/no answer to my basic question!
Posted by IsoM on March 25, 2002, at 19:09:12
In reply to YES/NO question about RECEPTORS!, posted by Janelle on March 25, 2002, at 16:18:47
Receptors are on the end of the nerve cell that RECEIVES a message. The message is received in the form of neurotransmittersu sent from the other end of an adjacent nerve cell. Receptors don't send, they receive only.
But the neurotransmitters that the receptor receives do not stay locked into the receptor plugs on the receptor end. Otherwise the same signal would be continuously sent. After the message (from the neurotransmitters) is received by the receptor, the receptor will release the neurotransmitter molecules & don't continuing holding them. They let go. The molecules of neurotransmitters will then fade back into the sending end of the other nerve cell.
I'll give a human illustration. You are a receptor, your house is nerve cell, your door is the receptor end. You receive a message in the form of a letter (the equivalent of neurotrasmitters) from another house. After receving & reading the letter, you toss the paper outside to be recycled. You pass the information along to the other members of your family in the house (cell). If the message needs to travel further to another house (nerve cell), a letter (neurotransmitters) will be sentfrom the back door. You did receive the message but you did release something too - the paper the letter was on after you got the message.
Same with nerve cells. The receptor ends receives a message, transmitts it along the axon to the other end which will send it to the next nerve cell & its receptor. But the receptors don't hold on to the neurotransmitter molecules it gets the message from, no more than you hold on to every paper. The paper is recycled again - and so are neurotransmitters. The receptor has "received a message" but has "released" the form the message came in - neurotransmitters, back to the other cell that sent them in the first place.
Oh, please, please - I hope this makes it clearer.
Posted by fachad on March 25, 2002, at 19:51:27
In reply to YES/NO question about RECEPTORS!, posted by Janelle on March 25, 2002, at 16:18:47
NO. They can only receive chemicals.
But that is misleading because they (receptors) do not exist in the nervous system as isolated pieces. They are connected to a nervous system in an integrated, dynamic, living body.
Think about a thermometer that is a part of a thermostat that is part of a climate control system that is part of your house.
The only thing the thermometer "does" is sense temperature. But it is wired into a thermostat that is connected to a central heat system. So the thermometer, in a strict, literal sense only passively senses temperature.
But if you look at the big picture you might find yourself saying that the thermometer “turned on” the heat. The thermometer does not really turn on the heat, but as a result of the thermometer sensing that the temperature is too low, the thermostat sends a signal which triggers the central heat to be turned on. Conversely, when the temperature is sensed as being too high by the thermometer, it triggers a series of events that result in the heat being shut off.
In the same way receptors "only" passively receive neurotransmitters, which means the strict literal answer to your question is "NO".
But within the nervous system that is within your body, lots of things happen as a consequence of a receptor passively receiving a neurotransmitter. A receptor being activated can transmit a nerve impulse down the chain throughout your body. A receptor being activated can trigger a reaction that releases another neurotransmitter, or inhibits another neurotransmitter, which turns on some receptors, and turns off others. And on and on....
Posted by Janelle on March 25, 2002, at 20:46:21
In reply to YES/NO answer about RECEPTORS! (sort of) » Janelle, posted by fachad on March 25, 2002, at 19:51:27
Posted by IsoM on March 25, 2002, at 23:00:20
In reply to Thanx, but forget it, I give up! (nm), posted by Janelle on March 25, 2002, at 20:46:21
Ha! I'm a stubborn teacher! Get back in class & sit down. :-)
SHORT ANSWER:---------------------------------
Simple comparison - a garden hose. Water goes in one end, comes out other end. The end of the hose attached to tap is the receptor - it receives water. Forget neurotransmitters & all. Just think message=water. One end receives the message, the other end transmits it. Get that down, stick to that, and after a while you can add on further explanations.
END OF SHORT ANSWER:-----------------------------Too much info & trying to link it all will induce brain overload, sparks will fly, & sadly Janelle will short-circuit with smoke & fire-works from all sides. Stick to basics till they feel comfortable. Bit by bit, the other things will make sense. It's really how everybody learns. You need a framework of knowledge to add pieces on. If the framework isn't sound, adding on more will make the whole thing crumble. Remember, it took most of us years to grasp it all.
Posted by IsoM on March 25, 2002, at 23:01:20
In reply to Thanx, but forget it, I give up! (nm), posted by Janelle on March 25, 2002, at 20:46:21
Posted by Janelle on March 26, 2002, at 1:13:49
In reply to One More Very *Short* Answer » Janelle, posted by IsoM on March 25, 2002, at 23:00:20
Iso, thank you so much for your kindness and patience and really wanting me to learn the basics of this stuff! I appreciate it and it means a lot to me!
Okay, I follow your garden hose comparison. Water goes in one end, comes out other end. The end of the hose attached to tap is the receptor - it receives water. So, after receiving the water, the receptor *lets go* of it so to speak, the water travels through the hose (through the neuron; is the hose analogous to a neuron?) and the other end (of the hose or of the neuron) transmits it?
BTW, you are absolutely right - "too much info & trying to link it all will induce brain overload, sparks will fly, & sadly Janelle will short-circuit with smoke & fire-works from all sides!" I am feeling OVERWHELMED with all the info I've received, so I gotta stop asking questions that will yield technical responses! :-)
Posted by IsoM on March 26, 2002, at 3:36:24
In reply to ISO, okay, trying ONE more time with this: » IsoM, posted by Janelle on March 26, 2002, at 1:13:49
Yes, the hose is the neuron. But remember, I said "water = message sent", the water is the message passing along, it's NOT the neurotransmitters. In the actual neuron, the neurotransmitter isn't the 'message'. It's simply the means to pass the message along.
The message travels through the neuron (water through the hose) by electrically charged ions (you can learn more about that later - not important now). The neurotransmitters are only to be found at the space between the neurons where they don't quite touch.
A garden hose isn't the best comparison because if all the hoses weren't tightly screwed to each other, the water (message) would leak out. Neurons don't actually touch each other but almost do (think of it like a brass connection between different hoses). That small gap or space between where neurons connect is the synapse. And that's where neurotransmitters act. They are the means to pass the message from one neuron to another.
Just digest that bit, if understandable, & when you feel comfortable with that, you can add more on.
This is the end of the thread.
Psycho-Babble Medication | Extras | FAQ
Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.org
Script revised: February 4, 2008
URL: http://www.dr-bob.org/cgi-bin/pb/mget.pl
Copyright 2006-17 Robert Hsiung.
Owned and operated by Dr. Bob LLC and not the University of Chicago.