Chapter 5

Question 1

What is indirect communication?

Answer 1

Indirect communication does not have cells physically touching each other instead involves a chemical messenger, binding a receptor on a cell. Its binding to whatever it can bind to. Communication via chemial signals

Question 2

What is direct communication

Answer 2

Direct communiction is very fast; allows for synchronized activation of cells, not good for long distance.

Question 3

What is paracrine messages?

Answer 3

Paracrine’s are side by side messages. Involves a paracrine message being relased binding a receptor to a cell next door.

Question 4

What is neurotransmitter?

Answer 4

Neurotransmitter – cell that releases the messenger is a neuron; target cell is a gland, muscles, or another neuron; needs to be fast for survival purposes.

Question 5

what is endocrine signaling?

Answer 5

Endocrine signaling utilize hormones. When hormones enter the blood stream have the ability to reach any cell in the body
Pro: can effect cells long away from the secretory glands
Con: slow, but not really slow just compared to neurotransmitter signaling

Question 6

When ever a endocrine cell secretes a hormone it will be either hydrophilic or hydrophobic. What is a hydrophilic messanger>

Answer 6

Hydrophilic messenger dissolve in the blood with no problem. Cannot dissolve throughout membrane because membrane is hydrophobic, so the receptor of the Hydrophilic messenger has to be located on the outside of the cell because it can not cross the membrane.

Question 7

What are hydrophobic messangers?

Answer 7

Hydrophobic messenger will not dissolve in water. Can cross the membrane so the receptor for the hydrophobic messanger are gonna be located on the inside of the cell, can have an affect on the inside of the cell, almost always a steroid hormone.

Question 8

What are ligands examples?

Answer 8

Paracrines, Neurotransmitters, and Hormones are ligands that bind receptors

Question 9

What are receptor proteins?

Answer 9

A target cell receives a signal because it has receptor proteins specific to it on the plasma membrane or inside the cell. Nonpolar signal molecules such as steroid hormones can penetrate the plasma membrane and interact with receptors inside the cell.

Question 10

What are reseptor properties?

Answer 10

Specificity: Each type of receptor only binds one type of ligand/molecule
Affinity: Strength of binding between a ligand and its receptor

Question 11

What is receptor affinity?

Answer 11

Receptor affinity are more attracted to the binding sites based on charges.

Question 12

What does receptor activation depend on?

Answer 12

Receptor activation depends on Concentration of ligand, Expression level of receptor, Affinity of receptor for ligand.

Question 13

What is the relationship between ligand concentration and receptor activation?

Answer 13

In general more ligand more receptor activated, but there are a number of receptors that can be activated. Once all receptors are bound by a ligand, it will not change anything by adding more.

Question 14

How can the number of receptors change?

Answer 14

Upregulation: Increase in receptor synthesis.
Downregulation: Decrease in receptor synthesis

Question 15

Describe drug interaction?

Answer 15

Every addictive drug available today takes advantage of pre-existing receptors in the human body. Binding of the drug to these receptors often activates a network of dopaminergic cells in the mesolimbic region of the brain that are involved in emotional reward. Every drug binds to a receptor. Mesolimbic region of brain deal with addiction, compulsive behavior, and reward using the hormone dopamine.
Overactive Mesolimibic regions equal scyhaphrania.
Not enough dopamine equal Parkinsons.

Question 16

Describe drug addiction?

Answer 16

Opiates: painkillers such as codeine, morphine, oxycodone, oxycontin, heroin, etc, activate natural G-protein coupled receptors for endorphins in the brain. Endorphin concentration is usually extremely low.Triggers receptor downregulation, as well as de-sensitization resulting from functional un-coupling of G-protein receptors to their effector molecule. Most addictive
Without endorphins any pain you feel would be way worse. Opiates release enormous quantities of endorphins and take down receptors for dopamine.

Question 17

What happens in nicotine addiction?

Answer 17

Nicotine has an extremely high affinity for acetylcholine receptors in the brain. It essentially out-competes acetylcholine for these receptors.
Cells that require acetylcholine for signaling respond by making more acetylcholine receptors, and releasing much more acetylcholine.
Now everything can bind to the receptors
Now it takes more nicotine to out compete the aetylcholine and metabolize it more quickly. There is also evidence that increased use of nicotine results in increased ability of an individual to metabolize nicotine. Results in a shorter half-life of the drug. It has also been suggested that nicotine up regulates extracellular mechanisms for degrading the drug.
Body becomes better at breaking down the drug (Tolerance- body’s ability to detoxify)

Question 18

What are the two mechanism for drug tolerance?

Answer 18

Mechanism for drug tolerance are; Pharmacokinetic tolerance: the result of lower concentrations of a drug actually reaching the receptor. Could be caused by degradation, or increased metabolism of the drug. (nicotine)
Pharmacodynamic tolerance: cellular mechanism that results in receptor down regulation (opiates), or upregulation (nicotine).

Question 19

What are agonist?

Answer 19

Agonist are ligands that bind to receptors and cause biological response.

Question 20

What are antagonist?

Answer 20

Antagonist are ligands that bind to receptors and DO NOT cause biological response.

Question 21

What are G proteins?

Answer 21

​G Proteins (molecular switches) are the most complex. Receptors could be coupled with G Proteins that are physically attached to proteins that will break off and bind with an effector protein (ion channel or enzyme). G proteins can open and close ion channels. When a G protein is bout to GTP; it is on. When GDP is bound, it is dead or inactive.

Question 22

What are lipophilic ligands?

Answer 22

Lipophilic ligands usually causes a change in gene expression (protein synthesis). They need a second messenger, the first is the ligand, but it cant cross the non polar membrane. Is hydrophobic.

Question 23

What are lipophobic ligands

Answer 23

Lipophobic ligands are hydrophillic ligands.

Question 24

What are the pros and cons of direct and indirect signaling?

Answer 24

Pro: Very fast: Allows for synchronized activation of cells, to activate them in the correct order, for short distance
Con: Not good for long distance signaling, would involve to many cells