Chapter 28: Chemical Messengers: Hormones, Neurotransmitters, and Drugs

Dopamine

________ plays a role in the brain in processes that control movement, emotional responses, and the experiences of pleasure and pain.

Neurotransmitter

________ is a chemical messenger that travels between a neuron and a neighbouring neuron or other target cell to transmit a nerve impulse.

GDP

________ (guanosine diphosphate) associated with the G protein is exchanged for GTP (guanosine triphosphate) from the cytosol.

Amitriptyline

________ is representative of the tricyclic antidepressants, which were the first generation of these drugs.

Choline

________ is absorbed back into the presynaptic neuron, where new acetylcholine is synthesized.

Fluoxetine

________ represents the newest class of antidepressants, the selective serotonin re- uptake inhibitors (SSRI)

Pharmacologists

________ classify some drugs as agonists- substances that act to produce or prolong the normal biochemical response of a receptor.

Adenylate cyclase

________ catalyses production within the cell of the second messenger- cyclic AMP- from adenosine triphosphate (ATP)

Acetylcholine

________ crosses the synapse and binds to receptors on the postsynaptic neuron, causing a change in membrane permeability to ions.

bloodstream

Epinephrine, a hormone carried in the ________, binds to a receptor on the surface of a cell.

water soluble molecules

The polypeptide and amine hormones are ________ and can not cross the hydrophobic cell membranes.

Receptor

________ is a molecule or portion of a molecule with which a hormone, neurotransmitter, or other biochemically active molecule interacts to initiate a response in a target cell.

Phenelzine

________ is a monoamine oxidase (MAO) inhibitor, one of a group of medications that inhibit the enzyme that breaks down monoamine neurotransmitters.

Cyclic AMP

________ initiates reactions that activate glycogen phosphorylase, the enzyme responsible for release of glucose from storage.

hydrophobic molecules

Because the cell is surrounded by a membrane composed of ________, only nonpolar, ________ can move across it on their own.

Vesicles

________ move to the cell membrane, fuse with it, and release their acetylcholine molecules (several thousand molecules from each ________)

sleep wake

It is also widely distributed in the brain, where it plays a role in the ________ cycle, learning, memory, and mood.

Hormones

________ are the chemical messengers of the endocrine system.

external source

A drug is any molecule that alters normal functions when it enters the body from a(n) ________.

antagonists substances

Other drugs are classified as ________ that block or inhibit the normal response of a receptor.

oversupply of dopamine

A(n) ________ is associated with schizophrenia, and an undersupply results in the loss of fine motor control in Parkinsons disease.

steroid hormones

The ________ are nonpolar, so they can enter the cell directly by diffusion; this is one of the ways a hormone delivers its message.

chemical nature

The signal enters the cell in ways determined by the ________ of the hormone.

Serotonin

________ is important in mood- control pathways and functions more slowly than other neurotransmitters; slowing its re- uptake often improves mood in depressed patients.

Endocrine system

________ is a system of specialized cells, tissues, and ductless glands that secretes hormones and shares with the nervous system the responsibility for maintaining constant internal body conditions and responding to changes in the environment.

G protein

In general, three membrane- bound proteins participate in release of the second messenger: (1) the receptor and (2) a(n) ________ (a member of the guanine nucleotide- binding protein family) that transfer the message to (3) an enzyme.

re uptake of serotonin

The tricyclics prevent the ________ and norepinephrine from within the synapse.

Neurotransmitters

________ are synthesized in presynaptic neurons and stored there in vesicles for release when needed.

Acetylcholine

________ is a neurotransmitter responsible for the control of skeletal muscles.

Fluoxetine

________ (Prozac) has rapidly become the most widely prescribed drug for all but the most severe forms of depression.

Acetylcholine

________ is synthesized in presynaptic neurons and stored in their vesicles.

In general, three membrane-bound proteins participate in release of the second messenger

(1) the receptor and (2) a G protein (a member of the guanine nucleotide-binding protein family) that transfer the message to (3) an enzyme

Adenylate cyclase catalyses production within the cell of the second messenger

cyclic AMP-from adenosine triphosphate (ATP)

The evidence comes from the different modes of action of three families of drugs used to treat depression

amitriptyline, phenelzine, and fluoxetine

receptor

a molecule or portion of a molecule with which a hormone, neurotransmitter, or other biochemically active molecule interacts to initiate a response in a target cell.