Chapter 28- Chemical Messengers

an amino acid derived neurotransmitters

1) acetylcholine 2) dopamine 3) histamine

what are the 3 classes of hormones?

1) amino acid derivatives 2) peptide and protein hormones 3) steroid hormones

what are the 3 major chemical classes of neurotransmitters?

1) amino acid derived 2) amino acids 3) peptides

what are 3 ACH agonists?

1) black widow spider venom-indirect 2) nicotine-direct 3) sarin-indirect

what are 2 ACh antagonists?

1) botox 2) atropine

what are 2 ways that the neurotransmitters are removed from the synapse

1) diffuse away and most are then degraded 2) reuptake by the presynaptic neuron and placed in storage until it is needed again (some could be metabolized in the synapse)

What are the 2 types of cell signaling?

1) direct local signaling 2) indirect local or distant signaling

what are the 2 major chemical messengers that transmit messages in our bodies?

1) endocrine system 2) nervous system

amino acid neurotransmitters

1) glutamate 2) gamma-aminobutyric acid (GABA)

sequence events upon hormone binding to the receptor of the G protein GTP complex

1) hormone binds to the receptor on the cells surface 2) G protein binds to the hormone-receptor complex and then binds to GTP instead of GDP 3) the GTP bound G protein is now converted into the active form and activates adenylate cyclase 4) adenylate cyclase converts ATP into cAMP 5) cAMP serves as the second messenger

what are the events in synaptic transmission?

1) nerve impulses trigger the synaptic vesicles to move to the presynaptic terminal 2) neurotransmitters are released into the synapse, diffuse and bind to receptors at the postsynaptic terminal 3) activates the neuron

what are 3 three types of indirect local signaling?

1) paracrine signaling 2) autocrine signaling 3) neurotransmission

what are the general events in cell signaling? (general process)

1) signaling cell releases the chemical messengers 2) chemical messengers are carried in the extracellular fluid for a short or long distance 3) chemical messengers bind to their receptors on or inside target cells, which 4) trigger a biological response in the target cell

What are the 2 cell types involved in intercellular communication?

1) signaling cells-send electrical signals to another cell 2) target cells-receive the signals, resulting in a biological response

what are the 3 membrane proteins that make up the G protein GTP complex?

1) the receptor that binds to the hormone 2) a guanine nucleotide-binding protein (G protein) 3) adenylate cyclase-enzyme that generates the 2nd messenger

what are the 2 peptide and protein hormones you need to know?

1) vasopressin ( 9 aa and 1 disulfide bond) 2) insulin

what are the 4 subunits of PKA (protein kinase A which regulates metabolism)?

2 inactive catalytic subunits and 2 regulatory subunits

degradation of acetylcholine

ACh is hydrolyzed into acete and choline by acetyl cholinesterase; choline is reuptaken into presynaptic neuron to produce ACh; the rapid clearly of ACh is essential for proper muscle function

once the emergency has passed, the hormone no longer binds to the receptor, all 3 membrane proteins dissociate and cAMP is converted back to ?

ATP

alkaloid extracted from nightshade plant; competes with ACh at receptors; used as a drug in medicine for paralytic effects; dilates pupils; can be used as antidote against sarin poisoning

Atropine

these drugs can block the reuptake of dopamine resulting in a longer lifetime in synapse

cocaine and amphetamine

what are the 2 types of steroid hormones?

cortical steroids and sex hormones

produced by the cortex of the adrenal glands; regulate glucose metabolism and inhibit inflammation

cortisone and cortisol (glucocorticoids)

signaling molecules located on the surface of the signaling cell bind to receptors on the surface of target cells; the binding triggers response in target cells

direct local signaling

signaling molecules pass from signaling cell to target cell through the gap junction

direct local signaling

when the signaling cell and target cell are in direct contact

direct local signaling

produced from tyrosine in the nerve cells of the midbrain and acts as a natural stimulant to give us energy and feelings of enjoyment

dopamine

catecholamine examples

dopamine, norepinephrine and epinephrine

a system of specialized cells, tissues, and ductless glands that excrete hormones and share responsibility with the nervous system for maintaining constant internal body conditions (homeostasis) and responding to changes in the environment

endocrine system

the chemical messengers are hormones that circulate in the blood

endocrine system

one of the major neuropeptides that bind to the opiate receptor

enkephalin

peptide neurotransmitter

enkephalins

mainly produced and released by the adrenal gland when we need an instant response to danger; works through the G protein-GTP complex; fight or flight`

epinephrine

excess dopamine=? lack of dopamine=?

euphoria and schizophrenia parkinson's disease

glands that have ducts (example: sweat glands)

exocrine glands

specialized pores made of proteins that directly connect the cytoplasm of cells

gap junctions

synthesized in the nerve cells in the hypothalamus from the aa histidine; produced by the immune system in response to pathogens and invaders; when combined with receptors=allergic reaction

histamine

derived from tyrosine; thyroxine, epinephrine, norepinephrine, and dopamine

hormones derived from amino acids

cannot cross the hydrophobic cell membrane; bind to the receptors on cell surfaces, which results in the formation of a second messenger

hydrophilic hormone signal delivery (polypeptide and amino acid derivative)

circulate freely in blood, do not enter the cell through lipid bilayer, bind to surface receptors, need a second messenger

hydrophilic hormones

travel in blood binding to special carrier proteins, enter cells-through the cell membrane, bind to intracellular receptors to cause a response

hydrophobic hormones

what are the major endocrine glands in the body?

hypothalamus, pituitary gland, thyroid, parathyroid, adrenal glands, and the pancreas, ovaries, and testes

signaling cells secrete chemical messengers which travel to target cells via blood circulation; ability of a cell to respond to the hormone or not depends on the presence or absence of receptors specific to that hormone

indirect distant signaling

when the signaling cell and target are close but not in direct contact or far apart, respectively

indirect local or distant signaling

when signaling cells and target cells are close together, but not in direct contact with each other; signal cells secrete a chemical messenger which travels only a short distance to the target cell

indirect local signaling

contains a total of 51 amino acids and is released by the pancreas in response to high concentrations of glucose in the blood

insulin

how is cAMP converted back to ATP?

it is converted to AMP by phosphodiesterase and then back to ATP

an alkaloid and an effective but addictive pain-killer

morphine

the chemical messengers are neurotransmitters that carry signals from one nerve cell to another nerve cell, or to their targets

nervous system

basic unit; has a cell body, a nucleus, an axon, and dendrites

neuron (nerve cell)

occurs in the synapse of the nervous system; electrical signal travels along a neuron triggers the release of neurotransmitter into the synapse to stimulate the target cells

neurotransmission

chemical messengers produced by neurons; transmit an impulse from a nerve cell to a target cell-another nerve cell, a muscle cell, or gland

neurotransmitters

water soluble chemical messengers synthesized in neurons and stored in synaptic vesicles

neurotransmitters

binds to the ACh receptor; at low does is an agonist but at high doses is an antagonist

nicotine

lack a receptor, so their is no response

non-target cells

consist of mixtures of synthetic estrogen and progestin; tricks the body into thinking it is already pregnant so ovulation is inhibited

oral contraceptives

chemical messengers affect adjacent cells of different types; signaling cells regulate their neighbors

paracrine signaling

the largest class of hormones; range from just a few amino acids to several hundred of amino acids; some have quaternary structures

peptide and protein hormones

is a synthetic corticosteroid, derived from cortisone; used for reducing inflammation, treating asthma and RA

prednisone

the major female sex hormones

progesterone, 2 estrogens-estradiol, and estrone (metabolized form of estradiol)

a protein molecule with which a chemical messenger binds specifically to; can be located on the cell surface or inside cells

receptors

indirect-an irreversible competitor of ACh; inhibits ACH by forming a covalent bond with serine residues at the active site; causes excess ACH at neuromuscular junction, causing paralysis of the muscles which are needed for breathing and heart beating

sarin

a chemical messenger released inside a cell when the first messenger binds to a receptor on the cell surface of target cells

second messenger

can enter cells through the hydrophobic lipid bilayer; binds to cytoplasmic receptor that carries the hormone to genes in the nucleus to change gene expression

steroid hormone signal delivery

hydrophobic chemical messengers; produced from cholesterol-4 connected rings

steroid hormones

a small, narrow gap where the tip of a presynaptic neuron and a postsynaptic cell lie adjacent to each other

synapse

what is the synthesis of acetylcholine

synthesized in presynaptic neurons; synthesized from choline and acetyl coenzyme A in a reaction catalyzed by the choline acetyltransferase

a specific receptor for the chemical messenger needs to be present. the binding of chemical messengers initiates a response through a signal pathway

target cells

the two most important male sex hormones

testosterone and androsterone-metabolized form of testosterone that is excreted

synthesized from glutamate; most common inhibitory neurotransmitter; produces a calming effect; tranquilizer drugs are agonists

GABA-gamma aminobutyric acid

inactive form of G protein ? active form of G protein ?

GDP GTP

produced in the hypothalamus and stored in the pituitary gland; causes the retention of body water by decreasing urine volume, and elevates blood volume and blood pressure

vasopressin aka antidiuretic hormone(ADH)

neurotransmitters mode of signal transduction is similar to that of

water soluble or insoluble(cannot get into the cell membrane) hormones

iodine-containing hormone; secreted by the thyroid gland, increases metabolism, important for growth and development

thyroxine

synthesis of catecholamines from tyrosine

tyrosine(hydroxylation)->DOPA(decarboxylation)->DOPAMINE(hydroxylation)->norepinephrine(methylation)->epinephrine

an organic compound that has a catechol (benzene with two hydroxyl side groups) and an amine group

catecholamines

amine neurotransmitter, containing N atoms as alkyl ammonium ions (quaternary amines); produced in presynaptic neuron and stored in vesicles; cholinergic nerves

acetylcholine (ACh)

neurotransmitter that binds to the receptor and cause activation

agonists

neurotransmitter that binds to the receptor but stops or prevents activation

antagonists

secreted chemical messengers diffused back to the signaling cells; the signaling cell is also the target cell; the signaling cell regulates itself

autocrine signaling

activates the release of excess ACH; synapse is flooded with ACh resulting in muscle cramps and spasms; indirect agonist

black widow spider venom

blocks ACh release by binding irreversible to the presynaptic neuron where ACh would by released; causes reduction of muscle activity (muscle paralysis)

botox

how is cAMP a positive allosteric regulator of PKA?

cAMP binds to the regulatory subunits of PKA and dissociates them from the catalytic subunits. The catalytic subunits are now active and carry out metabolism