Neurotransmitters and the Endocrine System

Chemical MessengersChemical Messengers

Systems of Coordination Animals have two systems of coordination, Animals have two systems of coordination,

the the nervous systemnervous system and the and the endocrine endocrine system.system.

The nervous system coordinates rapid The nervous system coordinates rapid responses to external stimuli. responses to external stimuli.

The endocrine system controls slower, The endocrine system controls slower, longer lasting responses to internal stimuli.longer lasting responses to internal stimuli.

Activity of both systems is integrated.Activity of both systems is integrated.

Chemical messengers

3 types of chemical messengers:3 types of chemical messengers: Neurotransmitters (NTs)Neurotransmitters (NTs)

Come from NeuronsCome from Neurons EndorphinsEndorphins

Various SourcesVarious Sources HormonesHormones

Come from glands (the Endocrine System)Come from glands (the Endocrine System)

Review: Synapse

What is a synapse?What is a synapse? A synapse is the “gap” between the A synapse is the “gap” between the

axon of one nerve and the dendrite of axon of one nerve and the dendrite of the next one. the next one.

NT’s travel through the SynapseNT’s travel through the Synapse

Review: Neurotransmitters

Chemical messengers released from Chemical messengers released from neurons into the synapseneurons into the synapse

There are dozens of different There are dozens of different neurotransmittersneurotransmitters (NT) in the neurons of (NT) in the neurons of the body.the body.

NTs can be either NTs can be either excitatoryexcitatory or or inhibitoryinhibitory

What happens to NTs after they give their signal? They may return to their starting vesicles in They may return to their starting vesicles in

the axon button – “reuptake”the axon button – “reuptake” They may be absorbed and broken down by They may be absorbed and broken down by

the bodythe body

Mnemonics for remembering our 4 NTs and 4 hormones NTs: SAND = Serotonin, Acetylcholine, NTs: SAND = Serotonin, Acetylcholine,

Norepinephrine, DopamineNorepinephrine, Dopamine Hormones: COME = Cortisol, Oxytocin, Hormones: COME = Cortisol, Oxytocin,

Melatonin, EpinephrineMelatonin, Epinephrine

1. Serotonin Important in mood, sleep, aggression, Important in mood, sleep, aggression,

impulsive behavior, movement, appetite, impulsive behavior, movement, appetite, perception, attention and learning. perception, attention and learning.

In the spinal cord, serotonin is inhibitory in In the spinal cord, serotonin is inhibitory in pain pathways.pain pathways.

Serotonin level is related to carbohydrate Serotonin level is related to carbohydrate intake.intake.

Undersupply linked to depression; Prozac Undersupply linked to depression; Prozac raises serotonin levelsraises serotonin levels

2. Acetylcholine (ACh)

Controls motion; plays a role in attention & Controls motion; plays a role in attention & memory. memory.

Usually excitatory. Usually excitatory. Anything that interferes with acetylcholine Anything that interferes with acetylcholine

will produce paralysis. will produce paralysis. Alzheimer’s Disease results from Alzheimer’s Disease results from

degeneration of the cells that produce degeneration of the cells that produce acetylcholine.acetylcholine.

3. Norepinephrine (noradrenaline)

Important in wakefulness, learning, and Important in wakefulness, learning, and mood. mood.

Can be excitatory or inhibitory. Can be excitatory or inhibitory. Released during stress reactions (fight Released during stress reactions (fight

or flight; sympathetic nervous system) or flight; sympathetic nervous system) Imbalance associated with depression.Imbalance associated with depression.

4. Dopamine

Important in movement, attention, Important in movement, attention, learning and the regulation of emotional learning and the regulation of emotional response. response.

Necessary for the experience of Necessary for the experience of reward/pleasure. reward/pleasure.

Usually inhibitoryUsually inhibitory Excess associated with schizophrenia; Excess associated with schizophrenia;

decrease associated with Parkinson’s decrease associated with Parkinson’s Disease.Disease.

Neural Communication

Serotonin Pathways Dopamine pathways

Endorphins

Another chemical messengerAnother chemical messenger Naturally occurring substances that Naturally occurring substances that

act like morphine in the body. act like morphine in the body. Reduce pain and increase pleasure.Reduce pain and increase pleasure. Some endorphins act as NTs, some Some endorphins act as NTs, some

act on NTsact on NTs

The Endocrine System (hormones)

Endocrine SystemEndocrine System the body’s “slow” the body’s “slow”

chemical chemical communication communication systemsystem

a set of glands a set of glands that secrete that secrete hormones into the hormones into the bloodstreambloodstream

Hormones

Hormones act through the bloodstream, Hormones act through the bloodstream, instead of being released by neuronsinstead of being released by neurons

Hormones are slower but longer lasting Hormones are slower but longer lasting than NTsthan NTs

Key HormonesHormoneHormone GlandsGlands FunctionFunction

CortisolCortisol AdrenalsAdrenals Stress; MemoryStress; Memory

OxytocinOxytocin PituitaryPituitary AttachmentAttachment

MelatoninMelatonin PinealPineal Regulates sleepRegulates sleep

Epinephrine Epinephrine (Adrenaline)(Adrenaline)

AdrenalsAdrenals Fight or flight; Fight or flight; emotion; stressemotion; stress

A spider’s venom causes paralysis. The venom probably affects:

A.A. SerotoninSerotonin

B.B. EndorphinsEndorphins

C.C. NorepinephrineNorepinephrine

D.D. AcetylcholineAcetylcholine

Prozac increases the availability of serotonin in the brain. Prozac is a(n):

A. AgonistA. Agonist B. AntagonistB. Antagonist C. NeurotransmitterC. Neurotransmitter