Neurotransmitters and the Endocrine System Chemical Messengers

Systems of Coordination Animals have two systems of coordination, the nervous system and the endocrine system. Animals have two systems of coordination, the nervous system and the endocrine system. The nervous system coordinates rapid responses to external stimuli. The nervous system coordinates rapid responses to external stimuli. The endocrine system controls slower, longer lasting responses to internal stimuli. The endocrine system controls slower, 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)  Come from Neurons  Endorphins  Various Sources  Hormones  Come from glands (the Endocrine System)

Review: Synapse What is a synapse? What is a synapse? A synapse is the “gap” between the axon of one nerve and the dendrite of the next one. A synapse is the “gap” between the axon of one nerve and the dendrite of the next one. NT’s travel through the Synapse NT’s travel through the Synapse

Review: Neurotransmitters Chemical messengers released from neurons into the synapse Chemical messengers released from neurons into the synapse There are dozens of different neurotransmitters (NT) in the neurons of the body. There are dozens of different neurotransmitters (NT) in the neurons of the body. NTs can be either excitatory or inhibitory NTs can be either excitatory or inhibitory

What happens to NTs after they give their signal? They may return to their starting vesicles in the axon button – “reuptake” They may return to their starting vesicles in the axon button – “reuptake” They may be absorbed and broken down by the body They may be absorbed and broken down by the body

Mnemonics for remembering our 4 NTs and 4 hormones NTs: SAND = Serotonin, Acetylcholine, Norepinephrine, Dopamine NTs: SAND = Serotonin, Acetylcholine, Norepinephrine, Dopamine Hormones: COME = Cortisol, Oxytocin, Melatonin, Epinephrine Hormones: COME = Cortisol, Oxytocin, Melatonin, Epinephrine

1. Serotonin Important in mood, sleep, aggression, impulsive behavior, movement, appetite, perception, attention and learning. Important in mood, sleep, aggression, impulsive behavior, movement, appetite, perception, attention and learning. In the spinal cord, serotonin is inhibitory in pain pathways. In the spinal cord, serotonin is inhibitory in pain pathways. Serotonin level is related to carbohydrate intake. Serotonin level is related to carbohydrate intake. Undersupply linked to depression; Prozac raises serotonin levels Undersupply linked to depression; Prozac raises serotonin levels

2. Acetylcholine (ACh) Controls motion; plays a role in attention & memory. Controls motion; plays a role in attention & memory. Usually excitatory. Usually excitatory. Anything that interferes with acetylcholine will produce paralysis. Anything that interferes with acetylcholine will produce paralysis. Alzheimer’s Disease results from degeneration of the cells that produce acetylcholine. Alzheimer’s Disease results from degeneration of the cells that produce acetylcholine.

3. Norepinephrine (noradrenaline) Important in wakefulness, learning, and mood. Important in wakefulness, learning, and mood. Can be excitatory or inhibitory. Can be excitatory or inhibitory. Released during stress reactions (fight or flight; sympathetic nervous system) Released during stress reactions (fight or flight; sympathetic nervous system) Imbalance associated with depression. Imbalance associated with depression.

4. Dopamine Important in movement, attention, learning and the regulation of emotional response. Important in movement, attention, learning and the regulation of emotional response. Necessary for the experience of reward/pleasure. Necessary for the experience of reward/pleasure. Usually inhibitory Usually inhibitory Excess associated with schizophrenia; decrease associated with Parkinson’s Disease. Excess associated with schizophrenia; decrease associated with Parkinson’s Disease.

Neural Communication Serotonin Pathways Dopamine pathways

Endorphins Another chemical messenger Another chemical messenger Naturally occurring substances that act like morphine in the body. Naturally occurring substances that act like morphine in the body. Reduce pain and increase pleasure. Reduce pain and increase pleasure. Some endorphins act as NTs, some act on NTs Some endorphins act as NTs, some act on NTs

The Endocrine System (hormones)  Endocrine System  the body’s “slow” chemical communication system  a set of glands that secrete hormones into the bloodstream

Hormones Hormones act through the bloodstream, instead of being released by neurons Hormones act through the bloodstream, instead of being released by neurons Hormones are slower but longer lasting than NTs Hormones are slower but longer lasting than NTs

Key Hormones HormoneGlandsFunction CortisolAdrenals Stress; Memory OxytocinPituitaryAttachment MelatoninPineal Regulates sleep Epinephrine (Adrenaline) Adrenals Fight or flight; emotion; stress

A spider’s venom causes paralysis. The venom probably affects: A. Serotonin B. Endorphins C. Norepinephrine D. Acetylcholine

Prozac increases the availability of serotonin in the brain. Prozac is a(n): A. Agonist A. Agonist B. Antagonist B. Antagonist C. Neurotransmitter C. Neurotransmitter