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Chemical Messengers

Chemical Messengers. Neurotransmitters Hormones Neurohormones. Types of Neurotransmitters. Acetylcholine Serotonin Norepinephrine Dopamine Endorphins GABA Glutamate. Acetylcholine. Found in neuromuscular junction Involved in muscle movements. Alzheimer’s Disease.

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Chemical Messengers

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  1. Chemical Messengers • Neurotransmitters • Hormones • Neurohormones

  2. Types of Neurotransmitters • Acetylcholine • Serotonin • Norepinephrine • Dopamine • Endorphins • GABA • Glutamate

  3. Acetylcholine • Found in neuromuscular junction • Involved in muscle movements

  4. Alzheimer’s Disease • Deterioration of memory, reasoning and language skills • Symptoms may be due to loss of ACh neurons

  5. Serotonin • Involved in sleep • Involved in depression • Prozac works by keeping serotonin in the synapse longer, giving it more time to exert an effect

  6. Norepinephrine • Arousal • “Fight or flight” response

  7. Dopamine • Involved in movement, attention and learning • Dopamine imbalance also involved in schizophrenia • Loss of dopamine- producing neurons is cause of Parkinson’s Disease

  8. Parkinson’s Disease • Results from loss of dopamine-producing neurons in the substantia nigra • Symptoms include: • difficulty starting and stopping voluntary movements • tremors at rest • stooped posture • rigidity • poor balance

  9. Parkinson’s Disease • Treatments: • L-dopa • transplants of fetal dopamine-producing substantia nigra cells • adrenal gland transplants • electrical stimulation of the thalamus to stop tremors

  10. Endorphins • Control pain and pleasure • Released in response to pain • Morphine and codeine work on endorphin receptors Involved in healing effects of acupuncture

  11. Endorphins • Runner’s high - feeling of pleasure after a long run is due to heavy endorphin release

  12. Gamma-Aminobutyric Acid (GABA) • Main inhibitory neurotransmitter • Benzodiazepines (which include tranquilizers such as Valium) and alcohol work on GABA receptor complexes

  13. Huntington’s Disease • Involves loss of neurons in striatum that utilize GABA • Symptoms: • jerky involuntary movements • mental deterioration

  14. Glutamate • Major excitatory neurotransmitter • Too much glutamate (and too little GABA) associated with epileptic seizures

  15. Hormonal communication Endocrine cells Blood- stream Target cells Hormones • Chemical messengers secreted into bloodstream

  16. Hormones vs. Neurotransmitters • Distance traveled between release and target sites • hormones travel longer distances • neurotransmitters - travel across a synaptic cleft (20 nm) • Speed of communication • hormones - slower communication • neurotransmitters - rapid, specific action

  17. Hormones • Released by organs, including the stomach, intestines, kidneys and the brain • Also released by a set of glands called the endocrine system

  18. Endocrine System • Consists of hormone-releasing glands • Includes: • hypothalamus • pituitary gland • adrenal glands • thyroid gland • parathyroid glands • pineal gland • pancreas • ovaries and testes

  19. Hypothalamus and Hormones • Hypothalamus releases hormones or releasing factors which in turn cause pituitary gland to release its hormones

  20. Pituitary Gland • “Master endocrine gland” • Produces hormones that control hormone production in other endocrine glands

  21. Pituitary Gland • Also produces growth hormones • Too little pituitary activity produces dwarfism • Too much leads to gigantism

  22. Pituitary Gland • Also involved in breastfeeding • Produces prolactin • stimulates milk production • Produces oxytocin • involved in milk release

  23. Shadowy figure Brain interprets stimulus as fearsome. Hypothalamus secretes corticotropin-releasing factor into blood portal path to anterior pituitary. Anterior pituitary secretes corticotropin, carried by blood to the adrenal gland. Adrenal secretes cortisol and other hormones. The adrenal hormones act on various tissues to enable adaptation to stress. Adrenal Glands • Involved in stress response • Hormones released include: • epinephrine (a.k.a. adrenaline) • norepinephrine (a.k.a. noradrenaline)

  24. Endocrine Glands • Thyroid gland - metabolism • Pineal gland - sleep and wakefulness • Pancreas - regulates blood sugar level • Ovaries and testes - secrete sex hormones such as testosterone and estrogen

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