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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 • 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 • Deterioration of memory, reasoning and language skills • Symptoms may be due to loss of ACh neurons
Serotonin • Involved in sleep • Involved in depression • Prozac works by keeping serotonin in the synapse longer, giving it more time to exert an effect
Norepinephrine • Arousal • “Fight or flight” response
Dopamine • Involved in movement, attention and learning • Dopamine imbalance also involved in schizophrenia • Loss of dopamine- producing neurons is cause of Parkinson’s Disease
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
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
Endorphins • Control pain and pleasure • Released in response to pain • Morphine and codeine work on endorphin receptors Involved in healing effects of acupuncture
Endorphins • Runner’s high - feeling of pleasure after a long run is due to heavy endorphin release
Gamma-Aminobutyric Acid (GABA) • Main inhibitory neurotransmitter • Benzodiazepines (which include tranquilizers such as Valium) and alcohol work on GABA receptor complexes
Huntington’s Disease • Involves loss of neurons in striatum that utilize GABA • Symptoms: • jerky involuntary movements • mental deterioration
Glutamate • Major excitatory neurotransmitter • Too much glutamate (and too little GABA) associated with epileptic seizures
Hormonal communication Endocrine cells Blood- stream Target cells Hormones • Chemical messengers secreted into bloodstream
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
Hormones • Released by organs, including the stomach, intestines, kidneys and the brain • Also released by a set of glands called the endocrine system
Endocrine System • Consists of hormone-releasing glands • Includes: • hypothalamus • pituitary gland • adrenal glands • thyroid gland • parathyroid glands • pineal gland • pancreas • ovaries and testes
Hypothalamus and Hormones • Hypothalamus releases hormones or releasing factors which in turn cause pituitary gland to release its hormones
Pituitary Gland • “Master endocrine gland” • Produces hormones that control hormone production in other endocrine glands
Pituitary Gland • Also produces growth hormones • Too little pituitary activity produces dwarfism • Too much leads to gigantism
Pituitary Gland • Also involved in breastfeeding • Produces prolactin • stimulates milk production • Produces oxytocin • involved in milk release
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)
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