Chemical Messengers Neurotransmitters Hormones Neurohormones

Types of Neurotransmitters Acetylcholine Serotonin Norepinephrine Dopamine Endorphins GABA Glutamate The slides following this can be viewed sequentially or by using the branching icons on each slide to go forward from this index slide and come back to it. This permits the instructor to select which subsets of slides to present.

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

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

Adrenal Glands Involved in stress response Hormones released include: 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. 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