Hormones and Behavior Lecture PDF

Hormones and Behavior The discovery of hormones complements the discovery of neurotransmitters. Arnold Adolph Berthold ‘s 1849 experiment Forms of chemical neurotransmission Synaptic communication: release of a neurotransmitter Endocrine communication: release of a hormone Autocrine...

Hormones and Behavior The discovery of hormones complements the discovery of neurotransmitters. Arnold Adolph Berthold ‘s 1849 experiment Forms of chemical neurotransmission Synaptic communication: release of a neurotransmitter Endocrine communication: release of a hormone Autocrine communication: self-referential Paracrine communication: proximal Pheromone communication: between individuals Chemical neurotransmission Hormones Neurotransmitters Travel through the Travel across the synapse bloodstream Fast acting, short duration Slow acting, long duration Function: send neural Function: alter ongoing signals to other neurons, physiological processes muscles or gland General principles of hormonal actions 1. Gradual 2. Modulatory 3. Reciprocity 4. Variety 5. Secretion 6. Rhythmic variation 7. Interaction 8. Receptor binding The neuroendocrine system Sensory reception Cortical processing Hormone release Like neurotransmitters, hormones are classified chemical structure  The experience of stress causes a cascade of hormone signaling called thehypothamalic- pituitary-adrenal (HPA) axis The release of cortisol acts as a negative feedback loop Inhibiting the activity of the hypothalamus and pituitary gland Dysregulation of the negative feedback loop: Cushing’s disease Anxiety disorders The hypothalamus: the “brains” of the endocrine system Let’s get glandular! 1. Pituitary gland Lobes of the pituitary gland Anterior pituitary gland (adenohypophysis): Secretes releasing hormones Posterior pituitary gland (neurohypophysis): Secretes oxytocin and vasopressin (anti-diuretic hormone)  Posterior pituitary pathway Direct pathway Axons of hypothalamic neurons release oxytocin and vasopressin into the bloodstream Example: oxytocin  Anterior pituitary pathway Indirect pathway Hypothalamic nuclei produce releasing factors, which are secreted into the hypophyseal artery The anterior pituitary responds to releasing factors by modulating the secretion of other hormones (i.e. tropic hormones) Let’s get glandular! 1. Pituitary gland 2. Thyroid gland  Thyroid hormones: Thyroxine Triiodothyronine Pathway: Hypothalamus releases thyrotropin-releasing hormone (TRH) Anterior pituitary gland releases thyroid stimulating hormone (TSH) Let’s get glandular! 1. Pituitary gland 2. Thyroid gland 3. Adrenal gland  The adrenal complex 1. Adrenal cortex (outer): layers of cells that produce steroid hormones 2. Adrenal medulla (inner): innervated by autonomic nerves Let’s get glandular! 1. Pituitary gland 2. Thyroid gland 3. Adrenal gland 4. Pineal gland