Transcript ppt
Endocrine Glands Chemical Messengers •Autocrine •self signal •Paracrine •neighbor signal •Endocrine •distant signal •Pheromone •airborne signal •same species •Allomone •airborne signal •different species Hormone Types Homeostasis Mechanism Receptors input signals skin responds to cold temperature sends signal to brain Control Center integrating center brain interprets temp signal makes you shiver Effectors output mechanism muscles shiver creating heat Negative Feedback Results in an immediate reversal of the imbalanced system Immediately negates the disruption Most systems in the body work via negative feedback systems temperature glucose balance water balance blood pressure Positive Feedback Immediate further disruption of the imbalance so as to later return to homeostasis childbirth ovulation Positive Feedback: Childbirth Neuroendocrine Reflex Baby suckling stimulates receptors on the nipple Action potential travels to the hypothalamus Hypothalamus sends oxytocin to posterior pituitary gland Posterior pituitary releases oxytocin into the blood stream Oxytocin travels to the breast and triggers milk release Posterior Pituitary Hormones synthesized in the hypothalamus Released by the posterior pituitary •Oxytocin •milk ejection •orgasm •Vasopressin or ADH •water balance •blood pressure Anterior Pituitary Releasing hormones synthesized in the hypothalamus •CRF/CRH •GnRH •GHRH •TRH •PRH Triggers hormone release in anterior pituitary •ACTH •LH/FSH •GH •TSH •PRL The Stress Continuum Stress The process by which we perceive and respond to certain events, called stressors, that we appraise as threatening or challenging HPA Axis Hypothalamus •CRF/CRH Pituitary •ACTH Adrenals •Cortisol Stress and Hormone Release Stress Diathesis Model Existing Correlations: •Adult Depression : Elevated Cortisol levels •Childhood Abuse : Adult Depression Stress Diathesis Model: •Genetic Predisposition plus •Early Abuse/Neglect leads to •Adult Depression Animal Model shows: •More CRF neurons •Larger CRF neurons •More sensitive CRF neurons Early abuse permanently alters the stress response increasing the risk of depression General Adaptation Syndrome (GAS) 1. Alarm Reaction 2. Resistance Reaction 3. Exhaustion