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

Receptorsinput signalsskin responds to cold temperaturesends signal to brain

Control Centerintegrating centerbrain interprets temp signalmakes you shiver

Effectorsoutput mechanismmuscles shiver creating heat

Negative Feedback

Results in an immediate reversalof the imbalanced system

Immediately negates thedisruption

Most systems in the body workvia negative feedback systems

temperatureglucose balancewater balanceblood pressure

Positive Feedback

Immediate further disruption of theimbalance so as to later return tohomeostasis

childbirthovulation

Positive Feedback: Childbirth

Neuroendocrine ReflexBaby 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 thehypothalamus

Released by the posterior pituitary

•Oxytocin•milk ejection•orgasm

•Vasopressin or ADH•water balance•blood pressure

Anterior Pituitary

Releasing hormones synthesizedin 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 ModelExisting 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 stressresponse increasing the risk of depression

General Adaptation Syndrome

1. Alarm Reaction2. Resistance Reaction3. Exhaustion

(GAS)