EXSS 276 1st EditionExam # 2 Study Guide Lectures: 9 - 15Endocrine System-Hypothalamus and PituitaryExocrine- Secrete products into ducts, ducts carry secretions to target site- Sweat, oil, mucous, digestive glands- Exo = outsideEndocrine: secrete products into interstitial fluid of secretory cells, then diffuses into capillaries (carried away by blood)- Pituitary, thyroid, adrenal, pineal glands- Endo = w/inHormones- Involve secretion from glands (no ducts)- Endocrine glands secrete products (hormones) into interstitial fluid of secretory cells, then diffuse into capillaries (carried away by blood) - Released in one part of the body, but regulate the activity of cells in other parts of the body- High degree of specificityo Specific hormones act on specific target cells which have specific receptors - Highly regulated- Elicit specific physiological responses- Powerful effects in low concentrations- Bring about change by:o Altering biochemical pathwayso Turning enzymes on/offo Promoting protein synthesis at target tissueGeneral Mechanisms- Hormone binds to receptor on cell target- Cell may either o Synthesize new moleculeso Change permeability of membraneo Alter rates of reactions- Each target cell responds to hormone differently ClassificationLocationCirculating- Endocrine hormones travel in blood, act on distant target cellsLocal- Paracrine: travel in extracellular space (not in blood), act on neighboring cells- Autocrine: travel in extracellular space (not in blood), act on same cell that secreted itChemical StructureLipid-Soluble- Bind to transport proteins to be carried in bloodo Steroids, thyroid hormones, nitric oxide- Direct Gene Activationo Lipid-soluble hormones bind to and activate receptors w/in cellso Activated receptors alter gene expression which results in formation of new proteinso New proteins alter cells activity and result in physiological responses of those hormonesWater-soluble- Circulate freely in plasma (no transporter required)o Amines; peptides, proteins, glycoproteins; eicosanoids- Second Messenger Activationo Water-soluble hormones activate plasma membrane receptorso Set off a cascade of events inside the cello 1st messenger: the hormone that binds to the cell membrane receptoro 2nd messenger: released inside the cell where hormone-stimulated response takes place Amplification of Hormone Effects- Single molecule of hormone binds to receptor- Activates ~100 G-proteins- Each G-protein activates an adenylate cyclase, produces ~1000 cAMP- Each cAMP activates protein kinase which may act on ~1000+ substrate moleculesRegulation of Hormone Levels- Stimuli provoking endocrine gland to start production-secretion process- Humoral: some sort of chemical change in blood/body fluido Ex: increased glucose causes release of insulin- Neural: signal from nervous systemo Preganglionic sympathetic nerve fiber stimulates adrenal medulla to secrete catecholamines- Hormonal: involves a hormoneo Pituitary gland secretes thyroid stimulating hormone that causes thyroid gland torelease T3 and T4- Amount of each hormone in blood varies - Constant change in amount/type of stimuli- Regulated by feedback loopsHypothalamus and Pituitary Gland- Hypothalamus = major integrating link between nervous and endocrine systems- Receives input from cortex, thalamus, limbic system, and internal organs- Controls pituitary gland w/ 9 releasing and inhibiting hormones- Hypothalamus and pituitary gland regulate virtually all aspects of growth development, metabolism, homeostasisHypothalamic Releasing Hormones- Releasing hormones control release of hormones from anterior pituitary- Releasing hormones made in hypothalamus- Releasing hormones released in hypophyseal portal system, travel to anterior pituitaryHypothalamus Pituitary Hormone FunctionThyroid Hormone ReleasingHormone (TRH)Thyrotropin (TSH) Stimulate Thyroid Gland, Stimulate TH productionGrowth Hormone ReleasingHormone (GHRH)Growth Hormone (hGH)*Organ/tissue targetStimulate protein synthesisin tissues, maturation, bone growth, increase glucose and lipolysisCorticotropin Releasing Hormone (CRH)Adrenocorticotropin (ACTH) Stimulate Adrenal Cortex, simulate cortisol productionGonadotropin Releasing Hormone (GnRH)Follicle Stimulating (FSH) Stimulate gonads“” Luteinizing Hormone (LH) Stimulate gonads Prolacting Inhibiting Hormone (PIH)Prolactin*Organ/tissue targetMammary glandStored and released in posterior pituitary but made in hypothalamusOxytocin*Organ/tissue targetLabor contractions and lactationVasopressin (ADH)*Organ/tissue targetVasoconstrictor and renal water absorption The Endocrine SystemStress Hormones- Hormones of the adrenal glandsAdrenal Glands- Outer cortex (3 hormones released)o 1. Cortisol Most abundant of glucocorticoidso Secreted by adrenal cortex under control of hypothalamic-pituitary axiso Stimuli for release: Emotional stress Physical stress and trauma Exercise  Decreased blood glucose levelso Physiological responses Metabolic: breakdown of protein to amino acids, hepatic gluconeogenesis, lipolysiso Cardiovascular effects Increased blood vessel sensitivity to hormone induced vasoconstrictiono Immune system effects Inhibits WBC that participate in inflammatory responses (anti-inflammatory) Depresses other immune system responses o Regulation Hypothalamus (CRH) => pituitary (ACTH) => adrenal cortex => cortisolo Cushing’s Syndrome Hormonal disorder caused by prolonged exposure of body tisues to high levels of cortisol Affects 20-50 yr 10-15 out of every million people affected  Symptoms- Upper body obesity- Thing fragile skin and fragile bones- Weakness, fatigue, irritation, high blood glucose and high BP Treatments- Taper doses of glucocorticoids- Removal tumors- Drugs to inhibit cortisol synthesiso Addison’s Disease Adrenal insufficiency Low blood glucose, low BP, fatigue, weakness, loss appetite, weight loss- Inner medullao Produces catecholamines o Epinephrine (80%)o Norepinephrine (20%)o Metabolic effects: Substrate use and mobilization Glycogen breakdown Lipolysiso Cardiovascular effects: Increase heart rate, force of contraction, BP, blood flow Dilation of airwayso Stimulation for release of catecholamines Increases in SNS activity Decreases in blood glucose Increase in emotional stress Exerciseo Stress General Adaptation