EXSS 276 1st Edition Lecture 9 Outline of Last Lecture I. Post-absorptive stateII. Absorptive stateIII. Diet and EnergyIV. Exam ReviewOutline of Current LectureI. Exocrine vs. Endocrine SystemII. HormonesIII. ClassificationIV. Amplification of Hormone EffectsCurrent LectureI. Exocrine vs. Endocrine Systema. Exocrine: secrete products into ducts, ducts carry secretions to target sitei. Sweat, oil, mucous, digestive glandsii. Exo: outsideb. Endocrine: secrete products (hormones) into interstitial fluid of secretory cells then diffuses into capillaries (carried away by blood)i. Pituitary, thyroid, adrenal, pineal glands, etc.ii. Endo: w/inII. Hormonesa. Involves secretion from glands (no ducts involved)i. Endocrine glands secrete products (hormones) into interstitial fluid of secretory cells, then diffuse into capillaries (carries away by blood)b. Endocrine system affects virtually all body tissuesi. Regulates:ii. Extracellular fluidiii. Metabolismiv. Biological Clockv. Contraction of cardiac and smooth musclevi. Some immune functionsvii. Growth and developmentviii. Reproduction c. Released I none part of body but regulate activity of cell in other partsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.d. High degree of specificityi. Specific hormones act on specific target cells, which have specific receptors for those hormonese. Highly regulated (by feedback loops)f. Elicit specific physiological responsesg. Powerful effects even in low concentrationsh. Bring about change by:i. Altering biochemical pathwaysii. Turning enzymes on/offiii. Promoting protein synthesis at target tissuei. General mechanism of hormone actioni. 1) Hormone binds to receptor on target cellii. 2) Cell may then1. Synthesize new molecules2. Change permeability of membrane3. Alter rate of reactionsiii. 3) Each target cell responds to hormone differentlyIII. Classificationa. Location of actioni. Circulating1. Endocrine hormones travel in blood, act on distant target cellsii. Local1. Paracrine: travel in extracellular space (not in blood); act on neighboring cells2. Autocrine: travel in extracellular space (not in blood); act on same cell that secreted itb. Chemical Structurei. Lipid-soluble: bind to transport proteins to be carried in the blood1. Lipids are hydrophobic2. Steroids, thyroid hormones, nitric oxide3. Direct gene activationa. Lipid-soluble hormones bind to and activate receptors w/incellsb. Activated receptors alter gene expression which results in formation of new proteinsc. New proteins alter cells activity and result in physiological responses of those hormonesd. Ex: steroid hormonesii. Water-soluble: circulate freely in plasma (no transporter required)1. Amines (serotonin, melatonin, epinephrine); peptides (anti-diuretic); proteins (insulin); glycoproteins (protein hormone w/ carbohydrate on it); eicosanoids 2. Second messenger activationa. Water-soluble hormones activate plasma membrane receptorsb. Set off cascade of events inside celli. First messenger: hormone that binds to cell membrane receptorii. Second messenger: released inside cell where hormone-stimulated response takes place1. Ex: Cyclic AMP (cAMP) a. Serves as second messenger to activate protein kinases c. Hormone can’t diffuse through plasma membraned. Receptors are integral membrane proteins3. Chemical structure affects how hormone acts on target cellsIV. Amplification of Hormone Effectsa. Single molecule of hormone bind to receptorb. Activates ~100 G-proteinsc. Each G-protein activates an adenylate cyclase, which then produces ~1000 cAMPd. Each cAMP activates protein kinase which may act on ~1000 + substrate moleculese. # Target cell expressing receptorsf. # Functional receptorsg. Affinity level of receptors for hormoneh. Post receptor amplification