BIOL 244 1st Edition Lecture 2Outline of Current Lecture I. Endocrine System vs. Nervous SystemII. Endocrine Organs III. Hormones IV. Hormone ActivityV. Target CellsVI. Control of Hormone ReleaseVII. Pituitary Gland and the HypothalamusCurrent LectureI. Endocrine System vs. Nervous Systema. Endocrine System is 2nd to the Nervous System in terms of control b. 3 main points of differentiation i. Type of message sent1. Nervous: Electrochemical 2. Endocrine: Chemical messages in form of hormonesii. Target cells1. Nervous: Muscles and glands2. Endocrine: Everythingiii. How long controls last1. Nervous: Quick response, effects very short lived2. Endocrine: Longer to respond, effects last longer II. Endocrine Organs a. Exocrine vs. Endocrinei. Exocrine1. Glands that produce non-hormonal secretions2. Typically have ductsii. Endocrine1. Produce hormones 2. Are ductlessb. Endocrine Glandsi. Pineal glandii. Pituitary glandiii. Thyroid glandThese 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.iv. Parathyroid glandv. Adrenal glandsc. Neuroendocrine organi. Hypothalamus: partially in the nervous system, partially in the endocrine systemd. Organs with endocrine tissue i. Have important functions in addition to hormonesii. Pancreasiii. Ovaryiv. Testisv. Placenta (temporary organ)e. Organs with scattered endocrine cellsi. Thymus ii. Includes nearly all of your organs III. Hormones a. Hormones vs. Autocrines and Paracrinesi. Autocrines: chemical messengers that have local effects on the cells that produce themii. Paracrines: Chemical messengers that have local effects on the cells in the area where they are producedb. Amino-acid based hormonesi. Variable in size (from 1 modified amino acidà groups of chains)ii. Built from amino acids/ are modified amino acidsc. Steroid hormonesi. Come from cholesterolii. Example: sex hormonesIV. Hormone Activitya. Hormones alter a cell’s normal activity b. Hormones only have effects on cells that have receptors for themc. In target cells:i. Change permeability or potential of plasma membrane1. Cause channels to open/closeii. Stimulate or inhibit the synthesis of proteinsiii. Influence enzyme activityiv. Induce secretory activity v. Stimulate mitosisd. Water-soluble hormones (all amino-acid based EXCEPT for thyroid hormone)i. Don’t influence cellular activity directly 1. Due to lipid bilayerii. Intracellular second messengersiii. G proteins 1. Regulatory proteinsiv. Example: Cyclic AMP signaling mechanismv. Example: PIP2-calcium signaling mechanisme. Lipid-soluble hormones (All steroid hormones and the thyroid hormone)i. Direct actionii. Binds to protein receptor INSIDE the cellV. Target Cells a. Hormone Effectiveness Variablesi. How much hormone is present at target cellii. How strongly hormone binds1. Binds longer = longer effectsiii. How many receptors are availableb. Have specific receptorsc. Changes in sensitivityi. Up-regulation 1. Enhances cell response to hormones 2. Increase in amount of hormone causes an increase in the amount of receptorsii. Down-regulation1. Removal/destruction of receptors for hormone2. Happens with a sustained large amount of hormone level3. Lowers sensitivity to hormone VI. Control of Hormone Releasea. Usually controlled by negative feedbackb. Humoral Controli. Levels of some substance in the blood stimulating releasec. Neural Controli. Nervous system stimulating release d. Hormonal Control i. One hormone leading to the release of another hormone VII. Pituitary Gland and the Hypothalamusa. Pituitary gland (hypophysis)i. 2 lobes: Only one is true endocrine gland (anterior)b. Posterior pituitaryi. Part of brainii. Doesn’t produce any of its own hormonesc. Anterior pituitaryi. Glandularii. Releases many hormones under the influence of hormones from the hypothalamus 1. Pro-opiomelanocortin (POMC)2. Tropins: Go towards other hormones and stimulate them to produce hormones a. Thyroid-stimulating hormone (TSH)i. Stimulates thyroid to produce hormonesii. Controlled by the thyrotropin releasing hormone (TRH)b. Adrenocorticotropic hormone (ACTH)i. CRH: corticotropin releasing hormone c. Gonadotropinsi. Follicle-stimulating hormone (FSH)ii. Leutenizing hormone (LH)3. Growth hormone (GH)a. Major Target organs: liver, bones, skeletal muscleb. IGFs: Insulin-like growth factors i. Can influence growth in other parts of the bodyii. Directly tells other organsc. GHRH: growth hormone releasing hormone i. Hypothalamic hormoned. GHIH: Growth hormone inhibiting hormone i. Hypothalamic hormone4. Prolactin