The Endocrine System Activity Controlling Mechanisms Nervous System Functions by sending electrical messages Action potential travels along a chain of neurons Very rapid response to stress and stimulus Short lived response Glands Exocrine Endocrine Pancreas both kinds Neuroendocrine Link Integrates the endocrine system and the nervous system Hypothalamus example o Can stimulate the hormones in the pituitary gland Chemical Messengers Hormones Endocrine System Functions through chemical signaling molecules chemical messages or secretions Hormones have the ability to affect every cell in the body don t usually Change the metabolic how it acts inside the cell activity of the cell There is a lag time between hormone secretion and a response Long effect time with ducts secretion located in duct sweat glands saliva secretion from gull bladder secrete hormones ductless secrete onto surface but mostly in bloodstream and go to multiple parts of the body secreted into the extracellular fluid Long distance chemical messengers produced in one part has an effect somewhere else effect is called target tissue due to the receptor for that hormone release in bloodstream to travel from one to the other organ Autocrines Chemicals that are produced by one part Paracrines Pheromones of the body that affect the cells that produce it proximal will alter the activity that was released by that same cell Chemicals that are produced by certain cells that only affect neighboring cells don t affect themselves Chemicals that are produced by one individual that affect another individual usually for mate attraction for humans release them in reproduction perspiration Hormone Classifications Amino acid based non steroid based o Majority of hormones are all hormones except produced by adrenal cortex and the gonads o Use secondary messengers o Water soluble o Cannot diffuse across a plasma membrane passively o Receptors are found on the outside of cell Steroid based o Consists of hormones of the gonads and the adrenal cortex o Fat soluble o Can diffuse across a plasma membrane o Receptors are found on the inside of cell o Biologically active lipid o More of a paracrine than a true hormone o leukotrienes and prostaglandins are the two most common in the Eicosanoid body Hormone Action Target cells are cells that possess a spefic receptor for a specific hormone Possible Hormone Actions o Open or close ion channels changes membrane potential and cell activity secrete o stimulates protein synthesis promotes production of new proteins o activates and deactives enzymes o promote secretion one hormone causes the other hormone to o stimulate mitosis increases number of target cells in body Hormonal Mechanisms Type of Hormone Amino acid based Steroid based Location of Receptor Outside Inside Direct or Indirect Activation Indirect Direct Action of a Steroid Hormone Goal produce new proteins 1 Endocrine gland is activated and hormone is released into fluid surrounding cells 2 Transported through body and reaches the target cell 3 Hormone diffuses through plasma membrane 4 Looks for receptor inside cell 5 Goes to receptor protein on DNA 6 Transcription takes place 7 mRNA translates on the ribosome leaves nucleus 8 Proteins produced particular hormone produces the same protein Actions of a Non Steroid Hormone Requires a secondary messenger Can either activate or deactivate proteins already present in the cell cAMP Mechanism 1 hormone released 1 2 3 4 5 6 7 receptor hormone bind RCH bind to G protein G protein activates adenylyl cylase Adenylyl cylase makes cAMP cAMP activates protein kinase PK phosphorylate proteins cAMP activates phosphodiesterase PIP2 Mechanism 1 2 3 4 5 6 7 Hormone binds to receptor hormone receptor complex activates G protein G protein activates phospholipase phospholipase splits PIP2 IP3 release of Ca from ER DAG activates protein kinase phosphorylates proteins Factors Affecting Hormone Action 1 hormone level in the bloodstream a The greater the amount of hormone the greater the effect 2 Number of receptors in on target cells a The greater number of receptors the greater the activity 3 Receptor affinity a The higher the affinity the higher the affect b All receptors have a high degree of specificity Up regulation When prolonged exposure causes an increase in the receptors which causes an increase in hormone activity Down regulation When prolonged exposure causes a decrease in the receptors which causes a decrease in hormone activity Description Example One hormone requires presence of second hormone to exert its full effects One helps the other More than one produced the same affect when both are present it causes a greater effect by having both More than one hormone has the opposite effect of that of another hormone Thyroid and gonad hormones work together to develop the structures of the reproductive hormones Epinephrine and glucagon deal with blood glucose regulation Glucagon and insulin Description Concentration of things inside the fluid blood levels can turn on or off the hormones ions and nutrients changing hormones react Direct neural stimulation to an endocrine gland can stimulate secretion Stimulate from an electoral impulse One hormone produced by one gland causes another hormone to be produced Modes of Endocrine Gland Stimulation Mechanism Humoral These mechanisms can all act all together or seperate Modified by the nervous system Inhibited by negative feedback Hormone Interactions Kind of Interaction Permissiveness Synergism Antagonism Neural Hormonal Endocrine Glands 1 2 3 4 5 6 Pituitary Thyroid Parathyroids Adrenals Pancreas Gonads 7 8 Pineal Thymus Pituitary Gland Hypophysis Divided into two equal parts Connected to the hypothalamus by the infundibulum Posterior pituitary neurohypophysis Outgrowth of the hypothalamus Derived from neural tissue Does not produce any actual Releases stored hormones from the hormones hypothalamus Neurohypophyseal Hormones Hormone Oxytocin Anterior pituitary adenohypophysis Out pocket of the oral cavity Made of glandular tissue Not only stores but produces hormones because has glands Description Stimulates smooth muscle contractions child birth milk ejection Sexual arousal and satisfaction Stimulates nurturing and affectionate behavior cuddle hormone Antidiuretic hormone ADH An amnesiac memory forgetfulness Functions through positive feedback Regulates water balance Prevents urine formation Important for kidney function Adenohypophyseal Hormones Hormone Growth