MPP 3202 1st EditionExam # 2 Study Guide Chapters: 7 - 12Chapter 7: Endocrine SystemHormones:• Chemical messengers secreted into the blood by specialized cells• Cellular mechanism of action = when hormones bind to target cell receptors and initiate a biochemical response • Hormones control:◦ rate of enzymatic reactions ◦ transport of ions or molecules across the cell membrane ◦ gene expression◦ protein synthesis• Cell-to-cell communication:◦ chemical signals◦ secreted by a cell or group of cells◦ transported by blood◦ distant target tissue receptors◦ activates a physiological response at low concentrations• Pheromones = specialized ectohormones that act on other organisms of the same species to elicit physiological or behavioral response on other organisms of thesame species• Classification by chemical class◦ peptide or protein◦ steroid◦ amino acid-derived or amine• Peptides or Proteins◦ preprohormone = large, inactive precursor◦ prohormone = smaller, inactive, proteolytic, post-translational modification◦ peptide/protein = bind surface membrane receptors, cellular response through signal transduction system• Steroid◦ cholesterol-derived = lipophilic, easily cross membranes◦ bind carrier proteins in blood = longer half life◦ cytoplasmic or nuclear receptors = genomic effect to activate or repress genes for protein synthesis, slower acting◦ cell membrane receptors = nongenomic responses• Amino acid-derived or Amine◦ derived from:▪ tryptophan = pineal gland melatonin is derived from ▪ tyrosine = parent amino acid for catecholamines and TH◦ examples:▪ melatonin▪ thyroid hormones▪ catecholamines = bind to cell membrane receptors▪ epinephrine▪ norepinephrine▪ dopamine Comparison of peptide, steroid and amino-derived:• Synthesis and storage◦ peptide = made in advance, stored in secretory vesicles◦ steroid = synthesized on demand from precursors◦ catecholamines/thyroid = made in advance, stored in secretory vesicles • Release from parent cell◦ peptide = exocytosis◦ steroid = simple diffusion◦ catecholamines = exocytosis ◦ thyroid = simple diffusion• Transport in blood◦ peptide = dissolved in plasma◦ steroid = bound to carrier proteins◦ catecholamines = dissolved in plasma◦ thyroid = bound to carrier proteins• Location of receptor◦ peptide = cell membrane ◦ steroid = cytoplasm or nucleus◦ catecholamines = cell membrane◦ thyroid = nucleus • General target response◦ peptide = modification of existing proteins and induction of new protein synthesis◦ steroid = induction of new protein synthesis◦ catecholamines = modification of existing proteins◦ thyroid = induction of new protein synthesis• Examples◦ peptide = insulin, parathyroid hormone◦ steroid = estrogen, androgens, cortisol◦ catecholamines = epinephrine, norepinephrine◦ thyroid = thyroxineNeurohormones:• adrenal medulla◦ catecholamines • hypothalamus ◦ posterior pituitary is neural tissue◦ anterior pituitary is endocrine tissue The Pituitary Gland:• sits in a protective pocket of bone • Infundibulum = stalk that connects the gland to the brain• Posterior Pituitary◦ made and packaged in cell body of neuron◦ vesicles are transported down the cell ◦ vesicles containing neurohormone are stored in posterior pituitary◦ neurohormones are released into blood • Anterior Pituitary◦ Neurons synthesizing trophic neurohormones release them into capillaries of the portal system◦ Portal vessels carry the trophic neurohormones directly to the anterior pituitary, where they act on the endocrine cells◦ Endocrine cells release their peptide hormones into the second set of capillaries for distribution to the rest of the body◦ Prolactin = mammary glands◦ GH = musculoskeletal system◦ TSH = thyroid gland◦ ACTH = adrenal cortex◦ LH & FSH = gonadsEndocrine Control:• A trophic hormone controls the secretion of another hormone• Hypothalamic-hypophyseal portal system = specialized region of the circulation consisting of two sets of capillaries that are connected in a series, response acts as a negative feedback system • Three integrating centers - hypothalamic-pituitary pathways: ◦ Hypothalamic stimulation—from CNS◦ Anterior pituitary stimulation—from hypothalamic trophic hormones◦ Endocrine gland stimulation—from anterior pituitary trophic hormones (except prolactin)Hormone Interactions:• Synergism◦ Combined effect is greater than the sum of individual effects• Permissiveness ◦ Need second hormone to get full effect• Antagonism◦ One substance opposes the action of another◦ Competitive inhibitors vs. functional antagonism◦ Example: glucagons oppose insulinEndocrine Pathologies:• Hypersecretion = excess hormone◦ caused by tumors or exogenous (coming from outside of the body)iatrogenic (physician caused) treatment◦ negative feedback• Hyposecretion = deficient hormone◦ caused by decreased synthesized materials or atrophy◦ absence of negative feedbackPathologies: Abnormal Receptors:• Down-regulation ◦ decreased number of receptors◦ example: hyperinsulinemia • Receptor and signal transduction abnormalities◦ example: testicular feminization syndrome◦ example: pseudohypothyroidismChapter 8: NeuronsThe Nervous System:• Peripheral Nervous System (PNS)◦ Afferent division = sensory, to the CNS◦ Efferent division = from CNS to target cells▪ somatic motor = skeletal muscle ▪ autonomic▪ sympathetic and parasympathetic = control cardiac muscle, smooth muscle, exocrine glands, adipose tissue• Central Nervous System (CNS)Neuron Anatomy:• Cell body = contains nucleus• Dendrites = long processes that extend from the cell body, receive incoming information• Axon hillock = long process that carries outgoing information• Myelin sheath = oligodendrocytes in the CNS and Schwann cells in the PNS, used to insulate the axon and increases the speed of an action potential • Node of Ranvier = section of unmyelinated axon membrane between two Schwann cellsNeuron Types:• Pseudounipolar = single axon process◦ dorsal root ganglion cells• Bipolar = two equal fibers extending off the central cell body ◦ retinal cells, olfactory epithelium cells• Anaxonic = CNS interneurons that have no apparent axon◦ interneurons • Multipolar = CNS interneurons that are highly branched but lack long extensions◦ spinal motor neurons, pyramidal