Campbell and Reece Chapter 45

 body‘s long-distance regulators  molecules secreted into ECF  circulate thru body  communicate regulatory messages thru out body  in animals that undergo metamorphosis hormones stimulate growth of adult cells & apoptosis of larval cells

 with nervous system in charge of communication & regulation thru out body

Nervous SystemEndocrine System  rapid response  neurotransimitters  short distances  regulate neurons, muscle, glands, endocrine cells (area of overlap)  slower response  hormones  short or long distances  regulate functions of most organ systems

 signaling processes in animals:  classified by 2 criteria: 1. type of secreting cell 2. route signal takes to reach target

 hormones  ECF  bloodstream  target cells  functions: 1. maintain homeostasis 2. mediate responses to environmental stimuli 3. regulates growth & development

 molecules that act over short distances  reach target solely by diffusion ◦ ex: cytokines released by T helper cells  2 types: 1. paracrine 2. autocrine

 tion1501.html tion1501.html

 not all secreted molecules act w/in body  method of communication between members of some animal species ◦ ex: 1.foraging ant locates new food source  marks its path back to nest with pheromones 2.define boundaries of territory 3.attract mates: female giant silk moth releases pheromone that can attracgt a male up to 4.5 km away

 ductless organs  secrete hormones directly into surrounding fluid

1. Polypeptide 2. Steroid 3. Amines

Water-SolubleLipid-Soluble  secreted by exocytosis  travel thru blood  bind to cell-surface signal receptors  induces changes in cytoplasmic molecules  might alter gene transcription (signal transduction)  diffuse out of endocrine cell  bind to transport molecules in blood  diffuse into target cells  bind to intracellular receptors  trigger gene transcription

 effects hormone has can vary if target cells differ in molecules that receive or produce the response to the hormone

 pathways by which local regulators trigger responses same as those activated by hormones  growth factors ◦ stimulate cell proliferation & differentiation  NO (nitric oxide) ◦ synthesized & released by endothelial cell when O 2 levels low  activates enzyme in smooth muscle  vasodilation  increased blood flow  prostaglendins: ◦ aggregation of platelets  blood clotting ◦ promote fever & inflammation in immune system ◦ smooth muscle contraction

 occurs in all but simplest invertebrates

Negative FeedbackPositive Feedback  stimulus initiates a response that will reduce the effect of the stimulus  stimulus initiates a response that reinforces the stimulus

 Insulin lowers blood glucose levels by: ◦ stimulating nearly all cells *outside the brain to take up glucose ◦ slowing glycogen breakdown in liver ◦ inhibiting glycerol (from fats) & a.a.  glucose aka gluconeogenesis  *brain cells do not require insulin to take up glucose

 Glucagon influences blood glucose levels mainly thru it effects on target cells in liver  when serum glucose levels < normal (70 – 110 mg/100 mL) glucagon signals liver cells to release glucose  blood by: 1.increase glycogen hydrolysis 2.convert a.a. & glycerol  glucose

 deficiency of insulin in target tissues  hi blood glucose levels but cannot get into cells so cells use fat as main substrate for cellular respiration  acidic metabolites form during fat breakdown  ketoacidosis ◦ low pH can be life threatening ◦ Na+ & K+ ions depleted

 characterized by failure of target cells to take up insulin from blood  elevated blood glucose  7 th most common cause of death in USA  contributing factors: ◦ genetics (defect in insulin receptor or insulin response pathway) ◦ obesity ◦ age (though more children being diagnosed) ◦ sedentary lifestyle

 Hypothalamus ◦ plays central role in integrating endocrine & nervous systems ◦ receives info  initiates endocrine signaling appropriate to environmental conditions ◦ sends releasing hormones to anterior pituitary gland  sends tropic hormones to target glands ◦ sends hormones it makes to posterior pituitary

1. ADH: antidiuretic hormone (vasopressin) ◦ 1 of several hormones that act on kidneys ◦ increases water retention in kidneys (decreases urine vol/ increases blood plasma vol : maintains blood osmolarity wnl 2. Oxytocin ◦ increases strength on uterine contractions in labor ◦ regulates milk secretion by mammary glands

 over time functions of a hormone have diverged from species to species  ex: thyroxine (thyroid hormone) regulates metabolism in most animal but in frogs it function to resorb tadpole tail  Prolactin: in mammals develops mammary glands & milk production but in birds: regulates fat metabolism & reproduction; in amphibians: delays metamorphosis; in fish

 Animal Function  Mammalsdevelops mammary  ` glands & milk synthesis  Birds regulates fat metabolism  Amphibians delays metamorphosis  Fish regulates salt & water  ` balance 