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Trouble brewing? Trouble brewing? 2 choices… Trouble brewing? 2 choices… OR Two systems coordinate communication throughout the body: the endocrine system and the nervous system • The endocrine system secretes hormones that coordinate slower but longer-acting responses including reproduction, development, energy metabolism, growth, and behavior • The nervous system conveys high-speed electrical signals along specialized cells called neurons; these signals regulate other cells © 2011 Pearson Education, Inc. LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Chapter 45 Hormones and the Endocrine System Lectures by Erin Barley Kathleen Fitzpatrick © 2011 Pearson Education, Inc. Andre the Giant had acromegaly: HGH secreted in adulthood To what would hyposecretion of HGH in childhood lead? Glands of the endocrine system Let’s review stuff we know… What’s the difference? • Endocrine • Paracrine • Autocrine Methods of intercellular communication by secreted molecules Blood vessel Response (a) Endocrine signaling Response (b) Paracrine signaling – short distances Response (c) Autocrine signaling – short distances Synapse Neuron Response (d) Synaptic signaling Neurosecretory cell Blood vessel (e) Neuroendocrine signaling Response What’s the difference? • Endocrine • Exocrine How do they work differently? • Protein • Steroid Synaptic and Neuroendocrine Signaling • In synaptic signaling, neurons form specialized junctions with target cells, called synapses • At synapses, neurons secrete molecules called neurotransmitters that diffuse short distances and bind to receptors on target cells • In neuroendocrine signaling, specialized neurosecretory cells secrete molecules called neurohormones that travel to target cells via the bloodstream © 2011 Pearson Education, Inc. Signaling by Pheromones, hormones outside the self • Pheromones serve many functions, including: marking trails leading to food, defining territories, warning of predators, and attracting potential mates © 2011 Pearson Education, Inc. Figure 45.4 Major endocrine glands: Hypothalamus Pineal gland Pituitary gland Thyroid gland Parathyroid glands (behind thyroid) Organs containing endocrine cells: Thymus Heart Liver Adrenal glands (atop kidneys) Stomach Pancreas Kidneys Ovaries (female) Small intestine Testes (male) 3 Chemical classes of hormones ( or two ) Water-soluble (hydrophilic) Lipid-soluble (hydrophobic) Polypeptides Steroids 0.8 nm Insulin Cortisol Amines Epinephrine Thyroxine Example Pathway A simple endocrine pathway Negative feedback Low pH in duodenum Stimulus Endocrine cell S cells of duodenum secrete the hormone secretin ( ). Hormone Target cells Response Blood vessel Pancreas Bicarbonate release Example Pathway A simple neuroendocrine pathway Stimulus Suckling Sensory neuron Positive feedback Hypothalamus/ posterior pituitary Neurosecretory cell Posterior pituitary secretes the neurohormone Neurohormone oxytocin ( ). Blood vessel Target cells Response Smooth muscle in breasts Milk release SECRETORY CELL Lipidsoluble hormone Watersoluble hormone Receptor location varies with hormone type. VIA BLOOD Signal receptor Transport protein TARGET CELL Signal receptor NUCLEUS (a) (b) Figure 45.6-2 SECRETORY CELL Lipidsoluble hormone Watersoluble hormone VIA BLOOD Signal receptor TARGET CELL Cytoplasmic response Transport protein OR Gene regulation Signal receptor Cytoplasmic response NUCLEUS (a) (b) Gene regulation Animation: Water-Soluble Hormone Right-click slide / select”Play” © 2011 Pearson Education, Inc. Figure 45.7-1 Epinephrine (aka) adrenaline, has multiple effects Epinephrine Adenylyl cyclase G protein G protein-coupled receptor GTP ATP cAMP Second messenger Figure 45.7-2 Epinephrine Adenylyl cyclase G protein G protein-coupled receptor GTP ATP cAMP Inhibition of glycogen synthesis Promotion of glycogen breakdown Protein kinase A Second messenger Animation: Lipid-Soluble Hormone Right-click slide / select”Play” © 2011 Pearson Education, Inc. Hormone (estradiol) Steroid hormone receptors directly regulate gene expression Estradiol (estrogen) receptor EXTRACELLULAR FLUID Plasma membrane Hormone-receptor complex Figure 45.8-2 EXTRACELLULAR FLUID Hormone (estradiol) Estradiol (estrogen) receptor Plasma membrane Hormone-receptor complex NUCLEUS CYTOPLASM DNA Vitellogenin mRNA for vitellogenin Multiple Effects of Hormones • The same hormone may have different effects on target cells that have for two reasons: © 2011 Pearson Education, Inc. Multiple Effects of Hormones • The same hormone may have different effects on target cells that have for two reasons: 1. Different receptors for the hormone 2. Different signal transduction pathways © 2011 Pearson Education, Inc. One hormone, different effects Same receptors but different Different receptors intracellular proteins (not shown) Different cellular responses Different cellular responses Epinephrine Epinephrine Epinephrine receptor receptor receptor Glycogen deposits Glycogen breaks down and glucose is released from cell. (a) Liver cell Vessel dilates. (b) Skeletal muscle blood vessel Vessel constricts. (c) Intestinal blood vessel Multiple Effects of Hormones • The same hormone may have different effects on target cells that have for two reasons: 1. Different receptors for the hormone 2. Different signal transduction pathways Also…… 3. Perception of physical response e.g. “Love on a bridge study” © 2011 Pearson Education, Inc. What functions hormones control… Figure 45.1What signals caused this butterfly to grow within the body of a caterpillar? Brain Neurosecretory cells Regulation of insect development and metamorphosis Corpora cardiaca Corpora allata PTTH Prothoracic gland Juvenile hormone (JH) Ecdysteroid EARLY LARVA Brain Regulation of insect development requires multiple hormones Neurosecretory cells Corpora cardiaca Corpora allata PTTH Prothoracic gland Juvenile hormone (JH) Ecdysteroid EARLY LARVA LATER LARVA Figure 45.10-3 Brain Neurosecretory cells Corpora cardiaca Corpora allata PTTH Prothoracic gland Juvenile hormone (JH) Low JH Ecdysteroid EARLY LARVA LATER LARVA PUPA ADULT Maintenance of glucose homeostasis is done by paired hormones, insulin and glucagon Insulin Beta cells of pancreas release insulin into the blood. STIMULUS: Blood glucose level rises (for instance, after eating a carbohydrate-rich meal). Homeostasis: Blood glucose level (70–110 mg/100 mL) Figure 45.13a-2 Insulin Body cells take up more glucose. Blood glucose level declines. Beta cells of pancreas release insulin into the blood. Liver takes up glucose and stores it as glycogen. STIMULUS: Blood glucose level rises (for instance, after eating a carbohydrate-rich meal). Homeostasis: Blood glucose level (70–110 mg/100 mL) Figure 45.13b-1 Homeostasis: Blood glucose level (70–110 mg/100 mL) STIMULUS: Blood glucose level falls (for instance, after skipping a meal). Alpha cells of pancreas release glucagon into the blood. Glucagon Figure 45.13b-2 Homeostasis: Blood glucose level (70–110 mg/100 mL) STIMULUS: Blood glucose level falls (for instance, after skipping a meal). Blood glucose level rises. Liver breaks down glycogen and releases glucose into the blood. Alpha cells of pancreas release glucagon into the blood. Glucagon Diabetes Mellitus • Diabetes mellitus is perhaps the best-known endocrine disorder • It is caused by a deficiency of insulin or a decreased response to insulin in target tissues • It is marked by elevated blood glucose levels © 2011 Pearson Education, Inc. • Type 1 diabetes mellitus (insulin-dependent) is an autoimmune disorder in which the immune system destroys pancreatic beta cells • Type 2 diabetes mellitus (non-insulin-dependent) involves insulin deficiency or reduced response of target cells due to change in insulin receptors © 2011 Pearson Education, Inc. 45.3 Coordination of Endocrine and Nervous Systems in Vertebrates • The hypothalamus receives information from the nervous system and initiates responses through the endocrine system • Attached to the hypothalamus is the pituitary gland, composed of the posterior pituitary and anterior pituitary © 2011 Pearson Education, Inc. Figure 45.14 Cerebrum Pineal gland Thalamus Hypothalamus Cerebellum Pituitary gland Spinal cord • The posterior pituitary stores and secretes hormones that are made in the hypothalamus • The anterior pituitary makes and releases hormones under regulation of the hypothalamus Hypothalamus Posterior pituitary Anterior pituitary tropic hormones = target endocrine glands hypothalamus thyroid-stimulating hormone (TSH) Thyroid gland Adrenal cortex posterior antidiuretic pituitary hormone (ADH) anterior pituitary gonadotropic hormones: folliclestimulating hormone (FSH) & luteinizing hormone (LH) Kidney tubules Muscles of uterus Melanocyte in amphibian Bone and muscle Testes Ovaries Mammary glands in mammals Table 45.1a Table 45.1b Thyroid Regulation: A Hormone Cascade Pathway • A hormone can stimulate the release of a series of other hormones, the last of which activates a nonendocrine target cell; this is called a hormone cascade pathway • The release of thyroid hormone results from a hormone cascade pathway involving the hypothalamus, anterior pituitary, and thyroid gland • Hormone cascade pathways typically involve negative feedback © 2011 Pearson Education, Inc. Example Pathway Stimulus Cold Sensory neuron A hormone cascade pathway Hypothalamus Neurosecretory cell Hypothalamus secretes thyrotropin-releasing hormone (TRH ). Releasing hormone Blood vessel Negative feedback Anterior pituitary Tropic hormone Endocrine cell Anterior pituitary secretes thyroid-stimulating hormone (TSH, also known as thyrotropin ). Thyroid gland secretes thyroid hormone (T3 and T4 ). Hormone Target cells Response Body tissues Increased cellular metabolism Evolution of Hormone Function • Over the course of evolution the function of a given hormone may diverge between species – For example, thyroid hormone plays a role in metabolism across many lineages, but in frogs has taken on a unique function: stimulating the resorption of the tadpole tail during metamorphosis © 2011 Pearson Education, Inc. Hormones as homologous structures What does this tell you about these hormones? How could these hormones have different effects? same gene family gene duplication? prolactin mammals milk production birds fat metabolism fish amphibians salt & water balance metamorphosis & maturation growth hormone growth & development • Melanocyte-stimulating hormone (MSH) regulates skin color in amphibians, fish, and reptiles by controlling pigment distribution in melanocytes • In mammals, MSH plays additional roles in hunger and metabolism in addition to coloration © 2011 Pearson Education, Inc. The roles of parathyroid hormone (PTH) in regulating blood calcium levels in mammals. PTH Parathyroid gland (behind thyroid) STIMULUS: Falling blood Ca2 level Homeostasis: Blood Ca2 level (about 10 mg/100 mL) Figure 45.20-2 Increases Ca2 uptake in intestines Active vitamin D Stimulates Ca2 uptake in kidneys PTH Stimulates Ca2 release from bones Parathyroid gland (behind thyroid) STIMULUS: Falling blood Ca2 level Blood Ca2 level rises. Homeostasis: Blood Ca2 level (about 10 mg/100 mL) Multiple hormonal pathways/effects during “fight or flight” • Epinephrine and norepinephrine – Trigger the release of glucose and fatty acids into the blood – Increase oxygen delivery to body cells – Direct blood toward heart, brain, and skeletal muscles and away from skin, digestive system, and kidneys • The release of epinephrine and norepinephrine occurs in response to involuntary nerve signals © 2011 Pearson Education, Inc. Effects of stress on a body Stress Nerve Spinal cord signals (cross section) Hypothalamus Releasing hormone Nerve cell Anterior pituitary Blood vessel adrenal medulla secretes epinephrine & norepinephrine Nerve cell ACTH Adrenal gland Adrenal cortex secretes mineralocorticoids & glucocorticoids Kidney (A) SHORT-TERM STRESS RESPONSE Effects of epinephrine and norepinephrine: 1. Glycogen broken down to glucose; increased blood glucose 2. Increased blood pressure 3. Increased breathing rate 4. Increased metabolic rate 5. Change in blood flow patterns, leading to increased alertness & decreased digestive & kidney activity (B) LONG-TERM STRESS RESPONSE Effects of mineralocorticoids: Effects of glucocorticoids: 1. Retention of sodium ions & water by kidneys 1. Proteins & fats broken down & converted to glucose, leading to increased blood glucose 2. Increased blood volume & blood pressure 2. Immune system suppressed Figure 45.21 (b) Long-term stress response and the adrenal cortex (a) Short-term stress response and the adrenal medulla Stress Spinal cord (cross section) Hypothalamus Nerve signals Releasing hormone Nerve cell Anterior pituitary Blood vessel Adrenal medulla secretes epinephrine and norepinephrine. Nerve cell ACTH Adrenal cortex secretes mineralocorticoids and glucocorticoids. Adrenal gland Kidney Effects of epinephrine and norepinephrine: • Glycogen broken down to glucose; increased blood glucose • Increased blood pressure • Increased breathing rate • Increased metabolic rate • Change in blood flow patterns, leading to increased alertness and decreased digestive, excretory, and reproductive system activity Effects of mineralocorticoids: Effects of glucocorticoids: • Retention of sodium ions and water by kidneys • Proteins and fats broken down and converted to glucose, leading to increased blood glucose • Increased blood volume and blood pressure • Partial suppression of immune system • Glucocorticoids, such as cortisol, influence glucose metabolism and the immune system • Mineralocorticoids, such as aldosterone, affect salt and water balance • The adrenal cortex also produces small amounts of steroid hormones that function as sex hormones © 2011 Pearson Education, Inc. Sex Hormones • The gonads, testes and ovaries, produce most of the sex hormones: androgens, estrogens, and progestins • All three sex hormones are found in both males and females, but in significantly different proportions © 2011 Pearson Education, Inc. • The testes primarily synthesize androgens, mainly testosterone, which stimulate development and maintenance of the male reproductive system – Testosterone causes an increase in muscle and bone mass and is often taken as a supplement to cause muscle growth, which carries health risks – It has been suggested by some scientists that the ratio of two digits in particular, the 2nd (index finger) and 4th (ring finger), is affected by exposure to testosterone (androgens) in the uterus – Low 2D:4D is positively correlated with success in sport – Discovery article about ratio outcomes © 2011 Pearson Education, Inc. What role do hormones play in making a mammal male or female? RESULTS Appearance of Genitalia Chromosome Set No surgery Embryonic gonad removed XY (male) Male Female XX (female) Female Female Melatonin and Biorhythms • The pineal gland, located in the brain, secretes melatonin • Light/dark cycles control release of melatonin © 2011 Pearson Education, Inc. Did you know?… • One reason that kittens sleep so much is because a growth hormone is released only during sleep. • The levels of two stress hormones, cortisol and epinephrine which suppress the body's immune system, will actually drop after a dose of laughter. • Chocolate is associated with the release of serotonin, the hormone that makes you feel relaxed, calm, and happy. So are hugs.