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Chapter 45: Chemical Signals 1 Figure 45.0 A monarch butterfly just after emerging from its cocoon 1 2 Hormone • Chemical signal secreted into body fluids. • Regulation/control of homeostasis, development, growth • Specific response from specific cells—specificity • Release from gland, act on target cell Endocrine System (skip to slide 9) • Endocrine glands spread through the body. • Contain cells that secrete hormones directly to blood. • Contrast to Exocrine (secrete to epithelial surface). Feedback • Positive and Negative • Regulation of Calcium concentration—antagonistic hormones o muscle function, bone • Figures 1-2: Thyroid Hormone, Calcium control Figure 45.1 An example of how feedback regulation maintains homeostasis 2 3 Figure 45.2 Hormonal regulation of insect development (Layer 1) Figure 3 • Regulation of insect development • Exoskeleton—must shed/molt in order to grow/develop • Brain Hormone (BH)—from brain, stimulates prothoracic gland to secrete ecdysone 3 4 Figure 45.2 Hormonal regulation of insect development (Layer 2) 4 • Ecdysone triggers molting • Juvenile Hormone (JH) regulates development o Suppresses metamorphosisÆretain larval characteristics o High JHÆmolt but stay larval o Decreasing JHÆform pupa and become adult 5 Figure 45.2 Hormonal regulation of insect development (Layer 3) 5 6 Pupa Figure 45.x1 Pupa 6 7 Slide 7: Chemical Signaling Hormone Binds plasma membrane protein and initiates STP Signal Transduction Pathway • Reception (specific), signal transduction, response (Signal Transduction) • Amplification: small amt HM produces large response. Figure 45.3 Mechanisms of chemical signaling: a review Steroid Hormone Animation 7 Same signal can yield different response in different cells (Ach, Epi)— depends on receptor Steroids bind intracellular receptors • small non polar molecules Figure 4: • autocrine/paracrine--Immune System—histamine, GH • NT released by neurons--some HM can act as NT • Circulating HM Figure 5: Overproduction/underproduction of Growth HM Figure 6: Epinephrine pathway—Earl Sutherland Figure 7: Steroid Hormones (nonpolar)—from cholesterol 8 Acetylcholine Different effects on different cells Figure 45.4 One chemical signal, different effects 8 9 Can affect one or more tissues directly/indirectly Direct—have direct effect on tissue Tropic—target endo glands and cause to release hormone. Figure 45.5 Human endocrine glands surveyed in this chapter Adreno-cortico-tropic Hormone (ACTH) acts on Adrenal cortex cause release of Æglucocorticoids. *Some HM can be both direct and tropic (Growth HM) 9 1 0 Table 45.1 Major Vertebrate Endocrine Glands and Some of Their Hormones (Hypothalamus– Parathyroid glands) Overview of Hormones 10 1 1 Table 45.1 Major Vertebrate Endocrine Glands and Some of Their Hormones (Pancreas–Thymus) Overview of Hormones 11 1 2 Hypothalamus • Receives Info from body (nerves) • Secretions are stored in or regulate the Pituitary Gland 12 Posterior Pituitary (neurohypophysis) Extension of Brain, develops from Hypothalamus—connect by duct Stores/secretes ADH and Oxytocin Oxytocin • smooth muscle contraction o contract of uterus (during labor) give to induce labor o mammary gland during lactation o contract of smooth muscle in coitus ADH (vasopressin) 1 3 • • • Figure 45.6a Hormones of the hypothalamus and pituitary glands • regulate blood osmolarity water retention by kidney Increase osmolarityÆcells in HT shrink due to osmosisÆnerve signal to HTÆsecrete ADH from Posterior Pituitary. Decrease osmolarityÆslows release of ADH. 13 1 4 Figure 45.6b Hormones of the hypothalamus and pituitary glands 14 Anterior Pituitary (adenohypophysis) • From tissue above mouth • Connect to HT by blood vessel • synthesize and releases HM to blood • Responds to releasing or inhibiting hormones from HT • Tropic Hormones o TSH, ACTH, GH, FSH, LH (FSH and LH = Gonadotropins) Direct HM—GH, PRL, MSH (melanocyte stimulating HM), endorphins Growth Hormone (Figure 8) • Production of growth factors • Promote growth (bone and cartilage) o Direct Regulate deposition of collagen and chondroitin sulfate in bone and cartilage Promotes mitosis in osteoblasts Æ build bone o tropic—act on liver to stimulate insulin like growth factor (IGF) Æ growth Protein synthesis Decrease protein catabolism and use of aa for respiration Release of glucose from liver (antagonist to insulin) • Release after exercise or hours after meal to counteract decrease in blood glucose, mobilize fat for metabolism to increase glucose. • Problems if too much (gigantism) or not enough (dwarfism). o Growth plate: area of growing tissue near end of long bone. o Low levelÆ growth plates close before normal height (dwarf) o High level Æ gigantism • Can produce using bacteria Prolactin (PRL) • Different effects in different organisms o mammals: lactation o birds: fat metabolism, reproduction o amphibians: delay metamorphosis o fish: salt/water balance FSH and LH (Figure 13-14) • gonadotropins—tropic HM that act on gonads • stimulate gonads to release testosterone, estrogen TSH—stimulates thyroid to release TH (Figure 9) • Released in response to TSH releasing factor from HT ACTH- Adrenocorticotropic Hormone(Figure 10) • production/secretion of steroids by adrenal cortex MSH – Melanocyte Stimulating Hormone • Change in skin color in lower vertebrate by contraction melanin in melanophores • mammals— o fat metabolism, synthesis of melanin o Raise excitability of neurons in CNS, probably affects learning. endorphins—inhibit pain 1 5 Pineal Gland • Near center of brain. • Secrete melatonin. • light sensitive cells. • Night • Winter 15 1 6 Figure 45.7 Two thyroid hormones Animation 16 Pineal Gland Near center of brain secretes melatonin light sensitive cells or connect to eyes. melatonin • Inhibited by exposure to light, secreted at night • secreted in winter • Amount secreted coordinates with length of night • Coordinates biological clock (circadian rhythm) • Targets Superchiasmatic Nucleus (SCN) in HT which functions as biological clock. • Seasonal activities--Reproduction o inhibits gonadotropins • Working night shift, jet lag, seasonal depression Thyroid Gland Figure 9 Two Lobes, around trachea, butterfly Thyroid hormone and Calcitonin Thyroid Hormone • Produce Triiodothyronine (T3) and Tetraiodothyronine (T4) • Mammals—secrete mostly T4, target cell converts to T3. • Growth and Mental Development • Maintain normal blood pressure, heart rate, muscle tone, digestion, reproduction • Metabolic rate—oxygen consumption/cellular metabolism • Low temp or low TH levelÆHT release thyrotropin releasing factorÆAP releases TSHÆstim release of TH o Uncouple resp/ATP generationÆheat o Breakdown of fats and carbsÆenergy o Promote Protein synthesis 1 7 Figure 45.8 Feedback control loops regulating the secretion of thyroid hormones T3 and T4 17 1 8 Figure 45.9 Hormonal control of calcium homeostasis in mammals 18 1 9 Figure 45.10 Glucose homeostasis maintained by insulin and glucagon 19 Role in Homeostasis • Regulated by concentration of TSH and T4. • Hyperthyroidism: high temp, sweat, decrease weight, high bp • Hypothyroidism: gain weight, lethargic, cold. • Goiter o enlarged thyroid o Deficient iodine o Can not synthesize TH, but brain keeps sending TSH. Figure 10 Regulation of Calcium Level • High Calcium o Thyroid releases CalcitoninÆreduce calcium uptake in kidney, stimulate deposit in bones. • Low Calcium o Parathyroid gland (embedded in thyroid) Release parathyroid hormone (PTH)Æ • Increase Calcium uptake in kidney • Stimulate Calcium release from bone. • Activate Vitamin D which acts with PTH on bone and intestine. Pancreas Figure 11 Both endocrine and exocrine (bicarbonate/digestive enzyme) functions • Islets of Langerhans—antagonistic hormones o alpha cells release glucagons o beta cells release insulin *insulin/glucagon are antagonistic • Insulin o Cause body cells to take glucose from blood o Liver cells—slow glycogen breakdown • Glucagon o Act only on liver o Glucose--.glycogen Glucose needs to remain ~90mg/100mL Diabetes mellitus—insulin deficiency or lack of response to insulin. Glucose in urine. Glucose present in body but can’t be utilized • Lose water in urine with glucoseÆthirst • Breakdown fat for energy b/c can’t use sugarsÆlower pH of blood Type I • • • • autoimmune on pancreas can’t produce insulin early onset insulin shots Type II • deficiency in insulin or receptors don’t bind • later in life • Control w/ diet and exercise. 2 0 Adrenal Gland Figure 12 Adjacent to Kidneys Two parts—cortex and medulla Adrenal Gland 20 Adrenal Medulla Responds to signals from nervous system Secrete epinephrine and norepinephrine (adrenaline/noradrenaline)—fight or flight • catecholamines—synthesized from Tyrosine. • Stress/dangerÆincrease glycogen breakdown and glucose release Æfatty acid release Ædilate bronchioles to increase oxygen delivery treat asthma and allergic reactions Æblood to muscle and away from skin/dig—vasoconstrict/dilate • • • stimulated by acetylcholine and nervous system Norepinephrine—sustain BP Epinephrine—heart/metabolic rate Adrenal Cortex Figure 12 • respond to endocrine signals, not nervous • react to stress • StressÆHT signals anterior pituitary to release ACTH ACTH stimulates Adrenal cortex to produce corticosteroids (hormonal steroids from adrenal cortex). • Corticosteroids (two types) o Glucocorticoid—glucose metabolism Respond to long term environmental challenge— cold, starvation example: cortisol produce glc from non carb(Protein) Deposit glycogen in liver Gluconeogenesis—convert fat, protein, lactateÆglucose Breakdown of skeletal muscle protein Raise blood pressure suppress immune system • use cortisone (synthetic drug) to decrease inflammation o Mineral Corticoid—from AC, regulate fluid/electrolytes by effect on ion transport. salt and water balance aldosteroneÆkidney reabsorb Na and waterÆincrease BP and BV. 2 1 Figure 45.12 The synthesis of catecholamine hormones Animation 21 2 2 Sex Hormones Figure 13-14 From Gonads Three Categories • androgens—from testes—testosterone • estrogens—from ovary, female reproductive system • progestins—preparation/maint of uterus Gonadotropins—control release of androgens and estrogens GnRH from HTÆFSH and LH from APÆhormones from gonads. Figure 45.13 Steroid hormones from the adrenal cortex and gonads 22 2 3 Figure 45.14 Stress and the adrenal gland 23 2 4 Response of Adrenal Gland Short Term • Epinephrine and Norepinephrine – – – – – – glycogenÆglucose increase blood glucose increase BP increase breathing rate increase metabolic rate changes in blood flow Long Term • Mineral Corticoids (aldosterone) – retain Na+ and H2O – increase blood volume – increase BP • Glucocorticoids (Cortisol) – breakdown fat and protein to produce carbohydrates – suppress immune system 24