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34 Lecture Ppt

  1. 1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 34 Coordination by Hormone Signaling
  2. 2. The Endocrine System Utilizes Chemical Signals 34-
  3. 3. 34.1 The endocrine and nervous systems work together <ul><li>Nervous system sends nerve impulses via nerve fiber directly to a target organ </li></ul><ul><li>Endocrine system uses blood vessels to send hormones, chemical messengers, to target organs </li></ul><ul><ul><li>Functions more slowly than nervous system </li></ul></ul><ul><li>Negative Feedback Mechanisms </li></ul><ul><ul><li>Systems use negative feedback mechanisms </li></ul></ul><ul><ul><li>Example: Sensory receptors signal a control center in the brain, which then sends nerve impulses to the arteriole walls so that they constrict, and blood pressure rises </li></ul></ul><ul><ul><ul><li>Now the sensory receptors are no longer stimulated, and no nerve impulses are generated </li></ul></ul></ul>34-
  4. 4. 34-
  5. 5. Figure 34.1 Modes of action of the nervous and endocrine systems 34-
  6. 6. 34.2 Hormones affect cellular metabolism <ul><li>Peptide hormone - includes peptides, proteins, glycoproteins, or modified amino acids </li></ul><ul><ul><li>Action of Peptide Hormones </li></ul></ul><ul><ul><ul><li>Hormone epinephrine binds to a receptor in the plasma membrane </li></ul></ul></ul><ul><ul><ul><li>Formation of cyclic adenosine monophosphate (cAMP) , a molecule that contains one phosphate group attached to adenosine </li></ul></ul></ul><ul><ul><ul><li>cAMP activates an enzyme cascade, a series of enzymes that amplify the effect of the molecule </li></ul></ul></ul><ul><ul><ul><li>Glycogen is broken down to glucose, which enters the bloodstream </li></ul></ul></ul><ul><ul><ul><ul><li>Because a peptide hormone never enters cell, it is called first messenger </li></ul></ul></ul></ul><ul><ul><ul><ul><li>cAMP, which sets the metabolic machinery in motion, is second messenger </li></ul></ul></ul></ul>34-
  7. 7. Figure 34.2A Action of peptide hormones 34-
  8. 8. Action of Peptide Hormones <ul><li>Steroid hormone - always same complex of four carbon rings, but each one has different side groups </li></ul><ul><ul><li>Do not bind to plasma membrane receptors, but are able to enter the cell because they are lipids </li></ul></ul><ul><ul><li>Once inside, steroid hormones bind to receptors, usually in the nucleus </li></ul></ul><ul><ul><li>Inside the nucleus, the hormone-receptor complex binds with DNA and activates transcription of certain portions of DNA </li></ul></ul><ul><ul><li>Translation of messenger RNA (mRNA) transcripts at ribosomes results in enzymes and other proteins that can carry out a response to the hormonal signal </li></ul></ul>34-
  9. 9. Figure 34.2B Action of steroid hormones 34-
  10. 10. 34.3 The vertebrate endocrine system includes diverse hormones <ul><li>Locations of the major endocrine glands </li></ul><ul><ul><li>Hypothalamus , a part of the brain, close proximity to pituitary </li></ul></ul><ul><ul><li>Pineal gland in the brain </li></ul></ul><ul><ul><li>Thyroid and parathyroids are in the neck </li></ul></ul><ul><ul><li>Thymus gland lies just beneath the breastbone in the thoracic cavity </li></ul></ul><ul><ul><li>Adrenal glands and pancreas are in the abdominal cavity </li></ul></ul><ul><ul><li>Gonads include ovaries , located in the pelvic cavity, and testes , located outside this cavity in the scrotum </li></ul></ul><ul><li>Secretion of hormones is controlled by negative feedback, in conjunction with antagonistic hormonal actions </li></ul><ul><ul><li>Example: An antagonistic hormone called calcitonin, produced by the thyroid gland, lowers the Ca 2 + below levels set by the hormone PTH </li></ul></ul>34-
  11. 11. Figure 34.3 The human endocrine system 34-
  12. 12. 34-
  13. 13. The Hypothalamus and Pituitary Are Central to the Endocrine System 34-
  14. 14. 34.4 The hypothalamus is a part of the nervous and endocrine systems <ul><li>Hypothalamus controls secretions of posterior pituitary and anterior pituitary </li></ul><ul><ul><li>Stalk-like structure connects the hypothalamus to the pituitary </li></ul></ul><ul><li>Hypothalamus and Posterior Pituitary </li></ul><ul><ul><li>Neurosecretory cells produce hormones antidiuretic hormone (ADH) and oxytocin </li></ul></ul><ul><ul><ul><li>When ADH reaches the kidneys it causes water to be reabsorbed </li></ul></ul></ul><ul><ul><li>Oxytocin causes uterine contractions during childbirth and milk letdown when a baby is nursing </li></ul></ul><ul><ul><ul><li>Controlled by positive feedback —the stimulus continues to bring about an effect that ever increases in intensity </li></ul></ul></ul><ul><li>Hypothalamus and Anterior Pituitary </li></ul><ul><ul><li>Hypothalamus controls anterior pituitary by producing hypothalamic releasing hormones </li></ul></ul><ul><ul><li>Example: One hypothalamic-releasing hormones stimulates the anterior pituitary to secrete a thyroid-stimulating hormone, and a hypothalamic-inhibiting hormone prevents the anterior pituitary from secreting prolactin </li></ul></ul>34-
  15. 15. Figure 34.4 The hypothalamus and pituitary gland 34-
  16. 16. 34.5 The anterior pituitary produces nontropic and tropic hormones <ul><li>Nontropic Hormones: Some hormones produced by the anterior pituitary are controlled by the hypothalamus </li></ul><ul><ul><li>Prolactin (PRL) causes the mammary glands in the breasts to develop and produce milk after child birth </li></ul></ul><ul><ul><li>Growth hormone (GH) promotes skeletal and muscular growth </li></ul></ul><ul><ul><li>Melanocyte-stimulating hormone (MSH) causes skin-color changes in vertebrates having melanophores </li></ul></ul><ul><li>Tropic Hormones: Four hormones produced by the anterior pituitary are called tropic hormones because they stimulate the activity of other endocrine glands </li></ul><ul><ul><li>Thyroid-stimulating hormone (TSH) stimulates the thyroid to produce thyroxine and triiodothyronine </li></ul></ul><ul><ul><li>Adrenocorticotropic hormone (ACTH) stimulates the adrenal cortex to produce glucocorticoid </li></ul></ul><ul><ul><li>Gonadotropic hormones (follicle-stimulating hormone, FSH, and luteinizing hormone, LH) stimulate the gonads—the testes in males and the ovaries in females—to produce gametes and sex hormones </li></ul></ul>34-
  17. 17. Figure 34.5 The hypothalamus-anterior pituitary-target gland control system 34-
  18. 18. Hormones Regulate Metabolism and Homeostasis 34-
  19. 19. 34.6 The adrenal glands respond to stress <ul><li>Two adrenal glands sit atop the kidneys </li></ul><ul><ul><li>Inner portion called the adrenal medulla and an outer portion called the adrenal cortex </li></ul></ul><ul><li>Adrenal Medulla </li></ul><ul><ul><li>The hypothalamus initiates nerve impulses that travel to the adrenal medulla, which then secretes its hormones </li></ul></ul><ul><ul><ul><li>Epinephrine (adrenaline) and norepinephrine (noradrenaline) bring about all the body changes that occur when an individual reacts to an emergency situation </li></ul></ul></ul><ul><li>Adrenal Cortex </li></ul><ul><ul><li>Secretes small amounts of male and female sex hormones </li></ul></ul><ul><ul><li>Produces the glucocorticoid and the mineralocorticoid hormones that provide a long-term response to stress </li></ul></ul><ul><ul><li>Cortisol - raises the blood glucose level by two means </li></ul></ul><ul><ul><ul><li>It promotes the breakdown of muscle proteins to amino acids </li></ul></ul></ul><ul><ul><ul><li>Promotes metabolism of fatty acids rather than carbohydrates </li></ul></ul></ul><ul><ul><li>Aldosterone - most important of the mineralocorticoids, targets the kidney, where it promotes renal absorption of sodium (Na + ) and excretion of potassium (K + ) </li></ul></ul>34-
  20. 20. Figure 34.6 Stress responses of the adrenal gland 34-
  21. 21. APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES 34.7 Glucocorticoid therapy can lead to Cushing syndrome <ul><li>When the level of adrenal cortex hormones is high due to hypersecretion, a person develops Cushing syndrome </li></ul><ul><ul><li>Excess cortisol results in a tendency toward diabetes mellitus as muscle protein is metabolized and subcutaneous fat is deposited in the midsection </li></ul></ul><ul><ul><li>Excess aldosterone and reabsorption of sodium and water by the kidneys lead to a basic blood pH and hypertension </li></ul></ul><ul><li>Some people develop Cushing syndrome due to a tumor in the adrenal cortex or anterior pituitary </li></ul><ul><ul><li>Normally, cortisol secretion normally fluctuates over the course of the day, but it stays high in Cushing patients </li></ul></ul><ul><li>Others develop Cushing syndrome because they are taking glucocorticoid drugs, which are often prescribed for medical conditions such as asthma, rheumatoid arthritis, and lupus </li></ul>34-
  22. 22. Figure 34.7 Patient with Cushing syndrome ( left ) before and ( right ) after treatment 34-
  23. 23. 34.8 The pancreas regulates the blood sugar level <ul><li>Pancreas - slender, pale-colored organ between the kidneys and near the duodenum of the small intestine </li></ul><ul><ul><li>Exocrine tissue produces and secretes digestive juices that travel to small intestine </li></ul></ul><ul><ul><li>Endocrine tissue ( pancreatic islets ) secretes insulin and glucagon directly into the blood </li></ul></ul><ul><li>Insulin is secreted when the blood glucose level is high, which usually occurs just after eating </li></ul><ul><ul><li>Stimulates uptake of glucose by cells </li></ul></ul><ul><li>Glucagon is secreted from the pancreas, usually between meals, when the blood glucose level is low </li></ul><ul><ul><li>Stimulates the liver to break down glycogen to glucose and to use fat and protein in preference to glucose as energy sources </li></ul></ul>34-
  24. 24. Figure 34.8 Regulation of blood glucose level 34-
  25. 25. APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES 34.9 Diabetes is becoming a very common ailment <ul><li>21 million people have now been diagnosed with diabetes in the U.S. </li></ul><ul><ul><li>Investigate whether a close relative has diabetes </li></ul></ul><ul><li>Symptoms </li></ul><ul><ul><li>Frequent urination, especially at night </li></ul></ul><ul><ul><li>Unusual hunger and/or thirst </li></ul></ul><ul><ul><li>Unexplained change in weight </li></ul></ul><ul><ul><li>Blurred vision </li></ul></ul><ul><ul><li>Sores that do not heal </li></ul></ul><ul><ul><li>Excessive fatigue </li></ul></ul><ul><li>Diabetes Type 1 and Type 2 </li></ul><ul><ul><li>Diabetes Type 1: Pancreas fails to secrete insulin because the cells that make insulin have died off </li></ul></ul><ul><ul><ul><li>Usually occurs after a viral infection </li></ul></ul></ul><ul><ul><li>Diabetes Type 2: Cells are resistant to insulin </li></ul></ul><ul><ul><ul><li>Caused by poor health habits associated with physical inactivity and excessive food intake leading to obesity </li></ul></ul></ul><ul><li>Treatment - People with diabetes must regularly check their blood sugar level, usually before meals and at bedtime </li></ul><ul><ul><li>Medication is available for diabetes type 2, but a healthy diet and </li></ul></ul><ul><ul><li>exercise can also help </li></ul></ul>34-
  26. 26. Figure 34.9 Testing the blood sugar level 34-
  27. 27. 34.10 The pineal gland is involved in biorhythms <ul><li>Pineal gland , which is located in the brain produces the hormone melatonin , primarily at night </li></ul><ul><ul><li>Melatonin is involved in our daily sleep-wake cycle </li></ul></ul><ul><ul><ul><li>Normally we grow sleepy at night when melatonin levels increase and awaken once daylight returns and melatonin levels are low </li></ul></ul></ul><ul><ul><ul><li>Because light suppresses melatonin secretion, the duration of secretion is longer in the winter than in the summer </li></ul></ul></ul><ul><li>Daily 24-hour cycles such as this are called circadian rhythms </li></ul><ul><ul><li>Circadian rhythms are controlled by an internal timing mechanism called a biological clock </li></ul></ul><ul><li>Research indicates that melatonin also regulates sexual development </li></ul><ul><ul><li>Researchers have noted that children whose pineal gland has been destroyed due to a brain tumor experience early puberty </li></ul></ul>34-
  28. 28. Figure 34.10 Melatonin production 34-
  29. 29. 34.11 The thyroid regulates development and increases the metabolic rate <ul><li>Thyroid gland - located in the neck and consists of two distinct lobes connected by a slender isthmus </li></ul><ul><ul><li>Each lobe has a large number of follicles filled with the thyroid hormones triiodothyronine (T 3 ) and thyroxine (T 4 ), which increase metabolic rate </li></ul></ul><ul><li>Hypothyroidism </li></ul><ul><ul><li>Low levels of T 3 and T 4 results in hypothyroidism and slowing of metabolism </li></ul></ul><ul><ul><li>Children with congenital hypothyroidism (cretinism) are short and stocky </li></ul></ul><ul><ul><li>In adults it can result due to lack of iodine in the diet resulting in a simple goiter </li></ul></ul><ul><ul><li>Myxedema, a type of hypothyroidism that results in skin puffiness, lethargy and weight gain </li></ul></ul><ul><li>Hyperthyroidism - Graves disease </li></ul><ul><ul><li>Thyroid is overactive, and exophthalmic goiter forms </li></ul></ul><ul><ul><li>Eyes protrude (exophthalmos) because of edema in the eye socket </li></ul></ul><ul><ul><li>Patient becomes hyperactive, nervous, and irritable, with insomnia </li></ul></ul>34-
  30. 30. <ul><li>Figure 34.11A Congenital Figure 34.11B Simple goiter </li></ul><ul><li>hypothyroidism </li></ul>34-
  31. 31. Figure 34.11C Exophthalmic goiter 34-
  32. 32. 34.12 The thyroid and the parathyroids regulate the blood calcium level <ul><li>Blood calcium level is regulated in part by calcitonin , a hormone secreted by the thyroid gland </li></ul><ul><ul><li>Primary effect of calcitonin is to bring about the deposit of calcium in the bones when the blood calcium level rises </li></ul></ul><ul><ul><ul><li>Thereafter, the blood calcium level falls </li></ul></ul></ul><ul><li>Parathyroid glands are embedded adjacent to the thyroid gland </li></ul><ul><ul><li>Parathyroid hormone causes the blood phosphate (HPO 4 2+ ) level to decrease and the blood calcium level to increase </li></ul></ul><ul><ul><li>PTH promotes the release of calcium from the bones when the blood calcium level lowers </li></ul></ul><ul><ul><li>Also promotes the reabsorption of calcium by the kidneys, where it activates vitamin D </li></ul></ul>34-
  33. 33. Connecting the Concepts: Chapter 34 <ul><li>Nervous and endocrine systems are structurally and functionally related </li></ul><ul><ul><li>Hypothalamus, a portion of the brain, controls the pituitary, an endocrine gland </li></ul></ul><ul><ul><ul><li>Even produces the hormones that are released by the posterior pituitary </li></ul></ul></ul><ul><ul><ul><li>Also stimulates the release of hormones by the adrenal medulla </li></ul></ul></ul><ul><ul><li>Neurosecretory cells in the hypothalamus produce chemical signals that control the activity of the anterior pituitary </li></ul></ul><ul><li>Nervous system is well known for bringing about an immediate response to environmental stimuli </li></ul><ul><ul><li>Chemical signals released by the nervous system, called neurotransmitters, help maintain homeostasis </li></ul></ul><ul><ul><li>Heart rate, breathing rate, and blood pressure are all regulated to stay relatively constant </li></ul></ul><ul><li>Hormones released by endocrine glands also help maintain homeostasis by keeping the levels of calcium, sodium, glucose, and other blood constituents within normal limits </li></ul><ul><ul><li>Endocrine system is slower acting than the nervous system and often regulates processes that occur over days or even months </li></ul></ul><ul><ul><li>Hormones secreted into the bloodstream control whole-body processes, such as growth and reproduction </li></ul></ul>34-