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The Endocrine System: Glands, Hormones, and Functions

Learn about the endocrine system, its glands, hormones, and their functions. Understand aging and pathology of the endocrine system.

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The Endocrine System: Glands, Hormones, and Functions

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  1. Chapter 7

  2. Anatomy and Physiology Chapter 7 The Endocrine Glands and Hormones

  3. Applied Learning Outcomes Use the terminology associated with the endocrine system Learn about hormones, glands, and their functions Understand the aging and pathology of the endocrine system Chapter 7 – The Endocrine Glands and Hormones

  4. Overview • The endocrine system is a complex collection of hormones that coordinate many of the body’s functions. • It is composed of glands that produce endocrine secretions. • Endocrine secretions are cellular signals that go directly into the blood. Chapter 7 – The Endocrine Glands and Hormones

  5. Jobs of the Endocrine System • Controls blood sugar • Maintains salt and water balance • Controls development and growth • Controls blood pressure and heart rate • Nervous system works with the endocrine system in response to danger and stress • Regulates metabolism • Determines gender and fertility • Controls human reproduction

  6. Glands • A group of cells that manufacture secretions. • Two types of glandular secretions • Exocrine- deposited into the body cavity or surface of skin through a tunnel of cells or ducts • Endocrine secretions typically sent into blood • Receive signals from environment (such as atmospheric gases, gravity, nutrients, sunlight, temperature) • Receives cellular signals or hormones that originate inside the body Almost any organ in the body can produce endocrine secretions.

  7. Endocrine System • Composed of 10 endocrine glands. • Called ductless glands • They do not travel through tubes. Enter blood stream. • Cells with certain receptors respond to endocrine secretions. • Target cells are cells that have these receptors.

  8. The Endocrine Glands – Pituitary and Pineal The pituitary gland is known as the master endocrine gland because its numerous hormones control most of the other endocrine glands and is intimately linked to the overall coordination of the body’s organ systems. The pineal gland is responsible for producing melatonin and serotonin. Chapter 7 – The Endocrine Glands and Hormones

  9. The Pituitary Gland and its Secretions Pituitary gland (Anterior) • Growth Hormone (GH) Affects Bone • Adrenocorticotropic hormone (ACTH) Affects Adrenal cortex • Thyroid stimulating hormone (TSH) Affects Thyroid gland • Follicle Stimulating Hormone (FSH) affects ovaries and testes • Lutenizing hormone (LH) affects ovaries and testes • Melanocyte stimulating hormone (MSH) affects Skin • Prolactin affects Mammary glands(PRL) Pituitary gland (Posterior) • Oxytocin affects Mammary glands(OT) • Oxytocin affects Uterus • Antidiuretic hormone (ADH) affects Kidney tubules

  10. Hormone Function • A ligand is a chemical that attaches to a receptor • Hormones are a category of ligands. • Hormones can attach to receptors on target cells internally or externally. • Surface receptors are located on the surface of the cell. • Internal receptors are located within a cell. • Surface receptors rely on blood’s watery fluid to carry the hormone to the cel membrane. • If hormone is the correct shape it will attach to the receptor on the cell membrane. • Causes changes within the target cell (effector)

  11. Internal receptors and how they work • Carrier proteins bring hormones to target cells (effectors) that use internal receptors. • One group of carrier proteins is created by the liver • They help to transport these hormones in the blood to the cell • Another group of carrier proteins produced in the cell attach the hormone to internal receptors on genetic material. • Transported hormones bind to a special receptor that interacts with the DNA • This interaction either switches on or switches off a distinct trait.

  12. Endocrine Secretions • Autocrine secretions are self governing and usually do not travel in the blood. They interact with the cell that produced them. • Paracrine secretions also travel a short distance via the blood or body fluid. They signal and target cells that are close by. • Endocrine secretions travel long distance via blood. They signal and target cells that are far away. • Pheromones are secretions that leave the body and signals the cells of other organisms.

  13. Cell Signaling

  14. Cell Signaling

  15. Negative feedback System • Most hormones work on a negative feedback system • Example is the hormone Thyroxine • Causes increase in metabolic rate. This causes body to • produce heat. • Thyroxine produced as long as body temperature is low. • Thyroxine shuts its own production off as body temperature • reaches a normal level. • Thyroxine is not produced unless body temperature drops. • http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter20/animation__positive_and_negative_feedback__quiz_1_.html

  16. Types of Hormones • Hormone- any chemical that signals a cell to alter its metabolism. • Agonists- are chemicals that act like hormones. • Example- foods that contain phytoestrogens act like estrogen in the body. • Antagonists- are chemicals that block the action of hormones. • Many chemical pollutants can interfere with hormonal communication because they mimic hormones.

  17. Types of Hormones • Two categories of hormones: • Peptide hormones • Composed of Amino acids • DNA contains program to build them • Usually responsible for rapid changes in the body • Most are involved in short term or immediate changes needed to regulate metabolism. • Some have permanent effects on body-ex. GH

  18. Types of hormones • Lipid hormones • Made from existing lipids in the body or taken in through diet. • Fewer types than peptide hormones • Valuable role in fluid regulation and sexual reproduction • Two types- hormone-like lipids and steroids. • Don’t travel as easily through the blood • A carrier molecule secreted into the blood moves them through the body • Readily crosses the plasma (cell) membrane. • Many lipid hormones have long term effects on body because they directly control DNA.

  19. The Endocrine Glands • The endocrine system is composed of 10 glands. • Hypothalamus • Pituitary Gland anterior and posterior 3. Pineal Gland 4. Adrenal Glands cortex and medulla 5. Thyroid Gland 6. Parathyroid Glands 7. Pancreas 8. Thymus 9. Ovaries 10. Testes • http://health.howstuffworks.com/human-body/systems/endocrine/adam-200091.htm

  20. Endocrine Glands • Hypothalamus • Located above the pituitary gland • Controls the endocrine activity mainly the pituitary • Also controls appetite, body temperature, and sleep. • Pituitary • Anterior controlled by releasing hormones from hypothalamus • Posterior is under nerve cell control of the hypothalamus Pineal • Produces the hormones • melatonin-involved with regulating body rhythms • serotonin-involved with appetite, emotions, moods and sleep.

  21. Endocrine Glands Adrenal Glands • Lie above each kidney • Two glands fused together • Adrenal cortex- the outer layer • Adrenal medulla- the inner layer • Adrenal Cortex • Produces Glucocorticosteroids • Regulate metabolism and inhibit ACTH • ACTH stimulates the secretion of cortisol • Cortisol helps metabolize lipids and proteins to produce energy • Produces mineralocorticosteroids • Regulate the balance of electrolytes and water in the body • Aldosterone is the major mineralcorticosteroid • It regulates potassium and sodium in the body • Necessary for muscle and nerve function

  22. Endocrine Glands • Adrenal Glands • Adrenal medulla • Produces Adrenaline (Epinephrine) • Produces Noradrenaline (Norepinephrine) • What causes the Adrenal glands to produce these hormones? • Heavy physical exertion • Stress • Low blood sugar • What effects do these hormones have on the body? • Increase the discharge of glucose and fats into the blood • (immediate energy needed to fuel metabolism • Adrenaline diverts blood away from many of the • body organs and to muscles. • “fight or flight” response • Elevates the metabolic rate of muscle cells • Increases blood pressure and heart function • Noradrenaline affects nerve cell function related to the body’s • response to activity and stress.

  23. Endocrine Glands • Thyroid and Parathyroid glands work together • Described as paired endocrine glands • Located just below and in front of the voice box in the middle of the neck Thyroid Gland • Under control of TSH • Low body temp and stress prompt release of TSH • Causes thyroid to release thyroxine • Thyroxine increases cellular metabolism • Too much Thyroxine: • Causes accelerated heart rate, fatigue, hair loss, light or absent menstrual periods, muscle weakness, trembling hands, and weight loss • Too little Thyroxine: • Causes cold intolerance, constipation, fatigue, irritability, memory loss, muscle cramps, and weight gain.

  24. Endocrine Glands • Thyroid Gland • Calcitonin produced by thyroid gland • Works with parathyroid glands to adjust calcium level in blood and bones • Calcitonin lowers blood calcium • Encourages retention of calcium in bone • Parathyroid Gland • PTH increases the calcium level in the blood by removing it from bone tissue • Stimulates vitamin D production which helps with calcium absorption. • Encourages kidneys to retain calcium and helps digestive system to absorb calcium

  25. Endocrine Glands • Pancreas • Large gland located under the stomach • Produces digestive enzymes for small intestines • Produces two hormones from endocrine cell clusters (islets) • Also produces hormones insulin and glucagon • Islets of Langerhans • Beta cells produce insulin • Alpha cells produce glucagon Insulin is made: • In response to high glucose levels • Insulin stimulates the insulin receptors • This causes the cells to take in the glucose • Insulin secretion speeds up the conversion of glucose into glycogen • Insulin also causes the body to store unused glucose as fat cells. • Improper insulin function can result in high blood glucose levels and cause blood vessel decay, dehydration, and kidney damage.

  26. Endocrine Glands • Pancreas: • Glucagon • Has the opposite role of insulin • Produced when we have low blood sugar (hypoglycemia) • Encourages the metabolism of fats and proteins for energy • As a way of preserving existing glucose until blood sugar levels return to normal.

  27. Endocrine Glands Gonads: Ovaries and Testes receive hormones from the pituitary gland. FSH promotes the formation of eggs and sperms. LH enables the maturation of eggs and sperm LH help males produce testosterone and females produce estrogen and progesterone. Testes produce testosterone. Ovaries produce estrogen and progesterone.

  28. Sex hormones in Females Estrogen give females secondary sex characteristics and also essential for bone maintenance. Adrenal glands of females are able to convert steroids into male hormones----androgens. It works with estrogen to promote muscle tone and also cause sex drive in females. Progesterone-works with estrogen to produce the menstrual cycle and induce changes during pregnancy.

  29. Sex Hormones in Males Testosterone produces male secondary sex characteristics ensures sperm maturation responsible for muscle development Abuse of anabolic steroids by athletes they are made up of chemicals resembling testosterone. High levels of testosterone can induce brain tumors cause cardiovascular problems males may be affected by baldness

  30. Pathology of the Endocrine System • Acromegaly • due to increase in GH in adulthood • Results in enlargement of skull, hands, feet, tongue • Abraham Lincoln may have had this. • Addison’s Disease • decrease in adrenal cortex hormones • due to malfunction of adrenal glands or pituitary gland • Results in darkening of the skin due to excess melanin production, dehydration, low blood pressure, low blood sugar, and sodium loss. • Cushing’s syndrome • Due to overproduction of adrenal cortex hormone due to malfunction or tumor of adrenal glands or Excess of ACTH secretions.

  31. Pathology of the Endocrine System Diabetes Insipidus Inadequate amount of ADH Produces extreme water loss due to frequent urination. Diabetes Mellitus Caused by decreased insulin production (Type I) or Body’s inability to detect insulin signals (Type II) Results in high blood sugar and a variety of disorders due to abnormal glucose levels Can lead to blindness, blood vessel destruction, kidney failure

  32. Pathology of the Endocrine System Hyperparathyroidism Overproduction of parathyroid hormone Caused by immune system disorders, kidney diseases, parathyroid tumors, pregnancy Produces elevated calcium levels, therefore calcium loss from bones. Results in kidney problems and weakening of bones Hypothyroidism Thyroid gland does not produce enough thyroxine In children it results in mental retardation and short stature In adults it causes lethargy, weight gain, dry hair and skin, and sensitivity to cold.

  33. Pathology of the Endocrine System Graves’ Disease (hyperthyroidism) caused by inflammation of thyroid gland due to elevated thyroid hormone. Caused by an autoimmune disease Results in elevated metabolic rate and feelings of nervousness or tension.

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