Endocrine System

1. Endocrine System The endocrine system is one of the body’s main systems for communicating, controlling and coordinating the body’s work

2. Endocrine System • Control system that works along with the nervous system to regulate body functions and maintain homeostasis.

3. Endocrine System Vocabulary • Endocrinology – Science that deals with a group of ductless glands and the action of their secretions which are transported via the blood stream • Hormones - chemical messengers carried by the blood from endocrine glands to the cell upon which they act. (target cells) • The word “hormone” is derived from a Greek term that means to arouse to activity. • Endocrine glands vs. Exocrine glands • Exocrine glands secrete their products through ducts that lead to an open space • Salivary glands, Sweat glands, Gastric glands, Sebaceous gland glands • Endocrine glands secrete hormones directly into the bloodstream , no ducts involved • Thyroid gland, Pituitary, Parathyroid, Pancreas, Adrenals…

4. Endocrine gland

5. Overview of Endocrine System • Endocrine system includes all endocrine cells, tissues, and endocrine glands (organs) of the body • System of ductless glands that secrete hormones– chemical messengers/molecules • Circulate in blood • Act on target cells • Target cells respond to the hormones for which they have receptors • Effects are dependent on the programmed response of the target cells • Hormones are just molecular triggers

6. Overview of Endocrine System • Some organs are primarily endocrine organs/glands (pituitary, thyroid, parathyroid, adrenal, pineal) • Many different organs have some endocrine cells/tissues within their structure, but the organ’s primary function is not endocrine (ie: heart, kidney, digestive organs, pancreas, hypothalamus, gonads, thymus)

8. Classification of Hormones • Hormones classified based on their chemical structure

9. Secretion, Distribution & Effect of Hormones • Hormones are released on demand – only when needed • Hormone release is primarily regulated by negative feedback mechanisms • changes in ECF (ISF/plasma) concentration/composition • changes in circulating levels of hormone itself or regulating hormones • neural stimuli • Hormones secreted by endocrine cells into interstitial fluid, and distributed through bloodstream • Only cells that posses receptors for that particular hormone can be affected -“target cell/target organ” • Effect of hormones is on the metabolic activity of cells, via activation/inactivation of specific genes, or affecting protein synthesis

10. Secretion, Distribution & Effect of Hormones

11. Mechanisms of hormone release • Humoral: substances other than hormones control the secretion of endocrine glands ( nutrient, ion level) • Neural: nervous system stimulates the endocrine gland to release hormone • Hormonal: hormones from one gland stimulate the release of hormones from another gland

12. Hypothalamus & Pituitary Gland The pituitary gland, or hypophysis: • is an endocrine gland about the size of a pea and weighing 0.5 g (0.02 oz.) • It is a protrusion off the bottom of the hypothalamus at the base of the brain • rests in a small, bony cavity (sellaturcica) of the spheniod bone at the base of the brain • is connected to the hypothalamus small tube called the infundibular stem (Pituitary stalk). • has two functional lobes : the anterior and posterior pituitary • secretes hormones that regulate homeostasis.

13. Hormones released from the Pituitary Gland

14. Pituitary Gland – Posterior lobe Hormones: released hormones made by the hypothalamus Oxytocin Contractions uterus “let down” reflex – milk ejection Antidiuretic Hormone Retention of water Vasopressin effect , increase BP by constricting arterioles

15. Pituitary Gland – Anterior lobe Growth Hormone Stimulates cells to grow & divide Fat broken down to use as energy Maintain blood sugar homeostasis Insulin-Like Growth Factor - 1 • Bone growth • Protein synthesis Liver and other tissues

16. Pituitary Gland – Anterior lobe Prolactin (PRL) Stimulates/maintains milk production Unknown function in males

17. Pituitary Gland – Anterior lobe Gonadotropic Hormones: Follicle-Stimulating Hormone (FSH) & Luteinizing Hormone (LH) also known as Interstitial Cell Stimulating Hormone (ICSH) Ovaries: Estrogen Uterine lining growth Develop/maintain secondary sex characteristics Progesterone Uterine lining growth Testes: Androgens (Testosterone) Supports sperm and secondary sex characteristics Regulate hormonal activities of gonads Ovary Testicle

18. Pituitary Gland – Anterior lobe Thyrotrophic hormone or Thyroid Stimulating Hormone (TSH) Influences growth & activity of thyroid Thyroxine (T4) Stimulates metabolism Triiodothyronine (T3) Stimulates metabolism Calcitonin Decrease calcium levels

19. Pituitary Gland – Anterior lobe Adrenocorticotropic hormone (ACTH) Regulates activity of adrenal cortex Androgens Glucocorticoids Cortisone & cortisol Increase blood glucose Control inflammation Decrease edema Reduce pain Mineralocorticoids/Aldosterone Regulate water and electrolyte balance Adrenal medulla • Epinephrine & Norepinephrine • Increase heart rate • Increase blood glucose • Increase BP • Increase metabolic rate Short-term Stress Response Long-term Stress Response

20. Hormones released from the Pituitary Gland

21. Pineal Gland/Pineal Body Also known as the “third eye” Found in roof of the third ventricle of the brain Melatonin • Involved in rhythmic activities (day/night and seasonal)

22. Parathyroid gland Tiny masses of glandular tissue found on posterior surfaces of thyroid gland Parathyroid hormone (PTH) or Parathormone • Increases blood calcium levels • Stimulates osteoclasts to break down bone matrix to release calcium into the blood Thyroid gland Parathyroid gland

23. Thymus Gland Posterior to sternum, superior to the heart Large in infants and children, decreases in size throughout adulthood Thymosin • Programs “T” cells (Lymphocytes – a type of white blood cell) • Plays role in immunity

24. Pancreas Islets (Islets of Langerhans) • Formerly known as Islets of Langerhans or islands of Langerhans, irregularly shaped patches of endocrine tissue located within the pancreas Insulin (released from beta cells) • Reduces blood glucose level • Increases ability of cells to transport glucose across cell membrane Glucagon (released from alpha cells) • Raises blood glucose level

25. Other Hormone Producing Tissue and Organs Placenta Temporary organ Human Chorionic Gonadotropin • Stimulates production of estrogen and progesterone for maintenance of uterine lining

26. Other Hormone Producing Tissue and Organs Stomach Gastrin • Stimulates glands to release hydrochloric acid (HCl) Duodenum Intestinal Gastrin • Inhibits HCl secretion Secretin • Aids in functions related to digestion effecting pancreas, liver and stomach Cholecystokinin (CCK) • Aids in functions related to digestion effecting pancreas, gall bladder and duodenum

27. Other Hormone Producing Tissue and Organs Kidneys Erythroprotein • Effects bone marrow stimulates red blood cell production Vitamin D3 (Calcitriol) • Aids in the active transport of dietary calcium across intestinal cell membrane

28. Other Hormone Producing Tissue and Organs Heart Atrial Natriuretic Peptide (ANP) • Affects kidney by decreasing sodium reabsorption and releasing renin (enzyme that aid in increasing BP) • Affects adrenal cortex decreasing secretion of aldosterone

29. Endocrine gland & Hormone review A. • Name the gland. • Identify the hormone(s) released from gland. • Mechanism of stimulus/Regulated by?

30. Endocrine gland & Hormone review B. • Name the gland. • Identify the hormone(s) released form gland. • Mechanism of stimulus/Regulated by?

31. Endocrine gland & Hormone review C. • Name the gland. • Identify the hormone(s) released form gland. • Mechanism of stimulus/Regulated by?

32. Endocrine gland & Hormone review D. • Name the gland. • Identify the hormone(s) released form gland. • Mechanism of stimulus/Regulated by?

33. Endocrine gland & Hormone review E. • Name the gland. • Identify the hormone(s) released from gland. • Mechanism of stimulus/Regulated by?

34. Endocrine gland & Hormone review F. • Name the gland. • Identify the hormone(s) released form gland. • Mechanism of stimulus/Regulated by?

35. Endocrine gland & Hormone review G. • Name the gland. • Identify the hormone(s) released form gland. • Mechanism of stimulus?

36. Endocrine gland & Hormone review H. • Name the gland. • Identify the hormone(s) released from gland. • Mechanism of stimulus/Regulated by?

37. Endocrine Review Matching I 1. _____ Stimulate development of the follicle in the ovaries 2. _____ Stimulates the kidney to reabsorb water from urine 3. _____ Stimulates the thyroid gland 4. _____ Stimulates the adrenal cortex 5. _____ Promotes protein synthesis necessary for growth • FSH • GH • ACTH • TSH • ADH

38. Endocrine Review Matching II 1. _____ Increases blood glucose levels 2. _____ Decreases blood calcium levels 3. _____Regulates body metabolism 4. _____ Increases blood calcium levels 5. _____Regulate electrolyte balance • Aldosterone • Glucagon • Thyroxine • Calcitonin • Parathyroid hormone

39. Endocrine Review • Review chart in text pp. 270-271 to review major glands, hormone(s) released, hormone(s) chemical class, their actions and means of regulation. Continue on to learn about Factors that Affect Endocrine Function

40. Factors that Affect Endocrine Function Everyone's body undergoes changes, some natural and some not, that can affect the way the endocrine system works. Some of the factors that affect endocrine organs include: • aging • illness • stress • the environment • and genetics.

41. Aging Despite age-related changes, the endocrine system functions well in most older people. However, some changes do occur because of normal damage to cells during the aging process and genetically programmed cellular changes. These changes may alter the following: • hormone production and secretion • hormone metabolism (how quickly excess hormones are broken down and leave the body, for example, through urination) • hormone levels circulating in blood • biological activities • target cell or target tissue response to hormones • rhythms in the body, such as the menstrual cycle

42. Aging • For example, increasing age is thought to be related to the development of Type II diabetes. With aging, the target cell response time becomes slower, especially in people who might be at risk for this disorder. • The signs and symptoms of endocrine system diseases affect many body systems. In elderly persons, they are frequently subtle and may be harder to detect than in younger persons. At times, these signs are incorrectly linked with other causes, such as the changes of normal aging, other medical disorders or conditions, or drug therapy. • The aging process affects nearly every gland. For example, the hypothalamus is responsible for releasing hormones that stimulate the pituitary gland. During aging, there is either impaired secretion of some hypothalamic hormones or impaired pituitary response. These changes appear to influence the endocrine system's ability to respond to the body's internal environment. As a result, the body cannot respond as well either to internal or external stresses

43. Aging • With increasing age, the pituitary gland can become smaller and more fibrous and may not work as well. For example, production of growth hormone may decrease. This may lead to a hormone imbalance that causes problems such as decreased lean muscle, decreased heart function, and osteoporosis. • Aging can affect a woman's ovaries. These organs eventually exhibit the most common endocrine change related to aging: menopause. In menopause, the ovaries stop responding to follicle-stimulating hormone and luteinizing hormone from the anterior pituitary. Ovarian hormone production of estrogen and progesterone slows down and then stops. Eventually a woman stops having her periods altogether

44. Illness Illness may affect endocrine system function in several ways. Acute or chronic conditions may change endocrine functions. Chronic/Acute Conditions • Hormones are cleared from blood during their circulation to the target tissues. The liver and kidneys are primarily responsible for clearing hormones. Several clearance processes become altered or slowed in individuals who have chronic heart, liver, or kidney disorders. • Acute physical or mental stressors can trigger a preprogrammed stress response. The stress response is complex and can influence heart, kidney, liver, and endocrine system function.

45. Endocrine Pathologies Endocrine pathologies can result from the following: • congenital (birth) or genetic defects • surgery • traumatic injuries • cancerous and non-cancerous tumors • infection • autoimmune destruction (the immune system turns against the body's own organs and causes damage) • In general, endocrine pathologies create a hormone imbalance typified by either hyposecretion (underproduction) or hypersecretion(overproduction) of hormones. The underlying problem may be the endocrine gland itself or a source outside the gland.

46. Stress Many factors can start the stress response, but physical stressors are most important. In order for the body to respond to, and cope with, physical stress, the adrenal glands make more cortisol. If the adrenal glands do not respond, this can be a life-threatening problem. Some medically important factors causing a stress response are as follows: • trauma (severe injury) of any type • severe illness or infection • intense heat or cold • surgical procedures • serious diseases • allergic reactions • Other types of stress include emotional, social, or economic, but these do not require the body to produce high levels of cortisol in order to survive the stress.

47. External Factors • An environmental endocrine disruptor (EED) is a substance outside of the body that may cause adverse effects to normal function of the endocrine system. Some EEDs mimic natural hormone binding at the target cell receptor. These substances start the same processes between body cells that the natural hormone would start. EEDs of this type are referred to as hormone agonists. • Other EEDs block cellular events associated with hormone binding. These EEDs are called hormone antagonists. Still other EEDs can directly interfere with the production, storage, release, transport, clearance, binding, or elimination of endogenous hormones in the body. This can greatly affect the function of certain body systems.

48. External Factors There are currently over 84,000 commercial synthetic chemical substances in use around the world. At least 30,000 have been introduced into the U.S. environment since 1979. We do not know the extent to which they can interfere with the endocrine system and cause endocrine system diseases. Based on our knowledge of the effects of certain synthetic chemicals, such as DDT, diethylstilbestrol and PCBs, and the increasing evidence that reproductive function in wildlife and humans is changing, scientists are now examining a broad range of chemical effects. EEDs can affect people and animals in many ways: • disrupted sexual development • decreased fertility • birth defects • decreased hatching in animals • reduced immune response • neurological and behavioral changes, including reduced stress tolerance

49. Genetics • Portions of your endocrine system can be affected by genes. Genes are units of hereditary information passed from parent to child. Genes contain the instructions for the production of proteins, which are some of the essential components of the body. Genes are contained in chromosomes. The normal number of chromosomes is 46 (23 pairs). • Sometimes extra, missing, altered, or damaged chromosomes can result in diseases or conditions that affect hormone production or function. The 23rd pair, for example, is the sex chromosome pair. The mother and father each contribute a sex chromosome to the child. Girls have two X chromosomes (one from the mother and one from the father), while boys have one X (from mother) and one Y (from father) chromosome. Sometimes, however, a chromosome or piece of a chromosome may be missing. In Turner syndrome, only one normal X chromosome is present and this can cause poor growth. In another example, a child with Prader-Willi syndrome (PWS) may be missing all or part of chromosome 15, which also affects growth, metabolism, and puberty.

50. Genetics • Your genes also may place you at increased risk for certain diseases, such as breast cancer. Taking estrogen can cause breast tissue to grow faster. Cancer usually appears in fast-growing tissue. This is one of the ways that scientists believe that taking estrogen for symptoms of menopause may be related to developing breast cancer. Another idea is that breast tissue breaks down estrogen into chemicals that can bind to DNA (genetic material) and damage it. Damage to DNA is a common cause of cancer. At this time, it is not known exactly why estrogen might cause breast cancer or what role it does play in breast cancer growth.