Ch.10 Endocrine System

1. Ch.10 Endocrine System By: Tyler Longmore, Alhi Leconte, & Christian khawly

2. Endocrine Glands • The Endocrine System consists of glands and tissues that secrete hormones • Hormones: Chemical signals that affect the glands or tissues . • Endocrine glands: ductless; they secrete their hormones directly into tissue fluid and from there go to the bloodstream to spread through the body.

4. How Hormones Function • They’re two different types of hormones: Peptide and steroid. • Along with fundamental differences in structure they both function differently. • Peptide hormones bind to a receptor protein in the plasma membrane and activate the second messenger system • The second messenger causes the cellular changes for which the hormone is credited

5. How Hormones Function Cont. • Peptide acts like “the boss” hormone that stays outside the cell and directs activities • Steroid hormones are lipids and diffuse across membranes only after they are inside the cell they produce hormones such as estrogen and progesterone that bind into receptor proteins

7. Hormones and Homeostasis • The release of hormones is usually controlled by one or more of three mechanisms • Negative feedback controls hormone release • Hormone release is controlled by actions of other hormones • Hormone release is controlled by the nervous system • The majority is from negative feedback • Hormone release may also be controlled by specific stimulating or inhibiting hormones

8. Hormones and Homeostasis Cont. • The nervous is an important controller of the endocrine system upon receiving sensory information from the body, the brain can make appropriate adjustments to hormone secretion to ensure homeostasis. For example when you eat a meal the brain signals parasympathetic neurons (controls rest and digest functions) to release the hormone insulin.

9. Hypothalamus And Pituitary Gland • The hypothalamus regulates the internal environment by controlling heartbeat body temperature and water balance as well as the pituitary gland. • The pituitary gland is about 1 cm in diameter and is connected to the hypothalamus. (has two portions: posterior and anterior)

11. Posterior Pituitary • The back portion of the pituitary gland which secretes the hormone of oxytocin (increases uterine) and anti diuretic hormone (ADH; increases absorption of water by kidneys) • The lack of ADH results in a disorder called diabetes and insipidus which is the inability to concentrate the urine (overly dilute) potentially leading to dehydration.

12. Anterior Pituitary • The front portion of the pituitary gland. • The anterior produces hormones that influence growth, sexual development, skin pigmentation, thyroid function, and adrenocortical function. • The effects of under function of the anterior pituitary gland include dwarfism and a rare case of overfunction include overgrowth (Gigantism)

13. Thyroid And Parathyroid Gland • The thyroid gland is a gland located in the neck where it is attached to the trachea. The thyroid gland is composed of a large number of follicles each small spherical structures made of thyroid cells. • These cells are filled with Triiodothyronine(T3) and Thyroxine(T4) which are two forms of the thyroid hormone; T3 is thought to have greatest effect on body. • Thyroid hormones increase the matbolic rate. They do not specify on one organ, therefor they stimulate all cells in the body.

14. Thyroid And Parathyroid Gland Cont. • If the Thyroid fails to develop properly, a condition called Congenital Hypothyroidism results. • Congenital Hypothyroidism: can lead to growth failure and permanent intellectual disability. Treatment consists of a daily dose of thyroid hormone (thyroxine) by mouth. Because the treatment is simple, effective, and inexpensive, nearly all of the developed world practices newborn screening to detect and treat congenital hypothyroidism in the first weeks of life. Manufactured by Iodine.

15. Thyroid And Parathyroid Gland Cont.2 • Hyperthyroidism: Over secretion of thyroid hormone, makes muscles swell, patients become hyper active, nervous, irritable, and suffer from insomnia. • Grave’s disease is a condition caused by excessive thyroid hormone.

16. Calcitonin • Calcium plays a significant role in the nervous conduction and muscle contraction as well as clotting of blood. • Calcitonin is a hormone secreted by the Thyroid glands when blood calcium levels rise. Its main job is to bring and deposit calcium to the bones.

17. Parathyroid Glands • Parathyroid Hormone(PTH): a polypeptide hormone, produced in the parathyroid glands, that helps regulate the blood levels of calcium and phosphate.

18. Adrenal Glands • Sit atop the kidneys • Each adrenal gland consists of an adrenal medulla (inner portion) and an adrenal cortex (outer portion) • The adrenal medulla is under nervous control, and the adrenal cortex is under the control of corticotropin (ACTH), an anterior pituitary hormone.

19. The Adrenal Medulla & Adrenal Cortex • The adrenal medulla produces epinephrine (adrenaline) and norepinephrine (non-adrenaline), which rapidly bring about all the body changes that occur when an individual reacts to an emergency situation • The adrenal cortex produces • Mineralocorticoids: regulate salt and water balance, leading to increases in blood volume and blood pressure • Glucocorticoids: regulate carbohydrate, protein, and fat metabolism, leading to an increase in blood glucose level

21. Glucocorticoids • Cortisol is a biologically significant glucocorticoid produced by the adrenal cortex • Cortisol promotes the breakdown of muscle proteins to amino acids, which are taken up by the liver from the bloodstream • Cortisol promotes the metabolism of fatty acids, which spares glucose for the brain • Cortisol counteracts the inflammatory response that leads to the pain and swelling of joints in arthritis and bursitis

22. Mineralocorticoids • The most important mineralocorticoid is aldosterone • Aldosterone primarily targets the kidney where it promotes renal absorption of sodium and water, and a renal excretion of potassium • Atrial natriuretic hormone (ANH) is a hormone released by cardiac cells and it hibits the secretion of aldosterone from the adrenal cortex

23. Malfunction of the Adrenal Cortex • A malfunction of the adrenal cortex can lead to a syndrome, a set of symptoms that occur together • Addison disease and Cushing’s syndrome are commonly associated with the adrenal cortex

24. Addison Disease & Cushing Syndrome • A person develops Addison disease when their adrenal cortex levels are low due to hyposecretion • A person develops Cushing syndrome when their adrenal cortex levels are high due to hypersecretion

25. Addison’s disease Cushing’s syndrome

26. Pancreas • Pancreatic islets, endocrine tissue, produce and secrete insulin and glucagon directly into the blood • Insulin is secreted when the blood glucose level is high, which occurs after eating • Glucagon is usually secreted between meals, when the blood glucose level is low

27. Diabetes Mellitus • Diabetes mellitus is a hormonal disease in which insulin-sensitive body cells are unable to take up and/or metabolize glucose • That causes the blood glucose level to elevate, which is called hyperglycemia • The person becomes extremely hungry due to a condition called polyphagia • Fat metabolism leads to the build up of ketones in the blood and the excretion of ketones in the urine • The build up of ketones in the blood could cause acidosis (acid blood), which can lead to coma and death

28. Diabetes Mellitus (continued) • There are 2 forms of diabetes mellitus • Insulin-dependent diabetes mellitus (IDDM): the pancreas does not produce insulin and the exposure to an environmental agent takes part in this • Noninsulin-dependent diabetes (NIDDM): usually occurs in people of any age who are obese and can be prevented or controlled by exercising regularly and maintaining a healthy weight

29. Other Endocrine Glands • The human body has many other endocrine glands, for example the gonads(testes/in males and ovaries/in females) • Hormones are also produced in lesser-knows glands, such as the thymus gland and the pineal gland • Prostaglandins are local messenger chemicals that individual body cells produce

30. Testes • Testes are located in the scrotum • They produce androgens (testosterone), the male sex hormones • Testosterone brings about and maintains the male secondary sex characteristics that develop during puberty • Some athletes take supplemental amounts of anabolic steroids, which are either testosterone or related chemicals

31. Ovaries • Ovaries are located in the pelvic cavity • They produce estrogen and progesterone, the female sex hormones • Estrogen is necessary for ovum maturation and for the secondary sex characteristics in females • Estrogen and progesterone take part in the development of females body

32. Thymus Gland • The lobular thymus gland lies just beneath the sternum • It reaches its largest size and is most active during childhood • Lymphocytes are white blood cells that originate in bone marrow and defend against a particular invader • After passing complete development in the thymus, lymphocytes are transformedintothymus-derived lymphocytes (T-lymphocytes) • The lobules of the thymus are lined by epithelial cells that secrete hormones called thymosins

33. Pineal Gland • The pineal gland is located in the brain • It produces the hormone melatonin, which is involved in the daily sleep-wake cycle • Circadian rhythms are daily 24-hour cycles that are controlled by an internal timing mechanism called a biological book

34. Hormones from Other Tissues • Leptin is a protein hormone produced by adipose tissue and it acts on the hypothalamus, where it signals that the individual has had enough to eat • A number of different types of organs and cells produce peptide growth factors, which stimulate cell division and mitosis • Prostaglandins are potent chemical produced within cells from arachidonate, a fatty acid • They are not distributed in the blood, they act locally and close to where they were produced

35. Other Endocrine Glands The body has a number of other glands • Such as the gonads • Testes in males And the ovaries in females • Lesser-known glands • Thymus gland • Pineal gland

36. Testes and ovaries • Testes are located in the scrotum • Produce androgens(testosterone) • Ovaries are located in the pelvic cavity • Produce estrogens and progesterone • The hypothalamus and pituitary gland control the hormonal secretions of these organs

37. Androgens • Puberty is the time when sexual maturation occurs meaning greatly increased testosterone secretion during this time period which also stimulates the growth of the penis, testes, growth of a beard, underarm hair and pubic hair. • It prompts the larynx and the vocal cords to enlarge and is also partially responsible for the muscular strength of males. • This is why some athletes take supplemental amounts of anabolic steroid which are either testosterone or related chemicals.

38. Estrogen and Progesterone • The female sex hormones have many effects on the body • The estrogen secreted during puberty stimulate the growth of the uterus and vagina. • Estrogen is necessary for ovum maturation and is responsible for female body hair and fat distribution. • Both Estrogen and Progesterone are required for beast development and for regulation of the uterine cycle which includes monthly menstruation.

39. Thymus gland • Lies beneath the sternum • Reaches its largest size and is most active during childhood. • Lymphocytes are white blood cells that originate in the bone marrow and are responsible for specific defense against a particular invader • When lymphocytes pass complete development in the thymus they are transformed into thymus derived lymphocytes • The lobules of the thymus are lined by epithelial cells that secrete hormones called thymosins • Although the hormones secreted by the thymus ordinarily work only in the thymus researches hope that these hormones could be injected into AIDS or cancer patients where they would enhance T-lymphocyte function

40. Pineal Gland • Located in the brain • Produce the hormone melatonin primarily at night. • Involved in our daily sleep-wake cycle • When melatonin levels increase we grow sleepy and reverse when levels become low. • Daily 24 hour cycles such as this are called circadian rhythms, which are controlled by an internal timing mechanism called a biological clock

41. Growth Factors • Granulocyte and macrophage colony-stimulating factor-secreted by many different tissues . Causes bone marrow stem cells to form either granulocyte or macrophage cells depending on whether the concentration is high or low. • Platelet derived growth factor and nerve growth factor is released from platelets and form many other cell types. It helps in wound healing and causes an increase in the number of fibroblasts, smooth muscle cells, and certain cells of the nervous system. • Epidermal growth factor and nerve growth factor stimulate the cells indicated by their names as well as many other. These growth factors are also important in wound healing. • Tumor angiogenesis factor stimulates the formation of capillary networks and is released by tumor cells. One treatment for cancer is to prevent the activity of this growth factor

42. Prostaglandins • Potent chemical signals produced within cells from arachidonate, a fatty acid. • Not distributed in the blood, instead they act locally, close from where they are produced • In the uterus they cause the muscles to contract and may be involved in the pain and discomfort of menstruation.

43. Chemical Signals • In the human body some chemical signals such as traditional endocrine hormones and secretions of neurosecretory cells, act at a distance. • Others such as prostaglandins, growth factors and neurotransmitters, act locally • Whether humans have pheromones is understudy

44. Effects of aging • Two concerns often seen in the elderly are thyroid malfunctioning and diabetes mellitus.

45. Homeostasis • Hormones particularly help maintain homeostasis in several ways: • Help maintain level of nutrients • Help maintain blood volume and pressure by regulating the sodium content of the blood • Help maintain the blood calcium level • Help regulate fuel metabolism • And help regulate our response to the external environment.