1. Chapter 10

2.  Contributes to:  control of growth, development, reproduction, behaviour, energy metabolism, and water balance  By:  Secreting hormones  To control  Organ and tissue functions

3.  A system of ductless secretory organs (glands) located in various parts of the body  Include  Pineal, anterior/posterior pituitary, thyroid, parathyroid, thymus, adrenal, islets of Langerhans, ovaries, testes, mammary  Main function  Secrete hormones directly into the blood or extracellular fluid

4.  Is not a gland but a region of the brain  Part of the nervous system  Very important for function of endocrine system  Produce neurohormones that stimulate or inhibit production of other hormones in the pituitary gland

5.  Thyrotropin-releasing hormone (TRH)  Stimulates release of thyroid-stimulating hormone (TSH)  Gonadotropin-releasing hormone (GnRH)  Stimulates release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH)  Growth hormone-releasing hormone (GHRH)  Stimulates release of growth hormone (GH)  Corticotropin-releasing hormone (CRH)  Release of adrenocorticotropic hormone (ACTH)  Somatosin  Inhibits the release of growth hormone (GH)  Dopamine  Inhibits the release of thyroid-stimulating hormone (TSH)

6.  Chemical management system for the body  Chemicals produced by cells in one part of the body the regulate the processes of cells in another part of the body  Chemical messengers – act on cells from another part of the body  Local regulators – act on nearby cells  Self regulators – cells that produce chemicals to stimulate their own cellular processes

8.  Produced and secreted by cells, tissues and organs that compose the endocrine system (glands) directly into the blood or extracellular fluid  Hormones are circulated throughout the body  Only target cells will respond to specific hormones  Hormones are broken down by enzymes in target cell, liver or kidneys where they are reused or excreted

9.  Secreted in an inactive form – prohormones  Prohormones are converted by target cells or by enzymes in the blood to an active form  Angiotensinogen → angiotensin

10.  Protein hormones  Consist of AA – 3 to 200 in length  Usually hydrophilic – water soluble  Diffuse well through blood  Steroid hormones  Derived from cholesterol  Not water soluble  Usually encased with protein to travel through blood  Pass easily through lipid bilayer

11.  Water-Soluble  Cannot pass membrane  Bind to receptor molecules in the cell membrane  Signal is activated  Secondary messenger is activated  Change is caused inside cell  Acts in the cytosol or the nucleus  Glucagon  Breakdown of glycogen into glucose

13.  Lipid-Soluble  Can pass membrane (lipid)  Bind to receptors inside a cell (cytosol or nucleus)  Turn on or off an action of a specific gene  Changes amount of protein that is synthesized by cell  Aldosterone  Increase sodium absorption → increases water retention → increase blood pressure

15.  Only the cells that contain surface or internal receptors for the hormones respond to the hormones  Once bound to their receptors, hormones produce a response by turning cellular processes on or off. They do this by altering the proteins that are functioning in or produced by the cell  Hormones are effective in very small concentrations because of the amplification that occurs in both the surface and internal receptor mechanisms  The response to a hormone differs among target organs and among species

16.  Secretion of hormones are regulated by negative feedback mechanisms  Hormones inhibit other hormones  Multiple hormones can be secreted at a time

18.  The Master Gland  Produces hormones that control most of the other endocrine glands

19.  Made up of anterior lobe and posterior lobe  Links endocrine system to nervous system via portal vein (hypothalamus)  Influenced by hypothalamus  Releasing hormones/inhibiting hormones

20. 2. portal vein 4. anterior pituitary gland 5. hypophyseal vein 6. posterior pituitary gland 8. pituitary stalk 9. capillary network 10. neurons 11. neurosecretory cells 12. hypothalamus

21.  Secretes 6 major hormones into the bloodstream which influence hormone secretion in other glands  Prolactin, growth hormone, thyroid-stimulating hormone, adrenocorticotropic hormone, follicle-stimulating hormone, luteinizing hormone  Other hormones produced  Melanocyte-stimulating hormone, endorphins

23.  Cell division, protein synthesis, bone growth  IGF – insulin growth factor that stimulates these functions  Also  Conversion of glycogen to glucose, fats to fatty acids – regulates levels in blood  Stimulates cells to take up FA, AA and limits muscle cells to take up glucose

24.  Underproduction – dwarfism  Overproduction – gigantism

28.  Causes darkening in humans causing the release of melanin in the skin and hair  Protects from UV rays

29.  Natural pain killers

30.  Stores and releases 2 major hormones into the bloodstream  Antidiuretic hormone (vasopressin), oxytocin  These hormones are produced by the hypothalamus and stored here

31.  Causes distal convoluted tubule to become permeable to water  Helps maintain water balance

33.  Located in the front of the throat and shaped like a bow tie  Secretes  thyroxine (T ₄), triiodothyronine, calcitonin

34.  Contains 4 iodine atoms  When iodine levels are low thyroid will continue to grow resulting in a goiter

35.  Protein hormone that lowers levels of Ca² ⁺ in blood

36.  4 spherical glands (size of a pea) located on each side of the posterior surface of the thyroid gland  Secretes  Parathyroid hormone

37.  Stimulates enzymes in kidneys to convert vitamin D into calcitrol increasing absorption of Ca² ⁺ and phosphates from food  Underproduction  Muscle cramps  Osteoporosis  Overproduction  Kidney stones

38.  Consist of two regions  Adrenal medulla – contains highly modified neuro-secretory neurons  Adrenal cortex – contains non- neural endocrine cells

39.  Secretes  Epinephrine, norepinephrine  These chemicals can act as hormones or neurotransmitters (transmit nerve signals)  Part of the “fight or flight” response

40.  Released when body encounters stresses  Epinephrine  Increase heart rate  glycogen and fat breakdown  Skeletal muscles, lungs blood vessels dilate increasing blood flow  Blood vessels everywhere else constrict  Blood pressure raises  Reduces water loss  Digestive system slows  Used to counter anaphylaxis

41.  Secretes  Aldosterone, cortisol

42.  Located near the centre of the brain  Regulates several biological rhythms  Photoreceptors in the eyes influence pineal gland – light inhibits melatonin secretion  Helps to synchronize biological clock  Secretes  melatonin

43.  Occurs automatically in our body  Pancreas – contain both exocrine/endocrine glands  Exocrine  secretes digestive enzymes into the small intestine  Endocrine  Islets of Langerhans - Secretes insulin (beta cells) and glucagon (alpha cells)

44.  Regulate the ability of most tissues in the body to metabolize fuel substances (glucose, fats, proteins)

45.  Secreted by beta cells  Lower blood glucose levels by  Acts on skeletal muscles, liver cells, adipose tissue (fat) to uptake glucose  In the Liver  Lowers fatty acid levels  promotes fatty acid uptake and storage in adipose tissue  Inhibits breakdown of fats into fatty acids  Lowers amino acid levels  Promotes protein synthesis  Inhibits breakdown of proteins

46.  Secreted by alpha cells  Increase blood glucose levels by  Stimulating breakdown of glycogen into glucose  Stimulates breakdown of fats into fatty acids  Stimulates breakdown of proteins into amino acids  Stimulate cells to use amino acids and non-carbohydrates to synthesize glucose

47.  Cortisol – Helps raise blood glucose levels using three mechanisms  Stimulate synthesis of glucose from fats and proteins  Reduce glucose uptake by the body cells except in the central nervous system  Promote breakdown of fats and proteins into fatty acids and amino acids as alternative fuels

49.  Hyperglycemia (above 200mg/dL of blood)  Blood glucose levels are too high  (norm 115-200mg/dL)  Symptoms  Frequent urination, sugar in the urine, vision problems, fatigue, weight loss  Hypoglycemia (below 70mg/dL of blood)  Blood glucose levels are too low  (norm 70-115mg/dL)  Symptoms  Nervousness, cold sweats, hunger, headaches, weakness

50.  High glucose levels in the blood caused by problems with insulin production  Symptoms  Frequent urination, increased thirst, increased appetite  Classified into three different types  Type 1  Type 2  Gestational

51.  Also called juvenile diabetes or insulin-dependant  Beta cells do not produce any insulin  Daily administration of insulin is required usually by injection or pump

52.  Reduced insulin production or the inability of insulin to bind to its receptors properly  Developed in adulthood and is associated with obesity  90% of diabetics have this type  Controlling diet and exercise helps restore normal levels of insulin production

53.  Occurs in about 2 to 10% of pregnant women  High blood glucose levels develop during pregnancy  Usually a temporary condition but does increase the risk of both mother and child developing later in life

54.  Gonads – sex glands  Males – testes  Females – ovaries  Sex hormones  Androgens, estrogens, progestins  Regulate development of  male and female reproductive systems, sexual characteristics, mating behaviour http://www.youtube.com/watch?v=_7rsH2loI Y8

55.  Pair of ovaries  Located in abdominal cavity  Produce female gametes (ova, eggs)  Produce estrogen and progesterone  FSH and LH from the pituitary gland stimulate the maturation of the follicles in the ovary and trigger ovulation

56.  Estradiol  Stimulates maturation of the sex organs at puberty  Development of secondary sexual characteristics – breast development, body hair, widening of pelvis  Sex drive

57.  Progesterone  Maintains uterus for implantation of a fertilized egg  Growth and development of an embryo

58.  Production and release of eggs (ova) by the ovaries  Releases oocytes - immature eggs that have undergone 1 meiotic division  Polar body is associated with it  Disintegrates quickly  Females produce up to 1 million  Only ~380 are ovulated before menopause

59.  Monthly release of one or a few developing oocytes into the oviduct  Burst of LH causes follicle to rupture  Ova becomes ovum  Moves through the oviduct (fallopian tubes) via cilia that line these tubes  Fertilization occurs here in the oviduct  undergoes second meiotic division only if penetrated by sperm cell producing a zygote  If not fertilized egg will degenerate

60.  Occurs from puberty to menopause  Involves release of a mature egg approx every 28 days  Coordinated with the menstrual cycle (month)  Prepares the uterus to implant the egg if fertilization occurs

62.  LH causes ruptured follicle to grow into an enlarged yellowish structure  Initiates luteal phase – prepares uterus to receive an egg  If egg is fertilized:  Acts as an endocrine gland- secretes estrogens, progesterone and inhibin  Progesterone – inhibits GnRH – FSH LH  Inhibin prevents secretion of FSH  If egg is not fertilized  Corpus luteum shrinks

63.  Begins at day 0  Results from the breakdown of the endometrium  Releases blood and tissue breakdown products from the uterus to the outside through the vagina  Day 4 or 5 – flow ceases and endometrium begins to grow again  Same hormones that control ovarian cycle control this cycle

64.  High levels of sex hormones stops  Late 40’s or early 50’s  Menstrual/Ovarian cycle stops  Side effects  Hot flashes, headaches, mood swings  Treated with HRT (hormone replacement therapy)

65.  Testes  Affect the development of male secondary characteristics  Secrete androgens (testosterone)  Stimulates puberty, facial hair, vocal cords, sex drive  Spermatogenesis – production of sperm  Release of testosterone in the body is controlled by LH which is controlled by GnRH

66.  Sperm development from spermatogonia  Takes about 9 to 10 weeks - spermatogonium to sperm  Testes produce about 130 million fertile sperm each day

67.  Leydig cells - secrete testosterone  Sertoli cells – supply nutrients to spermatocytes and seal them off from body’s blood supply  Coiled seminiferous tubules located in epididymis store mature sperm  Vas deferens – transport sperm upon ejaculation