1. Unit A – Endocrine system

2. + whereas the nervous system makes short-term changes to restore homeostasis, the endocrine system works more slowly and tends to make more long-term changes + hypothalamus can be considered part of both the nervous and endocrine systems – hypothalamus regulates the pituitary gland, the master gland, through nerve stimulation – pituitary gland stimulates other endocrine glands secrete chemicals that affect the nerve activity of the hypothalamus

3. + chemical regulators, from the Greek word hormon which means “to set into motion” – hormones act to speed up or slow down body processes + produced in one part of the body, but affect another part + hormones do not affect all cells, only those with the correct receptor for that particular hormone + classified according to where they work (activation site) – most hormones target a specific target tissue  e.g. parathyroid hormone (regulates calcium levels)  e.g. gastrin (stimulates stomach cells to produce digestive enzymes) – non-target hormones affect cells throughout the body  e.g. human growth hormone (cause long bones to grow)  e.g. insulin (produced by the islets of Langerhans in the pancreas, secreted when blood sugar levels are high & regulates blood sugar)  e.g. epinephrine (adrenaline) (produced in times of stress)

4. + negative feedback control system – prevents chemical imbalances in the body – when a hormone causes a body response, it triggers receptors and the response is inhibited, restoring homeostasis – e.g. pituitary gland produces male LH (luteinizing hormone)  activates testosterone production in the testes  testosterone levels increase  high levels of testosterone inhibits the release of male LH + when negative feedback systems fail, medical disorders can result – e.g. gigantism results from a failure to turn off the production of growth hormone

5. stimulus high blood glucose responding gland pancreas Islet βcells hormone produced insulin target fat cells liver cells other cells effects conversion of glucose into glycogen glucose uptake result blood glucose falls negative feedback pancreas β cells no longer getting high blood glucose message stop producing insulin

6. Numbered: 1. Thyroid 2. Adrenal Cortex 3. Adrenal Medulla 4. Pancreas 5. Ovaries 6. Testes Not numbered: + hypothalamus + pituitary + parathyroid

7. + pituitary gland – controls all other endocrine glands – connected to the hypothalamus in the brain – composed of two lobes  posterior lobe (towards the back) ÷ receives hormones produced by the hypothalamus via special nerve cells ÷ stores and releases hormones into the blood when necessary = antidiuretic hormone (ADH) acts on the kidneys to increase water reabsorption by the kidney = oxytocin acts on the uterus to initiate strong contractions during labour acts on the mammary glands to trigger milk production

8. + anterior lobe (towards the front) – produces its own hormones – release of pituitary hormones regulated by the hypothalamus via other hormones  thyroid-stimulating hormone (TSH)  protein hormone ÷ stimulates thyroid gland to release thyroxine, which stimulates cell metabolism  corticotrophin adrenal steroid (ACTH)  steroid hormone ÷ stimulates adrenal cortex to release hormones involved in stress  growth hormone (GH) a.k.a. somatotropin  protein hormone ÷ targets most cells but effects are most pronounced in bones and cartilage, promotes growth ÷ disorders related to GH = dwarfism – underproduction of GH = gigantism – overproduction of GH = acromegaly – continued growth of jaw, forehead, fingers and toes into adulthood ÷ production inhibited when hypothalamus releases somatostatin

9.  follicle-stimulating hormone (FSH) ÷ in ovaries, stimulates follicle development ÷ in testes, promotes the development of sperm cells  luteinizing hormone (LH) ÷ in ovaries, stimulates ovulation ÷ in testes, stimulates the production of testosterone  prolactin (PRL) ÷ targets mammary glands and stimulates and maintains milk production ÷ production inhibited when hypothalamus releases dopamine

10. + located at the base of the neck in front of the windpipe + produce hormones involved in regulating metabolism and tissue growth and differentiation – thyroxine  promotes the oxidation of sugars and other nutrients ÷ 50% released as heat ÷ 50% converted to ATP  control of thyroxine ÷ receptors in hypothalamus are informed of low metabolic rate  thyroid-releasing factor (TRF) stimulates pituitary to release TSH  carried by blood to thyroid gland  thyroid releases thyroxine  stimulates cells to use more sugar ÷ high levels of thyroxine inhibits TRF from hypothalamus

11. + thyroid disorders – goiter  caused by low levels of iodine, a main component of thyroxine  thyroxine no longer completes negative feedback loop  TRF keeps being produced, so thyroid keeps being stimulated, causing it to enlarge  why table salt contains iodine (iodized salt) – hyperthyroidism  people with high thyroid activity are typically ÷ thin ÷ warm, ÷ overactive  excess glucose is converted to heat and ATP – hypothyroidism  people with low thyroid activity are typically ÷ less thin ÷ intolerant of the cold ÷ tend to have dry skin  because excess glucose is converted to fat once glycogen stores are full

12. + The parathyroid glands are small glands in the neck that produce parathyroid hormone. + Humans have four parathyroid glands, which are usually located behind the thyroid gland + control the amount of calcium in the blood and within the bones

13. + located above each kidney + each gland is composed of two smaller glands – adrenal medulla  inner gland,  stimulated by sympathetic nerves in times of stress  produces hormones that initiate fight-or-flight response ÷ epinephrine ÷ norepinephrine

14. + adrenal cortex – outer gland, surrounds adrenal medulla – produces two main types of hormones  glucocorticoids – e.g. cortisol ÷ affect blood glucose levels  mineralocorticoids – e.g. aldosterone ÷ help maintain body fluid levels + cortisol – help body recover from stress, increases amino acid levels in blood – converted into glucose by liver, or used in protein synthesis to repair damaged cells – as cortisol levels rise, cells within the hypothalamus and pituitary gland decrease the production of regulatory hormones and cortisol levels drop + aldosterone – increase sodium retention and water reabsorption by the kidney

15. + contains two types of cells – digestive enzyme producing cells – hormone producing cells  located in Islets of Langerhans + produce two hormones – insulin  produced in the beta cells  released when blood sugar level is high  makes liver and muscle cells permeable to glucose  in the liver, excess glucose is stored as glycogen, which helps return blood glucose levels to normal – glucagon  produced in the alpha cells  causes an increase in blood sugar levels after a period of fasting causes blood glucose to drop  promotes the conversion of glycogen back to glucose

17. + Several different types of diabetes exist, and there is often confusion on the part of the public about which type is which. + Unless “diabetes insipidus” is specified, it is assumed the type of diabetes being discussed is diabetes mellitus. + Type I and Type II diabetes are both subtypes of diabetes mellitus.

18. Diabetes InsipidusDiabetes Mellitus Also known as:  Type I  Juvenile diabetes  Insulin-dependent diabetes  Type II  Adult-onset diabetes Cause:  Body does not make/secrete enough ADH  Beta cells do not produce enough insulin  Tissues do not recognize the effect of insulin Area of dysfunction:  Hypothalamus, or posterior lobe of pituitary gland  Islet cells in pancreas  Body cells Symptoms:  Large volumes of urine  Dehydration  Thirst  Large volumes of urine  Dehydration  Thirst  Weight loss  Acetone-scented breath  Sweet-smelling urine Glucose in urine:NoYes Glucose levels in blood:UnaffectedHyperglycemia Treatment:  Anti-diuretic medications  Insulin replacement via injections  Islet transplants  Medications that make the body more sensitive to insulin

19. HormoneSourceFunctionControlled by Thyroid stimulating hormone (TSH) Anterior pituitaryStimulates thyroid to produce thyroxine Thyroxine levels in the blood ThyroxineThyroidRegulates metabolism in all cells Thyroxine levels in the blood CalcitoninThyroidReduces blood calciumCalcium levels in the blood Parathyroid hormone (PTH) ParathyroidIncreases blood calcium (released from bones) Calcium levels in the blood Adrenocortico- tropic hormone (ACTH) Anterior pituitaryStimulates adrenal cortex to release stress hormones Cortisol levels in the blood CortisolAdrenal cortexConverts amino acids into glucose during stress, reduces inflammation Glucose levels in the blood

20. HormoneSourceFunctionControlled by Human growth hormone (hGH) Anterior pituitaryStimulates growthHypothalamic hormones Antidiuretic hormone (ADH) HypothalamusPromotes water retention by the kidneys Water/salt balance Epinephrine (Adrenaline) Adrenal medullaPrepares body for stress Sympathetic nervous system AldosteroneAdrenal cortexIncreases salt uptake and water reabsorption Levels of Na+ and K+ in blood InsulinPancreas (β cells)Converts glucose to glycogen and increases cells’ uptake of glucose Glucose levels in the blood GlucagonPancreas (α cells)Converts glycogen into glucose to increase blood glucose levels Glucose levels in the blood