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Biology 103 - Main points/Questions

Biology 103 - Main points/Questions. Remember Plant Hormones? What are the major human endocrine glands? What hormones do you need to know? How are hormones controlled?.

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Biology 103 - Main points/Questions

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  1. Biology 103 - Main points/Questions Remember Plant Hormones? What are the major human endocrine glands? What hormones do you need to know? How are hormones controlled?

  2. In Summer plants need to balance root and shoot growth - too much of either is a waste of resources. Do you remember how they do this?

  3. shoot tip gradient of auxin (high) • plants need to balance root and shoot growth – use AUXIN & CYTOKININ amounts (low) (high) gradient of cytokinin

  4. AUXIN! positive phototropism – controlled by …? Light!

  5. In fall plants need to respond to changing environmental cues to trigger leaf senescence (death).

  6. Figure 24.14 The effects of ethylene

  7. Hormone Signals in Animals • Used for longer term signals than neurons • Different cells respond to different hormones • Hormones often key for homeostasis

  8. 33.02 The Timescale over Which Chemical Messengers Work • CD33020.GIF

  9. There are three big advantages to using chemical hormones as messengers rather than speedy electrical signals (nervous) • chemical molecules can spread to all tissues via the blood • chemical signals can persist much longer than electrical ones • many different kinds of chemicals can act as hormones

  10. Balancing water concentration • The concentration of the urine is regulated to maintain homeostasis • Hormones are key signaling molecules in this process.

  11. Negative feedback loops fight dehydration.. Page. 626

  12. As you dehydrate you get thirsty (this is controlled by the nervous system) • Your body also releases a hormone ADH that signals to the kidneys. Where does water get reabsorbed in the kidney? Page. 626

  13. The 5 steps of urine formation • Pressure Filtration • Reabsorption of water • Selective reabsorption • Secretion • More water reabsorption

  14. Further reabsorption of water • Final step that balances water amounts • Water can be variably reabsorbed into blood from collecting duct • waters ability to be reabsorbed is controlled by a hormone called ADH – how?

  15. Hormone signaling is a series of simple steps • issuing the command – release of the hormone from a gland

  16. Issuing the command

  17. Hormone signaling is a series of simple steps • issuing the command • transporting the signal • most are transported through body by the blood

  18. Transport

  19. Hormone signaling is a series of simple steps • issuing the command • transporting the signal • hitting the target • hormone binds to a receptor on the target cell

  20. “hit the target”

  21. Hormone signaling is a series of simple steps • issuing the command • transporting the signal • hitting the target • having an effect • After binding the receptor protein changes shape and triggers a change in cell activity

  22. Two basic categories of hormones • ADH is a peptide hormone (remember a peptide bond? • Built of amino acids • The other class of hormones are steroid based • Steroids are lipids so can pass through membranes!

  23. Fat-soluble hormone Water- soluble hormone • Peptide based • Bind to receptor on membrane • Steroid • Transported attached to a protein • Bind to receptor inside the cell Transport protein Signal receptor TARGET CELL Signal receptor NUCLEUS (a) (b)

  24. Fat-soluble hormone Water- soluble hormone • Peptide based • Signals are often more transient (just in the cytoplasm) • May alter gene expression • Steroid • Mostly alter gene expression • Tend to be long lasting effects Transport protein Signal receptor TARGET CELL OR Signal receptor Cytoplasmic response Gene regulation Cytoplasmic response Gene regulation NUCLEUS (a) (b)

  25. Hormones are produced in glands throughout your body

  26. Coordination of Endocrine and Nervous Systems in Vertebrates • The hypothalamus receives information from the nervous system and initiates responses through the endocrine system • Attached to the hypothalamus is the pituitary gland composed of the posterior pituitary and anterior pituitary

  27. The posterior pituitary stores and secretes hormones that are made in the hypothalamus • The anterior pituitary makes and releases hormones under regulation of the hypothalamus

  28. The posterior pituitary contains cells that originate in the hypothalamus

  29. The hypothalamus and the posterior pituitary are connected by a tract of neurons • hormones are made by cell bodies in the hypothalamus & moved to posterior pituitary • antidiuretic hormone (ADH) regulates the kidney’s retention of water • oxytocin initiates uterine contractions during childbirth and milk release in mothers

  30. The anterior pituitary is a complete gland that produces the hormones that it secretes

  31. The Hypothalamus and the Pituitary The hypothalamus controls production and secretion of the anterior pituitary hormones by means of a family of special hormones • neurons in the hypothalamus secrete releasing hormones • they travel to the anterior pituitary through a special capillary system,

  32. Portal system of the anterior pituitary gland and hypothalamus

  33. The Anterior Pituitary Secretes seven different hormones some you already know about… • LH & FSH Some that are new to you… • TSH & GH

  34. Pituitary hormones

  35. Follicle-stimulating hormone (FSH) • in females, it triggers the maturation of egg cells and stimulates the release of estrogen • in males, it regulates sperm development • Luteinizing hormone (LH) • in females, it triggers ovulation of a mature egg • in males, it stimulates the gonads to produce testosterone

  36. (a) Control by hypothalamus Inhibited by combination of estrogen and progesterone Hypothalamus – Estrogen production feeds back on the signal that drives estrogen release Stimulated by high levelsof estrogen + GnRH Inhibited by low levels of estrogen Anterior pituitary – LH FSH Pituitary hormonesin blood (b) LH FSH FSH and LH stimulatefollicle to grow LH surge triggersovulation Ovarian cycle (c) Corpusluteum Degeneratingcorpus luteum Growing follicle Maturingfollicle Luteal phase Ovulation Follicular phase Days | | | | | | | | 20 25 14 15 28 5 10 0

  37. growth hormone (GH) • simulates the growth of muscle and bone throughout the body • Thyroid stimulating hormone (TSH) • Stimulates thyroid to produce thyroxin – a key control of metabolism

  38. Negative feedback (feedback inhibition) controls how target gland hormones in the anterior pituitary are produced • when enough of the target hormone has been produced, the hormone then feeds back to the hypothalamus and inhibits the release of stimulating hormones from the hypothalamus and the anterior pituitary

  39. Thyroxine • Modifies metabolic rate • Requires iodine • What if you don’t have enough iodine?

  40. Fig. 35.11.b

  41. Hormones are key players in maintaining homeostasis • Commonly used as signals in negative feedback loops • Remember Insulin & Glucagon?

  42. Insulin and Glucagon: Control of Blood Glucose • Insulin and glucagon are antagonistic hormones that help maintain glucose homeostasis • The pancreas has clusters of cells that produce glucagon and insulin

  43. Body cells take up more glucose. Insulin Beta cells of pancreas release insulin into the blood. Liver takes up glucose and stores it as glycogen. STIMULUS: Blood glucose level rises. Blood glucose level declines. Homeostasis: Blood glucose level (about 90 mg/100 mL) STIMULUS: Blood glucose level falls. Blood glucose level rises. Alpha cells of pancreas release glucagon. Liverbreaks downglycogen andreleases glucose. Glucagon

  44. Control of Blood Calcium • Two antagonistic hormones regulate calcium (Ca2+) in the blood of mammals • Parathyroid hormone (PTH) causes blood calcium levels to increase • Calcitonin causes blood calcium levels to decrease.

  45. PTH increases the level of blood Ca2+ • It releases Ca2+ from bone and stimulates reabsorption of Ca2+ in the kidneys • It also has an indirect effect, stimulating the kidneys to activate vitamin D, which promotes intestinal uptake of Ca2+ from food • Calcitonin decreases level of blood Ca2+ • It stimulates Ca2+ deposition in bones and secretion by kidneys

  46. Draw the two negative feedback loops that involve these two hormones Increasing Blood Calcium level Blood Calcium level(about 10mg/100ml) Decreasing Blood Calcium level

  47. Calcium Regulation • What happens when calcium levels drop? • Parathyroid hormone (PTH) is secreted & causes bone cells to release calcium from the bones • PTH also stimulates calcium reabsorption by the kidneys and absorption by the gut • So dropping Ca++ leads to raising Ca++

  48. PTH Parathyroid gland(behind thyroid) STIMULUS: Falling bloodCa2+ level Homeostasis: Blood Ca2+ level(about 10 mg/100 mL)

  49. Fig. 45-20-2 Activevitamin D Stimulates Ca2+uptake in kidneys Increases Ca2+ uptake in intestines PTH Parathyroid gland(behind thyroid) Stimulates Ca2+ release from bones STIMULUS: Falling bloodCa2+ level Blood Ca2+level rises. Homeostasis: Blood Ca2+ level(about 10 mg/100 mL)

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