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Hormonal Control

Hormonal Control. IB DP Biology: Further Human Physiology. http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookendocr.html. Hormones are chemical messengers secreted by endocrine glands into the blood, and are carried by the blood to specific target cells.

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Hormonal Control

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  1. Hormonal Control IB DP Biology: Further Human Physiology http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookendocr.html

  2. Hormones are chemical messengers secreted by endocrine glands into the blood, and are carried by the blood to specific target cells. • How are these different than to exocrine glands? Steroids: estrogen, testosterone Proteins (peptides): insulin, ADA Tyrosine derivatives: thyroxin

  3. Steroid hormones (estrogen, testosterone) Cholesterol based & lipid soluble can pass through the Phospholipid bilayer easily. Click for animation Pass through the cell membrane Bind to receptor to form hormone-receptor complex Regulate gene transcription http://www.youtube.com/watch?v=Dxyq8GAWbpo

  4. Peptide hormones (insulin, ADH) Made from amino acids & water soluble can not pass through the phospholipidbilayer. Bind to receptors on cell surface. Secondary messenger released in the cell. Secondary messenger activates or inhibits enzymes.

  5. Steroid vs. Protein Hormones • Steroids enter cells and interact with genes directly. • Protein hormones bind to receptors in the membrane, which causes the release of a secondary messenger inside the cell.

  6. The hypothalamus & pituitary glands • Hypothalamus links nervous system to endocrine system. It controls the pituitary. • Pituitary secretes hormones. Pituitary http://forum.zeroinginonhealth.com/showthread.php?tid=1989

  7. Neurosecretory cells connect hypothalamus with pituitary. Produce release and release inhibiting hormones. Anterior (front) pituitary Secretes thyroxin, FSH, LH, growth hormones. Posterior (back) pituitary secretes ADH & oxytocin, http://www.growtall.com/endocrine2.htm

  8. Control of ADH (anti-diuretic hormone) secretion: Posterior Pituitary ADH is transported down axons and stored in nerve endings Osmoreceptors in hypothalamus detect blood plasma concentrations If blood plasma is too concentrated ADH is released into blood – blood plasma concentration is reduced and urine is hypertonic If blood is too dilute Neurosecretory cells do not release ADH. Blood ADH levels drop and concentration of plasma increases.

  9. Thyroxin is water soluble and lipophilic so it passes through the membrane. Click for animation http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter47/animations.html#

  10. Thyroxin increases metabolic rate This results in an increase in body temperature TRH – Thyrotropin releasing hormone TSH – Thyroxin Stimulating Hormone http://www.umm.edu/imagepages/8966.htm Control of body temperature involves the hypothalamus, thyroid, and the anterior pituitary. This is an example of negative feedback http://biologyinmotion.com/thyroid/

  11. The Control of Thyroxine by Negative Feedback • Thyrotropin releasing hormone (TRH) produced in the hypothalamus • Transported to the (anterior) pituitary in the portal vein • Secretion of thyroxine stimulating hormone (TSH) by the (anterior) pituitary • TSH brings about the secretion of thyroxine from the thyroid gland • two forms exist: T3, T4

  12. The Control of Thyroxine by Negative Feedback (continued) • Released into the bloodstream • Causes an increase in metabolic rate • Thyroxine inhibits the production/release of thyroxine releasing hormone/thyroxine stimulating hormone • Increased metabolic rate/rise in body temperature monitored by hypothalamus/causes decreased production of TRH • Thyroxine levels maintained within narrow limits

  13. Exocrine Structure Diagram • You should be able to draw a diagram of the structural features of exocrine glands showing: • secretory cells/acinus • secretory vesicles • lumen/duct/lumen of duct

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