animal hormones

  1. How does a negative feedback system work?
    • Sensor monitors the variable
    • control center compares magnitude of variable to the setpoint value, integrates the information, and controls the response of the effector system(s), which control the magnitude of the variable, bringing it back to set point
  2. what are the two primary types of controls of effectors in multicellular animals, and what do they do?
    • nerve cells that produce electrical impulses (that usually transmit information via neurotransmitters)
    • hormones that provide chemical signals
  3. What do chemical messages such as hormones do?
    they produce and coordinate anatomical, physiological, developmental and behavioral changes
  4. Where do hormones come from?
    they are secreted by endocrine cells (often in endocrine glands)
  5. What is the difference between hormones and nerve impulse transmission?
    • Hormones work much more slowly than nerve impulse transmission and are not useful for controlling rapid actions
    • hormones coordinate longer-term developmental processes such as reproductive cycles
  6. Endocrine
    cells or glands that do not have ducts leading to the outside of the body; they secrete their products directly into the extracellular fluid
  7. Exocrine glands
    have ducts that release their secretions into the gut, etc.
  8. Are all endocrine cells part or a gland?
    • No, some endocrine cells are single cells within a tissue
    • digestive hormones, for example are secreted by isolated endocrine cells in the wall of the stomach and small intestine
  9. endocrine glands
    Some endocrine cells aggregate into secretory organs called endocrine glands
  10. Endocrine system
    In vertebrates, nine major endocrine glands make up the endocrine system
  11. endocrine cells
    hormone secreting cells
  12. target cells
    • cells receiving the hormonal messages, they must have appropriate receptors
    • the binding of the receptor activates a response
  13. what characteristic determines hormone groups?
    • The distance over which teh signal operates distinguishes hormone groups
    • some act close to the release site, others at distant body locations
  14. circulating hormones
    • most hormones diffuse into the blood, which distributes them throughout the body
    • when the hormone message encounters a cell with the proper receptor, it binds and triggers a response
  15. What does the position on/in a cell of a receptor tell you about the hormone?
    It can tell you if it is water or lipid soluble and if it can diffuse across the cell membrane
  16. Local hormones
    • act locally
    • two types: autocrine, paracrine
  17. Autocrine hormones
    act on the secreting cell itself
  18. Growth factors
    • stimulate growth and differentiation of cells, are a major class fo paracrine hormones
    • also act as autocrine hormones: some of the hormone influences the cell that secreted it, preventing the cell from secreting too much hormone
  19. What are some major types of local hormones
    • growth factors
    • neurons may also be considered to be paracrine cells because they use chemicals called neurotransmitters to send messages to another cell
  20. Paracrine hormones
    • act on cells near the site of release
    • released in tiny amounts or inactivated rapidly by enzymes, or are taken up efficiently by local cells
    • they never get into the circulatory system
  21. What are the three main groups of hormones based on structure?
    • peptides or protiens
    • steroid hormones
    • amine hormones
  22. peptide or protein hormones
    • water soluble
    • transported by vesicles out of the cell that made them
    • their receptors are on the outside of the cell membrane of the target cell (they can't get into the cells)
  23. steroid hormones
    • lipid-soluble
    • can diffuse out of the cells that made them
    • in the blood they must be bound to carrier proteins
    • bc they can diffuse through the cell membrane their receptors are usually in the cytoplasm of the target cells
  24. amine hormones
    • derivatives of the amino acid tyrosine
    • most are water-soluble, but some are lipid-soluble
  25. lipid-soluble hormones
    • the receptors for lipid-soluble hormones are inside cells, either in the cytoplasm or in the nucleus
    • the action of lipid-soluble hormones is mediated by intracellular hormone receptors that usually alter gene expression
  26. water solublble hormone receptors
    large glycoproteins on the cell surface with three domains
  27. What are the three domains of water-soluble hormone receptors?
    • binding domain: projecting outside the plasma membrane
    • transmembrane domain: anchors the receptor in the membrane
    • cytoplasmic domain: extends into the cytoplasm of the cell
  28. How does the cytoplasmic domain initiate the target cells respone?
    It activates protein kinases or protein phosphotases (signal transduction cascades)
  29. What determines how a cell responds to a hormone?
    • responses to hormones depend on their receptors and target cells
    • the same hormone can cause different responses in different types of cells
  30. How does epinephrine act on different cells in the body?
    • in the heart, it stimulates faster (increases HR) and stronger (increases stroke volume) heartbeat (increase cardiac output)
    • blood vessels in some areas (gut, skin, etc.) constrict to send more blood to skeletal muscles
    • in the liver, glycogen is broken down to glucose to provide quick energy
    • in fat tissues, fats are mobilized as another energy source, fatty acids
  31. When in evolution did hormones arise and how do we know?
    • hormonal comunication arose early in evolution
    • all multicellular animals have chemical communication between cells, even sponges
    • plants also have hormones, mainly to control growty and development
  32. why must insects molt?
    because insects have rigid exoskeletons, they have episodic growth patterns and must molt periodically
  33. instar
    the growth stage between each molt
  34. How is molting regulated in insects
    two hormones, brain hormone and ecdysone (molting hormone) work together to regulate molting
  35. corpora cardiace
    pair of structures attached to the insect brain that store brain hormone
  36. prothoracic gland
    endocrine gland in the thorax of insects which receives brain hormone and releases ecdysone which stimulates molting
  37. corpora allata
    • the rear part of the insect head
    • produces juvenile hormone
  38. juvenile hormone
    • prevents molting to the adult stage
    • if it is present the insect molts into another juvenile instar
  39. complete metamorphosis
  40. pituitary gland
    • a link between the nervous system and many endocrine glands and plays a crucial role in the endocrine system
    • the pituitary gland sits in a depression at the bottom of the skull and is attached to the hypothalamus
    • made of two parts: anterior and posterior
  41. Posterior pituitary (neurohypophysis)
    • an extension of the hypothalamus and therefor neural tissue
    • releases 2 hormones: ADH, oxytocin
  42. Where are the hormones from the posterior pituitary made and how do they get into the gland?
    • they are made by neurons in the hypothalamus (and therefore are neurohormones) an are packaged in vesicles
    • the vesicles are transported down the axons of the neurons that made them and are stored in the posterior pituitary
    • this movement of vesicles is achieved by kinesin proteins, powered by ATP, that "walk" down the microtubules of the axon
  43. anterior pituitary (adenohypophysis)
    • forms from an inpocketing of the roof of the mouth (Rathke's pouch)
    • releases four tropic hormones which control (stimulate) activities of other endocrine glands
    • they are peptide and protein hormones
    • each is produced by a different type of pituitary cell
    • other peptide and protein anterior pituitary hormones influence tissues that are not endocrine glands
  44. Antidiuretic hormone (vasopressin)
    • the major function is to increase water conservation by the kidney
    • If there is a high level of ADH secretion, the kidneys reabsorb water, decreasing urine output
    • ADH stimulates increased aquaporins in the collecting ducts
    • if there is a low level of ADH secretion, the kidneys release water in dilute, high volume urine
    • ADH release by the posterior pituitary increases if blood pressure falls or blood becomes too salty
    • ADH also causes peripheral blood vessel constriction
  45. oxytocin
    • a major function of oxytocin is to stimulate uterine smooth muscle contraction for the birth process (Pitocin)
    • it also stimulates milk flow (stimulates smooth muscle for ejection of milk) in the mother's breasts
  46. What are the four types of tropic hormones?
    • thyrotropin
    • adrenocorticotropin
    • gonadotropins
    • lutenizing hormone and follicle stimulating hormone
  47. What nontropic hormones are produced by the anterior pituitary?
    • growth hormone
    • prolactin
    • melanocyte-stimulating hormone
    • endogenous opiodes endorphines and enkephalins
  48. growth hormone
    • acts on many tissues to promote growth
    • stimulates cells to take up amino acids
    • stimulates the liver to produce chemical messages (insulin-like growth factors) that stimulate bone and cartilage growth
  49. gigantism
    the result of overproduction of GH in children
  50. pituitary dwarfism
    • caused by the underproduction of GH
    • GH can now be produced by genetically engineered bacteria
  51. Prolactin
    • stimulates the production and, to a lesser extent, secretion of milk in female mammals
    • it is also important in pregnancy and, in males, has a role in controlling the endocrine functions of the testes
  52. endorphins and enkephalins
    • the body's natural opiates
    • in the brain, these molecules act as neurotransmitters to reduce pain in pain pathways
  53. What controls the anterior pituitary and how?
    • the anterior pituitary is controlled by neurohormones from the hypothalamus
    • the hypothalamus obtains data about body conditions and the external environment through both neuronal and hormonal signals
    • the hypothalamus and the anterior pituitary are connected by portal blood vessels
    • secretions from the hypothalamic nerves are transported by these blood vessels to the anterior pituitary
  54. Thyrotropin-releasing hormone (TRH)
    • from the hypothalamus
    • cuases anterior pituitary cells to release thyrotropin, which in turn stimulates the thyroid gland
  55. gonadotropin-releasing hormone (GnRH)
    causes the anterior pituitary to release tropic hormones that control gonad activity (follicle stimulating hormone and luteinizing hormone)
  56. What type of feedback system controls anterior pituitary cells and the hypothalamus?
    They are under negative feedback control by the hormones of the glands they stimulate
  57. Cortisol feedback system
    • cortisol is produced by the adrenal gland in response to adrenocorticotropin. It returns to the pituitary in the blood, and inhibits further release of adrenocorticotropin
    • Cortisol also exerts negative feedback control on the hypothalamu, inhibiting release of adrenocorticotropin-releasing hormone
    • however, higher brain input to the hypothalamus also controls circulating anterior pituitary hormone levels
  58. Thyroid gland
    • located near the trachea
    • another example of an endochrine
    • produces the hormone thyroxine in specialized structures called follicles
  59. thyroxine
    • two active forms T3 and T4 are made from tyrosine
    • T3: 3 I
    • T4: 4 I
    • more T4 is produced, but its can be converted to T3 by an enzyme in the blood
    • T3 is the more active form of the hormone
  60. Roles of thyroxine in metabolism
    • it stimulates the transcription of many genes in nearly all cells in the body. Theses include genes for enzymes of energy pathways, transport proteins, and structural proteins
    • it elevates metabolic rates in most cells and tissues (important in thermoregualtion)
    • it raises blood glucose and promotes the use of carbohydrates over fats for fuel
  61. Cretenism
    Irreversible neural damage and retardation caused by insufficient thyroxine after the 4th month of human fetal life which results in inadequate formation of the myelin sheath around the axons of neurons
  62. Controls of thyroxine
    • Thyrotropin (or TSH) from the anterior pituitary activates thyroid gland cells to produce thyroxine
    • Thyrotropin-releasing hormone (TRH) from the hypothalamus activates TSH-producing cells in the anterior pituitary
    • In a negative feedback loop, thyroxine inhibits the response of pituitary cells to TRH. Therefore, less TSH is released when levels are high, and more is released when levels are low
    • Thyroxin also feeds back to reduce TRH from the hypothalamus
  63. Goiter
    an enlarged thyroid gland associated with eigher very low (hypothyroidism) or very high (hyperthyroidism) levels of thyroxine
  64. What is the structure of a thyroid follicle?
    a thyroid follicle is a layer of epithelial cells surrounding a mass of glycoprotein called thyroglobulin
  65. Thyroglobulin
    contains iodinated tyrosines and is digested by the epithelial cells of the follicle to make thyroxine
  66. What happens if there is inadequate iodine present when thryoglobulin is made?
    • the released molecules will be neither T3 nor T4 and will not bind to appropriate receptors (including those in the hypothalamus and anterior pituitary)
    • Goiter occurs when thyroglobulin production is above normal and the follicles are enlarged
  67. Hypothyroid goiter
    • results when there is insufficient thyroxine to turn off TSH production
    • the most common cause is a deficiency of dietary iodine
    • with high TSH levels, the thyroid gland continues to produce nonfunctional thyroxine and becomes very large
    • the body symptoms of this condition are low metabolic rate, cold intolerance, and physical and mental sluggishness
  68. hyperthyroid goiter
    • results when the negative feedback mechanism fails even though blood levels of thyroxine are hight.
    • A common cause is an autoimmune disease in which an antibody to the TSH receptor is produced.
    • Common symptom is high metabolic rate.
  69. What three hormones control blood calcium
    calcitonin, parathyroid hormone and vitamine D
  70. Blood calcium regulation processes (3)
    • Deposition and absorption of bone
    • exceretion of calcium by hte kidneys
    • Absorption of calcium from the digestive tract
  71. Calcitonin
    • released by the thryroid gland acts to lower calcium levels in the blood
    • Calcitonin decreases osteoclast activity and stimulates the osteoblasts to take up calcium from the blood for bone growth
  72. Osteoclasts/Osteoblasts
    • Osteoclasts break down bone and release calcium to the blood
    • Osteoblasts secrete the protein matrix and use circulating calcium to build new bone. As bone is laid down the osteoblasts are surrounded and develop into osteocytes.
  73. parathyroid glands
    • embedded in the posterior surface of the thyroid glad
    • releases parathyroid hormone when blood Ca is low
  74. parathyroid hormone (PTH)
    • causes the osteoclases to dissolve bone and release calcium
    • promotes calcium resorption by the kidney to prevent loss in the urine
    • promoting vitamin D activation which stimulates the gut to absorb calcium from food
    • Acts on the kidneys to increase the elimination of phosphate to reduce the possibility of calcium phosphate salt precipitation (kidney stones)
  75. vitamin D
    • not actually a vitamin, produced by the body
    • activates to form (1,25) dihydroxyvitamin D, stimulated by PTH
    • The active form binds to cyctoplasmic receptors and forms transcription factors. in the digestive tract the transcription factors act to increase synthesis fo calcium pumps, calcium channels and calcium binding proteins, promoting uptake of calcium
    • In the kidneys and bone acts like PTH
    • Negative feedback to inhibit PTH
  76. medulary bone
    bone stored in egg laying female birds to store calcium , under the control of PTH
  77. Pancrease
    insulin and glucagon are produced in the pancrease in cell clusters called islets of Langerhans
  78. Insulin
    • required for glucose uptake by most cells but not nerve cells
    • inhibits lipase (lipid breakdown) in adipose tissue, and stimualtes amino acid uptake by cells
  79. Diabetes mellitus
    • type 1 - lack of the protein hormone insulin
    • type 2 - lack of insulin receptors on target cells
    • causes excessive urine production
  80. Diabetes insipidus
    hyposecreation of ADH (makes you pee more)
  81. glucagon
    stimulates liver to convert glycogen to glucose when glucose levels are low
  82. somatostatine
    • paracrine functions that inhibit both insulin and glucagon
    • slows the gut activites
    • inhibits release of GH and thyrotropin
  83. Andreanl glands
    made up of adrenal medulla and the adrenal cortex two seperate endocrine organs
  84. andrenal medulla
    • produces epinephrine and norepinephrine
    • developes from the nervous system and is under the control of the nervous system
  85. adrenal cortex
    under hormonal control mainly by adrenocorticotropin (ACTH) from the anterior pituitary
  86. beta blockers
    • prevent epi from binding to the beta-adrenergic recptors on target cells
    • used to reduce fight-or-flight response for heart patients
    • leaves alpha sites open for regulatory function
  87. corticosteroids
    • prodcues by the adrenal cortex using cholesterol
    • acts by stimulating transcription of certain genes
    • glucocorticoids
    • mineralocorticoids
    • SEX steroids
  88. glucocorticoids
    raise blood glucose concentrations and other aspects of fuel molecule metabolism
  89. mineralocorticoids
    infulence extracellular ionic (mainly Na and K) balance
  90. SEX steroids
    stimualte SEXUAL developement and reproductive activity. Under normal conditions theses are secreated in only minimal amounts by the adrenal cortex
  91. aldosterone
    • the main mineralocoritcoid stimulates the kidney to conserve sodium and excrete potassium
    • release is stimulated by angiotensin-II
  92. Renin
    release is stimulated by lo blood Na and or lo blood pressure
  93. Cortisol
    • the main glucocorticoid helps control blood levels of glucose and other energery sources and to mediate the body's response to stress
    • raises blood glucose by stimulating gluconeogenesis by the liver and inhibiting peripheral use of glucose (saving for neural tissue) mobilizes fatty acids from adipose tissue and increases blood (amino acid) from muscle for uptake and use in gluconeogenesis
    • stress response ensures that muscles have enough glucose for immediate response and brain has enough glucose to function
    • also blocks the immune system reactions which temporarily are less critical, can be used to reduce inflammation and allergy
  94. ACTH-RH
    from the hypothalamus to stimulate the release of ACTH which controls cortisol levels
  95. gastrin
    stimulates secretion of HCl and pepsin, increases motility of stomach
  96. Enterogastrone
    slows the movement of the stomach
  97. secretin
    releases bicarbonate solution from pancrease to neutralize HCl before it enters the intestines
  98. Luteinizing hormone (LH) and follicle-stimulating hormone (FSH)
    controls the SEX steroids released by the anterior pituitary
  99. Gonadotropin-releasing hormone (GnRH)
    released by the hypothamalus to stimulate the release of gonadotropins (LH and FSH)
  100. How/why does puberty start
    Starts when the hypothalamus becomes less sensitive to negative feedback by the SEX steroids
  101. corpus luteum
    remaining follices left over in the ovary during ovulation that function as an endocrine gland and produces estrogen and progesterone for about two weeks
  102. Estrus
    the state of sexual receptivity around the time of ovulation
  103. human chorionic gonadatropic (hCG)
    • similar to funcion in LH but only produced by cells covering the blastocyst
    • detected by pregnancy tests
  104. metlatonin
    produced by the pineal gland, released in dark
Card Set
animal hormones
notecards for the chapter 41 power point