Nervous and Endocrine Systems

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Nervous and Endocrine Systems
2011-04-20 22:19:24

Nervous System and Endocrine System and Fertiliaztion - Embryology
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  1. nervous v. endocrine system
    nervous = fast, direct, specific

    endocrine = slow, spread out, diverse
  2. Neurons depend on glucose. How is glucose diffused from blood to inside of neuron cell?
    facilitated diffusion
  3. Does neuron store glycogen and oxygen in order to convert it to glucose?

    it relies on blood to supply the nutrients
  4. Signal pathway across neuron:
    • dendrite = receives signal
    • axon hillock = generates action potential
    • axon = carries action potential to synapse
    • s synapse = carries signal to another cell
  5. What defines the resting potential?
    equilibrium of Na+/K+ pump across membrane
  6. How many Na+ and K+ pumped in/out of the cell in the sodium/potassium pump?
    3 Na+ out

    2 K+ in
  7. depolarization
    inside of the cell is more positive
  8. hyperpolarization
    inside of cell is more negative
  9. sodium voltage-gated channel:
    channel opens when voltage has reached the threshold

    flows Na+ ions into the cell = depolarization
  10. when cell is depolarized, what happens to potassium voltage-gated channels?
    they open and K+ ions flow out of the cell

    making inside less positive
  11. by the time K+ flows out, what is going on with Na+ channels?
    they are already closed
  12. What method returns the membrane to its resting potential?
    passive diffusion
  13. What must happen in order to propagate an action potential?
    stimulus to membrane must be greater than threshold.
  14. Action Potential is an All or Nothing!
  15. Which is faster, an electrical or chemical synapse?
  16. Once action potential has reached the synapse, what happens next?
    pre-synaptic cells holds vesicles with neurotransmitters
  17. How does pre-synaptic cell release neurotransmitter?
    Ca2+ voltage gated channels open and Ca2+ flow in

    Ca2+ releases neurotransmitter vesicles
  18. How are neurotransmitter vesicles released?
  19. How does post-synaptic cell receive the neurotransmitter?
    it has the corresponding receptor
  20. What happens if neurotransmitters are fired too often?
    it can't replenish neurotransmitter vesicles:

  21. What happens to neurotransmitter after post-synaptic cell has received its signal?
    degraded by enzymes

  22. Does a single synapse release more than one type of neurotransmitter?
  23. What kind of receptors?
    ion channels


    second messenger systems:
  24. second messenger systems (G-protein coupled)
    G protein is attached to receptor protein

    neurotransmitter stimulates protein and alpha subunit breaks off

    alpha subunit can open channels, activate enzymes, transcribe etc.
  25. saltatory conduction
    • AP down a myelinated axon jumps from one node of
    • Ranvier to the next quickly
  26. three functions of neurons
    • sensory
    • interneurons
    • motor
  27. afferent and efferent
    afferent = sensory

    efferent = motor
  28. sensory neurons do what?
    receive signals from receptor cell that interacts with its environments
  29. where is sensory neuron located?
    dorsal of spinal chord
  30. interneurons do what?
    transfer signals from neuron to neuron
  31. motor neurons do what?
    carry signals to muscle or gland
  32. where are motor neurons located?
    vertically of spinal chord
  33. CNS v. PNS
    CNS = interneurons (brain and spinal chord)

    PNS = sensory and motor neurons (everything else)
  34. PNS divisions
    somatic nervous system

    autonomic nervous system
  35. What kind of movement is somatic nervous system responsible for?
    voluntary movement

    innervates skeletal muscle
  36. What is automatic nervous system responsible for? How?
    involuntary action

    sensory ANS sends signals to motor ANS, which signals it to smooth muscle, cardiac muscle, or glands
  37. What controls the automatic nervous system?

    sympathetic and parasympathetic
  38. sympathetic v. parasympathetic
    sympathetic = fight or flight

    parasympathetic = rest and digest
  39. pre-ganglionic neurons in ANS (sympathetic and parasympathetic)
  40. post-ganglionic neurons in ANS (sympathetic and parasympathetic)
    sympathetic = epinephrine and noepinephrine

    parasympathetic = acetylcholine
  41. How can the time between heart beats be increased?
    increasing ACh
  42. Central Nervous System involves activity of
    brain and spinal chord
  43. lower brain
    medulla, hypothalamus, thalamus, cerebellum
  44. What is the lower brain responsible for?
    subconscious activities

    [respiratory, arterial pressure, salivation, emotions, reaction to pain/pleasure]
  45. What is the higher brain responsible for?
    stores memory and processes thoughts
  46. exocrine . endocrine
    exocrine = releases enzymes through ducts

    endocrine = releases hormones into blood
  47. Where are peptide hormones made?
    rough ER, cleaved in ER lumen, transported to Golgi
  48. How are peptide hormones secreted?
    stimulation by another hormone

  49. Do peptide hormones have difficulty passing through membrane of target cell?

    so they attach to a receptor, which can activate ion channel, activate other membrane protiens, activate intracellular second messenger
  50. example of peptide hormones
    anterior pituitary = FSH, LH, ACTh, TSH, Prolactin

    • posterior pituitary = ADH and oxytocin
    • parathyroid = PTH
    • pancreatic hormone = glucagon and insulin
  51. Where do steroid hormones come from?
    derived from cholesterol
  52. How do steroid hormones travel through the blood
  53. Do steroid hormones have difficulty passing membrane of target cell?
  54. Steroid effects on target cell
    diffuse easily through membrane and into cytosol

    acts at transcription level
  55. Where do steroid hormones bind?
    receptor protein in the cytosol

    then transported to nucleus
  56. tyrosine derivatives
    thyroid hormones and calecholamines (epinephrine and norepinephrine)
  57. thyroid hormones: lipid or protein like?
    lipid soluble, must be carried in the blood by plasma protein carriers

    transcription effects
  58. Why do thyroid hormone effects last long?
    they have high affinity to their binding proteins in the plasma

    create a latent period in nucleus
  59. epinephrine and norepinephrine: lipid or protien-like?
    water soluble and dissolve in blood

    bind to receptors on target tissue
  60. Effects on target cell of epinephrine and norepinephrine
    act mainly through second messenger cAMP
  61. If the conduct of an effector is given, is the hormone found going to be the one that is responding to the condition or the one creating it?

    (ex: aldosterone increases blood pressure. Would you expect aldosterone levels be high or low in a person with low blood pressure?)
    gland lags behind effect

    high aldosterone because the body tries to bring blood pressure back to normal
  62. Where are the hormones coming from (distinguish types of hormones)?
    • cortex = steroids
    • medulla = catecholamines
    • thyroid = tyrosine derivatives (thyroid and calcitonin)
  63. hormones released by anterior pituitary
    • hGH
    • ACTH
    • TSH
    • FSH
    • LGH
    • Prolactin

    all peptide hormones
  64. hGH
    human growth hormone

    increases amino acid transport across the cell membrane
  65. so what does hGH do, essentially?
    increases transcription and translation

    decreases breakdown of proteins
  66. ACTH
    stimulates adrenal cortex to release glucocorticoids
  67. What are glutocorticoids? When adrenal cortex releases glutocorticoids, what does it do to target cell?
    stress hormone

    adrenal cortex acts by a second messenger (cAMP)
  68. TSH

    what and how?
    stimulates thyroid to release T3 and T4

    through a second messenger: cAMP
  69. Prolactin
    promotes lactation (milk production) by the breasts

    *not milk ejection
  70. What inhibits prolactin before birth?
    progesterone and estrogen
  71. hormones released by posterior pituitary
    oxytocin and ADH

    mostly support tissue for nerve endings
  72. What kind of hormones are oxytocin and ADH? Where are they synthesized?
    peptide hormones

    • syntesized in neural cell bodies of hypothalamus
    • transported down axons to posterior pituitary
  73. oxytocin
    ejection of milk from breasts

    increases uterine concentration during pregnancy
  74. ADH
    makes collecting ducts in kidney permeable to water

    reduces the amount of urine and concentrating the urine
  75. What other effects does ADH have?
    increase in blood pressure (b/c it absorbs fluids)
  76. What are the adrenal glands?
    located on top of kidneys -

    cortex and medulla
  77. What does the adrenal cortex secrete?
    only steroid hormones

    [aldosterone and glucocorticoids]
  78. aldosterone
    increase in Na+ and Cl- reabsorption

    increase in K+ and H+ secretion
  79. how does aldosterone affect ion channels?
    increase protein production (a transcription factor)
  80. glucocorticoids
    increase blood glucose concentrations
  81. cortisol
    stimulates gluconeogenesis in liver to increase blood glucose concentration

    also degrades tissue to fatty acids for cell energy

    [stress hormone]
  82. What does the adrenal medulla secrete?
    catecholamines (epinephrine and norepinephrine)
  83. catecholamine effects
    similar to effects of sympathetic nervous system

    vasoconstrictors and vasodilators
  84. What does vasoconstrictors and vasodilators mean?
    constrict blood vessels to internal organs


    increase blood flow to skeletal muscles
  85. What hormones are secreted by the thyroid?
    T3 and T4 and calcitonin
  86. T3 and T4

    what kind of hormone? what does it do? how is it regulated?
    lipid soluble

    increases basal metabolic rate

    regulated by TSH
  87. calcitonin:
    what kind of hormone? what does it do?
    peptide hormone

    • slightly decreases blood calcium
    • builds bone mass
  88. Parathyroid secretes what hormone?

    peptide hormone

    • increases blood calcium
    • increases osteocyte absorption of calcium and phosphate
  89. Pancreas secretes what hormones? what kind of hormones are they?
    insulin and glucagon

    both peptide hormones
  90. insulin:

    released by? released when? what does it do?
    released by beta-cells of pancreas

    released when blood levels of carb. or proteins are high

    it lowers blood glucose levels
  91. glucagon:

    released by? what does it do? how?
    released by alpha-cells of pancreas

    stimulates glycogenolysis (breakdown of glycogen) in liver

    acts via 2nd messenger - raises blood glucose levels
  92. seminiferous tubules
    site of sperm production
  93. spermatogonia
    arise from epithelial tissue to become sperm
  94. What does LH do?
    stimulates leydig cells to release testosterone
  95. What is testosterone?
    the primary androgen (male sex hormone) -

    stimulates germ cells to become sperm
  96. spermatid becomes spermatozoon: what is the structure of spermatozoon?
    head, midpiece, and tail

    only head (nuclear protion + acrosome) enter the egg
  97. What provides the energy for movement of the tail?
    midpiece is filled with mitochondria
  98. Where does the spermatozoon mature?
  99. Upon ejaculation, where does the spermatozoa propel through?
    vas deferens - into urethra - out of penis
  100. What is semen?
    mixture of spermatozoa and fluid that leaves the penis upon ejaculation
  101. Where does this fluid come from?
    • seminal vesicles
    • prostate
    • bulbourethral glands
  102. Menstrual cycle
    begins after puberty: what are the steps -
  103. at puberty what does FSH do?
    stimulates growth of cells around primary oocyte

    [stuck in prophase I]
  104. zona pellucida
    growth of cells around primary oocyte stimulate zona pellucid around the egg
  105. What is the structure of the primary oocyte with growth and zone pellucida around it?
    primary follicle
  106. once the primary follicle is set what happens next?
    follicle grows further - consists of theca cells, growth of cells, and zona pellucid and the oocyte

    this is the secondary follicle
  107. What does LH do?
    stimulates theca cells to secrete androgen -
  108. What does FSH do?
    converts androgen into estradiol ( a kind of estrogen)

    estradiol is secreted to the blood
  109. What does the estradiol do?
    it prepares uterine wall for pregnancy

    that's why it's produced during menstrual cycle and secreted into the blood
  110. Just before ovulation, estradiol levels rise rapidly. What does this do?
    dramatic increase in LH secretion
  111. What is this increase in LH secretion called?
    luteal surge
  112. What does the luteal surge do? (rise in LH levels)
    causes the follicle to burst, releasing the egg
  113. The egg that is released due to the luteal surge is what kind?
    secondary oocyte
  114. What happens to the egg?
    it is swept to the Fallopian tube or oviduct
  115. What happens to the rest of the folicle
    it is left behind to become the corpus luteum
  116. What does the corpus luteum do?
    secretes estradiol and progesterone throughout pregnancy
  117. If not pregnant, corpus luteum....
    degrades into corpus ablicans
  118. Where does the egg go?
    it is taken up by the frimbriae in fallopian tube
  119. Is the egg the only thing that enters the fallopian tube?
    no, zona pellucida and some granulosa cells also enter
  120. After ovulation, what happens to secondary oocyte?
    begins the second meiotic division

    pauses at metaphase II until fertilization
  121. after the fallopian tube, where is the egg designated? and how?
    uterus by cilia
  122. How does sperm move?
    requires ATP

    sperm acrosome makes path
  123. Where does the sperm end up?
    cytoplasm of the oocyte

    prevents other sperm from fertilizing the same egg
  124. Now that the sperm and egg have met, what can occur?
    oocyte goes through second meitotic division
  125. What is the product of this second meiotic division?
    • ovum -
    • unites with sperm
  126. What is fertilization?
    when ovum and sperm fuse to form the zygote
  127. What is cleavage:
    zygote (still in fallopian tube) undergoes further mitotic division
  128. zygote comprised of 8 or more cells is called

    any of these 8 cells can produce a complete individual
  129. morula continues to divide forming....
    hollow ball with fluid - blastocyst
  130. what is it called when blastocyst enters uterus?
    implantation -

    said to be pregnant
  131. Upon implantation, egg secretes...
    HCG - human chorionic gonadotropin
  132. What does HCG do?
    prevents degeneration of the corpus luteum

    maintains secretion of estrogen and progesterone
  133. What happens next?
    placenta is formed
  134. By when does placenta reach full development?
    end of the first trimester
  135. What happens to HCG after placenta has developed?
    placenta can produce its own progesterone and estrogen

    so it lowers secretion of HCG
  136. gastrulation
    cells begin to move around slowly

    form 3 germ layers
  137. what are the germ layers? and their funcitons
    ectoderm: outer covering, nervous sys., sensory organs

    mesoderm: bone and muscle

    endoderm: lining of digestive tract and liver & pancreas
  138. neurulation
    notochord (mesoderm) induces the overlying ectoderm to thicken
  139. cell differentiation during development is extremely sensitive to:
    timing of mRNA turnover