Introduction Hypothalamus and Pituitary Gland- Exam I

  1. What is endocrinology?
    the study of the endocrine glands and these comprise the endocrine system of the body
  2. Endocrine Gland
    • a group of cells which synthesize chemicals and these chemicals are released into the surrounding medium (extracellular fluid) and typically into the blood
    • the chemicals are hormones
  3. Difference between endo and exocrine glands
    • endo: release into blood or extracellular fluid
    • exo: release into ducts that go usually to the outside of the body
  4. Categories of endocrine glands
    • Classic Endocrine Glands
    • Gastrointestinal Tract Glands
    • Central Nervous system
    • Placenta
    • Other organs have endocrine functions, but it is not their main function (ie- heart)
  5. Classic Endocrine glands
    • organs with the endocrine function as the main function
    • thyroid gland, ovaries, adrenal gland, etc
    • their major function is producing hormones
  6. How did scientists determine if an organ was a classic endocrine gland
    • by ablation (removal of the gland) and readministering it to a new organism or
    • translpant to a diff area of the same organism for access to the blood
    • no longer works- we now know some glands rely on something else (nervous impulse ie) to produce hormones
  7. Gastrointestinal tract endocrine function
    parts of the stomach and small intestine make hormones that regulate digestion and eating, and and have some effect on the brain
  8. Central nervous system endocrine function
    • hypothalamus of the brain makes key hormones affecting many body parts and regulates the pituitary gland
    • the hormones from hyp are either released directly into the blood or into the blood via the pituitary gland
    • other parts of the brain release chemicals into the cerebral spinal fluid (formed from blood) or into extracellular fluid surrounding cells
    • the pineal gland (attached to brain like pituitary gland) makes melatonin- important in cercadian rythems of the body like sleep
  9. placenta endocrine function
    • only functions in pregnancy
    • makes hormones
  10. What is a hormone
    • a chemical message important in communication in the body
    • they serves as regulators of body functions
    • they usually stimulate something, but can inhibit something too
  11. First messenger
    • carries info for the body
    • endocrine gland makes and releases the hormone into a circulating fluid (usually blood) and it will cause a response specifically influencing the target cells
  12. target cell(s)
    • cell(s) that will respond to the hormone
    • they have a receptor that will bind to the hormone
  13. Example functions that hormones stimulate
    • growth
    • reproduction
    • homeostasis
  14. Nervous and endocrine communication similarities
    • both carry info and integrate and regulate body functions (ex- heart rate regulated by N.S. and hormones)
    • both systems can affect/influence eachother (neuroendocrinology)
  15. nervous and endocrine communication differences
    • N.S. involves neurotransmitters while endocrine involves hormones
    • Nervous impulses very fast (milliseconds) vs hormones which can take seconds to days for response
  16. Nervous impulse
    • electrical events in neurons which release neurotransmitters (chemical) at synapse which affects the post synaptic cells
    • neurotransmitter only affects cells at the synapse- it is not circulating blood so it is not affecting cells unless at the synapse- it has a direct affect
  17. Are all hormones released into the blood?
    • no
    • paracrine effect: a hormone affects nearby cells
    • autocrine effect: a hormone has an immediate affect on its own production
    • cryptocrine effect: a substance affects cells in a closed space near the cell production (like paracrine but in a self contained area)
  18. example of cryptocrine effect
    in cryptochridsm- tesosterone stimulates sperm production in semi tubes and androgen binding hormone keeps testosterone in contained space
  19. Types of hormones
    • polypeptide and protein hormones
    • steroid hormones
    • amino acid derived hormones
    • fatty acid derivatives
    • gaseous molecules
  20. Polypeptide and protein hormones
    • major type
    • ex- insulin, glucagon, antidiuretic, etc
    • typically hydrophillic and lipophobic
  21. synthesis and release of polypeptide and protein hormones
    • synthesized on rough ER then packaged by the golgi into vessicles (sacs)
    • they are stored in active form in these vesicles (called secretory vesicles)
    • they will eventually be released out of the cell by exocytosis
    • some of these hormones are glycoproteins (ex-fsh)- have a carbohydrate part attached to the peptide chain
  22. what happens when polypeptide and protein hormones are stimulated (release pattern)
    • the endocrine glands that make them will make more hormone and release the stored horomone
    • these hormones are not made on demand
  23. How are polypeptide and protein hormones first made?
    • often first synthesized as a larger molecule (a larger protein) and will undergo steps to become the active hormone
    • 1. pre-prohormone (large molecule) is synthesized then cleaved to make smaller prohormone
    • 2. prohormone cleaved again to form active hormone
    • the parts of the peptide not in the active hormone have no effect
  24. Steroid Hormones
    • made from cholesterol related biosynthetic pathways
    • hydrophobic and lipolytic (fat soluble)
    • Est. and test. are examples
    • released by cells through diffusion bc they can pass through the cell membrane
    • made on demand- not stored
  25. Amino Acid derived hormones
    • catecholamines (epinepherine ie) from adrenal gland and thyroid hormone
    • catecholamines are similar to protein hormones
  26. Fatty Acid derivative hormones
    • fat soluble but they are not steroids
    • made from fatty acids, not cholesterol
    • prostaglandins for ex. 
    • not stored
  27. prostaglandins
    • made from 20 carbon fatty acids- especially arachadonic acid
    • assist oxytocin in birth contractions
  28. Gaseous Molecules
    • have very specific synthesis
    • fast acting with short half life (inactivated quickly)
    • ie- nitrous oxide in erection function
  29. Release + transport of peptides and protein hormones
    • they are water soluble and blood is water based so they are soluble in the blood plasma
    • they travel free in the blood- not bound to something else to make it water soluble
    • even though it is not required some may be bound to plasma proteins in the blood (ie Albumin)
    • some may travel inside blood cells such as RBCs but mostly in plasma
  30. Release and transport of lipophillic hormones (Steroids)
    must be attached to plasma proteins (which are made in the liver and released into the blood) in the blood to keep soluble
  31. Release and transport of amino acid derived hormones
    catecholemines are like peptides, thyroid hormone is more complicated
  32. Hormone receptors
    • a target cell that responds to a hormone has a receptor(s) that recognizes the hormone and binds to it
    • receptors are always proteins
    • the recptor is either on the cell membrane (for water soluble hormones) or in the cytoplasm or nucleus (for lipid soluble hormones bc they can pass through the membrane)
  33. Signal induction
    the effect of a hormone on the target cell after the hormone binds to the receptor
  34. Do hormones only have one receptor?
    • no, one hormone may have a number of receptor subtypes, which can be tissue specific and allow different responses on targets
    • receptor subtypes often have different intracellular second messengers, which can cause different responses in target cells (all water soluble hormones have a second messenger)
  35. relationship between first and second messenger hormones
    • first binds to receptor and stimulates increase of secretion of second and the second will have an intracellular effect
    • it is common to use a second messenger- ie glucagon and parathyroid hormone use them
  36. What influence the effect of a hormone?
    • the concentration of the hormone
    • the number of receptors at the target cell
    • hormone's effect must be limited by disrupting the hormone/receptor interaction and inactivating the hormone to keep homeostatic balance
  37. Specific receptor types
    • protein, polypeptide, catecholamines (and some prostaglandins- lipid soluble) have recptors in the cell membrane when hormone does not enter target cell
    • steroid hormones have receptors inside the cell
  38. 2 types of protein polypeptiede receptors
    • enzyme coupled receptor (single or homodimer)
    • G protein coupled receptor (GPCR)
  39. enzyme coupled receptor
    • receptor with single strand spanning membrane
    • hormone binds to external domain
    • intracellular domain has intrinsic enzyme activity when hormone binds
    • enzyme phosphorylates specific amino acids in protien to ativate different intracellular pathways (ie- change membranes permeability, stimulate protein synthesis, etc)
    • basically- hormones dont enter the cell, they bind to the extracellular side of the receptors on the cell membrane and the intracellular domain has enzyme activity that occurs when binding happens and the enzyme in the cell phosphorylates specific amino acids to stimulate diff things
    • insulin binds and uses this to get glucose into the cells
  40. G-protein coupled receptor
    • more common for proteins and polypeptides to utilize
    • 7 transmembrane receptor group with 7 helicies spanning the cell membrane- has extracellular and intracellular domains
    • the hormone binds to the extracellular part of the receptor- the receptor is coupled with Gprotien 
    • the binding of the hormone to the receptor tiggers an intracellular transduction pathway  bc the Gprotein then activates an enzyme to form a second messenger- most commonly cyclase which will convert ATP to cyclic AMP and phosphates. 
    • the cyclic AMP then activates different proteins to trigger specific effects in the target cell
  41. what is an important protein activated by cyclic AMP?
    • protein kinase A
    • this enzyme phosphorylates other intracellular proteins like...
    • --> activated PKA passes through nuclear membrane and phosphorylates CREB which acts as a transcription factor to activate or supress genes (and by activating stimulating protein synthesis)
    • other important second messengers are involved in other specific actions (such as calcium for ex)
  42. Gprotien
    guanine nucleotide binding protein
  43. Steroid hormone receptors
    • located in the cytoplasm or nucleus of cells
    • steroids diffuse through membrane and bind to intracellular receptor to form the hormone-receptor complex
    • --> if the HR complex is in cytoplasm it will then enter the nucleus
    • HR complex acts as a transcription factor- binds to promoter site of target chromosome (usually histone protein) and stimulates transcription which stimulates translation causing protein synthesis (of membrane protein, enzyme etc) for cell response 
    • hydrocortosone, est, and test are examples of hormones that use this
  44. Difference between steroids and h2o soluble hormones paths (main idea)
    • steroids have a direct influence on the genome, where water soluble hormones use a second messenger path
    • although they have 2 diff paths, they can have the same effect- ie testosterone and growth hormone both stimulate growth but use 2 different mechanisms
  45. Factors influencing hormone secretion
    • level of something in the blood
    • -->feedback regulation
    • nervous impulse
  46. level of something in the blood- factors influencing hormone secretion
    • nutrient level (ie glucose, water, sodium, calcium)- purpose is for homeostasis of that substance
    • level of parameter (ie oxygen, pH, blood pressure)
    • level of another hormone (this can stimulate or inhibit a hormone)
  47. feedback regulation- factors influencing hormone secretion
    • when there are high levels you shut the hormone off- negative feedback- most common and critical for homeostasis
    • positive feedback not common in homeostasis because increases and increases until stopped by something physical, it is not kept in a balanced range
  48. Nervous impulse- factors influencing hormone secretion
    • total nervous control or partial control in addition to blood borne regulation 
    • feedback mechanisms may involve nerbous regulation
    • ex- epinepherine is totally controlled by the Nervous system
  49. 2 sections of the pituitary gland
    • adenohypophysis
    • neurohypophysis 
    • both parts have endocrine function
  50. adenohypophysis structure
    epithelial in structure- epithelial cells (which are typical for endocrine glands)
  51. neurohypophysis structure
    neural- like nervous tissue
  52. hypothalamus
    • physically attached to and regulates the pituitary gland (they are physically and physiologically connected)
    • has endocrine function as well as nervous
  53. cells of the hypothalamus
    • neurons make neurotransmitters and some neurons make hormones (neurohormones) so the cells secrete both- therefore they are called neurosecretory cells
    • --> but they usually dont make both at the same time
  54. neuroendocrine cells
    • cells that translate nervous input into hormonal output
    • ex- cells in hypothalamus make oxytocin-nervous impulses received by these cells and they release hormones into the blood
  55. Areas where the hypothalamus has endocrine function
    • reproduction
    • growth
    • homeostasis of many different things
    • there is also nervous influence on hormones and hormone influence on the brain
  56. pars tuberalis
    surrounds infundibulum but has no endocrine function
  57. infundibulum
    the stock that attaches the pituitary gland to the brain
  58. median eminence
    • part of hypothalamus
    • vascular- contains the portal blood
  59. pars distalis
    • anterior lobe of pituitary
    • aka adenohypophysis
  60. pars intermedia
    • structurally part of adenohypophysis
    • epethelial but sticks to posterior lobe in development
    • makes a hormone important in lower invertebrates skins for changing color
  61. pars nervousa
    • posterior lobe 
    • aka neurohypophysis
  62. Hypothalamic adenohypophyseal axis
    • specific nuclei or centers in the hypothalamus make hormones in neurons that extend to the median eminence 
    • from the median eminence there is a portal blood system which is direct blood vessels from the M.E. to the anterior lobe of the pituitary gland (direct blood connection)
    • see pic in notes if confused
  63. hypothalamic-neurohypophyseal axis
    • a direct neuro connection- neurons in the hyp make hormones which travel in neurons to the post pituitary and from there they are released into the blood
    • see pic in notes if confused
  64. Embryological development of pituitary gland
    • neurohypophysis develops as an outpocket of the hypothalamus and therefore is neural tissue
    • adnohypophysis differentiates from rathke's patch (an outgrowth from the roof of the mouth), therefore it is epithelial tissue
    • neural tissue grows downward, epithelial tissue grows upward and they fuse
  65. functions of hypothalamus
    • receives nervous input from many different sources: ex all types of senses, limbic system (emotion/memory), + higher centers in cerebrum
    • regulates many functions: ie internal organs through autonomic ns, pituitary gland, sends impulses up to higher centers in cerebrum, etc
  66. Hormone release of hypothalamic hormones
    • they have a pulsatine release: release in spurts (rather than a continuous release)- important for function
    • hormones are made in specific areas called nuclei
  67. examples of nuclei
    • paraventricular nucleus: makes oxytocin mostly and a little antidiuretic hormone
    • supraoptic nucleus: makes antidiuretic hormone and a little oxytocin
    • both oxytocin and ADH will travel via neuron to the posterior pituitary
    • other nuclei make hormones that either stimulate production/secretion ant. pit hormones or inhibit them
  68. types of anterior pituitary cells and the hormones they make
    • lactotrophs: prolactin
    • thyrotrophs: thyrotrophin (aka Thyroid stimulating hormone)
    • corticotrophs: corticotrophin (aka adrenocorticotrophic hormone ACTH)
    • gonadotrophs: FSH +LH
    • somatotrophs: somatotrophin (aka growth hormone)
  69. tropic/trophic
    this name indicates a stimulating hormone
  70. how are hormones named? give meaning for each hormone
    • after their target tissue usually
    • prolactin: breasts
    • TSH: thyroid gland
    • ACTH: adrenal cortex
    • FSH/LH: gonads
    • growth hormone: body in general, esp liver
  71. how is prolactin different from the rest of the ant. pit hormones
    • it is affected by dopamine- a neurotransmitter- but acts like a hormone here
    • dopamine is a catecholamine made from amino acid tyrosine and it inhibits the lactotrophs and therefore is a prolactin inhibiting hormone
    • primary regulation of prolactin is inhibitory unlike others, this inhibition will be overridden with stimulation when needed
    • prolactin the only hypothalamic hormone that is not a peptide
    • most other hypothalamic hormones act via the cyclic AMP mechanism
  72. hypothalamic hormone effects on ant. pituitary
    • TSH releasing hormone aka thyrotrophin releasing hormone: stimulates release of TSH
    • corticotrophin releasing hormone: stimulates corticotrophs to make ACTH
    • gonadotrophin releasing hormone: stimulates gonadotrophs to release both FSH and LH
    • growth hormone releasing hormone: stimulates somatotrophs to make GH
    • somatostatin (aka gh inhibiting hormone): inhibits the somatotrophs
  73. Adenohypophyseal hormones characteristics
    they are peptides, proteins, and glycoproteins
  74. intermediate lobe of pituitary gland
    • makes melanocyte stimulating hormone (MSH)- important in non human vertebrates for skin and fur color
    • human skin color is due to genetics, but this is important in human disorders- ACTH has some MSH activity if it is in excess; it can bind to MSH receptors causing skin color changes
  75. Growth hormone
    • a 191 single amino acid chain protein
    • has similarities to prolactin
    • secreted in pulses because of the stimulation from the hypothalamus (both GH releasing hormone and somatistatin are released in pulses)
    • there are times of day/situation where you will make more GH than others
    • liver makes insulin like growth factor- mediates some of GH's effects (only structurally like insulin, not functionally)
  76. situations where the level of GH you make will be altered
    • if fasting: increase in frequency of pulses and increase response to stimuli
    • at puberty: there is the highest pulse amplitude and GH level
    • as you age: level and amplitude decrease
  77. Where are GH receptors located?
    in most tissues, but specifically high levels of them in the liver
  78. ILGF
    • Insulin like growth factor
    • made in liver 
    • structurally like insulin, mediates some of GH's effects
  79. Main functions of growth hormone
    • stimulates growth from birth to puberty
    • functions in metabolism
  80. growth hormone stimulating growth from birth to puberty
    • in cell proliferation (making more and more cells): GH is synergistic with thyroid hormone and the sex steroid hormones that produce growth (they enhance eachother)
    • stimulates growth in cartilage of bone before it becomes hard
    • affects muscle: increases muscle mass and other soft tissue
  81. growth hormone function in metabolism
    • it is a hyperglycemic hormone (incr. blood glucose, esp when you aren't eating)
    • in your daily rythem, its higher when you sleep and lower when your awake and eating
    • stimulates the liver for gluconeogenysis (glucose synthesis from amino acids and glycerol from fat/synthesis of glucose from a non carbohydrate)
    • an insulin antagonist b/c insulin has the opposite function
  82. other functions of GH
    • promotes a lean body mass
    • has some effects similar to prolactin
    • has a positive effect on sense of well being
    • in reproduction it is synergistic with sex hormones in the growth spurt and in development of secondary sex strucutres, development of reproductive organs, and development of secondary sex characteristics
    • in the immune system it stimulates the synthesis of T an B synthesis
  83. how does GH promote a lean body mass?
    it is lipolytic so it promotes fat mobilization from the adipose tissue and stimulates fat breakdownstimulates protein synthesis (translation) fro growth and maintenance of tissues- esp skeleton, muscle and liver
  84. Disorders: if you make excess GH
    • make excess from a tumor as a child: gigantism- the person will grow 6-8 ft in height
    • make excess as an adult: acromegaly- overgrowth and widening of some bones (jaw, fingers, etc)
  85. Disorders: if you make too little GH
    • in a child: dwarfism- the cells arent making enough GH
    • in an adult: tired, metabolic changes (uaually not a tumor just body having less protein synthesis, making less gH, etc)
  86. laron dwarfism
    • a genetic disorder where people lack gh receptors
    • here treatment by administering GH would not work
  87. Prolactin
    • single 199 amino acid proten
    • some similiarities to GH
  88. main target of prolactin
    mammary glands of breasts
  89. functions of prolactin
    • stimulates milk production in the mammary gland cells (main function)
    • causes increase in glucose utilization increased protein synthesis and increased fat synthesis
    • stimulates breast development in pregnancy and keeps them developed in lactation
    • in men an women prolactin has a subtle stimulation of lymphoid tissue and immune function (primarily by stimulating T lymphocyte production)
  90. stimulus of prolactin
    nursing of baby on breast gives nervous stimulus that will override the inhibitory hormone control
  91. prolactin reactions/relations to other hormones
    • in development, prolactin is synergistic with other hormones (estrogen, progesterone, GH, etc) but you do not have milk production in pregnancy because high levels of est and progest from placenta inhibit it
    • oral contraceptives can also prevent milk formation in women nursing bc they have est and proget
    • prolactin inhibits FSH and LH in women- during lactation, for a certain amount of time there will be no ovulation (bc FSH and LH are very low) (ovulation needs FSH, LH, P, and E)- acts as natural birth control
  92. high prolactin
    • hyperprolactinemia (high prolactin in blood)
    • women: galactorrhea (milk release) esp in estrogen primed (developed) breasts; amenorrhea (lack of menstration), low gonadotropin releasing hormone
    • men: gynecomastia (breast hypertrophy)possible milk production; low testosterone, loss of libido (Bc gonadotropin releasing hormone is inhibited)
    • high PL inhibits other reproductive hormones
  93. treating high prolactin
    • there is a type of infertility where women dont ovulate bc they have high PL- treated with an antagonist which mimics the dopamine inhibiting it
    • the dopamine agaonist mimics it and cuases PL inhibition
  94. Glycoproteins
    FSH, LH and TSH
  95. Gonadotrophs
    • FSH and LH
    • affect men and women, targeting testes/ovaries
  96. FSH in the male
    • targets/affects the part of the testes that makes sperm (semineferous tubules)
    • stimulates spermatogenesis along with testosterone production
    • stimulates androgen binding hormone (a male sex hormone- main one is testosterone) which is made by sertoli cells in semi tubes; it binds testosterone and keeps it in the semi tubes
    • stimulates production of inhibin (important in feedback on FSH production) also made in sertoli cells
  97. LH in the male
    targets and stimulates interstitial cells in the testes to make testosterone
  98. FSH in the female
    • stimulates the ovarian follicles- their development, the release of the oocyte at ovulation (does this with the help of LH, E and P)
    • before ovulation, follicle cells make mostly E and some P, FSH stimulates inhibin from the follicle cells which is important in feedback
    • vital before ovulation
  99. LH in women
    although it does help stimulate ovulation, after ovulation it will stimulate the formation of the corpus luteum from follicle cells and stimulates production of hormones from the corpus luteum (mostly p and some e)
  100. Thyroid Stimulating Hormone (TSH)
    • similar function to ACTH, but has a different target gland
    • targets the follicle cells of the thyroid gland (these cells make thyroid hormone)
    • increases overall activity of thyroid gland (increases cell growth and organ growth, increased o2 consumption and glucose utilization)
    • increases iodine uptake into thyroid and iodine use in thyroid hormone synthesis and storage
    • increases thyroid hormone release into blood
  101. Adrenocorticotrophic Hormone (ACTH)
    • a 39 single chain amino acid polypeptide
    • made from a larger molecule called proopiomelanocortin
    • targets Adrenal gland cortex which synthesizes hydrocortisone (cortisol)
  102. ACTH functions
    • increases growth of adrenal cortex
    • increases blood flow in the cortex
    • increases synthesis and secretion of hydrocortisone
  103. Disorders: excess ACTH
    • on excess ACTH can bind to melanocyte stimulating hormone receptors which increases pigmentation of skin in cushings disease
    • cushings disease: high hydrocortisone levels, feedback doesn't work properly- has weight gain with fat deposit on face, between scapulae, abdomen, red striae (stretch marks) on abdomen, thin skin with ppor wound healing, muscle weakness
  104. cushings syndrome vs cushings disease
    • cushings disease caused by a pituitary tumor while cushings syndrome can be caused by side effects of hydrocortisol administered for another problem
    • cushings syndrome caused by high glucocorticoid
  105. Disorders: high TSH
    hyperthyroidism (excess thyroid hormone)
  106. Neurohypophysis (posteriors lobe) hormones
    • antidiuretic hormone and oxytocin (both 9 amino acid peptide chains)
    • --> both 1st made as much larger preprohormones and neurophysin (non endocrine parts) will be cleaved
    • hormones made by hypothalamus in magnocellular neurons and travel by neuron from hyp to post pit where they are secreted into blood
  107. Antidiuretic Hormone synthesis and storage
    • primarily supraoptic nuclei make it
    • accumulates in the herring bodies (neuurosecretory cells- represents the terminal end of the axons from the hypothalamus) of the axon and the axon terminal
  108. what is required for ADH release
    ca 2+ must enter the neuronal ending for release
  109. receptors of oxytocin and adh
    • they are peptides so receptors are on the cell membrane
    • ADH has at least 3 forms of G coupled receptors on the membrane (relates to different ADH functions)- different secondary messengers
    • even though oxytocin has more than one function, it only has one receptor form
  110. ADH
    • "against diuresis"- against urine production
    • decreases H2O excretion in the urine by retaining it in the blood 
    • aka: vasopressin ("blood vessel pressure")- bc it has a pressor effect to increase blood pressure under specific cercumstances
  111. antidiuretic effect of ADH
    • main function, critical for water balance in the body
    • ADH acts on kideny and stimulates H2O reabsorption from the kidney tubules (esp collecting tube) and retains the water in the blood in the kidney blood vessels
    • prevents H2O excretion in urine (urine will be more concentrated in solute)
  112. main stimulus for ADH antidiuretic effect
    • an increase in the osmolarity of the extracellular fluid in the hypothalamus (low water high salt)
    • if this continues, dehydration can occur
    • osmoreceptors sense the osmolarity in the plasma of the hyp
    • effect is to increase adh in hyp which goes to post pit then to the kidney where it will increase the permeability of the tubular cell membrane, it moves the aquaporins (protiens0 forming water channels allowing an increase of h2o to flow out of the tubules into the blood capillaries (this happens to maintain h2o homeostasis)
    • ADH will also stimulate thirst centers in the hyp to bring in more H2O (diff receptor)
  113. Drugs that affect ADH
    • Certain types of anesthetics increase ADH (decreasing urine production)
    • caffeine, alcohol, some diuretics used in high blood pressure therapy will inhbit ADH increasing urine outputs and increasing water loss from the body
  114. vasopressin effect of ADH
    • occurs in extreme situations (ie hemorrhage- blood loss)
    • stimulates constriction of blood vessels to keep blood in vessels and decrease blood loss
  115. stimulus for vasopressin effect of adh
    • decrease in bp due to loss of blood
    • sensed by baroreceptors located in part of the carotid artery sinus (widened part) and part of the aorta
    • medulla oblongata receives info by nerves and has a vasomotor center (controls muscle of blood vessels) and impulses then go to hyp to stimulate increase of adh which will circulate and cause constriction of blood vessels
  116. Disorders: excess adh
    • syndrome of inappropriate ADH hypersecretion (rare)- excess h2o reabsorption into blood, highly concentrated urine
    • hyponatremia- low sodium concentration in plasma, very dilute
  117. Disorders: lack of adh
    • you cant reabsorb a lot of h2o back into the blood so excess urination
    • diabetes insipidus- large volume of tasteless urine (cells take up glucose bc insulin works here, vs diabetes mellatus which would have very sugary urine)
    • polyuria- high volume dilute urine
    • polydipsia- excess thirst due to water loss
    • treatment- nasal ADHA analogue (a pill would be lost in digestion)
  118. Disorders: defective adh receptor
    • nephrogenid diabetes insipidous- failure to respond to ADH- very rare
    • treatment- drug decreasing kidney output of urine
  119. Oxytocin
    important in partuition (birth) and lactation
  120. oxytocin in partuition
    • stimulates tetanic (strong sustained) contractions of the uterus
    • smooth muscle of uterus becomes more sensitive to oxy as the body approaches birth and esp after labor begins
    • works with estrogen and prostaglandins for birth
  121. nervous stimulus for oxytocin in parturition
    once labor has begun (estrogen has started mild contractions), impulses will go from the uterus to the hyp to make oxy which goes to the post pit then blood- it will cause strong contractions and expulsion of fetus and the release of the placenta and fetal membranes (afterbirth) when birth is over and contraction of uterus to involute it back to pre-pregnancy size
  122. oxytocin in lactation
    • causes milk ejection (letdown) from breasts
    • stimulates contraction of myoepithelial cells around the glandular cells of the mammary glands in the breasts, these glandular cells make the milk and the myoepithelial cells contract causing release of milk from glandular cells into duct and out nipple
    • it is a neuroendocrine reflex (nervous stimulus and hormonal response)
  123. nervous stimulus for oxytocin in lactation
    • baby nursing-sends nervous impulses to brain and hyp for increase of oxytocin to post pit then circulating to the breasts for milk release
    • nursing also stimulates prolactin-impulses to hyp will inhibit the prolactin inhibiting hormone (dopamine) allowing prolactin to be made by ant pit
  124. Other effects of oxytocin
    • has a known effect on the brain- thought to have an influence on social and maternal behavior- bonding and protecting of infants
    • oxy thought to have an antianxiety effect in men and women
    • in men there is a possible role in stimulating ejaculation and testoerone production
  125. disorders: oxytocin deficiency
    • birth does not progress- started by est but contractions not strong enough and cannot progress- induction by pitocin (synthetic oxytocin- prevents a c-section)
    • inability to lactate
Card Set
Introduction Hypothalamus and Pituitary Gland- Exam I
Exam of 09/23/2015