HTHS Mod 14

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  1. In order to maintain homeostasis, what two main systems of the body are responsible for the task of continually receiving, interpreting, and responding to stimuli?
    • The nervous system and endocrine systems -  coordinate all body systems
    • Controlled by mediator molecules
    • Nervous: neurotransmitters
    • Endocrine: hormones
  2. hormone
    • a mediator molecule secreted from one part of the body that circulates via the body fluids to influence cells in another part of the body
    • Typically, secreted into interstitial fluid, then bloodstream till it finds target cell
  3. The endocrine system
    • made up of primary & secondary endocrine organs 
    • Primary consists of the pituitary, thyroid, parathyroid, adrenal and pineal glands (meaning their primary function is endocrine)
    • Secondary are other organs that secrete hormones, but they are not exclusively endocrine glands
    • Together with nervous system, coordinate vital body functions to maintain homeostasis
  4. What are the secondary endocrine organs?
    • Hypothalamus, thymus, pancreas, ovaries, testes, kidneys, stomach, liver, small intestine, skin, heart, and placenta
    • They have endocrine functions and other functions as well. So not strictly endocrine
  5. What function do hormones have
    • control of composition and voume of internal environment
    • regulate metabolism and energy balance
    • contraction of smooth and cardiac muscle fibers
    • influence glandular secretions
    • Integration of growth and development
    • reproductive control
    • regulation of sleep-wake cycles
    • emergency control during physical & mental stress like trauma, starvation, hemorrhage
  6. recall difference btwn exocrine and endocrine
    • Exocrine is secreting products of cells through a duct (tube)
    • Endocrine is secreting into fluids
  7. Control mechanisms of nervous system
    • Use neurotransmitters, which are released locally across a synapse
    • Targets muscle cells, glands and other neurons
    • Onset of action is Milliseconds
    • Action duration is also Milliseconds
  8. Control mechanisms of endocrine systems
    • Use hormones; responses are usually distant from the site of release
    • Targets cells throughout body; bind to receptors in or on target cells
    • Onset of action: Seconds to hours to days
    • Action duration: generally longer
  9. Hormone receptors
    • Are simply cellular proteins
    • The presence/absence/number of hormone receptors that dictate action of a hormone
    • Likewise, Target cells can dictate # of receptors available to bind hormone. They can:
    • Up-regulation: increased responsiveness by increasing receptor #'s
    • Down-regulation: decreased responsiveness by decreasing receptor #'s
    • *therefore,
  10. circulating hormones
    hormones secreted into the interstitial fluid and then into the blood stream, giving them access to the entire body
  11. paracrines
    Hormones secreted into the interstitial fluid that act on neighboring cells
  12. Autocrines
    • Hormones secreted into the interstitial fluid that act on the same cell that secreted it
    • therefore the cell can act on itself
    • Cancer cells have this ability
  13. What is one of the main classifications that separates different types of hormones?
    • based on their solubility in water or lipids
    • recall that a substance can more easily move into a cell if it is small, neutrally-charged OR lipid soluble
    • Lipid-soluble hormones or water-soluble hormones
  14. lipid-soluble hormones
    • can freely diffuse into a cell and bind directly to intracellular receptors
    • Include steroid hormones, thyroid hormones and nitric oxide
    • most of the available lipid-soluble hormone is carried in blood by transport proteins
  15. What is a "steroid"
    • isn't based on what molecule does, but simply on it's shape
    • Has a 4 ringed structure
  16. water-soluble hormones
    • freely circulate in the bloodstream; don't need carrier or to be attached to another molecule
    • can't pass through cell membrane; must bind to membrane receptors and initiate a change in the cell indirectly
  17. transport proteins
    • proteins which lipid-soluble hormones must bind to in the blood
    • By binding, the water solubility of the hormones is increased
    • also keep smaller lipid-soluble hormones from getting filters in the kidney and lost in urine
  18. Lipid-soluble hormone action: explain the process
    • Hormone diffuses into the cell through the lipid-bilayer
    • If it's the target cell, hormone can bind and create a receptor-hormone complex within the cytosol or nucleus
    • This complex can alter the gene expression by "turning" the genes encoded by the cell's DNA "on or off"
    • Therefore, depending on type of receptor hormone binds to, can be excitatory or inhibitory in that cell.
    • End result is the alteration of cell's activity
  19. catecholamines
    • "-amines" = functional group
    • "catecho-" = the ring, or structure, of the molecule
    • includes epinephrine, norepinephrine, and dopamine
  20. Examples of water-soluble hormones:
    • amines - epinephrine, norepinephrine, dopamine
    • peptides/proteins - insulin, parathyroid hormone
    • Eicosanoids - prostaglandins
  21. Water-soluble hormone action: explain process
    • The hormone (1st messenger) attaches to receptors on plasma membrane of target cell
    • Receptor-hormone complex activates a G Protein (like a cellular switch "on" or "off")
    • G protein activates adenylate cyclase
    • Adenylate cyclase converts ATP to cyclic AMP (cAMP) (2nd messenger) in the cytoplasm
    • cAMP activates enzymes (protein kinases) which bring about the desired effect within the cell (therefore, 2nd messenger can act as activators, inhibitors or cofactors)
    • Ca++ is also a common 2nd messenger
    • *recall story about student trying to get friend message, so uses another student to get message to friend in class
  22. Amines
    • water soluble hormones
    • include epinephrine, norepinephrine, dopamine
  23. Can Water-soluble hormone freely enter cell?
    • because of their limited lipid solubility, they can't freely enter cell
    • *recall story of student trying to get message to friend in class. Uses 2nd student to get message to them.
  24. Water-soluble hormone action: first 2 steps
    • 1- The hormone (first messenger) binds to receptor on cell membrane. By forming a receptor-hormone complex, a membrane protein (G protein) is activated.
    • The activation of the G protein will then activate the enzyme adenylate cyclase.
    • 2- Adenylate cyclase converts ATP into cyclic adenosine monophosphate (cAMP , which is second messenger)
  25. Water soluble hormone action: 3rd and 4th steps
    • 3. cAMP will activate one or more protein kinases 
    • *remember, kinases phosphorylate (add a phosphate to other molecules)
    • 4. In their case, phosphorylated molecules are proteins. Through phosphorylation, some proteins are activated and some are deactivated.
    • *There are many different types of kinases, so the effects can be numerous
  26. Water-soluble hormone action: last step
    • to limit the duration of the response, unless new hormone binds to the receptors, the enzyme phosphodiesterase inactivates cAMP
    • *Think phospho-"DIE"-sterase
  27. What other second messengers can there be for water-soluble hormone action
    include Ca++ ions and cGMP (cyclic guanosine monophosphate)
  28. Hormone secretion is signaled and regulated by what different mechanisms
    • signals from nervous system
    • chemical changes in blood
    • levels of other hormones
  29. What type of feedback system do most hormones work through?
    • Negative, few by positive
    • Negative feedback = hormone output reverses a particular stimulus
    • Positive feedback = hormone output encourages and reinforces the stimulus
    • *recall with any feedback system, there must be a receptor for stimulus, interpretation (control) center, and an initiated response
  30. What factors influence the responsiveness of a target cell to a hormone
    • The concentration of hormone
    • presence/absence/number of receptors available to bind hormone
    • influences of other hormones
  31. permissive effect
    When two hormones are required for desired action
  32. synergistic effect
    when two hormones dictate similar actions and work together to create an even more powerful result
  33. antagonistic effect
    • When two hormones oppose each other
    • ex: insulin/glucagon
  34. hypophysis
    • what the pituitary gland was formerly referred to
    • pea-shaped gland - anatomically & functionally connected to hypothalamus by the infundibulum
    • has two lobes: anterior and posterior
    • It's also commonly referred to as the "master glad"; but recall it is controlled by the hypothalamus
  35. hypothalamus
    • the major link btwn the nervous and endocrine systems: received input from several regions in brain
    • controls pituitary gland
    • *Produces regulating hormones that circulate to adenohypophysis and stimulate it to secrete it's own hormones
    • *sends nerve impulses to neurohypophysis which stimulate it to secrete oxytocin and ADH
  36. infundibulum
    a funnel-shaped stalk which connects the pituitary gland to the hypothalamus
  37. adenohypophysis
    • the anterior lobe of the pituitary
    • about 75% of pituitary weight - functionally connected to hypothalamus by blood vessels
    • The hypothalamus produces regulating hormones to circulate down to anterior lobe & stimulates lobe to secrete it's own hormones
    • *"Adeno-" means gland, so the relationship btwn hypothalamus and anterior pituitary is gland to gland
  38. neurohypophysis
    • the posterior pituitary, or second lobe
    • functionally connected to hypothalamus by specialized neurosecretory neurons
    • to stimulate neurohypophysis, the hypothalamus sends nerve impulses which stimulate it to secrete oxytocin and ADH
    • *Does not synthesize any hormones - hormones from this gland are produced by neurosecretory cells in hypothalamus and secreted down axons w vesicles to be stored and later released from posterior pituitary
    • *"neuro" refers to the connection btwn posterior lobe & hypothalamus-by neurons
  39. releasing hormones
    • hormones from the hypothalamus
    • stimulate the "release" of hormones from the adenohypophysis
    • *if releasing is in the name of the hormone, it came from the hypothalamus
  40. inhibiting hormones
    • hormones from the hypothalamus that inhibit the release of hormones from the adenohypophysis
    • *used if hypothalamus needs to suppress the action of pituitary
  41. tropic hormone
    • hormones from adenohypophysis that act on other endocrine glands
    • *released from one endocrine gland and targets another
  42. "7 hormones of the adenohypophysis
    • hGH = Human growth hormone
    • TSH = Thyroid stimulating hormone
    • ACTH = Adrenocorticotropic hormone
    • FSH = Follicle stimulating hormone
    • LH = Lutenizing hormone
    • PRL = Prolactin
    • MSH = Melanocyte-stimulating hormone
  43. hGH
    • human growth hormone 
    • stimulated growth of body cells
    • Correlates with Growth hormone-releasing hormone (GHRH)
  44. TSH
    • Thyroid stimulating hormone
    • Stimulates thyroid gland
    • Correlates with thyrotropin-releasing hormone (TRH)
    • *thyrotropin = in - only one that has a c is the sex ones. So n is legs closed, c is legs open
  45. ACTH
    • Adrenocorticotropic hormone
    • Stimulates cortex of adrenal gland
    • Correlates with Corticotropin-releasing hormone (CRH)
    • *corticotropin = in - only one that has a c is the sex ones. So n is legs closed, c is legs open
  46. FSH
    • Follicle stimulating hormone
    • targets ova/sperm development and production
    • Correlates with Gonadotropic-releasing hormone (GnRH)
    • *Gonadotropic - ic = legs open.
  47. LH
    • Lutenizing hormone
    • Maturation of uterine lining, testosterone production, and ovulation
    • Correlates with gonadotropic-releasing hormone (GnRH)
  48. PRL
    • Prolactin
    • lactation of mammary glands
    • Correlates with prolactin-releasing hormone
    • (PRH)
  49. MSH
    • Melanocyte-stimulating hormone
    • Darkens melanocytes
    • Correlates with corticotropin-releasing hormone
    • (CRH)
    • *corticotropin - in - only one that has a c is the sex ones. So n is legs closed, c is legs open
  50. TRH
    • thyrotropin-releasing hormone
    • stimulates pituitary to release TSH
    • *thyrotropin - in - only one that has a c is the sex ones. So n is legs closed, c is legs open
  51. GHRH
    • growth hormone-releasing hormone
    • stimulates pituitary to release hGH
  52. CRH
    • Corticotropin-releasing hormone
    • stimulates pituitary to release ACTH & MSH
  53. GnRH
    • Gonadotropic-releasing hormone
    • Stimulates pituitary to release FSH & LH
  54. PRH
    • Prolactin-releasing hormone
    • stimulates pituitary to release prolactin
  55. Factors contributing to disorders of the endocrine system
    • having too much or too little (hypo/hypersecretion)
    • Can be other causes, but symptoms will be similar to hyper/hyposecretion:
    • Ex: insufficient receptors, 2nd messenger defects, faulty receptors, etc.
  56. Possibilities that can cause hyposecretion
    • too little hormone production
    • decreased hormone receptors
    • second messenger system defects
    • lack of hormone precursors
    • degraded hormones
    • ischemia
  57. ischemia
    poor blood flow
  58. possibilities that can cause hypersecretion
    • excessive hormone production
    • tumors of endocrine origin - causing excess hormone release. benign or malignant
    • Absence of normal feedback mechanisms
  59. Endocrine disorders of hGH secretion
    • pituitary dwarfism
    • giantism
    • acromegaly
  60. pituitary dwarfism
    • caused by hyposecretion of hGH during childhood
    • w/o hGH, epiphyseal plates will close before pt reaches mature level
    • deficient growth of tissue will affect all body systems; however child will have normal body proportions
    • *not only cause of dwarfism
  61. giantism
    • caused by hypersecretion of hGH during childhood (during pts growth phase)
    • overall body proportions will remain consistent, but pt will be very tall
    • main cause is tumor of anterior pituitary
    • detection and treatment have made giantism fairly rare
  62. acromegaly
    • a disorder caused by excessive hGH during adulthood
    • deals with increased density in bone and tissue
    • Enlargement and elongation of bones of the face, jaw, cheeks and hands, associated tissues can enlarge causing circulatory, nerve and skin probs. 
    • The long bones of the extremities are unaffected cause growth plates are already closed
    • Commonly causes arthritis and carpal tunnel syndrome due to excess tissue growth
  63. hypothalamic nuclei
    • the nuclei in the hypothalamus which synthesize hormones (oxytocin and ADH) to be sent to the posterior pituitary
    • Specifically: paraventricular and 
    • supraoptic nuclei
    • The axons from these nuclei make up hypothalamohypophyseal tract
  64. oxytocin
    • hormone made by paraventricular and supraoptic nuclei in hypothalamus
    • targets uterus and breasts after delivery of baby
    • In uterus, stimulates contractions THROUGH POSITIVE FEEDBACK
    • In breasts, stimulates milk "let down" in response to infant sucking
    • *The purpose in men and non-pregnant women is unclear, but thought to promote feelings of sexual pleasure during and after intercourse and encourages emotional bonding btwn mating pair. So some call it the "love hormone"
  65. vasopressin
    • ADH - antidiuretic hormone
    • hormone which decreases amount to urine the body produces
    • causes arterioles to constrict, thereby increasing blood pressure
    • targets ducts in kindey and sweat glands in skin to minimize water loss
  66. osmoreceptors
    found in the hypothalamus, monitor blood osmotic pressure (relates to concentration of blood)
  67. What happens with high blood osmotic pressure
    • The high pressure (meaning high concentrated blood) stimulates hypothalamic osmoreceptors; Which in turn activate the neurosecretory cells that synthesize and release ADH
    • Nerve impulses liberate ADH from axon terminals in posterior pituitary into bloodstream
    • PRINCIPAL RESULTS:
    • Kidneys retain more water, which decreases urine output
    • Sudoriferous (sweat) glands decrease water loss by perspiration
    • Arterioles constrict, increasing blood pressure
  68. What happens with low blood osmotic pressure?
    The low pressure (low concentration, or dilute) inhibits hypothalamic osmoreceptors, which reduces or stops ADH secretion
  69. What specific target tissues does ADH act on?
    • kidneys - influencing the collecting tubules (ducts) to increase water reabsorption
    • sudoriferous (sweat) glands
    • smooth muscle cells of blood vessels - increased BP by constricting arterioles
  70. diabetes insipidus
    • most common condition related to ADH
    • Two physiological types:
    • *Either form has same effect: pt will not reabsorb water and therefore secrete large volumes of very dilute urine - from 1-1.5 liters (normal) to >2.5+ per day
  71. Two types of diabetes insipidus
    • neurogenic = insufficient production or secretion of ADH
    • nephrogenic = diminished renal response to ADH that was produced
  72. diabetes insipidus vs diabetes mellitus
    • *"insipidus" = tasteless - urine is very dilute
    • "mellatis" = sweet - urine is sweet
  73. thyroid gland
    • has two lateral lobes, connected in middle by "isthmus" bridge
    • sores 100-day supply of secretory products
    • located inferior to larynx, specifically the thyroid cartilage (adams apple)
    • butterfly shaped
    • thyroid follicles make up most of gland, they secrete 2 hormones: T4 & T3
  74. thyroid follicle
    • small spherical sacs which make up the thyroid
    • main functional unit of thyroid gland
    • each follicle consists of a central lumen, surrounded by wall of follicular cells (these cells change shape when stimulated to produce hormone)
    • Secrete 2 hormones: T3 & T4
  75. TGB
    • Thyroglobulin ~ is a protein synthesized inside thyroids follicular cells (bordering cells)
    • consists of approx 5000 amino acids, which more than 100 are the amino acid tyrosine
    • *"bin" - making Thyroid hormone from ingredients in the bin
  76. C cells
    • also called parafollicular cells
    • a scattered group of cells surrounding each follicle
    • *on the outside of each follicle - so in betwn follicles
  77. How is T3 & T4 made from TGB
    • to synthesize the thyroid hormones, TGB is released into the lumen of thyroid follicles
    • Within TGB, 1 or 2 iodine atoms attach to each tyrosine molecule
    • The tyrosine molecules then link to form thyroid hormone, containing either 3 or 4 atoms of iodine
  78. So how are the thyroid hormones synthesized and put into circulation?
    • When needed, TGB moves into follicular cells, and digestive enzymes cleave T3 and T4 from the TGB molecule
    • T3 and T4 are lipid soluble, so they can diffuse through the plasma membrane and bind to the carrier protein thyroxin-binding globulin (TBG) in the blood
  79. T4
    • thyroxin (tetraiodothyronine)
    • (tetra = 4)
    • T4, hormone secreted by thyroid
    • *prefix describes # of iodine molecules
  80. T3
    • Triiodothyronine
    • *prefix describes # of iodine molecules
  81. What stimulates the hypothalamus to secrete TRH & Whats the result
    • TRH = thyrotropin-releasing hormone
    • low T3 and T4 levels OR low metabolic rate stimulates release of TRH
    • this results in the anterior pituitary producing TSH (thyroid-stimulating hormone) which is released into the blood and binds to TSH receptors in follicular cells, stimulating secretion of T3 & T4 into blood
    • Elevated T3 inhibits release of TRH and TSH (negative feedback)
    • *Most of the T4 released is converted to the more potent T3
  82. Required steps for T3 & T4 synthesis
    • Iodine trapping
    • Synthesis of TBG
    • Oxidation of iodide
    • Iodination of tyrosine
    • Coupling of T1 and T2 to make T3 and T4
    • Pinocytosis and digestion of colloid
    • Secretion of thyroid hormones
    • Transport of T3 and T4 in the blood
  83. Iodine trapping
    • First required step in T3 & T4 synthesis
    • Iodine circulates in blood as iodide ( I- )
    • Iodide is actively transported into the follicular cells
    • Because of this process the thyroid gland contains most of the iodide in body
  84. synthesis of TGB
    • TGB (thyroglobulin) is a glycoprotein produced by follicular cells
    • it contains large numbers of the amino acid tyrosine
    • Tyrosine is the site on the TGB molecule that will bind with iodine
  85. Oxidation of iodide
    Before iodide can bind to tyrosine, it must be oxidized and combine with another iodide to form an iodine molecule ( I2 )
  86. Iodination of tyrosine
    The side chain of tyrosine may pick up one (T1) or two (T2) iodine molecules
  87. Coupling of T1 and T2 to make T3 and T4
    As one of the last steps, two tyrosine molecules are joined to form either T3 (T1+ T2) or T4 ( T2 + T2)
  88. Pinocytosis and digestion of colloid
    Once synthesized, the iodine-containing TGB reenters the follicular cells and digestive enzymes break down the molecule, releasing the formed T3 and T4
  89. Secretion of thyroid hormones
    T3 and T4 are lipid soluble, so they freely pass the cell membrane into the interstitial fluid and into the blood
  90. Transport of T3 and T4 in the blood
    • Once in bloodstream, 99% of secreted hormone binds to transport proteins, mainly TBG (thyroxine-binding globulin)
    • NOT TO BE CONFUSED WITH TGB

    *most body cells have receptors for T3 & T4, so the actions are quite broad
  91. Thyroid hormone actions:
    • regulate oxygen use
    • increase basal metabolic rate
    • increase protein synthesis 
    • increase carb and fatty acid catabolism
    • increase reactivity of nervous system by increasing sensitivity to epinephrine and norepinephrine
    • Control tissue growth and development along with hGH
  92. importance of thyroid hormone: increasing BMR
    • BMR = basal metabolic rate 
    • the rate of oxygen consumption while awake, at rest and fasting. 
    • When need for ATP increases, use of all nutrients increases
  93. importance of thyroid hormone: stimulating synthesis of additional sodium-potassium pumps
    • Is a major action with a cascade of effects
    • With the increase in the Na/K pumps, the demand for ATP is greater
    • At ATP is produced, calories are used, and more heat is produced (exothermic)
    • This is how thyroid hormones help a person regulate their normal body temp
  94. importance of thyroid hormone:
    *increasing protein synthesis
    *increasing fatty acid & glucose catabolism
    *decreasing blood cholesterol
    • Increasing protein synthesis encourages growth
    • Fatty acids and glucose are used to synthesize ATP
    • Reduces blood cholesterol by increasing cholesterol excretion
  95. importance of thryoid hormone: 
    *increasing the effects of nor/epinephrine
    *Accelerating body growth
    • Increasing efforts of epinephrine/norepinephrine enhances the sympathetic nervous response (heart rate, force of heart contraction, and BP)
    • Accelerating body growth, especially during fetal life and adolescence, by working synergistically w hGH and insulin to develop the skeletal and nervous systems
  96. goiter
    • an enlargement of the thyroid
    • found in pts with hypothyroidism, hyperthyroidism, and euthyroidism (normal thyroid function)
    • *In many countries, goiter is due to iodine deficiency. Rare in US cause of "iodized" salt
  97. What happens with hypothyroidism
    • low basal metabolic rate
    • cold intolerant
    • constipation
    • decreased respiratory rate
    • bradycardia
    • weight gain
    • lethargic
  98. What happens with hyperthyroidism
    • hight basal metabolic rate
    • heat intolerant
    • diarrhea
    • increased respiratory rate
    • tachycardia
    • weight loss
    • anxious
  99. Congenital hypothryoidism
    • hypothyroid disorder with occurs in childhood
    • formerly called cretinism (= idiot-ism)
    • In addition to common hypothyroidism, pt demonstrates low growth rate (dwarfism) & mental retardation, due to the  decreased synergistic relationship btwn thyroid hormones and hGH.
    • Result is decrease in development of nervous and skeletal systems
    • "congenital" = your born w it
    • can be treated
  100. Myxedema
    • hypothyroid disorder which occurs in adulthood
    • insufficient thyroxin
    • has similar symptoms to congenital hypothyroidism, w/o CNS & skeletal issues
    • Pts aren't mentally retarded but do show some diminished intelligence
    • pts gain weight easily
    • have abnormal "edema"
  101. Graves disease
    • most common form of hyperthyroidism
    • autoimmune disease resulting in excess thyroid hormone secretion due to the production of antibodies that act like TSH
    • Peculiar trait is exophthalmos, which is a condition that causes the eyes to protrude or bulge
    • *the antibodies act as "Ghosts" robbing a grave
  102. What controls our calcium levels & what do we use it for?
    • Thyroid - C Cells (parafollicular cells) AND
    • Parathyroid - Parathyroid hormone
    • Stored in bone matrix, need a little in blood/extracellular space for blood clot & muscle contraction
  103. thyrocalcitonin
    • more commonly called calcitonin
    • produced by C cells in the thyroid
    • high blood calcium stimulates C cells to secrete calcitonin
    • decreases calcium by:
    • decreasing action of osteoclasts (thereby promoting calcium & phosphate storage in bone matrix)
    • decreases amount absorbed by GI tract
    • increase amount of calcium in urine
    • ** think calci-TONE-in; tone DOWN calcium levels
  104. parathyroid glands
    • small, round masses of tissue attached to the posterior surface of the lateral lobes of thyroid
    • Typically there are 4: two parathyroid glands attached to each lobe (one superior and one inferior)
    • contain chief (principal) cells which produce and secrete PTH
  105. Actions of PTH
    • parathyroid hormone
    • Stimulated when blood calcium levels are LOW; brings it up by:
    • Stimulating osteoclastic activity
    • increases levels of calcitriol (active form of Vit D) in GI tract
    • Decreasing amount of calcium lost in urine
    • also decreases blood phosphate levels
    • *think of "para" - for = lets get calcium for our neighbors and friends
  106. Compare the actions of the parathyroid hormone and calcitonin
    • they are antagonists
    • PTH's goal is to increase blood calcium levels
    • Calcitonin wants to lower calcium levels
    • This is how the body maintains normal calcium, phosphate, and magnesium homeostasis
    • *Parathyroid hormone vs. calcitonin made in the Parafollicular cells
  107. Adrenal Glands
    • Two total: each located superior to each kidneys
    • two regions: the adrenal cortex and the adrenal medulla
    • Produce steroid hormones that regulate glucose and electrolyte levels
  108. adrenal medulla
    • the innermost region of adrenal glands
    • Secretes epinephrine and some norepinephrine
    • Innervated & controlled by sympathetic preganglionics
    • Acts similar to a sympathetic postganglionic neuron; secretes "-pinephrine" as hormone (instead of neurotransmitter)
    • Job is to duplicate and prolong the sympathetic response
    • Contain chromaffin cells
  109. What is the effect of the adrenal medulla releasing epinephrine/norepinephrine as a HORMONE (instead of neurotransmitter; as the medulla tends to act sympathetic postganglionic)
    • similar to sympathetic effects;
    • slower onset but last longer
  110. chromaffin cells
    • of the medulla
    • controlled by sympathetic preganglionic neurons from CNS
    • This is why medullary response is very fast
  111. Adrenal cortex
    • of the adrenal glands
    • has 3 functional zones: zona glomerulosa, zona fasciculata, zona reticularis
    • produce the "cortical" hormones
  112. zona glomerulosa
    • most superficial zone of the adrenal cortex
    • secretes mineralocorticoids
    • *"The earth is Gloreous" - live on top, made of minerals
  113. mineralocorticoids
    • a cortical hormone secreted by the zona glomerulosa
    • help control water and electrolyte (Na+ and K+) balance 
    • *Job is to keep blood volume and BP homeostasis
    • Aldosterone is main mineralocorticoid
    • "mineral" = controls minerals; "corticoids" = comes from cortex
  114. aldosterone
    • plays largest role of mineralocorticoids
    • Job is to raise blood volume & BP
    • Conserves Na+ & H2O through reabsorption in kidneys
    • Promotes the excretion of H+ and K+  from kidneys into urine
    • *the increased water reabsorption results in blood volume and BP increase
    • *"Where's Aldo?" - earth needs water
    • Controlled by RAAS
  115. zona fasciculata
    • middle zone of adrenal cortex
    • secretes glucocorticoids
    • *you stuff your Face with Glucose suger behind a mask
  116. glucocorticoids
    • secreted from the zona fasciculata of the adrenal cortex
    • primary glucocorticoid is cortisol
    • functions to regulate glucose availability and metabolism
    • "gluco-" = controlling glucose; "corticoids" = from cortex
    • *because of sugar, you need cortisol diet
  117. zona reticularies
    • most deep zone of adrenal cortex
    • produces and secretes gonadocorticoids;
    • *basements are rectangular, and that's the bedrooms are for sex
  118. gonadocorticoids
    • weak androgens
    • small amounts are secreted in both male and females
    • In males, converted to testosterone
    • In females, converted to testosterone and finally estrogen (also contribute to libido)
  119. androgens
    • masculinizing steroid hormones from adrenal cortex
    • contribute to development of secondary sex characteristics
  120. What is the sequence for release of "cortical" hormones?
    • Hypothalamus secretes CRH (Corticotropin-releasing hormone)
    • This stimulates the pituitary to release ACTH
    • This, in turn, stimulates release of the "cortical" hormones
  121. RAAS
    • Renin-angiotensin-aldosterone system
    • controls the secretion of aldosterone - whose job is to raise Blood volume & BP
    • Stimulated by decrease in BP by all or one:
    • decrease in blood volume
    • dehydration
    • Na+
    • Hemorrhage
    • (Notice they all cause loss in BP & blood volume)
  122. Basic summary of the process resulting in release of Aldosterone
    • Low BP stimulates juxtaglomerular cells in kidneys to secrete the enzyme renin
    • Renin circulates in blood & converts angiotensinogen into angiotensin I
    • As angiotensin I circulates to lungs, the enzyme ACE converts angiotensin I to angiotensin II
  123. -ogen
    • refers to molecule that is not activated yet
    • When activated, becomes a biologically active molecule
  124. renin
    • secreted by juxtaglomerular cells in the kidney; which are stimulated by low BP
    • This circulates in the blood and converts angiotensinogen into angiotensin I
  125. angiotensinogen
    • a plasma protein produced in the liver
    • *-ogen = inactive
    • converted into angiotensin I by the enzyme renin
  126. Angiotensin I
    circulates in blood till it comes into contact with an enzyme in the lungs called ACE

    then it is converted into angiotensin II
  127. ACE
    • angiotensin-converting enzyme
    • when it comes into contact with angiotensin I, it converts it into angiotensin II
  128. angiotensin II
    • has 2 main actions to increase blood pressure :
    • stimulates vasoconstriction
    • stimulates the release of aldosterone from adrenal cortex (which then circulates to kidneys
  129. cortisol
    • main glucocorticoid
    • is a person's anti-hypoglycemic hormone
    • will do whatever it can to keep glucose levels up; even if it means gluconeogenesis
    • *Main stress hormone 
  130. effects of cortisol
    • regulate metabolism
    • gluconeogenesis
    • anti-inflammatory effects
    • Resist stress (extremes)
  131. gluconeogenesis
    • the formation of new glucose
    • takes place when we haven't had any carbohydrates
    • Goes to other body sources to get nutrients & forms glucose-like-stuff 
    • does this by promoting breakdown of proteins (typically muscle) and triglycerides from adipose tissue to form glucose
  132. Anti-inflammatory effects of cortisol
    • very powerful anti-inflammatory
    • works by suppressing inflammation
    • *side effect is suppressing immune system
    • therefore, having high levels of cortisol lowers immune defense 
  133. Disorders of Adrenal cortex
    • Cushing disease/syndrome
    • addison disease
  134. disease vs syndrome
    • Disease relates to a certain CAUSE of a condition
    • Syndrome relates to a GROUP of symptoms that looks like the disease
    • *Ex: A person with Cushings syndrome has symptoms that look like Cushings disease; yet they don't have the disease, there is another reason for their symptoms
  135. Cushing disease/syndrome
    • Caused by hypersecretion of cortisol OR ACTH-secreting tumor causing excess of cortisol
    • Results: 
    • High blood glucose
    • Immune suppression and poor wound healing
    • High BP
    • Body fat redistribution = moon face, buffalo hump (fat pads on shoulders) and a hanging abdomen
    • *basically, body breaks down fats and redistributes it to the core of body. Big trunk, tiny extremities
    • **Cortisol is CRUSHING me w too much sugar and water!!
  136. Addison disease
    • Results from hyposecretion of cortisol and aldosterone
    • Caused by autoimmune destruction of adrenal cortex
    • Symptoms:
    • low blood glucose
    • Low Na+ 
    • high K+
    • Low BP
    • *your really wanting to "Add" sugar and water to Kool-aid, but you can't
  137. Pheochromocytoma
    • an adrenal medulla disorder involving a benign tumor of the chromaffin cells
    • results in hypersecretion of epinephrine & norepinephrine
    • Causes prolonged sympathetic fight or flight response:
    • high heart rate
    • high BP
    • increased metabolism (weight loss)
    • anxiety/nervousness
    • hyperglycemia
    • sweating and headaches
  138. Pancreas
    • Has both endocrine and exocrine cells; 99% of cells are exocrine
    • therefore, main function is digestion
    • Exocrine cells are arranged in clusters called acini
    • Endocrine cells are among acini are clusters islets of Langerhans
    • Located posterior & inferior to stomach-spleen is located by tail of pancreas
  139. acini
    • provide the exocrine function of pancreas
    • clusters of cells making up outside layer - form majority of pancreas
    • produce digestive enzymes that are secreted into the small intestine
  140. islets of Langerhans
    • contain 4 different types of endocrine cells
    • also called pancreatic islets
    • tiny clusters of cells found in middle of pancreas
    • cells: alpha, beta, delta, and F cells
  141. Glucagon vs insulin
    are antagonist
  142. Alpha cells
    • type of endocrine cells making up 17% of pancreatic islets
    • secrete glucagon - raise blood sugar:
    • Increases blood glucose levels
    • Acts on hepatocytes to convert glycogen to glucose - released into blood raises glucose levels to normal
    • *stimulated by low blood glucose levels
    • **if blood glucose continues to rise, hyperglycemia inhibits release of glucagon
  143. hepatocytes
    liver cells
  144. Beta cells
    • type of endocrine cell making up 70% of pancreatic islets
    • secrete insulin - lowers blood sugar
    • Speeds conversion of glucose to glycogen & get it out of blood stream
    • accelerates facilitated diffusion of glucose into cells by making transporters to cross membrane
  145. What all does insulin do?
    • Accelerated facilitated diffusion of glucose into cells (increases # of transport proteins)
    • Speed conversion of glucose into glycogen
    • Increases uptake of amino acids by cells to increase protein synthesis
    • Speeds up synthesis of fatty acids
    • Decreases gluconeogenesis
  146. Delta Cells
    • type of endocrine cell making up 7% of pancreatic islets
    • secrete somatostatin:
    • Acts to inhibit release of insulin and glucagon
    • *Your gonna Die
  147. F cells
    • type of endocrine cell making up 6% of pancreatic islets
    • secrete pancreatic polypeptide
    • inhibits somatostatin (digestion)
    • * Fatty needs a diet
  148. hypoinsulinism
    can be lack of production or lack or response to insulin, or both
  149. diabetes mellitus
    • most common disorder affecting insulin production
    • results in person not producing enough insulin, or they don't respond well to minimal or moderate amount they do produce
  150. Type I diaetes
    • also called juvenile-onset & insulin dependent
    • typically occurs in younger population
    • results in complete loss of beta cells
    • Genetically influenced but environmentally induced
    • Autoimmune antibody against beta cells resulting in their destruction
    • With loss of beta cells, pt doesn't have insulin to help facilitate diffusion of glucose
  151. Type II
    • Also adult-onset & non-insulin dependent
    • more genetically influence than type I
    • Pt still produce insulin, but either don't produce enough or don't effectively utilize what they do produce; OR BOTH
    • One of leading causes is obesity
  152. decreased insulin sensitivity
    • happens when individuals overeat = continually giving pancreas a carb challenge
    • Pancreas must secrete insulin to assist w transport of glucose out of blood and into cells; if this happens too much, body may respond by "down-regulating" insulin receptors
    • So even though insulin is present, body isn't responding in normal faction & more glucose stays in blood stream
  153. metabolic syndrome
    • a cluster of hyperlipidemia, obesity, hypertension, and insulin resistance
    • Most medical scientist would reclassify type II diabetes as part of this
  154. hyperinsulinism
    • most common in diabetic pts that take too much insulin compared to their caloric intake
    • Low glucose causes increased amount of epinephrine, glucagon, and hGH (causing anxiety, sweating, tremors, increased HR, hunger, and weakness)
    • Brain cells deprived of glucose, so mental disorientation, convulsions, and unconsciousness can occur
    • can result in "insulin shock"
  155. diabetic coma
    • the pts glucose is critically high
    • commonly occurs in hypoinsulinism
    • pt doesn't have or take enough insulin or meds to match their food intake
  156. ketoacidosis
    • occurs with a complete lack of insulin involving type I diabetics
    • Pt doesn't have any available glucose due to complete lack of insulin
    • Therefore, they utilize fatty acids for their energy source
    • The byproducts from fatty acid metabolism are ketoacids (simply called ketones)
    • The overproduction of ketones (cause they have NO insulin) causes a persons pH to drop and become acidic
    • *person with type II produces enough insulin to not completely rely on fatty acid metabolism for ATP
  157. gonads
    • ovaries in women, testes in men
    • organs responsible for gamete production
    • also have endocrine function
    • in response to FSH and LH from pituitary, gonads produce various hormones:
    • ovaries produce estrogen and progesterone
    • testes produce testosterone
  158. Gonadal hormone functions
    • the development and maintenance of the secondary sex characteristics and fertility
    • *secondary sex characteristics are those that are present during and after puberty
  159. Estrogens and progesterone
    • regulate the female reproductive cycle
    • Maintain pregnancy
    • breast development and maturation
    • widening of the hips
    • adipose tissue deposition in the breasts and around the hips
  160. Testosterone
    • sperm production (spermatogenesis)
    • hair growth patterns
    • increased skeletal and muscular growth
    • voice changes
  161. Pineal gland
    • attached to top of the third ventricle; is part of the epithalamus
    • produces and secretes the hormone melatonin
    • *I'm going to "Pin" you down in bed so you will sleep
  162. melatonin
    • hormone which is believed to assist with the setting of the daily biological clock by:
    • promoting sleepiness
    • Controls seasonal and daily cycles
    • More is released during darkness than light
  163. Thymus gland
    • located in the mediastinum (behind sternum and btwn lungs)
    • important for immune system
    • secretes thymosin
  164. Thymosin
    along with other related hormones, secreted from the thymus gland and encourages the maturation of T-lymphocytes (T cells)
  165. T Cells
    a type of white blood cells (lymphocyte) that destroys microorganisms and foreign substances through direct cellular contact or by recruiting other white cells
  166. stressor
    • anything that disrupts normal homeostasis
    • Ex: chemicals, psychological stress, heat, cold, confinement, injury, hemorrhage, etc.
    • *can be helpful in some situations; it heightens responsiveness and helps increase concentration = eustress
    • *stress that has negative effect is called distress, is always harmful
  167. GAS
    • general adaption syndrome
    • also called the "stress response"
    • the body's response to emergency or stressful situations, real or imagined
    • *the idea that a variety of stressors would invoke a very similar response, regardless of stressor type. The common effects, controlled mainly by hypothalamus, were termed the "stress response"
    • **The goal is to maintain homeostasis
  168. Three stages of GAS
    • fight - or - flight
    • resistance reaction
    • exhaustion
  169. Fight or flight stage of stress response
    • initiated by hypothalamus - stimulated the adrenal medulla by sympathetic nervous system
    • body is trying to quickly activate mechanisms to allow immediate physical response:
    • provided large amts of glucose and oxygen
    • mental alertness
    • increased blood flow to essential organs
  170. resistance action
    • initiated by hypothalamus by secreting the releasing hormones: ACTH, hGH and TSH
    • Since this is a hormonal response instead of neural, can allow body to fight stressor longer after fight/flight diminishes
    • The hormones:
    • increase BP, glycogen and protein catabolism, lipolysis, and sodium/water retention
    • decreases inflammation, wound healing and immune response
  171. exhaustion stage of stress response
    • the body's resources have depleted and resistance reaction can't be maintained
    • Prolonged exposure to resistance response causes immune suppression, muscle wasting, ulceration of GI tract, failure of pancreatic cells and depletion of K+
    • Common relationship with chronic diseases
    • Death is a potential severe consequence

Card Set Information

Author:
 jskunz
ID:
 261650
Filename:
 HTHS Mod 14
Updated:
2014-02-21 20:37:28
Tags:
HTHS Mod 14
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Description:
Endocrine System
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