MCAT BIOLOGY Endocrine and respiratory system

  1. endocrine system
    organs known as glands that secrete hormones
  2. 3 types of hormones
    • peptide
    • steroids
    • amino acid derivatives
  3. peptide hormones range in size and derived from larger polypeps during post translational modifications where they are then transported through the Golgi for more modifications to make an active hormone and sent to right location and then release via exocytosis
    the effects are rapid but short lived unless constant stimulation has occurred, but are water soluble and do not need carriers
  4. peptide hormones are charged so...
    cannot pass PM so they bind to extracellular receptor
  5. first messenger and second messenger
    1st is the peptide before it links to receptor while the 2nd is when the pep is linked and causes another signal
  6. during a signaling cascade, amplification of the second messenger
    causes an intensity of the signal
  7. common second messengers are
    • cAMP
    • inositol triphosphate (IP3)
    • Ca
  8. the peptide hormone triggers the receptor to activate or inhibit an enzyme fro working
  9. steroids are derive from cholesterol and can cross PM due to being from non polar molecules so their receptors are intercellular or intranuclear. Can bind to DNA to increase gene production
    slower but longer lived because alters amount of mRNA and protein in the cell. not water soluble, need to be carried by proteins to travel but are inactive until they are released
  10. amino acid derivatives less ommon but are epine,norepine,triiodothyronine, and thyroxine. derived from 2 AA and need few modifications
  11. direct hormones
    act directly on target tissue (insulin causes uptake of glucose by muscles)
  12. tropic hormones
    need an intermediary to act, so multiple things must act after this hormone before anything causes a reaction
  13. 8 organs of endocrine system
    • pineal gland
    • hypothalamus
    • pituitary gland
    • parathyroid glands
    • thyroid
    • adrenal
    • pancreas
    • ovaries
  14. by hypothalamus regulating pit gland through tropic hormones, it is capable of having organism wide effects
  15. hypo secretes compounds into hypophyseal portal system which is a blood vessel system that connects hypo with anterior pituitary, hormones travel down portal stalk and bind to receptors in anterior which release other hormones
  16. tropic hormones released by hypo and their effects
    • FSH & LH
    • GH
    • TSH
    • ACTH
  17. how corticotropin releasing factor works to produce adrenocorticotropic hormone
    • crf from hypo will stim AP to secrete ACTH to increase cortisol in blood by adrenal cortex, but too much will cause H and AP from releasing CRF and ACTH
    • (negative feedback loop)
  18. oxytocin function
    horm stim uterine contractions during labor and lactation
  19. ADH function
    increase re absorption  of h2o in collecting ducts of kidneys
  20. 7 products of AP
    4 tropic
    3 direct
    • prolactin,endorphins,growth hormone
  21. prolactin function
    • stim milk production in mammary glands
    • high levels of estro and proges allow for the preparation for lactation
    • estro,proges,prolac levels drop causes lactation to begin
  22. nipple stimulation  causes activation of hypo which causes 2 reactions
    • oxytocin released from posterior pit = contraction of smooth muscle of breast and ejection of milk
    • hypo stops dopamine release onto AP, allows prolac release, cause production of milk and regulation of supply
  23. growth hormone function
    • needs lots of glucose, prevents glucose uptake in certain tissues and stim breakdown of fatty acids and is stim by GnRH
    • too much causes giantism, too little is dwarfism
  24. bone growth originates where and what occurs
    special regions known as epiphyeal plates that seal during puberty but can have some effect on smaller bones such as hands and feet (acromegaly)
  25. positive feedback continue to move things forward and activate while having an end point
  26. thyroid function 2
    • controlled by thyroid stim hormone
    • sets basal metab rate
    • calcium homeostasis
  27. triiodothyronine (T3) thyroxine (T4) are produced by the iodination of the amino acid tyrosine in the follicular cells of the thyroid
  28. increase in T3 and T4 increase cell resp, which increase protein and FA turnover which speeds up production and breakdown
    increased levels of plasma in thyroid have a negative feedback which leads to decreased TSH and TRH synthesis which also prevents excessive secretion of T3 and T4
  29. two hormones released by posterior pit are synthesized in hypo
  30. hypothyroidism cause and symptoms
    • thyroid hormones are secreted in insufficient amounts or not at all
    • lethargic, slowed respiratory and heart rate, weight gain
    • hyperthyroid is the complete opposite
  31. cretinism
    mental retardation or developmental delay due to error in thyroid hormones needed in children
  32. follicular cells produce thyroid hormones and C-cells that produce calcitonin
  33. 3 ways calcitonin decreases plasma calcium levels
    • increase calcium excretion from kidneys
    • decrease ca absorption from gut
    • increased storage of ca in bone
  34. parathyroid hormone (PTH) 3 characters
    • hormone produced by the parathyroid glands
    • serves as an antagonistic hormone to calcitonin by freeing up calcium
    • activates vitamin D
  35. vitamin d function
    required for absorption of Ca and phosphate in gut
  36. 3 funtion classes of steroid hormones from coricosteroids from adrenal cortex
    • glucocorticoids (sugar)
    • mineralocorticoids (salt)
    • cortical sex hormones (sex)
  37. glucocorticoids
    steroid hormones that reduce glucose levels
    • both raise blood glucose by increasing glucogenesis and decreasing pro syn
    • decrease inflammation and immunological responses
    stress hormone b/c released during a time of physical and emotional stress, increase blood sugar, acts as a source of fuel to react to dangerous stim
  40. mineralocorticoids
    • salt and water homeostasis, effect on kidneys
    • (aldosterone)
  41. aldosterone function (under control of renin-angiotensin-aldosterone)
    • increase sodium reabs in distal convoluted tubule and collecting duct of nephron, which increase water into blood stream increasing blood volume and pressure
    • decreases reabs of K and H ions in same nephron segments which promote excretion in urine
  42. how to produce aldpsterone from RAA
    • decreased BP causes juxtaglomerular cells of kidney to secrete renin
    • cleaves inacive angiotensin to active form angiotensin I which is converte to angiotensis II by angiotensis converting enzyme (ACE) in lungs
    • AII stim adrenal cortex to secrete aldosterone
    • (BP causes this to create a negative feedback and decrease renin)
  43. stress responses involve both cortisol and epinephrine, how so
    • cortisol is important for long term slow stress responses, catecholamines are important for short term fast stress response.
    • cortisol increases syn of catecholamines which leads to their release
  44. islets of langerhans
    a grouped of hormone producing cells throughout the pancreas
  45. 3 types of islets in pancreas
    • alpha - secrete glucagon
    • beta - secrete insulin
    • delta - secrete somatostatin
  46. glucagon (secreted by alpha islets)
    • secreted during times of fasting
    • stim degradation of pro and fat
    • conversion of glycogen to glucose
    • produce new gluco via glucogen
  47. insulin (secreted by beta islets)
    • when blood glucose is high
    • induces muscle and liver cells to take up glucose and store as glycogen
    • stim anabolic process (fat and pro syn)
  48. diabetes mellitus
    underproduction, insufficient secretion, or insensitivity to insulin
  49. 2 things diabetics often report having because of diabetes
    • polyuria (increase urination)
    • polydipsia (increased thirst)
  50. type 1 diabetes (insulin dependent)
    autoimmune destruction of the B-cells of pancreas, produce little to no insulin due to B-cells destruction
  51. type 2 diabetes (noninsulin dependent)
    • receptor level resistance to effects of insulin
    • partially inherited but also due to environmental factors
  52. somatostatin
    an inhibitor of insulin and glucagon secretion, high glucose and AA concentrations stim its secretion
  53. pineal gland is a small gland in the brain that is said to be involved in cardiac rhythms
  54. erythropoientin
    stim bone marrow to increase production of erythrocytes, secreted due to low oxygen levels
  55. atrial natriuretic peptide (ANP)
    • reg salt and water balance
    • cells in atria are stretched from excess blood volume, they release ANP
    • promotes excretion of sodium which increases urine volume which lowers BP
  56. thymosin (from thymus)
    for proper t-cell development and differentiation
  57. traveling of air through the respiratory system
    • air enters through external nares of the nose and pass through the nasal cavity where its filtered through mucous mem and nasal hairs (vibrissae)
    • goes through pharynx and larynx to the trachea through the bronchi to branched out bronchioles
    • bronchioles continue to divide until it reaches the aveoli where gas exchange occurs
  58. pharynx is behind the nasal cavity to the back of the mouth
  59. larynx is in front of pharynx and is has the epiglottis that covers the glottis when swallowing
  60. vocal cords are located in the larynx
  61. surfactant
    detergent that lowers surface tension and prevents the alveolus from collapsing
  62. pleurae
    • membranes that surround each lung
    • forms a sac against each long
    • visceral is the surface against the lung, the outer is parietal pleura
    • space between the sac is intrapleura space and has a thin layer o fluid that helps lubricate the pleural surfaces
  63. increase in lung expansion decreases the pleura
  64. external intercostal muscles
    one layer of muscles between the ribs that help expand the thoracic cavity
  65. intrathoracic volume
    volume of the chest cavity
  66. inhalation process
    • external intercostal muscles expand the thoracic cavity
    • diaphragm flattens and chest walls expand
    • the intrathoracic volume increases causing intrapleural pressure to decrease
  67. negative pressure breathing
    air sucked in from higher pressure environment (outside) an the driving force is the lower pressure in the intrapleural space compared with the lungs
  68. increase lung expansion = decrease in pleural
  69. diaphragm is under somatic control
  70. Image Upload 1
  71. exhalation process
    • air is pushed out and the process is sped up by internal intercostal muscles which oppose the action of the external intercostals
    • the rib cage pulls down and decreased the volume of the thoracic activity
    • lungs recoil and volume becomes smaller and pressure increases
  72. spriometer
    instrument used to measure the lung capacities and their volume
  73. residual volume
    the air that remains in the lungs after being exhaled
  74. 6 commonly tested lung volumes
    • total lung capacity (TLC)
    • residual volume
    • vital capacity
    • tidal volume
    • expiratory reserve volume
    • inspiratory reserve volume
  75. total lung capacity
    the max volume of air in the lungs when one inhales completely
  76. residual volume
    the min volume of air when one exhales completely
  77. vital capacity
    difference between the min and max volume of air in the lungs
  78. tidal volume
    volume of air inhaled or exhaled in a normal breath
  79. expiratory reserve volume
    the volume of additional air that can be forcibly exhaled after normal exhale
  80. inspiratory reserve volume
    volume of additional air that can be forcibly inhaled after normal inhalation
  81. ventilation
    is regulated by a collection of neurons in medulla oblong (ventilation center)
  82. how ventilation works
    • the medulla oblong (VC) fires rhythmically to contract respiratory muscles
    • neurons of the MO w/chemoreceptors are sensitive to CO2 so once the level rises the respiratory rate will increase and CO2 will be exhaled
  83. hypercarbia/hypercapnia
    partial pressure of the CO2 in the blood rising
  84. hypoxia
    low O2 conc in the blood
  85. Image Upload 2
    • capillaries bring deox blood from pulmon artery (right ventricle of heart)
    • diffusion of CO2 from blood into lungs and O2 into the blood
    • the oxygen blood returns to the left atrium of he heart via pulmon veins
  86. driving force for gas exchange
    pressure differential of the gases
    • when it arrives in the aveoli, blood has a low pp of O2 and a high pp of CO2
    • transfer of each down its concentration gradient occurs
  87. O2 in aveoli flows down conc gradient from aveoli to pulmon capillaries where it binds to hemo for transport
    CO2 flows down from cap to aveoli to get expelled
  88. vasodiliation/vascoonstriction
    • the transfer of thermal E that is regulated by body surfaces
    • **expand capillaries=more blood to pass,large amount of thermal E to be dissipated
  89. humans regulate using capillaries and sweat glands or muscle contraction
  90. the first line of defense occurs in the nasal cavity, how so??
    • small hairs (vibrissae) help to trap particle matter
    • lysozyme (found in tears and saliva) attack peptidogly walls of gram+
    • mucus traps particles while the cilia propel the mucus up the oral cavity to be expelled or swallowed
  91. mucociliary escalator
    the propelling of mucus up the oral cavity to be expelled or swallowed
  92. how the respiratory system plays a role in ph balance in the blood?
    • when the ph lowers, hydrogen ions increase (acidemia)
    • acid sensing chemoreceptors outside the blood-brain barrier send signals to the brain to increase respiratory rate
    • **due to increase in hydrogen ions, there will be a shift in bicarb buffer system to the left to make more CO2**
    • respiratory rate increases, more CO2 expelled
    • if blood is too basic (alkalemia), the bicarb buff will shift to the right to cause more H+ and bicarbo ions to be made
  93. CO2(g)+H2O(l)=H2CO3(aq)=H+(aq)+HCO3-(aq)
Card Set
MCAT BIOLOGY Endocrine and respiratory system
endocrine and respiratory system biology mcat flashcards