Module 9 - Endocrine

  1. Describe the blood supply to the thyroid
    2 arteries: Sup. Thyroid a (off ECA); inf. thyroid a (off thyrocervical trunk)

    3 veins: sup and middle vv (IJV); inf thyroid (into left brachiocephalic trunk)
  2. Describe the arterial supply of the suprarenal gland
    • sup. suprarenal a: off of phrenic a
    • middle suprarenal a: off of abdominal aorta
    • inferior suprarenal a: off renal a

    for both sides
  3. Describe the location of the pancreas
    • -Right: duodenum
    • -Left: spleen
    • -anterior: transverse mesocolon
    • -posterior: aorta, renal vessels, left kidney, diaphragm
    • -superior: splenic vessels
    • -inferior: 3rd part of duodenum
  4. List 4 nontypical endocrine organs.
    • stomach: gastrin
    • small intestine: secretin and CCK
    • heart: ANP
    • placenta: hCG
  5. Describe development of parathyroid glands
    • -from endoderm
    • -3rd pharyngeal pouch to inferior
    • -4th pharyngeal pouch to superior

    -think of it swinging down like a door
  6. What does the gubernaculum do?
    pulls the gonad into the pelvis.
  7. What is the difference between peptide, amine hormones, and steroid hormones
    • -peptide: bind to cell surface receptors, small proteins
    • -amine: made from tyrosine and tryptophan, cell surface receptors except T3 and T4
    • -steroid: derived from cholesterol, bind intracellular receptors that regulate gene transcription
  8. What activates or inhibits AC (adenylyl cyclase)
    • G alpha s activates
    • G alpha i inhibits
  9. What are the differences between steroid and paptide/amine hormones with regards to:
    -storage pools
    -cell membrane interaction
    -response time
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  10. What does the post pit. contain?
    • -pituicytes (glial cells)
    • -fenestrated capp's
    • -unmylinates axons (herring bodies at ends)
  11. list some acidophils and basophils in the ant. pituitary
    • acidophils:
    •   -somatotrophs: GH
    •   -lactotrophs: prolactin
    • basophils:
    •   -gonatotrophs: LH and FSH
    •   -thyrotrophs: TSH
    •   -corticotrophs: ACTH
  12. list 3 unique features of the thyroid glands
    • -hormones need iodine
    • -can store hormones up to three months (in colloid)
    • -although T3 and T4 are peptides, their receptors are intracellular
  13. Describe the synthesis of thyroid hormone
    • 1) thyroglobulin is made in the follicular cell
    • 2) Iodide is captured from the blood
    • 3) Iodide is oxidized to I2 in the follicular lumen by thyroid peroxidase
    • 4) Iodination of thyroglobulin to make MIT and DIT
    • 5) coupling reaction MIT and DIT molecules are combined to make T3, two DIT make T4. All 4 molecules stay attached to thyroglobulin and hang out in the colloid until thyroid is stimulated.
    • 6) thyroglobulin endocytosed when thyroid stimulated
    • 7) lysosomal proteases break T3 and T4 (10x more T4) from thyroglobulin. T3 and T4 released to blood.
    • 8) MIT and DIT are recycled as thyroglobulin and iodide is salvaged.
  14. Describe what the thyroid hormone does with regards to: BMR, carb, lipid, protein metabolism, thermogenesis, ANS
    • -BMR increases
    • -carb: inc. gluconeogenesis, inc. glycogenolysis, no effect on serum glucose
    • -protein: increases synthesis and breakdown, increased muscle wasting
    • -lipid: increased lipogenesis, increased lipolysis decreased serum cholesterol
    • -increased thermogenesis
    • -ANS: increased beta adrenoreceptors (increased sens to chatecholamines, which remain at normal levels)
  15. list the effects of thyroid hormone on: bone, liver, brain, heart, adipose, muscle, gut
    • -bone: increase both osteoblast and osteoclast activity
    • -liver: triglyceride and cholesterol metabolism
    • -brain: axon growth
    • -heart: increased iontropy and chronotropy, reduced peripheral resistance
    • -adipose: breakdown of lipids
    • -muscle: increased protein breakdown
    • -gut: absorb more carbohydrates
  16. describe the conversion of T3 to T4
    T4 is converted to the more active T3 in the liver and kidneys via 5-ionidase
  17. List three disorders associated with hypothyroidism, one with hyper
    • -Hypo
    •   -Cretinism: retardation due to low iodine
    •   -Myxedema: dermal edema due to increased protein deposition
    •   -Iodine-deficient goiter
    • -Hyper
    •   -Graves: B lymphocytes errantly produce TSI, which mimics the effects of TSH on the thyroid. produces a goiter and other problems
  18. Describe the inhibition of PTH release from receptor to vesicle
    • 1)external Ca++ receptor stimulates G-alpha-q
    • 2) splits PIP2 to IP3 and DAG
    • 3a) IP3 releases Ca++ from ER
    • 3b) DAG activates PKC
    • 4) both the Ca++ (internal) and PKC stop the vesicles from being released and the PTH being released.

    In MOST cells the Ca++ and PKC cause the hormone to be released, this is a special case!
  19. List the 2 key functions of PTH
    • 1) promotes Ca++ reabsorption in the ascending LOH and DCT of nephron
    • 2) reduces reabsorption of phosphates in PCT and DCT
    • 3) creates active vit D, further promoting renal Ca++ reabsorption 
    • 4) bone reabsorption further increasing serum Ca++
  20. Describe the three types of communication between pancreatic islet cells.
    • 1) humoral: via blood flowing from the centre to the periphery of the islet
    • 2) cell-cell: gap junctions
    • 3) neural communications: innervated by symp and para.
  21. Describe the functions of insulin
    • 1) increase glucose transport into cells
    • 2) increase glycogenesis
    • 3) increase lipogenesis and protein synthesis
  22. Describe type II and type I diabetes and the relationship between the two
    -Type II diabetes is due to a problem with the insulin receptor or the subsequent cascade.

    -Type I diabetes is a problem with the beta islet cells, can be immunological. 

    -Lots of times with type II diabetes, the beta islet cells burn out after trying hard to lower the glucose levels (which aren't being lowered because of the broken receptors)
  23. List three sources of somatostatin
    • 1) delta cells
    • 2) D-cells of GIT
    • 3) hypothalamus (paraventricular nucleus)
  24. Describe the release of insulin by beta cells, from receptor to secretion
    • 1) Glucose enters cell via the glut2 channel 
    • 2) When there is high glucose, there will be higher ATP, which causes the Katp channels to close
    • 3) this causes K+ to build up in the cell (along with the slow trickle of Na+ that was already coming in) causing depolarization
    • 4) depol. triggers some voltage-gated Ca+ and Na+ channels to open
    • 5) this causes further depolarization, opening the voltage-dependent calcium channels (VDCC) to open and let in a TON of Ca++
    • 6) This Ca++ causes insulin exocytosis
    • 7) K+ channel will cause reploarization
  25. What type of receptor is the insulin receptor?
    receptor tyrosine kinase (RTK) because it phosphorylates tyrosine residues on itself and other proteins.
  26. What are the three things that determine insulin receptor numbers
    • 1) receptor synthesis
    • 2) endocytosis of receptors
    • 3) endocytosis by degradation
  27. The ability of insulin to act on a cell depends on what three factors
    • 1) number of receptors
    • 2) receptor affinity for insulin
    • 3) receptor's ability to transduce signal.
  28. What are three mechanisms that insulin receptor can transmit its signal
    • 1) SH-2 proteins: bind and phosphorylate tyrosine groups on the insulin receptors (imp. for lipid metabolism)
    • 2) TK can phosphor. and activate many cytoplasmic proteins
    • 3) phosphor. insulin-receptor substrates (IRS), this one is most important
  29. List the three areas where insulin exerts its effects
    Liver, adipose tissue, muscles
  30. Describe the effects insulin has on the liver
    • -stores glucose as glycogen
    • - inhibits gluconeogenesis (via PEPCK) 
    • -lipogenesis 
    • -stimulate protein metabolism
  31. describe the effects insulin has on muscle
    • -uptake of glucose via glut4
    • -convert glucose to glycogen
    • -increase glucose breakdown
    • -protein synthesis in skeletal muscle
  32. Describe the effects insulin has on adipose tissue
    • -increased uptake of glucose via GLUT4
    • -increase breakdown of glucose
    • -increase triglyceride formation
    • -enhances production of lipoprotein lipase
  33. List the microvascular complications of diabetes
    • 1) diabetic retinopathy
    • 2) diabetic nephropathy (affects SM in afferent arteriole)
    • 3) diabetic neuropathy (PNS)
  34. List the macrovascular complications of diabetes
    • central mechanism is atherosclerosis, leading to narrower walls
    • 1) coronary artery disease/heart disease
    • 2) stroke
    • 3) peripheral artery disease
  35. List the 8 functions of cortisol
    • 1) increase blood glucose concentration
    • 2) anti-inflammatory activity (inhibits phospholipase A2, recall from earlier)
    • 3) optimize vascular responsiveness to catecholamines
    • 4) enhance glom. filtration rate
    • 5) decrease osteoblast activity
    • 6) decrease Ca+ absorption from GIT
    • 7) alters CNS (mood and cognition)
    • 8) may cause insulin resistance
  36. What stimulates the release of aldosterone
    • 1) renin-ANG II
    • 2) ACTH
    • 3) potassium levels
  37. List the location, affinity, typical response, and example of response for alpha1 receptors
    • Location: most symp. target cells
    • affinity: NE>E
    • typ. response: excitory
    • example: increased SM contration
  38. List the location, affinity, typical response, and example of response for alpha2 receptors
    • Location: digestive system
    • affinity: NE>E
    • typ. response: inhibitory
    • example of response: decreased motility
  39. List the location, affinity, typical response, and example of response for beta1 receptors
    • location: heart
    • affinity: NE=E
    • typical response: excitory
    • example of response: increased ionotropy and chronotropy
  40. List the location, affinity, typical response, and example of response for beta2 receptors
    • Location: skeletal muscle, some smooth muscle in organs and selected BVs
    • affinity: E only
    • Typical response: inhibitory
    • examples of response: bronch. dilation, arteriolar dilation in skeletal m arterioles and cardiac m
Card Set
Module 9 - Endocrine