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Metabolic Endocrinology > Midterm 1 Review > Flashcards

Midterm 1 Review Flashcards

1
Q

How do endocrine cells function?

A

Secretes hormones into blood vessels, target cells may be distant

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2
Q

How do paracrine cells function?

A

Secretes hormones which act locally on neighbouring cells

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3
Q

How do autocrine cells function?

A

Secretes hormones which act on themselves or on identical neighbouring cells

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4
Q

How do neuroendocrine cells function?

A

Secretes molecules from axon terminals into the bloodstream

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5
Q

How do neurotransmitter cells function?

A

Secretes molecules from axon terminals to actiate adjacent neurons

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6
Q

What do all cholesterol derivatives contain?

A

A sterol ring

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7
Q

Where are peptide hormones stored?

A

Secretory vesicles in the cytoplasm

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8
Q

How are hormones transported in the blood?

A
  • Hydrophilic molecules can circulate in a free state
  • Hydrophobic hormones will require a carrier protein specific to the hormone
  • Binding proteins acts as a buffer: transports hormone and protect it from degradation
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9
Q

What are some common techniques used in endocrinology?

A
  • Ablation
  • bioassays
  • immunoassays
  • blot test
  • in situ hydridization
  • autoradiography
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10
Q

Compare bioassays and enzymoimmunoassays

A
  • Bioassays measures the response of an animal or cell to a hormone (E.g rabbit test, human urine is injected into rabbit to detect levels of hCG, if present rabbit ovaries would ovulate)
  • Bioassays are time consuming and does not accurately measure hormone levels
  • Enzymoimmunoassay competitively binds an antibody to its antigen
  • EIAs do not require radioactive tags, it is tagged with a compound that changes colours
  • EIAs can be usde on blood and urine samples depending on the hormone
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11
Q

When does phosphorylation of tyrosine occur? What are they used for?

A

Typically at the beginning of a signal cascade, they serve as a docking site for down stream signal proteins

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12
Q

What type of cell surface receptor does insulin use?

A

Intrinsic tyrosine kinase activity

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13
Q

What are the sequences of events after insulin binding?

A
  • autophosphorylation of intracellular domain of receptors
  • docking and phosphorylation of IRS-1 and IRS-2
  • activation of two major signal pathways
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14
Q

What is the P13 kinase pathway required for?

A
  • Maintainence of active dephosphorylated glycogen synthase: increase glycogen synthesis
  • Movement of glucose transporter GLUT4 to the outer cell membrane: increase glucose uptake
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15
Q

What are the steps of the P13 kinase pathway?

A
  • IRS-1 is phosphorylated by the insulin receptor: P13K converts PIP2 to PIP3
  • PKB bound to PIP3 is phosphorylated by PDK1
  • GSK3 inactivated by phosphorylation cannot convert glycogen synthase to its active form: glycogen synthase remains active
  • PKB stimulates movement of glucose transporter GLUT4 from internal membrane vesicles to the plasma membrane: increase glucose uptake
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16
Q

What does the MAPK pathyway do?

A
  • Changes gene expression
  • Increase cell dividision
  • Activated by GH
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17
Q

How many times does the transmembrane domain cross through the membrane?

A

7 times

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18
Q

What are the functions of the G alpha subunits?

A
  • Gs alpha: activates adenylate cyclase
  • Gi alpha: inhibits adenylate cyclase
  • Gq alpha: activates phospholipase C
  • G0 alpha: activates ion channels
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19
Q

What are the three domains of the intracellular receptor?

A
  • DNA hormone specific binding domain
  • Conserved DNA binding domain
  • Hypervariable domain
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20
Q

What are the target cells of the anterior pituitary?

A
  • Somatotrophs (GH): 40 - 50%, all tissues
  • Corticotrophs (ACTH): 15 - 20%, adrenal glands, adipocytes, melanocytes
  • Mammotrophs (PRL): 10 - 15%, breasts and gonads
  • Gonadotrophs (LH, FSH): 10 - 15%, gonads
  • Thyrotrophs (TSH): 3 - 5%, thyroid glands
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21
Q

Which anterior pituitary subgroups are basophiles?

A
  • thyrotrophs
  • corticotrophs
  • gonadotrophs
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22
Q

Which anterior pituitary subgroups are acidophiles?

A
  • somatotrophs

- lactotrophs

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23
Q

What are the features of the pineal organ?

A
  • pine cone shaped
  • size of a rice grain
  • interprets visual signals
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24
Q

What does the pineal gland secrete?

A

Melatonin

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25
Q

What is melatonin used for?

A
  • Adjustment of jet lag

- Sleeping aid in the elderly

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26
Q

What are the main functions of oxytocin?

A
  • Contraction of smooth muscles

- Lactation: through stimulation of muscles

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27
Q

Where are osmoreceptors located? What is its main function?

A

Hypothalamus

Detects changes in blood plasma and tries to maintain a set point

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28
Q

What happens during pregnancy in regards to the osmostat?

A
  • osmostat will reset
  • total body water increases 7 - 8L due to vasodilation
  • placenta prouces enzyme to degrade vsaopressin
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29
Q

What are IGF-I and IGF-II dependent on? What are they important for?

A
  • GH dependent

- important for growth and development

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30
Q

What is an older name for IGFs?

A

Somatomedins

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31
Q

What does GH and IGF promote?

A

Promotes the growth of long bones at the epiphyseal plates by depositing calcium matrix which increase bone growth

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32
Q

How do GH receptors work?

A

Acts through the recruitment of tyrosine kinase and activation of STATs, MAPK or IP3K

33
Q

Why do people use exogenous GH treatment?

A

Elderly use exogenous GH to decrease body fat, increase lean muscle tissue and bone tissue, improve some cognitive functions

34
Q

What is the main function of prolactin?

A

Post partem activation of lactation

Development of mammary gland

35
Q

What inhibits prolactin?

A

Dopamine

36
Q

Where does prolactin stimulate milk secretion?

A

Alveolar epithelial cells

37
Q

What is the tanning process?

A
  • caused by UV lights
  • uv lights cause DNA damage
  • p53 levels are too high
  • melanin will be deposited into the skin
  • acts through paracrine function
38
Q

What does ACTH stimulate?

A

Stimulates the adrenal cortex to release cortisol

39
Q

Who usually has a GH deficiency?

A

Elders, usually take alternative GH to improve quality of life
they will have a decrease in muscle strength, lowered exercise tolerance, diminished libido

40
Q

What are the side effects of gonadotrophin deficiency?

A

Oligoamenorrhea, dimished libido, infertility, hot flashes

41
Q

What are the side effects of ACTH deficiency?

A

Malaise, fatigue, anorexia, hypoglycemia

42
Q

What are the side effects of TSH deficiency?

A

Malaise, leg cramp, fatigue, dry skin, cold intolerance

43
Q

What is doping?

A

The use and abuse of performance enhancing substances in elite sports

44
Q

What are some of the motivations for the use of doping?

A
  • Enhanced performance: increased strength, endurance, alertness, aggression
  • Drive
  • Relaxation
  • Weight control
  • Hide other drug uses
  • Social support
45
Q

What is the difference between elite and adolescent doping use?

A

Elite athletes use doping ecause it is the edge they feel they need to win
Adolescent athletes use doping typically due to peer/coach pressure

46
Q

What are some excuses used for reason of doping?

A
  • Spiking
  • Testing procedures
  • Natural occurence
  • Pre-existing medical condition
47
Q

What are beta-blockers use in doping?

A
  • reduce blood pressure
  • anti-anxiety
  • used in sports that require a steady hand
48
Q

What is erythropoeitin?

A
  • released by the kidneys in response to low hematocrit
  • stimulates RBC production from bone marrow
  • manufactured by recominant DNA techniques
49
Q

Why do people use blood doping?

A
  • induced erythrocythemia: increase in Hb following reinfusion
  • increase oxygen carrying capacity of Hb
  • if there is more oxygen carrying capacity , more ATP production, more energy for muscles
50
Q

What are the steps for blood doping?

A
  • autologous reinfusion method: 2 units of blood is removed 4 - 8 weeks prior to competition
  • Hb/Hct returns to pre-transfusion levels
  • reinfusion 1 - 7 days prior to event
  • typically used in treatment for anemia
51
Q

How is blood doping detected?

A
  • measure Hct> 50
  • measure serum Fe and bilirubin
  • urine test is not reliable
52
Q

What are the negative side effects of doping?

A
  • baldness
  • reduced sperm count
  • enlarged prostate
  • shrinkage of testicles
  • mood swings
  • strokes and blood clots
    (for women):
  • reduced breast size
  • enlarged clitoris
  • increase in facial and body hair
  • menstrual problems
53
Q

How can athletes beat the system?

A
  • catherization
  • drink copious amounts of water
  • take diuretics to dilute urine
  • female athletes insert condoms with clean urine into vagina
54
Q

What is cell to cell communication?

A

Cells can communicate with each other through:

  • signals which are generated in special cells (hormone producing)
  • cells are exposed to many signals at the same time
  • other cells can recognise these signals and respond to them
55
Q

What are some endocrine rhythms?

A
  • Circadian rhythm: 24 hour cycle

- Infradian rhythm: 28 days

56
Q

What is the basic structure of a cell surface receptor?

A
  • Ectodomain: acts as a hormone binding protein
  • Hydrophobic transmembrane domain: transport
  • Cytoplasmic domain: induces a signaling cascade
57
Q

What are the three major types of cell surface receptors?

A
  • G coupled protein receptors
  • Intrinsic tyrosine kinase
  • Recruited tyrosine kinase
58
Q

How many binding sites does GH have?

A

Two binding sites to bind to two receptors

59
Q

What are the three branches of the signaling pathway of GH

A

Activation of JAK-2 phosphorylates itself, the cytoplasmic domain of the receptor and other proteins

  • Branch 1: activation of the transcription regulatory proteins STATs
  • Branch 2: activation of the MAPK pathway
  • Branch 3: activation of the P13K pathway which is responsible for insulin like metabolic effects of GH
60
Q

How do G protein coupled receptors relay signals?

A
  • Bind and activate G proteins
  • activation of G proteins will generate a response of second messengers (cAMP, DAG, IP3)
  • activation of phospholipase C or adenylate cyclic will inhibit or stimulate second messengers
61
Q

What are the two receptor classes?

A

Class 1: cytosolic - binds hormone then binds to DNA

Class 2: nuclear - already bound to DNA, then it binds to steroids

62
Q

What is the DNA binding domain?

A
  • two loops that form a zinc finger
  • Class 1 receptors which form complexes with heat shock proteins
  • zinc fingers are designed to recognise DNA spcifically in promoter regions
63
Q

How is the pituitary controlled?

A

By the nervous system through hypothalamus

64
Q

What is the supraoptic nuclei and paraventricular nuclei referring to?

A

Posterior pituitary

65
Q

What is the hypothalamic-hypophysiotropic nuclei refering to?

A

Anterior pituitary

66
Q

What are some of the side effects of melatonin?

A
  • daytime sleepiness
  • hypothermia
  • desensitization of melatonin receptors
  • possible interaction with those taking coumadin/warfarin
67
Q

What is the primary regulator of osmolarity?

A

Thrist

68
Q

How is BP lowered by vasopressin?

A
  • posterior pituitary releases vasopressin leading to vasoconstriction -> increasing arterial pressure
  • renal fluid reabsorption will increase blood volume and also increase arterial pressure
69
Q

What receptor does vasopressin bind to?

A
  • G alpha S which will activate cAMP
  • PKA will cause aquaporin 2 to be inserted into the membrane to uptake H20
  • aquaporin is recycled and stored in the cytoplasm when it is not required
  • produces more concentrated urine and decrease urine output
70
Q

What is essential for the initation and maintainence of milk secretion?

A

Prolactin and cortisol

71
Q

What inhibits prolactin?

A

Dopamine

72
Q

Why do athletes inject themselves with GnRH?

A

To manipulate their body to produce higher levels of androgens
GnRH does not leave a trail in the body and have a shorter half life

73
Q

What is cycling in terms of steroid use?

A

Taking multiple doses over a specific period then stopping for an equal or longer amount of time to decrease tolerance

74
Q

What is stacking?

A

using a combination of anabolic steroids to avoid tolerance from developing

75
Q

What is plateauing?

A

drugs will become ineffective after a certain level , reaches a threshold

76
Q

What is tapering?

A

slowly decreasing steroid intake

77
Q

What is pyramiding?

A

gradual increase then decrease in doses during a single cycle

78
Q

What is tetrahydeogestinone?

A

A synthetic drug created by a nutritional supplemental company

  • undetectable
  • extremely potent anabolic steroid
79
Q

What are the steps of the MAPK pathway?

A
  • insulin receptor binds insulin and undergoes autophosphorylation
  • insulin receptor phosphorylates IRS-1 on its tyrosine residue
  • SH2 domain of Grb2 binds P-tyr of IRS-1: release of GDP
  • activated Ras binds and activates Raf-1
  • Raf-1 phosphorylates MEK on two ser residues: MEK phosphorylates MAPK on a Thr and Tyr residue

Metabolic Endocrinology (4 decks)

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