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Endo/Repro Exam 1 > 1. DSA > Flashcards

1. DSA Flashcards

1
Q

There are several mechanisms of transfer: autocrine, paracrine, endocrine and neuroendocrine.

A
  1. Autocrine- hormones bind to receptors on the cell that makes it. Ex. Growth factors
  2. Paracrine- hormones are released from cells and bind to receptor on nearby cells of a different type
  3. Endocrine- chemicals are secreted into the blood and carried by the blood and tissue fluids to the cells they act upon
  4. Neuroendocrine- neurons release hormones into the bloodstream, which acts upon another cell
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2
Q

What is the endocrine system?

A
  • regulates multiple organs in the body to help it grow and reproduce.
  • Homeostasis
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3
Q

What hormones does the hypothalamsus secrete?

A

THE DRUNK GIRL GOT SOME COURAGE

  • Thyroid- releasing hormone (TRH)
  • Dopamine
  • Growth hormone releasing hormone (GHRH)
  • Gonadotropin-releasing hormone. (GnRH)
  • Somatostatin
  • CRF (Corticotropin-releasing factor)
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4
Q

What hormones do they anterior pituitary secrete?

A

FLAT (tropic hormones- act on other endocrine glands to cause release of hormones) PEG (direct hormones)

  1. FSH
  2. LH
  3. ACTH
  4. TSH
  5. Prolactin
  6. Endorphins
  7. GH (growth hormone)

& MSH (which is a tropic hormone)

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5
Q

What hormones does the posterior pituitary. secrete?

A

ADH and Oxytocin

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6
Q

What hormones does the thyroid secrete?

A
  1. T3,
  2. T4
  3. Calcitonin
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7
Q

What horomes does the parathyroid secrete?

A

PTH

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8
Q

What hormones does the pancreas secrete?

A

Insulin and glucagon

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9
Q

What hormones does the adrenal medulla secrete?

A

EPI and NE

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10
Q

What hormones does the kidney secrete?

A
  1. Renin
  2. 1, 25- dihydroxycholecalciferol (calcitriol)
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11
Q

What hormones does the adrenal CTX secrete?

A
  1. Cortisol
  2. Aldosterone
  3. Adrenal androgens
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12
Q

What hormones do the testes and ovaries secrete?

A

Testes: testosterone

Ovaries: estradiol and progesterone

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13
Q

What hormones does the corpus luteum secrete?

A
  1. Estradiol
  2. Progesterone
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14
Q

What hormones does placenta secrete?

A

1. hCG

2. Estriol

3. Progesterone

4. hPL

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15
Q

There are three classes of hormones: [proteins and peptides], [amines] and [steroids]

Describe proteins and polypeptides and what are amines derived from.

A
  • Proteins and peptides are stored in vesicles until we need them.
  • Polypeptides with more than 100 aa are proteins; less than 100 are peptides.
  • Amines are derived from tyrosine.
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16
Q

There are three classes of hormones: [proteins and peptides], [amines] and [steroids].

Describe steroids.

A

Steroids are lipid-soluble and made from cholesterol.

We do not store them.

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17
Q

How are proteins hormones made?

A

Proteins are peptides are made from larger polypeptides.

  1. DNA is converted to mRNA in the nucleus.
  2. mRNA is translated into preprohormone on ribosomes.
  3. When the signal peptide is removed in the ER, the preprohormone–> prohormone.
  4. Prohormone- [golgi apparatus, where it is packed into secretory vesicles]. Once they are packed into vesicles, they are cleaved by proteolytic enzymes, forming the the final hormone.
  5. Stored in secretory vesicles until endocrine cell is stimulated
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18
Q

Stimulus for exocytosis of the secretory vesicle storing peptide/protein hormones are:

A
  1. Increase Ca2+ d/t depolarization
    • GCPR–> increase in cAMP–> + of PKA
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19
Q

Where are steroid hormones made and secreted? (3)?

A

1. Adrenal CTX

2. Gondads

3. Corpus luteum

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20
Q

How can we modify cholesterol –> steroid hormones?

A

1. Remove/add side chains

2. Hydroxylize/aromatize steroid nucleus.

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21
Q

Steroid hormones include (7):

A
  1. cortisol
  2. aldosterone
  3. estradiol
  4. estriol
  5. progesterone
  6. testosterone
  7. 1,25 dihydroxycholecalciferol (calcitriol)
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22
Q

Steroids are made from cholesterol. Where does the cholesterol come from?

A
  1. 80% is taken up as LDL particles through receptor-mediated endocytosis.
  2. De novo synthesis from acetyl coA
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23
Q

Steroids hormones will diffuse into the cell and act on cytoplasymic receptors or the nucleus. They have both genomic and non-genomic actions. What are they?

A
  1. Affect gene transcription by acting. on nuclear receptors
  2. Rapid steroid actions, such as specific-receptor mediated or direct steroid-membrane interactions
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24
Q

Amine hormones include ______________ and ___________, both of which are derived from _____________.

A
  1. Catecholamines
  2. Thyroid hormones

Both of which are derived from tyrosine.

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25
Q

Amine hormones include catecholamines and thyroid hormones, both of which are derived from tyrosine.

Where are they made and where do they bind to receptors?

A
  • Catecholamines are made in the cytosol and secretory granules and bind to receptors on the cell membrane
  • Thyroid hormones, on the other hand, are made in the thyroid gland and stored as thyroglobullin in follicles within the gland. They cross the cell membrane and bind to nuclear receptors.

Thus, amine hormones can bind to cell membrane receptors or nuclear receptors.

26
Q

What is the protein binding % and plasma half life of both thyroid hormones?

A
  1. Thyroxine (T4)
    • Protein binding: 99.97%
    • Half life: 6 days
  2. Thriiodothyronine (T3):
    • Protein binding: 99.7%
    • Half life: 1 day
27
Q

What is the pritein binding %. and half-life of steroid hormones: cortisol, testosterone and aldosterone?

A

Cortisol

  • Protein binding: 94%
  • Half life: 100 minutes

Testosterone:

  • Protein binding: 89%
  • Half life: 25 minutes

Aldosterone

  • Protein binding: 15%
  • Half life: 25 minutes
28
Q

What is the protein. binding %. and the plasma half-life of proteins; thyrotropin RH, insulin and ADH?

A
  1. thyrotropin (TRH)
    • Protein binding %: little
    • Half life: 50 minutes
  2. insulin
    • Protein binding %: little
    • Half life: 8 minutes
  3. ADH
    • Protein binding %: little
    • Half life: 8 minutes
29
Q

Fill in the blanks.

A
30
Q

Fill in the blank for anterior pituitary.

A
31
Q

Fill in the blank for posterior pituitary.

A
32
Q

Fill in the blank for thyroid.

A
33
Q

Fill in the blank for placenta.

A
34
Q

Fill in the blank for pancreas and kidney.

A
35
Q

Fill in the blank for the adrenal medulla.

A
36
Q

To maintain homeostasis, we need to be able to turn on and off hormone secretions. What are two ways we can do so?

A
  1. Neural stimulation will increase or decrease secretion.
  2. Feeback mechanisms: negative feedback is dominate.
37
Q

Hormone secretion can be turned on and off by. neural stimulation and feedback mechanisms, which occurs mainly through negative feedback. Why is positive feedback so rare?

A

It is mostly BAD: RARELY used to control homeostasis, self-augmenting.

38
Q

What are examples of positive feedback?

A
  1. During your menstrual cycle, increasing levels of estrogen cause FSH and LH release from AP, which further increases estrogen levels and leads to ovulation.
  2. When delivering a bb, oxytocin enhances labor contractions.
39
Q

_________ helps to maintain homeostasis of our organs.

A

Negative feedback.

40
Q

There is a long-loop negative feedback, short-loop negative feedback and ulta-short loop negative feedback. What is the difference between the three?

A
  • Long loop NF: hormones released from 3rd tier (endocrine gland) feedback to 1st tier (hypothalamus) and 2nd tier (pituitary gland)
  • Short loop: hormones from 2nd tier (pituitary) feedback to 1st tier (hypothalamus)
  • Ultrashort loop: endocrine gland inhibits its own secretion.
41
Q

Our endocrine system is organized into three endocrine axes. What are they?

A
  1. HPA axis (hypothalamus-pituitary-adrenal gland)
  2. HPT axis (hypothalamys- pituitary- thyroid gland)
  3. HPG axis (hypothalamus- pituitary- gonad)
42
Q

Secretion of a. hormone is stimulated or inhibited by a change in what?

A

the leve lof a specific extracellular signal.

43
Q

What HIGHLY regulates the first tier (hypothalamus) of the endocrine axes?

A
  • Neural inputs from the
      1. Suprachiasmatic nucleus (SCN)- sets a circadian rhythm on the secretion of hypothalamic releasing hormones and endocrine axes
      1. Pineal gland- releases melatonin, which tells the SCN about day/night
  • Stress
44
Q

To respond, a target tissue must have what?

A

receptors for the specific hormone

45
Q

The responsiveness of a target tissue to a hormone is expressed in the ____________

A

Dose-response relationship: the magnitude of our response is related to the concentration of the hormone. As the concetration increases, response increases bc more likelihood of binding and then levels off d/t saturation

46
Q

What is sensitivity (EC50) defined as?

A

The hormone concentration that produces 50% of the maximal response. If more hormone is needed to produce 50% of the maximal response, then there is a target. tissue is LESS sensitive. If less is required, tissue is MORE sensitive.

47
Q

How can we change responsiveness of a tissue to a hormone?

A

Upregulate or down-regulate by altering

    1. the number of receptors.
    1. the affinity of the receptor for the hormone.
48
Q

A change in the number or affinity of receptors is called _________.

A

Up-regulation or down-regulation.

49
Q

What is the difference between up-regulation or down-regulation?

A

Upregulation means that we increase the number of receptors or sensitivity of the target tissue when hormone levels are low by [making new ones, decrease degradation of existing ones or activating receptors].

Downregulation means that we decrease the number of receptors or sensitivity of target tissue when hormones are high for a while.

50
Q

What are the 3 major mechanisms hormones act on target cells?

A
  1. Adenylyl cyclase, where cAMP is the second messenger.
  2. Phospholipase C, where IP3/Ca2+ is the second messenger
  3. Guanylate cyclase, in which cGMP is the second messenger.
51
Q

Describe how hormones act via the adenyl cyclase mechanism.

A
  1. The 1st messenger aka hormone (ACTH, LH, FSH, TSH and glucagon), bind to a receptor coupled to a Gs or Gi protein.
  2. G-protein activates or inhibits the primary effector, adenylyl cyclase.
  3. If activated, AC converts ATP–> cAMP, the second messenger.
  4. cAMP activates PKA, the seoncdary effector, which phosphorylates proteins and causes physiologic actions.
  5. When inactivated: cAMP–> 5’ AMP.
52
Q

Describe how hormones act via the phospholipase C mechanism.

A
  1. 1st messenger hormone (GnRH, TRH and oxytocin) binds to a GCPR in the cell membrane bound to Gq G-protein.
  2. Gq protein binds and activates phospholipase C, the primary effector.
  3. PLC–> PIP2–> DAG and IP3 (2nd messengers)
  4. IP3 causes the release of Ca2+ (2nd messenger) from endoplasmic or sarcoplasmic reticulum.
  5. Ca2+ and DAG activate PKC/calmodulin (secondary effector), which phosphorylates proteins
  6. Final physiologic action is made.
53
Q

Describe how hormones act via the steroid hormone receptor.

A

Steroid hormones diffuse through the cell membrane and bind to cystolic or nuclear receptors that cause transciption/synthesis of proteins. There are no secondary messengers.

54
Q

What do steroid hormone receptors look like?

A

Monomeric phosphoproteins with 6 domains (A-F).

  • Steroids bind to the E domain
  • C domain is highly conserved with 2 zinc fingers and is where DNA binds.
55
Q

Describe the steps involved in steroid hormone MOA.

A
56
Q

Some hormones bind to cell surface receptors that have, or are associated with enzymatic activity on intracellular side of the cell membrane. These are called ____________ receptors and include what?

A

Catalyic receptors

they include guanylyl cyclase, serine/threonine kinase, tyroine kinases, tyrosine-kinase assx receptors.

57
Q

How does the catalytic receptor guanylyl cyclase work?

A
  1. First messenger hormones (ANP, NO) bind to the extracellular domain of the receptor.
  2. NO diffuses into the cytosol, activating the intracellular domain guanyl cyclase (primary effector)
  3. GTP–> cGMP (2nd messenger)
  4. Activates PKG, the secondary effector.
58
Q

There are two types of tyrosine kinases: receptor tyrosine kinases and tyrosine kinase-associated receptors. What is a receptor tyrosine kinase?

A
  • -Has extrinsic binding spot and intrinsic tyrosine kinase.
  • When activated, the intrinsic tyrosince kinase phosphorylates itself and other proteins. Example: growth factor and epidermal growth factor receptors.
59
Q

There are two types of tyrosine kinases: receptor tyrosine kinases andtyrosine kinase-associated receptors. What is a tyrosine kinase-associated receptor?

A

Noncovalently associate to proteins that have tyrosine kinase activity.

60
Q

A shorter protein binding % means what

A

It can exert its effects quicker; only. unbound protein can exert effects

Endo/Repro Exam 1 (14 decks)

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