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MNE > HORMONES > Flashcards

HORMONES Flashcards

1
Q

Hydrophilic hormone properties

A
  1. Derived from amino acids and glycoproteins
  2. High concentration in bloodstream
  3. Do not require carrier proteins
  4. Bind to membrane proteins for signaling

*Exception: IGF-1 hormone uses a carrier protein

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2
Q

Hydrophobic hormone properties

A
  1. Use carrier proteins for transport
  2. Longer half-lives
  3. Most bind to internal receptors

*exception: eicosanoids have receptors on cell membrane surface

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3
Q

Steroids: Cholesterol derivatives (5)

A

Structural properties of cholesterol: 4 rings

  1. Glucocorticoids: Cortisol & corticosterone
  2. Mineralocorticoids: Aldosterone & deoxycorticosterone
  3. Progestins: Progesterone
  4. Androgens: Testosterone & dihydrytestosterone
  5. Estrogens: Estradiol, estrone, estriol

*specificity due to hydroxyl groups

*Synthesized in ER or mitochondria

*rate of synthesis controls levels

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4
Q

Steroid: Cortisol

A
  1. Glucocorticoid, 21 C (most similar to cholesterol)
  2. Gluconeogenesis & stress response
  3. Lung development
  4. Made in adrenal cortex
  5. Binds to CBG in serum
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5
Q

Steroid: Aldosterone

A
  1. 21 C; aldehyde at C18
  2. Involved in salt/water balance
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6
Q

Steroid: Progesterone

A
  1. 21 C; double bond or hydroxyl at C3, double bond at C4, Lacks hydroxyl at 11, 17, 21, side chain at C21 removed
  2. Important in pregnancy
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7
Q

Steroid: Testosterone (DHT)

A
  1. 19C Lacks side chain at C17
  2. Main male sex hormone: genital development, secondary characteristics
  3. Aggression (males and females)
  4. Bone maintenance
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8
Q

Steroid: Estradiol

A
  1. 18C; aromatic A ring; lose side chain at C19
  2. Female sex tissue function
  3. Male brain development
  4. Male fertility
  5. Bone maintenance
  6. Cardiovascular protection
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9
Q

Vitamin D: cholesterol derivative

A
  1. 3 ring structure: lysosteroid
  2. Bind to VitD binding protein

3. Synthesis:

UV light (skin): 7-dehydrocholestrol –> VitD3

25 Hydroxylase (liver): VitD3 –> 25 hyrdoxyvitamin D

**1alpha-hyrdoxylase (kidney, bone, placenta): –> 1,25 hydroxyvitamin D

  • Product inhibition, high parathyroid hormone, and low serum phosphate

(Degradation pathway: 24 alpha hydroxylase)

  1. Ergosterol found in plants –> active Vit D
  2. Main fxn: increase calcium absorption from intestine & bone development & cell differentiation
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10
Q

Vitamin D diseases

A
  1. Rickets: lack of Vit D3
    - bones, bow legs, knocked knees
    - extreme form: lacking VitD3 receptors
    - Symptoms: no hair development & malformed teeth
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11
Q

Retinoids

A
  1. Derived from beta carotene (Vitamin A)
    - Cleaved to form retinaldehyde
  2. All-Trans retinoic acid binds retinoid acid receptor
    * Controls growth and differentiation
  3. 9-cis retinoic acid binds retinoid X receptor
    * Forms heterodimers w/ other receptors
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12
Q

Thyroid Hormones

A
  1. T3 & T4 (thyroxine); iodonated tyrosines; T3=active form
  2. Linked to growth hormone
  3. Important in brain development
  4. Partially lipid soluble
  5. Modulate transcription
  6. Set metabolic rate
  7. Binds to carrier proteins

*Circulating levels controlled by release

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13
Q

Thyroid diseases

A
  1. Cretinism: thyroid hormone deficiency since birth
    - Mental retardation
    - short stature
  2. Goiter
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14
Q

Protein & Peptide hormones (3)

A
  1. Growth hormone
    * 2 polypeptide bonds; 1 disulfide
  2. Insulin
  • 2 polypeptide bonds; 2 disulfide
  • IGF-1 (insulin growth factor) binds to carrier proteins
  1. Somatostatin (peptide)
    * 14AA, inhibitory hormone

*Synthesized on rough ER and golgi; stored in secretory vesicles

*Control circulating levels by release

*Made as a precursor

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15
Q

Glycoprotein hormones (4)

A
  1. Luteinizing hormone (LH)
    * Anterior pituitary
  2. Thryoid Stimulating Hormone (TSH)
    * Anterior pituitary
  3. Follicle Stimulating Hormone (FSH)
    * Anterior pituitary
  4. Chorionic gonadotropin (HcG)
    * Placenta
  5. alpha subunit is the same for all; beta subunit confers specificity
  6. All activate cAMP
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16
Q

Catecholamines: AA derivatives

A
  1. Derived from tyrosine in adrenal medulla & sympathetic/parasympathetic nervous system

Tyr –> dopa –> dopamine –> norepinephrine –> epinephrine (only made in adrenal medulla)

*1st rxn w/ tyrosine hydroxylase is rate-limiting

  1. Glucocorticoids from adrenal cortex increase synthesis of DBH in adrenal medulla
  2. PNMT (phenylethanolamine-N-methyltransferase) converts NE –> E
  3. Degraded by COMT and monoamine oxidase
  4. Pheochromocytomas: tumors of adrenal medulla that overproduce NE & E
  5. Increase ATCH production
17
Q

Eiconasoids

A
  1. Hyrdophobic
  2. Derived from arachidonic acid
    * PGH2 is precursor to thromboxane & prostaglandins
  3. Bind to membrane receptors (usually G protein coupled)
  4. Paracrine and possibly autocrine effects
  5. COX inhibited by aspirin

*Synthesized in membranes, very short half-life

18
Q
  1. Endocrine signaling
  2. Paracrine signaling
  3. Autocrine signaling
A
  1. Hormone is produced –> enters blood stream –> acts upon target tissue (Vit D kidney –> intestine)
  2. Hormone is created close to target tissue –> acts locally (Testosterone testes –> seminiferous tubules)
  3. Hormone is produced by same cell it acts on (growth hormone & prostaglandins)
19
Q

Homeostasis

A
  1. Hormone requires cells to have receptors for regulating hormone
  2. Equilibirum of total hormone bound vs unbound

*Only free hormone is active & can be degraded

*Bound hormone on carrier proteins allows for a longer half-life and resistance to degradation

20
Q

Hormone Testing (2)

A
  1. Radioimmunoassay
  • Radioactive version of hormone miced with non
  • Standard curve to compare radioactive counts to determine how much hormone present in sample
  1. ELISA
  • Well plate is coated with anitbodies specific for hormone
  • Set amount of hormone added
  • secondary antibody binds to hormone on diff epitope
  • Enzyme linked marker = color
21
Q

Hormones secreted in active form (5)

(CHEAT)

A
  1. Hydrocortisone
  2. Aldosterone
  3. T3
  4. Estradiol
  5. Catecholamines
22
Q

Hormones activated peripherally in target tissue (3)

(TTT)

A
  1. Thyroxine –> T3
  2. Testosterone –> dihydroxytestosterone
  3. testosterone –> 17ß-estradiol
23
Q

Carrier protein properties

A
  1. Reservoir: protect against degradation
  2. Act as a buffer to prevent surges in levels
  3. For steroids, bnd with low affinity, high capacity. Bind with high affinity to IGFs

MNE (16 decks)

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