HORMONES Flashcards
Hydrophilic hormone properties
- Derived from amino acids and glycoproteins
- High concentration in bloodstream
- Do not require carrier proteins
- Bind to membrane proteins for signaling
*Exception: IGF-1 hormone uses a carrier protein
Hydrophobic hormone properties
- Use carrier proteins for transport
- Longer half-lives
- Most bind to internal receptors
*exception: eicosanoids have receptors on cell membrane surface
Steroids: Cholesterol derivatives (5)
Structural properties of cholesterol: 4 rings
- Glucocorticoids: Cortisol & corticosterone
- Mineralocorticoids: Aldosterone & deoxycorticosterone
- Progestins: Progesterone
- Androgens: Testosterone & dihydrytestosterone
- Estrogens: Estradiol, estrone, estriol
*specificity due to hydroxyl groups
*Synthesized in ER or mitochondria
*rate of synthesis controls levels
Steroid: Cortisol
- Glucocorticoid, 21 C (most similar to cholesterol)
- Gluconeogenesis & stress response
- Lung development
- Made in adrenal cortex
- Binds to CBG in serum

Steroid: Aldosterone
- 21 C; aldehyde at C18
- Involved in salt/water balance

Steroid: Progesterone
- 21 C; double bond or hydroxyl at C3, double bond at C4, Lacks hydroxyl at 11, 17, 21, side chain at C21 removed
- Important in pregnancy

Steroid: Testosterone (DHT)
- 19C Lacks side chain at C17
- Main male sex hormone: genital development, secondary characteristics
- Aggression (males and females)
- Bone maintenance

Steroid: Estradiol
- 18C; aromatic A ring; lose side chain at C19
- Female sex tissue function
- Male brain development
- Male fertility
- Bone maintenance
- Cardiovascular protection

Vitamin D: cholesterol derivative
- 3 ring structure: lysosteroid
- 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)
- Ergosterol found in plants –> active Vit D
- Main fxn: increase calcium absorption from intestine & bone development & cell differentiation

Vitamin D diseases
- Rickets: lack of Vit D3
- bones, bow legs, knocked knees
- extreme form: lacking VitD3 receptors
- Symptoms: no hair development & malformed teeth
Retinoids
- Derived from beta carotene (Vitamin A)
- Cleaved to form retinaldehyde -
All-Trans retinoic acid binds retinoid acid receptor
* Controls growth and differentiation -
9-cis retinoic acid binds retinoid X receptor
* Forms heterodimers w/ other receptors

Thyroid Hormones
- T3 & T4 (thyroxine); iodonated tyrosines; T3=active form
- Linked to growth hormone
- Important in brain development
- Partially lipid soluble
- Modulate transcription
- Set metabolic rate
- Binds to carrier proteins
*Circulating levels controlled by release

Thyroid diseases
- Cretinism: thyroid hormone deficiency since birth
- Mental retardation
- short stature - Goiter
Protein & Peptide hormones (3)
- Growth hormone
* 2 polypeptide bonds; 1 disulfide - Insulin
- 2 polypeptide bonds; 2 disulfide
- IGF-1 (insulin growth factor) binds to carrier proteins
- Somatostatin (peptide)
* 14AA, inhibitory hormone
*Synthesized on rough ER and golgi; stored in secretory vesicles
*Control circulating levels by release
*Made as a precursor
Glycoprotein hormones (4)
- Luteinizing hormone (LH)
* Anterior pituitary - Thryoid Stimulating Hormone (TSH)
* Anterior pituitary - Follicle Stimulating Hormone (FSH)
* Anterior pituitary - Chorionic gonadotropin (HcG)
* Placenta - alpha subunit is the same for all; beta subunit confers specificity
- All activate cAMP
Catecholamines: AA derivatives
- 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
- Glucocorticoids from adrenal cortex increase synthesis of DBH in adrenal medulla
- PNMT (phenylethanolamine-N-methyltransferase) converts NE –> E
- Degraded by COMT and monoamine oxidase
- Pheochromocytomas: tumors of adrenal medulla that overproduce NE & E
- Increase ATCH production
Eiconasoids
- Hyrdophobic
- Derived from arachidonic acid
* PGH2 is precursor to thromboxane & prostaglandins - Bind to membrane receptors (usually G protein coupled)
- Paracrine and possibly autocrine effects
- COX inhibited by aspirin
*Synthesized in membranes, very short half-life
- Endocrine signaling
- Paracrine signaling
- Autocrine signaling
- Hormone is produced –> enters blood stream –> acts upon target tissue (Vit D kidney –> intestine)
- Hormone is created close to target tissue –> acts locally (Testosterone testes –> seminiferous tubules)
- Hormone is produced by same cell it acts on (growth hormone & prostaglandins)
Homeostasis
- Hormone requires cells to have receptors for regulating hormone
- 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
Hormone Testing (2)
- Radioimmunoassay
- Radioactive version of hormone miced with non
- Standard curve to compare radioactive counts to determine how much hormone present in sample
- 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
Hormones secreted in active form (5)
(CHEAT)
- Hydrocortisone
- Aldosterone
- T3
- Estradiol
- Catecholamines
Hormones activated peripherally in target tissue (3)
(TTT)
- Thyroxine –> T3
- Testosterone –> dihydroxytestosterone
- testosterone –> 17ß-estradiol
Carrier protein properties
- Reservoir: protect against degradation
- Act as a buffer to prevent surges in levels
- For steroids, bnd with low affinity, high capacity. Bind with high affinity to IGFs