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20 Cards in this Set

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  • Back
How does the secretion of exocrine substances differ from that of endocrine substances?
Exocrine substances are secreted into a duct; endocrine into the circulatory system
Define permissiveness.
A second hormone is necessary for the first hormone to have any effect.
Define potentiation.
To enhance the effects of another substance.
List the hormones we have studied, where they are produced, and their major functions.
Aldosterone: steroid
Epi and Norepinephrin: amines
Gastrin: peptide
Secretin: peptide
CCK: peptide
Motilin: peptide
Vasopressin: peptide
Angiotensin II: peptide
What hormones are hydrophilic, and which are hydrophobic?
Hydrophilic: catecholamines and peptides
Hydrophobic: T4/T3 amines and steroids
What determines what hormone a precursor molecule will become?
The presence of enzymes to convert to another hormone
How are peptide hormones synthesized?
Synthesized on the RER, where peptidases in the RER lumen cleave it from a preprohormone to a prohormone. Vesicles bud to the Golgi.
Packaged in the Golgi, where a series of enzymes cleave the prohormone into a hormone.
Stored in secretory vesicles as a hormone.
Secreted into the internal system
Describe steroid hormones.
Derived from cholesterol. Immediately diffuse across the plasma membrane upon synthesis. Receptors are typically in the cytosol and serve as transcription factors. Tends to be slower than transmembrane receptors because they change gene expression.
How are steroid hormones synthesized and secreted?
1) A peptide hormone signals the synthesis of the steroid hormone through g-protein coupled receptor mechanism.
2) pKA phosphorylates targets including cholesterol esterase.
3) Cholesterol is stored as lipid droplets
4) Free cholesterol is used and shuffled between the SER and the mitochondria
How is aldosterone secreted?
Binding of Angiotensin II activates a signaling cascade. Aldosterone is synthesized in the adrenal cortex.
What allows peptide response to be so quick?
1 first messenger might activate hundreds of cAMP, 100s of pka, 10,000 enzymes, and millions of phosphorylated enzymes...
What are the regions of the adrenal gland, and what is synthesized in each?
Medulla (epinephrin & norepinephrin)
Cortex (aldosterone, ???)
What is the hypothalamus part of in the brain?
Part of the diencephalon
Where is the primary capillary bed of the hypothalamus located?
In the infundibular stem
What are the hormones released into the primary capillary bed called?
Tropic hormones: cause the release of more hormones
What is the function of thyroid hormone?
Upregulation and synthesis of beta-adrenergic receptors for epinephrine
What are the effects of increased plasma cortisol during stress?
1) Organic metabolism: break down proteins to make amino acids available as an energy source; maintains high glucose levels; break down triglycerides
2) Increased ability to maintain vasoconstriction in response to norepinephrine and other stimuli
3) Protective effects against the damaging influences of stress
4) Inhibition of inflammation and specific immune responses
5) Inhibition of nonessential functions (reproduction and growth)
List the hypothalamic hormones and the pituitary hormones they regulate.
GnRH: LH/FSH: Estrogen/testosterone
GHRH/SS: Growth hormone (IGF-1 in the liver; protein synthesis, carb and lipid metabolism)
TRH: TSH: Stimulates secretion of thyoxine and triiodothyrine (thyroid)
DA: Prolactin
CRH: ACTH: Cortisol (adrenal)
What functions do steroid binding proteins have?
Maintain a stable high concentration of the hormone in the plasma and reduce its clearance rate from plasma
Reduce the binding of the hormone to its receptors in some cases
Make the hormone more soluble in aqueous plasma
Is the adenohypophysis a neural tissue?
Yes. It is stimulated by action potentials in the hypothalamus.