Endocrine System Flashcards
Endocrine vs. Exocrine
Whats the differnce bw endocrine and exocrine glands?
- Endocrine glands secrete hormones into the blood (ductless)
- Exocrine glands secrete their products into a duct where it either enters another organ or exits the body (i.e., sweat)
pancrease has both, pituaitary gland in brain
Hormones - Released directly into blood
What are Hormones?
Chemical Messengers
What are Amine Hormones?
- Derivatives of the amino acid tyrosine
- Thyroid hormones (produced in the thyroid gland)
- Catecholamines
Amine Hormones
What are Catecholimines?
Where are they Produced?
Dopamine - Hypothalamus
Epi and NE - adrenal medulla
What are Peptide Hormones?
What is Proinsulin?
- Secreted through exocytosis
- Preprohormone -> prohormone -> active hormone
- Proinsulin cleaved to insulin and C-peptide (both active peptide hormones)
What are Steroid Hormones?
Primarily produced by adrenal cortex and gonads (ovaries and testes)
Derived from cholesterol
- Lipophilic nature allows for diffusion across cell membranes into circulation
- Typically bound to protein carriers like albumin to travel in the blood
How do the locations for steroid hormone receptors differ from peptide hormone receptors? Why?
Steroid Receptors - inside the cell becuase they can diffuse across the membrane
Peptide Receptors - found on the cell membrane, cant get across into cell due to nature
Hormone Metabolism
What does [Plasma] in the blood depend on?
The rate of secretion from the endocrine gland
The rate of removal from the blood
- Liver and kidney
- Endocytosis
- Enzymes in the blood
- Protein-bound hormones are protected
Path of a Hormone
Do hormones go to every cell?
No, Hormones have actions on only the cells that have receptors for them (allowing them to be highly specific)
Where are Peptides and Catecholamines receptors located?
receptors located on extracellular surface of target cell’s membrane (these hormones are hydrophilic)
Where are Steroid and Thyroid Hormone receptos located?
receptors are located intracellularly (these hormones are lipophilic)
alter gene expression - protein experession - cell function
What happens when a hormone binds to a receptor?
(quick and slow effects)
- Hormones bind to receptors and cause intracellular signaling cascades
- Altered enzyme activity and affected protein activity (quick effects)
- Activation or inhibition of certain genes -> change in rate of protein synthesis (slow effects)
How do Water Soluble Hormones get to a cell?
What do they do once they bine
Water - Soluble Hormone in blood unbound to any protein
Know Step 6
Hormone binds to a receptor, activating proteins and causing the function of the cell to change
How do Water inSoluble Hormones get to a cell?
- steroid hormone bound to prtoein, released and diffuses directly into the cell
- enter the nucleus and bonds to regulatory site on DNA
- Alters transcription and translation of protein,
- takes longer becasue it is creating new proteins not altering existing proteins
- ultimately changes the functions of the cell
How is hormone secretion controlled?
- Changes in [plasma] of mineral ions or organic nutrients
- Neurotransmitter release from neurons ending on endocrine cells
- Another hormone acting on the endocrine cell
Control of Hormone Secretion
How do Changes in [plasma] of mineral ions or organic nutrients affect hormone secretion?
- Major function of the hormone is to regulate the plasma concentration of the ion controlling that hormone, through negative feedback
What is an example of how hormones regulate plasma concentration of ion controlling it through negative feedback?