BSI 2 Lecture 47: Endocrine 1 Flashcards
What are the major endocrine glands?
Hypothalamus, pineal gland, pituitary gland, thyroid, parathyroid, thymus, stomach, pancreas, kidney, adrenal gland, adipose tissue, small intestine, ovaries, and testes
Can hormones be secreted by non-endocrine organs?
Yes (Ex. the heart secretes ANP)
What are the three major stimuli for hormone release?
Ions or nutrients, neurotransmitters, and hormones
How does the endocrine system control certain body functions?
Via blood-borne chemical messengers called hormones
What is the name for specialized neurons that secrete directly into the blood stream rather than across a synapse?
Neuroendocrine or neurosecretory cells
Virtually all hormones are either _____ or _____.
Peptides or steroids (except for adrenaline and dopamine)
What are the four most important steroid hormones?
Estradiol, Testosterone, Cortisol, and Aldosterone
What are the four most important steroid hormones formed from?
Cholesterol
Why are steroids produced on demand and secreted directly into the bloodstream?
Because they are hydrophobic/lipophilic and can’t be stored in vesicles for calcium-mediated release
Most hormones are found in very _____ concentrations in the blood which means their receptors must be _____ affinity to be activated.
Low; high
What is a direct/short feedback loop?
When the hormone being released directly effects the gland that is secreting it. Insulin is an example of this.
What is indirect feedback in relation to hormones?
It is when the messengers feeding back are not the ones that were originally being secreted.
How are water soluble hormones (peptides and catecholamines) transported?
Dissolved in the plasma
How are steroid and thyroid hormones transported?
Bound to plasma proteins
There is an equilibrium between _____ and _____ hormone
bound; free
Which type of hormone can cross the cell membrane?
Free
When free hormones cross the cell membrane and bind to an intracellular receptor, what message does this send to the kidneys?
It slows/limits clearance of hormones from the plasma by the kidneys
What two factors determine the level of hormone in the blood?
Rate of secretion vs. rate of removal
How are hormones cleared from the body?
Metabolism, tissue binding, excretion by the liver via bile, and excretion by kidneys via urine
True or false? Most cells are constantly exposed to a “cocktail” of various chemical messengers.
True
What are the two principle methods for estimating hormone levels?
Radioimmunoassay (RIA) and Enzyme-linked immunosorbent assay (ELISA)
Which test (RIA or ELISA) replaced the other and why?
ELISA replaced RIA because there is no radioactivity in the ELISA test
