Ch. 16 Flashcards
Define hormone
Chemical substance produced and released by endocrine cells
Define endocrine gland
Discrete endocrine organ
Define paracrine
Locally-acting chemical signal that binds to receptors and exerts a regulatory effect on cells in the neighborhood of the cell that released it
Define autocrine
Chemical signal that acts within the same cell that released it
Define steroid
A hormone derived from dietary cholesterol
Define peptide hormone
A hormone derived from assemblages of amino acids
Define amine hormone
A hormone derived from a specific amino acid
Define catecholamine
Amine hormone derived from tyrosine; structure of only one benzene (i.e., dopamine, epinephrine)
Define iodothyronine
Amine hormone derived from tyrosine; structure of two benzenes (i.e., thyroxine, triiodothyronine)
Define neurohemal organ
Organ made up of axon terminals of neurosecretory cells in association with a well-developed bed of capillaries or other circulatory specializations, in which the axon terminals store neurohormones and secrete them into the blood (i.e., pituitary gland)
Define the two parts of the pituitary gland.
- Adenohypophysis (anterior lobe): non-neural origin
- Neurohypophysis (posterior lobe): neural origin
Define vasopressin (ADH)
Posterior pituitary hormone produced by most mammals that regulates water balance in the body (i.e., urine volume)
Define oxytocin
Posterior pituitary hormone produced by most mammals that regulates reproduction (i.e., uterus contraction) and social behaviors
Define tropic hormones
Hormones produced by the anterior pituitary that control endocrine tissue (i.e., ACTH -> adrenal cortex)
Define directing acting
Hormones produced by the anterior pituitary that control non-endocrine tissue (i.e., prolactin -> mammary glands)
Define synergism
One hormone amplifies the effect of another
Define antagonism
One hormone opposes the action of another
Define permissiveness
One hormone is required for action of another
Explain why negative feedback is necessary in the endocrine system.
Some hormones can be stable for days, so negative feedback needs to be in place to stop certain reactions/binding from happening.
Define HPA axis
Hypothalamus-pituitary-adrenal axis
(1) CRH and vasopressin produced by hypothalamus
(2) ACTH produced by anterior pituitary
(3) Glucocorticoids produced by adrenal cortex
(4) Target tissues: muscle, bone, liver, adipose tissue, immune system, vasoconstriction
Define CRH
Corticotropin-releasing hormone
Define ACTH
Adrenocorticotropic hormone
Define adrenal gland
The endocrine organs located behind the kidneys
Define glucocorticoid
Steroid hormones produced from the cortex of adrenal glands
Define insulin
Pancreatic hormone that promotes glucose storage and reduces blood glucose levels
Define glucagon
Pancreatic hormone. that promotes glucose release from storage and elevated blood glucose levels
Define ectocrine
Chemical signal that acts outside the body (i.e., pheromones, kairomones)
Melatonin is a _______________ (type of hormone) derived from __________________.
amine, tryptophan
What types of hormones are lipid-soluble?
Steroids and amine hormones produced by the thyroid gland
Lipid solubility allows what type of secretion into cells?
Simple diffusion through lipid bilayer
Define the half life of a hormone
Survival time after release
Name the four ways a hormone can enter a cell
- Intracellular receptors
- G protein-coupled receptors
- Enzyme-linked receptor
- Simple diffusion
Which pituitary lobe has neural origins?
Posterior
Which pituitary lobe has non-neural origins?
Anterior
Describe the mechanism of transduction in the posterior pituitary.
Neurons directly stemming from the hypothalamus extend through the posterior lobe. Hormones are released into the bloodstream.
Describe the mechanism of transduction in the anterior pituitary.
Neurons stemming from the hypothalamus immediately release hormones into portal vessels, which carry into the anterior lobe. These hormones stimulate different hormone production within the anterior lobe, which re-enter the bloodstream for outflow.
How does increased insulin impact the blood glucose?
Decreased blood glucose (increased storage)
How does insulin and glucagon interact and impact blood glucose?
Antagonistic; no effects on BG when compared to only insulin
How does insulin and epinephrine interact and impact blood glucose?
Epinephrine increases BG slightly since glucose is needed in fight/flight stimulated by epinephrine (adrenaline).
How does insulin, glucagon, and epinephrine interact and impact blood glucose?
Since glucagon and epinephrine are synergistic, they act against insulin and increase the BG.
After a high-carb meal, glucagon concentration is ________ and insulin concentration is ___________.
low, high
After a high-protein meal, glucagon concentration is ________ and insulin concentration is ___________.
high, low
Why does glucagon concentration increase after a high-protein meal?
Glucose needs to be catabolized to produce enough ATP to break down and process dietary amino acids
Which organ detects ectocrines?
Vomeronasal organ
