Ch. 5: The Endocrine System Flashcards
what are the organs of the endocrine system
glands
what do glands secrete
hormones
definition of hormones
signaling molecules that are secreted directly into the bloodstream to distant target tissues
what are peptide hormones made of
long chains of amino acids, polypeptide sequences
how are peptide hormones released from the cell
- packaged into vesicles
- released via exocytosis
- through plasma membrane d/t polarity/charge
what is the first messenger in the signaling cascade
the peptide hormone that binds to an extracellular receptor and triggers the transmission of a second signal
what is the second messenger in the signaling cascade
the signal that is released by the first messenger
amplification
an increase in signal intensity d/t either one hormone binding to many receptors (first step) or one receptor activating multiple enzymes (second step)
what is the timeline of the effect of a peptide hormone
rapid but short-lived d/t the transient nature of second messenger cascades
how do peptide hormones travel in the bloodstream
freely because they are polar and therefore water soluble
what are steroid hormones made of
cholesterol derivatives
how are steroid hormones released from the cell
pass freely because they are nonpolar
where are steroid hormone receptors located
intracellular or intranuclear
where are peptide hormone receptors located
on the surface
dimerization
pairing of two receptor-hormone complexes
what effect do steroid hormones have on DNA
bind directly to DNA causing conformational changes and increasing or decreasing transcription of particular genes
what is the timeline of the effect of a steroid hormone
effect is slower but longer-lived because of the effect on gene regulation
how do steroid hormones travel in the bloodstream
they are carried by proteins because they are nonpolar
how do steroids function while attached to proteins
proteins are inactive while attached to carrier proteins and must dissociate in order to function
what are amino-acid derivative hormones made of
one or two amino acids with additional modifications
what is the timeline of the effect of an amino-acid derivative hormone
highly unpredictable
epinephrine and norepinephrine are fast
thyroxine is long
how do direct hormones act on target tissues
directly
how do tropic hormones act on target tissues
via an intermediary
what are the eight hormone glands
- hypothalamus
- pituitary
- thyroid
- parathyroid
- adrenal
- pancreases
- gonads
- pineal
the hypothalamus bridges what two systems
endocrine and nervous systems
how does the hypothalamus control the pituitary
through paracrine release of hormones into a portal system that connects them
the hypothalamus is regulated by what type of feedback
negative feedback
hypophyseal portal system
blood vessel connecting the hypothalamus and the anterior pituitary
axes
three-organ systems involved in hormone feedback systems
how does the hypothalamus control the posterior pituitary
hypothalamus axons extend directly into the posterior and release oxytocin and antidiuretic hormone
what are the products of the anterior pituitary
FLAT (tropic) PEG (direct)
Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Adrenocorticotropic hormone (ACTH) Thyroid-stimulating hormone (TSH) Prolactin Endorphins Growth hormone (GH)
what feedback systems regulates oxytocin release
a positive feedback system
contractions stimulate stronger contractions
what does prolactin do
stimulates milk production in the mammary glands
what do endorphins do
decrease perception of pain
what do growth hormones do
promote growth of bone and muscle by
- preventing glucose uptake in non-growing tissues
- stimulating breakdown of fatty acids
which allow growth to occur at epiphyseal plates
what does antidiuretic hormone do
increases reabsorption of water in the kidneys by increasing the permeability of the collecting duct to water
what does oxytocin do
stimulates uterine contractions in labor and milk letdown during lactation
what does thyroid-stimulating hormone do
controls the two major functions of the thyroid
- setting basal metabolic rate
- promoting calcium homeostasis
what do triiodothyronine and thyroxine do
adjust basal metabolic rate by making energy production more or less efficient
what do thyroid follicular cells produces
T3, T4, and C-cells
what do C-cells produce
calcitonin
what does calcitonin do
tones down calcium levels in the blood
- IGNORE decreases gut absorption of calcium
- STORE increases calcium storage in the bone
- WASTE increases kidney excretion of calcium
what does parathyroid hormone do
- increases blood calcium levels (opposite of calcitonin)
also. ..
- promotes phosphorous homeostasis
- activates vitamin D
what does the adrenal cortex secrete
corticosteroids (SUGAR, SALT, SEX)
what do glucocorticoids do
regulate glucose levels (SUGAR)
- cortisol
- cortisone
what do mineralocorticoids do
maintain salt and water homeostasis (SALT)
- aldosterone
what are cortical sex hormones
androgens and estrogens
what does the adrenal medulla secrete
epinephrine and norepinephrine
where are the islets of langerhans cells located
in small clusters throughout the pancreas
what cell secretes glucagon and when
islet alpha cells when glucose is low
what cell secretes insulin and when
islet beta cells when glucose is high
what cell secretes somatostatin and when
islet delta cells when glucose and amino acid concentrations are high (inhibits glucagon and insulin)
what secretes melatonin
the pineal gland
