Endocrine System Flashcards
How are hormones transported?
through the circulatory system
What two systems regulate and coordinate distant organs?
endocrine and nervous system
______ mainly controls activities that involve slower, longer-acting responses that may persist for hours, weeks, months, or even years
the endocrine system
What are the four types of cell signaling that occur in the endocrine system?
classical endocrine signaling, neuroendocrine signaling, paracrine regulation, and autocrine regulation
Classical endocrine signaling
hormones are secreted into the extracellular fluid by ductless endocrine glands, and circulate throughout the body in blood
Only _______ of a hormone, those with receptor proteins that recognize and bind that hormone, respond to it- the hormones may either speed up or inhibit cellular processes
target cells
Hormones are cleared from the body at a steady rate by enzymatic breakdown, where?
target cells, liver, or kidneys
In neuroendocrine signaling, specialized neurons called _______ release a neurohormone
neurosecretory neurons
The neurohormone is distributed by the ________ and elicits a response in target cells that have receptors for the hormone
circulatory system
Paracrine regulation
a cell releases a signaling molecule that diffuses through the ECF and acts on nearby cells (regulation is LOCAL)
Autocrine regulation
the local regulator acts on the same cells that produced it
What are the four classes of hormones and local regulators?
amine hormones, peptide hormones, steroid hormones, and fatty acid derived molecules
Amine hormones are involved in _______ and _________
endocrine and neuroendocrine signaling
Dopamine, epinephrine, norepinephrine, and thyroxine are examples of…
amine hormones
Most amine hormones are based on ______
tyrosine
Peptide hormones are involved in classical ________ and __________
endocrine signaling and neuroendocrine signaling
What is an example of a peptide hormone?
growth factor
Growth factors
regulate division and differentiation of many cell types; act in paracrine and autocrine signaling
What type of signaling are steroid hormones involved in?
classical endocrine signaling
Steroid hormones are derived from?
cholesterol
What are types of steroid hormones?
aldosterone, cortisol, sex hormones
What types of signaling are fatty acid derived molecules involved in?
paracrine and autocrine
What is an example of a fatty-acid-derived molecule?
prostaglandins
The secretion of many hormones is regulated by negative feedback pathways- which means?
a product of the pathway inhibits an earlier step in the pathway
The hypothalamus secretes _____
thyroid-releasing hormone
in response to the thyroid-releasing hormone, the pituitary releases _________, which stimulates the thyroid gland to release thyroid hormones
thyroid-stimulating hormone
Increasing thyroid hormone concentration in the blood inhibits thyroid-stimulating hormone secretion by the ________
pituitary
There are four hormone groups that keep fuel levels in balance; what are they?
insulin and glucagon, growth hormone, epinephrine and norepinephrine, and glucocorticoid hormones
Insulin and glucagon are secreted by…
the pancreas
growth hormone is secreted by ______
the anterior pituitary
epinephrine and norepinephrine are released by _______ and _______
the sympathetic nervous system; adrenal medulla
glucocorticoid hormones are released by_______
the adrenal cortex
Hormones control cell function by…
binding to receptor molecules in their target cells
small quantities of hormones can produce profound effects by _____, in which each activated protein activates a larger number of proteins for the next step in the pathway
amplification
__________ steroid and thyroid hormones pass through the plasma membrane and bind to internal receptors in the nucleus or cytoplasm
hydrophobic (can freely pass through plasma membrane)
Can hydrophobic or hydrophilic hormones pass the membrane?
hydrophobic
What is the function of aldosterone?
increases Na1 reabsorption in the kidneys when concentration of the ion falls in the blood
in mammals, epinephrine can bind to several different G-protein-coupled receptors known as _______
adrenergic receptors
hypothalamus
region of the brain located in the floor of the cerebrum
pituitary gland
consisting of two fused lobes, is suspended below the hypothalamus by a stalk of tissue
posterior pituitary
contains axons and nerve ending of neurosecretory neurons that originate in the hypothalamus
anterior pituitary
contains nonneuronal endocrine cells that form a distinct gland
Secretion of hormones from the anterior pituitary is controlled by peptide neurohormones called ______ and _____, which are released by the hypothalamus
releasing hormones, inhibiting hormones
Releasing hormones and inhibiting hormones are carried in the blood from the hypothalamus to the anterior pituitary in a _____ that provides a critical link between the brain and the endocrine system
portal vein
What is the function of releasing hormones and inhibiting hormones?
they regulate the anterior pituitary’s secretion of hormones that control other endocrine glands and processes
How many hormones does the anterior pituitary secrete into the bloodstream?
8
What are the anterior pituitary hormones?
thyroid-stimulating hormone, adrenocorticotropic hormone, follicle-stimulating hormone, luteinizing hormone, prolactin, growth hormone, melanocyte-stimulating hormone, and endorphins
What are the two posterior pituitary hormones?
antidiuretic hormone and oxytocin
Thyroid-stimulating hormone
stimulates the thyroid gland to grow in size and secrete thyroid hormones
adrenocorticotropic hormone
triggers hormone secretion by cells in the adrenal cortex
follicle-stimulating hormone
controls egg development and secretion of sex hormones in female mammals, and sperm production in males (maturation)
luteinizing hormone
regulates part of the menstrual cycle in human females and the secretion of sex hormones in males
follicle-stimulating hormone and luteinizing hormone are both…
gonadotropins (they regulate the activity of the gonads)
Prolactin
influences reproductive activities and parental care in vertebrates; stimulation of mammary glands during suckling leads to prolactin release
growth hormone
stimulates cell division, protein synthesis, bone growth; binds to target tissues causing them to release insulin-like GF
endorphins
acts as a neurotransmitter in PNS that controls pain- inhibiting the perception of pain
antidiuretic hormone
stimulates kidney cells to absorb more water from urine, increasing volume of blood; released when the hypothalamus detects an increase in the blood’s osmotic pressure during periods of dehydration
oxytocin
stimulates ejection of milk of mammary glands; release is triggered by suckling, which sends neuronal signals to the hypothalamus; stimulates more oxytocin secretion by a positive feedback mechanism
What are the seven major endocrine glands or tissues?
thyroid gland, parathyroid, adrenal medulla, adrenal cortex, gonads, pancreas, pineal gland
thyroid gland
located in the front of the throat in humans, is shaped like a bowtie
the thyroid gland secretes the iodine-containing hormones __________ and _________
thyroxine (T4) and triiodothyronine (T3); in the cell most T4 get converted to T3
T3 triggers _____ in amphibians
metamorphosis
hypothyroidism
slows mental and physical processes
hyperthyroidism
produces nervousness and emotional instability, insomnia, weight loss, and a rapid and irregular heartbeat
The most common form of hyperthyroidism is ________
Graves’ disease (characterized by inflamed, protruding eyes)
Insufficient ____ in the diet can cause enlargement of the thyroid
iodine
in mammals, the thyroid has specialized cells that secrete the peptide hormone _____, which lowers the level of Ca2+ in the blood by inhibiting release of calcium from bone
calcitonin
Mammals have four _______ located on the posterior surface of the thyroid gland, two on each side
parathyroid glands
parathyroid glands secrete _________ in response to a fall in blood Ca2+ levels
parathyroid hormone
parathyroid hormone stimulates enzymes in the kidneys that convert ______ into its active form, increasing absorption of Ca2+ and phosphates from ingested food and releasing of Cq2+ from bone in response to PTH
vitamin D
underproduction of parathyroid hormone causes ____ to fall, disturbing nerve and muscle function
Ca2+ concentration
overproduction of parathyroid hormone results in ________
loss of calcium from bones and deposition in soft tissues (lungs, arteries, and kidneys)
