Chapter 45: Hormones and the Endocrine System Flashcards
Define endocrine signaling
secreted molecules diffuse into the bloodstream and trigger responses in target cells anywhere in the body
Define paracrine signaling
secreted molecules diffuse locally and trigger a response in neighboring cells
Define autocrine signaling
secreted molecules diffuse locally and trigger a response in the cells that secreted
Define synaptic signaling
NTs diffuse across synapses and trigger responses int arget tissues
Define neuroendcorine signaling
neurohormones diffuse into the blood stream and trigger responses in target cells anywhere in the body
What are local regulators?
molecules that act over short distances, reach target cells SOLELY by diffusion, and act on target within mili/seconds
Prostaglandins are produced _____. They are a type of local regulator.
Throughout the body
How does nitric oxide act as a local regulator?
NO is a gas.
When the level of oxygen in the blood falls, endothelial cells release NO, which diffuses into muscle cells and relaxes the cells. Vasodilation
The three major chemical classes of hormones are __,____, and ____. Their solubility is ….
Polypeptides (water soluble/hydrophilic), steroids (lipid soluble/hydrophobic), and amines (both)
Compare the location of receptor proteins in target cells for water-soluble hormones to lipid-soluble
water-soluble: secreted by exocytosis and travel freely in the bloodstream, bind to cell-surface receptors
lipid: diffuse via diffusion and bind to transport proteins. Diffuse into target cells and bind to receptors in the cytoplasm or nucleus.
How do response mechanisms in target cells differ for
water-soluble and lipid-soluble hormones?
Water-soluble hormones, which cannot penetrate the plasma membrane,
bind to cell-surface receptors. This interaction triggers an intracellular signal
transduction pathway that ultimately alters the activity of a preexisting protein
in the cytoplasm and/or changes transcription of specific genes in the nucleus.
Steroid hormones are lipid-soluble and can cross the plasma membrane into the
cell interior, where they bind to receptors located in the cytosol or nucleus. The
hormone-receptor complex then functions directly as a transcription factor that
changes transcription of specific genes
The thyroid is responsible for
stimulates and maintains metabolic processes
lowers blood calcium level
The parathyroid is responsible for
Raises blood calcium level
The adrenal medulla is a type of adrenal gland responsibel fro
epinephrine and norepinephrine
The adrenal cortex is a type of adrenal gland responsible for
glucocorticoids (BGL)
mineralocorticoids reabsorb Na_ and excrete K+ in kidneys
The ovaries are responsible for
secreting estrogen and progesterone
The testes are responsible for
secretion of androgens
The pineal gland is responsible for
production of melatonin
The hypothalamus is responsible for
regulating the anterior pituitary
Hormones released from the posterior pituitary as well
The posterior pituitary is responsible for
oxytocin
vasopression/ADH
The anterior pituitary is responisble for
FSH/LH: stimulate gonads
thyroid stimulating hormone
Adrenocorticiotropic hormone
Prolactin
Growth hormone
MSH
The pancreas is responsible for
insulin and glucagon
Define a simple endocrine pathway
cells respond directly to a stimulus by secreting a hormone
Hormone travels through the bloodstream to target cells
Define a simple neuroendocrine pathway
stimulus is received by a sensory neuron rather than endocrine tissue
Negative feedback can be defined as
the response reduces the initial stimulus
positive feedback can best be defined as
a stimulus is reinforced
Compare the posterior and anterior pituitary
posterior: extension of the hypothalamus
anterior: an endocrine gland that synthesizes and secretes hormones in response to hypothalamus hormones
Antidiuretic hormone, or vasopressin is responsible for…. and produced in the ____
responsible for regulating kidney function
produced in posterior pituitary
Prolactin is responsible for …. and produced in ___
stimulates milk production
anterior pituitary hormones
Growth hormone is secreted by ____ and responsible for
anterior pituitary
stimulates growth
What are the roles of oxytocin and prolactin in regulating
the mammary glands?
Prolactin regulates milk production, and oxytocin regulates milk release.
How do the two fused glands of the pituitary gland differ in
function?
The posterior pituitary, an extension of the hypothalamus that contains
the axons of neurosecretory cells, is the storage and release site for two neuro-
hormones, oxytocin and antidiuretic hormone (ADH). The anterior pituitary
contains endocrine cells that make at least six different hormones. Secretion of
anterior pituitary hormones is controlled by hypothalamic hormones that travel
via blood vessels to the anterior pituitary.
Propose an explanation for why defects in a par-
ticular hormone cascade pathway observed in patients typi-
cally affect the final gland in the pathway rather than the
hypothalamus or pituitary
The hypothalamus and pituitary
glands function in many different endocrine pathways. Many defects in these
glands, such as those affecting growth or organization, would therefore disrupt
many hormone pathways. Only a very specific defect, such as a mutation affect-
ing a particular hormone receptor, would alter just one endocrine pathway. The
situation is quite different for the final gland in a pathway, such as the thyroid
gland. In this case, a wide range of defects that disrupt gland function would dis-
rupt only the one pathway or small set of pathways in which that gland functions
When blood Ca2+ level galls below a set point, ___ glands release___ hormone
parathyroid glands
PTH
How does PTH raise the level of blood Ca2+ in bones, kidneys, and intestines?
direct effects in bones and kidneys, indirect on intestines
bones: PTH causes matrix to break down
Kidneys: stimulates reabsorpition through renal tubules
Intestines: promotes production of vitamin D, which helps stimulate calcium in food
If the blood Ca2+ level rises above the set point, the thyroid gland releases ____, which acts by…
calcitonin
inhibits bone breakdown and enhances Ca2+ excretion in kidneys
List the effects of epinephrine and norepinephrine, as well as where they are produced
produced in adrenal medulla
glycogen broken down to glucose
increase BP, RPM, metabolic rate
change in blood flow patterns
Describe the effect of minerlocorticoids and where they are produced
adrenal cortex
retention of sodium ions and water
increased blood volume and blood pressure
Describe the effect of glucocorticoids and where they are produced
adrenal cortex
proteins and fats broken down and converted to glucose
suppression of immune system
If a hormone pathway produces a transient response to
a stimulus, how would shortening the stimulus duration
affect the need for negative feedback?
. If the function of the pathway is to provide a transient response, a short-lived
stimulus would be less dependent on negative feedback
Suppose you receive an injection of cortisone, a
glucocorticoid, in an inflamed joint. What aspect of gluco-
corticoid activity would you be exploiting? If a glucocorti-
coid pill were also effective at treating the inflammation,
why would it still be preferable to introduce the drug
locally?
You would be
exploiting the anti-inflammatory activity of glucocorticoids. Local injection
avoids the effects on glucose metabolism that would occur if glucocorticoids
were taken orally and transported throughout the body in the bloodstream.
Which statement is accurate?
(A) Hormones that differ in effect reach their target cells by
different routes through the body.
(B) Pairs of hormones that have the same effect are said to
have antagonistic functions.
(C) Hormones are often regulated through feedback loops.
(D) Hormones of the same chemical class usually have the
same function
Hormones are often regulated through feedback loops.
The hypothalamus
(A) synthesizes all of the hormones produced by the pituitary
gland.
(B) influences the function of only one lobe of the pituitary
gland.
(C) produces only inhibitory hormones.
(D) regulates both reproduction and body temperature.
regulates both reproduction and body temperature.
Growth factors are local regulators that
(A) are produced by the anterior pituitary.
(B) are modified fatty acids that stimulate bone and cartilage
growth.
(C) are found on the surface of cancer cells and stimulate
abnormal cell division.
(D) bind to cell-surface receptors and stimulate growth and
development of target cells.
bind to cell-surface receptors and stimulate growth and
development of target cells.
Which hormone is correctly paired with its action?
(A) oxytocin—stimulates uterine contractions during
childbirth
(B) thyroxine—inhibits metabolic processes
(C) ACTH—inhibits the release of glucocorticoids by the
adrenal cortex
(D) melatonin—raises blood calcium level
oxytocin—stimulates uterine contractions during
childbirth
What do steroid and peptide hormones typically have in
common?
(A) their solubility in cell membranes
(B) their requirement for travel through the bloodstream
(C) the location of their receptors
(D) their reliance on signal transduction in the cell
their requirement for travel through the bloodstream
Which of the following is the most likely explanation for
hypothyroidism in a patient whose iodine level is normal?
(A) greater production of T3 than of T4
(B) hyposecretion of TSH
(C) hypersecretion of MSH
(D) a decrease in the thyroid secretion of calcitonin
hyposecretion of TSH
The relationship between the insect hormones ecdysteroid and
PTTH is an example of
(A) an interaction of the endocrine and nervous systems.
(B) homeostasis achieved by positive feedback.
(C) homeostasis maintained by antagonistic hormones.
(D) competitive inhibition of a hormone recepto
An interaction of the endocrine and nervous systems.
