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92 Cards in this Set

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The pituitary gland, or ____________ , lies in a pocket (the ________ ) of the sphenoid bone at the base of the brain, Just below the brain area called the _________.
- hypophysis

- sella turcica

- hypothalamus
The pituitary is connected to the hypothalamus by the infundibulum, a stalk containing nerve fibers and small blood vessels.
-

-

-
In human beings, the pituitary is composed of ?
two adjacent lobes called the anterior pituitary (toward the front of the head; also called the adenohypophysis) and the posterior pituitary (toward the back of the head; also called the neurohypophysis).
The anterior pituitary is located where and AKA?
toward the front of the head; also called the adenohypophysis
The posterior pituitary is located where and AKA?
toward the back of the head; also called the neurohypophysis
The anterior pituitary arises embryologically from _________, while the posterior pituitary is actually
- the invagination of the pharynx called Rathke’s Pouch

-an extension of the neural components of the hypothalamus.
The axon of the two well-defined clusters of hypothalamic neurons (the supraoptic and paraventricular nuclei) pass down ?
the infundibulum and end within the posterior pituitary in close proximity to capillaries.
The the supraoptic and paraventricular nuclei do not forma synapse with other neurons. Instead, ...
their terminals end directly on capillaries.
What is the names of the two well-defined clusters of hypothalamic neurons in the pituitary gland?
the supraoptic and paraventricular nuclei
In contast to the neural connection btwn the hypothalamus and the posterior pituitary pituitary, There are ______________ btwn the hypothalamus and anterior posterior pituitary. There is, however, ___________.
- no important neural connections

-an unusual blood vessel connections.
The capillaries at the base of the hypothalamus (the median eminence) does what?
recombine to form the hypothalamo-pituitary portal vessels.
The term portal denotes blood vessels that _______.
connect two capillary beds.
What is the name of the capillaries at the base of the hypothalamus?
the median eminence
The hypothalamo-pituitary portal vessels pass down the stalk connecting _____________ and enter ____________ where they drain into ___________.
- the hypothalamus and pituitary

- the anterior pituitary

- a second capillary, bed, the anterior pituitary capillaries.
The hypothalamo-pituitary portal vessels offer? This offers the advantage of a rapid response and minimizes the amount of hypothalamic hormone that must be synthesized to reach an effective blood concentration
a local route for the blood flow directly from the hypothalamus to the anterior pituitary.
The hypothalamo-pituitary portal vessels offers the advantage of?
a rapid response and minimizes the amount of hypothalamic hormone that must be synthesized to reach an effective blood concentration
The posterior pituitary is really a ?
neural extension of the hypothalamus.
The hormones of the posterior pituitary are not synthesized in the posterior pituitary itself but in the hypothalamus, specifically in the cell bodies of two hypothalamic nuclei (the supraoptic and paraventricular nuclei) whose axons pass down the neural axons to accumulate at the axon terminals in the posterior pituitary.
in the hypothalamus
The hormones of the posterior pituitary are not synthesized in the posterior pituitary itself but in the hypothalamus, specifically in
the cell bodies of two hypothalamic nuclei (the supraoptic and paraventricular nuclei) whose axons pass down the neural axons to accumulate at the axon terminals in the posterior pituitary.
In regards to the hormones of the posterior pituitary, Stimuli (e.g., neurotransmitters) generate...... ; these action potentials propagate __________. The hormone then enters the
-action potentials in the neurons

-
to the axon terminals and trigger the release of the hormone by exocytosis

-capillaries to be carried away by the blood returning to the heart.
In regards to the hormones of the posterior pituitary, the brain can receive stimuli and respond as if
it were an endocrine organ.
By releasing its hormones into the general circulation, the posterior pituitary can modify ....
the function of distant organs (such as the kidney).
The two posterior pituitary hormones are ___.
oxytocin and vasopressin
Oxytocin stimulates ?
contraction of smooth muscle cells in the breasts, which results in milk secretion during lactation, and stimulates contraction of uterine smooth muscle during labor.
Although oxytocin is also presenting males, its functions in males are _____.
uncertain
Vasopressin acts on ?
smooth muscle cells around blood vessels to cause muscle contraction, which constricts blood vessels and increases blood pressure.
Vasopressin also acts within the kidney to ?
decrease water excretion in the urine, thus retaining fluid in the body and helping to maintain blood volume
Because of its kidney function, vasopressin is also known as ?
anti-diuretic hormones (ADH).
Vasopressin and oxytocin are also produced in other areas of the brain and serve in those sites as?
neurotransmitter or neuromodulators.
How are Hypothalamic neurons different from those that produce the hormones released from the posterior pituitary?
secrete hormones that control the secretion of all the anterior pituitary hormones.
Hypothalamic neurons are different from those that produce the hormones released from the posterior pituitary; secrete hormones that control the secretion of all the anterior pituitary hormones. Several hypothalamic nuclei sends terminals to ?
the median eminence.
The hypothalamic hormones that regulate anterior pituitary function are collectively termed?
hypophysiotropic hormones or hypothalamic releasing or inhibiting hormones.
Hypophysiotropic hormones denotes only those hormones .....
from the hypothalamus that influence the anterior pituitary, but they are not categorized as hypophysiotropic hormones.
With one exception, each of the hypophysiotropic hormones is the first in a three-hormone sequence:
(1)A hypophysiotropic hormone controls the secretion of (2) an anterior pituitary hormone, which controls the secretion of (3) a hormone from some other endocrine gland (this last hormone then acts on its target cells)
The adaptive value of three-hormone sequence of hypophysiotropic hormones is that .......
they permit a variety of important hormonal feedbacks. They also allow amplification of a response of a small number of hypothalamic neurons into a large peripheral hormone signal.
The anterior pituitary secretes at least __ hormones, but __ ___have well-established functions.
- eight

- only six
All peptides, these six “classical” are
- follicle-stimulating hormone (FSH),

-luteinizing hormone (LH)
- growth hormone (GH; aka somatotropin),

- thyroid-stimulating hormone (TSH; aka thyrotropin)

- prolactin

-adrenocorticotropic hormone (ACTH; aka corticotrophin).
The following hormones: growth hormone (GH; aka somatotropin), thyroid-stimulating hormone (TSH; aka thyrotropin), prolactin, and adrenocorticotropic hormone (ACTH; aka corticotrophin) are secreted by ...... whereas FSH and LH, collectively termed gonadotropic hormones (aka gonadotropins) because they stimulate .....

The other two peptides in the anterior pituitary, beta-lipotropin and beta-endorphin have unknown physiological effects.
- a distinct cell type in the anterior pituitary

- the gonads, are usually secreted by the same cell.
FSH and LH, collectively termed ?
gonadotropic hormones (aka gonadotropins)
gonadotropic hormones (aka gonadotropins) are called that because they stimulate ?
the gonads
The other two peptides secreted by the anterior pituitary , beta-lipotropin and beta-endorphin have ...... physiological effects.
unknown
The other two peptides secreted by the anterior pituitary that are not part of the classic six are
beta-lipotropin and beta-endorphin
The only major function of two of the six is to stimulate their target cells to secrete other hormones (and to maintenance the growth and function of these cells):
- Thyroid-stimulating hormone induces the thyroid to secrete thyroxine and triiodothyronime
- Adrenocorticotropic hormone – meaning hormone that stimulates the adrenal cortex- stimulates that gland to secrete cortisol
Three other anterior pituitary hormones also stimulate the secretion of another hormone but have an additional function as well.
FSH and LH stimulate the gonads to secrete the sex hormones- estradiol and progesterone from the ovaries, or testosterone from the testes – but in addition, they regulate the growth and development of Ova and Sperm

- Growth hormone stimulates the liver to secrete a growth-promoting peptide hormone known as insulin-like growth factor I (IGF-I) and in addition, exerts direct effects on metabolism
Growth hormone from the anterior pituitary stimulates?
- the liver to secrete a growth-promoting peptide hormone known as insulin-like growth factor I (IGF-I) and in addition, exerts direct effects on metabolism
Prolactin is unique among the anterior pituitary hormones in that
its major function is not to exert control over the secretion of a hormone by another endocrine gland.
Prolactin most important action is to stimulate?

Secondary action of Prolactin?
- development of mammary glands and milk lactation,

- prolactin exerts a secondary action to inhibit gonadotropin secretion, thus decreasing fertility when a woman is breast-feeding.
In the male, prolactin may facilitate several components of
reproductive function, although its precise roles are uncertain
Secretion of the anterior pituitary hormones is largely regulated by ________ produced by and collectively called ?
- hormones

- the hypothalamus

- the hypophysiotropic hormones
Hypophysiotropic hormones are secreted by _________ that originate in ..... and terminate in ?
-neurons

-discrete areas of the hypothalamus

-the median eminence around the capillaries that origins of the hypothalamopituitary portal vessels.
With hypophysiotropic hormones, The generation of action potentials in these neurons causes them to secrete
-their hormones, much as action potentials cause other neurons to release neurotransmitters by exocytosis.
Hypothalamic hormones, enter the ____________ and are carried by the ......... to the ?
-capillaries

-hypothalamo-pituitary portal vessels

-anterior pituitary.
When the hypothalamic hormones act upon the various anterior pituitary cells to control ?
-their hormone secretions.
hypothalamic neurons secrete hormones in a manner identical to ?
that described previously for the hypothalamic neurons whose axons end in the posterior pituitary.
the hormones that are made in hypothalamic neurons, travel ...., and are released...?
-down axons to the neuron terminals

-in response to action potentials in the neurons.
Two critical differences, distinguish the two pituitary hormone systems:
- 1) The axons of the hypothalamic neurons that secrete the posterior pituitary hormones leave the the hypothalamus and end in the posterior pituitary, whereas those that secrete the hypophysiotropic hormones remain in the hypothalamus, ending in the median eminence.

- (2) Most of the posterior pituitary capillaries into which the posterior hormones are secreted immediately drain into the main blood stream, which carries the hormones to the heart for distribution to the entire body.
The hypophysiotropic hormones enter capillaries ...... , but empty into ......., which carry them to the?
- in the median eminence of the hypothalamus that do not directly join the main bloodstream

- the hypothalamo-pituitary portal vessels

-anterior pituitary.
If a cell has an appropriate receptor for a given hypophysiotropic hormone, that cell will respond by
increasing or decreasing the secretion of its pituitary hormone.
If a pituitary hormone is secreted, it will diffuse into ?
the same capillaries that delivered the hypophysiotropic hormone. .
If a pituitary hormone is secreted, it will diffuse into the same capillaries that delivered the hypophysiotropic hormone. These capillaries then drain into ..... , where the pituitary hormones .....?
- veins, which enter the systemic circulation

- can come into contact with their target cells.
The anterior pituitary is exposed to ....... of the hypophysiotropic hormones than those existing in the general bloodstream
- much higher plasma concentrations
There are multiple discrete hypophysiotropic hormones, each secreted by ....... and influencing the release of ?
- a particular group of hypothalamic neurons

-one or, in at least one case, two of the anterior pituitary hormones.
Each hypophysiotropic hormone is named for ?
-the anterior pituitary hormone whose secretion is controls.

-

-
secretion of ACTH (corticotrophin) is stimulated by ?
-corticotrophin-releasing hormone (CRH)
secretion of growth hormone is stimulated by
-growth hormone-releasing hormone (GHRH)
secretion of thyroid-stimulating hormone (thyrotropin) is stimulated by
-thyrotropin-releasing hormone (TRH)
secretion of both luteinizing hormone and follicle-stimulating hormone (the gonadotropins) is stimulated by?
gonado-tropin-releasing hormone (GnRH)
Two of the hypophysiotropic hormones do not stimulate the release of an anterior pituitary hormone but rather inhibit its release.
- Somatostatin (SS)

- Dopamine (DA)
Somatostatin (SS) inhibits ?
the secretion of growth hormone.
Dopamine (DA), tonically inhibits?
the secretion of prolactin.
Growth hormone is controlled by two hypophysiotropic hormones?
Somatostatin (SS) inhibits the release and growth hormone releasing hormone, which stimulates it.
The rate of growth hormone secretion depends, therefore, upon the .....as well as.....?
- releative amounts of the opposing hormones released by the hypothalamic neurons,

- upon the relative sensitivities of the anterior pituitary to them.
All of the known hypophysiotropic hormones also occur in locations other than the hypothalamus, particularly ...?
in the other areas of the central nervous system, where they function as neurotransmitters or neuromodulators, and in the GI tract.
The one hypophysiotropic hormone that is not a peptide is ?
- dopamine

- which is a amine and a member of the catecholamine family.
What controls secretion of the hypophysiotropic hormones?
Some of the neurons that secrete hypophysiotropic hormones may possess spontaneous activity but firing of most of them requires neural and hormonal input.
Neurons of the hypothalamus receive stimulatory and inhibitory synaptic input from ..... and specific neural pathways influence ..?
- virtually all areas of the central nervous system

- the secretion of the individual hypophysiotropic hormones.
A large number of neurotransmitters (ex. The catecholamines and serotonin) are released ; not surprisingly, therefore, drugs that influence these neurotransmitters can alter...?
- at the synapse on the hormone-secreting hypothalamic neurons

-the secretion of the hypophysiotropic hormones.
Corticotropin-releasing hormone (CRH) from the hypothalamus stimulates ...... to secrete .... which in turn stimulates the adrenal cortex to secrete ...
-

- the anterior pituitary

- ACTH

- cortisol.
A wide variety of sensory stimuli resulting from physical or emotional stress act _______ to the hypothalamus to increase CRH secretion, and therefore, ....?
-via neural pathways

- ACTH and cortisol secretion.

-
Even in the absence of stressful stimuli, cortisol secretion varies in a regular manner during a 24 hour period because ...
neural rhythms within the central nervous system also impinge upon the hypothalamic neurons that secrete CRH.
A prominent feature of each of the hormonal sequences initiated by the hypophysiotropic hormone is?
negative feedback exerted upon the hypothalamo-pituitary system by one or more of the hormones in its sequence
The hormonal sequencing is effective in ..?
dampening hormonal responses- that is, in limiting the extremes of hormone secretory rates.
The situation described for cortisol, in which the hormone secreted by the third endocrine gland in a sequence exerts a negative feedback effect over the anterior pituitary and/or hypothalamus, is known as
a long-loop negative feedback.
This type of feedback (long-loop negative feedback) exists for...?
each of the three-hormone sequences initiated by a hypophysiotropic hormone.
Long-loop feedback does not exist for ______ since ........ meaning, it does not participate in a three-hormone sequence.
-prolactin

-this is one anterior pituitary hormone that does not have major control over another endocrine gland
there is negative feedback in the prolactin system, for this hormone itself acts .....?
upon the hypothalamus to stimulate the secretion of dopamine, which then inhibits the secretion of prolactin.
The influence of an anterior pituitary hormone on the hypothalamus is known as
a short loop negative feedback.
Like ......, several other anterior pituitary hormones, including , ________ also exert such feedback on the hypothalamus.
- prolactin

- growth hormone
Keep in mind that there are many stimulatory and inhibitory hormonal influences on the ..............other than those that fit the feedback patterns.
hypothalamus and/or anterior pituitary
a hormone that is not itself in a particular hormonal sequence may ?
nevertheless exert important influences on the secretion of the hypophysiotropic or anterior pituitary hormones in that sequence.
estrogen markedly enhances the secretion of prolactin by the anterior pituitary, even though .
estrogen secretion is not normally controlled by prolactin
the sequences we have been describing should not be viewed as
isolated units.