Pituitary and Hypthalamic Hormones Flashcards
1
Q
What is a hormone?
A
A substance secreted by a gland or tissue into the blood that binds to receptors in other tissues where they affect specific physiological processes.
2
Q
Chemically hormones fall into 3 main categories. They are:
A
peptides, steroids, or amines (and their derivatives)
3
Q
Insulin and growth hormone are examples of what type of hormone? (peptide, steroid, or amine)
A
peptide hormones
4
Q
Estrogen, testosterone, and cortisol are examples of what type of hormone? (peptides, steroids, or amines)
A
steroids
5
Q
Epinephrine and thyroxine are examples of what type of hormone? (peptide, amine or steroid)
A
amines
6
Q
What is a neurohormone?
A
A subclass of hormones secreted by neurons.
7
Q
Name 2 neurohormones.
A
Vasopressin and oxytocin
8
Q
Describe the steps of peptide synthesis.
A
- genes encoding peptides transcribed to mRNAs 2. mRNAs translated on ribosomes to make preprohormone (which has a signal peptide) 3. Signal peptide directs transport to the endoplasmic reticulum where signal peptide is cleaved leaving a prohormone. 4. Prohormone transported to Golgi apparatus, where it is sequestered into secretory vesicles. 5. Within the vesicles, prohormone is further cleaved into the final active form of the hormone. 6. Secretion occurs when the contents of these vesicles are released.
9
Q
What is preprohormone?
A
A peptide hormone precursor that includes a signal peptide.
10
Q
What is prohormone?
A
A peptide hormone precursor that was a preprohormone but now has the signal peptide cleaved off. Prohormone is transported to the Golgi apparatus and is sequestered there into secretory vesicles.
11
Q
What are steroid hormones synthesized from?
A
From cholesterol.
12
Q
Where does the body get the cholesterol it needs to make steroid hormones?
A
It gets it from dietary cholesterol or synthesizes it de novo from acetyl coA
13
Q
What are the major steroid hormones?
A
cortisol aldosterone testosterone (and other androgens) estradiol (and other estrogens) progesterone.
14
Q
Where are cortisol and aldosterone synthesized?
A
adrenal cortex
15
Q
Where is testosterone produced?
A
by the testes
16
Q
Where are estradiol and progesterone synthesized?
A
in the ovaries
17
Q
What is the basic action of hormones?
A
They are secreted into the blood by endocrine glands or tissues. When they reach their target tissues they bind to membrane or nuclear receptors, initiating a chain of events that ultimately results in the phsyiologic effects of the hormone.
18
Q
Which hormones readily enter the target cell?
A
steroid hormones (testosterone, estradiol, porgesterone), thyroid hormone and vitamin D. They are all lipophilic and readily cross the lipid bilayer. Once inside the cell they bind to their nuclear receptors and intitiate gene transcription.
19
Q
How to peptide hormones and catecholamines get into the cell?
A
They do not. They bind to membrane receptors like heteromeric G proteins, initiating a cascade of events involving generation of or inhibition of production of second messengers such as cAMP, cGMP, and IP3. These second messengers are what activate or induce transcription factors and cellular function.
20
Q
What is an autocrine hormone?
A
A hormone that is secreted by a gland, circulates through the blood and then acts upon autocrine receptors on that same cell.
21
Q
What is a paracrine hormone?
A
a hormone that is released from a gland and acts locally on cells near the one that released it.
22
Q
Define neuroendocrine.
A
Neuroendocrine is the joining of both the neuro and and endocrine system. A neurotransmitter in the brain that acts on the pituitary gland in the brain is a neurohormone. The neurotransmitter response is fast. Once a hormone leaves the pituitary it is an endocrine hormone which acts much slower for a sustained effect.
23
Q
What two structures in the brain regulate the function of much of the endocrine system?
A
The hypothalamus and the pituitary
24
Q
The hypothalamus is located in the ______ _______ and is connected by the _________ to the pituitary gland.
A
ventral diencephalon; pituitary stalk (infundibulum)
25
The pituitary sits in a bony cavity in the sphenoid bone called the \_\_\_\_\_\_\_\_\_\_\_\_\_.
sella tursica
26
How many lobes does the pituitary have?
2. The anterior pituitary and the posterior pituitary
27
one lobe of the pituitary is continous with the hypothalamus, and contains axons originating from the hypothalmic nuclei. Which lobe?
Posterior
28
The posterior pituitary stores and secretes which 2 hormones?
ADH (vasopressin) and oxytocin
29
Where are oxytocin and vasopressin (ADH) synthesized?
In the supraoptic nucleus and paraventricular nucleus of the hypothalamus.
30
How are vasopressin (ADH) and oxytocin carried to the posterior pituitary?
By axonal transport
31
Which lobe of the pituitary is NOT directly connected to the hypothalamus?
The anterior pituitary
32
How is the anterior pituitary connected with the hypothalamus?
The anterior pituitary is conneced to the hypothalamus by the vessels of the hypophyseal portal circulation.
33
If not directly connected to the hyothalamus, aside from by blood supply, how does the hypothalamus work to get the anterior pituitary to release hormones?
They hypothalamus synthesizes and releases both hypothalmic releasing and inhibitory hormones that are carried through the hypophyseal portal veins to the anterior pituitary and regulate the release of trophic hormones.
34
What did Dr. Lumpkin mean when he said hormonal activity in the body had a 'cascading' effect?
Starting with the neurtransmitter that acts on the pituitary gland, the action is quick and a little bit of neurotransmitter is released to act on the pituitary. As the pituitary responds it releases a larger amount of hormone, and the action lasts longer. As the hormone released acts on the glands of the body, even more hormone is released and lasts even longer than the previous two steps. More hormone, lasting longer and long.
35
peptide hormones are polar or nonpolar?
polar. they cannot readily cross the lipid bilayer of the cell membrane.
36
What type of hormone is thyroxine? (peptide, steroid or amine)?
amine
37
What is unique about thyroid hormone?
It is structurally derived from the amines but it is more lipid soluble than water soluble so it crosses the cell membranes and bind to thryoid receptors in the chromatin
38
Name 4 hormones that the ovaries release into the body.
estrogens, progestins, inhibin, relaxin
39
Name 3 hormones released by the pancreatic islets.
insulin,glucagon, and somatostatin
40
Name 5 of the most common hormones released form the digestive tract.
gastrin, secretin, CCK, GIP, motilin
41
Name a hormone released by the thymus.
thymopoietin Remember, the thymus disappears in adulthood
42
Name 3 hormones released by the thyroid gland.
T4 (thyroxine), T3 (triiodothyronine), and calcitonin
43
Name the hormone released from the pineal gland.
Melatonin
44
Name 2 hormones released by the testes?
androgens (especially testosterone), and inhibin
45
What hormone is released from fat?
Leptin
46
Name 3 hormones released from the kidney.
erythropoietin (EPO), calcitriol, and renin
47
The adrenal gland is divided into 2 regions, they are:
the adrenal medulla and the adrenal cortex
48
Name 2 hormones released by the adrenal medulla.
norepinephrine and epinephrine
49
Name 3 hormones released from the adrenal cortex.
cortisol, aldosterone, and androgens
50
Name a hormone released from the heart.
atrial natriuretic peptide
51
Name the hormone released from the parathyroid glands.
parathyroid hormone PTH
52
Name 7 hormones released from the anterior pituitary gland.
ACTH, TSH, GH, PRL, FSH, LH, and MSH
53
Name 2 hormones released from the posterior pituitary.
ADH and oxytocin
54
Which hormones come from the hypothalamus.
production of ADH, oxytocin. Releasing hormones: TRH, CRH, GHRH, GnRH. And somatostatin
55
What is a releasing hormone?
A hormone released by the hypothalamus that acts on the anterior pituitary gland.
56
What is an inhibiting hormone?
A hormone released by the hypothalamus that inhibits the release of hormone from the anterior pituitary.
57
What is the adenohypophysis?
anterior pituitary
58
What is the neurohypophysis?
posterior pituitary
59
60
What is the advantage of having a rich portal blood supply to the anterior pituitary?
not only does the blood carry the releasing hormone to the anterior pituitary but then the blood is right there to receive the hormone released by the pituitary in response and circulate it.
61
What does TSH do?
stimulates thyroid hormone synthesis and release by the thyroid gland
62
What does ACTH (adrenocorticotropic hormone) do?
It stimulates synthesis of adrenocortical steroids
63
What do the gonadotropins (LH and FSH) do?
promote steroidogenesis and gametogenesis by the testes and ovaries
64
What does prolactin do?
stimulates milk production by the breast
65
What does GH (growth hormone) do?
promotes the synthesis of insulin like growth factors (IGFs) by the liver and other target tissues. The IGFs from the liver ar released into the circulation, whereas IGFs from other tissues act locally in an autocrine manner.
66
What is meant by trophic hormone?
trophic hormones have other endocrine glands as their targets. Trophic hormones do 2 things, they release hormone and they support the structure of the gland.
67
Are feedback systems in the endocrine system continous or cyclical?
They have cyclic variation.
68
What is negative feedback?
the system that controls level of hormones by how much hormone is in the blood. Increased blood levels of hormone inhibit a hormone's synthesis.
69
What are the 3 types of feedback loops?
long-loop feedback, short loop feedback, and ultra short loop feedback.
70
What is the thin band at the anterior hypothalamus?
lamina terminalis
71
The tissue in the middle of the pituitary is called the?
median eminence
72
At the back end of the hypothalamus is a cluster of nuclei called the?
mammalary body
73
What does the medial preoptic nucleus of the hypthalamus do?
It makes Gonadropin releasing hormone (GnRH)
74
What does the anterior hypothalmic area do?
Regulates metabolism
75
What does the paraventricular nucleus do?
Along with the supraoptic nucleus, it makes vasopressin and oxytocin.
76
What does the ventral medial nucleus of the hypothalamus do?
regulates growth hormone
77
What does the periventricular nucleus do?
It is the square shaped sheet that covers a part of the hypothalamus. It surrounds the 3rd ventricle. It also makes growth hormone and releases somatostatin.
78
What does the arcurate nucleus do?
It helps regulate growth and growth hormone
79
What does the mammalary body do?
It is the passageway for how information enters and leaves the hypothalamus
80
The cluster of axons travelling down the pituitary stalk store which two hormones?
vasopressin and oxytocin
81
What is the most common pathology of the pituitary gland?
tumors. Because of the bony plate, tumors displace pituitary tissue upwards against the optic nerve and can cause vision disturbances.
82
What are the 2 types of anterior pituitary tumors?
macroadenomas and microadenomas
83
What are the 2 things macroadenomas do?
They oversecrete the hormone of the cells of their origin and the excess tissue becomes locally destructive to the healthy tissue surrounding it. (This can cause other problems with other hormones, etc)
84
What is the most common anterior pituitary tumor and what symptoms does it cause?
Prolactinoma. it causes infertility, abnormal mik production, breast growth.
85
What is the difference between macroadenoma and microadenoma?
microadenomas do oversecrete the hormone of their cell of origin but they do not do local destruction to the surrounding tissue.
86
What do tumors of the anterior pituitary gland do to the posterior pituitary gland?
Nothing. the posterior is separate and continues making vasopressin and oxytocin
87
Where does the pituitary get it's blood supply from?
The superior hypophyseal artery (a branch off of the carotid)
88
Where does the superior hyophyseal artery go (on the pituitary gland)?
to the pituitary junction at the median eminence
89
Both blood vessles and _____ fibers are in the median eminence.
nerve
90
What happens to the pituitary blood supply once the superior hypophyseal artery reaches the median eminence?
It forms capillary loops around the median eminence. This is called the **primary capillary plexus**. The capillaries are in direct contact with the nerve terminals of the releasing neuron cells.
91
From the primary capillary plexus, where does the blood supply of the pituitary go?
forms the portal vein that travels down the pituitary stalk.
92
The long portal vein that carries the blood supply from the hypothalamus to the anterior pituitary also carries with it?
The neurohormones that will act on the anterior pituitary gland.
93
What happens to the blood supply as it leaves the long portal vein at the anterior pituitary?
It splits to form the secondary capillary plexus which breakes into even smaller sinusoids, which bath the anterior pituitary with blood, allowing neurohormones to act on it and to accept the hormones released by the anterior pituitary to be distributed to the body.
94
Ultimately, the blood supply to the anterior pituitary is __________ and the blood supply to the posterior pituitary is \_\_\_\_\_\_\_\_\_\_\_\_\_.
venous; arterial
95
The blood supply to the posterior pituitary is purely arterial and comes from the \_\_\_\_\_\_\_\_\_\_\_\_\_.
Inferior hypophyseal artery.
96
If the anterior lobe of the pituitary receives venous blood and the posterior lobe receives arterial blood, what would happen in a cardiovascular crisis, like a hemorrhage?
The posterior pituitary, being supplied by arterial blood, has the ability to autoregulate and preserve circulation to it better than the anterior posterior which only has low pressure venous blood supply, it can be severely compromised by a massive blood loss.
97
The blood-brain barrier (the tight junction of epithelial cells that line the capillary) do not exist at which 2 structures in the pituitary?
at the median eminence and the arcuate nucleus.
98
One of the circumventricular organs of the brain does not have a blood brain barrier. What is it's name?
The Organum vasculosum of lamina terminals (OVLT of the supraoptic crest)
99
Name 8 things that will stimulate ADH secretion.
1. ECF osmololity increase 2.Volume decrease 3.Pressure decrease 4. CSF sodium increase 5. Pain 6. Stress 7. Temperature increase, 8. Beta-adrenergic agonists 9.certain drugs.
100
Name 5 types of drugs that might increase ADH secretion.
Nicotine, opiates, barbiturates, sulfonylureas, antineoplastic agents.
101
Name 5 things that will inhibit ADH secretion.
Temperature decrease, alpha-adrenergic agonists, ethanol, cortisol, thyroid hormone
102
Vasopressin can also stimulate ACTH which stimulates the _______ gland to make \_\_\_\_\_\_\_\_.
adrenal gland; cortisol
103
What is the difference between vasopressin and oxytocin and why is that important?
Both have 9 amino acids are nearly identical in structure. They only differ in 2 amino acids. The 2 different amino acids are what makes them specific for each of their receptors. However, in situations of high pathological levels of one of these hormones, they might start to cross over and react with the other's receptor.
104
What is GHRH, where does it come from and what does it do?
Growth hormone releasing hormone. It comes from the hypothalamus and acts on the anterior pituitary to cause it to release growth hormone.
105
What hormone from the hypothalamus inhibits the release of growth hormone from the anterior pituitary?
Somatostatin (SS)
106
Where is somatostatin produced?
The periventricular nucleus
107
Which hypothalamic hormone is a ubiquitous inhibitor?
somatostatin
108
What is TRH? Where does it come from and what does it do?
TRH is Thyrotropin-releasing hormone. It comes from the hypothalamus and stimulates the release of TSH from the anterior pituitary. TRH can also stimulate the release of prolactin (PRL) from the anterior pituitary.
109
What is DA? Where does it come from and what does it do?
DA (dopamine) is a prolactin inhibiting factor (PIF). It comes from the hypothalamus and acts on the anterior pituitary to inhibit the release of prolactin (PRL).
110
What hormone inhibits the release of TSH from the anterior pituitary?
Somatostatin (SS)
111
What is GnRh? Where does it come from and what does it do?
Gonadotropin-releasing hormone. it somes from the hypothalamus and causes the release of LH (leutinizing hormone) and FSH (follicle stimulating hormone) from the anterior pituitary gland.
112
What is CRH? Where does it come from and what does it do?
Corticotropin-releasing hormone. It comes from the hypothalamus and causes the release of ACTH (adrenocorticotropic hormone) from the anterior pituitary gland.
113
The hypothalamus is the site of ___________ of neurohormones and the _____________ \_\_\_\_\_\_\_\_\_\_\_ is the site of storage and release.
synthesis; meidan eminence
114
Preprohormone synthesis occurs in the _____________ and is directed by specific \_\_\_\_\_.
endoplasmic reticulum; mRNA
115
\_\_\_\_\_\_\_ are cleaved from the preprohormone, producing a prohormone which is transported to the \_\_\_\_\_\_\_\_\_\_.
Signal peptides; golgi apparatus
116
Additional peptide sequences are cleaved in the Golgi apparatus to form the __________ which is packaged in secretory glands for later use.
hormones
117
Steriod hormones are derivatives of \_\_\_\_\_\_\_\_\_\_\_
cholesterol
118
