Endocrine: Intro & Hypothalamus/Pituitary Unit Flashcards
1
Q
Hormones are the product of what tissue?
A
an endocrine gland
2
Q
How are hormones transported to their peripheral/distant target cells?
A
the blood stream
3
Q
Hormones may exert a trophic effect, meaning it regulates what two things?
A
other gland hormone secretion
growth/integrity of an endocrine gland
4
Q
Hormones which act on distant targets are ____crine
A
endocrine
5
Q
Hormones which regulate processes in neighboring cells…
A
paracrine
6
Q
Hormones that act upon themselves…
A
autocrine
7
Q
hormones which regulates its own intracellular activity without being secreted…
A
intracrine
8
Q
A hormone which originates int he neuron.
after axonal transport, carried via blood or synaptic transmission
A
neurocrine
9
Q
What tissue in the heart can have an endocrine gland effect?
A
epicardial fat
10
Q
What are the three broad ways hormones are classified?
A
chemical structure
plasma solubility
signal transduction pathway
11
Q
What are the three types of hormones, as based on their chemical structure?
A
Peptides
Amines
Steroids
12
Q
Steroid hormones are derived from ________
A
cholesterol
13
Q
Amine hormones are derived from _______, and are synthesized where?
A
tyrosine derived
adrenal medullae and thyroid
14
Q
What two hormone classes are amine hormones?
A
catecholamines
thyroid hormones
15
Q
Peptide hormones are derived from…
A
amino acids
16
Q
Most hormones are what type of chemical structure?
A
peptide
17
Q
______ hormones are transported in the blood stream as dissolved.
A
Hydrophilic
18
Q
__________ hormones are transported via binding proteins in the blood
A
Hydrophobic
19
Q
Which hormone types are hydrophilic?
A
peptide hormones and catecholamines
20
Q
What two hormone types are hydrophobic?
A
thyroid and steroid based
21
Q
Hydrophobic proteins have ___% bound and < ____ % free
A
99% bound
1% free
22
Q
These substances…
- provide reserve of hormone
- keep hormone inactive in blood
- involved in hormone turnover
A
Binding proteins
23
Q
What 5 factors determine plasma hormone concentration?
A
availability of binding proteins
secretion from gland
inactivation and excretion
peripheral conversion
internalization of hormone/receptor complex
24
Q
Inactivation and excretion of hormones occurs in what two organs?
A
kidney and liver
25
Hormones are inactivated in the liver via...
glucuronidation and sulfate conjugation
26
What effect does glucuronidation and sulfate conjucation have on hormone excretion by the kidneys?
increases water solubility
27
What structural class are the following hormones?
```
FSH
TSH
LH
hCG
Carb hormones
```
Glycoproteins
28
What structural class are the following hormones?
```
ACTH
AT
Calcitonin
PTH
MSH
Growth Factors
Oxytocin
ADH
GH
Somatostatin
Insulin
Glucagon
```
Peptide Hormones
29
What structural class are the following hormones?
```
Aldosterone
Cortisol
Estradiol
Progesterone
Estrogen
Testosterone
DHEA
Vitamin D
```
Steroids
30
What structural class are the following hormones?
```
epinephrine
NE
DA
T4
T3
```
Amine
31
Which signal transduction group of hormones?
enter nucleus where hormone binds to receptor on DNA
Group I
32
Which signal transduction group of hormones?
Membrane enzyme: Adenylyl Cyclase
Second messenger: cAMP
Kinase: cAMP PK
IIA
33
Which signal transduction group of hormones?
Membrane enzyme: Guanylyl Cyclase
Second messenger: cGMP
Kinase: cGMP PK
IIB
34
Which signal transduction group of hormones?
Membrane enzyme: PLC
Second messenger: DAG, IP3
Kinase: PKC, Calmodulin-dep PK
IIC
35
Which signal transduction group of hormones?
Membrane enzyme: NA
Second messenger: NA
Kinase: Serine or threonine Kinase
IID
36
The physiological effect of Group I hormones occurs after what?
binding to nuclear receptors
37
What hormone type?
Precursor: specific gene
Site of Synth: ribosomes, ER, golgi
Storage: granules
peptides
38
What hormone type?
Precursor: tyroside or iodide
Site of Synth: enzymatic in cytosol or in follicular cell/colloid
Storage: granules or follicular cells
amines
39
What hormone type?
Precursor: cholesterol
Site of Synth: cytosol, ER, mito
Storage: not stored
Steroids
40
The peptide chain that is formed after mRNA translation for peptide hormone synthesis is called...
preprohormone
41
What happens to the preprohormone in the ER?
cleaved to prohormone, sent to golgi
42
What stimulates the secretion of peptide hormones?
increase in cytosolic cAMP and Ca
43
What two hormone types may undergo peripheral conversion after release?
steroids and amine
44
what effect does peripheral conversion confer on a hormone?
increased activity several-fold
45
Vitamin D3 is converted to 1,25-dihydroxyvitamin D via...
hydroxylation in liver and kindey
46
testosterone is converted to DHT via...
androgens formed in androgen dependent tissues
47
Testosterone is converted to estradiol via...
brain and testes
48
T4 is converted to T3 via
most tissues
49
This method of hormone secretion:
activated by blood borne substrate
A-Humoral
50
An example of A-humoral secretion is...
PTH regulation of calcium
51
Describe the mechanism of PTH regulation of calcium...
low calcium triggers PTH release
PTH stimulates release from bones, increases uptake in kidneys and intestines
52
This method of hormone secretion:
-extension of CNS that signals gland to secrete hormone
B-Neural
53
What are three stimuli for B neural hormone secretion?
psychic/emotional stress
fight response
altered physiologic states
54
SNS stimulation of adrenal medulla leading to NE/epi release is an example of...
B neural secretion
55
This method of hormone secretion:
hormones A regulates secretion of hormone B, which stimulates secretion of hormone C
C-hormonal
56
TRH from the hypothalamus stimulates pituitary release of TSH, which stimulates thyroid secretion of T4/T3. This is an example of...
C hormonal secretions
57
What type of hormone feedback?
- most common
- hormone action inhibits further secretion
- regulated by long loops and short loops
- essential for maintaining homeostasis
Negative feedback
58
Testosterone's inhibitory action on the anterior pituitary and the hypothalamus are examples of ____ loops in negative feedback
long loops
59
the anterior pituitary's inhibition of the hypothalamus in testosterone secretion is an example of the ____ loop in negative feedback
short
60
Which method of feedback?
- least common
- hormone stimulates increased secretion
- ex: estrogen, oxytocin
positive feedback
61
In positive feedback, estradiol stimulates ______ to secrete more hormone
anterior pituitary
62
Hormone action is dependent on...
plasma or nuclear receptors
63
Hydrophilic hormones like peptides and catecholamines bind where on their target cell?
receptor channel on cell membrane
64
hydrophobic hormones like steroids and thyroid hormones diffuse through the bilayer and bind where?
nuclear receptor
65
This is the responsiveness of a target tissue to a hormone.
It is expressed in the dose-response relationship
responsiveness
66
____ is the minimal hormone concentration to achieve a response.
threshold
67
_____ is the concentration of hormone that produces 50% of maximum response
sensitivity
68
_____ is the effect of a saturating dose of a hormone
maximal response
69
A decrease in target cells , signal transduction mechanisms, or enzyme activity in the cell would cause...
decreased maximal response
70
a decrease in hormone-receptor affinity and a decrease in receptor number would cause... (down shift)
decreased sensitivity (right shift)
71
This occurs when hormones have a greater overall effect when combined.
synergism
72
This occurs when one hormone cannot exert its full effect without another hormone's presence.
permissiveness
73
This occurs when one hormone reduces the effect of another hormone
antagonism
74
This happens when a hormone regulates the number or affinity of its own receptor
autologous up/down regulation
75
This occurs when a hormone regulates the number and affinity of another hormone's receptor...
heterologous up/down regulation
76
Tumors, hyperplasia and autoimmune stimulation typically cause...
overproduction
77
autoimmune destruction, tumor, ischemia, infx, hemorrhage or dietary issues often cause...
under production
78
Anterior or posterior pituitary?
```
metabolism
growth
reproduction
lactation
stress response
```
anterior
79
Anterior or posterior pituitary?
```
water balance
parturition and lactation
BP regulation
Cardiac function
diuresis
```
posterior pituitary
80
The ________ receives impulses from other parts of the brain, and diverts them to the _________
Hypothalamus
pituitary
81
The function of the hypothalamus-pituitary unit is to coordinate ___________ to maintain __________
physiologic response of organs
maintain homeostasis
82
These neurons originate in the hypothalamus, sending their axons down the infundibular process to terminate in the posterior pituitary...
magnocellular neurons
83
Where do magnocellular neurons release their hormones?
capillary bed
84
Where do parvicellular neurons originate and terminate?
originate: hypothalamus
terminate: median eminence
85
Parvicellular neurons link the hypothalamus with the...
anterior pituitary
86
Parvicellular neurons secrete ______ hormones
releasing hormones
87
Releasing hormones from parvicellular neurons are transported to the anterior pituitary by...
hypothalamo-hypophyseal portal vessels
88
This type of hormone regulates the secretion of tropic hormones from the anterior pituitary
releasing hormones
89
what type of neurons are located primarily in the paraventricular nuclei and the supraoptic nuclei?
magnocellular neurons
90
GHRH acts on what cell types to increases synthesis of GH?
Somatotrophs
91
Somatotrophs (GH releasing cells) account for ___% of pituitary cell population
45%
92
TRH acts on what cell types to increase synthesis of TSH?
thyrotrophs
93
Thyrotrophs (TSH releasing cells) account for ___% of pituitary cell population
3-5%
94
Somatostatin decreases synthesis of what two hormones?
GH and TSH
95
TRH acts on what cell types to increase synthesis of prolactin?
mammotrophs
96
Mammotrophs account for what percent of pituitary cell population?
10-15%
97
GnRH increases synthesis of what two hormones?
LH and FSH
98
GnRH stimulates what cell types to increase synthesis of FSH?
Gonadotrophs
99
Gonadotrophs make up ___% of pituitary cell population
15%
100
This hormone:
- acts on many tissues
- stimulates growth via IGF production in liver
- Works on energy metabolism
GH
101
This hormone:
- acts on thyroid gland
- Stimulates growth of thyroid gland
- Stimulates secretion of T3, T4
TSH
102
This hormone:
- acts on the mammary glands
- stimulates breast development
- stimulates milk production
prolactin
103
This hormone:
- acts on the gonads
- stimulates ovulation and estrogen synth in females
- stimulates testosterone secretion from leydig cells in males
LH
104
This hormone:
- acts on the gonads
- development of follicle in females
- initiates spermatogenesis in males
FSH
105
CRH stimulates what cell type to release ACTH?
corticotrophs
106
Corticotrophs account for ___% of pituitary cell population
15%
107
PRH stimulates what cell type to synthesize prolactin?
lactotrophs
108
Dopamine inhibits the synthesis of what hormone?
prolactin
109
This hormone:
- targets adrenal glands
- stimulates adrenal gland growth
- stimulates synthesis of corticosteroids
ACTH
110
This hormone:
- acts on mammary glands
- stimulates breast development and milk production
prolactin
111
these two hormones are synthesized in hypothalamic neuronal cell bodies of magnocellular neurons
ADH and oxytocin
112
ADH and oxytocin are synthesized in the ____ fashion as _____
peptide fashion
preprohormones
113
Describe the half-life of ADH and oxytocin
8 minutes
114
The cys residues of ADH and oxytocin are capable of forming...
disulfide bridges
115
What classification of hormones have the following features?
- transported in axons
- secreted at nerve terminals
- released to fenestrated pituitary capillaries via action potentials
neuropeptides
116
ADH and oxytocin are co-secreted with...
neurophysins
117
These carrier proteins prevent diffusion of hormones out of posterior pituitary axons...
neurophysins
118
NPI is tied to...
oxytocin
119
NPII is tied to...
ADH
120
During intraaxonal transport, the precursor hormone is cleaved to what three substances...
ADH/oxytocin
NP
terminal glycoprotein
121
NP arranges into tetramers that can bind how many ADH?
5 ADH
122
_____ are found in the anterior hypothalamus outside the BBB, and have direct contact with systemic circulation
osmoreceptors
123
what 2 things signal osmoreceptors to stimulate AVP(ADH) release?
loss of intracellular water
increased plasma sodium/chloride
124
osmoreceptors stimulate what type of neurons directly to release AVP?
magnocellular neurons
125
does AVP release occur before or after the stimulation of thirst?
before
126
a __% change in osmolarity above threshold will produce an increase in AVP release, meaning the system is very sensitive
1% change
127
AVP targets what receptor on the kindeys?
V2 receptor
128
AVP secretion results in what three things
1. increased plasma volume
2. decreased osmolarity
3. low urine output
129
What 4 homeostatic adjustments are made with increased plasma osmolarity
AVP secretion, water reabsorption, decreased urine output and stimulation of thirst
130
AVP is released due to increases in blood osmolarity. What else can trigger AVP release?
decrease in blood volume/pressure
131
Baroreceptors decrease their rate of firing when BP decreases. This has what two effects?
increased AVP
thirst center stimulation
132
decreased blood pressure is perceived by the macula densa, resulting in RAAS activation. ATII has what effect on osmoreceptors?
sensitization leading to enhanced AVP release
133
What receptor does AVP act upon to induce vasoconstriction?
V1
134
is the BP mediated AVP system more or less sensitive than the osmolarity system?
less
135
During childbirth (parturition), what two factors stimulate the release of OT?
cervical distension
uterus contraction
136
In the lactating breast, OT stimulates what?
milk ejection
137
In the pregnant uterus, OT induces what action?
smooth muscle contractions
138
signals reaching the PVN and SON provide a ______ feedback of OT
positive
139
Suckling of the nipple in the lactating breast stimulates secretion of ___
OT
140
receptors in the nipple generate what type of impulses that reach the hypothalamus?
afferent
141
OT stimulates milk ejection by causing the contraction of what cells lining milk ducts?
myoepithelial cells
142
continued suckling has what effect via what feedback mechanism?
OT synthesis via positive feedback
143
is sucking required for milk secretion?
no
144
What three stimuli other than suckling can stimulate milk secretion?
sight, smell, sound of infant
145
OT has what effect on the uterus during suckling?
promote uterine regression
146
Receptors in the cervix generate what type of impulse that reach the hypothalamus?
afferent
147
cholinergic synapses within the PVN and SON stimulate the production of what two substances in the posterior pituitary?
OT and NP-I
148
The uterus is more sensitive to OT due to...
increased OTR density
149
By what magnitude is OTR amplified in the pregnant uterus?
200x
150
Increased OTR density is mediated by what three factors?
OT, progesterone, gap junction formation
151
oxytocin has what other two effects outside of milk ejection and uterine contraction?
cardiovascular and cardiometabolic effects
152
What axis for OT resides in the heart?
OT-natriuretic peptide-nitric oxide axis
153
OT causes _____ release from cardiomyocytes.
ANP and BNP
154
ANP stimulates the release of _____ from vascular endothelium
nitric oxide
155
OT is ___x more abundant in the atria than the ventricles
3-4x
156
ANP is found in both atria and ventricles, but mostly in atria. BNP, however, is found mainly in...
ventricles
157
In plasma, OT binds to OTRs present in what three tissue types?
vasculature
kindey
cardiac
158
In the peripheral arterioles, OT induces _______ which decreases pressure and resistance.
NO dependent vasodilation
159
The NO dependent vasodilation mediated by OT, is enhanced by the presence of _____
estrogen
160
In cardiac muscle, OT binds to OTR resuling in synthesis and release of what two substances...
ANP and NO
161
OT mediated release of ANP and NO have what effects on heart?
negative inotropic and chronotropic
162
ANP induces ____ of peripheral arterioles after binding the NPR-A receptor
vasodilation
163
At physiologic conditions, OT stimulates what two processes via renal OTR
diuresis and natriuresis
164
increased plasma OT and reduction in hypothalamic CRF leads to decreased production of what hormone?
cortisol
165
increased ANP in the plasma has what 5 effects?
arteriolar dilation
diuresis, natriuresis, kaliuresis
decreased plasma volume
166
Studies have shown that OT increased peripheral glucose uptake by GLUT4 independent of...
insulin receptors
167
OT can induce bradycardia, negative inotropy and _____ glucose uptake
increased
