Endocrine and Renal Flashcards
(92 cards)
1
Q
What is a hormone?
A
Substance secreted into the blood stream (ductless) to communicate with a distant part of the body
2
Q
How do steroid hormones differ from peptide/amine hormones?
A
Steroid hormones require no membrane receptors and thus no secondary messengers
3
Q
Thyroid hormone is what class of hormone?
A
Steroid
4
Q
Name some common 2nd messengers
A
cAMP, Ca2+, IP3
5
Q
What is the main purpose of the hypothalamus?
A
Integrative center. Takes input from various body systems and releases hormones to either up or down regulate actions at these distant sites.
Also creates releasing factors that act mainly on the pituitary gland.
6
Q
What does the medial preoptic nucleus secrete?
A
Sex hormones
7
Q
What does the PARAventricular nucleus secrete?
A
Oxytocin, ADH
8
Q
What does the supraoptic nucleus secrete?
A
Oxytocin, ADH
9
Q
What does the anterior hypothalamic area control?
A
Metabolism (mostly thermoregulation)
10
Q
What does the PERIventricular nucleus secrete?
A
Somatostatin
11
Q
What does the ventromedial nucleus secrete?
A
GHRH
12
Q
What does the arcuate nucleus secrete?
A
GHRH
13
Q
What is the function of the mamillary bodies?
A
Integrative center
14
Q
What hormones are released from the posterior lobe of the pituitary?
A
Oxytocin, ADH
15
Q
What hormones are released from the anterior lobe of the pituitary?
A
Everything except oxytocin and ADH
16
Q
What type of tissue is the anterior pituitary?
A
Epithelial
17
Q
What type of tissue is the posterior pituitary?
A
Neural
18
Q
Where does the pituitary sit?
A
Sella turcica
19
Q
Where do tumors of the pituitary almost always arise from?
A
Anterior lobe
20
Q
What is the difference between micro and macro tumors of the pituitary
A
Macros grow enough to cause visual disturbances by putting pressure on the optic chiasm
21
Q
The anterior lobe of the p.gland receives what kind of blood supply?
A
Venous, low pressure. No auto-regulation.
22
Q
At what level does the blood-brain barrier not exist?
A
Hypothalamus/Median Eminence
23
Q
What special feature exists to allow passage through the blood-brain barrier?
A
Fenestrations/ “windows to the brain”
24
Q
What area in the pituitary gland houses (1) dense bundles of neurohormone containing fibers and (2) densely packed neurons (less vascular) ?
A
1-anterior 2-posterior
25
What type of system involves synapse causing hormone release into portal vessels for transport to adenohypophysis?
Mediated
26
What type of system involves synapse in the neurohypophysis?
Direct
27
Give an example of a Hypophysiotropic hormone path/cycle.
increased GHRH causing release of GH which will react on the target cell to increase growth.
28
With an increase in ECF (Na) osmolality, how would the Pit.gland respond?
Releases vasopressin/ADH to target kidneys for increased H2O re-absorbtion to balance Na levels
29
Name other factors that illicit a vasopressin/ADH response.
low B/P, stress, ETOH, low fluid vol, pain, Temp. increase, B-adrenergic agonists, various drugs
30
When ACTH release is stimulated by vasopressin/ADH to self inhibit, what other hormone is released into circulation? Where is the other hormone released from?
Cortisol, Renal cortex fasiculata
31
What are some vaso/ADH inhibitors?
Temp. decrease, a-adrenergic agonists, Ethanol, possibly Cortisol and TH
32
What effect does somatostatin have on cAMP?
Decreases
33
Where is somatostatin released from?
PERIventricular nucleus
34
What inhibits prolactin?
Dopamine
35
What does GRH stimulate?
GH
36
What does somatostatin inhibit?
GH, TSH
37
What does TRH stimulate?
TSH, PRL
38
What does GnRH stimulate?
LH, FSH
39
What does CRH stimulate?
ACTH, b-LPH, b-ENDOR
40
Which feedback loop is purely neuro?
Ultra short
41
Which feedback loop is prolactin associated with?
Short
42
How does the ultra short loop release hormone?
In pulsatile waves
43
Which feedback loop requires communication with the peripheral glands?
Long
44
What (6) neurohormones are released from the hypothalamus?
GRH, SS, TRH, DA, GnRH, CRH
45
What (8) hormones are released from the Ant. Pit.?
GH, TSH, PRL, LH, FSH, ACTH, b-LPH, b-ENDOR
46
Give some examples of peptide hormones
insulin, growth hormone
47
Give some examples of steroid hormones
estrogen, testosterone, cortisol (thyroid hormone and vitamin D are steroid like in that they are lipophilic)
48
Give some examples of amine hormones
epinephrine, thyroxine
49
Name a rare example of positive feedback in endocrine secretion.
Menstrual cycle
Estradiol rises until a critical point is reached. This causes a surge in GnRH (from hypothalamus) which leads to LH and FSH (pituitary) surge. This induces ovulation.
Transformation of follicular cells in the corpus luteum ends this positive feedback cycle.
50
Aside from increasing or decreasing hormone levels, how else is the cellular response to hormones regulated?
Up- or down-regulation of membrane receptor sites.
51
ADH and oxytocin are both what kind of hormones?
Nonapeptides (nine amino acid chains)
At high levels they may act on each others receptors
52
How does breastfeeding prevent pregnancy?
Unopposed prolactin (after delivery and with continued breastfeeding) levels have an inhibitory effect on GnRH release and thus reduce levels of LH and FSH
53
What do TSH, LH, and FSH have in common?
Same glycoprotein family. Alpha subunits are identical, beta subunits differ.
54
What do ACTH (arenocorticotropic hormone), MSH (melanocyte stimulating hormone), beta-lipotropin, and beta-endorphin have in common?
All are derived from a single precursor, pro-opiomelanocortin (POMC)
55
Growth hormone is similar to what other two hormones?
Prolactin and human placental lactogen
56
Growth hormone stimulators
Sleep, short-term stress, puberty hormones, starvation, exercise, hypoglycemia
57
Growth hormone inhibitors
Somatostatin, somatomedins, obesity, hyperglycemia, pregnancy
58
Hypothalamic control of GH
GHRH stimulates
| Somatostatin inhibits
59
Somatomedins effect on GH
Produced when GH acts on target tissues
Directly inhibits GH by acting on the pituitary and also stimulates SS release from the hypothalamus
60
GHRH and GH effects on GH secretion
GHRH inhibits itself at the hypothalamus
GH inhibits itself by stimulating SS from the hypothalamus
61
Where are IGFs produced
The liver and to a lesser extent in target tissue
62
What are the direct actions of GH
- glucose uptake into cells
+ lipolysis
+ protein synthesis and lean body mass
+ production of IGFs
63
Actions of GH via IGFs
+ protein synthesis in chondrocytes and thus linear growth (in puberty)
+ protein synthesis and lean body mass
+ protein synthesis in most organs
+ organ size
64
What are the four pathophysiological pathways that involve GH
- Lack of anterior pit. GH
- Hypothalamic dysfunction (decreased GHRH)
- Failure of liver to produce IGFs
- GH receptor deficiency
65
GH excess causes what?
Prepuberty- gigantism
| Postpuberty- acromegaly
66
How is GH excess treated?
SS analogs (octeoride) to inhibit GH secretion
Removal of tumor causing hypersecretion
67
Regulation of prolactin secretion
Tonically inhibited by dopamine. Interruption of this inhibition leads to prolactin secretion.
TRH can also increase prolactin secretion
68
Negative feedback control of prolactin
Prolactin stimulates hypothalamic release of dopamine, which inhibits prolactin secretion
69
Actions of prolactin
+ Milk production
+ Breast development (with estrogen)
- Ovulation by inhibiting GnRH
- Spermatogenesis by inhibiting GnRH
70
Prolactin deficiency
Caused by destruction of anterior pit.
Results in failure to lactate
71
Prolactin excess
Results from hypothalamic lesion (loss of dopamine inhibition) or prolactinomas (hypersecretion)
Results in-
Galactorrhea
Decreased libido
Amenorrhea and failure to ovulate (GnRH inhibited)
72
Treatment for prolactin excess
Bromocriptine (dopamine agonist)
| Prolactinoma removal
73
Factors increasing prolactin secretion
```
Estrogen
Breast-feeding
Sleep
Short-term stress
TRH
Dopamine antagonists
```
74
Factors decreasing prolactin secretion
Dopamine
Bromocriptin (dopamine agonist)
SS
Prolactin (negative feedback)
75
Progesterone has what effect on the hypothalamus?
Increases set point of body temperature
Progesterone is increased during the luteal phase. This results in a slightly elevated basal temperature.
76
Progesterone is secreted during which phase of the menstrual cycle?
Luteal
77
What is responsible for the first (and larger) estrogen peak just prior to ovulation?
What does this result in?
FSH acting on granulosa cells of the ovary. These cells contain aromatase which converts testosterone into 17beta-estradiol.
This creates a positive feedback loop that results in an LH surge which causes ovulation to occur (FSH also surges as a result of this positive feedback)
78
What is responsible for the second (and smaller) estrogen peak several days after ovulation during the luteal phase?
The corpus luteum. The corpus luteum also produces progesterone, which, along with estrogen, prepares the uterus to receive a fertilized egg.
79
When do LH and FSH peak during the menstrual cycle?
At ovulation, typically day 14 of the cycle.
80
The abrupt fall in estradiol and progesterone results in what?
Endometrial sloughing (menses). This begins a new cycle (Day 0-4).
81
During which phase of the menstrual cycle does estrogen exhibit positive feedback characteristics?
Mid-cycle, at the very end of the follicular phase.
82
Name the actions of progesterone
Negative feedback on LH and FSH during the luteal phase
Maintains secretory function of the uterus during the luteal phase
Maintains pregnancy
Raises uterine threshold to contractile stimuli during pregnancy
Participates in breast development
83
Name the actions of estrogen
Positive and negative feedback effects on LH and FSH
Development/maintenance of fallopian tubes, uterus, cervix, and vagina
Development of 2nd sex characteristics in puberty
Breast development
Up-regulation of estrogen, LH, and progesterone receptors
Proliferation/development of ovarian granulosa cells
Maintains pregnancy
Lowers uterine threshold to contractile stimuli during pregnancy
Stimulates secretion of (early pregnancy) and then blocks action of (later pregnancy) prolactin
84
What is the action of progesterone during the follicular phase?
None, progesterone is only active during the luteal phase and pregnancy
85
What prevents the corpus luteum from regressing in the case of pregnancy?
Human chorionic gonadotropin (HCG) which is produced by the growing placenta
Home pregnancy tests detect HCG in the urine
86
What is responsible for estradiol and progesterone production in the first trimester?
Second and third?
The corpus luteum (stimulated by placental HCG, which peaks at 9 weeks)
The placenta produces progesterone, while estrogens are produced by the fetal adrenal gland and are converted into active forms by the placenta
87
What is the major estrogen of the placenta?
EsTRIOL
88
Aside from progesterone and estrogens, what other hormone does the placenta produce? What is this hormone similar to?
Human placental lactogen. It is structurally similar to GH and prolactin.
89
What allows the uterus to become more sensitive to contractile stimuli as pregnancy nears parturition?
As term approaches the estrogen:progesterone ratio increase, making the uterus more sensitive to contractile stimuli.
90
What event allows lactation to begin?
After parturition estrogen and progesterone levels drop abruptly. With the levels of these hormones greatly reduced, the action of prolactin (increasing throughout pregnancy) is no longer blocked
91
What action maintains lactation? Which hormones are involved?
The action of suckling. This stimulates oxytocin (milk expulsion) and prolactin (milk production)
92
What hormone is HCG almost identical to?
LH
