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49 Cards in this Set

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When you think about the hypothalamus you should think about the production of _____ and _____
releasing and inhibitory hormones
Where is the secondary capillary bed in the hypophyseal portal system?
anterior pituitary
How are hormones released into the capillary bed in the Posterior Pituitary?
They are transported from the hypothalamus via EXOPLASMIC transport down the INFUNDIBULAR STALK into the posterior pituitary
What makes neuroendocrine cells unique?
They are simply neurons but they exocytose NT into the blood
T/F
Parafollicular cells are targets of the Anterior Pituitary
False
They are not targets of the anterior pituitary
The follicular cells must have extensive RER and Golgi to make ______ and the vesicles needed for its release.
Thyroglobulin
Thyroglobulin contains a lot of?
Tyrosine
Where does iodination of the tyrosine take place?
lumen of the follicle
When the mature thyroglobulin is endocytosed into the cell, what breaks apart the mature thyroglobulin?
lysosome cleaves the R groups resulting in triiodothyronine and thyroxine
How do T3 & T4 get from the follicular cell and into the blood?
They diffuse
What happens to T4 in the blood?
Once in the blood, we see spontaneous de-iodination of T4 resulting in a 14:6 ratio of T4 - T3
What type of thyroid hormone is considered the active form?
T3
What is T4 used for?
Feedback Inhibition
◊ Inhibits further release of TRF from the hypothalamus
◊ Inhibits further release of TSH from the anterior pituitary
What are the actions of TSH?
TSH increases the synthesis of T3 and T4 by:
1. Stimulating iodine uptake from the blood
2. Stimulating thyroglobulin synthesis
3. Stimulating fusion of the lysosomes with endocytotic vesicles
What does a lack of iodine in the diet result in?
Increase in TRF secretion
Increase in TSH secretion
What does low T3 in children lead to?
Dwarfism & Cretinism
What are the symptoms of Low T3 in adults? (hypothyroidism)
Mentally Sluggish
Physically Sluggish
Decreased BMR (tend to have increased weight gain)
Decreased heat production
Heat Tolerance
What are the symptoms of High T3 in adults?
INCREASE IN BMR**
leading to: increased cardiac output, increased heat production, cold tolerance
If you look at the sequence of amino acids in the beta-LPH portin there are the sequences for:
Endorphins
Beta-MSH
Which two sections of the prohormone must be removed to make the mature form of ACTH?
Cryptic peptide
Beta-lipophilic hormone (beta-LPH)
Which two sections of the prohormone must be removed to make the mature form of ACTH?
Cryptic peptide
Beta-lipophilic hormone (beta-LPH)
What is the source for endorphins in the anterior pituitary?
When the beta-LPH portion is further broken down after breaking away from the ACTH
How is the mature form of GH and Prolactin formed?
Snip off the signal protein that caused it to insert into the lumen of the RER
How is the mature form of TSH, LH and FSH formed?
All involve glycosylation
What is the active culprit in producing the effects associated with GH?
Somatomedins
(have a structure similar to insulin)
What is the cause of Pituitary Dwarfism?
Low GH
T/F
Pituitary dwarfism can be treated by administering HGH at any stage of life.
False
HGH will only be effective if administered before puberty.

*the earlier you start treatment, the more normal the height of the adult
*must start before the long bones fuse
What are two major sytems that are affected by HGH?
Bone
Muscle
How does HGH affect bone?
1) stimulates chondroblast activity (elongation in epiphyseal plates)
2) stimulates bone lengthening
3) stimulates bone thickness
How does HGH affect muscle?
Increases net protein synthesis (non-polypeptide kind of effect because it is a change in gene expression)
How does HGH cause an increase in net protein synthesis?
1) decreasing protein catabolism (inhibits proteolytic enzymes)-can be activated by secondary messengers
2) increased amino acid uptake-can be activated by secondary messengers
3) increased mRNA (alters gene expression)-the non-polypeptide effect
T/F
There is a surge of GH at puberty.
False
GH levels stay relatively constant over our life span
What does Low GH in adults cause?
No big problems
What does High GH in adults cause?
1)Diabetes-like symptoms
*increased blood glucose
*increased blood free fatty acids
2)Acromegaly
What causes GH levels to peak at 2am and bottom out at 2 pm?
Diurnal Rhythm
Why is the diurnal rhythm helpful for growth?
most of the growing of bone and muscle will be done late at night, where there are less demands from the rest of our body.
What causes release of GHIH from the hypothalamus?
1) Decreased AA and Increased blood glucose
2) Somatomedins (presence of somatomedins causes release of GHIH (somatostatins)
What is another term for somatostatins?
GHIH
What inhibits the release of GHRH from the hypothalamus?
HGH
Which hormone levels stay fairly constant over the course of days to weeks, but they are increased in the winter and decreased in the summer?
T3 levels
What provides the negative feedback to the hypothalamus and the thyrotrophs in the anterior pituitary?
T4
What type of feedback occurs when the primary hormones feed back to inhibit the hypothalamus from releasing more RF?
Short loop feedback
Which of the following would be expected following ablation of the anterior pituitary?

a)Lose of insulin secretion
b)Loss of glucagon secretion
c)Increased sensitivity to insulin
d)Increased sensitivity to epinephrine
e)Loss of ability to metabolize fat
Increased sensitivity to insulin
The release of which of the following may be associated with endorphin and enkephalin release?

a)Somatomedin
b)Adrenal corticotrophic hormone
c)Thyroid stimulating hormone
Cortisol
d)Somatostatin
Adrenal corticotrophic hormone
Which of the following is released in response to elevated blood glucose or low amino acid levels in plasma?

a)Somatomedin
b)Adrenal corticotrophic hormone
c)Thyroid stimulating hormone
d)Cortisol
e)Somatostatin
e)Somatostatin
Growth Hormone (HGH) in a normal individual

a)Is at highest levels during puberty
b)Is at highest levels at night
c)Promotes closure of epiphyseal plates
d)A and B
e)B and C
b)Is at highest levels at night
Which of the following stimulates release of somatomedin by the liver?

a)Growth hormone
b)Thyroid hormone
c)Prostaglandins
d)Releasing factors
e)More than one of the above
a)Growth Hormone
Which of the following is FALSE regarding Growth Hormone?

a)GH increases chondroblast activity
b)GH is stimulated by somatostatin
c)GH enhances protein synthesis
d)GH is stimulated by low plasma glucose levels
e)GH is secreted by the adenohypophysis
b) GH is stimulated by somatostatin

THIS IS INCORRECT GH IS STIMULATED BY GHRH
Which of the following occurs as plasma aldosterone increases?

a)Urinary output of both Na+ and K+ decreases
b)Urinary output of both Na+ and K+ increases
c)Elevated Na+ and decreased K+ in plasma
d)Decreased Na+ and elevated K+ in plasma
e)Osmotic diuresis
c)Elevated Na+ and decreased K+ in plasma