Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Fall 2013 Physiology Endocrine and Renal > Endocrinology of growth > Flashcards

Endocrinology of growth Flashcards

1
Q

Growth hormone releasing hormone is synthesized in what 2 places?

A

The ventromedial hypothalamus and the arcuate nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When GHRH (growth hormone secreting hormone) is secreted, it binds to:

A

receptors on the somatrophs of the anterior pituitary.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Once bound to the receptor on the somatotroph of the anterior pituitary, how does GHRH (growth hormone releasing hormone) act on the pituitary?

A

It stimulates an increase in intracellular cAMP which promotes the synthesis of growth hormone.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The higher the amount of GHRH (growth hormone releasing hormone) released, the more ________ is produced.

A

growth hormone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

The greater the amount growth hormone released, the greater the ________ of the somatotrophs. This can lead to a pituitary tumor.

A

proliferation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The synthesis of growth hormone is inhibited by:

A

somatostatin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where is somatostatin synthesized?

A

in the periventricular nucleus of the hypothalamus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How exactly does somatostatin work at the pituitary level?

A

It binds to receptors on the somatotrophs and inhibits cAMP production, which reduces the secretion of growth hormone by the cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Analogs of somatostatins are useful drugs for:

A

inhibiting excessive cellular growth and division of any cell that has somatostatin receptors present on it’s plasma membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the molecular structure of growth hormone?

A

191 amino acid polypeptide with 2 dissulfide bridges. The dissulfide bridges are imporant because they contribute to the 3D conformation of the mature protein.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Growth hormone is very similar to ________ and ________in structure and therefore creates the possibility that they may interact with each others receptors at times.

A

Prolactin; and human chorionic somatotropin ( a placental hormone with growth-hormone like effects)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What tissue in the body does growth hormone target?

A

virtually any tissue in the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the effect of growth hormone on adipose tissue?

A

It stimulates lipolysis (promotes lean body mass), It decreases the uptake of glucose into the adipocytes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Is growth hormone a stres hormone? and why does it matter?

A

Yes. It will cause elevated blood sugar by increasing glucose production in the liver and prevents muscle and fat from taking up the glucose.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does growth hormone affect the liver?

A

Protein Synthesis: GH stimulates RNA synthesis which stimulates protein synthesis Gluconeogenesis: stimulated to raise blood sugar Somatomedin (IGF-1) increase in production and release.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the effect of growth hormone on muscle?

A

It decreases the amount of glucose uptake by muscle and increases the amount of amino acid uptake to stimulate lean muscle mass by promoting protein synthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does growth hormone affect the internal organs?

A

GH causes increase in RNA and DNA synthesis, which causes increase in protein synthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the effect of oversecretion of growth hormone on the internal organs?

A

Hypertrophy and hyperplasia of the cells. This will increase organ size and function but at a certain point becomes detrimental and prevents normal function of the organ. This can result in death.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the usual cause of death in patients who abuse anabolic steroids?

A

Organ failure from hypertrophy and hyperplasia of organs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the effect of growth hormone on chondrocytes?

A

amino acid uptake is increased and protein sythesis is increased. DNA and RNA levels are increased. Increased collagen production takes place.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the effect of oversecretion of growth hormone on chondrocytes?

A

Hypertrophy and hyperplasia of connective tissue cells. Increased linear growth of tissues if epiphyseal plate it intact (childhood). After plate closes there is an increase in circumference of bones, not length.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Name 6 things that stimulate the release of growth hormone.

A
  1. decrease in glucose, 2. decrease in free fatty acids 3.amino acid increase 4. fasting and prolonged caloric deprivation 5. exercise and stress 6. estrogens and other sex steroids.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How does a decrease in glucose stimulate GH secretion?

A

The hypothalamus detects low glucose. Somatostatin secretion is shut off, GHRH secretion is increased, which leads to an increase in GH, GH has hyperglycemic activity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How does free fatty acid decrease cause GH to increase?

A

The process is the same as with glucose. If blood gluocse levels are normal then fatty acid levels are also able to be maintained at normal levels.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How does a decrease in amino acids cause an elevation in growth hormone?

A

Arginine, in particular, elevates growth hormone. When arginine is give to a patient to test for pituitary function, GH levels rise and then the amino acids are taken up into the tissues for protein synthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How does fasting and prolonged caloric deprivation cause GH rise?

A

similar to low glucose. GH release is triggered, and it has hyperglycemic effects.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How do exercise and stress stimulate GH secretion?

A

Since GH is a stress hormone, it wants to mobilize metabolites in times of need for the body to use.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How do estrogens and sex steroids stimulate growth hormone?

A

communicate with hypothalamus to increase GHRH and somatostatin each to the perfect level to generate the right pulsatile pattern of GH secretion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Describe male growth patterns.

A

Males are bigger because of the way they release growth hormone in the body. Males have a sharp peak of GH about every 4 hours, followed by a very low trough where there is little GH present. The pattern is caused by testosterone, which acts upon the hypothalamus to promote the maximum secretion of GHRH, establishing the peak height of growth hormone release.

30
Q

In the growth pattern of males, which homone is resposible for the very low troughs of GH after testosterone causes the peak?

A

Somatostatin is maximally released in response to testosterone and causes low troughs.

31
Q

Describe the growth pattern of females.

A

The same pulsatile pattern as in males, but the peaks are less well defined or extreme in nature. The pattern is more irregular. Estrogen has milder anabolic effects than testosterone, and does cause release of GH and somatostatin, but at reduced levels.

32
Q

Name 5 situations that inhibit the release of GH.

A
  1. Glucose increase or free fatty acid increase. 2. Obesity 3. Pregnancy 4.Somatostatin 5. Human Growth Hormone
33
Q

How does an increse in glucose or free fatty acids inhibit the release of GH?

A

They enhance the sercretion of somatostatin and inhibit the release of GHRH

34
Q

How do high levels of cortisol inhibit GH?

A

It’s a stress hormone that has hyperglycemic effects. High levels with inhibit GH synthesis and most protein synthesis, leading to a decrease in growth.

35
Q

Does cortisol always inhibit GH?

A

No, at low, normal physiological levels, cortisol will favor the synthesis of growth hormone and other hormone synthesis.

36
Q

How does obesity inhibit the release of growth hormone?

A

by raising blood glucose and free fatty acid levels through excessive intake of food. GH levels are driven down.

37
Q

How does pregnancy inhibit growth hormone?

A

The placenta makes its own version of GH called human chorionic gonadotropin. Which exhibits structural elements similar to both GH and prolactin. It circulates in the maternal bloodstream to the hypthalamus and pituitary and exerts its own version of short loop feedback, which reduces GH secretion from the pituitary.

38
Q

How does GH inhibit GH secretion?

A

short loop feedback of growth hormone on the pituitary and hypothalamus inhibits its own secretion.

39
Q

The normal cycle of growth hormone pulses every _______ hours.

A

4

40
Q

When during a 24 hour cyclce, is the largest pulse of growth hormone released?

A

during deep sleep (about an hour after you fall asleep)

41
Q

The fetus uses what 2 hormones to stimulate growth?

A

IGF-2 and Somatomedin A. Gh is actually low at birth because these 2 have been active.

42
Q

After birth, what 2 hormones are stimulated in the baby?

A

GH and IGF-1

43
Q

GH levels slowly rise during childhood, as the hypthalmic- pituitary unit matures, but skyrocket in puberty when __________________ increase dramatically causing the highest levels of GH in life.

A

sex steroid production

44
Q

After puberty sex steroid production is decreased and growth hormone levels ___________.

A

drop off to the level they will be at for most of the rest of adult life.

45
Q

Why do we need GH during adulthood, if our stature has stopped growing?

A

for organ function and immune function to be maintained.

46
Q

What happens to growth hormone levels during senesence?

A

sex steroid levels decline, which leads to decline in GH release, which leads to loss of lean muscle mass and a gain in weight (adipose).

47
Q

What is one way to decreae the effects of aging?

A

Give the elderly arginine supplements and increase daily exercise. This increases endogenous growth hormone production and maintains lean muscle mass.

48
Q

Put these phases of life in order from most growth hormone to least: Birth Childhood Puberty Adult life Senesence

A

Puberty Childhood Adult Life Birth Senescense

49
Q

If you have too much growth hormone as a child, what pathological condtion will occur and what are some of it’s effects?

A

Giantism and acromegaly. Everything gets bigger. Bones get a larger circumference Jaw gets bigger, hands and feet become thicker. Before the epiphyseal plate closes, massive height occurs.

50
Q

If an adult has too much growth hormone, what pathological condtion can occur?

A

Acromegaly. All of the bones overgrow and get wider. However, the patient does not get taller because the growth plates have already closed.

51
Q

What is the usual cause of pathological release of GH?

A

Macroadenoma of the pituitary

52
Q

If a child does not have enough growth hormone, what pathological conditon ensues?

A

pituitary dwarfism, which is characterized by a failure to grow very tall.

53
Q

What is Laron dwarfism? Does it have high or low levels of GH?

A

dwarfism characterized by normal production of growth hormone by missing or defective growth hormone receptors on the tissues, so the tissues do not respond to it. Also no IGF-1 is produced in the liver, so there is a loss of negative feedback mechanism to the hypothalamus. Because of there is no negative feedback, the pituitary is stimulated to keep on secreting more and more growth hormone. It just never does anything to the tissues.

54
Q

Growth hormone is also known as:

A

somatotropin

55
Q

Although the highest spurts of growth hormone occur during puberty, the highest basal rate of GH occurs during which phase of life?

A

childhood

56
Q

The secretion of growth hormone by the anterior pituitary is regulated by 2 hypothalmic hormones:

A

GHRH and somatostatin

57
Q

Does growth hormone work by direct effect on target tissues?

A

NO. The effects of GH are mediated by the synthesis and release of somatomedins by the liver and by stimulation of somatomedin production in specific target tissues.

58
Q

What is somatomedin?

A

Somatomedin is also known as insulin like growth factor (IGF). The most important one is IGF1, which is produced in the liver and tissues in response to growth hormone.

59
Q

What is the action of the somatomedin IGF1 at the target tissue?

A

binds to receptors on target tissue, producing tyrosine kinase activation, similar to the actions of insulin on its receptor, resulting in intracellular effects.

60
Q

Do growth hormone and IGF1 exert feedback?

A

Yes, they both exert negative feedback on the hypothalamus and anterior pituitary,

61
Q

Does GHRH inhibit its own release?

A

Yes

62
Q

What are the primary roles of GH and IGF1?

A

stimulation of growth and development during childhood and adolescence and regualtion of metabolism and body composition in adults.

63
Q

Name 4 specific actions of IGF1.

A
  1. stimulation of linear growth 2. increase in muscle mass 3. decreased adiposity 4. increase in organ size.
64
Q

The actions of IGF1 involve the stimulation of ______ and _________,

A

RNA and DNA synthesis as well as its more direct effects on cellular amino acid uptake and synthesis of production.

65
Q

Why is growth hormone often referred to as a diabetogenic hormone?

A

because it’s metabolic effects act in opposition to insulin. It elevates blood glucose levels, elvates plasma free fatty acids, and induces insulin resistance and elvated plasma insulin levels.

66
Q

What are some of the symptoms of acromegaly?

A

thickening of the bones of the hands, feet, and jaw. Protrusion of the jaw and brow, enlargement of the tongue (macroglossia), cardiac and renal complications and diabetes.

67
Q

What is the feedback loop of GH?

A

It has a robust short loop negative feedback action on the hypothalamus. It inhibits further release GHRH and somatostatin.

68
Q

What is another name for IGF1

A

Somatomedin C

69
Q

What is the specific estrogen found in females?

A

17 beta estradiol

70
Q
A

Fall 2013 Physiology Endocrine and Renal (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions