01d: GH and Growth

Question 1

T/F: GH is the single most important hormone required for post-natal growth.

Answer 1

True

Question 2

T/F: Attainment of adult size is absolutely dependent on GH.

Answer 2

True

Question 3

GH exerts its effect through mediation by the following chemical messengers: Star the most important

Answer 3

1. IGF-I*
2. IGF-II
3. Somatomedin C

Question 4

In general, plasma concentrations of (X) reflect availability of (Y) hormone and/or the rate of growth.

Answer 4

X = IGF-I
Y = GH

Question 5

Children whose growth is slower than average have lower concentrations of (X). Administration of (Y) can restore growth to nearly normal.

Answer 5

X = Y = IGF-I

Question 6

IGF is which type of receptor?

Answer 6

Tyr kinase

Question 7

T/F: IGF-I stimulates cell growth in cartilage and many other tissues.

Answer 7

False - cell proliferation in those tissues

Question 8

T/F: IGF-I primarily exerts its effects locally (autocrine/paracrine) and has only minor role in circulation.

Answer 8

True

Question 9

GH acts directly on (X) to promote IGF-I production. (Y) is the main source of IGF-I in blood.

Answer 9

X = liver and peripheral tissues
Y = liver

Question 10

T/F: Both IGF-I and II are present in blood at relatively high concentrations until adult life (after puberty).

Answer 10

False - high throughout life

Question 11

T/F: IGF-I and II circulate in blood, bound to IGF binding proteins.

Answer 11

True

Question 12

GH is secreted (tonically/episodically), with the largest secretion normally associated with (X). List some other factors that induce its secretion.

Answer 12

Episodically (bursts);
X = early hours of sleep

Stress, X, fasting, low glucose

Question 13

Changes in GH secretion with age primarily reflects changes in (frequency/magnitude) of pulses.

Answer 13

Magnitude

Question 14

T/F: In the absence of GHRH, GH secretion completely ceases.

Answer 14

True

Question 15

Plasma IGF-(I/II) plays important role in (stimulating/inhibiting) GH secretion by (stimulating/inhibiting) (X).

Answer 15

I;
Inhibiting;
Inhibiting;
X = GHRH effect on pituitary

Question 16

(X) growth is stunted in children suffering from unremediated hypothyroidism. This is primarily due to (increase/decrease) in (Y) synthesis.

Answer 16

X = linear;
Decrease;
Y = GH

Question 17

T/F: During fetal growth, it’s actually thyroid hormones, not GH, that serves as growth-promoting hormone.

Answer 17

False - Insulin!

Question 18

The (X) organ cell mass is especially important in embryo/fetus, since it produces the growth-promoting hormone during fetal life. This cell mass is determined by locally produced (Y).

Answer 18

X = pancreatic (insulin)
Y = IGF-II (predominant IGF in embryo/fetus tissue)

Question 19

T/F: Insulin concentrations are not as important/effective in maintaining normal growth postnatally.

Answer 19

False - optimal concentrations still required to maintain normal growth

Question 20

T/F: Unlike IGF-I and II, Insulin doesn’t require plasma-binding protein.

Answer 20

True

Question 21

When it comes to adolescent growth spurt, (X) hormones are responsible. Specifically, they promote which two key changes?

Answer 21

X = gonadal sex steroids (primarily estrogens)

1. Linear growth
2. Closure of epiphyses

Question 22

T/F: Hypogonadal individuals tend to have stunted growth and shorter limbs.

Answer 22

False - opposite (tall with long arms/legs)

Question 23

T/F: During growth spurt, there isn’t normally a significant change in plasma IGF-I and GH concentrations.

Answer 23

False! Spike in both (responsible for increase in height)

Question 24

Observations have shown that (estrogens/androgens) are responsible for pubertal growth. This is because (M/F) children lacking (X) don’t experience this growth.

Answer 24

Estrogens;
Both M and F
X = aromatase enzyme

Question 25

The short stature of Pygmies is caused by (high/low) levels of (X), specifically during which stage of (pre/post)-natal life?

Answer 25

Low (genetic inability to produce);
X = IGF-I
Puberty (GH and IGF-I levels normal before that)

Question 26

(X), although required for synthesis of GH, will decrease GH secretion in excess.

Answer 26

X = glucocorticoids

Question 27

Mid-parental height is calculated in which way? How does that number change depending on if child is M/F?

Answer 27

Average of father and mother height;

Add 2.5 in for M and subtract for F

Question 28

Mid-parental and Target Height: Limits of (X) SD above/below target height are displayed.

Answer 28

X = 2

Question 29

(X) is a phenomenon when child’s growth curve deviates from normal family pattern, but eventually catches up with cohort (late puberty).

Answer 29

X = constitutional delay

Question 30

GH hypersecretion, caused by (X) tumor, will cause (Y) if arises before puberty.

Answer 30

X = pituitary;
Y = gigantism (due to bone lengthening)

Question 31

GH hypersecretion, caused by (X) tumor, will cause (Y) if arises after puberty.

Answer 31

X = pituitary
Y = acromegaly (disfiguring bone thickening; bones can't grow anymore, so expand)

Question 32

GH excess can be treated with analog to (X).

Answer 32

X = somatostatin