Normal Growth Physiology

Question 1

Where is GH released?

Answer 1

The anterior pituitary

Question 2

What is another name for GH?

Answer 2

Somatotrophin

Question 3

What is meant by species-speciifc?

Answer 3

It is not possible to used GH of non-human species in the treatment of deficiencies

Question 4

What does GH require the permissive action of?

Answer 4

Thyroid hormones and insulin

Question 5

What type of hormones is GH?

Answer 5

Peptide hormone

Question 6

What % of GH hormone travels bound to protein?

Answer 6

50%

Question 7

What is GH necessary for?

Answer 7

Growth and development

Question 8

What is growth in the foetal period and first 8-10 months predominated by?

Answer 8

nutritional Intake

Question 9

What is growth after 10 months predominated by?

Answer 9

GH

Question 10

How is growth promoting of GH mediated ?

Answer 10

Through stimulation of both cell size and cell diviion

Question 11

How is the effect of GH indirect?

Answer 11

As it is achieved through the action of an intermediate

IGF-1

Question 12

What does IGF-1 do?

Answer 12

Mediates the action of GH

Question 13

What does IGF-1 have a similar action to?

Answer 13

Insulin

Question 14

How is the latter action of IGF-1 limited?

Answer 14

As it is limited to glucose uptake in muscle

Question 15

Where is IGF-1 secreted from?

Answer 15

Liver

Question 16

What is IGF-1 secreted in response to?

Answer 16

GH release from the anterior pituitary

Question 17

How does IGF-1 control the release of GH from the Anterior P?

Answer 17

Through a negative feedback loop

Question 18

How does IGF exhibit a negative feedback on t GH release?

Answer 18

Inhibits GHRH

Simutlates GHIH

Question 19

What is the effect of GH and IGF on bone?

Answer 19

1. GH stimulates chondrocyte precursor cells (prechondrocytes) in the epiphyseal plates to differentiate into chondrocytes.
2. During the differentiation, the cells begin to secrete IGF-I and to become responsive to IGF-I
3. IGF-I then acts as an autocrine or paracrine agent to stimulate the differentiating chondrocytes to undergo cell division and produce cartilage, the foundation for bone growth.

Question 20

When does the epiphyseal plate close?

Answer 20

During adolescence

Question 21

What does the epiphyseal plate close under the influence of?

Answer 21

Sex steroid hormone

Question 22

What happens once the peiphyseal plate closes?

Answer 22

No further longitudinal growth is possible

Question 23

What are the direct effects of GH?

Answer 23

Increases gluconeogenesis by the liver
Reduces the ability of insulin to stimulate glucose uptake by muscle and adipose tissue
Makes adipocytes more sensitive to lipolytic stimuli
Increases muscle, liver and adipose tissue amino acid and protein synthesis

Question 24

Why is GH said to be diabetogenic?

Answer 24

Because it increases blood glucose

Question 25

How is GH release controlled?

Answer 25

By hypothalamus secreting GHRH and GHIH

Question 26

How does GH in the body vary throughout the day?

Answer 26

Varied dramatically throughout the day

Question 27

What type of hormones are GH and IGF-1?

Answer 27

Peptide

Question 28

What is the 24 hour mean of GH in adults and in children?

Answer 28

Adults - 2-4ng/ml | Children 5-8 ng/ml

Question 29

When is GH secretion approximately 20x increases?

Answer 29

In children during stages of deep delta sleep

Question 30

What is unusual about GH transport int he blood considering it is a peptide hormone?

Answer 30

It travels bound to carrier protein which is unusual for peptide hormones

Question 31

What causes fluctuations of GHRH and GH?

Answer 31

Spontaneously and in response to specific stimuli

Question 32

What stimuli increase GHRH secretion?

Answer 32

``` Actual or potential decrease in energy supply to cells Increased amino acids in the plasma Stressful stimuli Delta sleep Oestrogen and androgens ```

Question 33

Which stimuli increase GHIH secretion?

Answer 33

Glucose FFA REM sleep Cortisol

Question 34

What are the 3 factors that affect growth?

Answer 34

Hormones Nutrition Genetics

Question 35

Which hormones affect growth?

Answer 35

``` GH IGF-1 Thyroid hormones Androgens Oestrogen Glucocorticoids Insulin ```

Question 36

When does GH kick in?

Answer 36

About 10 months old

Question 37

Where do babies get their thyroid hormones from?

Answer 37

Mothers

Question 38

Which hormones dominate growth spurts in teenagers?

Answer 38

Sex hormones

Question 39

What are thyroid hormones essential for?

Answer 39

Normal growth | Especially for the development of the nervous system in utero and in early childhood

Question 40

What is cretinism?

Answer 40

Condition where children are hypothyroid from birth

Question 41

Why does cretinism cause retarded growth?

Answer 41

Because there is the loss of TH's permissive action on GH

Question 42

What are GH levels in cretinism

Answer 42

Normal | Just there is no permissive action

Question 43

When are the 2 periods of rapid growth in humans?

Answer 43

Infancy | Puberty

Question 44

How do androgens and oestrogen increase growth during puberty?

Answer 44

They produce spikes of GH and IGF-1

Question 45

Which hormones terminate growth?

Answer 45

Androgens and oestrogen

Question 46

What is usually the cause of hypersecretion of GH?

Answer 46

Endocrine tumours

Question 47

What causes giantism?

Answer 47

Excess GH due to a pituitary tumour BEFORE the epiphyseal plates of long bones have closed

Question 48

What causes acromegaly?

Answer 48

Excess GH due to a pituitary tumour AFTER epiphyseal plates have sealed

Question 49

Why is there no longitudinal growth in acromegaly?

Answer 49

Because the epiphyseal plate of long bones has closed/sealed