Growth and Development

Question 1

What is growth?

Answer 1

a complex coordinated sequence of events beginning at conception and continuing until the end of puberty, characterized by increases in size, cell number, and intracellular volume.

Question 2

What continues to grow into adulthood even after height stops increasing?

Answer 2

Skin, nails, and hair.

Question 3

What are the three cellular changes that characterize growth?

Answer 3

Hypertrophy (increase in size), hyperplasia (increase in number), and increase in intracellular material.

Question 4

What are the four phases of growth?

Answer 4

1. Intrauterine, 2. Infancy, 3. Early Childhood, 4. Pubertal Growth Spurt.

Question 5

What drives growth in the intrauterine phase?

Answer 5

Genetic constitution, nutrition, and placental function.

Question 6

What drives growth in infancy?

Answer 6

Nutritional factors.

Question 7

What hormone influences early childhood growth?

Answer 7

Growth Hormone (GH).

Question 8

What hormones regulate the pubertal growth spurt?

Answer 8

GH and sex hormones.

Question 9

When is foetal growth at its peak?

Answer 9

Between weeks 16-20 of gestation.

Question 10

When does peak foetal weight gain occur?

Answer 10

Around week 34 of gestation.

Question 11

What happens in early gestation prior to peak growth?

Answer 11

Morphogenesis – differentiation and specialisation of cells into tissues and organs.

Question 12

When does fat deposition occur in the foetus?

Answer 12

In the last weeks of gestation.

Question 13

When do girls reach peak height velocity?

Answer 13

Around 13 years.

Question 14

When do boys reach peak height velocity?

Answer 14

Around 15–16 years.

Question 15

When does average height growth cease in boys and girls?

Answer 15

Boys ~17.5 yrs, Girls ~15.5 yrs (±2 years).

Question 16

What is development?

Answer 16

Increase in complexity due to nervous system maturation, involving qualitative functional changes.

Question 17

When is development most rapid?

Answer 17

In early life.

Question 18

What is apoptosis?

Answer 18

Genetically regulated cell death ensuring balance between proliferation and death.

Question 19

Give an example of apoptosis during development.

Answer 19

Removal of webs between fingers, and formation of hollow organs like the heart.

Question 20

What is senescence?

Answer 20

Age-related physiological decline after growth has ceased, affecting homeostatic mechanisms.

Question 21

What causes changes during senescence?

Answer 21

Decline in sex hormones and accumulated molecular changes.

Question 22

How do bones grow during childhood?

Answer 22

Through proliferation and hypertrophy of chondroblasts under growth plates.

Question 23

When does vertebral growth cease?

Answer 23

Around 30 years of age.

Question 24

Where is Growth Hormone (GH) secreted from?

Answer 24

Anterior pituitary gland.

Question 25

What mediates the indirect effects of GH?

Answer 25

Insulin-like Growth Factors (IGF-I and IGF-II).

Question 26

What hormone stimulates IGF-I secretion after birth?

Answer 26

Growth Hormone (GH).

Question 27

What is the main IGF active before birth?

Answer 27

IGF-II.

Question 28

Name other hormones important in growth besides GH.

Answer 28

Thyroid hormones (T3/T4), Insulin, Prolactin, Placental Lactogen, Vitamin D, PTH, Sex hormones, Glucocorticoids.

Question 29

When does foetal thyroid hormone secretion start?

Answer 29

Around 15–20 weeks gestation.

Question 30

What is the result of congenital hypothyroidism?

Answer 30

Cretinism – severe mental and physical retardation.

Question 31

How is congenital hypothyroidism screened?

Answer 31

Via Guthrie test detecting high TSH.

Question 32

What hormone promotes linear bone growth and skeletal maturation?

Answer 32

Thyroid hormone (T3 and T4).

Question 33

What causes achondroplasia?

Answer 33

FGFR3 mutation → ↓ endochondral ossification and chondrocyte proliferation.

Question 34

What is acromegaly?

Answer 34

GH hypersecretion in adults, causing soft tissue overgrowth and organomegaly.

Question 35

What is pituitary dwarfism?

Answer 35

GH deficiency in childhood causing proportionate short stature.

Question 36

What is Laron dwarfism?

Answer 36

GH receptor defect with high GH but low IGF-I; treated with recombinant IGF-I.

Question 37

What is the most common cause of growth failure worldwide?

Answer 37

Malnutrition.

Question 38

What nutrient is especially critical for growth?

Answer 38

Protein.

Question 39

What does FGFR3 mutation cause? 3

Answer 39

1. decreased endochondral ossification, 2. inhibited proliferation of chondrocytes in growth plate cartilage, 3. decreased cellular hypertrophy, and decreased cartilage matrix production.

Question 40

common height of adult main in achondroplasia?

Answer 40

125cm

Question 41

common height of female with achondroplasia?

Answer 41

120cm

Question 42

What causes acromegaly?

Answer 42

GH hypersecretion, most often due to a pituitary somatotroph adenoma.

Question 43

effects in children vs adults of acromegaly?

Answer 43

Children: Excess GH → Gigantism (↑ linear growth) Adults: Acromegaly (enlarged extremities & soft tissue)

Question 44

Is nutritional Growth Failure reversible?

Answer 44

yes - with well balanced dit and protein rich diet