Growth and Development Flashcards
What is growth?
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.
What continues to grow into adulthood even after height stops increasing?
Skin, nails, and hair.
What are the three cellular changes that characterize growth?
Hypertrophy (increase in size), hyperplasia (increase in number), and increase in intracellular material.
What are the four phases of growth?
- Intrauterine, 2. Infancy, 3. Early Childhood, 4. Pubertal Growth Spurt.
What drives growth in the intrauterine phase?
Genetic constitution, nutrition, and placental function.
What drives growth in infancy?
Nutritional factors.
What hormone influences early childhood growth?
Growth Hormone (GH).
What hormones regulate the pubertal growth spurt?
GH and sex hormones.
When is foetal growth at its peak?
Between weeks 16-20 of gestation.
When does peak foetal weight gain occur?
Around week 34 of gestation.
What happens in early gestation prior to peak growth?
Morphogenesis – differentiation and specialisation of cells into tissues and organs.
When does fat deposition occur in the foetus?
In the last weeks of gestation.
When do girls reach peak height velocity?
Around 13 years.
When do boys reach peak height velocity?
Around 15–16 years.
When does average height growth cease in boys and girls?
Boys ~17.5 yrs, Girls ~15.5 yrs (±2 years).
What is development?
Increase in complexity due to nervous system maturation, involving qualitative functional changes.
When is development most rapid?
In early life.
What is apoptosis?
Genetically regulated cell death ensuring balance between proliferation and death.
Give an example of apoptosis during development.
Removal of webs between fingers, and formation of hollow organs like the heart.
What is senescence?
Age-related physiological decline after growth has ceased, affecting homeostatic mechanisms.
What causes changes during senescence?
Decline in sex hormones and accumulated molecular changes.
How do bones grow during childhood?
Through proliferation and hypertrophy of chondroblasts under growth plates.
When does vertebral growth cease?
Around 30 years of age.
Where is Growth Hormone (GH) secreted from?
Anterior pituitary gland.
What mediates the indirect effects of GH?
Insulin-like Growth Factors (IGF-I and IGF-II).
What hormone stimulates IGF-I secretion after birth?
Growth Hormone (GH).
What is the main IGF active before birth?
IGF-II.
Name other hormones important in growth besides GH.
Thyroid hormones (T3/T4), Insulin, Prolactin, Placental Lactogen, Vitamin D, PTH, Sex hormones, Glucocorticoids.
When does foetal thyroid hormone secretion start?
Around 15–20 weeks gestation.
What is the result of congenital hypothyroidism?
Cretinism – severe mental and physical retardation.
How is congenital hypothyroidism screened?
Via Guthrie test detecting high TSH.
What hormone promotes linear bone growth and skeletal maturation?
Thyroid hormone (T3 and T4).
What causes achondroplasia?
FGFR3 mutation → ↓ endochondral ossification and chondrocyte proliferation.
What is acromegaly?
GH hypersecretion in adults, causing soft tissue overgrowth and organomegaly.
What is pituitary dwarfism?
GH deficiency in childhood causing proportionate short stature.
What is Laron dwarfism?
GH receptor defect with high GH but low IGF-I; treated with recombinant IGF-I.
What is the most common cause of growth failure worldwide?
Malnutrition.
What nutrient is especially critical for growth?
Protein.
What does FGFR3 mutation cause? 3
- decreased endochondral ossification,
- inhibited proliferation of chondrocytes in growth plate cartilage,
- decreased cellular hypertrophy, and decreased cartilage matrix production.
common height of adult main in achondroplasia?
125cm
common height of female with achondroplasia?
120cm
What causes acromegaly?
GH hypersecretion, most often due to a pituitary somatotroph adenoma.
effects in children vs adults of acromegaly?
Children: Excess GH → Gigantism (↑ linear growth)
Adults: Acromegaly (enlarged extremities & soft tissue)
Is nutritional Growth Failure reversible?
yes - with well balanced dit and protein rich diet
