Childhood Growth Flashcards
List 6 conditions of body proportions.
1 - Short trunk dysplasia.
2 - Short limb dysplasia.
3 - Rhizomelia (short arms and thighs but not forearm and leg).
4 - Mesomelia (short forearms and legs but not arms and thighs).
5 - Acromelia (short hands and feet).
6 - Asymmetry.
List 2 changes in growth between infancy and childhood.
1 - Growth rate decreases from infancy to childhood.
2 - In infancy, growth is dependent on nutrition, whereas in childhood, growth is dependent on hormones (growth hormone and thyroid hormone).
What causes the growth spurt in teenagers?
The growth spurt is caused by sex hormones (oestrogen in females and testosterone in males).
What causes growth to end?
- Growth ends with the fusion of epiphyses of long bones.
- Fusion of epiphyses is due to the influence of oestrogen in both boys and girls.
- In boys, the oestrogen is derived from aromatase converting testosterone to oestrogen.
Why is the average height for men greater than for women?
The average height for men is greater than for women because the growth spurt in the teenage years is greater for males than for females.
*Growth preceding the growth spurt is similar for males and females.
List 6 determinants of growth.
1 - Growth-promoting hormones.
2 - Genetics.
3 - Quality and duration of pregnancy.
4 - Nutrition.
5 - Health of organ systems.
6 - Psychosocial environment.
Where in the body does growth occur?
Growth occurs at growth plates (at the epiphyses of long bones).
List the processes that occur during growth.
1 - Chondrogenesis.
2 - Hypertrophy of chondrocytes.
3 - Osteogenesis.
Define chondrogenesis.
Chondrogenesis is the process by which cartilage is formed from condensed mesenchyme tissue, which differentiates into chondrocytes and begins secreting the molecules that form the extracellular matrix of the cartilage.
Define osteogenesis.
Osteogenesis is the replacement of a cartilaginous template with bone.
Why do chronic inflammatory diseases impair growth?
Chronic inflammatory disease impair growth because inflammatory mediators inhibit the growth of chondrocytes.
What is osteochondrodysplasia?
- Osteochondrodysplasia is a primary growth plate abnormality resulting from a genetic defect of cartilage and bone growth.
- It causes abnormal shapes and sizes of the skeleton, as well as disproportion of the long bones, spine and head.
List 5 causes of secondary growth disorders that cause reduced growth.
1 - Malnutrition.
2 - Chronic disease.
3 - Intrauterine growth restriction.
4 - Endocrine disorders (more in the next card).
5 - Psychosocial factors.
List 5 endocrine disorders that cause reduced growth.
1 - Growth hormone deficiency.
2 - IGF-1 deficiency.
3 - Hypothyroidism.
4 - Cushing’s syndrome.
5 - Pseudohypoparathyroidism (a genetic condition in which the body fails to respond to parathyroid hormone, which is produced in normal quantities).
6 - Rickets (vitamin D deficiency).
Describe the regulation of growth hormone secretion.
1 - The hypothalamus releases somatostatin and growth-hormone releasing hormone (GHRH).
- Somatostatin, growth hormone and IGF-1 have a negative feedback effect on GHRH release at the hypothalamus.
- The target of GHRH and somatostatin is the pituitary, where the effect of GHRH is positive and the effect of somatostatin is negative.
2 - The pituitary releases growth hormone.
- Both growth hormone and somatostatin have a negative feedback effect on the release of growth hormone at the pituitary.
- Its target is the liver (promoting IGF-1 secretion) and the bone (promoting growth).
3 - The liver secretes IGF-1.
- IGF-1 has a negative feedback effect on its release at the liver.
- Its target is the bone, where it causes growth.