Topic: Endocrine system, growth
Question: What are the growth curves of various body organs after birth? Enumerate the various factors affecting growth?
Click here for Reference Material-This material is informational alone and is not specifically prepared as an answer for any question. Readers may do their own research before finalising diagnoses according to the characteristics unique to each question. Readers should not proceed without cross-referencing with relevant textbooks as well as standard guidelines available.
Growth curves of body organs after birth:
1. Brain: Grows rapidly in infancy. Reaches adult size by age 6 years. Growth driven by dendritic and axonal arborization, synapse formation.
2. Heart: Grows rapidly until puberty. Slows but continues gradual growth into adulthood. Related to increasing body size and workload.
3. Lungs: Grow rapidly in infancy along with thoracic cage. Reach adult size in late teens. Related to increasing oxygen demands.
4. Liver: Grows rapidly in infancy. Reaches maximum size during toddler and preschool years. Slow involution begins during school age years. Size depends on metabolic demands and body size.
5. Thymus: Grows rapidly in infancy. Undergoes involution during adolescence. Size depends on requirements for immune system development.
6. Spleen: Grows rapidly during fetal development and infancy. Reaches maximum size in late childhood or early teens. Size depends on hematologic functions and demands.
7. Bowel: Grows rapidly during infancy to match growth in size and absorptive area for nutrition needs. Growth slows after toddler years but continues gradually into adulthood.
8. Kidneys: Grow rapidly in infancy. Reach adult size by late teens. Growth depends on increasing body size, metabolic demands and waste filtration requirements.
Factors affecting growth can be classified into:
1. Nutritional factors:
– Protein intake: Essential for tissue building and growth hormone secretion. Deficiency impairs growth.
– Calorie intake: Source of energy for growth. Deficiency causes growth failure.
– Micronutrients: Vitamins and minerals like calcium, phosphorus, zinc, etc. Important for tissue growth and development. Deficiencies lead to growth abnormalities.
– Dietary composition: A balanced diet with adequate macronutrients (protein, carbs, fat) and micronutrients is necessary for normal growth.
2. Hormonal factors:
– Growth hormone: Stimulates growth of bones and soft tissues. Deficiency causes growth hormone deficiency and short stature.
– Thyroid hormone: Important for metabolism, development and linear growth. Hypothyroidism leads to growth failure.
– Insulin: Anabolic hormone that promotes tissue building. Deficiency or resistance inhibits growth.
– Cortisol: In excess, can inhibit growth hormone and slow growth. But deficiency also disrupts growth.
– Sex steroids: Androgens and estrogens promote growth spurt and maturation during puberty. Imbalance impacts growth and development.
3. Health factors:
– Chronic illness: Conditions like juvenile arthritis, Crohn’s disease, asthma, etc. can disrupt growth.
– Infections: Recurrent infections stress the body and divert nutrients from growth needs. Impacts growth in children.
– Psychological stress: Prolonged stress leads to elevated cortisol which can slow growth. Stress also affects appetite and nutrition.
4. Genetic factors:
– Determine a person’s final adult height, build and proportions. About 80% of variation in human growth is due to genetics.
– Certain medical conditions like Turner’s syndrome and Down syndrome are also genetically linked and associated with abnormal growth.
5. Environmental factors:
– Living conditions: Affect nutrition, health, and psychological well-being. All of which influence growth and development.
– Socioeconomic status: Impacts nutrition, healthcare access and stress levels. Low SES is linked to poorer growth in children.
– Occupation and activity: Stimulate release of growth promoting hormones. Sedentary lifestyle and lack of activity inhibit growth over the long term.
In summary, growth depends on the complex interplay between all these factors. Impairment at any level can disrupt normal growth through multifactorial effects on development, metabolism, and homeostasis. Treatment may involve managing diet, hormones, medications, lifestyle changes or other interventions targeted at the underlying problem.
