Human Growth and Development: Hormonal Control

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Questions and Answers

How does the interplay between genetics and environmental factors influence an individual's growth trajectory during childhood, and what are some specific examples of each?

Genetic factors provide the blueprint for growth potential, while environmental factors such as nutrition and exposure to toxins can either facilitate or impede this potential. For example, genetic predisposition to height can be stunted by malnutrition.

Explain the significance of the adolescent growth spurt in humans compared to other animal species, highlighting its unique characteristics and potential evolutionary advantages.

The adolescent growth spurt in humans is more pronounced and prolonged than in many other species. This extended period of growth may allow for greater cognitive development and social learning, ultimately enhancing survival and reproductive success.

Describe how the transition from fetal to newborn circulation involves a series of coordinated changes. What would happen to the newborn circulation if the ductus arteriosus failed to close?

Fetal circulation bypasses the lungs through the foramen ovale and ductus arteriosus. Postnatally, these close as pulmonary circulation is established. Failure of the ductus arteriosus to close (patent ductus arteriosus) would result in mixing of oxygenated and deoxygenated blood, leading to circulatory compromise.

What are the main physiological purposes of fetal breathing movements, and how do they contribute to the development of the respiratory system before birth?

Fetal breathing movements help to develop the respiratory muscles and regulate lung fluid volume. These movements expose the lungs to pressure gradients, preparing them for efficient gas exchange after birth. Signup and view all the answers

Explain the concept of 'metastatic aging' and how it links the aging process in one tissue or organ to the decline in function of distant tissues or organs.

Metastatic aging refers to the idea that aging-related changes in one tissue can have systemic effects, accelerating aging in other tissues. For example, senescent cells in one organ can release factors that promote inflammation and dysfunction in distant organs. Signup and view all the answers

Describe the key differences in the rate of age-dependent physiological decline between the cardiovascular and neurological systems, and what are the potential implications of these differences for overall health?

The cardiovascular system tends to decline relatively early in aging, increasing risk of heart disease and stroke. Neurological decline occurs later, but can have devastating effects on cognitive function and mobility. Signup and view all the answers

Explain how cortisol acts as a 'master regulator' during the transition from fetus to newborn, and provide specific examples of its effects on different organ systems.

Cortisol promotes lung maturation, stimulates surfactant production, and enhances metabolic function. For example, in the lungs, it promotes alveolar development and surfactant synthesis. Signup and view all the answers

How do maternal and paternal factors independently and jointly influence the growth and development of their offspring?

Maternal factors, such as nutrition and health during pregnancy, directly impact fetal development. Paternal factors, like sperm quality and epigenetic inheritance, can contribute to offspring health and developmental trajectories. Signup and view all the answers

Explain the roles of LH and FSH in both males and females during puberty, highlighting any sex-specific differences in their effects.

In females, LH stimulates ovulation and progesterone production, while FSH stimulates follicle development and estrogen production. In males, LH stimulates testosterone production, while FSH supports spermatogenesis. Signup and view all the answers

Compare and contrast the mechanisms by which growth hormone (GH) and thyroid hormones (TH) influence bone growth during childhood, and discuss the potential consequences of deficiency in either hormone.

GH promotes bone growth by stimulating IGF-1 production, which enhances chondrocyte proliferation and bone formation; TH promotes bone maturation and mineralization. Deficiency in either hormone can lead to impaired growth and skeletal abnormalities. Signup and view all the answers

Explain why lung fluid clearance is critical for the survival of the newborn. How is this process regulated?

Lung fluid clearance allows for efficient gas exchange by replacing fluid with air. It's regulated by epinephrine and sodium channels that absorb the lung fluid. Signup and view all the answers

Define surfactant and explain how its physical properties benefit the lungs of the newborn.

Surfactant is a mixture of lipids and proteins that reduces surface tension in the alveoli. This prevents alveolar collapse, reduces the work of breathing, and improves lung compliance. Signup and view all the answers

Describe the process of 'telomere attrition or shortening' and explain its role in biological aging. What are the potential consequences of critically shortened telomeres?

Telomere attrition refers to the shortening of telomeres with each cell division. Critically shortened telomeres can trigger cellular senescence and lead to genomic instability, contributing to cellular dysfunction and aging. Signup and view all the answers

Describe the main changes in the brain during puberty and adolescence, focusing on structural and functional changes in the prefrontal cortex.

During puberty, the brain undergoes significant remodeling, including increased synaptic pruning and myelination, particularly in the prefrontal cortex. These changes enhance executive functions, decision-making, and impulse control. Signup and view all the answers

What challenges are faced by the lungs of a preterm baby with respect to the transition from fetal to air breathing?

Preterm babies often have underdeveloped lungs with insufficient surfactant production. This leads to difficulty in inflating the lungs, increased risk of respiratory distress syndrome (RDS), and impaired gas exchange. Signup and view all the answers

Explain the concept of 'permissive hormone' using thyroid hormone as an example.

A permissive hormone allows another hormone to exert its full effect. Thyroid hormone, for example, has a permissive effect on growth hormone, allowing GH to effectively promote growth and development. Signup and view all the answers

Define 'epigenetics' and briefly describe its role in biological aging, including specific examples of epigenetic modifications.

Epigenetics refers to changes in gene expression that do not involve alterations to the underlying DNA sequence. DNA methylation and histone modification can accumulate with age, leading to altered gene expression patterns and contributing to aging. Signup and view all the answers

How does improved health care influence the average human lifespan, and what are the potential implications for biological aging and age-related disability?

Improved health care extends lifespan by reducing mortality from disease; however, it may not necessarily slow biological aging. This can lead to an increased period of age-related disability, as individuals live longer with age-related conditions. Signup and view all the answers

Provide a concise definition of 'mitochondrial dysfunction' and describe its role in biological aging. What are the potential consequences of impaired mitochondrial function?

Mitochondrial dysfunction refers to impaired energy production, increased oxidative stress, and altered apoptosis regulation. This can lead to reduced cellular function, increased inflammation, and accelerated aging. Signup and view all the answers

How does cellular senescence contribute to biological aging, and what role do hematopoietic stem cells play in this process?

Cellular senescence is a state of irreversible cell cycle arrest that contributes to tissue dysfunction and aging. Senescent hematopoietic stem cells, for example, can impair blood cell production and contribute to immune dysfunction. Signup and view all the answers

Flashcards

Human Lifespan Phases

Prenatal, infancy, childhood, adolescence, adulthood, senescence.

Factors Controlling Growth

Nutritional, environmental, genetic, and mechanical factors control growth and development.