Chapter 3: Physical Development Flashcards
What are growth norms?
expectations for typical gains and variations in height and weight for children based on chronological age and (usually) ethnic background
What do growth norms tell us?
- tells us if the child’s growth is normal and on-track with their peers
- tells us if they’re healthy in comparison to kids their age
Describe growth in infancy.
- most rapid growth of lifespan aside from embryonic period
- lose weight when born, quickly regain it, then go through growth spurts
- head is 25% of the length of the body
Describe growth in early and middle childhood.
- growth slows down considerably
- individuals body portions are much more like that of an adult
- as they’re growing, their proportions grow into the size of their head
How do genetics influence physical development in infancy and childhood?
by stipulating the amount of hormones that are released
How do hormones influence physical development in infancy and childhood?
influence cells, and are the way in which genetic instructions are transformed into physical development
How does the environment influence physical development in infancy and childhood?
good nutrition, health care, and clean water = influences better growth
What is puberty?
biological transition to adulthood in which adolescents mature physically and become capable of reproduction
When is puberty complete?
puberty is not complete until reproductive organs are all functional
What is the primary influence of physical development?
puberty
What is puberty regulated by?
regulated by hormones that are part of Hypothalamus-Pituitary-Gonadal Axis (HPG) → causes individuals to go through puberty
When does puberty start?
can start at 8 or 9 years old
girls typically start earlier than boys
How long does puberty take?
whole process takes about 4 years to complete
What is an adolescent growth spurt?
rapid gain in height and weight, can be painful and challenging
When does an adolescent growth spurt occur?
around age 10 (girls) and 12 (boys), and takes around 2 years
What changes do we see in an adolescent growth spurt?
- begin to see sex differences in body shape
- girls increase their fat to body ratio
- boys see an increase in muscle mass
What are secondary sex characteristics?
physical traits that indicate sexual maturation but are not directly related to fertility
ie. breast development, voice deepening, acne, and the growth of body hair
What are primary sex characteristics?
bodily changes directly related to fertility
What are primary sex characteristics in females?
menarche (first menstruation)
suggests that uterus and ovaries have grown and are now functional (ie. releasing an egg)
What are primary sex characteristics in males?
spermarche (first ejaculation)
suggests that testes, penis, and scrotum have grown and are now functional (ie. making and releasing sperm)
What is the biological influence on pubertal timing?
genetics: age at which mothers and fathers go through puberty will predict the onset of puberty in their children
What are the 3 contextual influences on pubertal timing?
- nutrition
- stress
- socio-economic status (SES)
How does nutrition affect pubertal timing in females?
ovulation and menstruation is triggered by specific level of protein called leptin found in fat
- as that protein increases, it increases the production and secretion of hormones which will then trigger the onset of puberty and the release of an egg
- fat leads to menarche
How does stress affect pubertal timing?
linked with earlier onset of puberty
ie. sexual abuse, poor family relationships, harsh parenting, family stress and conflict, parental marital conflict, high level of anxiety
How does socio-economic status (SES) affect pubertal timing?
- living within a poor family is linked with earlier onset of puberty, particularly in girls
- link between low SES and poor nutrition → overweight and obese
What is early off-timed puberty?
before 8 (girls) or 9 (boys)
What is late off-timed puberty?
after 13 (girls) or 14 (boys)
What are the effects of off-timed puberty?
linked with anxiety, depression
What type of off-timed maturation is more problematic?
early maturation linked with more problems than late maturation
What are the effects of early off-timed puberty particularly for girls?
typically, they are done with puberty by age 12
early-maturers:
- likely to feel bad about their bodies because they’re changing faster than their peers
- self-consciousness is more likely to lead to anxiety, depression, low self-esteem, negative body image, eating disorders
- more likely to be victims of rumour spreading about being sexually active, sexually harassed
What are the effects of early off-timed puberty particularly for boys?
more popular and confident
What contextual factors influence the effects of pubertal timing?
early-maturing boys and girls have a tendency to seek relationships with older peers who are more similar to them in physical maturity
- more likely to get engaged in age-inappropriate behaviour (ie. smoking, drug and alcohol use, sexual activity)
- more likely to not make good decisions, put themselves at risk
- girls have higher levels of teen parenting/abortion/birth, and STIs
How does breastfeeding benefit mothers?
- lower levels of depression
How does breastfeeding benefit infants?
- meets the infant’s complex nutritional needs
- provides with protection against infection because immunities from the mother come through the breast milk and helps to build the infant’s immune system more rapidly and earlier
- lower rates of allergies, infections, disease, asthma
- less likely to become obese
What is a safe alternative to breast milk?
formula
When do infants start eating solid foods? What do they eat?
- around age 4-6 months
- can introduce pureed foods
What happens to infant eating patterns at age 2-3?
- appetite decreases because growth is slowing down
- start learning how to feed themselves
What is the definition of food insecure?
individuals and families lack consistent access to food, resulting in reduced food intake or disruptive eating patterns (eating less, or eating lower quality foods)
Food Insecurity Statistics in Canada
- 8.3% of families report being food insecure
- Nunavut: 36.7% → highest rate of food insecurity in families
- those receiving government benefits (ie. unemployment, disability) are 3.5x more likely to be food insecure → 21.4% are food insecure
- average household earning income from unemployed → 6.1% are food insecure
- single parent families → highest rate at 22.6%
What are the consequences of food insecurity?
likely consuming less fresh fruits and vegetables, and dairy products (intake of vitamins and minerals is reduced → disruptive eating pattern)
more likely to be obese because they are not eating nutritious foods, but calorie-dense foods
kids experience developmental abnormalities, compromised immune systems, and difficulty concentration (not getting nutrient-rich foods)
What are the eating behaviours in adolescence?
- growth spurt: demands an increase in caloric intake
- diet trends: diet worsens → eat more fast food, drink more sugary drinks
What can counteract eating behaviours in adolescence?
family meals
- linked with more healthy diets, and decreased likelihood of being overweight
- especially if the meals are prepared together → preparing healthy meal is becoming part of their routine
What are the eating behaviours in adults?
- caloric intake needs to go down because they are not in a growth spurt anymore
- adults are typically less active than in adolescence, so if you are not active, you must reduce caloric intake
What is Body Mass Index (BMI)?
- standardized way of determining if someone’s weight is in a healthy range
- measure of body fat based on height and weight
What is considered obese with Body Mass Index (BMI)?
95th percentile of your weight
Overweight and Obesity Rates in Canada
2-17 year olds:
- 1978: 23%
- 2017: 30%
Overweight and Obesity Rates in USA
47%
Where are we most likely to see less overweight and obesity?
in poor, non-industrialized countries due to lack of access to resources
What are the consequences of adolescent overweight and obesity?
- 80% of obese adolescents grow up to be obese adults, difficult to reduce the weight as an adult, and it is difficult to reduce the weight as an adult
- linked with short- and long-term physical and socioemotional consequences
What are the physical consequences of adolescent overweight and obesity?
- heart disease
- high blood pressure
- asthma
- orthopedic problems (ie. hip and knee replacements because excess weight wears out the joints)
- diabetes
What are the socioemotional consequences of adolescent overweight and obesity?
- peer rejection
- depression
- low self-esteem
- body dissatisfaction
What are the causes of adolescent overweight and obesity?
- in Western, developed societies: genetics
- increase in fast food and calorie-dense nutrient-poor foods
- poor people are likely to live in neighbourhoods with no grocery stores with healthy foods → food deserts
- don’t have a safe place to play outside (low SES neighbourhoods are likely to be unsafe and less likely to have parks and playgrounds that are well-maintained)
What are the physical activity and exercise rates of childhood and adolescence in Canada?
most do not meet recommended guidelines of 60 minutes per day (33% do)
- level of physical activity decreases as they age
- 5 year olds: 74 mins/day on average
- 12-17 year olds: 48 mins/day on average
any age: boys tend to be more active than girls
- 5 year old boys: 81 mins/day on average
- 5 year old girls: 64 mins/day on average
- 12-17 year old boys: 55 mins/day on average
- 12-17 year old girls: 41 mins/day on average
How can increased rates of physical activity in childhood and adolescence be facilitated?
- parents can act as role models and engage in physical activity on a regular basis, then their kids will see that and think that it’s normal
- have access to team sport, lessons
What are causes of low physical activity in childhood and adolescence?
low SES
What is the recommended amount of physical activity for adults?
21 minutes per day
Why do adults have a lower recommended amount of physical activity?
they aren’t growing, and their bodies aren’t developing, therefore physical activity can be reduced and they can still be considered healthy
What are the physical and mental health benefits of adult physical activity?
- increases strength, balance, posture, endurance
- decreases opportunity to contract disease
- enhances immune system
- provides stress relief, protection against depression
- improves person’s mood, energy, ability to cope
Total Physical Activity
Self-reported Minutes a Day vs. Accelerometer-reported Minutes a Day
age 18-39
self-reported: 57.6
accelerometer-reported: 26.6
age 40-59
self-reported: 48.8
accelerometer-reported: 22.8
age 60-79
self-reported: 34.1
accelerometer-reported: 15.5
