Week 1

Question 1

How is development different than growth?

Answer 1

Growth: quantitative increase in size
Development: Progression from an immature to a mature state measured by functional capacity regardless of size

Question 2

Define growth trajectory

Answer 2

The timing and speed of growth and maturation as they pertain to a “typical” growth of a human

Question 3

After birth, body growth (increases/slows) compared to intrauterine growth

Answer 3

Slows

Question 4

After birth, brain growth (slows/accelerates) compared to intrauterine growth

Answer 4

Accelerates

Question 5

During infancy, most or all nutrition is provided via…

Answer 5

Lactation

Question 6

Coinciding with weaning, this physical structure appears in infants

Answer 6

Deciduous dentition

Question 7

Describe the digestive system of an infant

Answer 7

Immature – teeth and organs are not well developed, infants require liquid/soft nutrient-dense foods provided by adults

Question 8

What parts of the body are growing significantly during childhood?

Answer 8

Brain - everything else is growing slowly

Question 9

First permanent teeth erupt during this life stage

Answer 9

Childhood

Question 10

Humans are vulnerable to predation and disease during this life stage

Answer 10

Childhood

Question 11

On average, brain growth in weight ceases at this age

Answer 11

7 years

Question 12

What are the “bookend” events of childhood?

Answer 12

Weaning until ~ age 7

Question 13

What are the “bookend” events of the juvenile stage?

Answer 13

~7 years until the onset of puberty

Question 14

Define the growth rate of the body, generally during the juvenile stage

Answer 14

Overall relatively slow growth rate

Question 15

If not a lot of significant growth is happening during the juvenile stage, what is the importance of this stage?

Answer 15

Important time for LEARNING economic and social skills. At this point, juveniles can start learning to assist with food production and infant care

Question 16

What important hormonal-brain axis is turned on at the onset of puberty?

Answer 16

The HPG axis

Question 17

What are the 2 most important hormones involved in the onset of puberty?

Answer 17

Estradiol and Testosterone

Question 18

Estradiol is produced in (1) from (2)

Answer 18

1. Ovaries
2. Aromatization of testosterone

Question 19

In the hypothalamus, when the HPG axis is turned on, the hypothalamus secretes…

Answer 19

GnRH (Gonadotropin-releasing hormone)

Question 20

Which anterior pituitary hormones are secreted in response to GnRH secretion by the hypothalamus?

Answer 20

FSH and LH

Question 21

Both sexes require estradiol and testosterone, but undergo different sexual development due to a difference in…

Answer 21

The relative amounts of hormone present

Question 22

Testosterone can be produced by these 3 organs/glands

Answer 22

Testes, ovaries, adrenal glands

Question 23

Puberty is initiated by…

Answer 23

The return of GnRH pulsatility after a period of axis dormancy

Question 24

True or false: once re-activated at the onset of puberty, GnRH secretion is constant

Answer 24

False: pulsatile release

Question 25

How many neurons in the hypothalamus secrete GnRH?

Answer 25

approx. 2000

Question 26

To initiate puberty, GnRH pulses need to occur once every...

Answer 26

90 minutes

Question 27

During puberty, LH increases (1)-fold and FSH increases (2)-fold

Answer 27

1. 25x 2. 2.5x

Question 28

What happens during puberty and how it happens (e.g. development of secondary sex characteristics) is determined by...

Answer 28

The frequency of GnRH pulses

Question 29

Which sex hormone is important for the linear growth during puberty?

Answer 29

Testosterone

Question 30

What are the "bookend" events of Adolescence?

Answer 30

Onset of puberty, ends 5-8 years after the onset of puberty

Question 31

During adolesence, growth accelerates in this way

Answer 31

Increase in height and weight

Question 32

Peak height velocity (PHV) is reached around this time after GnRH pulsatility resumes

Answer 32

~3 years

Question 33

What are the average age ranges for adolescence in males and females?

Answer 33

F: 10-18 M: 12-21

Question 34

How does estradiol act on the skeleton? How does this explain why the average female is shorter than the average male?

Answer 34

Estradiol contributes to closing of growth plates, this means female growth plates close sooner, therefore male growth can occur for longer

Question 35

Adolescence continues until an individual stops...

Answer 35

Growing

Question 36

Research on puberty uses a common marker, which is...

Answer 36

Age of max growth rate/peak height velocity

Question 37

Cessation of growth in height and weight is usually accompanied by the appearance of (2)

Answer 37

1. 3rd Molars 2. Secondary sex characteristics

Question 38

What are the "bookend" events of adulthood?

Answer 38

Completion of skeletal growth until the end of reproductive capability

Question 39

Since growth is not occurring during adulthood, energy is funnelled towards

Answer 39

Body maintenance and reproduction

Question 40

Which life stages are unique to humans compared to other primates?

Answer 40

Childhood, Adolescence, Post-reproduction

Question 41

What is special about the growth rate achieved by humans during puberty?

Answer 41

It is incredibly fast, faster than the peak growth rate of any other *mammal*

Question 42

Humans have a unique reproductive "schedule" in 3 ways: name these

Answer 42

1. reach reproductive maturity very late 2. once we reach reproductive maturity, there tends to be a significant lag between the first birth 3. breastfeeding stops very early

Question 43

What is special about the human inter-birth interval?

Answer 43

It is very short

Question 44

What is special about human longevity?

Answer 44

Unprecedented longevity compared to other primates

Question 45

How is the cessation of breastfeeding related to the inter-birth interval of humans?

Answer 45

Breastfeeding suppresses ovulation, it is energetically expensive to breastfeed and ovulate at the same time, by weaning earlier we can start ovulating sooner after birth

Question 46

Why do humans most likely have childhood and adolescence?

Answer 46

Childhood: Weaning sooner = entry into childhood, shorten the interbirth interval, therefore increase mother's fitness Adolescence: Adolescents can help take care of young!

Question 47

Why do humans have a long post-reproductive period?

Answer 47

Grandmother hypothesis: a post-reproductive parent can increase the fitness of their genes indirectly by helping the survival of her offspring which have her genes

Question 48

Why do humans grow so slowly?

Answer 48

Because it takes us so long to grow our energetically expensive brains

Question 49

Why do humans go through puberty?

Answer 49

It is essentially a catch-up time where our bodies have to catch up to our brains, which have grown significantly in size

Question 50

The timing of the onset of puberty may be different due to...

Answer 50

Different body fat stores and nutritional status

Question 51

Puberty likely evolved in a "flexibly timed" way so that...

Answer 51

The body may enter puberty when nutritional stores are optimal