Main content
MCAT
Course: MCAT > Unit 11
Lesson 2: Human development- Human physiological development
- Egg, sperm, and fertilization
- Early embryogenesis - Cleavage, blastulation, gastrulation, and neurulation
- Implantation
- Germ layer derivatives
- Gestation
- Major motor milestones
- Motor development
- Neonatal reflexes
- Physical development in adolescence
- Brain changes during adolescence
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Physical development in adolescence
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Video transcript
- [Instructor] When we
talk about adolescence, we're talking about a
transition period that exists between childhood and adulthood. But what does that actually mean? Honestly, it means different
things for different cultures. So, cultures where children
leave school after a few years, and then go and find a job
and are self-sufficient by the time that they're teenagers, they don't really have
this adolescent period. Even within Western cultures,
the idea of adolescence is sort of a new one. Historically, children,
and definitely teenagers, were basically treated
as kind of mini adults, or just adults themselves. I think that you could
definitely have a long debate, and I could definitely make a whole video, about whether or not adolescence
is a social construct. But for today, in the U.S.
and most of the Western world, we would say that adolescence
starts at the beginning of sexual maturity and ends
with independent adult status. So that would mean living
apart from your family and having your own interests,
your own job, et cetera. Mostly, it's about being self-supported. And when we talk about adolescence, we typically say that
it begins with puberty. It's about a two year long
period of sexual maturation, during which time a person
becomes capable of reproduction. It starts at different
times in males and females. For males, it typically
starts around age 13. For females, it starts around age 11. And again, that's just
when it generally starts. It could start earlier or
later, depending on the person. And although puberty
is actually a process, we usually associate it with
two very specific incidents that occur during this
time, two landmarks. For males, that event is
their first ejaculation, which usually occurs as
a nocturnal emission. For females, it's their
first menstrual cycle, or their first period. Just like puberty starts
at different times for males and females, these
milestones are also reached at different times, usually
around age 14 for boys, and somewhere between
12 and 13 for females. And this, as well as the
earlier start time in general, is why girls tend to be taller than boys between the ages of 11 and 14. But then, once boys catch
up in terms of puberty, they have a growth spurt and
typically wind up being taller. Aside from these milestones,
puberty is also associated with many physical changes. These include two main things. The first is primary sex characteristics. This basically describes the development of our reproductive organs,
or the parts of our body that are actually used for reproduction. So this would include the testes in males and the ovaries in females, and just overall genital
development in both groups. And we say that they're
primary sex characteristics because these are the things that make sexual reproduction possible, which is, after all, what
puberty is all about. Puberty also brings about the development of secondary sex characteristics. These are nonreproductive
sex characteristics. Meaning that even though they are related to sexual development,
they are not required for sexual reproduction. And for males, this would include things like a change in voice,
and a growth of body hair, and also a growth spurt. For females, this includes the development of breasts and hips. For both genders, puberty
tends to bring about the development of both
underarm hair and pubic hair. There are a couple of things
that we need to keep in mind. First, is that the sequence
of physical changes is typically the same in all individuals. However, the timing is not. Some females enter puberty
as early as age nine or as late as age 16. It depends on a ton of different things: their height, their
weight, their nutrition. And usually, an earlier
period or a late period isn't actually a sign that anything is wrong. It's just a sign of
individual differences. However, there are
different social effects that are associated with early puberty. Boys that go through puberty
early, who mature faster, tend to be stronger and taller,
and therefore more athletic, and with that comes a
number of social things. They tend to be popular and
self-assured and independent. And, while I'm sure that we will all agree that it's nice to be popular,
it's nice to be liked, but there are also some negative things that are associated with
early puberty in males, things like increased
tendency for delinquency, and increased alcohol use. For females, the story
isn't really so clear. In fact, there aren't really any positives for going into puberty early. These girls aren't typically more popular. In fact, they're typically
the focus of a lot of teasing and sometimes even sexual harassment. They tend to be out of
sync with their friends in terms of their interests. And while a lot of it
depends on the attention that they get and the
interactions that they have, and the responses that
they get from both adults and their peers, early
physical maturation in females doesn't really go along with
any positive social factors.