.. spurt. Next their first menstruation occurs. By this time, they have achieved adult stature. By fourteen, girls breast growth is completed and at fourteen and a half, their pubic hair growth is completed. Boys major puberty changes occur a little later than girls.
First, their testes begin to enlarge at the age of eleven and a half. Pubic hair appears and the penis begins to enlarge at twelve, and then the height spurt begins. Their spermarche occurs at thirteen. At the age of fourteen, they reach the peak of their height spurt, their facial hair begins to grow, and their voice begins to get deeper. After this, the growth of their penis is complete.
Then, at fifteen their pubic hair growth is complete and the peak of their strength spurt has occurred. Finally, after all of these changes, adult stature is reached. The most noticeable part of male puberty seems to be the voice as it cracks a lot and the facial hair. For me the most noticeable part of my puberty was the growth of my chest and the arrival of my menstrual cycle. My face seemed to become oilier during this time as well. This was not a fun part of growing up.
Once again, as with all the stages of physical development, nutrition and heredity have an impact on puberty, but they mainly only deal with the timing. This age gap is characteristic of the rep lacement of baby teeth with permanent ones. Writing becomes more legible during this time as well. Organized games with rules begin to become more and more common at this time as well. Puberty is the most distinguishable part of human physical development.
After puberty, it seems like there are no more major physical changes that occur. I do not really feel like I have changed that much since I was sixteen. I weigh more, and I seem to be less flexible, but those are both things relative to daily activity. Early adulthood is the next part of human physical development. Throughout the twenties and thirties, early adulthood development occurs. During this time, physical changes and the declines in the functioning of the body are so gradual that one can hardly even notice them.
When an adult reaches the age thirty, vision starts to decline because the lens stiffens and thickens, and they can no longer see things up close as well. Some of the organs begin to decrease in function as well. When exercising, the respiratory volume decreases and the breathing rate increases with age. The amount of air that can be forced in and out of the lungs decreases up to fifty percent from the age of twenty to the age of fifty. For reasons such as this, athletic performance peaks from the twenties to thirties and then begins to decrease.
The research the have done on incredible athletes show us that the upper biological limit of motor capacity is reached by the first part of early adulthood. The declines in heart and lungpower usually show up only during exercise. From the ages of twenty to thirty, the elasticity of the skin begins and continues, and weight gains begin and continue through middle adulthood. Sexual activity increases during this time as well. Aging is more extreme for those who lead less active lives.
Also, the reproductive capacity tends to decline with age. For women it begins to decline especially after the age of thirty five, and for men it starts to decline after the age of forty. From thirty to forty years of age, vision declines along with hearing and the skeletal system. Women begin to experience problems with fertility, the hair begins to turn gray and thin out, and sexual activity decreases. Middle adulthood is the next age group where significant changes occur physically in human beings. It is merely a continuation of the changes that begin in early adulthood.
This is the time when vision and hearing really decline a noticeable amount. Humans in this age group lose ability to see as well in dim light, and seem to always need a pair of bifocals. Hearing aids seem to start appearing a little bit at this time in some people as well. Mens hearing declines much faster than womens. I notice more old men that cant hear than I do old women. The epidermis becomes not as firm and results in wrinkling of the skin.
Skin spots become prevalent around the age of fifty. Crows feet are among the first major wrinkles to appear. Massive sun exposure earlier in life tends to make the skins wrinkling a faster process, and smoking seems to have a similar effect as well. Muscle mass start to decline a lot in the forties as well, and at the same time, fat is put on at a more rapid rate. Around this time, women begin to experience menopause, which is the end to the reproductive capacity. There is no male counterpart for menopause, but men do experience some decline in their sperm count and semen.
The mineral capacity in the bones begins to decline, even though the bones are broadening. The loss of bone mass and bone strength causes height to decrease in some people. From the ages of fifty to sixty, the human eye no longer has its accommodative ability at all. Hearing loss at this time extends to all frequencies. It remains only for the highest tones.
Skin of course, keeps on getting wrinkles and age spots are more common. Menopause is the major reproductive change that women undergo during this time. Height drops because of lower bone mass, which continues to decline. Late adulthood seems to be the time when everything declines physically. When I think about old people, the two words that come to my mind are wrinkles and saggy. From the ages of sixty to eighty, many things are deteriorating physically. Neurons begin dying at rapid rates.
Vision continues to decline, and people at this age have a harder time distinguishing colors. Also, depth perception and sensitivity to glare worsen. This age is the hearing aid age. Hearing continues to decline throughout the frequency range. Sometimes sense of smell lessens as well.
Loss of touch in fingertips is common. The stress during exercise becomes greater because of the continued decline in respiratory and lung functions. Risk of illness is much greater in this late stage of life because the aged immune system. This age group also tends to experience some difficulty in going to sleep at night; this occurs in men more so than women. Hair obviously continues to thin and gray and wrinkles become much worse and skin sags and is thinner. Because of the fact that the body is losing lean muscle mass during this time, height and weight continue to lessen.
This leads to increased risk of osteoporosis. Sex becomes not as intense. It seems like every part of the human body lessons or worsens after a person reaches late adulthood. Once a human reaches eighty or older, everything described previously just continues and gets worse. Mobility, however, goes away, and it gets harder to get around. This is because of the diminishing muscle and bone strength.
Wheel chairs and walkers and canes are used as an aid in movement when mobility no longer exists. Death comes after or even during this stage. There are three ways that death occurs generally. The first way is the agonal phase. During this phase, gasps and muscle spasms happen when the body can no longer sustain life.
The second phase is clinical death. This is when a short interval follows in which heartbeat, circulation, breathing, and the brain functions all stop. Resuscitation is still available at this stage. In the third stage of death, mortality, the person actually passes into permanent death. Soon afterward, this dead person becomes shriveled looking, and has thus undergone all of the physical development a person goes through in a lifetime.
Physical development is the only type of development that one can actually witness. Ever person generally goes through some form of the same development through each age group. The human body is very unique and all of these changes that we experience are what makes us so interesting.