Life Cycle

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  • Senior Citizens
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Life Cycle

This section compiles information based on stages of life cycle of Users i.e specific content for Kids and Senior Citizens. Keep visiting this space for more such content specifically classified for Teens and Youth.

Making a Human


In the womb


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Your life began as a single cell, no bigger than a pinprick, inside your mother’s body. Over time, that sell grew and developed into your Complex body containing trillions of cells. Our bodies changed and develop over the course of a lifetime. From birth to old age we go through several distinct stages of life. During infancy and continuing through childhood, we grow rapidly and pick up life skills. In our teenage years we mature into adults as grown women and men we may have children of our own. Finally in old is our bodies star to wear out.

Human Life Cycle mainly consists of 6 stages. They are simply; foetus, baby, child, adolescent, adult and old person. Let’s talk about each of these stages in detail.

Stages of Human Life Cycle:

Stage 1

Foetus in the womb

An egg from the mother is fertilised by a sperm from the father and turns into an embryo inside the mother’s womb. At first this creation looks like a bundle of cells. By about eight weeks this bundle of cells gradually turns into the shape of the human body. This is called the foetus. The foetus totally depends on its mother as it cannot breathe, drink or eat by itself.

Example of a foetus in the womb

Stage 2


After nine months in the mother’s womb, the baby is born. Babies from birth to 1 year are also known as infants. Newborn babies can breathe, suck, swallow and cry when they feel hungry, cold and hot temperatures or any uncomfortable situation. This is how they communicate as they still cannot talk. Babies are usually fed on mother’s milk.

A baby birth – 1 year

Stage 3


The baby grows into a child. It slowly learns to crawl and then walk, talk, run, jump, eat by itself, identify things in its surroundings, communicate properly, read and write, make friends and do many more childhood activities. In the stage childhood, children can be divided into; toddlers (1-3 years), preschoolers (3-5 years) and primary school children (5-12 years).

A Toddler 1 – 3 years

A Preschooler 3 – 5 years

A Primary School Boy 5 – 12 years

Stage 4


At the stage, adolescence, the child grows into an adolescent through a period called Puberty. Puberty usually takes place in the child’s teenage years, starting from 13 years up to 19 years of age. Therefore, adolescents are also called teenagers. During the puberty a rapid growth and changes of the body take place. These include changes of the body shape, growing hair on some parts of the body, for example, boys grow hair on their faces, and also, boys’ voice becomes deepen and rough. Similarly, at this stage the behaviour patterns and attitudes of the teenagers will change as they are independent in doing their day-to-day activities.

A Teenage Boy 13 – 19 years

Stage 5


People who are from age 20 years to 65 years old are called adults. Adults can reproduce, make their own families and so continue the life cycle. Adults can be divided into; young adults (20 – 36 years)middle-aged adults (36 – 55 years) and older adults (55 – 65 years).

A Middle-aged Adult 36 – 55 years

Stage 6

Old Person

When a person reaches 65 years of age, he is known as an old or elderly person. The average life expectancy of a person can vary from 70 to 85 years. But it totally depends on the health of each person, as some die before 70 years, whereas some die after 85 years. However, the human life cycle ends at this stage.

An Old Person 65+ years


  1. Identify and define the different stages of the human life cycle.
  2. Explain how the human body develops from infancy through the toddler years.

According to the American Journal of Clinical Nutrition, the human life span, or the maximum length of time possible for human life, is 130 years.Ordovas, J. M. “Living Well to 100: Nutrition, Genetics, Inflammation.” Am J Clin Nutr 83 (2006): 401S490S. Human bodies change significantly over time, and food is the fuel for those changes. People of all ages need the same basic nutrients—essential amino acids, carbohydrates, essential fatty acids, and twenty-eight vitamins and minerals—to sustain life and health. However, the amounts of nutrients needed differ. Throughout the human life cycle, the body constantly changes and goes through different periods known as stages. The major stages of the human life cycle are defined as follows:

  • Pregnancy. The development of a zygote into an embryo and then into a fetus in preparation for childbirth.
  • Infancy. The earliest part of childhood. It is the period from birth through age one.
  • Toddler years. Occur during ages two and three and are the end of early childhood.
  • Childhood. Takes place from ages four to eight.
  • Puberty. The period from ages nine to thirteen, which is the beginning of adolescence.
  • Older adolescence. The stage that takes place between ages fourteen and eighteen.
  • Adulthood. The period from adolescence to the end of life and begins at age nineteen.
  • Middle age. The period of adulthood that stretches from age thirty-one to fifty.
  • Senior years, or old age. Extend from age fifty-one until the end of life.

Changes during Pregnancy


 The human life cycle from the prenatal period into early childhood. We begin with pregnancy, a developmental marathon that lasts about forty weeks. It begins with the first trimester (weeks one to week twelve), extends into the second trimester (weeks thirteen to week twenty-seven), and ends with the third trimester (week twenty-eight to birth). At conception, a sperm cell fertilizes an egg cell, creating a zygote. The zygote rapidly divides into multiple cells to become an embryo and implants itself in the uterine wall, where it develops into a fetus. Some of the major changes that occur include the branching of nerve cells to form primitive neural pathways at eight weeks. At the twenty-week mark, physicians typically perform an ultrasound to acquire information about the fetus and check for abnormalities. By this time, it is possible to know the sex of the baby. At twenty-eight weeks, the unborn baby begins to add body fat in preparation for life outside of the womb.Elaine U. Polan, RNC, MS and Daphne R. Taylor, RN, MS, Journey Across the Life Span: Human Development and Health Promotion (Philadelphia: F.A. Davis Company, 2003), 81–82. Throughout this entire process, a pregnant woman’s nutritional choices affect not only fetal development, but also her own health and the future health of her newborn.

Changes during Infancy


A number of major physiological changes occur during infancy. The trunk of the body grows faster than the arms and legs, while the head becomes less prominent in comparison to the limbs. Organs and organ systems grow at a rapid rate. Also during this period, countless new synapses form to link brain neurons. Two soft spots on the baby’s skull, known as fontanels, allow the skull to accommodate rapid brain growth. The posterior fontanel closes first, by the age of eight weeks. The anterior fontanel closes about a year later, at eighteen months on average. Developmental milestones include sitting up without support, learning to walk, teething, and vocalizing among many, many others. All of these changes require adequate nutrition to ensure development at the appropriate rate.Beverly McMillan, Illustrated Atlas of the Human Body (Sydney, Australia: Weldon Owen, 2008), 248.

Changes during the Toddler Years


Major physiological changes continue into the toddler years. Unlike in infancy, the limbs grow much faster than the trunk, which gives the body a more proportionate appearance. By the end of the third year, a toddler is taller and more slender than an infant, with a more erect posture. As the child grows, bone density increases and bone tissue gradually replaces cartilage. This process known as ossification is not completed until puberty.Elaine U. Polan, RNC, MS and Daphne R. Taylor, RN, MS, Journey Across the Life Span: Human Development and Health Promotion (Philadelphia: F.A. Davis Company, 2003), 108. Developmental milestones include running, drawing, toilet training, and self-feeding. How a toddler acts, speaks, learns, and eats offers important clues about their development.

Nutrition and Early Development


 During pregnancy, infancy, and the toddler years, and how nutritional choices affect those changes. From pregnancy through the toddler years, children are entirely dependent on parents or caregivers for nutrients. Parents also help to establish a child’s eating habits and attitudes toward food. So, adults must be mindful of the choices they make and how those choices influence a young child’s development, health, and overall well-being.



  • The human body constantly develops and changes throughout the human life cycle, and food provides the fuel for those changes.
  • The major stages of the human life cycle include pregnancy, infancy, the toddler years, childhood, puberty, older adolescence, adulthood, middle age, and the senior years.
  • Proper nutrition and exercise ensure health and wellness at each stage of the human life cycle.
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