MCAT Content / Biological Bases Of Behavior / Human Physiological Development

Human Physiological Development

Topic: Biological Bases Of Behavior

Human development refers to the physical, cognitive, and psychosocial development of humans throughout the lifespan.

Physical development involves growth and changes in the body and brain, the senses, motor skills, and health and wellness. Cognitive development involves learning, attention, memory, language, thinking, reasoning, and creativity. Psychosocial development involves emotions, personality, and social relationships.

During prenatal development, conception occurs and development begins. All of the major structures of the body are forming and the health of the mother is of primary concern. There are various approaches to labor, delivery, and childbirth, with potential complications of pregnancy and delivery, as well as risks and complications with newborns, but also advances in tests, technology, and medicine. The influences of nature (e.g., genetics) and nurture (e.g., nutrition and teratogens, which are environmental factors during pregnancy that can lead to birth defects) are evident. Evolutionary psychology, along with studies of twins and adoptions, help us understand the interplay of factors and the relative influences of nature and nurture on human development.

During infancy and childhood, motor development occurs. Motor skills refer to our ability to move our bodies and manipulate objects. Gross motor skills coordinate the large muscle groups that control our arms and legs and involve larger movements like balancing, running, and jumping. By the end of the second year of life, most children (except those with disabilities or other special needs) can stand up, walk/run, climb stairs, jump, and skip. As children grow older (ages 4-5), many can also catch balls, ride bikes, and run with more speed and agility. The prerequisite to all these skills is postural control—the ability to hold one’s head up, sit independently, and stand. Appropriate posture allows the child to learn to walk, run, and engage in other gross motor skills.

Fine motor skills, by contrast, involve the coordination of small muscle movements, usually involving the hands working in coordination with the eyes. Hand-eye coordination allows a child to perform such skills as drawing, using buttons and zippers, eating with utensils, and tying shoes. Children increase their mastery of these skills through practice. For example, at age 2, a child’s drawing might be a series of crayon scribbles, but by age 5, he or she might be able to draw a person’s face complete with eyes, nose, and mouth.

Children grow very quickly and meet physical milestones rapidly in the first few years of life. The following is a list of the major milestones that occur in children during those first formative years.

During puberty, an adolescent experiences a period of rapid physical growth that culminates in sexual maturity. Adolescence is a socially constructed concept. In pre-industrial society, children were considered adults when they reached physical maturity; however, today we have an extended time between childhood and adulthood known as adolescence. Adolescence is the period of development that begins at puberty and ends at emerging adulthood; the typical age range is from 12 to 18 years, and this stage of development has some predictable physical milestones.

It is this stage in life in which a child develops secondary sex characteristics. Primary sex characteristics are organs specifically needed for reproduction, like the uterus and ovaries in females and the testes in males. Secondary sex characteristics, on the other hand, are physical signs of sexual maturation that do not directly involve sex organs. In females, this includes development of breasts and widening of hips, while in males it includes development of facial hair and deepening of the voice. Both sexes experience development of pubic and underarm hair, as well as increased development of sweat glands.

The male and female gonads are activated by the surge of hormones, which puts them into a state of rapid growth and development. The testes primarily release testosterone, and the ovaries release estrogen; the production of these hormones increases gradually until sexual maturation is met. Girls experience menarche, the beginning of menstrual periods, usually around 12–13 years old, and boys experience spermarche, the first ejaculation, around 13–14 years old. Facial hair in males typically appears around age 14.

The adolescent brain also remains under development during this time. Adolescents often engage in increased risk-taking behaviors and experience heightened emotions during puberty; this may be due to the fact that the frontal lobes of their brains—which are responsible for judgment, impulse control, and planning—are still maturing until early adulthood.

 

Practice Questions

 

Khan Academy

 

MCAT Official Prep (AAMC)

Section Bank P/S Section Passage 5 Question 39


Key Points

• Human development refers to the physical, cognitive, and psychosocial development of humans throughout the lifespan.

• Prenatal development is the process that occurs during the 40 weeks prior to the birth of a child, and is heavily influenced by genetics.

• Physical development involves growth and changes in the body and brain, the senses, motor skills, and health and wellness. Cognitive development involves learning, attention, memory, language, thinking, reasoning, and creativity. Psychosocial development involves emotions, personality, and social relationships.

• Cognitive development refers to the development of a child in terms of information processing, conceptual resources, perceptual skill, and language learning.

• During infancy and childhoodmotor development occurs. Motor skills refer to our ability to move our bodies and manipulate objects. 

• Gross motor skills coordinate the large muscle groups that control our arms and legs and involve larger movements like balancing, running, and jumping.

• Fine motor skills, by contrast, involve the coordination of small muscle movements, usually involving the hands working in coordination with the eyes. 

• The brain grows and matures rapidly during early childhood, faster than any other organ in a child’s body.

• Adolescence is the period of development that begins at puberty and ends at emerging adulthood; the typical age range is from 12 to 18 years, and this stage of development has some predictable physical milestones.

• Puberty involves distinctive physiological changes in an individual’s height, weight, body composition, sex characteristics, and circulatory and respiratory systems. These changes are largely influenced by hormonal activity.

• During puberty, the adolescent develops secondary sex characteristics (such as a deeper voice in males and the development of breasts and hips in females) as their hormonal balance shifts strongly towards an adult state.


Key Terms

conception: the fertilization of an ovum by a sperm to form a zygote.

myelination: The production of a coating of myelin around an axon.

menarche: The onset of menstruation in human females; the beginning of the menstrual period.

puberty: The age at which a person is first capable of sexual reproduction.

gonad: A sex organ that produces gametes; specifically, a testicle or ovary.



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