Growth and Development An Introduction

Stages of the Human Lifespan Each stage of the human lifespan is associated with an approximate age and certain developmental milestones. Prenatal (conception – 9 months). There are 3 sub-stages occurring during this period Germinal stage (week 3 – middle of week 4) Embryonic stage (middle of week 4 – week 10) Foetal stage (week 11 – birth)

Stages of the human lifespan Infancy & toddlerhood (birth – 3 years) Infancy (birth – 18 months) Toddlerhood ( 18 months – 3 years) Childhood (3 years – 12 years) Early childhood (3 – 6 years) Late childhood (6 –12 years)

Defining Growth Growth – an increase in the size and number of cells in the body. - is quantitative ie: it can be measured. - involves change in weight, height, specialized cells that make up body systems etc

How does growth occur? Growth involves production and replacement of cells, as well as an increase in cell size. New cells are formed by a cell division process known as mitosis. Cells are able to perform different functions as they differentiate this creates cells with specialized characteristics eg: bone cells, nerve cells.

Body Systems & Structures Each system is made up of various types of tissues designed to carry out a specific function. Skeletal System – supportive structure of body , bones linked by joints to enable movement. Circulatory System – moves blood & it’s contents throughout the body. Consists of heart & blood vessels – these range in size from tiny capillaries to veins & much larger arteries.

Body Systems & Structures cont… Muscular System- muscles are attached to skeleton by various types of connective tissue. Muscles enable movement. Respiratory System- works with the circulatory system, the lungs restore O2 to blood to enable it to be transported to all body cells. Endocrine System – produces & releases hormones that act on various parts of the body. It consists of a series of glands that release hormones at receptor sites.

Body Systems & Structures cont….. Nervous System – transports neural impulses (messages) around the body. Nerve cells are arranged to form 2 main parts of the nervous system. The 1st is CNS (central nervous system) = brain & spinal cord, and the 2nd is PNS (peripheral nervous system) = connects rest of the body to the CNS.

Body Systems & Structures cont… Digestive System – responsible for the breakdown of food into elements that can be used by cells in the body. Food passes through the mouth, oesophagus, stomach & intestine. Other organs assist in the breakdown & absorption eg: liver, pancreas

Body Systems & Structures cont…. Reproductive System – production and storage of gametes (sperm & ova) to enable fertilization to occur.

When does growth occur? Obviously not all growth occurs at once. There are 4 important periods of growth during the human lifespan Most rapid – between conception and 1st birthday ie: from 2 cells to fully functioning infant with countless differentiated cells. Slow & steady growth from approx 12 months to puberty.

Periods of Growth cont… 3. Adolescent growth spurt is rapid and lasts for about 2 yrs. Timing is different for boys (12 – 13yrs) and girls (11 – 12yrs). It is important to recognize that individual variation with timing of growth is normal. 4. After growth spurt of puberty, growth slows down again. An individual reaches maximum height and physical development consolidates.

What happens after a person’ height is reached in early adulthood? Growth continues as cells are constantly dying and need to be replaced. Repair & replacement continues, but as we age this process slows down. Eventually the body declines as replacement rate diminishes.

Interrelationship between growth & development It is useful to understand that the terms growth and development are often used interchangeably, this is not correct. It could be said that in order to grow we need to develop, and that if we are to develop we need to grow eg: to be able to walk, the nervous system must have developed sufficiently. At the same time, leg muscles & skeleton must have grown to appropriate size & strength to support weight of upper body when activity is performed. We continue to grow & develop from conception to death.

What is development? Development is the gradual changes that occur in our physical, social, emotional & intellectual states & abilities. Development is lifelong. Development is qualitative – the quality improves or becomes more complex, eg: Intellectual development involves changes in a person’s perceptions & thinking; we can’t actually “see” this. It is not easily measured.

Physical development

Physical Development Changes that relate to our size & shape and therefore our body structure. Motor development is a type of physical development – in order to move, we use our motor skills. (the word “motor” refers to movement). As we grow & develop we gain greater control over muscles & joints in our body enabling a huge range of movements. Gross motor skills – ability to control movement of larger muscle groups ie: leg & arm muscles for activities such as jumping, running, etc. Fine motor skills – ability to control movement of smaller muscle groups. Precise movements such as writing, drawing, playing a musical instrument, turn the pages of a book, etc

Social Development Social development is concerned with changes in the way we interact with those around us as we move through the life span. We become socialised – the process of acquiring values, attitudes & behaviours through interacting with others. The ways that we interact change slowly over time ie; think about the way young people communicate with each other in early primary school compared to the way they do in secondary school.

Emotional Development Emotional development deals with our feelings & moods and the ways which we express, understand and control them. As a very young child we only know how to express such basic emotions as happiness & sadness. Over time the range of emotions we identify and express increases.

Intellectual Development Intellectual development (also known as cognitive development) refers to the ways in which we are able to think & reason. As young children we understand the world in “concrete” terms (things that we can see & feel). As we get older we are able to understand things without actually having to see them – they are referred to as “abstract” concepts. eg: young children need blocks or counters to be able to add numbers, but by the time they are in secondary school they can deal with more abstract concepts such as algebra I in maths and forming hypotheses in science.

Summary of types of development Physical development Changes in our Size Shape Overall body structure Social development Changes in our ability to interact with Family Friends Authority figures, etc Emotional development feelings & moods How and when these are expressed Intellectual development Ways of thinking Ability to solve problems Reasoning abilities

Principles of Development There are a number of principles or “rules” that apply to our understanding of how development occurs in humans. Development requires change. Obviously development involves change. The major changes that occur over the lifespan are: Changes in physical size, such as height & weight Changes in body proportions ie: an infant’s head makes up a larger proportion of the overall body mass than an adult’s Changes to features. Some appear, some disappear eg: types of speech & language used, baby teeth

Principles of Development cont... 2. Early development is essential for late development. What occurs during the early stages of our development sets the foundation for all future development, The earliest development begins at conception. Cells divide & differentiate in order to form certain body structures to perform vital functions eg: brain. The first 3 months are referred to as the “critical period” and are the most important. During these weeks, if anything interferes with this formation, problems can occur with development, both now & in the future eg: consumption of alcohol can affect brain development, leading to learning & behavioural problems during childhood.

Principles of Development cont…. 3. Development equals maturation plus learning. Maturation – process whereby a person gradually realises their genetic potential. It is commonly used to describe development because it has a lot to do with the way we function. Learning involves relatively permanent acquisition (or modification) of certain behaviours, usually through interaction with the environment. We are born with a set of behaviours that are reflexes 9not learned). They help us to adapt to our new environment outside the uterus eg:sucking reflex. Most behaviours from this point on are learned. Maturation influences the ability to learn ie: if we are not mature enough to learn, then we are not ready to learn.

Principles of Development cont…. 4. The general pattern of development is predictable.

Principles of Development cont….

Principles of Development Development through the lifespan is predictable. We all experience the same general pattern of development. There are 2 laws that indicate the directions of development that humans follow: Cephalocaudal law – development occurs from top of body, down to the bottom ie: from head to toes eg: an infant learning to crawl must first be able to raise head & upper body, using neck first, then arms. Very little leg movement initially. Gradually control will be gained over leg muscles and eventually the infant will be able to coordinate these muscles so that crawling is possible.

Principles of Development 2. Proximodistal Law – development takes place from the centre (inside) of the body and extends outward to the body’s periphery eg: crawling (again) – musvle development is at first in the trunk of the body – these muscle are important for breathing, digestive processes, etc. Once these muscles are developed, legs & arms follow. Another aspect of the predictable nature of development is evident during the adolescent growth spurt. At puberty most adolescents experience a rapid increase in height & weight (growth) as well as other changes.

Principles of Development Percentile charts – over many years data has been collected about height & weight from birth to adulthood. This data has been compiled into what is referred to as “norms” (or normal range). A percentile chart is a graph representing these “norms” for growth in height & weight for a given population. On these charts a series of lines allows the individual to be compared o “normal” development statistically. Most people progress at around the 50th percentile ie: approx 50% of people are this height/weight (the average). The other lines indicate whether an individual is above or below what is considered to be average.

Principles of Development Percentile Charts

Principles of Development 5. There are individual differences in development. Although we all follow a general pattern, there is also individual variation. Differences relate to rate & timing of development eg: a commonly asked question is “When did your child start to walk?” Genetic influences are mainly responsible for these variations, but environmental factors also need to be considered eg; prolonged illness.

Summary of The Principles of Development Development requires change Physical size Body proportions Some features appear & others disappear Early development is essential for later development Later development is based on foundations that have been established & consolidated during early development Development equals maturation plus learning Maturation – gradually realising genetic potential Learning – relatively permanent acquisition (& modification) of behaviours The general pattern of development is predictable Cephalocaudal Law Proximodistsl Law There are individual differences in develoment Rate timing