Human Growth Patterns: Meiosis Errors and Detection

1. Title: Pattern of Human Growth 02 January 2020 Learning question: what can go wrong in meiosis and how can this be detected? Homework:Revise this module – class text next Wednesday

2. Key words • Absolute growth rate • Relative growth rate • Life cycle

3. Aims from specification (c) describe, with the aid of diagrams, the pattern of growth during the human life cycle; (d) explain and interpret growth charts for males and females from birth to 18 years of age (HSW5b); (e) distinguish between absolute and relative growth rates; (f) explain that humans are multicellular organisms in which genetically identical cells are organised into tissues, tissues into organs and organs into organ systems; (g) describe the differential growth patterns of lymphatic, reproductive and nervous tissue.

4. Growth during human life cycle • The human life cycle covers the period from conception, through: • The fetal growth phase • Growth rate is very high • Infancy and childhood • Growth rate is very rapid at first then the rate of growth slows down to a steadier rate • Adolescence • Rapid growth spurt due to puberty • Adulthood • Growth rate falls to zero, as person’s body mass or height stops increasing

5. Absolute growth rate • The graph below shows the mass of a human plotted against age. • This is the absolute growth rate of a human and us useful to show overall growth patterns • Can also be used to plot height or mass against time to show the rate of growth

6. Relative growth rate • This shows the efficiency of growth, because it compares mass or height with the measurement at the beginning of the time period • Relative growth rate is a specific growth rate. It shows the increase compared to the initial height/mass

7. Different parts, different growth rates • Humans are multicellular organisms, growing from a zygote to blastocyst, to embryo, to fetus. • Cells start off genetically identical, but differentiate to form different tissues, organs and organ systems. • Organ systems comprise several organs that work together to perform a function

9. Different parts, different growth rates • Not all organ systems develop at the same rate • The head of a fetus grows rapidly and reaches adult size early. • Humans have large brains – need to learn complex skills from an early age • Animals with smaller brains are not able to do this • Reproductive organs have a slow growth rate • Prevents humans from reproducing until they have learned the complex skills they need to look after a very dependant baby

11. Different parts, different growth rates • Describe the growth rate of the nervous system compared to the average of all systems and the reproductive system • Can you think of a reason to account for the growth pattern of the lymphatic system?

12. Different parts, different growth rates • The lymphatic system is involved in the immune system. • A fetus gets its immunity from antibodies passed from the mother via the placenta (passive immunity) • After birth, the baby continues to receive antibodies via breast milk • The lymphatic system develops very rapidly in childhood and the immune system is very active in producing antibodies to common childhood pathogens (active immunity) • Reproductive system is last to develop, as these organs are not needed until puberty. • This occurs between 9-15 years in girls and 10-16 years in boys

13. Complete questions on page 93