Answers to Revise Questions

At what stage of prenatal development is the embryo most susceptible to damage? Name one substance recommended to minimise such damage.


  • The first 8 weeks of the pregnancy.
  • Folic acid.

What is apoptosis and why is it important in development?

Ans: Apoptosis is programmed cell death. It is a major process in development as it removes tissues and cells no longer required and permits remodelling of the developing body.

What do you understand by embryogenesis and what are the major structures created?

Ans: The first 8 weeks of pregnancy is embryogenesis during which the basic structure of the body is laid down. The early part of development is formation of two sets of structures: the three germ layers of cells which form the embryo; and the support tissues which form the placenta, umbilical cord and the amniotic sac which surrounds it. By the end of this stage the external features and most organs of the embryo can be identified.

What are the functions of the placenta?

Ans: During the pregnancy the foetus obtains nutrients and oxygen from the maternal circulation through the placenta and waste products are eliminated from the foetus through the placenta into the maternal circulation for excretion. The placenta also acts as an endocrine organ.

Briefly describe the cardiovascular changes which occur in the transition from intrauterine to independent life.

Ans: The hole in the septum (foramen ovale) between the two sides of heart becomes closed and the ductus arteriosus also closes shortly after birth. This enables the normal separation between the two parts of the circulation and adequate blood to flow from the heart to the lungs and return, and to the body and return.

Which tissues grow most rapidly in the first few years of life?

Ans: The brain and head.

What do you understand by the terms puberty and adolescence?

Ans: Adolescence begins with the onset of puberty and ends with the acceptance of adult identity and behaviour. Puberty is the period from the beginning of the endocrine changes leading to development of the sexual characteristics to the time when the child has become an adult with reproductive capacity.

What are the three stages of adulthood and of ageing?

Ans: Early adulthood: about 20 to 40 years.

Middle adulthood: about 40 to 65 years.

Late adulthood: about 65 until death:

young-old, 65–74 years;

middle-old, 75–84 years;

oldest-old, ≥85 years.

Outline the changes in the reproductive systems of men and women that occur as they get older.

Ans: Women pass through the menopause (menstruation ends) usually somewhere between 45 and 55 years. Before that time fertility has begun to decline and hormone levels fall. A number of symptoms may occur for a period of some 2 to 5 years and these can include reduced sex drive; vaginal dryness and itching, and pain or discomfort during sex; hot flushes; problems with sleeping, sometimes associated with night sweats; urinary tract infections; changes in mood and tiredness, sometimes depression and/or anxiety; headaches; palpitations. Men do not lose fertility outright although sperm levels may fall and testosterone secretion declines.

Outline the physiological changes which commonly occur as someone is dying.

Ans: Diminished function in all systems of the body usually occurs in dying. Signs and symptoms can occur: fatigue and weakness; reduced blood flow through the skin which increases the risk of pressure sores (decubitus ulcers); loss of appetite and reduced fluid intake leading to dehydration; cardiac failure/dysfunction; renal failure; nervous system dysfunction. Most people gradually lose consciousness, become comatose, and die peacefully as breathing ceases and the heart stops beating.