Birth and Post-natal Development

1. Birth and Post-natal Development Unit 2 The Continuation of Life Mrs Smith Ch18 Birth & Post-natal development

2. Higher Human Biology Unit 2: The continuation of life Chapter 18: Birth and Post-natal Development Mrs Smith Ch18 Birth & Post-natal development

3. What you need to know: The arrangements. Birth • The role of oxytocin at birth and the use of artificial hormones in induction of birth. • Nutrition of the new-born (Consideration of the nutrition of the new-born should include the presence of antibodies in colostrum and breast milk and some reference to the possibility of chemical contamination of colostrum and breast milk). The pattern of growth after birth • The major stages of the growth curve, including changes in body proportions. • The role of growth hormone (The general effects of growth hormone on the growth process should be considered, but microscopic details of bone structure or bone growth are not required). • The major body changes in males and females at puberty. • Hormonal changes and development in males and females at puberty. Mrs Smith Ch18 Birth & Post-natal development

4. Learning Intentions Success Criteria Understanding how the embryo develops inside the uterus and effects that the uterine environment can have on this development • Explain the role of oxytocin at birth and the use of artificial hormones in induction of birth • Describe how the new born infant is nourished • To find out about the composition of colostrum Mrs Smith Ch18 Birth & Post-natal development

5. Image source: images.doctorberlin.com Birth • A human pregnancy lasts for about 38 weeks. • After the full period of gestation when the foetus is described as ‘full term’. Gentle contractions of the uterus move the foetus into the birthing position, with the head close to the cervix (PATURITION). Mrs Smith Ch18 Birth & Post-natal development

6. Anterior (front) lobe Labour Labour is brought on by the hormone oxytocin, which is secreted by the mother’s posterior pituitary gland. This hormone stimulates involuntary rhythmic contractions of the uterine wall, which start at the top of the uterus and work their way downwards in waves. During the early stages of labour the amniotic sac bursts (waters break) and the cervix gradually dilates (opens). The contractions become stronger and come more often until eventually the baby is expelled from the uterus and delivered through the vagina. Mrs Smith Ch18 Birth & Post-natal development

7. Induced Birth Nowadays, birth can be artificially induced by gradually injecting synthetic oxytocin (or a hormone which mimics its effect) into the mothers bloodstream. Mrs Smith Ch18 Birth & Post-natal development

8. Birth: Summary! Oxytocin: • Produced by pituitary gland. • Brings about uterine contractions during labour. • stimulates contractions of mammary gland muscle tissue resulting in milk ejection. • Labour can be induced by injection of oxytocin. Mrs Smith Ch18 Birth & Post-natal development

9. Nutrition of the Newborn Lactation Following parturition (the baby getting into position for birth) the hormone prolactin the mothers mammary glands become enlarged ready to produce milk. For milk to be released from the breasts– lactation the hormone oxytocin must be released. As well as stimulating the uterine contractions during labour, oxytocin stimulates contraction of muscle tissues in the mammary glands causing milk to be released. Mrs Smith Ch18 Birth & Post-natal development

10. Nutrition of the Newborn Colostrum Colostrum “mother-milk” is a yellow liquid produced by mammary glands a few hours after birth.  It is the first milk the baby receives. Colostrum is not only a source of protein, carbohydrate, fat, vitamins and minerals which are important for growth but it is also rich in maternal antibodies so gives the baby passive immunity against many diseases. Mrs Smith Ch18 Birth & Post-natal development

11. Nutrition of the Newborn A few days after birth normal breast milk is produced, which has fewer antibodies than colostrum but is richer in lactose sugar and fat. Mrs Smith Ch18 Birth & Post-natal development

12. If a baby it not breastfed Some mothers choose not to or find it too difficult to breast feed and instead feed their baby with powdered cow’s milk. This is also rich in the nutrients needed (especially proteins & minerals) by newborns. However this lacks the antibodies needed to protect the baby until it’s own immune system develops. Mrs Smith Ch18 Birth & Post-natal development

13. Nutrition of the Newborn Colostrumvs Normal Milk Mrs Smith Ch18 Birth & Post-natal development

14. FYI: Colostrums mature breast milk Mrs Smith Ch18 Birth & Post-natal development

15. FYI – breast milk contains many more essential vitamins and minerals to support healthy development Mrs Smith Ch18 Birth & Post-natal development

16. Nutrition of the Newborn Iron Iron is an essential part of our diet because it is needed to: Foods rich in iron: • Make many enzymes (e.g. catalase) • Make cytochrome (for aerobic respiration) • Form part of the haem group in haemoglobin Babies do not get an adequate supply of iron from milk. Instead, they make use of iron stored during gestation (pregnancy) until they begin to eat solid foods at about 6 months. Mrs Smith Ch18 Birth & Post-natal development

17. Contamination of Breast MilkOrganochlorides. • Organochlorides are non-biodegradeable chemicals used in pesticides on crops. • These can increase in concentration along the food chain and so are abundant in the final consumers (e.g. large fish, birds of prey, humans). • Stored in fatty tissue (these molecules are fat-soluble) including breast milk! Excessive concentrations of these chemicals have been found in breast milk (so high it exceeds legal limits for commercially produced foodstuffs), fortunately there are no known cases of babies becoming ill from this. Many of these chemicals (e.g. DDT) are now banned in many countries Mrs Smith Ch18 Birth & Post-natal development

18. A mini-clip: DDT in umbilical cords, it’s not a giant leap to assume there is traces in breast milk! Mrs Smith Ch18 Birth & Post-natal development

19. Nutrition: Summary • Prolactin stimulates lactation Oxytocin is needed to release the milk. • Colostrum – first milk. Yellowish fluid rich in antibodies. • Normal breast milk – fewer antibodies, rich in lactose and fat. May contain organochlorides from mother’s diet Mrs Smith Ch18 Birth & Post-natal development

20. Task: Torrance-TYK pg131 Qu’s 1&2 Mrs Smith Ch18 Birth & Post-natal development

21. Task: Torrance AYK pg135 Qu’s 1 Mrs Smith Ch18 Birth & Post-natal development

22. Learning Intentions Success Criteria Understanding the pattern of growth after birth and the influences of hormones on this. • Plot and interpret a human growth curve • Stat that body proportions vary through development from foetus to adult • Explain the role of growth hormone during normal development and the consequence of underproduction /overproduction. To study the effects of steriod use • Summarise • The major changes in males and females at puberty. • The hormonal changes in males and females at puberty. Mrs Smith Ch18 Birth & Post-natal development

23. Growth After Birth Measured as weight or height against time. When graphed this is called a growth curve. Mrs Smith Ch18 Birth & Post-natal development

24. Steady rapid growth No growth Units of growth e.g. Fresh mass, height Decelerating growth Accelerating growth Time Growth Curve When drawn as a graph, growth takes the form of a curved line, thus is called a growth curve. It contains two phases of rapid growth called growth spurts! This is a sigmoid (S-shaped) curve. Mrs Smith Ch18 Birth & Post-natal development

25. Growth spurt at puberty Slight loss of mass after birth Growth spurt (0-2 years) Human Growth: 2 main growth spurts Mrs Smith Ch18 Birth & Post-natal development

26. Growth Patterns Accelerating growth: Each daily increase is greater than previous. Steady rapid growth: Daily increase remains constant. Decelerating growth: Growth continues but each days growth is less than the previous days. *Exam tip: if describing graphs, include values in your answer! Mrs Smith Ch18 Birth & Post-natal development

27. Body Proportions Body proportions change as we grow from an embryo into an adult. Head of a baby = 25% of body length Head of an adult = 13% of body length The new-born baby’s lowers limbs = 33% of body length An adults lowers limbs = 50% of body length Mrs Smith Ch18 Birth & Post-natal development

28. Growth The brain normally approaches adult size on the fifth year. The sex organs remain dormant until adolescence. Mrs Smith Ch18 Birth & Post-natal development

29. Pituitary gland Human Growth Hormone (GH) = AKA SOMATOTROPIN. Hormones are chemical messengers, produced in the endocrine glands (e.g. pituitary gland) then secreted into the bloodstream. Mrs Smith Ch18 Birth & Post-natal development

30. somatotrophin Anterior (front) lobe Human Growth Hormone (GH) = AKA SOMATOTROPIN. Human Growth Hormone: aka Somatotrophin. • Somatotrophin - human growth hormone secreted by the anterior pituitary • The growth spurt which takes place during adolescence is due to an increased production of GH. Produced in the anterior lobe of the pituitary gland. Mrs Smith Ch18 Birth & Post-natal development

31. Human Growth Hormone (GH) = AKA SOMATOTROPIN. Promotes growth by • Accelerating amino acid transport into bone and soft tissue cells. • This in turn particularly enhances growth of bones (especially the long bones of the body in the arms and legs) and cartilage. • Stimulating the breakdown of fats for energy release allowing rapid synthesis of proteins. Mrs Smith Ch18 Birth & Post-natal development

32. Mrs Smith Ch18 Birth & Post-natal development

33. Pituitary Dwarfism • An under-production of GH during adolescence leads to a reduction in growth • Nowadays if a child is diagnosed with this condition they can be treated. Mrs Smith Ch18 Birth & Post-natal development

34. Pituitary Dwarfism in the German Shepherd Dog Mrs Smith Ch18 Birth & Post-natal development

35. Treatment for Dwarfism As the production of somatotrophin is controlled by a gene, scientists have used genetic engineering to transfer this gene into a bacterium to produce human growth hormone. The hormone is then extracted and used to treat children who show the early signs of pituitary dwarfism. Mrs Smith Ch18 Birth & Post-natal development

36. Giantism • An over-production of GH during adolescence leads to an abnormal increase in growth, especially in the long bones. Mrs Smith Ch18 Birth & Post-natal development

37. Acromegaly • Acromegaly occurs in about 6 of every 100,000 adults. It is caused by abnormal production of growth hormone after the skeleton and other organs finish growing. • Growth hormone normally decreases once adolescence is completed. • If excessive GH production occurs in adulthood, an abnormal increase in the bones of the hands, feet and jaw (not the long bones) occurs Mrs Smith Ch18 Birth & Post-natal development

38. Body Changes at Puberty The second growth spurt occurs at puberty. Until this stage the sex organs remain dormant, at puberty the sex organs become functional and a child changes into an adult. Males tend to reach puberty later than females. During puberty the body changes to develop secondary sexual characteristics. Primary sexual characteristics (e.g. possession of male/female genitals) occur at birth Mrs Smith Ch18 Birth & Post-natal development

39. Secondary sexual characteristics – happen during adolescence/puberty Mrs Smith Ch18 Birth & Post-natal development

40. Hormonal Changes at Puberty hypothalamus secretes releaser hormone transported in the bloodstream to the anterior pituitary gland releases gonadotrophic hormones (FSH and LH, or ICSH transported via the bloodstream to the gonads Production of sex hormones Mrs Smith Ch18 Birth & Post-natal development

41. Oestrogen & Progesterone Testosterone Controls menstrual cycle Development of secondary sexual characteristics Gonads The gonads (ovaries & testes) respond to gonadotrophic hormones • The sex hormones are steroid hormones: • fat soluble lipids • they can pass through cell membranes & switch on some of the targets cells genes Mrs Smith Ch18 Birth & Post-natal development

42. Essay Questions:SQA 2008 Give an account of the development of boys at puberty under the following headings: (i) physical changes; (3) (ii) hormonal changes. (7)(10) Mrs Smith Ch18 Birth & Post-natal development

43. Essay Questions:SQA 2002 Give an account of the influence of hormones on the growth and development of boys. (10) Mrs Smith Ch18 Birth & Post-natal development

44. Steroids in Sport Mrs Smith Ch18 Birth & Post-natal development

45. Steroids in Sport Anabolic steroids = male sex hormones (testosterone + man-made derivatives) • Taken as pills or injection • Used to increase muscle mass + strength • Problems of overuse: • masculinisation in women • shrinkage of testes • reduced sperm production • temporary sterility (ICSH & • FSH secretion is inhibited) • damage to liver, kidneys & heart • depression, aggression & • antisocial behaviour Mrs Smith Ch18 Birth & Post-natal development

46. Task: Torrance-TYK pg135 Qu’s 1&2 Mrs Smith Ch18 Birth & Post-natal development

47. Task: Torrance AYK pg126 Qu’s 2, 3, and 5 Mrs Smith Ch16 Intervention in fertility