Birth and Post-natal Development



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Birth and Post-natal Development

  • Unit 2
  • The Continuation of Life
  • 15/12/16

Unit 2: The continuation of life

  • Chapter 18:
  • Birth and Post-natal Development
  • Higher Human Biology
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  • Mrs Smith Ch18 Birth & Post-natal development

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.
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  • Understanding how the embryo develops inside the uterus and effects that the uterine environment can have on this development
  • Success Criteria
  • 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
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  • 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).
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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.

  • 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.
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  • Induced Birth
  • Nowadays, birth can be artificially induced by gradually injecting synthetic oxytocin (or a hormone which mimics its effect) into the mothers bloodstream.
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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.
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  • 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.
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  • 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.
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  • A few days after birth normal breast milk is produced, which has fewer antibodies than colostrum but is richer in lactose sugar and fat.
  • Nutrition of the Newborn
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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.
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Nutrition of the Newborn Colostrum vs Normal Milk

  • Colostrum Milk
  • Normal Milk
  • First Milk
  • Few days after birth
  • Rich in maternal antibodies
  • Contains fewer maternal antibodies
  • Richer in lactose and fat
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FYI: Colostrums mature breast milk

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FYI – breast milk contains many more essential vitamins and minerals to support healthy development

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  • 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.
  • 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
  • Nutrition of the Newborn
  • Iron
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Contamination of Breast Milk Organochlorides.

  • 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
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A mini-clip: DDT in umbilical cords, it’s not a giant leap to assume there is traces in breast milk!

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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
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Task: Torrance-TYK pg131 Qu’s 1&2

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Task: Torrance AYK pg135 Qu’s 1

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  • Learning Intentions
  • Understanding the pattern of growth after birth and the influences of hormones on this.
  • Success Criteria
  • 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.
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  • Growth After Birth
  • Measured as weight or height against time.
  • When graphed this is called a growth curve.
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  • 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.
  • Time
  • Units of growth e.g. Fresh mass, height
  • Accelerating growth
  • Decelerating growth
  • No growth
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  • Human Growth:
  • 2 main growth spurts
  • Growth spurt (0-2 years)
  • Growth spurt at puberty
  • Slight loss of mass after birth
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  • 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!
  • Growth Patterns
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  • 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
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Growth

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  • The brain normally approaches adult size on the fifth year. The sex organs remain dormant until adolescence.
  • Human Growth Hormone (GH) = AKA SOMATOTROPIN.
  • Pituitary gland
  • Hormones are chemical messengers, produced in the endocrine glands (e.g. pituitary gland) then secreted into the bloodstream.
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Human Growth Hormone (GH) = AKA SOMATOTROPIN.

  • somatotrophin
  • Anterior
  • (front)
  • lobe
  • Produced in the anterior lobe of the pituitary gland.
  • 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.
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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.
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  • Mrs Smith Ch18 Birth & Post-natal development

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.
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Pituitary Dwarfism in the German Shepherd Dog

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  • 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.
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Giantism

  • An over-production of GH during adolescence leads to an abnormal increase in growth, especially in the long bones.
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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
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  • 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
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Secondary sexual characteristics – happen during adolescence/puberty

  • Changes in females
  • Growth in height and weight
  • Growth in height and weight
  • Maturation of sex organs i.e. testes, scrotum and penis
  • Maturation of sex organs i.e. uterus, oviduct and vagina
  • Manufacture of sperm begins
  • Ovulation and menstruation begin
  • Increased growth of body hair
  • Deepening of voice
  • Widening of hips and growth of breasts
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  • Hormonal Changes at Puberty
  • Production of sex hormones
  • hypothalamus secretes releaser hormone
  • transported in the bloodstream to the anterior pituitary gland
  • releases gonadotrophic hormones (FSH and LH, or ICSH
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  • Gonads
  • The gonads (ovaries & testes) respond to gonadotrophic hormones
  • Oestrogen & Progesterone
  • Testosterone
  • The sex hormones are steroid hormones:
  • fat soluble lipids
  • they can pass through cell membranes & switch on some of the targets cells genes
  • Development of secondary sexual characteristics
  • Controls menstrual cycle
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Essay Questions: SQA 2008

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Essay Questions: SQA 2002

  • Give an account of the influence of hormones on the growth and development of boys. (10)
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  • Steroids in Sport
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  • 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
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Task: Torrance-TYK pg135 Qu’s 1&2

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  • Mrs Smith Ch18 Birth & Post-natal development

Task: Torrance AYK pg126 Qu’s 2, 3, and 5

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