1 Pregnancy, growth, and developmentChapter 23

2 Introduction After fertilization, 38 weeks of cell divisionSpecialization into distinct tissues/organs Growth- increase in size Development- continuous process, one life phase to another, includes growth Prenatal- fertilization to birth (pregnancy) Postnatal- birth to death

3 Fertilization Sperm nucleus unties with egg nucleus Zygote

4 Prenatal period Presence of developing offspring in uterusConsists of three trimesters (3 months) 38 weeks from conception to birth Three stages Cleavage Embryonic Fetal

5 Cleavage stage Rapid cell divisionCytoplasm divided, smaller and smaller cells (blastomeres)

6 Cleavage stage Zygote- fertilized eggMorula- solid ball of cells, cleavage and no growth Blastocyst- hollow ball of cells, embryoblast, trophoblast

8 Implantation Trophoblast Blastocyst Inner cell mass Uterine wallInvading trophoblast Inner cell mass Endometrium Implantation

10 Trophoblast cells secrete hCG hCG maintains corpus luteum Corpus luteum continues to secrete estrogens and progesterone Estrogens and progesterone promote growth, development, and maintenance of uterine wall

11 Embryonic stage Beginning of second week through eighth weekPlacenta forms Internal organs develop Major external body structures appear

12 Embryonic developmentYolk sac Ectoderm Mesoderm Skin Brain Heart Neural tube (Spinal cord) Amniotic fluid Digestive tract Endoderm Embryonic development Gastrulation Three layers

13 https://www. youtube. com/watchhttps://www.youtube.com/watch?v=k_9MTZgAhv0&list=PL3EED4C1D684D3ADF&index=17

14 Embryonic stage StructuresChorion- outer membrane, invades endometrium Amnion- inner layer, forms amniotic sac Yolk sac- nourishment before placenta Placenta Oxygen, nutrients, waste products, diffuse across membrane Bad stuff- carbon monoxide, alcohol, drugs, Rh antibodies, HIV, bacteria, viruses Umbilical cord- transport above, two arteries, one vein

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17 Placenta Fetal capillaries Umbilical vein Umbilical arteries Uterine wall Maternal blood in lacuna Diffusion Oxygen and nutrients into fetal blood Waste substances into maternal blood Chorionic villus Blood flow from fetus, branch of umbilical artery Blood flow to fetus, branch of umbilical vein

18 Fetal cardiovascular adaptationsBlood- hemoglobin has greater oxygen-carrying capacity Fetal hemoglobin vs. adult hemoglobin Takes 2 years, postnatal

19 Mandibular process Lens Developing eye Developing ear Maxillary process Elbow Forebrain Handplate Hindlimb Paddle-shaped forelimb (a) 35 ± 1 day (10–12 mm) (b) 37 ± 1 day (12.5–15.75 mm) External acoustic meatus Midbrain Pigmented eye External ear External ear Heart prominence Wrist Digital rays Toe rays Paddle-shaped foot plate (d) 45 ± 1 day (22–24 mm) (c) 40 ± 1 day (16–21 mm) – Eyelid Ear Webbed fingers Notches between toe rays (e) 49 ± 1 day (28–30 mm) Fingers separated Toes separated Fan-shaped webbed toes (f) 52 ± 1 day (32–34 mm) (g) 56 ± 1 day (34–40 mm)

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21 1 2 3 4 5 6 7 8 9 Eyes Ears Heart Month When physical structures develop Reproductive system Upper and lower limbs Central nervous system

22 Fetal stage End of 8th week Growth is rapid, body changes considerablyAt beginning, head is disproportionately large and limbs are short

24 Placenta takes over hormone productionMaintains uterine lining Inhibits FSH, LH Stimulates development of mammary glands Inhibit uterine contractions 2 4 Months of pregnancy 1 3 5 7 9 6 8 Increasing hormone concentration Estrogens Progesterone Human chorionic gonadotropin

26 Parturition Birth of babySecretion of progesterone decreases, lessens inhibiting effect on contractions, stimulates secretion of prostaglandins Stretching of uterus stimulates oxytocin release, stimulates uterine contractions (positive feedback)

29 Milk production/secretionPlacental estrogens/progesterone stimulate development of mammary glands Prolactin Secretion doesn’t begin until after birth Glandular tissue with secretions Glandular tissue Connective

30 Release Duct Secretion Milk Lumen Myoepithelial cellsNipple or areola of breast is stimulated Release Duct Secretion Milk Nerve impulses travel to hypothalamus Lumen Hypothalamus signals posterior lobe of pituitary gland to release oxytocin Myoepithelial cells Oxytocin causes myoepithelial cells surrounding alveolar glands to contract Milk is ejected from ductile system through nipple

31 Colostrum- proteins, antibodies, lower amounts of carbs/fats

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33 Postnatal period Birth until death Neonatal Infancy ChildhoodAdolescence Adulthood Senescence

34 Neonatal Birth until end of 4th weekBody adjusting to outside world- respiration, obtaining nutrients, digestion, excrete wastes, regulate body temp

35 Infancy End of 4th week to one year High growth rate TeethMaturation of muscular/nervous system Communication

36 Childhood One year to puberty High growth rate Permanent teethMuscle control (bladder/bowel) Increased intellectual abilities

37 Adolescence Puberty to adulthoodReproductively/emotionally more mature Growth spurts Increased motor skills/intellect

38 Adulthood Adolescence to old ageRelatively unchanged anatomically/physiologically Degenerative changes begin

39 Senescence Old age to death Degenerative changes continueBody becomes less able to cope with demands Death from various conditions/diseases

40 Senescence Integumentary- loss of collagen/elastin, pigmentationSkeletal- bone loss, compression of vertebrae Muscular- loss of muscle fibers Nervous- loss of connections, diminished processing ability Endocrine- inability to maintain homeostasis Cardiovascular- decreased resistance, output Immune- decreased efficiency Respiratory- reduced capacity Urinary- fewer functional nephrons

41 Aging Difficult to analyze, individualizedGerontology- biological changes of aging Active/passive

42 Passive aging Something that happens over timeBreak down of structures and slowing of functions Degradation of elastin/collagen, cell degradation- free radicals

43 Active aging New activities or substances Autoimmunity Apoptosis

44 Human life span Life expectancy is a projection of how long an individual will live 75.4 years men, 83.2 years women Medical advances contribute to improved life expectancy

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46 End of semester stuff Fun times! SRTE Final exam schedule