REPRODUCTION Topic 6.6 IB Biology Miss Werba

NERVOUS & ENDOCRINE SYSTEMS TOPIC 6 - PHYSIOLOGY 6.1 DIGESTIVE SYSTEM 6.2 CIRCULATORY SYSTEM 6.3 IMMUNE SYSTEM 6.4 RESPIRATORY SYSTEM 6.5 NERVOUS & ENDOCRINE SYSTEMS 6.6 REPRODUCTIVE SYSTEM J WERBA – IB BIOLOGY 2

THINGS TO COVER Structure of the adult male and female Reproductive Systems Role of hormones in the menstrual cycle Graph of hormone levels in the menstrual cycle Role of testosterone in males In vitro fertilisation (IVF): Process Ethical issues Risks J WERBA – IB BIOLOGY 3

THE MALE REPRODUCTIVE SYSTEM Command term = DRAW and LABEL 6.6.1 THE MALE REPRODUCTIVE SYSTEM Command term = DRAW and LABEL bladder vas deferens seminal vesicles prostate gland Cowper’s gland urethra scrotum penis epididymis testis (pl. testes) J WERBA – IB BIOLOGY 4

THE MALE REPRODUCTIVE SYSTEM 6.6.1 THE MALE REPRODUCTIVE SYSTEM Process of sperm production in tests = spermatogenesis Epididymis can store mature sperm for up to 4 weeks Vas deferens can store sperm for several months Alkalinity of semen neutralises acidity of vagina to help improve sperm motility Sperm move by using their tails like a propeller Semen contains fructose to nourish sperm and improve motility Dilation of blood vessels allows penis to become erect J WERBA – IB BIOLOGY 5

THE FEMALE REPRODUCTIVE SYSTEM Command term = DRAW and LABEL 6.6.1 THE FEMALE REPRODUCTIVE SYSTEM Command term = DRAW and LABEL fallopian tube funnel ovary ovarian ligament uterus endometrium uterine wall cervix vagina vulva J WERBA – IB BIOLOGY 6

THE FEMALE REPRODUCTIVE SYSTEM 6.6.1 THE FEMALE REPRODUCTIVE SYSTEM Process of ovum production = oogenesis Fallopian tubes are also known as the oviducts The endometrium changes throughout the menstrual cycle in preparation for the possible implantation of a fertilised ovum The vagina contains many organic acids, giving the vagina a very low pH to prevent microbial growth J WERBA – IB BIOLOGY 7

HORMONES & MENSTRUATION 6.6.2 HORMONES & MENSTRUATION There are 4 hormones involved in controlling the monthly cycle: FSH – Follicle Stimulating Hormone LH – Luteinising Hormone Progesterone Oestrogen J WERBA – IB BIOLOGY 8

HORMONES & MENSTRUATION 6.6.2 HORMONES & MENSTRUATION There are 4 hormones involved in controlling the monthly cycle: FSH – Follicle Stimulating Hormone LH – Luteinising Hormone Progesterone Oestrogen J WERBA – IB BIOLOGY 9

HORMONES & MENSTRUATION 6.6.2 HORMONES & MENSTRUATION Pituitary gland (in the brain) releases FSH: stimulates the ripening of the follicle The growing follicle releases oestrogen: increases endometrium thickness inhibits FSH production stimulates LH production J WERBA – IB BIOLOGY 10

HORMONES & MENSTRUATION 6.6.2 HORMONES & MENSTRUATION Pituitary gland releases LH: stimulates ovulation stimulates corpus luteum formation The corpus luteum produces progesterone: maintains endometrium inhibits FSH production inhibits LH production J WERBA – IB BIOLOGY 11

HORMONES & MENSTRUATION 6.6.2 HORMONES & MENSTRUATION If fertilisation does not occur: the corpus luteum degenerates FSH inhibition by progesterone is lost the pituitary will start producing FSH again to stimulate another follicle J WERBA – IB BIOLOGY 12

Pituitary Gland (Anterior Lobe) 6.6.2 HYPOTHALAMUS FSH LH Pituitary Gland (Anterior Lobe) Inhibits FSH Stimulates LH Inhibits FSH & LH Growing follicle Ovulation Corpus luteum Ovaries OESTROGEN PROGESTERONE Builds up endometrium Maintains endometrium 1 7 14 28 time/days Menstruation Menstruation J WERBA – IB BIOLOGY 13

HORMONES & MENSTRUATION 6.6.2 HORMONES & MENSTRUATION FSH OESTROGEN LH PROGESTERONE Produced by: Pituitary Ovary (follicle) Ovary (corpus luteum) Functions: Stimulates follicle growth Stimulates oestrogen secretion Stimulates progesterone secretion FSH surge stimulates ovulation Stimulates thickening of endometrium Promotes secondary sexual characteristics (eg. Breast development, widening of hips) Stimulates LH secretion Inhibits FSH secretion LH surge stimulates ovulation Stimulates corpus luteum formation Inhibits ovulation Maintains endometrium Inhibits FSH secretion Inhibits LH secretion J WERBA – IB BIOLOGY 14

Follicular phase Ovulatory phase Luteal phase 6.6.3 Menstruation LH FSH progesterone oestrogen J WERBA – IB BIOLOGY 15

6.6.4 TESTOSTERONE IN MALES Testosterone is a hormone produced by the testes. It functions to: Promote the male secondary sexual characteristics (eg. facial and chest hair, extra muscles, deeper voice) Promotes growth of the male reproductive organs Spermatogenesis Enhanced sexual desire (libido) Enhances immune function Protects against osteoporosis J WERBA – IB BIOLOGY 16

IN VITRO FERTILISATION (IVF) 6.6.5 IN VITRO FERTILISATION (IVF) IVF = in vitro fertilisation ‘in vitro’ literally means ‘in glass’ In this procedure, the egg and the sperm meet outside the female’s body. First “test tube baby” was Louise Brown, born in 1978. J WERBA – IB BIOLOGY 17

IN VITRO FERTILISATION (IVF) 6.6.5 IN VITRO FERTILISATION (IVF) IVF is used for many reasons, including: Female has blocked oviducts, which can occur due to an earlier infection Female is unable to produce viable eggs Female is unable to sustain a pregnancy Depending on the reasons, it may be possible to use the egg cells of the woman who wants to get pregnant. If not, donor eggs are used. J WERBA – IB BIOLOGY 18

IN VITRO FERTILISATION (IVF): Process 6.6.5 IN VITRO FERTILISATION (IVF): Process Drugs used to down-regulate the menstrual cycle: FSH injected  stimulates multiple follicles to develop HCG injected  causes follicles to mature Eggs are harvested/extracted (from the follicles/ovaries) Semen sample collected and processed to concentrate it. Healthy sperm is selected. Semen is brought into contact with the egg to allow fertilization: sperm is directly injected into egg when low numbers or motility are a factor semen is mixed with eggs in a dish/outside the body J WERBA – IB BIOLOGY 19

IN VITRO FERTILISATION (IVF): Process 6.6.5 IN VITRO FERTILISATION (IVF): Process Incubated at 37°C to allow embryos to develop Dish examined to choose healthiest embryo; Embryos are placed in uterus/oviduct, using a catheter or frozen so that they can be used later Pregnancy test/scan used to assess success. J WERBA – IB BIOLOGY 20

IN VITRO FERTILISATION (IVF): Ethics 6.6.6 IN VITRO FERTILISATION (IVF): Ethics The number of embryos placed in the uterus depends on several factors (including government legislation) If all embryos were to implant successfully, a multiple pregnancy may result. This could lead to a premature delivery and a reduced chance of survival for the babies. J WERBA – IB BIOLOGY 21

IN VITRO FERTILISATION (IVF): Ethics 6.6.6 IN VITRO FERTILISATION (IVF): Ethics Research the ethical issues associated with IVF including the risks to both mother and child(ren). Make a pros and cons list – with at least 3 ideas on each side of the argument. J WERBA – IB BIOLOGY 22

Sample questions Q1 The hormones progesterone and LH were measured in a woman’s blood over 40 days. When did her menstrual bleed start? J WERBA – IB BIOLOGY 23

Sample questions Q2 Outline the roles of FSH in the menstrual cycle. [2] FSH is secreted by the pituitary gland. During pregnancy, FSH secretion is inhibited. Suggest how FSH secretion could be inhibited during pregnancy. [1] Q3 Discuss the ethical issues surrounding IVF. [6] J WERBA – IB BIOLOGY 24

Sample questions A1 C A2 FSH stimulates follicle development; FSH stimulates estrogen secretion (by the follicle/ovary); high levels of progesterone or estrogen inhibit FSH production (during pregnancy) J WERBA – IB BIOLOGY 25

Sample questions A3 pros/positive considerations: [3 max] chance for infertile couples to have children; parents have consciously chosen to have a child; genetic screening of embryos could decrease suffering from genetic diseases; spare embryos can safely be stored for future pregnancies/used for stem cell research; cons/negative considerations: [3 max] IVF is expensive and might not be equally accessible; success rate is low therefore it is stressful for the couple; it is not natural/cultural/religious objections; could lead to eugenics/gender choice; could lead to (unwanted) multiple pregnancies with associated risks; production and storage of unused embryos / associated legal issues / extra embryos may be used for (stem cell) research; inherited forms of infertility might be passed on to children; J WERBA – IB BIOLOGY 26