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Reproductive Cycles and Patterns

Reproductive Cycles and Patterns. Reproduction is the production of new individuals by an existing member of the same species. It is a fundamental characteristic of living organisms Parents effectively pass on a copy of itself in the form of genetic material to another generation.

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Reproductive Cycles and Patterns

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  1. Reproductive Cycles and Patterns • Reproduction is the production of new individuals by an existing member of the same species. • It is a fundamental characteristic of living organisms • Parents effectively pass on a copy of itself in the form of genetic material to another generation. Reproduction Introduction to Reporduction http://www.youtube.com/watch?v=_7rsH2loIY8

  2. Formation of gametes • Gametes are formed via the process of meoisis. • Normal cells have a two sets of chromosomes, but gametes only have one set. • Gametes are haploid (one set of chromosomes) • Normal cells are diploid (two sets of chromosomes. One set from mom and one from dad)

  3. IB Assessment Statement • Draw and label diagrams of the adult female reproductive systems. • Bladder • urethra. • Oviduct • Ovary • Uterus • Vagina • Rectum • Cervix • Ureter • Ovary • Oviduct

  4. Animations • Video for Female Reproductive System • http://kidshealth.org/parent/interactive/frs_it.html • Menstrual Cycle Animation: • http://www.nhs.uk/Video/Pages/Menstrualcycleanimation.aspx • IVF Animation • http://www.abc.net.au/science/lcs/swf/ivf.swf

  5. Female Reproductive Parts • Ovaries – held near the bas of the abdominal cavity. • Produce gametes (ova or egg cells) • Ovaries are also considered endocrine glands • They secrete the hormone oestrogen and progesterone.

  6. Female Reproductive Parts • Oviducts (fallopian tubes) – extend from the uterus and open as funnels close to the ovaries. • Oviducts transport egg cells to the uterus • Fertilization takes place in the oviducts.

  7. Female Reproductive Parts • Uterus – is about the size and shape of a pear • Has a thick muscular wall • and an inner lining of mucous membrane that has a lot of blood vessels called the endometrium.

  8. Female Reproductive Parts • The endometrium of the uterus – undergoes the 28 day cycle. • The lining is built up each month in preparation of implantation of an embryo. • if NO implantation occurs the endometrium disintegrates and menstruation starts.

  9. Female Reproductive Parts • The vagina is a muscular tube that can enlarge • to allow entry of the penis • And exit of a baby

  10. Female Reproductive Parts • The cervix is where the vagina and uterus are connected.

  11. Female Reproductive Parts • The vulva is the opening of the vagina to the exterior.

  12. LE 46-9a Oviduct Ovary Uterus (Urinary bladder) (Pubic bone) (Rectum) Cervix Urethra Shaft Vagina Clitoris Glans Bartholin’s gland Prepuce Labia minora Labia majora Vaginal opening

  13. LE 46-9b Oviduct Ovaries Follicles Corpus luteum Uterine wall Uterus Endometrium Cervix Vagina

  14. IB Learning Objective • Draw and label diagrams of the adult male • bladder • urethra • erectile tissue • spermatic cord • urethra • penis • foreskin • glans • testis • scrotum • epidymis • rectum • prostrate glad • seminal vesicle • sperm duct • ureter

  15. Male Reproductive System • Testosterone hormone secreted by the cells of the testes has three functions: • It initiates the pre-natal (before birth) development of the male genitalia (penis, testes) • It triggers and regulates the development of secondary sexual characteristics • It maintains the sex drive (libido) in the adult.

  16. Male Reproductive System • Two Testes (singular testis) are situated in the scrotal sac. • They must be outside the body, because the optimum temperature for sperm production is 2-3 °C lower than body temperature.

  17. Male Reproductive System • Testes function is to produce male gametes spermatozoa (singular spermatozoon) or sperms. • Testes is also considered an endocrine gland because it released the hormone testosterone

  18. Male Reproductive System • Seminal vesicles and the prostrate gland are endocrine glands which secrete nutritive seminal fluid. • Seminal fluid travel to the outside of the body during a process called ejaculation via ducts • These ducts also store sperm

  19. Male Reproductive System • the urethra is a duct that runs inside the penis. • the urethra duct carries sperm and urine.

  20. Male Reproductive System • The penis also contains spongy erectile tissue that fills with blood when the male is sexually stimulated. • This causes a condition known as an erection. • The erect penis penetrate the vagina in sexual intercourse.

  21. LE 46-10b (Urinary bladder) Seminal vesicle (Rectum) (Public bone) Vas deferens Erectile tissue of penis Ejaculatory duct Prostate gland Urethra Bulbourethral gland Vas deferens Glans penis Epididymis Testis Prepuce Scrotum

  22. LE 46-10a Seminal vesicle (behind bladder) (Urinary bladder) Prostate gland Bulbourethral gland Urethra Erectile tissue of penis Scrotum Vas deferens Epididymis Glans penis Testis

  23. Secondary Sex Characteristics • Definition – characteristics that develop during puberty. • During puberty there is a significant increase in sex hormones. • Sex hormones (oestrogen, progesterone and testosterone) are called anabolic steroids, because they cause an increase in muscle and bone formation.

  24. Secondary Sex Characteristics of females • The increase of sex hormones cause the following secondary sexual characteristics of females during puberty • Maturation of ovaries • Enlargement of vagina and uterus • Widening of pelvis • Growth of pubic hair and under arm pits hair • Monthly ovulation and menstruation • Changes in behavior associated with sex drive

  25. Secondary Sex Characteristics of males • The increase of sex hormones (mainly Testosterone) cause the following secondary sexual characteristics of males during puberty • Development and enlargement of the testes, scrotum, penis and glands of the reproductive tract • Increased skeletal muscle development • Enlargement of larynx, deepening the voice • Growth of pubic hair, underarm hair and body and facial hair • Continuous production of sperm • Changes in behavior associated with sex drive

  26. IB Assessment Statement • 6.6.3 Outline the role of hormones in the menstrual cycle, including

  27. Animations • Video for Female Reproductive System • http://kidshealth.org/parent/interactive/frs_it.html • Menstrual Cycle Animation: • http://www.nhs.uk/Video/Pages/Menstrualcycleanimation.aspx • IVF Animation • http://www.abc.net.au/science/lcs/swf/ivf.swf

  28. Roles of Hormones in the control of reproduction • Puberty is triggered by the part of the brain called the hypothalamus. • Hypothalamus glands signals the pituitary gland to produce and release two hormones into the blood circulation • Follicle stimulating hormone (FSH) • Luteinizing hormone (LH)

  29. The Reproductive Cycles of Females • In females, the secretion of hormones and the reproductive events they regulate are cyclic

  30. The Human Female Reproductive Cycle: A Closer Look • The female reproductive cycle is one integrated cycle involving two organs: • the uterus • and ovaries

  31. The Human Female Reproductive Cycle: A Closer Look • Secretion of FSH and LH from the anterior pituitary orchestrates the female reproductive cycle • Four kinds of hormones participate in an elaborate scheme involving positive and negative feedback

  32. The menstrual cycle consists of two cycles • The ovarian cycle – occurs in the ovaries and is concerned with the monthly preparation and shedding of an egg cell from the ovaries • The uterus cycle – occurs in the uterus and is concerned with the build up of the uterine the build up of the uterine lining.

  33. Control by hypothalamus Inhibited by combination of estrogen and progesterone Hypothalamus Stimulated by high levels of estrogen GnRH Anterior pituitary Inhibited by low levels of estrogen FSH LH Pituitary gonadotropins in blood LH FSH FSH and LH stimulate follicle to grow LH surge triggers ovulation Ovarian cycle Degenerating corpus luteum Corpus luteum Growing follicle Mature follicle Follicular phase Ovulation Luteal phase Estrogen secreted by growing follicle in increasing amounts Progesterone and estrogen secreted by corpus luteum Ovarian hormones in blood Peak causes LH surge Progesterone Estrogen Estrogen level very low Progesterone and estro- gen promote thickening of endometrium Uterine (menstrual) cycle Endometrium Menstrual flow phase Proliferative phase Secretory phase Days 0 5 10 20 25 14 15 28

  34. The Ovarian Cycle • FSH Hormone is secreted by the pituitary gland • FHS stimulates the development of several immature egg cells (in the follicles) in the ovaries. • This follicle with the developing egg then secrets oestrogen.

  35. The Ovarian Cycle • Oestrogen has two targets • Stimulates the build up of the endometrium (uterus lining) in case of implantation of an embryo, should fertilisation take place • Inhibits FSH, which prevents more than one egg from being released (negative feedback)

  36. The Ovarian Cycle • Oestrogen concentration reaches its peak mid way through the cycle • High concentration of oestrogen stimulates the secretion of LH by the pituary gland

  37. The Ovarian Cycle • LH stimulates ovulation (release of egg) • LH also stimulates the formation of a temporary gland called a corpus luteum. • Corpus Luteum releases the hormone progesterone.

  38. The Ovarian Cycle • Progesterone has two targets: • In the uterus, it continues to build up the endometrium (uterus lining), to further prepare for implantation on a possible embryo • In the pituitary gland, it inhibits the secretion of LH and FSH (negative feedback control)

  39. The Ovarian Cycle to Uterine Cycle • When the levels of FSH and LH reach a low level in the blood stream, the corpus luteum (temporary gland) breaks down. • The breakdown of the corpus luteum causes the decrease in the levels of progesterone and oestrogen. • When the level of these above hormones are low it triggers for the endometrium lining to break down---- the start of the Uterine Cycle (menstrual cycle)

  40. If the egg is fertilized……… • The embryo itself becomes an endocrine gland • The embryo secretes a hormone that circulates in the blood . • The corpous luteum is maintained as an endocrine gland for 16 weeks of pregnancy.

  41. If the egg is fertilized……… • After 16 weeks the corpus luteum breaks down and the placenta takes over as an endocrine gland. • The placenta will secrete oestrogen and progesterone hormones to prevent ovulation.

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