Unit 2 - Physiology and Health Reproductive organs and hormonal control

Reproductive Organs and Gametes Prior Knowledge Reproductive organs produce gametes Male gamete- sperm Female gamete- egg/ova Male reproductive organ- testes Female reproductive organ-ovary

nucleus containing DNA Sex cells – sperm In males, the sex cells are called sperm. tail middle piece head cell membrane nucleus containing DNA Sperm are produced in sex organs called testes.

nucleus containing DNA Sex cells – egg In females, the sex cells are called eggs. nucleus containing DNA cytoplasm membrane jelly coat Eggs are produced in sex organs called ovaries.

Learning Intention: To learn about the structure and function of reproductive organs and gametes and their role in fertilisation Success Criteria: By the end of the lesson I should be able to State that gametes production takes place in the testes in males. Explain the role of the seminiferous tubules. Explain the role of the interstitial cells. Explain the role of testosterone in negative feedback. Explain the role of the prostate gland and seminal vesicles State that gametes production takes place in the ovaries in females. State that each ovum is surrounded by a follicle which secretes hormones. State that mature ova are released during ovulation. State where fertilisation takes place and that a zygote is formed.

Production of Gametes A germ line is the sex cells (eggs and sperm) that are used by sexually reproducing organisms to pass on genes from generation to generation. Gametes are produced by germline cells

MALE REPRODUCTIVE SYSTEM BLADDER URETER PUBIC BONE SEMINAL VESICLE PROSTATE GLAND RECTUM URETHRA ERECTILE TISSUE COWPER’S GLAND VAS DEFERENS PENIS EPIDIDYMIS SCROTUM TESTIS

Revision: The male reproductive system

TESTES SEMINIFEROUS TUBULE INTERSTITIAL CELLS

TESTES Seminiferous tubules – produce sperm Interstitial cells– secrete testosterone Interstitial cells

Accessory Glands Seminal vesicles and the prostate gland Semen consists of 10% sperm and 90% fluid and as sperm pass down the ducts from testis to penis, (accessory) glands add various secretion The prostate gland and seminal vesicles secrete fluids that maintain the mobility and viability of the sperm. This fluid is called semen Seminal vesicles secrete a fructose rich liquid, which provides energy for the mobility of the sperm The liquid also contains hormone like compounds (Prostaglandins) which stimulate contractions of the female reproductive tract Prostate gland secretes a thin lubricating liquid containing enzymes which regulate the viscosity of semen

FEMALE REPRODUCTIVE SYSTEM OVIDUCT ENDOMETRIUM OVARY UTERUS CERVIX VAGINA

Revision. The female reproductive system

THE OVARIES The ovaries contain immature ova in various stages of development Each ova is surrounded by a follicle that protects the developing ovum and secretes hormones Mature ova are released into the oviduct where they may be fertilised by sperm to form a zygote

GRAAFIAN FOLLICLE

Male or female?

Roles of the reproductive system

Human Ovulation

Fertilisation and implantation

Summary - You should know The structure and function of reproductive organs and gametes and their role in fertilisation. Gamete production in the testes. The roles of seminiferous tubules, interstitial cells, testosterone, prostate gland and seminal vesicles. Gamete production in the ovaries to include maturation of ova and the development of a follicle. Site of fertilisation in the oviduct and zygote formation.

Hormonal Control

Learning Intention: To learn about Hormonal control of reproduction Success Criteria: By the end of the lesson I should be able to State that the pituitary gland is stimulated to release FSH, LH (females) or ICSH (males) by the releaser hormone produced in the hypothalamus. Explain that in males FHS promotes sperm production and that ICSH stimulates the production of testosterone. State that testosterone also stimulates sperm production and activates the prostate gland and seminal vesicles. Describe the negative feedback mechanisms for controlling testosterone. Explain that in females, FSH stimulates the development of the Graafian follicle while LH triggers ovulation. State that FSH and LH trigger the ovaries to produce oestrogen and progesterone. Eexplain the role of oestrogen and progesterone in the menstrual cycle. Describe the mechanisms of negative feedback leading to menstruation.

Hormones Hormones are chemical messengers produced by cells that bind to receptors on the plasma membrane of other cells or enter other cells and alter the metabolic function of these cells. In response to a signal from the brain, hormones are secreted directly into the blood by the glands that produce and store them. These glands make up what is known as the endocrine system The testes and ovaries, or "gonads", are endocrine glands. In males, testes produce sperm and secrete the male sex hormone testosterone; in females, ovaries produce eggs and the female hormone oestrogen. It is these hormones that determine secondary sex characteristics like muscle mass and facial hair. They also help to orchestrate sperm production, menstruation and pregnancy.

Hormonal Onset of Puberty At puberty the hypothalamus secretes a releaser hormone that targets the pituitary gland Releaser hormones cause the release of other hormones to start and stop The pituitary gland is stimulated to release follicle stimulating hormone (FSH) Luteinising hormone (LH) in women Or interstitial cell stimulating hormone (ICSH) in men These hormones control the onset of puberty

Discuss in pairs what changes happen to the body during puberty? Produce two spider diagrams illustrating the changes that happen at puberty in both males and females. Question : What is the role of the hypothalamus and the pituitary gland in puberty?

Hormonal Control of Sperm Production

Male Hormones FSH (follicles stimulating hormones) promotes spermatogenesis in seminiferous tubules ICSH (Interstitial cell-stimulating hormone) stimulates interstitial cells to produce male hormones (eg testosterone) Testosterone also stimulates sperm production and activates the prostate gland and seminal vesicles FSH and ICSH exhibit negative feedback control on the pituitary gland decreasing the level of testosterone produced by the interstitial cells

NEGATIVE FEEDBACK CONTROL High levels of testosterone have an inhibitory effect on the pituitary gland Inhibits secretion of FSH and ICSH Thus, levels of testosterone fall Inhibitory effect on pituitary ceases FSH and ICSH secretion increases Levels of testosterone increase

SELF REGULATION OF TESTOSTERONE PITUITUARY GLAND Stimulates Inhibits Testosterone FSH ICSH SEMINIFEROUS TUBULES INTERSTITIAL CELLS

1. Analyse the diagram in pairs and explain what is happening. 2.Devise and complete a table to show hormones and their functions Hormone Function = stimulates   = inhibits

Essay Question Describe the influence of hormones on the testes.

Hormonal Control of the Menstrual Cycle

MENSTRUAL CYCLE Takes on average 28 days Menstruation is day 1 to 5 of the cycle Endometrium starts to repair Ovulation day 14 Endometrium thick and spongy Menstruation in absence of fertilised egg Consists of 2 phases-Follicular phase & Luteal phase

Follicular Phase FSH Causes development of follicles in ovary Stimulates secretion of oestrogen by the follicle oestrogen stimulates proliferation of the endometrium preparing it for implantation and affects the consistency of cervical mucus making it easier for sperm to penetrate

Luteal Phase LH Peak levels of oestrogen stimulate a surge in the secretion of LH which triggers ovulation Causes Graafian follicle to rupture (ovulation) Causes development of the corpus luteum from the follicle Stimulates the corpus luteum to secrete progesterone

Progesterone promotes further development and vascularisation of the endometrium preparing it to receive a blastocyst if fertilisation occurs. Ovum dies after 36 hours

Negative Feedback Effect of Ovarian Hormones on the Pituitary High levels of oestrogen and progesterone have an inhibitory effect on the pituitary gland Decrease the levels of FSH and LH which prevents further follicles from developing The lack of LH leads to degeneration of the corpus luteum A drop in progesterone leads to menstruation

Questions Name three reproductive processes that hormones control Name two female hormones produced by the pituitary What does testosterone do? What does high levels of oestrogen do to the cells lining the cervix? Name the two hormones that progesterone inhibits

Answers 1. Name three reproductive processes that hormones control the onset of puberty, sperm production, the menstrual cycle 2. Name two female hormones produced by the pituitary FSH and LH 3. What does testosterone do? Stimulates sperm production and activates the Seminal Vesicles and Prostate Gland to produce secretions 4. What does high levels of oestrogen do to the cells lining the cervix? High levels of oestrogen stimulates the cells lining the cervix to secrete a watery mucus easily penetrated by sperm 5. Name the two hormones that progesterone inhibits FSH and LH by the pituitary gland

Critical skills activity Your task is to find out about the role of the four female hormones and present this information in a form that others can learn from. This could be a poster, a PowerPoint presentation, a leaflet or another presentation form. You should include: accurate information labelled diagrams if appropriate information about the four female hormones: their roles in the menstrual cycle where they are produced what order they occur in in each menstrual cycle.   Each person in your group should be able to explain the role and function of each hormone.

Essay Question Describe the menstrual cycle under the following headings: The follicular phase (4 marks) The luteal phase (6 marks) Extension – Hormones Blind Date

Hormonal control of the menstrual cycle

Lasts approximately 28 days The first day of the menstruation is regarded as day 1 The cycle takes place in two phases – the first or Follicular Phase and the second or Luteal Phase Follicular Phase (day 114) During the first half of the cycle the pituitary gland releases FSH FSH has two effects

FSH – 2 effects 1. it causes a follicle to develop in the ovary 2. it stimulates the wall of the follicle and the tissues of the ovary to secrete the hormone oestrogen The immediate effect of oestrogen is to bring about healing and repair of the uterine wall In the course of the next 2 weeks the level of oestrogen in the body builds up

high oestrogen levels . . . . Peak levels of oestrogen stops the pituitary producing FSH and stimulates it to produce a surge in the secretion of LH The surge in LH triggers ovulation As stated previously, high oestrogen level affects the consistency of the cervical mucus -the mucus is more easily penetrated by sperm and leads to an increased chance of fertilisation

Luteal Phase (day1428) LH causes the follicle to change into the corpus luteum The corpus luteum secretes a hormone called progesterone Progesterone (and oestrogen) cause the continued proliferation and vascularisation of the endometrium in preparation for receiving a blastocyst During the next 10 days or so the concentration of progesterone inhibits the production of FSH and LH from the pituitary

uterus oviduct zygote blastocyst fertilisation egg ovary implantation

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Menstrual Cycle

MENSTRUAL CYCLE Takes on average 28 days Menstruation is day 1 to 5 of the cycle Endometrium starts to repair Ovulation day 14 Endometrium thick and spongy Menstruation in absence of fertilised egg Consists of 2 phases-Follicular phase & Luteal phase

Inhibition of FSH and LH Inhibition of FSH and LH – prevents further follicles from developing Stops the ovary producing oestrogen Causes the corpus luteum to degenerate and cease producing progesterone Sudden drop in oestrogen and progesterone causes menstruation to occur

Summary FSH and Oestrogen FSH follicle develops ovary secretes oestrogen Oestrogen Heals and repairs lining At high concentration, oestrogen inhibits FSH and stimulates pituitary to produce LH

Summary of LH and Progesterone LH sudden surge of LH causes ovulation LH changes follicle to corpus luteum Corpus luteum secretes progesterone Progesterone Progesterone and oestrogen cause further proliferation and vascularisation High progesterone inhibits FSH and LH

Towards end of cycle . . . . Ovary stops secreting oestrogen Corpus luteum stops producing progesterone No hormones to proliferate lining Menstruation

Questions What does the follicle develop into following ovulation? The menstrual cycle consists of the endometrial phase and the luteal phase? T or F FSH stimulates the ovary into secreting oestrogen? Oestrogen stimulates the proliferation of the endometrium? LH triggers the process of menstruation? Progesterone inhibits the secretion of FSH and LH by the Ovaries? Lack of LH leads to degeneration of the corpus luteum?

Answers . . . . Corpus luteum False, follicular True False, ovulation False, pituitary

Complete the table . . . . Hormone Site of production One function of the hormone Stimulates the development of the follicle Brings about development of corpus luteum Stimulates secretion of LH by the pituitary Promotes vascularisation of the endometrium

Answers . . . . FSH Pituitary gland LH Oestrogen Ovary Progesterone Hormone Site of production One function of the hormone FSH Pituitary gland Stimulates the development of the follicle LH Brings about development of corpus luteum Oestrogen Ovary Stimulates secretion of LH by the pituitary Progesterone Promotes vascularisation of the endometrium