Sexual Reproduction in the Human The Female – Structure & Hormones

Learning Objectives 1.Outline the general structure of the Female reproductive system 2.State the functions of the main parts of the reproductive system 3.Outline the role of meiosis to produce ova (egg) cells 4.Define the term secondary sexual characteristics 5.Outline the role of oestrogen, progesterone 6.Outline the events & outline the role of oestrogen and progesterone of the menstrual cycle

From your JC, label the following

=nLmg4wSHdxQ Answer the following 1.What is ovulation? 2.Where is an immature egg stored? 3.What hormone is released from the pituitary gland? 4.What causes the egg to move through the fallopian tubes?

Structure of the female reproductive system

Female Hormones Oestrogen and progesterone are the female hormones A combination of oestrogen and progesterone at puberty causes the development of the secondary female characteristics: – The maturing and enlargement of the breasts. – The widening of the pelvis to allow for birth. – The growth of pubic and underarm hair. – A growth spurt.

The Ovary These produce the eggs and female hormones (oestrogen, progesterone). The ovaries of a female foetus contains all the potential eggs at birth. These eggs have not yet divided by meiosis and as a result are diploid

The Ovary After puberty a number of eggs are produced by meiosis each month. Usually only one egg continues to grow … the rest die Once meiosis is complete the egg is surrounded within a structure called the Graafian follicle. This structure produces the female hormone oestrogen

The Ovary When mature the follicle forms a swelling on the outside of the ovary. It bursts at ovulation to release the egg After ovulation the follicle fills with yellow cells and becomes the Corpus luteum (yellow body). This secretes the hormone progesterone

The Fallopian tubes are muscular and approx 12cm long. Funnels at the tip of each tube catch the egg after it is released from the ovary. The egg is moved along the tube by cilia and muscular peristalsis. The egg is either fertilised or dies in the fallopian tube. The Fallopian tube (oviduct)

The Uterus (womb) Muscular structure approximately the size of your fist. Outer wall made of involuntary muscle. Inner lining is called the endometrium This lining thickens each month with cells and blood vessels to nourish the embryo.

The Uterus (womb) 1.Implantation: if egg is fertilised, it attaches to the lining 2.Hold foetus 3.Forms placenta The cervix separates the uterus from the vagina.

Elastic muscular tube 10cm long. Allows entry of sperm. Is the birth canal for the exit of a baby. Lined with cells that produce mucous. This serves to protect against the entry of pathogens. The vagina

Structure of the Female reproductive system Fallopian tube (Oviduct) Funnel Ovary Ovarian Ligament Uterus Lining of uterus (endometrium) Wall of uterus Cervix Vagina Vulva

Functions of the main parts of the female reproductive system Funnel Ovary Uterus Lining of uterus (endometrium) Wall of uterus Cervix Vagina Vulva Produces : 1.Egg 2.Oestrogen 3.Progesterone Ovarian Ligament Fallopian tube (Oviduct)

Funnel Ovary Uterus Lining of uterus (endometrium) Wall of uterus Cervix Vagina Vulva 1.Catches the egg after release from ovary 2.Transports egg from ovary to womb 3.Site of fertilisation Ovarian Ligament Fallopian tube (Oviduct) Functions of the main parts of the female reproductive system

Funnel Ovary Uterus Lining of uterus (endometrium) Wall of uterus Cervix Vagina Vulva 1.Implantation 2.Hold foetus 3.Forms placenta Ovarian Ligament Fallopian tube (Oviduct) Functions of the main parts of the female reproductive system

Funnel Ovary Uterus Lining of uterus (endometrium) Wall of uterus Cervix Vagina Vulva 1.Allows entry of sperm into female system 2.Birth canal to allow exit of baby Ovarian Ligament Fallopian tube (Oviduct) Functions of the main parts of the female reproductive system

Summary of functions of main parts of female reproductive system PartFunction Ovary To produce the egg (ova). To produce the hormones oestrogen and progesterone Fallopian tube (oviduct) Catches the egg from the ovary and transports it to uterus. Site of fertilisation. Uterus Site of implantation. Holds the developing embryo. Has a lining (endometrium) enriched with blood vessels to nourish the embryo. Forms the placenta. Vagina Allows entry of sperm and exit of baby at birth.

21 Egg versus sperm: can you see any differences

Egg versus Sperm Different size Different shape Sperm are mobile Chromosomal difference (sperm = y, egg = x) Survival rates: – sperm: up to 7 days – ova: up to2 days

Learning Check 1.What are the functions of the fallopian tubes 2.What is the lining of the uterus called 3.What are the 2 hormones produced by the ovaries? 4.Explain how these 2 hormones are produced.

The Menstrual Cycle Menstruation: shedding of endometrium in absence of fertilisation The menstrual cycle is a 28 day sequence of events that produces an egg and prepares the body for pregnancy. This cycle begins at puberty and continues until the menopause. Menopause: When ovulation and menstruation stops in a female

The Menstrual Cycle Summary of events in the menstrual cycle Days 1 – 5 The old lining of the uterus (endometrium) breaks down and is shed from the body. The loss of this blood and tissue is called menstruation (period). A new egg is produced in the ovary by meiosis. This new egg is surrounded by the Graafian follicle.

Days The hormone oestrogen is produced by the developing Graafian follicle. This has two functions: causes the lining of the uterus (endometrium) to build up again in preparation for implantation. prevents the development of any more eggs. Day 14 Ovulation: Graafian follicle bursts, egg is released. The Menstrual Cycle

Days The Graafian follicle now develops into the Corpus Luteum (yellow body). It secretes progesterone. This has two functions: It causes the endometrium to thicken even further. It also prevents new eggs from forming. The egg that was released will die by day 16 if it is not fertilised. Thus, days 11 – 18 of the menstrual cycle are referred to as the Fertile Period. (Even though the egg is not released until day 14, sperm, which can survive for a period of time in the female body, may already be present. Thus the fertile period begins on day 11).

If fertilisation does not take place the Corpus Luteum starts to degenerate around day 22. This results in a reduction in progesterone levels. As a result the lining of the uterus breaks down again on day 28. The menstrual cycle begins again with day 1.

The Menstrual Cycle DAY 1-5 : Blood from the womb lining is shed from the body After day 5 the lining of the uterus repairs and builds up again Fertile period Ovulation occurs on Day 14 Implantation may happen If fertilisation has not occurred the cycle begins again with the breakdown of the endometrium.

Outline the main events of the menstrual cycle. Summary: 1.Shedding of endometrium in absence of fertilisation 2.Graffian follicles with eggs secrete oestrogen and causes endometrium to thicken and prevent formation of more eggs 3.Ovulation occurs 4.Corpus luteum formed which produces progesterone (keeps uterus lining built up) 5.If no fertilisation occurs corpus luteum breaks down and progesterone levels drop. 6.Lining of uterus breaks down

Aidhm

Female infertility Cause: Blockage of Fallopian tubes due to scarring by an infection (STDs) Corrective measures: – Surgical opening of tubes – In vitro fertilisation: fertilisation outside the body. Eggs removed and fertilised with sperm in a dish. Placed back into uterus.

During the natural menstrual cycle an egg is produced by the ovary every month

During IVF fertility drugs are given to the female to stimulate the ovaries to produce more than one egg

These eggs are then taken from the females body and into the laboratory

In the meantime a sperm sample is taken from the male

The eggs and sperm are mixed together in the hope that fertilisation will occur

The sample is placed in the most ideal conditions for fertilisation to occur

The main aim of the procedure is to obtain a zygote. If successful the zygotes development will be monitored closely

If successful the zygote develops into a morula, blastocyst and eventually becomes an embryo

The developing embryo can now be placed back into the females body for implantation to take place

A menstrual disorder (HL) Fibroids – Benign, non-malignant tumours. – Grow on the wall of the uterus. – Found in woman years old. – Cause excessive menstrual bleeding. – Treatment: Radiation, left alone, womb removed.

(b) Draw a line graph in the space above A and B to illustrate the changes that take place in the thickness of the endometrium over the course of the cycle.

2.

The odd one out quiz… 1.Ovaries, cowpers gland, endometrium 2.Oestrogen, progesterone, LH 3.Corpus leutum, graafian follicle, yellow cells 4.High levels of progesterone, corpus leutum, graafian follicle 5.Fertilisation, cilia, cervix

Can you…. 1.Outline the general structure of the Female reproductive system 2.State the functions of the main parts of the reproductive system 3.Outline the role of meiosis to produce ova (egg) cells 4.Define the term secondary sexual characteristics 5.Outline the role of oestrogen, progesterone 6.Outline the events & outline the role of oestrogen and progesterone of the menstrual cycle

Exam Question

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