sexual reproduction in human beings. learning outcomes identify on diagrams of the male reproductive...

Sexual reproduction in Sexual reproduction in Human beingsHuman beings

Learning outcomesLearning outcomes Identify on diagrams of the male reproductive system Identify on diagrams of the male reproductive system

and give the functions of testes, scrotum, sperm and give the functions of testes, scrotum, sperm ducts, prostate gland, urethra and penisducts, prostate gland, urethra and penis

Identify on diagrams of the female reproductive Identify on diagrams of the female reproductive system and give the functions of ovaries, oviducts, system and give the functions of ovaries, oviducts, uterus, cervix and vaginauterus, cervix and vagina

Compare male and female gametes in terms of size, Compare male and female gametes in terms of size, numbers and mobilitynumbers and mobility

Describe the menstrual cycle with reference to the Describe the menstrual cycle with reference to the alternation of menstruation and ovulation, the natural alternation of menstruation and ovulation, the natural variation in its length, and the fertile and infertile variation in its length, and the fertile and infertile phases of the cyclephases of the cycle

Learning outcomes:Learning outcomes:

Describe fertilisation and early development of Describe fertilisation and early development of the zygote simply in terms of the formation of the zygote simply in terms of the formation of ball of cells which becomes implanted in the ball of cells which becomes implanted in the wall of uteruswall of uterus

Male reproductive organMale reproductive organ

The male reproductive systemThe male reproductive system

Testes (testis)Testes (testis) Organ that produce the gametes and male sex Organ that produce the gametes and male sex

hormone (testosterone)hormone (testosterone) The testis constantly divide to produce up to The testis constantly divide to produce up to

100,000,000 sperms per day.100,000,000 sperms per day. The testis work more efficiently at just below The testis work more efficiently at just below

body temperature, so they are held outside the body temperature, so they are held outside the body in scrotum.body in scrotum.


Storage duct/ epididymisStorage duct/ epididymis Sperms are stored in the storage duct Sperms are stored in the storage duct

temporarily in an inactive form before it enters temporarily in an inactive form before it enters the sperm duct.the sperm duct.


Sperm ducts/ Vas deferensSperm ducts/ Vas deferens Tubes which carry the sperm away from the Tubes which carry the sperm away from the

testestestes


Seminal vesicle/ Prostate glandSeminal vesicle/ Prostate gland Is about the size of the golf ballIs about the size of the golf ball It adds a nutrient fluid and enzyme (seminal It adds a nutrient fluid and enzyme (seminal

fluid) in which it activates the sperms to swim fluid) in which it activates the sperms to swim Sperms + seminal fluid = semenSperms + seminal fluid = semen


UrethraUrethra The urethra is a tube that carries both urine The urethra is a tube that carries both urine

and semen along the penis to be released from and semen along the penis to be released from the body but at different times.the body but at different times.


Penis Penis It is an organ for introducing sperms into the It is an organ for introducing sperms into the

female. It contains spongy tissue which fills female. It contains spongy tissue which fills with blood to make the penis firm (an with blood to make the penis firm (an erection).erection).

QUICK CHECK!QUICK CHECK!

State the functions of:State the functions of:

TestesTestes

ScrotumScrotum

Sperm ductsSperm ducts

Prostate glandProstate gland

UrethraUrethra

penispenis

Female reproductive organsFemale reproductive organs

The female reproductive systemThe female reproductive system

OvariesOvaries Female gonadsFemale gonads Making and releasing the female gametesMaking and releasing the female gametes The female releases one ovum every four The female releases one ovum every four

weeksweeks


Oviducts/ Fallopian tubeOviducts/ Fallopian tube Are tubes which carry the ova from the ovariesAre tubes which carry the ova from the ovaries They are lined with cilia together with a little They are lined with cilia together with a little

muscular assistance, help to move the ova muscular assistance, help to move the ova gently along.gently along.

The egg is fertilized in the oviduct.The egg is fertilized in the oviduct.


Uterus/ WombUterus/ Womb A pear shape organ A pear shape organ The wall contain involuntary muscleThe wall contain involuntary muscle The embryo develops in the uterus during The embryo develops in the uterus during

pregnancypregnancy


CervixCervix Cervix is the “neck” of the uterus, where the Cervix is the “neck” of the uterus, where the

uterus joins the vagina.uterus joins the vagina.


VaginaVagina it is part of the female system which receives it is part of the female system which receives

the penis during the sexual intercoursethe penis during the sexual intercourse It is muscular and stretchableIt is muscular and stretchable

QUICK CHECK!QUICK CHECK!

State the functions of:State the functions of:

OvariesOvaries

OviductsOviducts

UterusUterus

CervixCervix

vaginavagina

Checkpoint 1:Checkpoint 1:

Name the organ/ organs that carry out the function:Name the organ/ organs that carry out the function: Store matured spermsStore matured sperms Carries both sperm and urineCarries both sperm and urine Produces cells with only half the number of Produces cells with only half the number of

chromosomechromosome Produces the male sex hormoneProduces the male sex hormone Receive spermReceive sperm Egg must be fertilised here for pregnancy to Egg must be fertilised here for pregnancy to

take place.take place.

Female gametes vs male gametesFemale gametes vs male gametes

Female gametes vs male gametesFemale gametes vs male gametes

Male gametesMale gametes Released in millionsReleased in millions Able to moveAble to move Very small (0.05 mm)Very small (0.05 mm) Very little cytoplasmVery little cytoplasm

Nucleus contains either an Nucleus contains either an X or a Y chromosomeX or a Y chromosome

Female gametesFemale gametes Released one per monthReleased one per month Unable to move by their Unable to move by their

ownown Comparatively large Comparatively large

(o.1mm in diameter)(o.1mm in diameter) A lot of cytoplasm which A lot of cytoplasm which

contains nourishment for the contains nourishment for the zygote if the ovum is zygote if the ovum is fertilisedfertilised

Nucleus always contains an Nucleus always contains an X chromosomeX chromosome

QUICK CHECK!QUICK CHECK!Compare the human male and female Compare the human male and female gametes in terms of gametes in terms of

(i)(i)size, size,

(ii)(ii)numbers and numbers and

(iii)(iii)MovementMovement

In each case, suggest reasons for the In each case, suggest reasons for the differences you describe.differences you describe.

Human reproductive Human reproductive systemsystem

Menstrual cycleMenstrual cycle


The average menstrual cycle is about 28 days.The average menstrual cycle is about 28 days. Begins with puberty, ends with menopause. Begins with puberty, ends with menopause. Menstrual cycle is the alternation of Menstrual cycle is the alternation of

menstruation and ovulation.menstruation and ovulation.

Menstrual cycleMenstrual cycleMenstruation:Menstruation: The spongy lining then peel away , damaging the blood The spongy lining then peel away , damaging the blood

capillaries. The lining is passes out of the vagina, together capillaries. The lining is passes out of the vagina, together with the blood. Menstrual period. It lasts for about 5 dayswith the blood. Menstrual period. It lasts for about 5 days

Repair of uterine lining:Repair of uterine lining: Over a period of 14 days, the walls of the female’s uterus Over a period of 14 days, the walls of the female’s uterus

develop a spongy liningdevelop a spongy liningOvulation:Ovulation: On day 14On day 14thth, ovulation occurs. The ovum passes down the , ovulation occurs. The ovum passes down the

oviduct. If the ovum is not fertilised by sperm, it passes oviduct. If the ovum is not fertilised by sperm, it passes through the uterus and vagina and out of the vulva.through the uterus and vagina and out of the vulva.

Thickening of the liningThickening of the lining Lining continues to thicken for the next 10 – 12 days before it Lining continues to thicken for the next 10 – 12 days before it

begins to break down.begins to break down.


The fertile period is from day 11 to day 17, The fertile period is from day 11 to day 17, because ovulation has occurred. Ovum can because ovulation has occurred. Ovum can survive for 2-3 days and allowing for the survive for 2-3 days and allowing for the possible survival of sperms in the oviduct. possible survival of sperms in the oviduct.

The rest of the time is considered infertile The rest of the time is considered infertile period.period.

Factors affecting menstrual cycleFactors affecting menstrual cycle

StressStress Unbalanced diet/ malnutritionUnbalanced diet/ malnutrition Mental fatigueMental fatigue IllnessIllness

These factors can alter or stop the menstrual These factors can alter or stop the menstrual cyclecycle


There are many developing follicles in the There are many developing follicles in the ovary.ovary.

The young follicles are called primary folliclesThe young follicles are called primary follicles A primary follicles are matured into a mature A primary follicles are matured into a mature

follicle called Graafian follicle.follicle called Graafian follicle. The mature follicle releases hormone The mature follicle releases hormone

oestrogenoestrogen that brings about the that brings about the repair and repair and growth of the uterine lining.growth of the uterine lining.

During the ovulation, the one egg is released.During the ovulation, the one egg is released.

SummarySummary


The ovary secretes progesterone after The ovary secretes progesterone after ovulation.ovulation.

ProgesteroneProgesterone causes the uterine lining to causes the uterine lining to remain thick and softremain thick and soft and to become well and to become well supplied with blood vessels. This is important supplied with blood vessels. This is important for preparation of the for preparation of the implantation of embryo.implantation of embryo.


If no fertilisation occur, progesterone If no fertilisation occur, progesterone continues to be secreted for about ten days.continues to be secreted for about ten days.

Then stop producing progesterone and this will Then stop producing progesterone and this will cause the onset of menstruation.cause the onset of menstruation.

ReproductionReproduction

Fertilization and development of Fertilization and development of embryoembryo

FertilizationFertilization

The egg released is surrounded by a few layers The egg released is surrounded by a few layers of follicle cells.of follicle cells.

As the sperm swim toward the egg, it will As the sperm swim toward the egg, it will release enzymes that digest the follicle cells. release enzymes that digest the follicle cells. Only one sperm enters the egg.Only one sperm enters the egg.

The fusion of the nuclei to form the zygote is The fusion of the nuclei to form the zygote is called fertilization.called fertilization.

The fertilization occurs in oviduct.The fertilization occurs in oviduct.

Development of embryoDevelopment of embryo

The zygote passes along The zygote passes along the oviduct to the uterus the oviduct to the uterus and it begins to divide and it begins to divide by mitosis to form a ball by mitosis to form a ball of cells that called of cells that called embryo.embryo.

The embryo becomes The embryo becomes embedded in the uterine embedded in the uterine lining. This is called lining. This is called implantationimplantation..


placentaplacenta Finger –like projections (villi) to provide large surface area for Finger –like projections (villi) to provide large surface area for diffusiondiffusionAllow dissolved food substances (glucose, amino acid, Allow dissolved food substances (glucose, amino acid, mineral salts) and oxygen to diffuse from mother blood to the mineral salts) and oxygen to diffuse from mother blood to the embryoembryoAllow metabolic waste (urea and carbon dioxide) to diffuse Allow metabolic waste (urea and carbon dioxide) to diffuse from embryo to mother’s bloodfrom embryo to mother’s bloodAllow the antibodies to diffuse to the embryoAllow the antibodies to diffuse to the embryoProduce progesteroneProduce progesterone

umbilical umbilical cordcord

Contain umbilical vein and two umbilical arteriesContain umbilical vein and two umbilical arteries bring dissolved oxygen and nutrients by the umbilical vein to bring dissolved oxygen and nutrients by the umbilical vein to the foetus removing waste via umbilical arteries.the foetus removing waste via umbilical arteries.

amniotic amniotic fluidfluid

Provide the buoyancy to the foetus, thus protect it from shock Provide the buoyancy to the foetus, thus protect it from shock and mechanical injuriesand mechanical injuries

Maintains a relatively constant environment for the foetus.Maintains a relatively constant environment for the foetus.


The exchange of the material between the foetus and The exchange of the material between the foetus and the placenta.the placenta.

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The time between conception and birth is nine The time between conception and birth is nine months.months.

The nine months is known as the gestation The nine months is known as the gestation period.period.

At the end of the gestation period, contraction At the end of the gestation period, contraction of the uterus walls causes the rupture of the of the uterus walls causes the rupture of the amniotic sac.amniotic sac.

The birth of the baby is followed by the The birth of the baby is followed by the ejection of the placenta.ejection of the placenta.

Thinking room?Thinking room?

How are identical twins come about? Why do How are identical twins come about? Why do they always - look alike and same sex?they always - look alike and same sex?

IVFIVFA woman with blocked oviducts cannot have a baby in the normal way but A woman with blocked oviducts cannot have a baby in the normal way but

can now have a ‘test-tube’ baby. A doctor, using a fine tube through the can now have a ‘test-tube’ baby. A doctor, using a fine tube through the body wall, sucks up several eggs from the ovary, puts them in a dish and body wall, sucks up several eggs from the ovary, puts them in a dish and mixes them with sperm. The eggs are then kept for a few days before mixes them with sperm. The eggs are then kept for a few days before they are put back into the woman’s uterus via the cervix.they are put back into the woman’s uterus via the cervix.

a.a. Describe what can normally happen in the oviduct.Describe what can normally happen in the oviduct.b.b. Why does the doctor get the eggs from the ovary through the body wall Why does the doctor get the eggs from the ovary through the body wall

and not through the vagina and uterus?and not through the vagina and uterus?c.c. Why must the sperms be mixed with eggs before they are put back in the Why must the sperms be mixed with eggs before they are put back in the

woman?woman?d.d. Why do you think the eggs are kept for a few days before they are put Why do you think the eggs are kept for a few days before they are put

back into the uterus?back into the uterus?e.e. Why is the term ‘test-tube baby’ inaccurate?Why is the term ‘test-tube baby’ inaccurate?

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